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Dr. Kennedy's Vocabulary Course: -B-
(View Course for 11/18/2013)
(A B C D E F G H I J K L M)
 
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Ron Kennedy, M.D.
 
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(A B C D E F G H I J K L M)
Bacillus anthracis:  The bacterium that causes anthrax. Anthrax differs from most bacteria in that they exist in an inactive (dormant) state called spores. The spores are found in soil, animal carcasses and feces (including sheep, goats, cattle, bison, horses, and deer), and animal products (e.g., hides and wool). Some animals (cats, dogs, rats, and swine) are very resistant to anthrax. Remarkably, anthrax spores can remain dormant in soil for many years, perhaps decades. Likened somewhat to eggs that have the ability to hatch, spores can transform (germinate) into active bacteria under appropriate conditions. The spores themselves do not cause significant damage to tissue. Once in the body, the spores germinate to form the virulent (disease-causing) bacteria. Thus, the spores can lead to disease by: entering broken skin and germinating there to cause cutaneous anthrax; being inhaled and germinating in the lungs to cause inhalation anthrax; or being eaten and germinating in the gastrointestinal tract to cause gastrointestinal anthrax. Bacillus anthracis was discovered in 1850. Notably, it was actually the first bacterium to be shown to cause a disease. In fact, it was the great German physician, Robert Koch, who discovered this. He grew the anthrax bacteria in culture plates, injected them into animals, and thereby demonstrated that the bacteria produced the disease. Then, the famous French scientist, Louis Pasteur (known for pasteurizing milk), used anthrax bacteria that he damaged to develop a vaccine for anthrax. His idea was that the damaged bacteria would not cause the disease, but would still protect (produce immunity) against anthrax. Indeed, he showed that this vaccine protected animals from getting the disease when they were subsequently injected with healthy, virulent (disease-causing) anthrax bacteria. Recently terrorists have discovered bacteriology and specifically the qualities of anthrax which makes it a useful instrument to spread anxiety as well as disease.
Bartonella quintana:  Also called Rochalimaea quintana, this micro-organism is an unusual rickettsia that can multiply within the gut of the body louse and then can be transmitted to humans. Transmission to people can occur by rubbing infected louse feces into abraded (scuffed) skin or into the conjunctivae (whites of the eyes). Bartonella quintana (is the cause of trench fever, a disease that was first recognized in the trenches of World War I, when it is estimated to have affected more than a million people in Russia and on the fronts in Europe. Trench fever was again a major problem in the military in World War II and is seen endemically in Mexico, Africa, E. Europe, and elsewhere.
Borrelia burgdorferi:  The spirochete (a type of bacteria) that causes Lyme disease. Named after its discoverer, Dr. Willy Burgdorfer. See: Borrelia.
B cell:  A type of white blood cell, specifically, a type of lymphocyte. Many B cells mature into what are called plasma cells that produce antibodies (proteins) necessary to fight off infections while other B cells mature into memory B cells. All of the plasma cells descended from a single B cell produce the same antibody which is directed against the antigen that stimulated it to mature. The same principle holds with memory B cells. Thus, all of the plasma cells and memory cells "remember" the stimulus that led to their formation. B cells in mammals mature largely in the bone marrow. The B cell, or B lymphocyte, is thus an immunologically important cell. It is not thymus-dependent, has a short lifespan, and is responsible for the production of immunoglobulins. It expresses immunoglobulins on its surface.
B virus:  An infectious agent commonly found among macaque monkeys, including rhesus macaques, pig-tailed macaques, and cynomolgus monkeys. Monkeys infected with this virus usually have no or mild symptoms. In humans, however, B virus infection can result in a fatal encephalomyelitis. B virus disease in humans is extremely rare, but often fatal -- an estimated 80% of untreated patients die of complications associated with the infection. Persons at greatest risk for B virus infection include veterinarians, laboratory workers, and others who have close contact with Old World macaques or monkey cell cultures. Infection is typically caused by animal bites, scratches, or exposure to the tissues or secretions of macaques. The virus is also known as Cercopithecine herpes virus..
b.i.d. (on prescription):  Seen on a prescription, b.i.d. means twice (two times) a day. It is an abbreviation for "bis in die" which in Latin means twice a day. The abbreviation b.i.d. is sometimes written without a period either in lower-case letters as "bid" or in capital letters as "BID". However it is written, it is one of a number of hallowed abbreviations of Latin terms that have been traditionally used in prescriptions to specify the frequency with which medicines should be taken. Other examples include: q.d. (qd or QD) is once a day; q.d. stands for "quaque die" (which means, in Latin, once a day). t.i.d. (or tid or TID) is three times a day ; t.i.d. stands for "ter in die" (in Latin, 3 times a day). q.i.d. (or qid or QID) is four times a day; q.i.d. stands for "quater in die" (in Latin, 4 times a day). q_h: If a medicine is to be taken every so-many hours, it is written "q_h"; the "q" standing for "quaque" and the "h" indicating the number of hours. So, for example, "2 caps q4h" means "Take 2 capsules every 4 hours."
Babesiosis:  An illness caused by the parasite Babesia which is transmitted from animals to humans by ticks. In the US, it is typically contracted in the Northeast or Midwest -- in southern New England or New York State and in Wisconsin or Minnesota. The signs and symptoms include fever, chills, sweating, myalgias (muscle aches), fatigue, hepatosplenomegaly (enlargement of the liver and spleen) and hemolytic anemia (anemia due to break-up of red cells). Symptoms typically occur after an incubation period of 1 to 4 weeks and can last several weeks. The disease is more severe in patients who are immunosuppressed, splenectomized (lack their spleen), or elderly. It can cause death. Treatment involves antibiotics, usually clindamycin and quinine.
Babinski reflex (response or sign):  An important neurologic test based upon what the big toe does when the sole of the foot is stimulated. If the big toe goes up, that may mean trouble. The Babinski reflex is obtained by stimulating the lateral surface of the sole. The examiner begins the stimulation at the heel and goes forward to the base of the toes. There are diverse ways to elicit Babinski response. A useful way that requires no special equipment is with firm pressure from the examiner's thumb. Just stroke the sole firmly with the thumb from back to front along the outside edge. Care must be taken not to overdo it. Too vigorous stimulation may cause withdrawal of the foot or toe, which can be mistaken as a Babinski response. The Babinski reflex is characterized by extension of the great toe and also by fanning of the other toes. Most newborn babies are not neurologically mature and therefore show a Babinski response.
Babysitter's elbow (or Nursemaid's elbow):  Partial dislocation of the elbow. The radius (a bone in the forearm) slips out of the ligament that holds it in place at the elbow. This is common in children under 4 years of age. It may be due to an adult lifting or swinging the child by one hand and can also occur when an infant rolls over or falls. The child begins to cry immediately and holds the arm slightly bent at the elbow with the forearm against the abdomen. Treatment is for the physician to reduce the dislocation. Once a child has had nursemaid's elbow, it is more likely to recur.
Bacillary angiomatosis:  A bacterial infection due to a cat scratch most often seen today in people with HIV. The disease characteristically presents with swollen lymph nodes (lymphadenitis), sore throat, fatigue, and fever, chills, sweats, vomiting, loss of appetite, and weight loss. There is usually a little bump (a papule) which may be pus-filled (a pustule) at the site of the scratch. Then more nodules appear on and under the skin. As the number of nodules increases, patients get sicker. In normal people the disease is self-limited and usually goes away by itself in a few weeks. It can also be treated with antibiotics. In persons with AIDS it can cause severe inflammation of the brain, bone marrow, lymph nodes, lungs, spleen and liver. The disease can be fatal in persons with AIDS. It can be easily treated with antibiotics such as erythromycin and doxycycline. Treatment is given until the skin lesions resolve, usually in 3 to 4 weeks. Bacillary angiomatosis is so characteristic today of AIDS that it is an AIDS defining disease, according to the CDC (Centers For Disease Control). A cat carrying the microbe does not show symptoms. It is not necessary to get rid of the cat. If someone in the household is at high risk, a test to detect the infection can be done and the cat can be treated. The disease is caused by a bacterium called Rochalimaea henselae, which was reclassified as Bartonella henselae, named for Diane Hensel, a microbiologist. Bacillary angiomatosis has also been called cat scratch disease, cat scratch fever, regional lymphadenitis, and benign lymphoreticulosis.
Bacille Calmette Guérin:  An effective immunization against tuberculosis. Commonly abbreviated BCG, it is an attenuated (weakened) version of a bacterium called Mycobacterium bovis which is closely related to Mycobacterium tuberculosis, the agent responsible for tuberculosis. Camille Guérin (1872-1961) and Albert Calmette (1863-1933) produced the BCG strain of the bacteria at the Pasteur Institute in Paris in 1921. Within a decade BCG was being given in France and many other countries. By 1928, BCG had been given to 116,000 infants in France alone. However, conflicting reports about its effectiveness delayed the use of the BCG vaccine in the United States until 1950.
Bacillophobia:  An abnormal and persistent fear of bacilli (bacteria).
Bacillus:  A large family of bacteria that have a rod-like shape. They include the bacteria that cause food to spoil, and also those responsible for some types of diseases. Helpful members of the bacillus family are used to make antibiotics, or colonize the human intestinal tract and aid with digestion.
Background radiation:  Radiation that comes from environmental sources including the earth's crust, the atmosphere, cosmic rays, and radioisotopes. Natural sources of radiation account for the largest amount of radiation exposure received by most people each year with medical and occupational sources accounting for only a fraction of that exposure. It is currently believed that radon, a gas produced by radium decay within rock, constitutes the major source of background radiation throughout many parts of the US. The buildup of radon in inadequately ventilated homes may pose a long-term health hazard. The deleterious effects of background radiation, estimated as causing 1-6% of spontaneous genetic mutation, rise with dose.
Bacteremia:  The presence of live bacteria in the bloodstream. Bacteremia is analogous to viremia (the presence of a virus in the blood) and parasitemia (the presence of a parasite in the blood). Bacteremia, viremia and parasitemia are all forms of sepsis (bloodstream infection). The term "bacteremia" was compounded from "bacteria" and "-emia" (in the blood). Also called bacillemia.
Bacteria:  Single-celled microorganisms which can exist either as independent (free-living) organisms or as parasites (dependent upon another organism for life). Examples of bacteria include: Acidophilus, a normal inhabitant of yogurt, Chlamydia, which causes an infection very similar to gonorrhea, Clostridium welchii the most common cause of the dreaded gas gangrene, E. coli, the common peaceful citizen of our colon and, upon occasion, a dangerous agent of disease, and Streptococcus, the bacterium that causes the important infection of the throat strep throat. This are only a few of the thousands of species of known bacteria. Bacterium is the singular and bacteria the plural -- one bacterium, two bacteria. The term was devised in 1847 by the German botanist Ferdinand Cohn who based it on the Greek "bakterion," a small rod or staff.
Bacterial artificial chromosome:  A laboratory creation involving an artificially constructed chromosome in which medium-sized segments of DNA (100,000 to 300,000 bases in length) that come from another species are cloned into bacteria. Once the foreign DNA has been cloned into the bacteria's chromosome, many copies of it can be made (amplified) and sequenced. An example of this is the commercial production of human growth hormone. A human gene is spiced into E coli and the bacteria make the HGH which is then harvested and purified. Bacterial artificial chromosome is abbreviated BAC.
Bacterial prostatitis, acute:  Inflammation of the prostate gland of sudden (acute) onset due to bacterial infection. The symptoms include chills, fever, pain in the lower back and genital area, body aches, burning or painful urination, and the frequent and urgent need to urinate. The urinary tract is infected, as evidenced by the presence of the white blood cells and bacteria in the urine. Treatment is with antibiotics.
Bacterial prostatitis, chronic:  Longstanding bacterial infection of the prostate gland superimposed on a defect in the prostate. The symptoms can include low back pain, discomfort in the perineum (the area between the anus and the genitalia), testicular pain and, if the infection spreads to the bladder, mild pain or burning on urination (dysuria) and frequent and urgent need to urinate (frequency and urgency). The presence of white blood cells and bacteria in the urine attests to the fact that the urinary tract is infected with bacteria. The defect in the prostate is the focal point for the persistent infection. Effective treatment requires identification and correction of this defect before antibiotics can be effective.
Bacterial vaginosis:  A vaginal condition characterized by an abnormal vaginal discharge due to an overgrowth of normal bacteria in the vagina. Women with bacterial vaginosis have less of the normal vaginal bacteria called lactobacilli. Symptoms are the vaginal discharge and sometimes a fishy odor. A sign under the microscope is an unusual vaginal cell called a clue cell. A metanalysis of 18 separate studies involving over 20,000 women demonstrated that bacterial vaginosis predisposes to preterm pregnancy and the earlier a vaginal infection occurs in pregnancy, the greater is the risk of a preterm delivery. The metanalysis also revealed that bacterial vaginosis increases the risk of a spontaneous abortion nearly 10-fold. Bacterial vaginosis also can lead to infection of the amniotic fluid and of the uterus after delivery. Therefore, screening and treatment for bacterial vaginosis during pregnancy should be done.
Bacteriaphobia:  An abnormal and persistent fear of germs. Sufferers from bacteriaphobia experience undue anxiety even though they realize that most germs are not pathogens (disease-causing germs). To avoid germs, they may repeat cleaning rituals, such as washing their hands or face. (Surgeons may do well to have a mild degree of bacteriaphobia.)
Bacteriocidal:  Capable of killing bacteria. Antibiotics, antiseptics, and disinfectants can be bactericidal.
Bacteriology:  The science and study of bacteria and their relation to medicine and to other areas such as agriculture (e.g., farm animals) and industry. Bacteria are single-celled microorganisms which can live as independent organisms or, dependently, as parasites. Among the better known bacteria are strep, staph, and the agents of tuberculosis and leprosy. Bacteriology is a part of microbiology which encompasses the study of bacteria, viruses, and all other sorts of microorganisms.
Bacteriostatic:  Capable of inhibiting the growth or reproduction of bacteria. Different from bactericidal (capable of killing bacteria outright).
Bacterium:  . The single form of the plural ”bacteria.“ A single single-celled microorganism which can exist either as an independent (free-living) organism or as a parasite (dependent upon another organism for life).
Bag of waters:  Popular name for the amniotic sac together with the amniotic fluid within it. The amniotic sac is formed by the amnion within the uterus and encloses the fetus. This sac bursts normally during the birthing process, releasing the amniotic fluid.
Baker cyst:  A swelling in the space behind the knee (the popliteal space) composed of a membrane-lined sac filled with synovial fluid (the lubricant for the joints) that has escaped from the joint. Also called a synovial cyst of the popliteal space.
Baker's yeast:  Saccharomyces cerevisiae, the simplest single-cell organism that operates in a manner similar to a human cell and therefore an important model organism in genetics and molecular biology. The Saccharomyces cerevisiae genome has been sequenced.
Balanitis:  Inflammation of the rounded head (the glans) of the penis. Inflammation of the foreskin is called posthitis. In the uncircumcised male, balanitis and posthitis generally occur together as balanoposthitis: inflammation of both the glans and foreskin. Circumcision prevents balanoposthitis.
Ball-and-socket joint:  A ball-and-socket joint is one in which the round end of a bone fits into the cavity of another bone. The hip joints and the shoulder joints are ball-and-socket joints.
Balloon angioplasty:  Coronary angioplasty is accomplished using a balloon-tipped catheter inserted through an artery in the groin or arm to enlarge a narrowing in a coronary artery. Angioplasty is successful in opening coronary arteries in 90% of patients. 40% of patients with successful coronary angioplasty will develop recurrent narrowing at the site of balloon inflation.
Balloon tamponade:  A procedure in which a balloon is inflated within the esophagus or stomach to apply pressure on bleeding blood vessels, compress the vessels, and stop the bleeding. Used in the treatment of bleeding veins in the esophagus (esophageal varices) and stomach. The balloon used in the esophagus is shaped like a sausage while that in the stomach is rounded. Balloon tamponade is also called esophagogastric tamponade. The word "tamponade" is direct from the French. The French verb tamponner means to plug up. Compare the word tampon.
Banding of chromosomes:  The treatment of chromosomes to reveal characteristic patterns of horizontal bands like bar codes. The banding patterns lend each chromosome a distinctive appearance so the 22 pairs of human nonsex chromosomes and the X and Y chromosomes can be identified and distinguished without ambiguity. Banding also permits the recognition of chromosome deletions (lost segments), chromosome duplications (surplus segments) and other types of structural rearrangements of chromosomes.
Barber itch:  A superficial fungal infection of the skin in the bearded area of the face and neck, with swellings and marked crusting, often with itching, sometimes causing the hair to break off. The name harks back to the days when men went to the barber daily for a shave. Also known as tinea barbae. (Tinea = ringworm).
Bariatric surgery:  Surgery on the stomach and/or intestines to help a person with extreme obesity lose weight. Bariatric surgery is an option for people who have a body mass index (BMI) (weight in kilos divided by height in meters) above 40. Surgery is also an option for people with a BMI between 35 and 40 who have health problems like type 2 diabetes or heart disease.
Barium enema:  A series of x-rays of the lower intestine (colon) and rectum that are taken after the patient is given an enema with a white, chalky solution that contains barium as barium sulfate. The barium is radio-opaque and thus outlines the intestines on x-ray. These x-rays permit the detection of colon and rectal abnormalities including diverticulosis, diverticulitis, abnormal colon movement, dilation (widening) of the colon, polyps and cancers of the colon and rectum.
Barium solution:  A liquid containing barium sulfate. The barium shows up on x-rays. It outlines organs of the body such as the intestine so they can be seen on x-ray film.
Barium swallow:  An upper gastrointestinal series (barium swallow) is an X-ray test used to define the anatomy of the upper digestive tract. Women who are or may be pregnant should notify the doctor requesting the procedure and the radiology staff. The test involves filling the esophagus, stomach, and small intestines with a white liquid material (barium sulfate).
Barlow syndrome:  Barlow syndrome is mitral valve prolapse (also known as "click murmur syndrome"), the most common heart valve abnormality, affecting 5-10% of the world population. Most patients have no symptoms and require no treatment.
Baroparesis:  Reversible paralysis of the facial nerve due to pressure in the middle ear going up in a plane or surfacing in scuba diving. The excessive pressure in the middle ear compresses the facial nerve and causes temporary paralysis. After landing in a plane or surfacing in scuba diving, the ear pressure returns to normal and the nerve paralysis subsides. Also called alternobaric facial nerve palsy.
Barosinusitis:  Sinus troubles, particularly with pain, due to changing atmospheric pressures, as when going up or down in a plane. Also called aerosinusitis or sinus barotrauma.
Barotitis:  Middle ear problems due to changing atmospheric pressures, as when a plane descends to land. The problems include ear pain, ringing, diminished hearing and, sometimes, dizziness.
Barr body:  A microscopic feature of female cells due to the presence of two X chromosomes in the female. One of these X chromosomes is inactive and is crumpled up to form the Barr body.
Barrett esophagus:  A complication of severe chronic GERD (gastrointestinal reflux disease) involving changes in the cells of the tissue that line the bottom of the esophagus. These esophageal cells become irritated when the contents of the stomach back up (refluxes) and there is a small but definite increased risk of cancer (adenocarcinoma) of the esophagus.
Bartholin's glands:  A pair of glands between the vulva and the vagina that produce lubrication in response to stimulation. With a second pair of nearby glands called the lesser vestibular glands, they act to aid in sexual intercourse. Also called the greater vestibular glands.
Bartter syndrome:  A group of disorders that are inherited in an autosomal recessive manner and are characterized by impaired salt reabsorption by the kidney with pronounced salt wasting, hypokalemia (low blood potassium), alkalosis (an alkaline body pH), and hypercalciuria (high urine calcium).
Basal cell carcinoma:  The most common type of skin cancer, a disease in which the cancer cells resemble the basal cells of the epidermis, the outer layer of the skin. Basal cell carcinomas usually appear as the classic "sore that doesn't heal." A bleeding or scabbing sore that seems to get somewhat better, then recurs and starts to bleed, may be a basal cell carcinoma. Most basal cell carcinomas are on the face and neck where the skin is exposed to sunlight. However, a fair number show up on parts of the body such as the abdomen, leg, and scalp exposed to little or no sunlight. Basal cell carcinomas typically are locally invasive. They tend to burrow in locally and not metastasize (spread) to distant locations.
Basal cells:  Small, round cells found in the lower part, or base, of the epidermis, the outer layer of the skin.
Basal ganglia:  A region consisting of 3 clusters of neurons (called the caudate nucleus, putamen, and the globus pallidus) located at the base of the brain that are responsible for involuntary movements such as tremors, athetosis, and chorea. The basal ganglia are abnormal in a number of important neurologic conditions including Parkinson disease and Huntington disease. The term "basal ganglia" refers to the fact that this region is in the "basement" of the brain. Also called the basal nuclei.
Basal metabolic rate (or BMR):  A measure of the rate of metabolism. For example, someone with an overly active thyroid will have an elevated basal metabolic rate.
Basal temperature:  (1) Usually, a person's temperature on awakening in the morning. As changes in basal temperature accompany ovulation, it is often tracked by women who wish to ensure or avoid pregnancy. (2) A crude measure of thyroid function via taking and comparing basal temperatures (also called the Broda test after Dr. Broda Barnes.)
BASE breast cancer gene:  A breast cancer gene first reported in 2003 that encodes a protein secreted only by breast cancer and salivary gland cells. Hence the name, BASE (Breast cancer And Salivary gland Expression). The normal breast makes very little, if any, of the BASE protein whereas certain kinds of breast cancers produce quite a lot of it. Determining the levels of BASE in the blood may be of use in screening for breast cancer and for following a patient's progress on breast cancer treatment.
Base excision repair:  A process of DNA repair in which an altered base is excised (removed) by a DNA glycosylase enzyme, followed by excision of the resulting sugar phosphate. The small gap left in the DNA helix is then filled in by the sequential action of DNA polymerase and DNA ligase. Abbreviated BER.
Basic Local Alignment Search Tool:  Abbreviated BLAST. A computer program that identifies homologous genes in different organisms (such as worms, the fruit fly, mice, and humans). Homologous genes are genes in different species that share similar structures and functions.
Basilar:  Located at or near the base of a structure, especially the base of the skull. For example, a basilar fracture is a break in the bone at the base of the skull and can be life-threatening. Also, the basilar artery at the base of the skull.
Basilar fracture:  A break in bone at the base of the skull. About a half of basilar fractures are caused by bicycle or motor vehicle accidents, about a quarter by falls, and a tenth by recreational activities, particularly by diving accidents. The balance are due to other causes. No matter what cause, the risk of death with a basilar fracture is appreciable.
Baskerville effect:  A fatal heart attack triggered by extreme psychological stress. The effect is named after Charles Baskerville, a character in the Arthur Conan Doyle story "The Hound of the Baskervilles," who suffers a fatal heart attack due to extreme psychological stress. The term "Baskerville effect" was coined in 2001 in the course of a research study that found Chinese Americans and Japanese Americans had a 7% greater death rate from heart disease on the 4th day of the month (BMJ 2001;323:1443-1446). There was no such peak mortality for white Americans. Since both Chinese and Japanese regard the number four as unlucky, it appears that heart fatalities increase on psychologically stressful occasions. (The stressful nature of the number 4 for Chinese and Japanese comes from the fact that in Chinese (both Mandarin and Cantonese) and Japanese the words "four" and "death" are pronounced almost identically. Some Chinese and Japanese hospitals do not have a fourth floor or number any rooms "4." Mainland Chinese omit the number 4 in designating military aircraft. Japanese people may avoid traveling on the 4th of the month.)
Bather's eruption:  An intensely itchy rash due to contact with the tiny thimble jellyfish (Linuche unguiculata).
Bathophobia:  An abnormal and persistent fear of depths. Sufferers from bathophobia experience anxiety even though they realize they are safe from falling into or being consumed by depths. The feared object may be a long, dark hallway, a well or a deep pool or lake. "Bathophobia" is derived from the Greek "bathos" (depth) and "phobos" (fear).
Battered child syndrome:  An ongoing pattern of behavior in which children are physically abused. The battered child syndrome is a form of child abuse. Not until the 19th century were children granted the same legal status as domesticated animals in regard to protection against cruelty and/or neglect. In 1962 the term "battered child syndrome" entered medicine. By 1976 all states in the United States had adopted laws mandating the reporting of suspected instances of child abuse. Child abuse involves a complex and dangerous set of problems that include child neglect and the physical, emotional, and sexual abuse of children.
Battle fatigue:  The World War II name for what is known today as post-traumatic stress, this is a psychological disorder that develops in some individuals who have had major traumatic experiences (and, for example, have been in a serious accident or through a war). The person is typically numb at first but later has symptoms including depression, excessive irritability, guilt (for having survived while others died), recurrent nightmares, flashbacks to the traumatic scene, and overreaction to sudden noises. Post-traumatic stress became known as such in the 70s due to the adjustment problems of some Vietnam veterans.
Bayes theorem:  A probability principle set forth by the English mathematician Thomas Bayes (1702-1761). Bayes' theorem is of value in medical decision-making and some of the biomedical sciences. Bayes' theorem is employed in clinical epidemiology to determine the probability of a particular disease in a group of people with a specific characteristic on the basis of the overall rate of that disease and of the likelihood of that specific characteristic in healthy and diseased individuals, respectively. A common application of Bayes' theorem is in clinical decision making where it is used to estimate the probability of a particular diagnosis given the appearance of specific signs, symptoms, or test outcomes. For example, the accuracy of the exercise cardiac stress test in predicting significant coronary artery disease (CAD) depends in part on the "pre-test likelihood" of CAD: the "prior probability" in Bayes' theorem. In technical terms, in Bayes' theorem the impact of new data on the merit of competing scientific hypotheses is compared by computing for each hypothesis the product of the antecedent plausibility and the likelihood of the current data given that particular hypothesis and rescaling them so that their total is unity. In Bayes' theorem: The antecedent plausibility is termed the "prior probability." The likelihood of the current data given that particular hypothesis is called the "conditional probability." The rescaled values are called the "posterior probabilities."
Baylisascaris:  Infection by the raccoon roundworm. Baylisascaris procyonis is found commonly in raccoons. When infective eggs of this roundworm are ingested by humans, Baylisascaris larvae hatch in the intestine and travel through the organs and muscles. This is the larva migrans syndrome. Some cases have resulted in death. Signs and symptoms of infection may take a week or so after ingestion of eggs to develop.
BCG:  An effective immunization against tuberculosis. BCG stands for Bacille Calmette Guérin. BCG is a weakened (attenuated) version of a bacteria called Mycobacterium bovis which is closely related to Mycobacterium tuberculosis, the agent responsible for tuberculosis. Camille Guérin (1872-1961) and Albert Calmette (1863-1933) produced the BCG strain of the bacteria at the Pasteur Institute in Paris in 1921. BCG is used in alternative medicine as an adjunctive treatment of cancer
Beard ringworm:  A superficial fungal infection of the skin, affecting the bearded area of the face and neck, with swellings and marked crusting, often with itching, sometimes causing the hair to break off. In the days when men went to the barber daily for a shave, this affliction was called barber's itch. Also known as tinea barbae.
Becker muscular dystrophy:  A chronic, progressive muscle degeneration disease. A form of muscular dystrophy that is quite similar to Duchenne muscular dystrophy, except that patients with Becker do produce some of the key protein, dystrophin, whereas those with Duchenne do not. Progression of the disease in Becker type is slower than in Duchenne, and symptoms may appear as late as the mid-twenties.
Bed bug:  A blood-sucking bug in the Cimex family that lives hidden in bedding or furniture, coming out at night to bite their victims.
Bed sore:  A painful, often reddened area of degenerating, ulcerated skin caused by pressure and lack of movement, and worsened by exposure to urine or other irritating substances on the skin. Untreated bed sores can become seriously infected or gangrenous. Bed sores are a major problem for patients who are confined to bed or a wheelchair. They can be prevented by moving the patient frequently, changing bedding, and keeping the skin clean and dry. Also called a pressure sore, decubitus sore, or decubitus ulcer.
Bedwetting:  Involuntary urination in bed. Called "enuresis," (from the Greek "enourin" meaning "to urinate in"). This is considered a normal phenomenon in childhood up to the age of approximately 10 years.
Bee sting:  Stings from bees and other large stinging insects such as yellow jackets, hornets and wasps can trigger allergic reactions varying greatly in severity. Avoidance and prompt treatment are essential. In selected cases, allergy injection therapy is highly effective.
Bee sting, Africanized:  as above, except with Africanized honey bees, a special species of honey bees that are reportedly moving into the United States from the south. (Africanized honey bees are thought to have originally populated this hemisphere proliferating in Brazil in the 1950s.) This species of bees has an unusual and dangerous natural defense mechanism when disturbed. For instance, a loud noise or vibration near a hive, such as a barking dog or lawn mower, may cause the bees to display aggressive behavior. They attack in large numbers and for a longer period of than is typical of the common docile honey bee (European honey bee). As a result, Africanized honey bees when they attack inflict more stings, causing a higher dosage of bee venom to be injected into their victims. The lethal dose of honeybee venom is about 19 stings per kg of body weight (that is 1,300 stings for a 150 pound person). Animals (especially caged ones) as well as humans are at risk. Healthy people can often outrun the bees; however, the bees may give chase for as much as a quarter of a mile! Africanized honey bees cannot be eradicated after becoming established in areas.
Beef tapeworm:  Taenia saginata, the most common of the big tapeworms that parasitizes people, contracted from infected raw or rare beef. Can grow to be 12-25 feet (3.6-7.5 m) long in the human intestine. Also known as the African tapeworm.
Behavior therapy:  A treatment program that involves substituting desirable behavior responses for undesirable ones.
Behcet's disease or Bechet's syndrome:  A chronic inflammatory disorder involving the small blood vessels which is characterized by a classic triad of features: ulcers in the mouth, ulcers of the genitalia, and inflammation of the eye (uveitis). The mouth and genital ulcers recur in crops and are painful. The mouth ulcers appear on the inner lining of the mouth, the gums, and tongue. The genital ulcers occur on the scrotum and penis of males and vulva of women and can leave scars. Arthritis is commonplace with Behcet's syndrome, as is involvement of the gastrointestinal system and central nervous system. The cause of Behcet's syndrome is not known. It is more frequent and severe in patients from the Eastern Mediterranean and Asia than those of European descent. Treatment for Behcet's disease is symptomatic and supportive.
Bell's palsy:  Paralysis of the facial nerve, the nerve that supplies the facial muscles on one side of the face. Bell's palsy is also called facial nerve paralysis. The cause of facial nerve paralysis is often not known, but is thought to be due to a virus. The facial nerve is the 7th cranial nerve. The disease typically starts suddenly and causes paralysis of the muscles of the side of the face on which the facial nerve is affected. Treatment is directed toward protecting the eye on the affected side from dryness during sleep. Massage of affected muscles can reduce soreness. Sometimes prednisone is given to reduce inflammation during the first weeks of illness. The prognosis (outlook) with Bell's palsy is generally good. About 80% of patients recover within weeks to months.
Benign:  In a general sense, "benign" means of a mild character that does not threaten health or life. Floaters in the eye are benign. They have no significant effect on vision. A tumor can be benign, that is it will not metastasize or travel to a distant location and beging growing there as well.
Benign intracranial hypertension:  Increased pressure within the brain in the absence of a tumor. Symptoms may include headache, nausea, vomiting, pulsating intracranial noises, ringing in the ears, double vision, loss of visual accuracy, and even blindness. It is most common in women between the ages of 20 and 50. The cause is usually not known. The condition is associated sometimes with the use of tetracycline, nalidixic acid, nitrofurantoin, phenytoin, lithium, and amiodarone, and the extreme overuse of vitamin A. Drugs to reduce cerebrospinal fluid production or hyperosmotic drugs may be used to reduce fluid buildup. Treatment by removal of excess cerebrospinal fluid (CSF) may be achieved by repeated spinal taps, shunting or a type of surgery called optic nerve sheath fenestration that allows the excess fluid to escape. Steroids may be prescribed to reduce swelling of brain tissue. Diagnosis is by brain imaging and analysis of the CSF obtained by lumbar puncture. Benign intracranial hypertension is also called pseudotumor cerebri.
Benign lymphoreticulosis:  Also called cat scratch fever, a mild flu-like infection, with swollen lymph nodes (lymphadenitis) and mild fever of short duration, due to cat scratches, especially from kittens. There is usually a little bump (a papule) which may be pus-filled (a pustule) at the site of the scratch. The infection is self-limited and usually goes away by itself in a few weeks. It can also be treated with antibiotics, but it can cause a severe inflammation called bacillary angiomatosis in patients with weakened immune systems. A cat carrying the microbe does not show symptoms and it is not necessary to get rid of it. If someone in the household is at high risk, a test to detect the infection can be done and the cat can be treated. The disease is caused by a bacterium called Bartonella henselae, named for Diane Hensel, a microbiologist. The disease has also been called regional lymphadenitis.
Benign melanoma:  A tumor of the melanocytes that is not cancerous.
Benign paroxysmal positional vertigo (BPPV):  A balance disorder that results in the sudden onset of dizziness, spinning, or vertigo when moving the head.
Benign prostatic hyperplasia:  Abbreviated BPH. A noncancerous prostate problem in which the normal elements of the prostate gland grow in size and number. Their sheer bulk may compress the urethra, which courses through the center of the prostate, impeding the flow of urine from the bladder through the urethra to the outside. This leads to urine retention and the need for frequent urination. If BPH is severe, complete blockage can occur. BPH generally begins in a man's 30s, evolves slowly, and causes symptoms only after age 50. BPH is very common. Half of men over age 50 develop symptoms of PBH, but only 10% need medical or surgical intervention. Watchful waiting with annual medical monitoring is appropriate for most men with BPH. Medical therapy includes drugs such as finasteride (Proscar) and terazosin (Hytrin). Nutritional therapy is more effective. The active nutritionals are zinc, copper, flaxseed, sunflower, or safflower oil, vitamin E, Seronoa repens (Saw palmetto), cernilton (flower pollen), B-sitosterol (e.g. from Pygeum africanum), and pumpkin seed oil. There are several preparations on the market containing a selection of these nutrients and herbs. Prostate surgery has traditionally been seen as offering the most benefits and the most risks for symptomatic BPH but medial and nutritonal treatment has made surgery almost obsolete. BPH is not a sign of prostate cancer. Also known as benign prostatic hypertrophy and nodular hyperplasia of the prostate.
Benign recurrent aseptic meningitis:  Recurring meningitis without identifiable cause that leaves no residual damage to the nervous system. Benign recurrent aseptic meningitis is also called Mollaret meningitis. The cause of benign recurrent aseptic meningitis is not known. Benign recurrent aseptic meningitis is distinguished from viral meningitis by its recurrent character with symptom-free intervals between episodes. Symptoms include headache, neckache, fever, and neck stiffness and last from 1 to 7 days. There is usually rapid onset of symptoms of meningitis and resolution without residual damage to the nervous system. Symptom-free periods may last from weeks to years. A distinctive feature of benign recurrent aseptic meningitis are peculiar cells in the spinal fluid, called Mollaret cells, which are most often visible in the first day of the attack. Other causes of meningitis are typically excluded by testing, including tests of the brain, blood, and spinal fluid. There is no specific treatment for benign recurrent aseptic meningitis. Treatments that are used include medications for pain, colchicine, and acyclovir. The long-term outcome is excellent.
Benign sleep myoclonus:  A distinctive disorder of sleep in infancy characterized by rhythmic myoclonic jerks (sudden muscle contractions) which occur when the child is asleep and which stop when the child is awakened. Sleep myoclonus usually disappears after a few weeks, in most cases by 3 months of age, as the sleep patterns mature. Benign sleep myoclonus may be mistaken for epilepsy.
Benzene:  A highly toxic hydrocarbon known to cause anemia and leukemia. The anemia associated with benzene exposure is termed aplastic anemia. Benzene is used as a solvent. It comes from light coal tar oil and chemically is C6H6. The use of glues and other products containing benzene has stopped in most developed countries because of its danger and the allowable worker exposures to the chemical have been drastically reduced. In some countries such as China, however, the use of benzene-containing glues reportedly persists in thousands of small factories.
Benzidine:  A compound used mainly for dying textiles and paper that is a known human carcinogen (cancer-causing agent). Benzidine was one of the first chemicals for which an association of occupational exposure and increased incidence of urinary bladder cancer in humans was reported.
Benzo(a)pyrene:  Abbreviated B(a)P. A member of a class of compounds known as polycyclic aromatic hydrocarbons (PAHs). B(a)P, along with other PAHs, is suspected of causing cancer in humans.
Benzodiazepines:  A class of drugs that act as tranquilizers (e.g. Valium, Librium, Xanax, Halcyon, Rohypnol) and are commonly used in the treatment of anxiety. Benzodiazepines commonly cause drowsiness.
Bereavement:  The period after a loss during which grief is experienced and mourning occurs. The time spent in a period of bereavement depends on how attached the person was to the person who died, and how much time was spent anticipating the loss.
Bergamot oil:  An aromatic extract of the rind of the bergamot orange used to flavor Earl Grey tea and in aromatherapy. It causes photosensitivity, due largely to the presence of 5-methoxypsoralen. Drinking very large amounts of Earl Grey tea can block the intestinal absorption of potassium.
Beriberi:  A syndrome characterized by inflammation of multiple nerves (polyneuritis), heart disease (cardiopathy), and edema (swelling) due to a deficiency of thiamine (vitamin B1) in the diet.
Bernard-Soulier syndrome (giant platelet syndrome):  A primary problem of platelets in which the platelets lack the ability to stick adequately to injured blood vessel walls. This is a crucial aspect of the process of forming a blood clot, and as a result of this problem there is abnormal bleeding.
Bernstein test:  A test to find out if heartburn is caused by acid in the esophagus and so to diagnose GERD (gastroesophageal reflux disease). The test involves dripping a mild acid, similar to stomach acid, through a tube placed in the esophagus. Also called the esophageal acid infusion test.
Berry aneurysm:  a small outpouching (an aneurysm) that looks like a berry and classically occurs at the point at which a cerebral artery departs from the circular artery (the circle of Willis) at the base of the brain. Berry aneurysms are prone to rupture and bleed. Also called a brain aneurysm. Mortality of a ruptured berry aneurysm is about 50%.
Berserk:  Frenzied, enraged. From the Norse berserkr, Norse warriors who worked themselves into a frenzy. (No relation to the university located in Berzerkly, California.)
Berylliosis:  Beryllium poisoning, a toxic metal found in ores containing other elements that is used in making metal alloys for nuclear reactors and the aerospace industry. Acute exposure to beryllium fumes can cause a severe, sometimes fatal pneumonitis (inflammation of the lungs). Chronic overexposure to beryllium is more common and causes a diffuse inflammatory reaction in the lungs resulting in granulomas and fibrosis of the lungs and, in time, increasing shortness of breath.
Beta adrenergic blocking drugs:  A class of drugs, also called beta blockers, that block beta-adrenergic substances such as adrenaline (epinephrine), a key agent in the "sympathetic" portion of the autonomic (involuntary) nervous system. By blocking the action of the sympathetic nervous system on the heart, these agents relieve stress on the heart. They slow the heart beat, lessen the force with which the heart muscle contracts and reduce blood vessel contraction in the heart, brain, and throughout the body. Beta blockers can serve to treat abnormal heart rhythms (cardiac arrhythmias). They are used specifically to prevent abnormally fast heart rates (tachycardias) or irregular heart rhythms such as premature ventricular beats. Since beta blockers reduce the demand of the heart muscle for oxygen and the chest pain of angina pectoris occurs when the oxygen demand of the heart exceeds the supply, beta blockers can be useful in treating angina. They have also become an important drug in improving survival after a person has had a heart attack. Thanks to their effect on blood vessels, beta blockers can lower the blood pressure and be of value in the treatment of hypertension. Other uses for beta blockers include the prevention of migraine headaches and the treatment of certain types of tremors (familial or hereditary essential tremors). They are useful for about three weeks and then the effects wear off. They are not recommended to be used more than three weeks. Unfortunately, doctors tend to ignore that recommendation and leave people on these drugs for years with little if any beneficial effect.
Beta agonist (also written Beta-agonist):  A bronchodilator medicine that opens the airways by relaxing the muscles around the airways that may tighten during an asthma attack or in COPD (chronic obstructive pulmonary disease). Beta-agonists can be administered by inhalers or orally. They are called "agonists" because they activate the beta-2 receptor on the muscles surrounding the airways. Activation of beta-2 receptors relaxes the muscles surrounding the airways and opens the airways. Dilating airways helps to relieve the symptoms of dyspnea (shortness of breath). Beta-2 agonists have been shown to relieve dyspnea in many asthma and COPD patients. The action of beta-2 agonists starts within minutes after inhalation and lasts for about 4 hours. Because of their quick onset of action, beta-2 agonists are especially helpful for patients who are acutely short of breath but, because of their short duration of action, several doses of beta-agonists are often necessary each day. The side effects of beta-2 agonists include anxiety, tremor, palpitations or fast heart rate, and low blood potassium. Examples of beta-2 agonists include albuterol (Ventolin, Proventil), metaproterenol (Alupent), pirbuterol (Maxair), terbutaline (Brethaire), isoetharine (Bronkosol), and Levalbuterol (Xopenex). Beta-2 agonists with a slower onset of action but a longer period of activity such as salmeterol xinafoate (Serevent) are now available. Salmeterol has a duration of action of twelve hours and need only be taken twice a day.
Beta blocker:  A class of drugs that block beta-adrenergic substances such as adrenaline (epinephrine) in the "sympathetic" portion of the autonomic (involuntary) nervous system. By blocking the action of the sympathetic nervous system on the heart, beta blockers relieve stress on the heart; they slow the heart beat, lessen the force with which the heart muscle contracts, and reduce blood vessel contraction in the heart, brain, and throughout the body. Beta blockers may be used to treat abnormal heart rhythms (cardiac arrhythmias) and prevent abnormally fast heart rates (tachycardias) or irregular heart rhythms such as premature ventricular beats. Since beta blockers reduce the demand of the heart muscle for oxygen and the chest pain of angina pectoris occurs when the oxygen demand of the heart exceeds the supply, beta blockers can be useful in treating angina. They have also become an important drug in improving survival after a person has had a heart attack. Thanks to their effect on blood vessels, beta blockers can lower the blood pressure and be of value in the treatment of hypertension. Other uses for beta blockers include the prevention of migraine headaches and the treatment of certain types of tremors (familial or hereditary essential tremors). The beta blockers (with brand names) include: acebutolol (Sectral), tenolol (Tenormin), bisoprolol (Zebeta), metoprol (Lopressor, Lopressor LA, Toprol XL), nadolol (Corgard), and timolol (Blocadren). Beta blockers are also available in combination with a diuretic as, for example, with bisoprolol and hydrochlorothiazide (Ziac). Beta blockers reduce the pressure within the eye (the intraocular pressure), probably by reducing the production of the liquid (aqueous humor) within the anterior chamber of the eye, and so are used to lessen the risk of damage to the optic nerve and loss of vision in glaucoma. Beta blocker preparations for this purpose include timolol ophthalmic solution (Timoptic) and betaxolol hydrochloride (Betopic, Betopic S).
Beta carotene:  A vitamin that acts as an antioxidant, protecting cells against oxidation damage. Beta carotene is converted by the body to vitamin A. Food sources of beta carotene include vegetables such as carrots, sweet potatoes, spinach and other leafy green vegetables; and fruit such as cantaloupes and apricots. Excessive carotene in the diet can color the skin yellow, a condition called carotenemia. Carotenemia is sometimes seen in infants fed too many mashed carrots and is a reversible condition.
Beta cell of the pancreas:  A type of cell in the pancreas (the organ of the digestive system located behind the stomach). Within the pancreas, the beta cells are located in areas called the islets of Langerhans. They constitute the predominant type of cell in the islets. The beta cells are important because they make insulin. Degeneration of the beta cells is the main cause of type I (insulin-dependent) diabetes mellitus.
Beta-defensin:  A family of potent antibodies made within the body by neutrophils (a type of white blood cell) and macrophages (cells that can engulf foreign particles). The defensins play important roles against invading microbes. They act against bacteria, fungi and viruses by binding to their membranes and increasing membrane permeability. On a chemical level, the defensins are small peptides unusually rich in the amino acid cysteine.
Beta-secretase:  An enzyme that appears to be directly involved in the early development of Alzheimer's disease. Beta-secretase is a protease (an enzyme that catalyses the splitting of interior peptide bonds in a protein). Beta-secretase acts by trimming off a protein protruding from a brain cell. This small snip is thought to be the first step in the buildup of microscopic balls of debris known as amyloid that are toxic to brain cells. The brain cells (neurons) gradually die and with them slowly go the person's memory and other mental faculties. The discovery of beta-secretase was made in 1999 and may lead to the development of drugs designed to block this enzyme and hopefully block the progression of Alzheimer's disease.
Bezoar:  A clump or wad of swallowed food and/or hair. Bezoars can sometimes be found to cause blockage of the digestive system, especially at the exit of the stomach. When a bezoar is composed of hair, it is referred to as a hairball or trichobezoar. When a bezoar is composed of vegetable materials, it is referred to as a phytobezoar or foodball. When a bezoar is composed of hair and food it is referred to as a trichophytobezoar or hairy foodball. Interestingly, in the Far East culture, bezoars are felt to have medicinal properties!
Bicarbonate:  In medicine, bicarbonate usually refers to bicarbonate of soda (sodium bicarbonate, baking soda) white powder that is common ingredient in antacids. Also, the bicarbonate level is an indirect measure of the acidity of the blood that is determined when electrolytes are tested. The normal serum range for bicarbonate is 22-30 mmol/L.
Bicornuate:  Having two horns or horn-shaped branches. The uterus is bicornuate (with two "branches" leading into the ovarian tubes (also called the Fallopian tubes).
Bicuspid:  Having two flaps or cusps. The heart valve that is called the bicuspid valve is located between the left atrium and left ventricle. Although the aortic valve in the heart normally is tricuspid (with three cusps), it may sometimes be bicuspid.
Bicuspid aortic valve:  Whereas the normal aortic valve in the heart has three flaps (cusps) that open and close, a bicuspid valve has only two. There may be no symptoms in childhood, but in time the valve may become stenotic (narrowed), making it harder for blood to pass through it, or the valve may start to let blood leak backwards through the valve (regurgitate). Treatment depends on how the valve is working.
Bicycle helmet:  A well-known but often neglected device designed to protect the head of a bicyclist. Helmets decrease the risk of head injuries (traumatic brain damage) by about 85%. However, only about 18% of bicyclists in the US use helmets all or most of the time. Universal helmet use could prevent an average of 500 bicycle-related deaths each year in the US alone.
bid (on prescription):  Seen on a prescription, bid means twice (two times) a day. It is an abbreviation for bis in die which in Latin means twice a day. The abbreviation bid is sometimes written without a period either in lower-case letters as "bid" or in capital letters as "BID" or with periods as "b.i.d." However it is written, it is one of a number of hallowed abbreviations of Latin terms that have been traditionally used in prescriptions to specify the frequency with which medicines should be taken.
Biermer's anemia:  A blood disorder caused by a lack of vitamin B12. Patients who have this disorder do not produce the substance in the stomach that allows the body to absorb vitamin B12. This substance is called intrinsic factor (IF). Biermer's anemia, better known as pernicious anemia (PA), is characterized by the presence in the blood of large, immature, nucleated cells (megaloblasts) that are forerunners of red blood cells. (Red blood cells, when mature, have no nucleus). It is thus a type of megaloblastic anemia. Nowadays PA is an unpernicious anemia. It is simply treated with vitamin B12. The vitamin B12 has to be administered by injection (parenterally) because people with PA do not have IF (or an effective form of IF) and so cannot absorb vitamin B12 taken by mouth.
Bietti crystalline dystrophy:  A genetic eye disease that leads to progressive night blindness and visual field constriction and is characterized by the formation of crystals in the cornea (the clear covering of the eye), yellow shiny deposits on the retina, and progressive atrophy of the retina and choroid (the back layers of the eye). Average age of onset is 29. Lipid inclusions are present not only in the cornea but also in blood lymphocytes, suggesting a systemic disorder of lipid metabolism. There is no known treatment.
Bifid:  Cleft (split) in two. For example, bifid uvula (that little gizmo which hangs down from the back of the palate). Cleft uvula is a common minor anomaly occurring in about 1% of whites and 10% of Native Americans. Persons with a cleft uvula should not have their adenoids removed because, without the adenoids, they cannot achieve proper closure between the soft palate and pharynx while speaking and develop hypernasal speech.
Big toe sign:  An important neurologic examination based upon what the big toe (and other toes) do when the sole of the foot is stimulated. If the big toe goes up, that may mean trouble. The big toe response, also called the Babinski reflex, is obtained by stimulating the external portion (the outside) of the sole.
Bilateral:  Having, or relating to, two sides. Bilateral is as opposed, for example, to unilateral (which means having, or relating to, one side). For example, bilateral pneumonia which is present in both lungs, commonly known as double pneumonia.
Bile:  A yellow-green fluid that is made by the liver, stored in the gallbladder and passes through the common bile duct into the duodenum where it helps digest fat. The principal components of bile are cholesterol, bile salts, and the pigment bilirubin. An imbalance between these components of bile -- cholesterol, bile salts, and bilirubin -- leads to the formation of gallstones. Cholesterol is normally kept in liquid form by the dissolving action of the bile salts; an increased amount of cholesterol in the bile overwhelms the dissolving capacity of the bile salts and leads to the formation of cholesterol gallstones. Similarly, a deficiency of bile salts promotes cholesterol gallstone formation.
Bile acid:  An acid made by the liver that works with bile to break down fats. On a more technical level, bile acids are steroid carboxylic acids derived from cholesterol.
Bile acid resin:  Bile acid resins are substances that bind in the intestines with bile acids that contain cholesterol and are then eliminated in the stool. The major effect of bile acid resins is to lower LDL-cholesterol by about 10 to 20 percent. Small doses of resins can produce useful reductions in LDL-cholesterol. Bile acid resins are sometimes prescribed with a statin for patients with heart disease to increase cholesterol reduction. When these two drugs are combined, their effects are added together to lower LDL-cholesterol by over 40 percent. Cholestyramine (brand name: QUESTRAN) and colestipol (COLESTID) are the two main bile acid resins currently available. This is a primitive way of dealing with an imaginary problem; nevertheless it is used.
Bile duct cancer:  An uncommon type of cancer that arises from the bile duct, the tube that connects the liver and the gallbladder to the small intestine. The symptoms of bile duct cancer include yellowing of the skin (jaundice), pain in the abdomen, fever, and itching.
Bile sludge:  A mixture of microscopic particulate matter in bile that occurs when particles of material precipitate from bile. (Bile is the fluid that is made by the liver. It is stored in the gallbladder until after a meal when it passes out of the gallbladder and through the common bile duct into the intestine to help digest fat in the meal.) The composition of biliary sludge varies. The most common particulate components of biliary sludge are cholesterol crystals and calcium salts. Biliary sludge has been associated with certain conditions including rapid weight loss, fasting, pregnancy, medications (ceftriaxone, octreotide), and bone marrow or solid organ transplantation although it most commonly occurs in individuals with no identifiable condition. Biliary sludge can be looked upon as a condition of microscopic gallstones, although it is not clear at what size the particles in biliary sludge should be considered gallstones.
Bilharzia:  A parasitic disease of humans, also called schistosomiasis. Three main species of these trematode worms (flukes)--Schistosoma haematobium, S. japonicum, and S. mansoni — cause disease in humans. The disease is acquired from infested water. Also called Bilharziasis.
Biliary:  Having to do with the gallbladder, bile ducts, or bile. The biliary system itself consists of the gallbladder and bile ducts and, of course, the bile.
Biliary atresia:  Congenital absence or closure of the major bile ducts, the ducts that drain bile from the liver. Biliary atresia results in a progressive inflammatory process which may lead to cirrhosis of the liver. The infant looks normal at birth but develops jaundice after the age of 2 to 3 weeks with yellowing of the eyes and skin, light-colored stools and dark urine caused by the build up of the pigment called bilirubin in the blood. The abdomen may be swollen with a firm, enlarged liver. Weight loss and irritability develop as the jaundice increases. There is one case of biliary atresia out of every 15,000 live births. Females are affected slightly more often than males.
Biliary sand:  Biliary sand is a term mostly used by surgeons when they remove the gallbladder to describe uncountable, small particles in bile that are visible to the naked eye. Biliary sand may be looked upon as a stage in the growth of the particles that comprise sludge (which are microscopic and not visible to the naked eye) and gallstones, which are large enough to be counted easily. The composition of biliary sand varies but is similar to the composition of gallstones. The most common components of biliary sand are cholesterol crystals and calcium salts. Biliary sand may cause no symptoms or cause intermittent symptoms.
Biliary sludge:  A mixture of microscopic particulate matter in bile that occurs when particles of material precipitate from bile (see bile sludge above).
Bilious:  The adjective for bile, bilious has three meanings. It means of or relating to bile. By extension, bilious means suffering from liver dysfunction (and especially excessive secretion of bile). And, further by extension, it is indicative of a peevish ill-natured disposition.
Bilirubin:  A yellow-orange compound produced by the breakdown of hemoglobin from red blood cells. Measured in the blood as one way of detecting liver dysfunction.
Binaural:  Relating to both ears. From the Latin bini, a pair, + auris, ear = a pair (of) ears = both ears. Synonymous with stereophonic. While hearing aids may be binaural (in both ears) or monaural (in just one ear), binaural aids are generally considered to be superior.
Binge drinking:  The dangerous practice of consuming large quantities of alcoholic beverages in a single session. Binge drinking carries a serious risk of harm, including alcohol poisoning.
Binge eating disorder:  An eating disorder characterized by periods of extreme over-eating, but not followed by purging behaviors as in most cases of bulimia. Binge eating can occur alone, or in conjunction with a lesion of the hypothalamus gland, Prader-Willi disorder, or other conditions. It can contribute to high blood pressure, weight gain, diabetes, and heart disease. Treatment depends on the patient and the underlying disorder, but may include therapy, dietary education and advice, and medication. In the church this is an example of a more general sin called gluttony. In medicine we try to remove the concept of personal responsibility for "disorders."
Binocular:  With both eyes, as in binocular vision.
Binocular diplopia:  Double vision (diplopia) that is only evident when looking through both eyes and disappears if one eye is closed or covered. The condition is caused by misalignment of the eyes by the extraocular muscles (the muscles around the eyeball that control gaze). This may be due to strabismus (misalignment of the eyes from birth), neurologic damage to the extraocular muscles (as from a brain abscess, stroke, head trauma or brain tumor), diabetes, myasthenia gravis, Graves disease, or trauma to the eye muscles, as from a fracture of the orbit.
Binocular vision:  The ability to maintain visual focus on an object with both eyes, creating a single visual image. Lack of binocular vision is normal in infants. Adults without binocular vision experience distortions in depth perception and visual estimation of distance.
Binswanger disease:  A form of dementia with blood vessel abnormalities in the deep white-matter of the brain causing loss of memory, decreasing cognition, and mood changes.
Bioactive:  Having an effect upon a living organism, tissue, or cell. Biologically active. Antibiotic, enzymes, and vitamins are all bioactive substances.
Biochemistry:  The chemistry of biology, the application of the tools and concepts of chemistry to living systems. Biochemists study such things as the structures and physical properties of biological molecules, including proteins, carbohydrates, lipids, and nucleic acids; the mechanisms of enzyme action; the chemical regulation of metabolism; the chemistry of nutrition; the molecular basis of genetics (inheritance); the chemistry of vitamins; energy utilization in the cell; and the chemistry of the immune response.
Bioelectric impedance analysis:  A seemingly simple method for determining the lean body mass. Abbreviated BIA. There are two methods of the BIA. One involves standing on a special scale with footpads. A harmless amount of electrical current is sent through the body, and then the percentage of body fat is calculated. The other type of BIA involves electrodes usually placed on a wrist and an ankle and on the back of the right hand and on the top of the foot. The change in voltage between electrodes is measured. The person's body fat percentage is then calculated from the results of the BIA. These techniques are notoriously inaccurate. Measurement of bouyancy in water is the gold standard for measuring lean body mass. Extreme athletes can be at around 2-3% body fat. The average person is around 16%. (Mine is 7%; not bad, huh?)
Biofeedback:  A method of treatment that uses monitors to feed back to patients physiological information of which they are normally unaware. By watching the monitor, patients can learn by trial and error to adjust their thinking and other mental processes in order to control "involuntary" bodily processes such as blood pressure, temperature, gastrointestinal functioning, and brain wave activity.
Biofilm:  An aggregate of microbes with a distinct architecture. A biofilm is like a tiny city in which microbial cells, each only a micrometer or two long, form towers that can be hundreds of micrometers high. The "streets" between the towers are really fluid-filled channels that bring in nutrients, oxygen and other necessities for live biofilm communities. Biofilms form on the surface of catheter lines and contact lenses. They grow on pacemakers, heart valve replacements, artificial joints and other surgical implants. The CDC (Centers for Disease Control) estimate that over 65% of nosocomial (hospital-acquired) infections are caused by biofilms. Bacteria growing in a biofilm are highly resistant to antibiotics, up to 1,000 times more resistant than the same bacteria not growing in a biofilm. Standard antibiotic therapy is often useless and the only recourse may be to remove the contaminated implant. Fungal biofilms also frequently contaminate medical devices. They cause chronic vaginal infections and lead to life-threatening systemic infections in people with hobbled immune systems. Biofilms are involved in numerous diseases. For instance, cystic fibrosis patients have Pseudomonas infections that often result in antibiotic resistant biofilms.
Bioinformatics:  The sum of the computational approaches to analyze, manage, and store biological data. Bioinformatics involves the analysis of biological information using computers and statistical techniques, the science of developing and utilizing computer databases and algorithms to accelerate and enhance biological research. formatics is used in analyzing genomes, proteomes (protein sequences), three-dimensional modeling of biomolecules and biologic systems, etc. Training in informatics requires backgrounds in molecular biology and computer science, including database design and analytical approaches.
Biological response modifiers (BRMs):  Substances that stimulate the body's response to infection and disease. The body naturally produces small amounts of these substances. Scientists can produce some of them in the laboratory in large amounts for use in treating cancer, rheumatoid arthritis, and other diseases. BMRs used in biological therapy include monoclonal antibodies, interferon, interleukin-2 (IL-2), and several types of colony stimulating factors (CSF, GM-CSF, G-CSF). Interleukin-2 and interferon are BRMs being tested for the treatment of advanced malignant melanoma. Interferon is a BRM now in use to treat hepatitis C. The side effects of BRM therapy often include flu-like symptoms such as chills, fever, muscle aches, weakness, loss of appetite, nausea, vomiting, and diarrhea. Some patients develop a rash, and some bleed or bruise easily. Interleukin therapy can cause swelling. Depending on the severity of these problems, patients may need to stay in the hospital during treatment.
Biological therapy:  Treatment to stimulate or restore the ability of the immune (defense) system to fight infection and disease. Biological therapy is thus any form of treatment that uses the body's natural abilities that constitute the immune system to fight infection and disease or to protect the body from some of the side effects of treatment. We use biological therapy extensively in nutritional medicine.
Biomarker:  A biochemical feature or facet that can be used to measure the progress of disease or the effects of treatment.
Biopsy:  The removal of a sample of tissue for purposes of diagnosis. (Many definitions of "biopsy" stipulate that the sample of tissue is removed for examination under a microscope. This may or may not be the case. The diagnosis may be achieved by other means such as by analysis of chromosomes or genes.)
Biotechnology:  The fusion of biology and technology. Biotechnology is the application of biological techniques to product research and development. In particular, biotechnology involves the use by industry of recombinant DNA, cell fusion, and new bioprocessing techniques. Biotechnology is expected to become increasingly important in the 21st century.
Bioterrorism:  Terrorism using biologic agents. Biological diseases and the agents that might be used for terrorism have been listed by the US Centers for Disease Control and Prevention (the CDC). The list includes a sizable number of "select agents" -- potential weapons whose transfer in the scientific and medical communities is regulated to keep them out of unfriendly hands. These "select agents" are very varied. They comprise viruses, bacteria, rickettsiae (micro-organisms that have traits common to both bacteria and viruses), fungi and biological toxins.
Biotherapy:  Treatment to stimulate or restore the ability of the immune (defense) system to fight infection and disease. Biological therapy is thus any form of treatment that uses the body's natural abilities that constitute the immune system to fight infection and disease or to protect the body from some of the side effects of treatment.
Biotin:  A water-soluble B-complex vitamin involved in carbon dioxide transfer and therefore essential to the metabolism of carbohydrate and fat. A balanced diet usually contains enough biotin. Foods with high biotin levels include nuts, cereals, green leafy vegetables and milk. Biotin deficiency, which is characterized by hair loss and a scaly red rash, can occur with prolonged intravenous feeding or the frequent consumption of raw egg whites which contain a biotin antagonist called avidin. Biotin supplementation is recommended during pregnancy because the biotin requirement rises during pregnancy and a substantial number of pregnant women become biotin depleted. Extra biotin is also needed during long-term anticonvulsant treatment which depletes biotin.
Bipolar disorder:  A form of depressive disease that characteristically involves cycles of depression and elation or mania. Sometimes the mood switches from high to low and back again are dramatic and rapid, but more often they are gradual and slow. Both phases of the disease are deleterious. Mania affects thinking, judgment, and social behavior in ways that may cause serious problems and embarrassment. For example, unwise business or financial decisions may be made when an individual is in a manic phase. Depression can also affect thinking, judgment, and social behavior in ways that may cause grave problems. For example, it raises the risk of suicide. Bipolar disorder is not as prevalent as some other forms of depressive disorders but it is often a chronic recurring condition. Also called manic-depressive illness and manic-depression.
Birt-Hogg-Dube syndrome:  An inherited condition in which benign tumors develop in hair follicles on the head, chest, back, and arms. These tumors are called fibrofolliculomas. Other characteristic skin abnormalities are trichodiscomas and acrochordons. A trichodiscoma is a tumor of the hair disc while an acrochordon is a skin tag. People with this syndrome are at increased risk for developing colon or kidney cancer as well as spontaneous pneumothorax due to lung cysts. It is inherited in an autosomal dominant manner.
Birth defect:  Any defect present in a baby at birth, irrespective of whether the defect is caused by a genetic factor or by prenatal events that are not genetic.
Birth rate:  The birth rate is usually given as the number of live births divided by the average population (or the population at midyear). This is termed the crude birth rate. In 1995, for example, the crude birth rate per 1,000 population was 14 in the United States, 16.9 in Australia, etc.
Birthmark:  A persistent visible mark on the skin that is evident at birth or shortly thereafter. A birthmark is often due to a nevus (a mole) or an hemangioma (a localized collection of small blood vessels). Birthmarks that are pink or red are commonly capillary hemangiomas - collections of tiny blood vessels - that are most evident when the baby cries. Common locations are on the midforehead, the eyelids, just above the nose, between the nose and the upper lip, and the so-called "stork bite" on the nape of the neck. These marks generally become harder to see or disappear entirely within a few years. A special instance of hemangioma is called the "port wine stain." You may recall that Mikhail Gorbachev has a port wine stain on his head and forehead.
bis in die (on prescription):  Seen on a prescription, bid means twice (two times) a day. It is an abbreviation for "bis in die" which in Latin means twice a day. The abbreviation bid is sometimes written without a period either in lower-case letters as "bid" or in capital letters as "BID" or with periods as "b.i.d."
Bisexual:  An individual who engages in both heterosexual and homosexual sexual relations. Bisexual can also refer to the corresponding lifestyle.
Bisexual suicide risk:  High rates of suicide have consistently been reported among homosexuals, particularly among adolescents and young adults. A 1989 report concluded that "gay youth are 2 to 3 times more likely to attempt suicide than other young people. They may comprise up to 30% of completed youth suicides annually." In 1999 it was reported in two independent studies (one of twins in the U.S. and the other with 21-year follow-up in New Zealand) that homosexual and bisexual men and women are at greater risk of suicidal ideation and overall mental health problems than their heterosexual counterparts.
Bisphenol A:  Bisphenol A, commonly abbreviated as BPA, is an organic compound with two phenol functional groups. It is a difunctional building block of several important plastics and plastic additives. With an annual production of 2–3 million metric tonnes, it is an important monomer in the production of polycarbonate. Suspected of being hazardous to humans since the 1930s, concerns about the use of bisphenol A in consumer products were regularly reported in the news media in 2008 after several governments issued reports questioning its safety, and some retailers have removed products made of it from their shelves. Stucies whow that women with elavated levels of bisphenol are three times more likely to have a miscarriage than those with low levels.
Bisphosphonate:  A class of drugs used to strengthen bone. Bone is in a constant state of remodeling, whereby new bone is laid down by cells called osteoblasts while old bone is removed by cells called osteoclasts. Bisphosphonates inhibit bone removal (resorption) by the osteoclasts. Bisphosphonates are used to treat osteoporosis and the bone pain from diseases such as metastatic breast cancer, multiple myeloma, and Paget's disease. The bisphosphonates include Fosamax (alendronate) and Aredia (pamidronate). I prefer to treat osteoporosis by replacement of declining bio-identical hormones, oral supplementation, and if necessary regeneration of digestive functions.
BKA:  Acronym standing for "below knee amputation." A nurse scrubbing for a BKA is preparing to assist in a below-knee amputation. BKA is as opposed to AKA (above knee amputation).
Black Death:  The Medieval black plague that ravaged Europe and killed a third of its population. It was due to the plague which is caused by a bacterium (Yersinia pestis) transmitted to humans from infected rats by the oriental rat flea. In 14th-century Europe, the victims of the Black Death had bleeding below the skin (subcutaneous hemorrhage) which darkened ("blackened") their bodies. The Black Death was characterized by gangrene of the fingers, toes, and nose. DNA tests on 600-year-old teeth from victims of the Black Death have confirmed that Yersinia pestis was the cause of the Black Death.
Black henna:  A tattoo ink and paste consisting of henna ( a coloring made from the leaves of the Egyptian privet, Lawsonia inermis) with other ingredients added, sometimes including para-phenylenediamine, (PPD). Allergic reactions to PPD include a red rash, contact dermatitis, itching, blisters, open sores, scarring of the skin and other potentially harmful effects. Allergic reactions to PPD may also lead to sensitivity to other products such as hair dye, sun block and some types of black clothing. Also called blue henna.
Black lung disease:  A chronic occupational lung disease contracted by the prolonged breathing of coal mine dust. The silica and carbon in the coal dust cause black lung disease. About one of every 20 miners studied in the US has X-ray evidence of black lung disease, a form of pneumoconiosis. In its early stages, called simple pneumoconiosis, the disease does not prevent the miner from working or carrying on most normal activities. In some miners, the disease never becomes more severe. In other miners, the disease progresses from simple to complicated pneumoconiosis, a condition also called progressive massive fibrosis. Pneumoconiosis is not reversible. There is no specific treatment. Black lung disease has gone by many names, including anthracosis, black lung, black spittle, coal worker's pneumoconiosis, miner's asthma, and silicosis.
Black plague:  In 14th-century Europe, the victims of the "black plague" had bleeding below the skin (subcutaneous hemorrhage) which made darkened ("blackened") their bodies. Black plague can lead to "black death" characterized by gangrene of the fingers, toes, and nose. Black plague is caused by a bacterium (Yersinia pestis) which is transmitted to humans from infected rats by the oriental rat flea.
Bladder:  The organ that stores urine. The bladder is a hollow organ in the lower abdomen. The kidneys filter waste from the blood and produce urine, which enters the bladder through two tubes called ureters. Urine leaves the bladder through another tube, the urethra. In women, the urethra is a short tube that opens just in front of the vagina. In men, it is longer, passing through the prostate gland and then the penis.
Bladder cancer:  A common form of cancer that begins in the lining of the bladder as a superficial tumor (carcinoma in situ). The most common warning sign is blood in the urine. If there is enough blood to color the urine it may range from slightly rusty to deep red. Other symptoms may be pain during urination and frequent urination or feeling the need to urinate without results.
Blade bone:  Familiar term for the scapula, also called the shoulder blade or wing bone, the flat triangular bone at the back of the shoulder.
Blast phase:  Refers to advanced chronic myelogenous leukemia. In this phase, the number of immature, abnormal white blood cells in the bone marrow and blood is extremely high. Also called blast crisis.
Blastocyst:  A thin-walled hollow structure in early embryonic development that contains a cluster of cells called the inner cell mass from which the embryo arises. The outer layer of cells gives rise to the placenta and other supporting tissues needed for fetal development within the uterus while the inner cell mass cells gives rise to the tissues of the body.
Blastocystosis:  Infection with Blastocystis hominis, a common microscopic parasite found worldwide. Symptoms may include watery or loose stools, diarrhea, abdominal pain, anal itching, weight loss, and excess gas. Some people have no symptoms. The organism can remain in the intestines for weeks, months, or years. Diagnosis requires finding it in the stool, How Blastocystis is transmitted is unknown, although the number of people infected seems to increase in areas where sanitation and personal hygiene is inadequate. Treatment is with the antibiotics metronidazole or iodoquinol.
Blastoma:  A tumor thought to arise in embryonic tissue. The term "blastoma" is commonly used as part of the name for a tumor as, for examples, in glioblastoma and medulloblastoma (types of brain tumors), hepatoblastoma (a liver tumor), nephroblastoma ( Wilms tumor of the kidney), neuroblastoma (a childhood tumor of neural origin), osteoblastoma (a bone tumor) and retinoblastoma (a tumor of the retina).
Blastomycosis:  Infection with a fungus called Blastomyces dermatitidis. The infection causes symptoms in about 50% of cases. It usually presents as a flu-like illness with fever, chills, productive cough, myalgia, arthralgia and pleuritic chest pain. Some patients fail to recover and develop chronic pulmonary infection or widespread disseminated infection (affecting the skin, bones, and genitourinary tract). It occasionally affects the meninges which cover the brain and spinal cord. The offending fungus is found in moist soil enriched with decomposing organic debris. It is endemic in parts of the south-central, south-eastern and mid-western United States and in microfoci in Central and South America and parts of Africa. Transmission of the fungus is by inhalation of airborne conidia (spores) after disturbance of contaminated soil.
Blasts:  Immature blood cells. Leukemic blasts do not grow and age normally; they proliferate wildly and fail to mature.
Bleb:  A bag-like structure more than 5 mm in diameter with thin walls that may be full of fluid. Also called a bulla.
Blepharitis:  Inflammation of the eyelids.
Blepharophimosis:  Horizontal narrowing of the palpebral fissures (eye slits).
Blepharoplasty:  Plastic surgery on the eyelids. Blepharoplasty may be done to correct ptosis (sagging eyelids), remove fatty bulges around the eyes, and eliminate hanging skin from the eyelids.
Blepharospasm:  Involuntary forcible closure of the eyelids. The first symptom may be uncontrollable blinking. Only one eye may be affected initially, but eventually both eyes are usually involved. The spasms may leave the eyelids completely closed causing functional blindness even though the eyes and vision are normal. Blepharospasm is a form of focal dystonia.
Blighted ovum:  A fertilized ovum (egg) that did not develop or whose development ceased at an early stage, before 6 or 7 weeks of gestation. On the ultrasound examination of a blighted ovum, only the gestational sac that normally surrounds the embryo can be seen. There is usually no embryo inside the gestational sac. A blighted ovum is a form of early spontaneous abortion (miscarriage).
Blind spot: In ophthalmology, a blind spot is:
(1) a small area of the retina where the optic nerve enters the eye; this type of blind s:  
Blinded study:  A study done in such a way that the patients or subjects do not know (are blinded as to) what treatment they are receiving to ensure that the results are not affected by a placebo effect (the power of suggestion). In a double-blind study the investigators as well as the subjects do not know the treatment.
Blindness:  Loss of useful sight. Blindness can be temporary or permanent. Damage to any portion of the eye, the optic nerve, or the area of the brain responsible for vision can lead to blindness. There are numerous (actually, innumerable) causes of blindness. The current politically correct terms for blindness include visually handicapped and visually challenged.
Blister:  A collection of fluid underneath the top layer of skin (epidermis). One that is more than 5 mm in diameter with thin walls and is full of watery fluid is called a bulla or a bleb. There are many causes of blisters including burns, vesicant agents, friction forces, and diseases of the skin. There are a number of types of blisters, including: Blood blister - a blister full of blood due to a pinch, bruise or repeated friction. Water blister - a blister with clear watery contents that is not purulent (does not contain pus) and is not sanguineous (does not contain blood). Fever blister - a blister in the mouth or around it that causes pain, burning, or itching before bursting and crusting over. It is due to the herpes simplex virus which is latent (dormant in the body) and can be reawakened (reactivated) by such factors as stress, sunburn, or fever. Hence, it called a fever blister or a cold sore.
Blood cleaner:  A process designed to eliminate most pathogens - viruses, bacteria and fungi - from donated blood. The process is termed "pathogen inactivation." It depends upon the fact that three components of blood that are given in transfusions - red blood cells to carry oxygen, platelets to help blood clot and plasma for clotting and other purposes - do not contain DNA or RNA, the basic genetic materials of life, whereas viruses, bacteria and fungi do. Therefore inactivating DNA or RNA can selectively kill these pathogens while leaving the blood itself unharmed.
Blood clot:  Blood that has been converted from a liquid to a solid state. Also called a thrombus. Blood clots within blood vessels are occasional but serious side effects of estrogen therapy. They are dose-related, that is, they occur more frequently with higher doses of estrogen,particularly of synthetic estrogen.
Blood count:  The calculated number of white or red blood cells (WBCs or RBCs) in a cubic millimeter of blood.
Blood culture:  A test designed to detect if microorganisms such as bacteria and fungi are present in blood. A sample of blood obtained using sterile technique is placed in a culture media and incubated in a controlled environment for 1 to 7 days. If microorganisms grow, they can be identified as to type and tested against different antibiotics for proper treatment of the infection. Because microorganisms may only be intermittently present in blood, a series of 3 blood cultures is usually done before the result is considered negative.
Blood dyscrasia:  Blood disease in which the cells are not in proper proportion. (dys+crasia = bad mix)
Blood group:  An inherited feature on the surface of the red blood cells. A series of related blood types constitute a blood group system such as the Rh or the ABO system. In the US, the most common type is O+ which is present in 37.4% of the population. The frequencies in descending order are O+ (37.4%), A+ (35.7%), B+ (8.5%), O- (6.6%), A- (6.3%), AB+ (3.4%), B- (1.5%) and AB- (0.6%). A person can be A, B, AB, or O. If a person has two A genes, their red blood cells are type A. If a person has two B genes, their red cells are type B. If the person has one A and one B gene, their red cells are type AB. If the person has neither the A nor B gene, they are type O. The situation with antibodies in blood plasma is just the opposite of the red cell antigen types. Someone with type A red cells has anti-B antibodies (directed against type B red cells) in their blood. Someone with type B red cells has anti-A antibodies in plasma. Someone who is type O has both anti-A and anti-B antibodies in plasma. And someone who is type AB has neither anti-A nor anti-B antibodies in plasma.
Blood pH:  The acidity or alkalinity of blood. The pH of any fluid is the measure of the hydrogen ion (H-) concentration. A pH of 7 is neutral. The lower the pH, the more acidic the blood. A variety of factors affect blood pH including what is ingested, vomiting, diarrhea, various chronic infections, lung function, endocrine function, kidney function, and urinary tract infection. Normal blood pH is tightly regulated between 7.25 and 7.45.
Blood poisoning:  The medical term is "septicemia." This is a (systemic) disease that is due to the presence and the persistence of germs (pathogenic microorganisms) or their toxins in the bloodstream.The "germs" can be bacteria (in bacteremia) or any other microscopic agent of infection capable of causing disease in humans. Another term that is very closely related to "blood poisoning" and "septicemia" is "sepsis." "Sepsis" also refers to the presence and persistence of germs or their toxins in the blood but those germs or toxins do not need to be in the blood. They may be in other tissues of the body. Blood poisoning/septicemia and sepsis are often serious. They can sometimes be life threatening diseases calling for urgent and comprehensive care.
Blood pressure:  The blood pressure is the pressure of the blood within the arteries. It is produced primarily by the contraction of the heart muscle and is modulated by the expansibility of the vascular system (which is decreased in arteriosclerosis). It is recorded by two numbers. The first (systolic pressure) is measured after the heart contracts and is highest. The second (diastolic pressure) is measured before the heart contracts and lowest. A blood pressure cuff is used to measure the pressure. Elevation of blood pressure is called "hypertension."
Blood pressure, high:  Also known as hypertension, high blood pressure is, by definition, a repeatedly elevated blood pressure exceeding 140 over 90 mmHg - a systolic pressure above 140 with a diastolic pressure above 90. Chronic hypertension is a "silent" condition. It can cause blood vessel changes in the back of the eye (retina), abnormal thickening of the heart muscle, kidney failure, and brain damage. For diagnosis, there is no substitute for measurement of blood pressure. No specific cause for hypertension is found in 95% of cases. High blood pressure is treated with regular aerobic exercise, weight reduction (if overweight), salt restriction, and medications.
Blood pressure, low:  Any blood pressure that is below the normal expected for an individual in a given environment. Low blood pressure is also referred to as hypotension. Low blood pressure is a relative term because the blood pressure normally varies greatly with activity, age, medications, and underlying medical conditions. Low blood pressure can result from conditions of the nervous system, conditions that do not begin in the nervous system, and drugs. Neurologic conditions that can lead to low blood pressure include changing position from lying to more vertical (postural hypotension), stroke, shock, lightheadedness after urinating or defecating, Parkinson's disease, neuropathy and simply fright. Nonneurologic conditions that can cause low blood pressure include bleeding, infections, dehydration, heart disease, adrenal insufficiency, pregnancy, prolonged bed rest, poisoning, toxic shock syndrome, and blood transfusion reactions. Hypotensive drugs include blood pressure drugs, diuretics (water pills), heart medications (especially calcium antagonists-nifedipine/PROCARDIA, beta blockers-propranolol/INDERAL and others), depression medications (such as amitriptyline/ELAVIL), and alcohol.
Blood sugar, high:  An elevated level of the sugar glucose in the blood. Also called hyperglycemia. High blood sugar is a finding in a number of conditions, most notably diabetes mellitus. Elevated blood glucose leads to spillage of glucose into the urine (glucosuria) so that the urine is sugary. (The term diabetes mellitus means "sweet urine.") Aside from diabetes, the many other causes of high blood sugar include just eating more sugar (or food) than usual, the presence of an infection or another illness, an injury and the stress of surgery. High blood sugar may produce few or no symptoms. When there are symptoms, they may be dry mouth, thirst, frequent urination, urination during the night, blurry vision, fatigue or drowsiness, weight loss, or increased appetite. An elevated level of blood sugar may be a useful independent indicator of heart disease risk. The risk of dying from heart disease has been found to rise as the level of blood glucose increases (regardless of age, weight, blood pressure, cholesterol and smoking status).
Blood transfusion:  The transfer of blood or blood components from one person (the donor) into the bloodstream of another person (the recipient). This may be done as a lifesaving maneuver to replace blood cells or blood products lost through bleeding. Transfusion of your own blood (autologous) is the safest method but requires advance planning and not all patients are eligible. Directed donor blood allows the patient to receive blood from known donors. Volunteer donor blood is usually most readily available and, when properly tested has a low incidence of adverse events. Blood conserving techniques are an important aspect of limiting transfusion requirements.
Blood urea nitrogen (BUN):  A measure primarily of the urea (a byproduct of muscle metabolism) level in blood. Urea is cleared by the kidney. Diseases that compromise the function of the kidney frequently lead to increased blood levels.
Blood-brain barrier:  A protective network of blood vessels and cells that filters blood flowing to the brain.
Blood-thinner:  A common name for an anticoagulant agent used to prevent the formation of blood clots. Blood-thinners do not really thin the blood. They prevent it from clotting. Blood-thinners (anticoagulants) have various uses. Some are used for the prophylaxis (prevention) of thromboembolic disorders; others are used for the treatment of thromboembolism. Commonly used blood thinners are Heparin and Coumadin.
Bloody nose:  The nose is rich in blood vessels and situated in a vulnerable position on the face. As a result, any trauma to the face can cause bleeding which may be profuse. Nosebleeds can occur spontaneously when the nasal membranes dry out, crust, and crack, as is common in dry climates, or during the winter months when the air is dry and warm from household heaters. People are more susceptible if they are taking medications which prevent normal blood clotting (Coumadin, heparin, warfarin, aspirin, or any anti-inflammatory medication). Other predisposing factors include infection, trauma, allergic and non-allergic rhinitis, hypertension, alcohol abuse, and inherited bleeding problems. To stop a nosebleed, you should: 1. Pinch all the soft parts of the nose together between your thumb and index finger. 2. Press firmly toward the face - compressing the pinched parts of the nose against the bones of the face. 3. Hold the nose for at least 5 minutes (timed by the clock). Repeat as necessary until the nose has stopped bleeding. 4. Sit quietly, keeping the head higher than the level of the heart; that is, sit up or lie with the head elevated. Do not lay flat or put your head between your legs. 5. Apply ice (crushed in a plastic bag or washcloth) to nose and cheeks. Styptic powder is used by veterinarians to stop the bleeding in animals. It is available under the name Kwik Stop. It should be used only for rare instances of bleeding as it contains aluminum. Frequent dosing could cause aluminum poisoning. It is best applied with a Q-tip. It is for veterinary use only.
Bloody show:  A term unsed in child birth medicine (obstetrics) which denotes a classic sign of impending labor. It consists of blood-tinged mucus created by extrusion and passage of the mucous plug that filled the cervical canal (the canal between the vagina and uterus) during pregnancy. The same term, bloody show, can be applied to the beginning of menstruation.
Bloody sputum:  Spitting up blood or bloody mucus. Bloody sputum can come from common forms of infection in the lungs and airways, such as acute bronchitis or pneumonia. Whenever bloody sputum is present and cannot be attributed to one of these curable conditions, a complete lung evaluation is warranted, including bronchoscopy. One possible cause is lung or bronchial cancer. Bloody sputum is also referred to as hemoptysis. literally blood cough.
Blue baby:  A baby who is cyanotic (blue), due usually to a heart malformation that prevents the baby's blood from being fully oxygenated. The bluish color reflects the deoxygenated state of the blood. (Oxygenated blood is red.) Sometimes the term "blue baby" is also applied to a child who is cyanotic due to failure by the lungs to oxygenate the blood.
Blue baby operation:  A surgical procedure for a baby who is cyanotic (blue) due to a heart malformation that prevents blood from being fully oxygenated. The surgery is designed to palliate or ideally correct the heart defect and relieve the cyanosis.
Blunted affect:  A severe reduction in emotional expressiveness. People with depression and schizophrenia often show blunted affect. A person with schizophrenia may not show the signs of normal emotion, may speak in a monotonous voice, have diminished facial expressions, and appear extremely apathetic. Also known as flat affect.
Blurred vision:  This occurs when the image of the outside world is not correctly focused on the retina. If the image focuses in front of the retina, this is called nearsightedness (or myopia) and is caused by an eyeball which is too long in relationship to the thickness of the lens of the eys. If the image focuses behind the retina, this is called farsightedness (or hyperopia) and is caused by an eyball which is too short in relationship to the thickness of the lens of they eye. Close-up vision can alwo be blurred by presbyopia (literally old vision), an inability to focus on a close object (accomodate). This occurs as the eye ages, usually beginning in the 40s.
Blush:  A redness of the skin, typically over the cheeks or neck. A blush is usually temporary and brought on by excitement, exercise, fever, or embarrassment. Blushing is an involuntary response of the nervous system leading to widening of the capillaries of the involved skin. Also referred to as a flush.
BMD (bone mass density):  Abbreviation for bone mass density and the synonymous term, bone mineral density. Bone mass density is a measure of bone density. Loss of bone mass is due to osteopenia (literally poor bone) or, if more severe, to osteoporosis (literally porous bone).
BMI (body mass index):  A key index for relating a person's body weight to their height. The body mass index (BMI) is a person's weight in kilograms (kg) (one pound = 0.45 kilos) divided by their height in meters (m) (one meter = 39.37 inches) squared. The National Institutes of Health (NIH) now defines normal weight, overweight, and obesity according to the BMI rather than the traditional height/weight charts. Since the BMI describes the body weight relative to height, it correlates strongly (in adults) with the total body fat content. Overweight is defined as a BMI of 27.3 % or more for women and 27.8 % or more for men, according to the NIH. Obesity is defined as a BMI of 30 and above, according to the NIH. (A BMI of 30 is about 30 pounds overweight.) Note, however, that some very muscular people may have a high BMI without undue health risks.
BMP (bone morphogenetic protein):  A member of a family of proteins that promote the formation of bone and the skeleton and help mend broken bones. Although it was known that scrapings from healthy bone stimulated the healing of fractures, the nature of the regenerative mechanism remained a mystery until 1965 when Dr. Marshall Urist did an experiment in which he implanted demineralized, pulverized bone in a rabbit's muscle. Bone formed at the site. Dr. Urist called the protein responsible for this phenomenon "bone morphogenetic protein" (BMP).
BMT (Bone marrow transplantation):  a procedure in which doctors replace bone marrow that is diseased (or damaged) with healthy bone marrow. The bone marrow to be replaced may be deliberately destroyed by high doses of chemotherapy and/or radiation therapy. The replacement marrow may come from another person, or it may be the patient's own marrow (which was removed and stored before treatment). When marrow from an unrelated donor is used, the procedure is an allogeneic bone marrow transplantation. If the marrow is from an identical twin, it is termed syngeneic. Autologous bone marrow transplantation uses the patient's own marrow.
BNP (B-type natriuretic peptide):  A 32-amino-acid polypeptide secreted by the ventricles of the heart in response to excessive stretching of myocytes (heart muscles cells) in the ventricles. The levels of B-type natriuretic peptide (BNP) are elevated in patients with left ventricular dysfunction. BNP levels correlate with both the severity of symptoms and the prognosis in congestive heart failure. BNP levels are higher in patients with dyspnea (shortness of breath) due to heart failure than in patients with dyspnea from other causes. Rapid measurement of BNP in the emergency department therefore helps in the evaluation and treatment of patients with acute dyspnea and reduces the time to discharge and the cost of their treatment. BNP appears to be a useful marker of cardiovascular risk, even in people with no clinical evidence of cardiovascular disease. The levels of BNP predict the risk of heart failure, first cardiovascular events, atrial fibrillation, and stroke or transient ischemic attack.
BOD POD:  A method for determining the lean body mass. The BOD POD is a computerized, egg-shaped chamber. Using the same whole-body measurement principle as underwater weighing, the BOD POD measures a subject's mass and volume, from which their whole-body density is determined. Using these data, body fat and lean muscle mass can then be calculated.
Body dysmorphic disorder (BDD, somatoform disorder, dysmorphia, body image obsession):  A psychiatric disorder characterized by excessive preoccupation with imagined defects in physical appearance. People with body dysmorphic disorder are obsessed by the idea that some part of their body - hair, nose, skin, hips, whatever - is ugly or deformed, when in truth it looks normal. BDD may focus on moles, freckles, acne, minor scars, facial or body hair, or the size and shape of their breasts or genitalia. People with BDD may spend an excess of time looking in the mirror, be forever fixing their hair, or wear heavy makeup or sunglasses inside as a form of camouflage.
Body fat monitor (Bioelectric impedance analyzer):  A method for determining the lean body mass. There are two methods of the BIA. One involves standing on a special scale with footpads. A harmless amount of electrical current is sent through the body, and then the percentage of body fat is calculated. The other type of BIA involves electrodes usually placed on a wrist and an ankle and on the back of the right hand and on the top of the foot. The change in voltage between electrodes is measured. The person's body fat percentage is then calculated from the results of the BIA.
Body habitus:  The physique or body build.
Body hearing aid:  A type of hearing aid that comprises a rectangular case carried on the body connected by cords to earmolds. A body hearing aid are generally reserved for the most severe hearing losses.
Body mass index (BMI):  A key index for relating a person's body weight to their height. The body mass index is a person's weight in kilograms (kg) divided by their height in meters (m) squared.
Body type:  A somewhat old-fashioned term used to classify the human shape into three primary types: ectomorphic, mesomorphic, or endomorphic.
Boerhaave's syndrome:  Spontaneous tearing and rupture of the esophagus. Typically, Boerhaave's syndrome requires an operation for repair.
Bogorad's syndrome (Crocodile tears syndrome, gustatolacrimal reflex, paroxysmal lacrimation):  Spontaneous tearing in parallel with the normal salivation of eating. The crocodile tears syndrome occurs most often following facial paralysis when nerve fibers destined for a salivary gland are damaged and by mistake regrow into a tear gland. Named after the Russian neuropathologist who described the syndrome.
Boil:  A skin abscess, a collection of pus localized deep in the skin. A boil usually starts as a reddened, tender area and in time becomes firm and hard. Eventually, the center of the abscess softens and becomes filled with white blood cells that the body sends to fight the infection. This collection of white cells is the pus.
Bone:  Bone is the substance that forms the skeleton of the body. It is composed chiefly of calcium phosphate and calcium carbonate. It also serves as a storage area for calcium, playing a large role in calcium balance in the blood. The 206 bones in the body serve several other purposes. They support and protect internal organs (for example, the skull protects the brain and the ribs protect the lungs). Muscles pull against bones to make the body move. Bone marrow, the soft, spongy tissue in the center of many bones, makes and stores blood cells.
Bone cancer:  A malignancy in bone. Primary bone cancer, one that begins in bone, is uncommon but it is not unusual for a malignancy to spread to bone from other parts of the body such as from breast, lung, and prostate. The most common type of primary bone cancer is osteosarcoma, which develops in new tissue in growing bones. Another type of cancer, chondrosarcoma, arises in cartilage. Ewing's sarcoma, still another form of bone cancer, begins in immature nerve tissue in bone marrow. Osteosarcoma and Ewing's sarcoma tend to occur in children and adolescents, while chondrosarcoma occurs more often in adults. Cancers that metastasize to bone from another location are generally not called bone cancer but are named for the organ or tissue in which the cancer begins as, for example, lung cancer metastatic to bone.
Bone cyst, aneurysmal:  A benign lesion in a bone that contains connective tissue and blood inside a thin bony shell and that acts like a tumor and expands the bone. Aneurysmal bone cysts typically occur in the second decade of life and can affect any bone in the arms, legs, trunk or skull. Abbreviated ABC.
Bone cyst, simple:  A solitary fluid-filled cyst (cavity) in a bone, usually in the shaft of a long bone, especially the humerus, in a child. The cyst can cause pain in or near it. Also called a unicameral bone cyst or solitary bone cyst.
Bone density:  Bone density is the amount of bone tissue in a certain volume of bone. It can be measured using a special x-ray called a quantitative computed tomogram.
Bone marrow:  The soft blood-forming tissue that fills the cavities of bones and contains fat and immature and mature blood cells, including white blood cells, red blood cells, and platelets. Diseases or drugs that affect the bone marrow can affect the total counts of these cells.
Bone marrow aspiration:  The removal of a small amount of bone marrow (usually from the hip) through a needle. The needle is placed through the top layer of bone and a liquid sample containing bone marrow cells is obtained through the needle by aspirating (sucking) it into a syringe. The suction causes pain for a few moments. Bone marrow aspiration is done to diagnose and follow the progress of various conditions, including anemia and cancer, and to obtain marrow for transplantation.
Bone marrow biopsy:  The removal of a sample of bone marrow and a small amount of bone (usually from the hip) through a large needle. Two samples are taken. The first is bone marrow by aspiration (suction with a syringe). The second sample is a core biopsy to obtain bone marrow together with bone fibers. After the needle is removed, this solid sample is pushed out of the needle with a wire. Both samples are examined under a microscope to see the cells and architecture of the bone marrow.
Bone marrow transplant:  See above under "BMT."
Bone morphogenetic protein:  see above under "BMP."
Bone scan:  A technique to create images of bones on a computer screen or on film. A small amount of radioactive material is injected and travels through the bloodstream. It collects in the bones, especially in abnormal areas of the bones, and is detected by special instrument called a scanner. The image of the bones is recorded on a special film for permanent viewing. Bone scans are used for the detection and monitoring of disorders affecting the bones, including Paget's disease, cancer, infections, and fractures. Bone scanning is also helpful in evaluating joint diseases. Bone scanning can be used to detect and measure the activity of joint disease.
Bone type:  One of the four basic bone shapes in the human skeleton - long bones, short bones, flat bones, and irregular bones. Long bones have a tubular shaft and articular surface at each end. The major bones of the arms (humerus, radius, and ulna) and the legs (the femur, tibia, and fibula) are all long bones. Short bones also have a tubular shaft and articular surfaces at each end but are much smaller. The short bones include all of the metacarpals and phalanges in the hands, the metatarsals and phalanges in the feet, and the clavicle (collarbone). Flat bones are thin and have broad surfaces. The flat bones include the scapula (wingbone), the ribs, and the sternum (breastbone). Irregular bones are irregular in size and shape and are usually quite compact. They include the bones in the vertebral column, the carpal bones in the hands, tarsal bones in the feet, and the patella (kneecap).
Booster shot:  An additional dose of a vaccine needed periodically to "boost" the immune system. For example, a booster shot of the tetanus and diphtheria (Td) vaccine is recommended for adults every 10 years. (This author has his reservations about vaccines in general.)
Borage:  An herb, also known as the starflower, that has long been used for medicinal purposes. Borage (as borage oil) is rich in gamma linolenic acid (GLA), an essential fatty acid.
Borborygmi:  Rumbling sounds caused by gas moving through the intestines (stomach "growling"). Pronounced BOR-boh-RIG-mee. The singular is borborygmus.
Borderline personality disorder:  A mental illness characterized by pervasive instability in moods, interpersonal relationships, self-image, and behavior. This instability often disrupts family and work life, long-term planning, and the individual's sense of self-identity. Originally thought to be at the "borderline" of psychosis, people with borderline personality disorder (BPD) suffer from a disorder of emotion regulation. While less well known than schizophrenia or bipolar disorder (manic-depressive illness), BPD is more common, affecting 2% of adults, mostly young women. There is a high rate of self-injury without suicide intent, as well as a significant rate of suicide attempts and completed suicide in severe cases. Patients often need extensive mental health services and account for about 20% of psychiatric hospitalizations. Those who remain outside the mental health care system seek romantic relationships in which they are idolized in an attempt to assuage their extreme fear of abandonment. Fear of abandonment lies at the core of this illness and makes these individuals highly suspicious of those who care for them thus incapable of successful long-term relationships.
Bornholm disease:  Bornholm disease is a temporary illness that is a result of virus infection. The disease features fever and intense abdominal and chest pains with headache. The chest pain is typically worsened by breathing or coughing. The illness usually lasts from 3 to 14 days. The most common virus causing Bornholm disease is an enterovirus called Coxsackie B. Bornholm disease is also called epidemic myalgia and pleurodynia (because of inflammation of the lining tissue of the lungs).
Borrelia:  A group of bacteria that are helical spirochetes of the genus Borrelia. Some species of Borrelia cause relapsing fever in humans and animals. For example, Borrelia burgdorferi causes Lyme disease. Named after Amédée Borrel (1867-1936), French bacteriologist.
Botox:  A highly purified preparation of botulinum toxin A, a toxin produced by the bacterium Clostridium botulinum. Botox is for injection, in very small amounts, into specific muscles. It acts by blocking the transmission of nerve impulses to muscles and so paralyzing the muscles. Botox is a brand name that has passed into popular usage as a synonym for Botulinum toxin. Botox treatment has found a growing number of uses from easing muscle spasms (as, for example, in spastic cerebral palsy) to its increasingly widespread cosmetic use in flattening wrinkles.
Bottlefeeding:  The use of a substitute for breast milk for feeding infants. Pediatricians generally advise exclusively breastfeeding (that is, breastfeeding with no formula) for all full term, healthy infants for the first 6 months of life. However, many infants are formula-fed today, at least in part. For infants to achieve normal growth and maintain normal health, infant formulas must include proper amounts of water, carbohydrate, protein, fat, vitamins, essential fatty acids and minerals.
Botulism:  An uncommon but potentially very serious illness, a type of food poisoning, that produces paralysis of muscles, via a nerve toxin called botulinum toxin ("botox") that is manufactured by bacteria named Clostridium botulinum. There are various types of botulism, including: Food-borne botulism -- from eating food that contains the botulinum toxin. Wound botulism - caused by the toxin produced in a wound infected with the bacteria Clostridium botulinum. Infant intestinal botulism - when an infant consumes the spores of the bacteria, the bacteria grow in the baby's intestines and release toxin. Adult intestinal botulism - due to infection with Clostridium botulinum in adults, typically following abdominal surgical procedures. The symptoms of botulism can range from mild, including transient nausea and vomiting, to severe cases that progress to heart and lung failure and, sometimes, death. Food-borne botulism occurs typically in unrefrigerated or poorly refrigerated foods and foods without preservatives (especially uncooked or half-cooked meats).
Bovine:  Having to do with cows and cattle, as in bovine spongiform encephalopathy (mad cow disease), bovine tuberculosis, and bovine growth hormone.
Bovine tuberculosis:  Tuberculosis in cattle caused by infection with the bacterium Mycobacterium bovis which can be transmitted to other animals and to humans.
Bow-legs:  A condition in which the legs curve out to leave a gap between the knees after the period of infancy has passed. It can be corrected with surgery or casting. Also called genu varum and tibia vara.
Bowen's disease:  An early stage of skin cancer. It is medically the same as "squamous cell carcinoma in situ." Squamous cell carcinoma is a tumor that develops from the squamous cells which are flat, scale-like cells in the outer layer of the skin (the epithelium). The term "in situ" (Latin) means "in the natural or normal place" and, in the case of cancer, it says that the tumor cells are still confined to the site where they originated and they have neither invaded neighboring tissues nor metastasized afar. The hallmark of Bowen's disease is a persistent, progressive, slightly raised, red, scaly or crusted plaque. Bowen disease may occur anywhere on the skin surface (or on mucosal surfaces such as in the mouth). Under the microscope, atypical squamous cells are seen to have proliferated through the whole thickness of the epidermis (the outer layer of the skin) but to have gone no farther. The cause of Bowen's disease classically was prolonged exposure to arsenic. Today, Bowen's disease occurs most often in the sun-exposed areas of the skin in older white males.
bp:  In genetics, base pair. In general medicine, blood pressure (but usually in capital letters as BP).
BP:  Commonly used abbreviation for blood pressure. On a medical chart, you might see "BP90/60 T98.6 Ht60/reg R15," which signifies that the blood pressure (BP) is 90/60 mm Hg, the temperature (T) is 98.6° Fahrenheit, the heart rate (Ht) is 60 beats per minute and regular, and respirations are occurring at 15 per minute.
BPH (Benign prostatic hyperplasia):  Nonmalignant enlargement of the prostate gland.
BPPV (benign paroxysmal positional vertigo):  A balance disorder that results in the sudden onset of dizziness, spinning, or vertigo when moving the head.
Brace, Milwaukee:  One of the two main types of braces used to treat the lateral curve of the spine in scoliosis. This brace can be worn to correct any curve in the spine. The brace can be custom made or can be made from a pre-fabricated mold. All braces must be selected for the specific curve problem and fitted to each patient. To have their intended effect (to keep a curve from getting worse), the brace must be worn every day for the full number of hours prescribed by the doctor until the child stops growing. The other type of brace for scoliosis is called a thoracolumbosacral orthosis (TLSO).
Brachial artery:  The artery that runs from the shoulder down to the elbow.
Brachial neuritis:  Inflammation of nerves in the arm causing muscle weakness and pain.
Brachial plexus:  A network of spinal nerves that originates in the back of the neck, extends through the axilla (armpit), and gives rise to nerves to the upper limb. The brachial plexus is formed by the union of portions of the fifth through eighth cervical nerves and the first thoracic nerve, all of which come from the spinal cord.
Brachial vein:  A vein that accompanies the brachial artery between the shoulder and the elbow. The route of the brachial artery is from the shoulder down to the elbow whereas that of the brachial vein is in the reverse direction - from the elbow back up to the shoulder.
Brachycephaly:  A short head, one that is short in diameter from front to back. Brachycephaly is a frequent feature of syndromes of congenital malformation (birth defect complexes) including Down syndrome (trisomy 21).
Brachydactyly:  Short, stubby fingers and toes. Brachydactyly is a frequent feature of syndromes of congenital malformation (constellations of birth defects) including Down syndrome (trisomy 21).
Brachytherapy:  Radiation treatment given by placing radioactive material directly in or near the target, which is often a tumor. Brachytherapy for prostate cancer, for example, is also called interstitial radiation therapy or seed implantation. In brachytherapy for prostate cancer, radioactive seeds are implanted in the prostate. The seeds might be titanium-encased pellets containing the radioisotope iodine-125. "Brachy-" is Greek for "short." The opposite of brachytherapy is teletherapy, treatment in which the radiation source is at a distance from the target.
Brachytherapy of the Coronary Artery:  Local radiation treatment within an artery to the heart. Coronary artery brachytherapy has been used to reduce the recurrence of blockage (obstruction) of a coronary artery after successful treatment of a blockage of a stent. A stent is a tubular structure that is implanted inside of a coronary artery to keep it open, thereby preventing a heart attack. The radiation from coronary artery brachytherapy is believed to prevent cells from reproducing to cause blockage of the blood vessel (coronary artery). Recurrent blockage after placement of a coronary artery stent has been reported to occur in 20 to 30 percent of patients. Stents have never been proven to affect mortality from coronary artery disease and the use of radioactive material in stents strikes this author as piling one mistake on top of another.
Bradycardia:  A slow heart rate, usually defined as less than 60 beats per minute. Athletes typically have bradycardia due to conditioning of the heart allowing the heart to pump adequate blood with less beats. Heart rates of as low as 28 per minute have been recorded. Bradycardia in the absence of athletic conditioning reflects an energy production deficit which can be due to a variety of conditions. The word bradycardia is logically derived from two Greek roots: brady, slow + cardia, heart = slow heart.
Bradykinesia:  Slowed ability to start and continue movements, and impaired ability to adjust the body's position. Can be a symptom of neurological disorders, particularly Parkinson's disease, or a side effect of medications. The word bradykinesia is logically derived from two Greek roots: brady, slow + kinesis, movement = slow movement, slow motion, slow moving.
Bradyphrenia:  Slowed thought processes. Can be a side effect of certain psychiatric medications.
Bradypnea:  (Pronounced brad-ip-nea.) Abnormally slow breathing. A respiratory rate that is too slow. The normal rate of respirations (breaths per minute) depends on a number of factors, including the age of the individual and the degree of exertion. The prefix brady- means slow. The word ending -pnea denotes a relationship to breathing; it comes from the Greek pnoia, meaning breath. The opposite of bradypnea is tachypnea.
Braille system:  A system of raised-dot writing devised by Louis Braille (1809-1852) for the blind in which each letter is represented as a raised pattern that can be read by touching with the fingers.
Brain:  That portion of the central nervous system that is located within the skull. It functions as a primary receiver, organizer and distributor of information for the body. It has two (right and left) halves called "hemispheres." You are using yours now.
Brain biopsy:  Removal of a a small piece of tissue from the brain for diagnostic purposes. One way the procedure may be done is by stereotactic needle biopsy in which the spot to be biopsied is located three-dimensionally, the information is entered into a computer, and the computer calculates the information and positions a needle to remove the biopsy sample. A brain biosy may be done in search for evidence for or against a brain tumor, Alzheimer disease, an inflammatory process in the brain; and so a brain biopsy can be a invaluable source of diagnostic information but it is not without risks. I am not suggesting you have one.
Brain cancer:  Cancer of the central information processing center of the body. Tumors in the brain can be malignant or benign, and can occur at any age. Only malignant tumors are cancerous. In primary brain tumors cancer initially forms in the brain tissue. In secondary brain tumors the cancer has spread (metastasized) to the brain tissue from elsewhere in the body. Secondary brain cancer is named for the organ or tissue in which the cancer begins, such as lung cancer with secondary brain metastasis.
Brain malleability or plasticity:  The phenomenon of how the adult brain changes and learns. It was once thought that specific areas of the brain handled specific tasks and if lost those functions could not be learned again. It is now well appreciated that adjacent parts of the brain can be trained to take over lost functions to some degree.
Brain stem:  The stemlike part of the brain that is connected to the spinal cord. Or conversely, the extension of the spinal cord up into the brain. The brain stem is small but important. It manages messages going between the brain and the rest of the body, and it also controls basic body functions such as breathing, swallowing, heart rate, and blood pressure. The brain stem also controls consciousness and determines whether one is awake or sleepy. The brain stem consists of the midbrain, pons, and medulla oblongata.
Brainstem implant:  A type of hearing aid that bypasses the cochlea in the middle ear and the auditory nerve and is implanted in the brainstem. This type of implant helps individuals who cannot benefit from a cochlear implant because the auditory nerves are not working.
Branchial cleft cyst:  Also called a branchial cyst, this is a cavity that is a remnant from embryologic development present at birth in one side of the neck just in front of the large angulated muscle on either side (the sternocleidomastoid muscle). The cyst may not be recognized until adolescence as it enlarges its oval shape. Sometimes it develops a sinus or drainage pathway to the surface of the skin from which mucus can be expressed. Total surgical excision is the treatment of choice. Recurrence is not expected.
Braxton Hicks contractions:  Irregular contractions of the womb (the uterus) occurring towards the middle of pregnancy in the first pregnancy and, earlier and more intensely, in subsequent pregnancies. These contractions tend to occur during physical activity. The uterus tightens for 30 to 60 seconds beginning at the top of the uterus; and the contraction gradually spreads downward before relaxing. Although said to be painless, Braxton Hicks contractions may be quite uncomfortable and sometimes difficult to distinguish from the contractions of true labor. Named for John Braxton Hicks (1823-1897), a British gynecologist.
BRCA breast cancer gene:  One of several genetic mutations linked to breast cancer and ovarian cancer. There is now convincing evidence that every woman with a BRCA mutation is at high risk for breast cancer, irrespective of whether she has a family history of breast cancer or not. By age 80, a woman with a BRCA mutation has about an 80% chance of developing breast cancer. BRCA1 and BRCA2 increase the risk of ovarian cancer 54% and 23%, respectively. Mutations in BRCA1 or BRCA2 account for 5-10% of all breast cancer which translates into 10,000 to 20,000 new cases of breast cancer in the US and many more around the world every year. The BRCA mutations appear to cause breast cancer at an earlier age in younger generations. The culprit may be estrogen, which is rising with the epidemic of obesity. Pregnancy is protective. BRCA mutation carriers who have children develop breast cancer as a rule later in life than those who never had children. (That finding is true for all types of breast cancer, not just cases caused by BRCA mutations.)
Breakbone fever:  An acute mosquito-borne viral illness of sudden onset that usually follows a benign course with headache, fever, prostration, severe joint and muscle pain, swollen glands (lymphadenopathy) and rash. The presence (the "dengue triad") of fever, rash, and headache (and other pains) is particularly characteristic. Better known as dengue, the disease is endemic throughout the tropics and subtropics. It goes by other names including dandy fever. Victims of dengue often have contortions due to the intense joint and muscle pain. Hence, the name "breakbone fever." Slaves in the West Indies who contracted dengue were said to have "dandy fever" because of their postures and gait.
Breast:  The breast refers to the front of the chest or, more specifically, to the mammary gland. The mammary gland is a milk producing gland. It is composed largely of fat. Within the mammary gland is a complex network of branching ducts. These ducts exit from sac-like structures called lobules, which can produce milk in females. The ducts exit the breast at the nipple.
Breast abscess:  A local accumulation of pus within the breast due to infection. Symptoms may include painful local swelling of the breast, a breast lump, and redness and tenderness of the breast. If the abscess forms in spite of antibiotics, it may need to be incised and drained, a minor surgical procedure, in order to heal.
Breast aplasia:  A rare condition wherein the normal growth of the breast or nipple never takes place. They are congenitally absent. There is no sign whatsoever of the breast tissue, areola or nipple. Absence of the breast (also called, amastia) is frequently not alone as the only problem. Unilateral amastia (amastia just on one side) is often associated with absence of the pectoral muscles (the muscles of the front of the chest). Bilateral amastia (with absence of both breasts) is associated in 40% of cases with multiple congenital anomalies (birth defects) involving other parts of the body as well. Amastia is thought to be described in the Bible: "We have a little sister, and she hath no breasts" (Song of Solomon VIII:8). Amastia can be distinguished from amazia -- wherein breast tissue is absent, but the nipple is present -- a condition that typically is a result of radiation or surgery.
Breast augmentation:  Enlargement of the breasts. Augmentation of the breast typically consists of insertion of a silicone bag (prosthesis) under the breast (submammary) or under the breast and chest muscle (subpectoral) and then filling the bag with saline (salt water). This prosthesis expands the breast area to give a fuller breast (increased cup size), give a better contour, and give more cleavage.
Breast biopsy:  A procedure in which a sample of a suspicious breast growth is removed and examined, usually for the presence of cancer. The sample is suctioned out through a needle or removed surgically. A breast biopsy may be done in a doctor's office, outpatient facility, or hospital operating room. The setting depends on the size and location of the growth, the patient's general health, and the type of biopsy performed.
Breast bone:  Familiar name for the sternum, the long flat bone in the middle of the front of the chest. The sternum consists of three portions: the manubrium (the upper segment of the sternum, a flattened, roughly triangular bone), the corpus or body of the sternum, and the xiphoid process (the little tail of the sternum than points down). These three portions of the sternum arise as separate bones and may fuse partially or completely with one another. The sternum articulates (makes contact) with the cartilages of the first seven ribs and the clavicles (the collar bones) to form the middle portion of the anterior front wall of the thorax.
Breast cancer:  Breast cancer is diagnosed with self- and physician-examination of the breasts, mammography, ultrasound testing, and biopsy. There are many types of breast cancer that differ in their capability of spreading to other body tissues (metastasis). Treatment of breast cancer depends on the type and location of the breast cancer, as well as the age and health of the patient. The American Cancer Society recommends that a woman should have a baseline mammogram between the ages of 35 and 40 years. Between 40 and 50 years of age mammograms are recommended every other year. After age 50 years, yearly mammograms are recommended. The alternative exam is a thermogram which has the advantage of not exposing the subject to x-rays.
Breast cancer metastasis suppressor 1 (BRMS1):   A gene that plays a role in preventing the metastasis (spread) of breast cancer to other parts of the body and so may improve breast cancer survival. The BRMS1 gene is on chromosome 11.
Breast cancer susceptibility genes:  Inherited factors that predispose to breast cancer. Put otherwise, these genes make one more susceptible to the disease and so increase the risk of developing breast cancer. Two of these genes, BRCA1 and BRCA2, have been identified (and prominently publicized). Several other genes are also known to predispose to breast cancer.
Breast cancer, familial:  A number of factors have been identified that increase the risk of breast cancer. One of the strongest of these risk factors is the history of breast cancer in a relative. About15-20% of women with breast cancer have such a family history of the disease, clearly reflecting the participation of inherited (genetic) components in the development of some breast cancers.
Breast cancer, male:  Breast cancer in a man. Male breast cancer is much less common than breast cancer in women. Fewer than 1% of persons with breast cancer are male. However, breast cancer is no less dangerous in males than in females. After the diagnosis of breast cancer is made, the mortality rates are virtually the same for men and for women. Male breast cancer tends to occur after age 50. Men taking estrogen or naturally producing higher levels of the hormone are at increased risk, as are men with Klinefelter syndrome, which results in low testicular function. As with women, men with relatives who carry the breast cancer gene are at elevated risk. And as with breast cancer in women, black men are more likely than white men to die of the disease. About 175,000 women will be diagnosed with breast cancer annually in the US and 40,000 of these women will die of the disease. By comparison, breast cancer will be diagnosed in about 1,500 men this year and 400 of these men will die of their disease.
Breast development, early:  The beginning of breast development at puberty is known medically as thelarche. It is now a normal event at an earlier age (e.g., age 8) than in the past, probably due to hormones used in meat production methods. The term thelarche comes from two Greek words: thele, nipple + arche, beginning.
Breast discharge:  The spontaneous flow of fluid from the nipple at any time other than during nursing. This can be due to an unrecognized pregnancy, trauma, surgery, overexercise, or certain drugs. It can also be due to cirrhosis of the liver, false pregnancy (pseudocyesis), kidney failure, disorders of the spinal cord, or a prolactinoma, a benign pituitary tumor that secretes the hormone prolactin stimulating milk production. Also called galactorrhea.
Breast feeding:  The ability of the breast to produce milk diminishes soon after childbirth without the stimulation of breastfeeding. Immunity factors in breast milk can help the baby to fight off infections. Breast milk contains vitamins, minerals, and enzymes which aid the baby's digestion. Breast feeding is clearly superior to formula feeding and may favorably affect health patterns for a lifetime.
Breast infection:  Infection of breast tissue usually caused by bacteria, most often staph (Staphyloccocus aureus), which are found on the skin and enter the breast through a break in the skin or nipple, as during breast-feeding. The infected breast may be swollen, hot, reddened, and painful. There may be low grade fever. Treatment includes warm wet compresses and antibiotics.
Breast lump:  A localized swelling, knot, bump, bulge or protuberance in the breast. Breast lumps may appear in both sexes at all ages. In women, the fear is usually of breast cancer but many breast lumps turn out, fortunately, to be due to benign conditions that can be successfully treated such as infection, trauma, fibroadenoma, cyst, or fibrocystic condition of the breast. However, no breast lump should be dismissed as benign until it has been checked by a physician.
Breast pain:  Pain in the breast or mammary gland, known medically as mastalgia. From the Greek masto-, breast + algos, pain.
Breast trauma:  Physical damage to a breast. If a breast is injured by trauma, tiny blood vessels may rupture to cause localized bleeding (a hematoma). The hematoma can be felt as a lump. Trauma to the breast can also damage the fat cells in the breast tissue, a condition called fat necrosis. Fat necrosis can form a benign lump in the breast.
Breast, infiltrating ductal carcinoma of the:  Infiltrating ductal carcinoma is one of several recognized specific patterns of cancer of the breast. It is so named because it begins in the cells forming the ducts of the breast. It is the most common form of breast cancer, comprising 65-85% of all cases.
Breast, infiltrating lobular carcinoma of the:   Infiltrating lobular carcinoma is the second most common type of invasive breast cancer next to infiltrating ductal carcinoma, accounting for 5 to 10% of breast cancer. Infiltrating lobular carcinoma starts in the lobules, the glands that secrete milk, and then infiltrates surrounding tissue.
Breast, Paget disease of:  The combination of scaly skin changes of the nipple resembling eczema and an underlying cancer of the breast. The nipple is inflamed because of the presence of Paget's cells. These large irregular cells are themselves not cancerous, but they are almost always associated with a cancer in the breast. The reason for the Paget's cells is still a mystery. In Paget's disease, the nipple and areola (the area surrounding the nipple) are typically red, inflamed and itchy. There may be crusting, bleeding, or ulceration. The nipple may be inverted (turned inwards) and there may be a discharge from the nipple. There is a lump that can be palpated (felt) in the breast in almost half of cases. Paget's disease of the breast accounts for a small but significant minority (1 to 4%) of all breast tumors. It usually occurs in women in their fifties, but it can occur at a later age. Its occurrence in men is a great rarity. It is sometimes called Paget's disease of the nipple.
Breech:  The buttocks.
Breech birth:  Literally, delivery of the baby by the buttocks first, rather than the head as is usual. Breech birth is more likely to cause injury to the mother or the infant. In many cases a baby in the breech position can be "turned" before delivery using repeated, gentle massage of the uterus.
Breslow thickness:  A method for determining the prognosis with melanoma. The thickness of a melanoma is related to the 5-year survival rate after surgical removal of the tumor. Named for the physician Alexander Breslow who in 1975 observed that as the thickness of the tumor increases, the chance of survival goes down. For example, a thickness of the melanoma of less than 0.76 millimeters is associated with a 5-year survival of 97% of patients whereas a tumor thickness of more than 8.0 millimeters is associated with 5-year survival of 32%.
Bridge:  A set of one or more false teeth supported by a metal framework, used to replace one or more missing teeth. Bridges may be fixed or removable. A fixed bridge is a prosthetic replacement of one or more missing teeth; it is cemented (or otherwise attached) to the neighboring teeth or may be implanted in the space. A removable bridge (partial denture) is a prosthetic replacement of one or more missing teeth on a framework that can be removed by the wearer.
Bright's disease:  Chronic inflammation of the blood vessels in the kidney with protein, specifically albumin, in the urine. There are a number of disorders that lead to Bright's disease. With nothing more sophisticated than a candle and a silver spoon, the English physician Richard Bright (1789-1858) discovered protein in urine and in 1827 published his pioneering study of kidney disease.
Brill-Zinsser disease:  Recrudescence of epidemic typhus years after the initial attack. The agent that causes epidemic typhus (Rickettsia prowazekii) remains viable for many years and then when host defenses are down, it is reactivated causing recurrent typhus. The disease is named for the physician Nathan Brill and the great bacteriologist Hans Zinsser.
Brissaud's infantilism:  An eponym that is little used (in the USA) for hypothyroidism (subnormal activity of the thyroid gland) that starts after birth and is manifest by features including delays in growth and development and myxedema surfacing during infancy. Myxedema is a dry waxy type of swelling, often with swollen lips and nose. Infantile hypothyroidism is synonymous with infantile myxedema. Named for the French physician Edouard Brissaud (1852-1909).
BRMs (biological response modifiers):  Substances that stimulate the body's response to infection and disease. The body naturally produces small amounts of these substances. Scientists can produce some of them in the laboratory in large amounts for use in treating cancer, rheumatoid arthritis, and other diseases. BMRs used in biological therapy include monoclonal antibodies interferon, interleukin-2 (IL-2), and several types of colony-stimulating factors (CSF, GM-CSF, G-CSF). Interleukin-2 and interferon are BRMs being tested for the treatment of advanced cases of malignant melanoma. Interferon is a BRM now in use to treat hepatitis C. The side effects of BRM therapy often include flu-like symptoms such as chills, fever, muscle aches, weakness, loss of appetite, nausea, vomiting, and diarrhea. Some patients develop a rash, and some bleed or bruise easily. Interleukin therapy can cause swelling.
Bronchopulmonary:  Pertaining to both the air passages (bronchi) leading to the lungs and the lungs (pulmonae) themselves.
Bronchopulmonary dysplasia:  A chronic lung disease of babies, which most commonly develops in the first 4 weeks after birth and most often affects babies born at least 4 weeks before term. The lungs do not work properly in bronchopulmonary dysplasia (BPD) and the baby has trouble breathing, needs extra oxygen, and may need help from a ventilator (breathing machine). The risk of BPD increases as the baby's weight and time in the mother's uterus decreases. Today, most babies with BPD (9 out of 10) weigh 1,500 grams (about 3 and a half pounds) or less at birth. Babies born weighing less than 1,000 grams (about 2 pounds) are at very high risk. About 1 out 3 of these gets BPD.
Bronchopulmonary segments:  A subdivision of one lobe of a lung based on the connection to the segmental bronchus. For example, the right upper lobe has apical, anterior, and posterior segments.
Bronchoscope:  A thin, flexible instrument used to view the air passages of the lung.
Bronchoscopy:  A procedure that permits the doctor to see the breathing passages through a lighted tube called a bronchoscope.
Bronchospasm, exercise-induced:  Exercise-induced bronchospasm (aks exercise-induced asthma) is triggered by vigorous physical activity. It tends to affect children and young adults because of their high level of physical activity, but can occur at any age. Exercise-induced asthma is initiated by the respiratory heat an cold fluctuations. Rapid rewarming of the bronchi after the cooling effect of rapid breathing, especially in a cold environment, tends to provoke the bronchioles to constrict. Exercise-induced asthma is common. About 85 percent of people who have chronic asthma also have an exercise-induced component and about 40 percent of people with seasonal allergies also have exercise-induced asthma, Symptoms worsen during the spring and fall. Acute attacks can often be avoided by warming up before strenuous activity. Cold dry air is believed to trigger exercise-induced asthma and therefore people prone to this kind of asthma are advised to avoid exercise in a cold dry environment. Indoor swimming may be an ideal form of exercise because the warm, humid air keeps the airways from drying and cooling.

Exercise-induced asthma is monitored using a peak-flow meter, a hand-held device which measures air flow (how fast air is blown out of the lungs). Patients can use peak-flow meters to measure their own air flow regularly. This allows patients to obtain a much earlier indication of an oncoming attack. Exercise-induced asthma can also be managed by avoiding the offending allergic triggers of asthma and by using medications up to an hour before exercise. Bronchodilator meds help relax the muscle spasm of the airways, permitting improved air flow. Other medications can be used to prevent the lining of the airways from swelling in response to cold air or allergic triggers. Inhaled cortisone related medications can be used to reduce inflammation and swelling in the airways. While in the past athletes were forced out of competition because of exercise-induced asthma, today the condition is manageable in most cases. Exercise-induced asthma is also known as exercise-induced asthma and also as thermally induced asthma.

Bronchus:  One of the large air tubes leading from the trachea to the lungs that convey air to and from the lungs. The bronchi (plural) have cartilage as part of their supporting wall structure. The trachea divides to form the right and left main bronchi which, in turn, divide to form the lobar, segmental, and finally the subsegmental bronchi.
Brontophobia:  An abnormal and persistent fear of thunder that causes undue anxiety even though sufferers realize that thunder itself poses no threat to them. When outdoors during a thunderstorm, they may suffer excessive anxiety. When indoors, they may hide under beds or desks, behind sofas, or in closets. "Brontophobia" is derived from the Greek "bronte" (thunder) and "phobos" (fear). This same Greek word has given us the English word "brontometer," an instrument for recording the activity of thunderstorms; also "Brontosaurus" (thunder lizard).
Brown fat:  Brown adipose tissue, a rapid source of energy for infants in whom it forms about 5% of their body weight. It is brown because the cells in it are packed full of small cellular organs called mitochondria, which are energy factories, and it has a rich supply of blood vessels. Brown fat is virtually gone by adulthood.
Brown syndrome:  An abnormality present at birth characterized by an inability to elevate the eyeball when trying to look to the side. These people can look to the left or right, but not up to the left or up to the right.
Brown, Louise:  The world's first test-tube baby, conceived by in vitro fertilization and born on July 25, 1978.
Bruce protocol:  A standardized multistage treadmill test for assessing cardiovascular health, The test was developed and described in 1963 by the American cardiologist Robert A. Bruce (1916-2004). According to the original Bruce protocol, the patient walks on an uphill treadmill in a graded exercise test with electrodes on the chest to monitor the EKG. Every 3 minutes, the speed and incline of the treadmill are increased. There are 7 such stages and only very fit athletes can complete all 7 stages. The modified Bruce protocol is an alteration in the protocol so that the treadmill is initially horizontal rather than uphill, with the first few intervals increasing the treadmill slope only. The test can detect evidence of angina pectoris (chest pain and discomfort), a previous heart attack, and ventricular aneurysm (bulging in the ventricle of the heart).
Brucellosis:  An infectious disease due to the various species of the bacteria genus Brucella that causes rising and falling fevers, sweats, malaise, weakness, anorexia, headache, myalgia (muscle pain) and back pain. It also called undulant fever because the fever is typically undulant, rising and falling like a wave. Brucellosis is transmitted through contaminated and untreated milk and milk products and by direct contact with infected animals (cattle, sheep, goats, pigs, camels, buffaloes, wild ruminants and, very recently, seals), and animal carcasses.
Bruise:  A bruise or "contusion" is an traumatic injury of the soft tissues which results in breakage of the local capillaries and leakage of red blood cells. In the skin it can be seen as a reddish-purple discoloration that does not blanch when pressed upon. When a bruise fades it becomes green and brown as the body metabolizes the hemoglobin of the blood cells. It is best treated with local application of a cold pack immediately after injury.
Brushfield's spots:  Speckled iris. Little white spots that slightly elevated on the surface of the iris arranged in a ring concentric with the pupil. These spots occur in normal children but are far more frequent in Down's syndrome (Trisomy 21). They were described in 1924 by Thomas Brushfield and are due to aggregation of a normal iris element (connective tissue).
Bruxism:  Grinding and gnashing the teeth. Bruxism is due to clenching of the teeth other than in chewing and is associated with forceful lateral or protrusive jaw movements. This results in grinding or rubbing the teeth together. Bruxism usually occurs during sleep. It is sometimes done to such an excess that it damages the occlusal surfaces of the teeth, particularly the molar teeth, and may contribute to the temporomandibular joint (TMJ) syndrome.
Bubble Boy Disease (aka Severe combined immunodeficiency disease):  A combined deficiency of the immune system's two major weapons -- antibodies and T cells -- are genetically missing or disabled. Severe combined immunodeficiency disease (SCID) is rare. The chances of a child being born with SCID are about one in 500,000 births. Until recent years, it was always fatal. There are a number of different causes of SCID. Each is caused by a different genetic defect, and each develops along a different pathway:
Bubo:  An enlarged lymph node ("swollen gland") that is tender and painful, particularly in the groin and armpit (the axilla). A feature of a number of infectious diseases including gonorrhea, syphilis, tuberculosis, and the plague. Hence, the bubonic plague. The odd word "bubo" comes from the Greek boubon meaning groin or swollen groin.
Bubonic plague:  The most common form of the plague, named for the characteristic buboes - buboes are enlarged lymph nodes ("swollen glands") - in the groin which are usually very tender and painful. Lymph nodes may be similarly affected elsewhere such as in the armpits and neck. Common but less specific features of the disease include headache, fever, chills, and weakness. The bubonic plague is caused by bacteria called Yersinia pestis. The bacteria are transmitted from infected rats to the oriental rat flea to people. The rats are a "reservoir" for the disease. The fleas are the "vectors" that carry the bacteria from the rat reservoir to the human host. The bubonic plague caused the "black death" (the black plague) characterized by gangrene of the fingers, toes, and nose.
Buccal mucosa:  The inner lining of the cheeks and lips.
Bulbar:  Pertaining to a bulb, in medicine any rounded mass of tissue (that is shaped somewhat like a crocus or tulip bulb).
Bulbar conjunctiva:  That part of the conjunctiva, the clear membrane covering of the eye, which covers the outer surface of the eye. The other part of the conjunctiva is the palpebral conjunctiva, which lines the inside of the eyelids. The bulbar conjunctiva is also called the ocular conjunctiva.
Bulbourethral gland:  Also called Cowper's gland. A pea-sized gland in the male located behind and to the side of the urethra that discharges a component of seminal fluid into the urethra. There are two bulbourethral glands, one on each side. They are the counterparts of Bartholin's glands in the female.
Bulimia:  Also called bulimia nervosa. An eating disorder characterized by episodes of secretive excessive eating (binge-eating) followed by inappropriate methods of weight control, such as self-induced vomiting (purging), abuse of laxatives and diuretics, or excessive exercise. The insatiable appetite of bulimia is often interrupted by periods of anorexia (abstinence from eating). Like anorexia, bulimia is generally thought to be a psychological eating disorder. The cycle of overeating and purging can quickly become an obsession similar to an addiction to drugs or other substances. Although bulimia has been widely considered to be psychological and sociocultural in origin, not everyone is susceptible to developing bulimia. There is now a substantial literature showing that bulimia is strongly familial and that the pronounced familial nature of bulimia is due largely to the additive effects of a number of genes. One bulimia susceptibility gene is known to be linked to chromosome 10p (the short arm of chromosome 10).
Bulla:  A fluid-filled blister more than 5 mm (about 3/16 inch) in diameter with thin walls. A bulla on the skin is a blister. A bulla on the pleura (the membrane covering the lung) is also called a bleb. The plural is bullae.
Bullous:  Characterized by blistering, such as in a second-degree burn. Bullous is the adjective for bulla.
Bullous pemphigoid:  A disease characterized by tense blistering eruptions of the skin. caused by antibodies abnormally accumulating in a layer of the skin called the "basement membrane." Can be chronic and mild without affecting the general health. It is diagnosed by skin biopsy showing the abnormal antibodies deposited in the skin layer. Treatment is with topical cortisone creams, but sometimes requires high doses of cortisone ("steroids") taken internally, although these have severe side-effects which discourage their use.
BUN (blood urea nitrogen):  A measure of the urea level in blood. Urea is cleared by the kidneys and diseases which compromise the function of the kidneys will frequently lead to increased blood levels. The blood BUN level can also rise in patients who are dehydrated and in people who have recently engaged in heavy exercise.
Bunion:  A localized painful swelling at the base of the big toe (the great toe). The joint is enlarged (due to new bone formation) and the toe is often misaligned. It is frequently associated with inflammation. It can be related to inflammation of the nearby bursa (bursitis) or degenerative joint disease (osteoarthritis). Bunions most commonly affect women. Ballet dancers are prime candidates for bunions. Tight-fitting shoes and high heels can contribute to bunions. The treatment of bunions includes rest, a change in shoes, foot supports, medications or surgery.
Burkitt lymphoma:  A type of non-Hodgkin lymphoma (NHL) that most often occurs in young people between the ages of 12 and 30, accounting for 40% to 50% of childhood NHL. The disease usually causes a rapidly growing tumor in the abdomen. Up to 90% of these tumors are in the abdomen. Other sites of involvement include the testis, sinuses, bone, lymph nodes, skin, bone marrow, and central nervous system. Burkitt lymphoma is a small noncleaved cell lymphoma of B-cell origin. About 25% of Burkitt lymphomas contain Epstein-Barr virus genomes. Burkitt lymphoma is due to a characteristic chromosomal translocation.
Burning mouth syndrome:  An intense burning sensation on the tongue, often at the tip of the tongue. The burning mouth syndrome tends to develop in supertasters and post-menopausal women. Supertasters have an unusually large density of taste buds, each surrounded by pain fibers. Post-menopausal women with the burning mouth syndrome often lose their ability to sense bitter tastes. Clonazepam, an anti-seizure drug, is reportedly effective in treating burning mouth syndrome in more than 70% of patients.
Burning on Urination (also called Dysuria):   Painful or difficult urination. Dysuria is most commonly due to bacterial infection of the urinary tract causing inflammation of the bladder (cystitis) or kidney (pyelonephritis). In women, dysuria may also reflect inflammation of the vagina (vaginitis) or vulva (vulvitis). And in men, dysuria may be due to inflammation of the prostate (prostatitis) or the urethra (urethritis) from gonorrhea or chlamydia. There are many other causes of dysuria including irritation from chemicals in soaps, bubble baths, spermicides, and douches.
Burns, first degree:  A first degree burn is superficial and has similar characteristics to a typical sun burn. The skin is red in color and sensation is intact. In fact, it is usually somewhat painful.
Burns, second degree:  Second degree burns look similar to the first degree burns in that it is red and sensation is intact; however, the damage is severe enough to cause blistering of the skin and the pain is usually somewhat more intense.
Burns, third degree:  In third degree burns the damage has progressed to the point of skin death. The skin is white and without sensation.
Bursa:  A closed fluid-filled sac that functions to provide a gliding surface to reduce friction between tissues of the body. When the bursa becomes inflamed, the condition is known as bursitis. Bursa is the Greek word for "a wine skin." Plural is bursae. If the cause is infection, it is called septic bursitis. Absent the infection and it is called aseptic bursitis. Chronic (repeated of long-standing) inflammation of the bursa (bursitis) can lead to calcification of the bursa. This is referred to as calcific bursitis. The calcium deposition (calcification) can occur as long as the inflammation is present.
Buruli ulcer:  A disorder caused by infection with a member of the family of bacteria that causes tuberculosis and leprosy - the bacterium Mycobacterium ulcerans - that starts as a painless swelling in the skin, most commonly in the limbs (the arms and legs) and causes severely deforming ulcers. Complications include loss of organs such as the eye and breast, amputation of limbs and other permanent disabilities.
Butterfly rash:  A red, flat facial rash over the bridge of the nose. Over half of patients with systemic lupus erythematosus (SLE) develop this characteristic rash. Because of its shape, it is frequently referred to as the "butterfly rash" of lupus.
Butyric acid:  An acid that has four carbons in it. The formula for butyric acid is: CH3-CH2-CH2-COOH. The salt form is called butyrate and is used orally to prevent colon cancer. It is a ready source of energy for metabolism in the colon.
Bypass:  An operation in which a surgeon creates a new tubular pathway for the movement of fluids and/or other substances in the body around a blocked passageway.



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