Lupus Erythematosus

Lupus Erythematosus, chronic autoimmune disease in which the immune system treats the body’s own tissue as a foreign substance and produces antibodies to fight it. The damage caused by these antibodies may produce symptoms such as a characteristic butterfly-shaped rash on the face, headache, fatigue, arthritic joint disease, heart damage, shortness of breath, and impaired kidney function. Commonly known as lupus, the disease follows an irregular course of remissions and flare-ups, and may often be incapacitating

Diagnosis of lupus is difficult and can take years because symptoms are intermittent or may mimic other disorders. Diagnosis begins with a complete medical history, a physical examination, blood tests, and other studies that may be necessitated by the patient’s symptoms. The physician, normally a rheumatologist (an expert on musculoskeletal and immune system conditions) must consider and rule out other disorders such as chronic fatigue syndrome or mononucleosis before confirming the diagnosis.

Treatment for lupus requires a balance of medication and the control of environmental factors. Medications include aspirin and other nonsteroidal anti-inflammatory drugs as well as prescription drugs such as antimalarials, which relieve joint, skin, and fatigue symptoms, and corticosteroids, strong substances that suppress the immune response. A patient with lupus should avoid sunlight, eat a healthy diet, exercise, and minimize stress.

Transient Ischemic Attack

Transient Ischemic Attack (TIA), medical term for a ministroke, a sudden loss of function in one region of the brain. Symptoms may include double vision or temporary loss of vision, speech difficulties, vomiting, loss of sensation and movement on one side of the body, dizziness, unsteadiness, and loss of memory. Loss of consciousness is rare. Symptoms usually reach a peak within seconds and last for minutes or hours. Recovery is complete, but TIAs tend to recur.

A TIA is caused by the obstruction of small blood vessels by tiny blood clots or, less often, by reduced blood supply to the brain associated with diseases of the heart or blood vessels, such as narrowing of the arteries due to atherosclerosis. Aspirin, because of its anticlotting properties, may reduce the risk of TIAs in some patients. Other cases may be helped by an operation known as carotid artery endarterectomy, used to clear blockage of the carotid artery in the neck.

Yellow Fever

Yellow Fever, noncontagious, infectious disease, caused by a virus, and characterized in severe cases by high fever and jaundice. Originally yellow fever was believed to be exclusively a disease of humans, but research has revealed that it also affects monkeys and other animals. It is believed that diseased monkeys of Africa and tropical America are the primary source of infection and that carrier mosquitoes transmit the infection to humans. This type of the disease, which occurs only sporadically in human beings, is known as jungle yellow fever. If infected individuals move into a populated area, they may be bitten by a semidomestic species of mosquito, such as Aëdes aegypti, which lives close to human habitations. These feed on the blood of humans and are the chief transmitting agents in epidemics of urban yellow fever.

Whooping Cough

Whooping Cough, also known as pertussis, common name applied to an acute, infectious disease of the respiratory tract, caused by the bacillus Bordetella pertussis. The disease is characterized in its late stages by a deep cough ending in a peculiar high-pitched whooping sound. Whooping cough occurs worldwide, periodically in epidemics.

Infection with pertussis usually occurs by inhaling droplets sprayed into the air during coughing or sneezing spells by an infected person. Once inside the respiratory tract, pertussis bacteria produce toxins (poisonous chemicals) that interfere with the respiratory tract’s ability to eliminate microbial infections. Pertussis bacteria also produce chemicals that cause inflammation of the lining of the respiratory tract.

The disease begins with a runny nose, a harsh cough, and a slight fever. The characteristic whoop develops one to two weeks later. Coughing spells, which usually occur at night and often end in vomiting, can continue to occur for four weeks or more. Complications of pertussis may include pneumonia and seizures.

Physicians treat whooping cough with antibiotics. Other treatments include controlling coughing with sedatives and replacing fluids lost by vomiting. Use of pertussis vaccine during the first year of life provides immunity to the infection in most children. Pertussis vaccine is usually given together with diphtheria and tetanus vaccines in a shot called DTaP.

Vitamin K

This vitamin is necessary mainly for the coagulation of blood. It aids in forming prothrombin, an enzyme needed to produce fibrin for blood clotting. The richest sources of vitamin K are alfalfa and fish livers, which are used in making concentrated preparations of this vitamin. Dietary sources include all leafy green vegetables, egg yolks, soybean oil, and liver. For a healthy adult, a normal diet and bacterial synthesis in the bowels usually are sufficient to supply the body with vitamin K and prothrombin. Digestive disturbances may lead to defective absorption of vitamin K and hence to mild disorders in blood clotting.

Vitamin E

The role of vitamin E in the human body is known to be an essential nutrient in more than 20 vertebrate species. The vitamin plays some role in forming red blood cells and muscle and other tissues and in preventing the oxidation of vitamin A and fats. It is found in vegetable oils, wheat germ, liver, and leafy green vegetables. Vitamin E is popularly advocated for a wide range of diseases, but no substantial evidence has been found to back these claims. Although vitamin E is stored in the body, overdoses appear to have lower toxic effects than do overdoses of other fat-soluble vitamins.

Vitamin D

This vitamin is necessary for normal bone formation and for retention of calcium and phosphorus in the body. It also protects the teeth and bones against the effects of low calcium intake by making more effective use of calcium and phosphorus. Also called the sunshine vitamin, vitamin D is obtained from egg yolk, liver, tuna, and vitamin-D fortified milk. It is also manufactured in the body when sterols, which are commonly found in many foods, migrate to the skin and become irradiated. Vitamin D deficiency, or rickets, occurs only rarely in tropical climates where sunlight is abundant, but it was once common among children of other areas before the use of vitamin D-fortified milk. Rickets is characterized by deformities of the rib cage and skull and by bowlegs, due to failure of the body to absorb calcium and phosphorus. Because vitamin D is fat-soluble and stored in the body, excessive consumption can cause vitamin poisoning, kidney damage, lethargy, and loss of appetite.

Vitamin C

Vitamin C or ascorbic acid, a well-known vitamin is important in the formation and maintenance of collagen, the protein that supports many body structures and plays a major role in the formation of bones and teeth. It also enhances the absorption of iron from foods of vegetable origin. Scurvy is the classic manifestation of severe ascorbic acid deficiency. Its symptoms are due to loss of the cementing action of collagen and include hemorrhages, loosening of teeth, and cellular changes in the long bones of children. Assertions that massive doses of ascorbic acid prevent colds and influenza have not been borne out by carefully controlled experiments. In other experiments, however, ascorbic acid has been shown to prevent the formation of nitrosamines—compounds found to produce tumors in laboratory animals and possibly also in humans. Although unused ascorbic acid is quickly excreted in the urine, large and prolonged doses can result in the formation of bladder and kidney stones, interference with the effects of blood-thinning drugs, destruction of B12, and the loss of calcium from bones. Sources of vitamin C include citrus fruits, fresh strawberries, cantaloupe, pineapple, and guava. Good vegetable sources are broccoli, brussels sprouts, tomatoes, spinach, kale, green peppers, cabbage, and turnips.

The B Vitamins

Known also as vitamin B complex, these are fragile, water-soluble substances, several of which are particularly important to carbohydrate metabolism.

Vitamin B1
Thiamine, or vitamin B1, a colorless, crystalline substance, acts as a catalyst in carbohydrate metabolism, enabling pyruvic acid to be absorbed and carbohydrates to release their energy. Thiamine also plays a role in the synthesis of nerve-regulating substances. Deficiency in thiamine causes beriberi, which is characterized by muscular weakness, swelling of the heart, and leg cramps and may, in severe cases, lead to heart failure and death. Foods richest in thiamine are pork, organ meats (liver, heart, and kidney), brewer's yeast, lean meats, eggs, leafy green vegetables, whole or enriched cereals, wheat germ, berries, nuts, and legumes. Milling of cereal removes those portions of the grain richest in thiamine; consequently, white flour and polished white rice may be lacking in the vitamin. Widespread enrichment of flour and cereal products has largely eliminated the risk of thiamine deficiency, although it still occurs today in nutritionally deficient alcoholics.

Vitamin B2
Riboflavin, or vitamin B2, like thiamine, serves as a coenzyme—one that must combine with a portion of another enzyme to be effective—in the metabolism of carbohydrates, fats, and, especially, respiratory proteins. It also serves in the maintenance of mucous membranes. Riboflavin deficiency may be complicated by a deficiency of other B vitamins; its symptoms, which are not as definite as those of a lack of thiamine, are skin lesions, especially around the nose and lips, and sensitivity to light. The best sources of riboflavin are liver, milk, meat, dark green vegetables, whole grain and enriched cereals, pasta, bread, and mushrooms.

Vitamin B3
Niacin, also known as nicotinic acid and vitamin B3, also works as a coenzyme in the release of energy from nutrients. A deficiency of niacin causes pellagra, the first symptom of which is a sunburnlike eruption that breaks out where the skin is exposed to sunlight. Later symptoms are a red and swollen tongue, diarrhea, mental confusion, irritability, and, when the central nervous system is affected, depression and mental disturbances. The best sources of niacin are liver, poultry, meat, canned tuna and salmon, whole grain and enriched cereals, dried beans and peas, and nuts. The body also makes niacin from the amino acid tryptophan. In large amounts it reduces levels of cholesterol in the blood, and it has been used extensively in preventing and treating arteriosclerosis. Large doses over long periods cause liver damage.

Vitamin B6
Pyridoxine, or vitamin B6, is necessary for the absorption and metabolism of amino acids. It also plays roles in the use of fats in the body and in the formation of red blood cells. Pyridoxine deficiency is characterized by skin disorders, cracks at the mouth corners, smooth tongue, convulsions, dizziness, nausea, anemia, and kidney stones. The best sources of pyridoxine are whole (but not enriched) grains, cereals, bread, liver, avocadoes, spinach, green beans, and bananas. Pyridoxine is needed in proportion to the amount of protein consumed.

Vitamin B12
Cobalamin, or vitamin B12, one of the most recently isolated vitamins, is necessary in minute amounts for the formation of nucleoproteins, proteins, and red blood cells, and for the functioning of the nervous system. Cobalamin deficiency is often due to the inability of the stomach to produce glycoprotein, which aids in the absorption of this vitamin. Pernicious anemia results, with its characteristic symptoms of ineffective production of red blood cells, faulty myelin (nerve sheath) synthesis, and loss of epithelium (membrane lining) of the intestinal tract. Cobalamin is obtained only from animal sources—liver, kidneys, meat, fish, eggs, and milk. Vegetarians are advised to take vitamin B12 supplements.

Other B Vitamins
Folic acid, or folacin, is a coenzyme needed for forming body protein and hemoglobin. Recent investigations show that folic acid deficiency may be responsible for neural tube defects, a type of birth defect that results in severe brain or neurological disorders. Folic acid is effective in the treatment of certain anemias and sprue. Dietary sources are organ meats, leafy green vegetables, legumes, nuts, whole grains, and brewer's yeast. Folic acid is lost in foods stored at room temperature and during cooking. Unlike other water-soluble vitamins, folic acid is stored in the liver and need not be consumed daily.

Pantothenic acid, another B vitamin, plays a still-undefined role in the metabolism of proteins, carbohydrates, and fats. It is abundant in many foods and is manufactured by intestinal bacteria as well.

Biotin, a B vitamin that is also synthesized by intestinal bacteria and widespread in foods, plays a role in the formation of fatty acids and the release of energy from carbohydrates. Its deficiency in humans is unknown.

Vitamin A

Vitamin A is a pale yellow primary alcohol derived from carotene. It affects the formation and maintenance of skin, mucous membranes, bones, and teeth; vision; and reproduction. An early deficiency symptom is night blindness (difficulty in adapting to darkness); other symptoms are excessive skin dryness; lack of mucous membrane secretion, causing susceptibility to bacterial invasion; and dryness of the eyes due to a malfunctioning of the tear glands,

The body obtains vitamin A in two ways. One is by manufacturing it from carotene, a vitamin precursor found in such vegetables as carrots, broccoli, squash, spinach, kale, and sweet potatoes. The other is by absorbing ready-made vitamin A from plant-eating organisms. In animal form, vitamin A is found in milk, butter, cheese, egg yolk, liver, and fish-liver oil. Excess vitamin A can interfere with growth, stop menstruation, damage red blood corpuscles, and cause skin rashes, headaches, nausea, and jaundice.

Undulant Fever

Undulant Fever, also known as brucellosis, infectious disease caused by various species of bacteria of the genus Brucella, transmitted to humans from lower animals, especially cattle, hogs, and goats. Human beings acquire the disease through contact with infected animals or by drinking their raw milk. The disease has been known as Malta fever, Bang's disease, Mediterranean fever, rock fever, and goat fever. In animals the disease generally can cause partial sterility, decreased milk supply, and abortion of a fetus. In humans undulant fever assumes acute and chronic forms. The acute form is characterized by weakness, chills, and high night fevers and often results in central nervous system disorders, painful joints, and miscarriage.

Chronic undulant fever is difficult to diagnose, as the symptoms are exceedingly varied and vague. A diagnostic blood agglutination test is available. As a rule human beings suffering from undulant fever respond favorably to the administration of broad-spectrum antibiotics. The pasteurization of milk is essential to the control of undulant fever.

Ulcerative Colitis

Ulcerative Colitis, a chronic disease of unknown cause in which the lining of the colon and rectum becomes severely inflamed and eventually wears away, forming shallow sores known as ulcers. Frequently the colon is permanently damaged. Ulcerative colitis, together with a related condition called Crohn’s disease, are generally referred to as inflammatory bowel diseases (IBDs).

Most people with ulcerative colitis have inflammation in their descending colon, the section of the large intestine stretching from the left side of the abdomen to the pelvis, and in the sigmoid colon, the section of the intestine that is joined to the rectum. Some people have inflammation and ulceration in all of the large intestine. The disease does not affect the small intestine.

Most people have only mild or moderate forms of the disease, with symptoms that include rectal bleeding, diarrhea, and feces that contains mucus, all of which are easily controlled with medication. People with a more severe form of the disease have extensive diarrhea, stomach pain, and fever, and they also tend to suffer from such problems as arthritis, liver problems, and leg ulcers. Patients with ulcerative colitis involving the whole colon that has lasted for more than ten years are at major risk for cancer.

Tumor

Tumor, broadly interpreted, any abnormal local increase in size of a tissue or organ. Medical research at the microscopic level, however, has made clear that swelling can be due either to the infiltration of cells from another part of the body or to the proliferation of cells originating within the affected site itself; only the latter circumstance is called a tumor.

Tumors are classified as either benign or malignant, although the benign-malignant distinction is not universally useful. The most important property rendering a tumor malignant is the ability to invade nearby or distant tissues; this spread to distant tissues is called metastasis, and it usually occurs by means of the blood or lymph vessels. Some so-called benign tumors can kill without metastasizing. Chief among these are brain tumors called gliomas, which can grow large enough to exert substantial pressure on nearby brain structures and destroy respiratory function. A liver tumor can kill by destroying the vital functions of that organ, even without metastasis. Cells in malignant tumors are also sometimes said to have lost their characteristic function, but blood cells form tumors, called myelomas, in which the cells retain the ability to form antibodies. Tumors of the uterus, called hydatidiform moles, are benign, but they can be forerunners of the cancer called choriocarcinoma. The clearest cases of benign tumors are skin moles and warts.

Trypanosomiasis

Trypanosomiasis, also sleeping sickness, endemic, and sometimes epidemic, chronic disease caused by a protozoan blood parasite, genus Trypanosoma. In cattle and other animals, which serve as the reservoir for the protozoa, the disease is called nagana. Two variations of the disease occur in central and western Africa, both of them transmitted in the salivary glands of infected tsetse flies. The most common is caused by T. brucei gambiense, whereas a more local version is caused by T. brucei rhodesiense.

African sleeping sickness begins with a chancre at the site of the insect bite, an accelerated heartbeat, an enlargement of the spleen, and rash and fever. Over the next few months the nervous system is attacked, with accompanying mood changes, sleepiness, lack of appetite, eventual coma, and, frequently, death. Chagas' disease, which more frequently attacks children, also involves fever and damage to the spleen and nervous system, as well as to the liver and the heart muscles. It is also sometimes fatal. In early stages, African sleeping sickness can be alleviated by the administration of various antiparasitic drugs; treatment in later stages with arsenic-containing drugs is less likely to be effective.

Encephalitis is also sometimes called sleeping sickness.

Trench Mouth

Trench Mouth, acute infectious disorder of the mucous membranes of the mouth and throat, so called from its prevalence among World War I soldiers. It is characterized by painful ulcerations. Predisposing factors for infection include poor oral hygiene. The main causative organisms are the bacillus Fusiformis dentium and the spirillum Borrelia vincenti. Painful and bleeding gums are the chief symptoms, and they are usually accompanied by malodorous breath and an unpleasant taste in the mouth. Treatment consists of relieving the painful symptoms of the acute bacterial state and correcting local and systemic predisposing causes of the disease. Antibiotics are usually effective in controlling the infection.

Toxic Shock Syndrome

Toxic Shock Syndrome (TSS), rare disease associated with strains of the bacterium Staphylococcus aureus, a common inhabitant of the skin, oral cavity, and vagina. Under certain conditions the bacterium produces a toxin that apparently attacks the immune system through the bloodstream, in turn permitting more toxin to be produced. Liver function is also altered, resulting in liver and kidney damage. Symptoms of TSS include rash, high fever, lowered blood pressure, diarrhea, and vomiting. TSS has caused death in about 3 percent of reported cases. The disease can be treated with antibiotics.

Toxemia

Toxemia, poisoned condition of the blood caused by the presence of toxic materials, usually bacterial but occasionally chemical or hormonal in nature. When bacteria themselves find entrance into the bloodstream, the condition is known as bacteremia. Toxins are not due to absorption of putrefied or fermented foodstuffs, nor are they absorbed from the colon in conditions of constipation.

The term toxemia is also sometimes applied to preeclampsia, a condition that occasionally occurs in late pregnancy and is characterized by high blood pressure and kidney malfunction.

Thrush

Thrush (medicine), fungal infection characterized by creamy-white, curdlike patches on the tongue and other mucosal surfaces of the mouth. The disease is caused by an overgrowth of Candida albicans, a species of yeast that normally inhabits the mucous membranes as a benign saprophyte. Those most susceptible to thrush include adults whose immune systems have been weakened by antibiotics, steroids, or, most commonly, acquired immunodeficiency syndrome (AIDS). Infants can become infected during birth if the mother has a vaginal yeast infection.

When the curdlike discharge is removed from patches of thrush, raw and bleeding areas are visible and can be especially painful. If left untreated, these superficial lesions may allow the yeast to spread to other areas of the body. In cases of severe immunosuppression or prolonged antibiotic therapy, the organism can invade the major organs, causing serious complications. Diagnosis requires microscopic identification of the pseudomycelial (branching-arms) forms. Generally, thrush is treated with a topical agent such as miconazole or clotrimazole.

Thiamine

Thiamine, also called vitamin B1, a substance that enables carbohydrates in the body to release the energy required for cellular function, known as metabolism. Thiamine also plays a vital role in the activities of enzymes, proteins that are involved in bodily processes such as digestion. Good sources of thiamine include wheat germ, dry beans, peas, enriched cereals and breads, pasta, nuts, eggs, and most vegetables. Lean pork is one of the best sources of the vitamin, as are organ meats, such as liver.

Thiamine deficiency is a risk for the elderly, for people of all ages who participate in strenuous exercise, and for those who are severely ill. A severe lack of thiamine causes the vitamin-deficiency disease known as beriberi, a neurological and cardiovascular disorder characterized by muscular weakness, swelling of the heart, leg cramps, and, in severe cases, heart failure and death. Thiamine deficiency in severe alcoholics (a result of malnutrition) may lead to a central nervous system condition known as Wernicke-Korsakoff syndrome, which can cause paralysis of the eye muscles, extreme memory loss, and dementia.

Tetanus

Tetanus, serious infectious disease of the nervous system, in which a bacterial toxin causes severe muscle spasm. Also called lockjaw, the bacterial infection occurs when wounds are contaminated with a bacillus, Clostridium tetani, which is found everywhere but which is especially likely to be present in street dirt. It is an anaerobic bacillus—that is, one that lives without oxygen, and thus when introduced into human tissue, usually at the time of an injury, it can multiply where the oxygen is deficient. This occurs both in deep, penetrating wounds and in crushing wounds with extensive tissue destruction. As the bacillus multiplies, large amounts of exotoxin are released into the surrounding tissues.

The incubation period varies from two weeks to several months, but generally is about two weeks. The first symptoms are usually headache and depression, followed by difficulty in swallowing and in opening the jaws. Stiffness of the neck develops and gradually a spasm of the cheek muscles sets the face in a peculiar, sardonic grin. Eventually, the spasms spread to other muscles of the body.

Treatment, besides cleaning the wound, involves eliminating the bacilli both surgically and with antibiotics, neutralizing the exotoxin with antitoxin, reducing muscle spasm, and supporting or aiding respiration. A series of three injections is recommended if the tetanus toxoid is combined with both diphtheria and toxoid pertussis (whooping cough) vaccine in the commonly administered DTP (diphtheria, tetanus, pertussis) injections. The supplementary booster injections should be given one year after completion of the primary immunization series and every five to ten years thereafter.

Syphilis

Syphilis, infectious disease caused by the spirochete Treponema pallidum and usually transmitted by sexual contact or kissing. Infection from contaminated objects is infrequent, because drying quickly kills the organisms. A fetus carried by a woman with syphilis may contract the disease, a condition called congenital syphilis.

Syphilis is detected by symptoms and verified by one of several tests performed on the blood or spinal fluid, the most common of which is the VDRL (venereal disease research laboratory) test. The preferred drug for treatment is benzathine penicillin, which is given in two injections one week apart for all stages but neurosyphilis. For this advanced stage, the antibiotic is given three times at weekly intervals. Syphilis control includes tracking down all sexual contacts of infected persons and treating those who had contact during the infectious period. Use of condoms offers some protection against contracting syphilis.

Streptococcus

Streptococcus, genus of spherical, gram-positive, aerobic bacteria. The streptococci occur in pairs or chains, and some species are pathogenic in humans. Streptococcal infections include strep throat, scarlet fever, erysipelas, puerperal fever, and some pneumonias. The drugs of choice for treating such infections are penicillin and erythromycin. Cultures of nonpathogenic lactic streptococci are used in the fermentation of dairy products such as cheese and buttermilk.

Smallpox

Smallpox, highly contagious viral disease that is often fatal. The disease is chiefly characterized by a skin rash that develops on the face, chest, back, and limbs. Over the course of a week the rash develops into pustular (pus-filled) pimples resembling boils. In extreme cases the pustular pimples run together—usually an indication of a fatal infection. Death may result from a secondary bacterial infection of the pustules, from cell damage caused by the viral infection, or from heart attack or shock. In the latter stages of nonfatal cases, smallpox pustules become crusted, often leaving the survivor with permanent, pitted scars.

Smallpox is caused by a virus. An infected person spreads virus particles into the air in the form of tiny droplets emitted from the mouth by speaking, coughing, or simply breathing. The virus can then infect anyone who inhales the droplets. By this means, smallpox can spread extremely rapidly from person to person.

Sickle-Cell Anemia

Sickle-Cell Anemia, genetic disorder of the blood leading to frequent and severe infections, damage to major organs, and episodes of unpredictable pain in the back, chest, abdomen, and extremities. Early symptoms appear at about six months of age and may include serious infections, pain and swelling in the hands and feet, and enlargement of the abdomen and heart.

Sickle-cell anemia is caused by a defective gene that produces an abnormal form of hemoglobin, the component of red blood cells responsible for transporting oxygen from the lungs to the tissues. The abnormal hemoglobin, called hemoglobin S, distorts red blood cells after they release oxygen in the tissues. These distorted cells are called sickled cells because of their resemblance to the sickle, a type of crescent-shaped cutting blade used in agriculture. The sickled shape makes it difficult for these cells to pass through tiny blood vessels, resulting in intensely painful blockages that prevent vital oxygen and nutrients in the blood from reaching organs and tissues, impairing their function. As a result, sickle-cell patients are also vulnerable to a number of infections. When the blood flow to the brain is affected, sickle-cell patients may experience brain damage, such as stroke. Sickle cells also break apart more readily than healthy red blood cells, leading to a deficiency of red blood cells, known as anemia.

Sickle-cell anemia is an autosomal recessive genetic disease—that is, a child with the disease must inherit one copy of the defective hemoglobin gene from each parent. Many people carry one hemoglobin S gene with no significant health problems as a result. But these carriers of the sickle-cell gene can pass the gene to their children. When both parents are carriers, they have a one in four chance with every pregnancy of having a child with sickle-cell anemia.

Scurvy

Scurvy, disease of human beings caused by a prolonged deficiency of vitamin C, or ascorbic acid, in the diet. It is characterized by progressive bodily weakness, spongy and inflamed gums, loose teeth, swollen and tender joints, and a tendency toward ecchymosis, or absorption by the tissues of blood from ruptured blood vessels. Anemia often occurs as a direct result of such hemorrhage. Lack of vitamin C in the diet prevents the formation of connective tissues that hold the body's structures together, such as tendons, ligaments, bone, dentin, and cartilage. The disease may appear in adults after about six months of complete lack of vitamin C.

Schistosomiasis

Schistosomiasis or Bilharziasis, widespread disease caused by the infestation of the human body by (flukes) commonly called blood flukes, of the genus Schistosoma. Blood flukes spend most of their life cycle in two hosts; the adult stage is spent in a mammal, usually humans, and the immature stages are spent in certain snails. Eggs discharged from the host hatch into larval forms in fresh water; from the water, the larvae, miracidia, invade the snail that acts as an intermediate host. The larval form of the parasite undergoes partial maturation in the snail, then escapes back into the water, as mature larvae called cercariae. At this stage they penetrate the skin of the host from the water and then migrate through the blood vessels to specific capillaries as maturation completes. There they remain and lay eggs.

Rickets

Rickets, nutritional disorder characterized by skeletal deformities. Rickets is caused by a decreased concentration of the mineral hydroxyapatite in bones and cartilage due to low levels of calcium and phosphorus in the blood. Vitamin D is essential for the maintenance of normal calcium and phosphorus levels. Classic rickets, a deficiency disease of children characterized by improper development or hardening of bones, is due to lack of sufficient vitamin D in the diet, or to insufficient ultraviolet radiation from direct sunlight, a lack that prevents conversion of the element 7-dehydrocholesterol in the skin to vitamin D. The type of skeletal deformities depends largely on the child's age when the vitamin-D deficiency occurs. A child who has not yet learned to walk develops vertebral curvatures; a walking child develops leg curvatures.

Riboflavin

Riboflavin, also called vitamin B2 or vitamin G, a substance essential for the breakdown and utilization of carbohydrates, fats, and proteins in the body, and in the production of energy. Riboflavin plays a vital role in the health of the skin and is needed for production of certain hormones by the adrenal glands, the pair of hormone-secreting organs that sit on top of each kidney. Because it is a water-soluble vitamin—that is, it is not stored in the body, but is excreted in sweat or urine—riboflavin needs to be constantly replaced in the body.

Rich sources of riboflavin include milk, cheese and yogurt, lean meat, liver, green leafy vegetables, eggs, and enriched breads and cereals. Because cheese and milk are such good dietary sources of the vitamin, lactose-intolerant people, including many of the elderly, are vulnerable to deficiency problems. Individuals who exercise often, especially women, are also at risk for riboflavin deficiency. A lack of riboflavin in the diet may result in inflammation, scaling, and blistering of the skin—symptoms characteristic of such conditions as dermatitis and eczema. Other problems can include general fatigue, burning eyes, cracks and sores in mouth and on the lips, and digestive problems.

Tracheotomy

Tracheotomy, surgical operation in which an incision, or opening, is cut through the front of the neck and into the trachea, or windpipe. The oldest mention of the operation in medical literature is found in the writings of the Greek physician Galen (2nd century ad).

A tracheotomy creates an alternate passage to the lungs for air that cannot flow from the nose and mouth through the trachea because of an obstruction. Obstructions may occur when a foreign body lodges in the larynx, or voice box, above the trachea; as a result of swelling or spasm of the larynx or vocal cords; or from infection and swelling of the epiglottis, the thin flap of cartilage covering that keeps food and liquid out of the trachea.

The purpose of a tracheostomy is to keep the airway from closing prematurely and to enable the physician to take further measures, if necessary, to ensure that the patient has a patent airway. When a tracheotomy is performed on a patient suffering from severe bronchial or lung congestion, a catheter, or small-diameter, flexible tube, is inserted through the stationary tube and used with a suction device to clean out the bronchial tubes and lungs while the patient is encouraged to cough vigorously.

Syringe

Syringe, device used to eject or collect fluids. A syringe consists of a hollow barrel made of glass, plastic, or metal with a close-fitting plunger or a rubber bulb on one end. The other end of the barrel has a nozzle which may be designed to accept a needle or other attachment. The barrel fills by suction when the plunger is pulled out, or when the bulb is compressed and subsequently allowed to inflate. Pushing in the plunger or squeezing the bulb forces the fluid out through the needle or nozzle.

Syringes come in many sizes and serve many purposes. The small syringe used in medicine to give hypodermic injections (forceful introduction of medication or fluid beneath the skin) has a plunger and a fine hollow needle. Its barrel is calibrated, featuring a set of equally spaced marks that measure the volume of its contents. The larger medical syringes used to cleanse wounds or body cavities, or to extract unwanted fluids from the body, have wider, flexible nozzles on one end and rubber bulbs on the other end.

Sharing unsterilized syringes can cause serious health problems. Human immunodeficiency virus (HIV), which may lead to acquired immunodeficiency syndrome (AIDS), has been spread by infected substance abusers who share the same syringe to inject intravenous drugs. The viruses that cause hepatitis A and hepatitis B, both of which inflame the liver, are also commonly transmitted through the use of shared needles and syringes.

Phobia

Phobia, intense and persistent fear of a specific object, situation, or activity. Because of this intense and persistent fear, the phobic person often leads a constricted life. The anxiety is typically out of proportion to the real situation, and the victim is fully aware that the fear is irrational.

Behavioral techniques have proved successful in treating phobias, especially simple and social phobias. One technique, systematic desensitization, involves gradually confronting the phobic person with situations or objects that are increasingly close to the feared ones. Exposure therapy, another behavioral method, has recently been shown more effective. In this technique, phobics are repeatedly exposed to the feared situation or object so that they can see that no harm befalls them; the fear gradually fades. Antianxiety drugs have also been used as palliatives. Antidepressant drugs have also proved successful in treating some phobias.

Phenytoin

Phenytoin or Dilantin, drug used to treat the seizures, or violent muscle contractions, caused by epilepsy. The drug can also control seizures associated with surgery of the brain or spinal cord. Phenytoin influences the movement of sodium along nerve fibers, preventing or minimizing the abnormal electrical impulses that cause seizures.

Phenytoin is available by prescription in tablet, capsule, and liquid form. Taken orally, except for one liquid form made for injection, the drug is usually prescribed in 100-mg doses taken once a day. The maximum recommended daily dosage is 600 mg. To avoid stomach irritation, oral phenytoin should be taken with food. The drug’s effectiveness is usually apparent after two to three weeks of treatment.

Patients with impaired liver function, diabetes, or heart disease should use this drug with caution. Although long-term use of phenytoin is common, it may be associated with the development of cancers in the lymphatic system or the bone marrow (leukemia). Pregnant women or those nursing an infant should not take this drug. Children who take it should be monitored with particular care.

Possible side effects include decreased coordination, mental confusion, or slurred speech. Other observed side effects include nausea, headache, fever, dizziness, twitching, involuntary eye movement, joint pain, insomnia, impotence, bedwetting, abnormal hair growth, skin rash, or change in urine color. An overdose of phenytoin can be fatal. Abruptly stopping treatment can cause uninterrupted seizures that may also be fatal.

Phenytoin may interact adversely with a variety of medications. These include, but are not limited to, aspirin, certain tranquilizers, steroids, blood thinners, ulcer medications, oral contraceptives, estrogens, and antacids. Also included are the drugs felbamate, furosemide, methylphenidate, phenobarbital, carbamazepine, diazepam, doxycycline, sodium valproate, theophylline, and valproic acid. Users of phenytoin should not drink alcoholic beverages.

Brand Name:Dilantin

Pelvic Inflammatory Disease

Pelvic Inflammatory Disease (PID), bacterial infection of the upper female genital tract, including the uterus, fallopian tubes, and ovaries. PID can be caused by several different aerobic (oxygen-requiring) and anaerobic (non-oxygen-requiring) bacteria. The two most important such bacteria are Neisseria gonorrhoeae, the bacterium that causes gonorrhea, and Chlamydia trachomatis, the bacterium that causes chlamydia. These bacteria are usually transmitted through sexual intercourse with an infected partner.

The usual symptoms of acute PID are fever, chills, lower abdominal and pelvic pain, and vaginal discharge or bleeding. These symptoms often begin a few days after the start of a menstrual period, particularly when Neisseria gonorrhoeae is the cause of infection. Infections due to Chlamydia trachomatis usually progress more slowly than those caused by Neisseria gonorrhoeae. On physical examination by a doctor, the uterus, ovaries, and fallopian tubes of the infected person are usually tender. In severe cases, an abscess may be present in the pelvis. Complications from PID occur in one out of four infected women and include tuboovarian abscess, Fitz-Hugh-Curtis syndrome (inflammation surrounding the liver), chronic pelvic pain, and occasionally death. In addition, PID is the single most important risk factor for ectopic pregnancy.and one of the most common causes of female infertility.

Antibiotic therapy is the usual treatment for PID. Most women take oral antibiotics such as intramuscular ceftriaxone, and oral doxycycline and metronidazole for a period of 10 to 14 days, after which they are cured. Women who are severely ill are usually treated with intravenous antibiotic therapy in the hospital. A woman's sexual partner should also be treated with antibiotics.

Paralysis

Paralysis, loss of voluntary movement in a part of the human body, caused by disease or injury anywhere along the motor-nerve path from the brain to the muscle fiber. Paralysis may result from injury, poisoning, infection, hemorrhage, occluded blood vessels, or tumors. Occasionally paralysis is due to congenital deficiency in motor-nerve development. Permanent paralysis results from extensive damage to nerve cells or to a nerve trunk; severely damaged nerve cells cannot regenerate. Transient or incomplete paralysis, called paresis, is often caused by infections, trauma, or poisons that temporarily suppress motor activity but do not extensively damage nerve cells.

Because most of the motor nerves from either half of the brain supply the opposite side of the body, lesions in one part of the brain usually produce paralyses in the opposite half of the body. Paralysis of one limb is known as monoplegia; paralysis of two limbs on the same side of the body as hemiplegia; paralysis of both lower limbs as paraplegia or diplegia; and paralysis of all four limbs as quadriplegia or tetraplegia. Paralysis originating in the brain may sometimes be flaccid, that is, the affected muscles may be loose, weak, flabby, and without normal reflexes. More frequently it is spastic, that is, the affected muscles are rigid and the reflexes accentuated. Paralysis originating in a motor nerve of the spinal cord is always spastic; paralysis originating in peripheral nerves or thin ganglion cells is always flaccid.

Among well-known paralytic conditions are poliomyelitis (previously known as infantile paralysis), cerebral palsy, and multiple sclerosis. Bell's palsy is a common facial paralysis, generally temporary and produced by such conditions as neuritis or infection. Locomotor ataxia is a paralytic condition caused by infestation of the spinal cord and brain with microorganisms that cause syphilis. Alcoholic paralysis is caused by degeneration of nerve cells, in the spinal cord or, less often, in the brain, which have been deprived of essential nutrients.

Temporary paralyses are treated by removing the underlying cause. Permanent paralyses may be ameliorated by appropriate physical therapy and rehabilitation procedures.

Panic Disorder

Panic Disorder, mental illness in which a person experiences repeated, unexpected panic attacks and persistent anxiety about the possibility that the panic attacks will recur. A panic attack is a period of intense fear, apprehension, or discomfort. In panic disorder, the attacks usually occur without warning. Symptoms include a racing heart, shortness of breath, trembling, choking or smothering sensations, and fears of “going crazy,” losing control, or dying from a heart attack. Panic attacks may last from a few seconds to several hours. Most peak within 10 minutes and end within 20 or 30 minutes.

Pain

Pain, unpleasant sensory and emotional experience caused by real or potential injury or damage to the body or described in terms of such damage. Scientists believe that pain evolved in the animal kingdom as a valuable three-part warning system. First, it warns of injury. Second, pain protects against further injury by causing a reflexive withdrawal from the source of injury. Finally, pain leads to a period of reduced activity, enabling injuries to heal more efficiently.

Pain is difficult to measure in humans because it has an emotional, or psychological component as well as a physical component. Some people express extreme discomfort from relatively small injuries, while others show little or no pain even after suffering severe injury. Sometimes pain is present even though no injury is apparent at all, or pain lingers long after an injury appears to have healed.

Osteoporosis

Osteoporosis, bone condition characterized by a decrease in mass, resulting in bones that are more porous and more easily fractured than normal bones. Fractures of the wrist, spine, and hip are most common; however, all bones can be affected. White females are the most susceptible, but other risk factors include low calcium intake; inadequate physical activity; certain drugs, such as corticosteroids, and a family history of the disease.

The most common form of the disease, primary osteoporosis, includes postmenopausal (see Menopause), or estrogen-deficient, osteoporosis (Type I), which is observed in women whose ovaries have ceased to produce the hormone estrogen; age-related osteoporosis (Type II), which affects those over the age of 70; and idiopathic osteoporosis, a rare disorder of unknown cause that affects premenopausal women and men who are middle-aged or younger. Secondary osteoporosis may be caused by bone disuse as a result of paralysis or other conditions, including weightlessness in space; endocrine and nutritional disorders, including anorexia nervosa; specific disease processes; and certain drug therapies.

Prevention and treatment of osteoporosis include synthetic estrogen or progestin therapy or both for postmenopausal women, intake of calcium and other nutrients, weight-bearing exercise, and drugs such as calcitonin and alendronate sodium, a nonhormonal treatment for osteoporosis.

Osteomyelitis

Osteomyelitis, term applied to any inflammation of bone or bone marrow, usually caused by infection by such microorganisms as Staphylococcus aureus, various streptococci, Mycobacterium tuberculosis, and a host of others, as well as several fungi. The microorganisms generally reach the bone through the bloodstream from infection elsewhere. Occasionally osteomyelitis occurs by direct infection after surgery, after a compound fracture, or as a result of trauma.

Osteomyelitis, especially bacterial, may occur as an acute disease. Common symptoms include chills followed by fever, with acute pain and swelling above the site of inflammation. The inflammation begins in the marrow cavity and causes softening and erosion of the long bones, often with the formation of pus-containing abscesses, and soon spreads over the entire bone, with consequent death of the hard portions of the bone.

Chronic osteomyelitis, as is often seen in tuberculosis, fungus infections, or in patients with bacterial infections from other organisms, tends to run a slower and less dramatic course, with less severe pain and less fever, often resulting in bone destruction.

Acute osteomyelitis is treated by injections of antibiotics such as nafcillin, and by concurrent surgery to open the affected bone and drain the pus and dead tissue. Because of antibiotics, severe acute osteomyelitis is rare.

Obsessive-Compulsive Disorder

Obsessive-Compulsive Disorder, mental illness in which a person experiences recurrent, intrusive thoughts (obsessions) and feels compelled to perform certain behaviors (compulsions) again and again. Most people have experienced bizarre or inappropriate thoughts and have engaged in repetitive behaviors at times. However, people with obsessive-compulsive disorder find that their disturbing thoughts and behaviors consume large amounts of time, cause them anxiety and distress, and interfere with their ability to function at work and in social activities. Most people with this disorder recognize that their obsessions and compulsions are irrational but cannot suppress them.

Treatment for obsessive-compulsive disorder includes psychotherapy, psychoactive drugs, or both. Mental health professionals consider exposure and response prevention, a type of cognitive-behavioral therapy, to be the most effective form of psychotherapy for this disorder.

Medications to treat obsessive-compulsive disorder include selective serotonin reuptake inhibitors, such as fluoxetine (Prozac) and fluvoxamine (Luvox). A tricyclic antidepressant, clomipramine (Anafranil), also helps relieve symptoms of the disorder.

Obesity

Obesity, medical condition characterized by storage of excess body fat. The human body naturally stores fat tissue under the skin and around organs and joints. Fat is critical for good health because it is a source of energy when the body lacks the energy necessary to sustain life processes, and it provides insulation and protection for internal organs. But the accumulation of too much fat in the body is associated with a variety of health problems.

A calorie is the unit used to measure the energy value of food and the energy used by the body to maintain normal functions. When the calories from food intake equal the calories of energy the body uses, weight remains constant. But when a person consumes more calories than the body needs, the body stores those additional calories as fat, causing subsequent weight gain. Consuming about 3,500 calories more than what the body needs results in a weight gain of 0.45 kg (1 lb) of fat.

Obesity can become a chronic lifelong condition caused by overeating, physical inactivity, and even genetic makeup. No matter what the cause, however, obesity can be prevented or managed with a combination of diet, exercise, behavior modification, and in severe cases, weight-loss medications and surgery.

Neuritis

Neuritis, inflammation of peripheral nerves, characterized by sensory or motor disturbances that may take the form of pain (often burning), numbness, tingling (or pins-and-needles) sensations, hypersensitivity, or anesthesia, in the area supplied by the involved nerve; weakness or paralysis of the muscles innervated by the involved nerve may also take place. It is generally the result of such localized causes as injuries, pressure from arthritis involving the spine at the area where the nerve root exits, adjacent tumors, or prolonged exposure to extreme cold. Neuritis may also involve several nerves in different parts of the body. This type of neuritis usually affects the extremities. Infectious diseases, such as typhoid fever, malaria, syphilis, or tuberculosis, and diabetes, heavy-metal poisoning, alcoholism, vitamin deficiencies associated with pregnancy, beriberi, and pellagra are among the causes of certain types of neuritis.

Neuralgia

Neuralgia, recurrent pain along the path of a sensory nerve. Neuralgia may be caused by a disorder that affects a nerve, such as tooth decay or carpal tunnel syndrome, or it may accompany such diseases as diabetes mellitus or certain vitamin deficiencies. In some cases the cause of neuralgia cannot be determined. Whatever the cause, the affected nerve does not become inflamed and its tissues are not damaged or destroyed.

Trigeminal neuralgia is one of the most common forms of neuralgia, involving the trigeminal nerve, which carries sensation from the face, eyes, nose, mouth, and jaws to the brain. Trigeminal neuralgia is characterized by overwhelming sensations of stabbing pain that may be momentary or may last for minutes or hours. When it is short-lived, the condition is also known as tic douloureux. Trigeminal neuralgia may be relieved by analgesics such as aspirin, ibuprofen, and acetaminophen. In severe cases, surgery may be performed to reduce pressure on the nerve or to sever it.

In postherpetic neuralgia, pain occurs at a site earlier affected by herpes zoster, or shingles, in which blisters develop on the skin along the path of a nerve. Postherpetic neuralgia may last for weeks or months after the illness, but the pain may be alleviated with analgesics.

Myasthenia Gravis

Myasthenia Gravis, chronic disease marked by progressive weakness and abnormally rapid fatigue of the voluntary muscles. The muscles affected include those used in walking, breathing, chewing, and talking. A characteristic sign of the disease is drooping eyelids. Myasthenia gravis most often affects women between the ages of 20 and 30, but it can strike anyone after adolescence; after 40, it actually afflicts more men than women.

Myasthenia gravis is a noninherited autoimmune disease characterized by the presence of antibodies in the blood that destroy muscle-cell sites for the reception of acetylcholine molecules. Acetylcholine normally transmits signals between nerves and muscles, so when its receptors are destroyed it cannot induce muscle contractions. No cure for the disease yet exists, but it can be treated with drugs called anticholinesterases. These drugs are capable of inhibiting an enzyme, acetylcholinesterase, that breaks down acetylcholine in the body. Myasthenia gravis may also be relieved by surgical removal of the thymus and by a blood-cleansing process called plasmapheresis that eliminates the destructive antibodies.

Muscular Dystrophy

Muscular Dystrophy, crippling disease characterized by gradual wasting of skeletal muscle. As the disease progresses, symptoms include increased weakness and loss of muscle mass and function. Eventually a person with muscular dystrophy needs to use a wheelchair to move around. Four clinical forms of the disease are recognized, based on pattern of inheritance, age when symptoms are first noted, and distribution of the muscles earliest involved. Microscopic abnormalities of skeletal muscle are found in each type.

Muscular dystrophy has its origin in a genetic mutation, but the biochemical steps by which this genetic defect manifests itself in the degenerative process in the muscle are not known. Because specific treatment is not available, general measures, including physical and occupational therapy, are used. Genetic tests for mutations in the different genes causing muscular dystrophy provide rapid and accurate diagnosis for patients.

Malnutrition

Malnutrition, dietary condition caused by a deficiency or excess of one or more essential nutrients in the diet. Malnutrition is characterized by a wide array of health problems, including extreme weight loss, stunted growth, weakened resistance to infection, and impairment of intellect. Severe cases of malnutrition can lead to death. Deficiency diseases are usually associated with lack of vitamins or minerals. The effects of a vitamin or mineral deficiency on the body depend on the function of the particular nutrient lacking. For example, vitamin A is important for good vision, and severe deficiency of this vitamin may cause blindness. Because some vitamins and minerals have many functions, prolonged nutritional deficiencies can therefore have wide-ranging effects on health. Diets that lack a wide variety of foods may result in vitamin deficiency diseases. For example, in countries where people eat maize as the staple food and only few other foods, diets may lack niacin, a B vitamin. Such diets may cause pellagra, a deficiency disease characterized by dermatitis, diarrhea, and dementia.

Ketorolac

Ketorolac, non-steroidal anti-inflammatory drug used in the short-term management of severe, acute pain, as well as for the short-term treatment of itchy eyes caused by seasonal allergies. Ketorolac relieves pain and reduces fever and inflammation by blocking the production of prostaglandins. It is sometimes used with a narcotic to provide better pain relief than either drug alone can offer.

This drug is available by prescription only as an injectable liquid, tablets and eye drops. The effectiveness of all forms is usually apparent in 30 to 60 minutes.

Ketorolac should be used with caution by patients with known bleeding disorders or sensitivities to other non-steroidal anti-inflammatory drugs as well as by patients with a history of alcohol abuse, diabetes mellitus, edema, kidney or liver disease, lupus erythematosus, asthma, colitis, heart disease, or high blood pressure. The safety of this drug for pregnant or breast-feeding women or for children has not been determined. The eyedrop solution should not be used by patients wearing contact lenses. Abdominal or stomach pain, bruising at the site of injection, drowsiness, indigestion, and nausea are the most common side effects of both the oral and injected forms of the drug. Less common side effects are bloating or gas, burning or pain at the injection site, constipation, diarrhea, dizziness, a feeling of fullness in the abdominal or stomach area, headache, increased sweating, vomiting, edema, decrease in urine output, renal failure, and gastrointestinal bleeding, ulceration, and perforation.

A temporary stinging and burning sensation in the eye is the most common side effect of the eyedrop solution. Less common side effects are eye irritation, allergic reactions, superficial eye infections, and superficial inflammation of the eye’s cornea.

Ketorolac may interact adversely with aspirin, acetaminophen, and other non-steroidal anti-inflammatory agents, as well as with lithium, methotrexate, probenecid, ketoprofen, nabumetone, naproxen, and oxaprozin. Use of ketorolac with blood-thinning drugs, cefamandole, cefoperazone, cefotetan, heparin, moxalactam, plicamycin, or valproic acid may increase risk of bleeding.

Brand Names: Acular, Toradol

Ketoprofen

Ketoprofen, drug used to reduce the inflammation, fever, and pain associated with such diseases as arthritis, bursitis, tendinitis, and menstrual cramps. Ketoprofen is believed to work by preventing prostaglandins (chemicals that cause inflammation and contribute to the brain’s perception of pain) from concentrating in body tissues.

Ketoprofen is available by prescription in capsule, tablet, and suppository form. The drug is taken daily in 3 or 4 doses for a total of 150 to 300 mg. It is most effectively absorbed if taken on an empty stomach, but it can be taken with food, milk, or an antacid to prevent stomach irritation. The patient must take ketoprofen for one to three weeks before physicians can evaluate its effectiveness.

Possible side effects include drowsiness, fluid retention, skin rash, headache, depression, indigestion, and nausea. Men may experience problems with sexual performance and breast enlargement. Women may find their menstrual cycles affected, with increased blood flow during menstruation.

Pregnant women should not use ketoprofen in the third trimester of pregnancy. Breast-feeding women, patients with allergies to the drug, those who suffer asthma with aspirin use, and patients with ulcers, bleeding disorders, impaired kidney function, or liver disease should not take ketoprofen.

Ketoprofen may have negative effects when taken with other anti-inflammatory drugs, steroids, aspirin, insulin, phenytoin, verapamil, nifedipine, lithium, and diuretics. Alcoholic beverages can increase the risk of ulcers or bleeding in the stomach.

Brand Name: Orudis

Ketoconazole

Ketoconazole, prescription drug used to treat fungal infections. It works by weakening fungal cell walls, thereby either killing the fungus or stopping its growth. Ketoconazole is also used to treat prostate cancer because it suppresses the production of testosterone, a hormone necessary for prostate cancer cell survival.

Ketoconazole is available as a tablet, cream, or shampoo. Patients using the drug in tablet form take 200 to 400 mg once a day for fungal infections and 400 mg three times a day for prostate cancer. The drug should be taken with food for better absorption and to avoid stomach irritation. It must be taken for two to four weeks before a physician can evaluate its effectiveness as an antifungal agent. A cure may require many months of treatment.

Common side effects of ketoconazole include reduced testosterone production (which may impair sexual function in males), skin irritation and rash, headache, nausea, diarrhea, and liver problems. Pregnant and nursing women, patients with active liver disease, and patients who have previously had an allergic reaction to the drug should not take ketoconazole. Patients should exercise caution in taking the drug if they are allergic to related antifungal drugs, take any other drugs, have liver disease or reduced liver function, have a history of alcoholism, or have low levels of hydrochloric acid in their stomachs.

Ketoconazole enhances the blood-thinning effects of warfarin and minimizes the effects of theophylline. Antacids may lessen ketoconazole’s effectiveness. Patients who consume alcohol while taking this drug may experience dizziness, headaches, and nausea. Alcohol in combination with ketoconazole can also contribute to liver problems.

Brand Name:Nizoral

Irritable Bowel Syndrome

Irritable Bowel Syndrome (IBS), also known as spastic colon, recurring symptoms of constipation, diarrhea, and abdominal cramping that appear without a clear cause

The diarrhea associated with IBS is not true diarrhea in that there is no increase in stool volume. Patients sometimes pass mucus with the stools and have a sensation of incomplete evacuation of the bowels following defecation.

Recurring IBS has been associated with stress, although abdominal distress is a common reaction to anxiety in many people who do not suffer from IBS.

Physicians diagnose IBS only after conducting a series of tests that rule out other gastrointestinal disorders, such as inflammatory bowel disease, intestinal parasites, and polyps. These tests include a barium enema, stool parasite culture, and sigmoidoscopy, examination of the lower intestines with a hollow, tubelike instrument passed through the anus.

There is no cure for IBS and treatment focuses on alleviating symptoms. High fiber diets or antispasmodic drugs may relieve constipation, and antidiarrheal drugs may alleviate prolonged diarrhea. Although there is no scientific evidence linking irritable bowel syndrome and the amount of fiber in the diet, some people benefit from eating a high-fiber diet, while others find reducing their carbohydrate intake helps.

Influenza

Influenza, also known as flu, contagious infection primarily of the respiratory tract. Influenza is sometimes referred to as grippe. Influenza is caused by a virus transmitted from one person to another in droplets coughed or sneezed into the air. It is characterized by coldlike symptoms plus chills, fever, headaches, muscle aches, and fatigue. Most people recover completely in about a week. But some people are vulnerable to complications such as bronchitis and pneumonia. This group includes children with asthma, people with heart or lung disease, and the elderly.

Influenza is an acute disease with a rapid onset and pronounced symptoms. After the influenza virus invades a person’s body, an incubation period of one to two days passes before symptoms appear. Classic symptoms include sore throat, dry cough, stuffed or runny nose, chills, fever with temperatures as high as 39º C (103º F), aching muscles and joints, headache, loss of appetite, occasional nausea and vomiting, and fatigue. For most people flu symptoms begin to subside after two to three days and disappear in seven to ten days. However, coughing and fatigue may persist for two or more weeks.

There is no specific cure for influenza. Recommended treatment usually consists of bed rest and increased intake of nonalcoholic fluids until fever and other symptoms lessen in severity. Certain drugs have been found effective in lessening flu symptoms, but medical efforts against the disease focus chiefly on prevention by means of vaccines that create immunity.

Impetigo

Impetigo, contagious skin disease, which commonly appears in young children and infants, although adults may be affected. Usually caused by group A streptococci or by staphylococci, it appears on such exposed parts of the skin as the face, hands, arms, and legs and is spread to adjacent areas by scratching. It also spreads readily to other people by direct contact or by contact with articles used by the infected person.

The infection produces pus-filled blisters that rupture and harden to form yellow crusts, from which fluid may ooze. Treatment consists of removing the crusts with soap and water and applying ointments containing antibiotics. When treated promptly, impetigo usually heals within a week without leaving scars.

Hypothermia

Hypothermia, condition in which body temperature falls drastically as a result of exposure to cold. It may occur, for example, in hikers caught in a sudden cold front without sufficient clothing. The elderly can die from hypothermia at temperatures that would not harm younger persons. The condition involves a paradoxical response to sudden cold: the shutting off of blood flow to the body's surface. First aid may involve wrapping the victim in blankets (along with the rescuer, if necessary). Despite customary belief, alcohol causes loss of heat and should not be given. Treatment at a hospital involves slowly raising the body temperature by various means.

Hypothermia may also be induced for medical purposes. Reduction in body temperature causes a slowing of the metabolism. This is useful in certain types of surgery and to reduce bleeding in a particular part of the body.

Hodgkin’s Disease

Hodgkin’s Disease or Hodgkin's Lymphoma, less severe form of two types of cancer that arise in the lymphatic system (network of small vessels that carry lymph, a fluid containing white blood cells of the immune system). The other form is non-Hodgkin's lymphoma. Hodgkin's disease is characterized by usually painless but progressive enlargement of lymph nodes (or glands) and other lymphoid tissue.

Diagnosis of Hodgkin's disease is made with a biopsy (removal of a small tissue sample for examination under a microscope). Hodgkin's disease is primarily distinguished from non-Hodgkin's lymphoma by the presence of Reed-Sternberg cells, large cells that contain several nuclei. If the disease is diagnosed at an early stage and has not metastasized (spread to other areas of the body), radiation therapy is commonly used. With advanced cases, the doctor will usually prescribe chemotherapy (anti-cancer drugs) for approximately six months, often in combination with radiation therapy. For patients with disease resistant to conventional treatments, or for patients who have relapses (reappearance of symptoms after an apparent cure), doctors may try high-dose chemotherapy and bone-marrow transplants. The chemotherapy destroys all of the patient's unhealthy bone marrow in preparation for the transplantation of healthy bone marrow, so the body can once again produce healthy white blood cells. The healthy bone marrow is injected into the bloodstream and, if successful, the cells find their way to the bones and begin to grow

Heparin

Heparin, substance produced by cells of the liver, lungs, and intestines that keeps blood from clotting. It normally inhibits the clotting of blood by interfering with the production of thrombin, an enzyme necessary for clot formation. Heparin obtained from animals is administered after surgery to reduce the risk of thrombosis, the formation of a blood clot in a blood vessel. It is also used after pulmonary embolism to ensure that no further clots form, as well as during kidney dialysis.

Ulcer

Ulcer, shallow sore produced by the destruction of skin or mucous membrane. Skin ulcers may occur in association with a number of chronic illnesses, such as diabetes, kidney and heart ailments, varicose veins, syphilis, leprosy, tuberculosis, and cancer. Gastrointestinal ulcers occur with chronic gastritis, ulcerative colitis, and typhoid fever.

Peptic ulcers are ulcers of the stomach (gastric) or small intestine (duodenal). In addition to the pain caused by the ulcer itself, peptic ulcers give rise to such complications as hemorrhage from the erosion of a major blood vessel; perforation of the wall of the stomach or intestine, with resultant peritonitis; or obstruction of the gastrointestinal tract because of spasm or swelling in the area of the ulcer.

The direct cause of peptic ulcers is the destruction of the gastric or intestinal mucosal lining by hydrochloric acid, an acid normally present in the digestive juices of the stomach. Infection with the bacterium Helicobacter pylori is thought to play an important role in causing both gastric and duodenal ulcers. Injury of the gastric mucosal lining, and weakening of the mucous defenses such as by nonsteroidal anti-inflammatory drugs, are also responsible for gastric ulcer formation. Excess secretion of hydrochloric acid, genetic predisposition, cigarette smoking, and psychological stress are important contributing factors in duodenal ulcer formation and exacerbation.

Several different types of prescription drugs are used in the treatment of ulcers. Antacids may be ingested to neutralize the hydrochloric acid secretions. Drugs such as cimetidine and ranitidine block the action of histamine, the body chemical that triggers acid secretion, and have been shown to induce healing of ulcers in many patients. Omeprazole inhibits acid secretion by disabling the cellular pumps that pump acid into the stomach. Bismuth-containing compounds and antibiotics may be used to eradicate Helicobacter pylori infection, accelerating healing and reducing the rate of ulcer recurrence. Sucralfate forms a protective layer that enhances the mucosal lining of the stomach and intestines. Misoprostol is effective against gastric ulcers caused by nonsteroidal anti-inflammatory drugs. Quitting smoking can also accelerate the healing process. Alcohol and caffeine should be avoided, although in general a bland diet is of no benefit. In extreme cases surgery may be required.

Hemorrhage

Hemorrhage, excessive discharge of blood from blood vessels, caused by pathological condition of the vessels or by traumatic rupture of one or more vessels. Hemorrhage is a complication of many diseases. Peptic ulcer, for example, may cause hemorrhage by eroding a blood vessel. Stroke is sometimes due to hemorrhage in the brain. Hemophilia, a hereditary blood disease, is characterized by failure of the blood to coagulate. Sudden loss of more than about 1 liter (1 qt) of blood may lead to shock; unless the blood is replaced by transfusion, this shock can be fatal.

Bleeding normally stops through the process of coagulation, or clotting of the blood, and methods used to stop hemorrhage depend on stanching the flow of blood sufficiently for a clot to form. The hemorrhage is most effectively stopped by the application of pressure directly over the wound. Bleeding is also lessened by placing the body so that the wound is uppermost. A tourniquet should never be applied if there is another way to stop the bleeding, as application of a tourniquet increases the likelihood that amputation will be required.

Fibrin film and fibrin foam, plastics made from the blood protein fibrinogen, are extensively used in surgery. Fibrin foam is used in the form of a surgical sponge that rapidly stops bleeding by forming clots. Fibrin film is used to wrap nerves or tendons or as a membrane to cover the brain or other organs. Fibrin may be left without harm in the body, where it slowly dissolves.

Heartburn

Heartburn, condition characterized by a burning feeling in the chest and a sour or bitter taste in the mouth. Heartburn typically develops when the acidic contents of the stomach flow back, or regurgitate, into the esophagus, the muscular tube that carries food from the throat to the stomach.

Heartburn is generally diagnosed with a complete description of the symptoms. In severe cases, a physician may order a barium X ray of the stomach and esophagus to rule out other problems. Alternatively, a physician may examine the esophagus with an endoscope, an instrument that can view the interior of the digestive tract, and take tissue and fluid samples.

Treatments for heartburn in mild cases, over-the-counter medications such as antacids can relieve occasional bouts. Chronic heartburn can be treated with medications that prevent the production of acid in the stomach.

Lifestyle changes, such as quitting smoking or losing weight, also can alleviate or prevent heartburn. Sleeping with the head of the bed elevated 15 cm (6 in) helps prevent the stomach's contents from flowing back into the esophagus. Going to bed on an empty stomach, and cutting back on consumption of alcohol, fat, chocolate, and peppermint also can prevent heartburn.

Pravastatin

Pravastatin, drug used to lower cholesterol levels in the bloodstream in cases when dietary changes, weight loss, and exercise are ineffective in lowering cholesterol. Pravastatin works by blocking the liver enzyme that controls the manufacture of cholesterol. It is primarily effective against low-density lipoproteins (LDL), the form of cholesterol associated with increased risk of heart disease.

Available only by prescription, tablets of pravastatin are taken with or without food, usually at bedtime. The typical dosage ranges between 10 and 40 mg per day. Typically, cholesterol levels begin falling four to six weeks after the medication is started. Pravastatin is often prescribed in combination with a cholesterol-lowering diet.

Pregnant or nursing women, or children under the age of 18, should not take pravastatin. Patients with liver or kidney disease, muscular disorders, cataracts, or a history of alcohol abuse should use this drug with caution. Pravastatin can cause damage to the liver or muscle tissue, although problems can usually be detected early using well-established laboratory tests.

Possible side effects of this drug include dizziness, headache, skin rash, itchiness, stomach pain, nausea, diarrhea, constipation, gas, muscle cramps, or flulike symptoms. Pravastatin may be contraindicated for patients who are also taking the following drugs: cholestyramine, cimetidine, colestipol, cyclosporine, erythromycin, gemfibrozil, ketoconazole, niacin, warfarin, and immunosuppressive drugs.

Brand Name: Pravachol

Simvastatin

Simvastatin, drug used to lower cholesterol levels. It is typically prescribed by a physician when dietary changes, weight loss, and exercise are not effective in reducing cholesterol. Simvastatin works by blocking the liver enzyme that controls the production of cholesterol. It is primarily effective against low-density lipoproteins (LDL), the form of cholesterol associated with increased risk of coronary heart disease.

Tablets are taken with or without food, usually at bedtime. The typical dosage ranges between 5 and 40 mg per day. Effectiveness is usually apparent after four to six weeks of treatment. Simvastatin is usually prescribed in combination with a cholesterol-lowering diet.

This drug should not be taken by patients with liver disease, by pregnant or nursing women, or by young people under the age of 20. Patients with impaired liver function, muscular disorders, cataracts, or a history of alcohol abuse should use this drug with caution.

Possible side effects of this drug include headache, stomach pain, nausea, diarrhea, constipation, gas, muscle weakness, or lowered blood pressure. Other side effects sometimes observed are muscle pain, skin rash, impaired vision, or hepatitis. Simvastatin may interact adversely with the drugs cholestyramine, cimetidine, clofibrate, cyclosporine, erythromycin, gemfibrozil, digoxin, ketoconazole, nicotinic acid, warfarin, and spironolactone.

Brand Name:Zocor

Lovastatin

Lovastatin, drug used to reduce high blood cholesterol levels and slow the progression of coronary atherosclerosis, or hardening of the heart’s arteries. Lovastatin interferes with an enzyme in the liver responsible for making cholesterol, a fatlike substance that can both harden and clog the arteries. This drug reduces low-density lipoproteins (LDL), the type of cholesterol that increases the risk of coronary heart disease, and increases high-density lipoproteins (HDL), the type of cholesterol thought to reduce the risk of heart disease.

Available by prescription only, this drug is dispensed in 10-mg, 20-mg, and 40-mg tablets, which are taken orally. The initial adult dosage is 20 mg taken once a day, after which the dosage may be increased up to 40 mg twice a day. The maximum dosage should not exceed 80 mg daily. Effectiveness should be apparent within two weeks.

This drug should be taken with food, preferably with evening meals. It should not be used by persons who have had an allergic reaction to lovastatin; persons with active liver disease or active peptic ulcers; or pregnant or breast-feeding women. It should be used with caution by persons with reduced liver function and habitual users of alcohol. The safety and effectiveness of lovastatin for people under the age of 20 have not been established. Driving and other risk-related activities should be restricted if dizziness and blurred vision occur while taking this drug.

Common side effects of lovastatin include constipation, diarrhea, dizziness, gas, headache, heartburn, nausea, skin rash, and stomach pain. Less common side effects are blurred vision, fever, muscle aches or cramps, severe stomach pain, and unusual tiredness or weakness. Long-term use of this drug may result in abnormal liver function tests.

Lovastatin may interact adversely with certain drugs including clofibrate, cyclosporine, erythromycin and other macrolide antibiotics such as asithromycin and clarithromycin, gemfibrozil, niacin, and warfarin.

Brand Name:Mevacor

Coronary Heart Disease

Coronary heart disease, the most common type of heart disease caused by atherosclerosis, the buildup of fatty material called plaque on the inside of the coronary arteries (see Arteriosclerosis). Over the course of many years, this plaque narrows the arteries so that less blood can flow through them and less oxygen reaches the heart muscle.

The most common symptom of coronary heart disease is angina pectoris, a squeezing chest pain that may radiate to the neck, jaw, back, and left arm. Angina pectoris is a signal that blood flow to the heart muscle falls short when extra work is required from the heart muscle. An attack of angina is typically triggered by exercise or other physical exertion, or by strong emotions. Coronary heart disease can also lead to a heart attack, which usually develops when a blood clot forms at the site of a plaque and severely reduces or completely stops the flow of blood to a part of the heart. In a heart attack, also known as myocardial infarction, part of the heart muscle dies because it is deprived of oxygen. This oxygen deprivation also causes the crushing chest pain characteristic of a heart attack. Other symptoms of a heart attack include nausea, vomiting, and profuse sweating.

One of the primary risk factors for coronary heart disease is the presence of a high level of a fatty substance called cholesterol in the bloodstream. High blood cholesterol is typically the result of a diet that is high in cholesterol and saturated fat, although some genetic disorders also cause the problem. Other risk factors include smoking, high blood pressure, diabetes mellitus, obesity, and a sedentary lifestyle.

Coronary heart disease cannot be cured, but it can often be controlled with a combination of lifestyle changes and medications. Patients with coronary heart disease are encouraged to quit smoking, exercise regularly, and eat a low-fat diet. Doctors may prescribe a drug such as lovastatin, simvastatin, or pravastatin to help lower blood cholesterol. A wide variety of medications can help relieve angina, including nitroglycerin, beta blockers, and calcium channel blockers. Doctors may recommend that some patients take a daily dose of aspirin, which helps prevent heart attacks by interfering with platelets, tiny blood cells that play a critical role in blood clotting.

Gingivitis

Gingivitis, painless inflammation or degeneration of the gum tissue, or gingiva, considered the first stage of gum disease. The gum tissue between the teeth becomes swollen and uneven; the tissue at the gum line becomes darker; and gums bleed easily. In advanced cases, the mouth will develop a noticeably unpleasant odor.

Gingivitis is caused by the buildup of plaque, a film of bacteria that sticks to the teeth at the gum line. Toxins released from the bacteria irritate the gums, causing the gums to swell and bleed. This enables the bacteria to penetrate just below the gum line into an area known as the gingival sulcus. Warm, moist, and protected from the tongue and the chewing movement of the teeth, the gingival sulcus provides the perfect environment for bacteria to breed. Moreover, the delicate tissues of the sulcus are particularly vulnerable to the strong toxins produced by the bacteria. As the bacteria grow and continue to release toxins, they create a solid pocket of plaque beneath the gum line. This bacteria-filled pocket causes the gums to become more inflamed, which weakens the tissue, allowing even more plaque to be trapped in the expanding pocket.

Left untreated, gingivitis progresses to the next stage of gum disease known as periodontitis. In periodontitis, the inflammation from plaque not only damages the gums but also destroys the bones and ligaments that support the teeth. Eventually, the gums detach from the teeth and the teeth may begin to fall out.

The first step in treating gingivitis is scaling—a thorough professional cleaning of the teeth to remove any plaque. This is particularly important because plaque can harden into a mineral form called calculus or tartar, which can be removed only by professional instruments. In addition, dental structures that can interfere with plaque removal, such as broken fillings or bridges, may be fixed during regular dental cleanings. Most important, the patient will be instructed in proper home care, including regular brushing and effective flossing.

Spasm

Spasm, involuntary and abnormal violent contraction of muscles or muscle tissue. Tonic spasm, or cramp, is characterized by an unusually prolonged and strong muscular contraction, with relaxation taking place slowly. The extreme example of tonic spasm is tetanus, in which the spasms are so violent and so enduring that they may paralyze breathing. In the other form of spasm, called clonic spasm, contractions of the affected muscles take place repeatedly, forcibly, and in quick succession, with equally sudden and frequent relaxations. The most typical examples of clonic spasm are epilepsy and convulsive hysteria.

The medicines used to counteract spasmodic muscular activity are termed antispasmodics. These are used in certain surgical procedures because they block transmission of nervous impulses to the muscles. Derivatives of hemlock and some 50 other plants have a relaxing effect on muscles.

Emphysema

Emphysema, progressive respiratory disease characterized by coughing, shortness of breath, and wheezing, developing into extreme difficulty in breathing, and sometimes resulting in disability and death. Although the exact cause is unknown, bronchial spasm, infection, irritation, or a combination of the three seem to be contributory. The highest degree of occurrence is among heavy cigarette smokers, especially those exposed to polluted air. Children who suffer from bronchitis or asthma are also susceptible.

In the course of the disease the passages leading to the air sacs of the lungs become narrowed. Air is trapped in the sacs, and the tissues of the lungs lose their natural elasticity and undergo destructive changes. Symptoms akin to the common cold or asthmatic wheezing may result. As the disease progresses the volume of residual air trapped in the lungs increases, and the volume of each breath decreases. The lungs increase in size, and in severe cases the patient develops a characteristic “barrel chest.” The lungs become unable to supply enough oxygen to the body tissues. This reduction in oxygen intake causes the heart to pump faster; consequently, the heart becomes strained. Excessive carbon dioxide in the blood gives the patient a bluish skin color.

Elephantiasis

Elephantiasis, disease of the lymphatic system, characterized by an enormous enlargement of the infected area. The hardened skin of this area resembles the hide of an elephant. The disease is usually the result of blockage of the lymphatic system by threadlike filarial worms, usually Wuchereria bancrofti. The parts of the body most frequently affected are the limbs and the genitals. The disease is treated with the antifilarial drug diethylcarbamazine (Hetrazan) and with surgery.

Dysentery

Dysentery, acute or chronic disease of the large intestine of humans, characterized by frequent passage of small, watery stools, often containing blood and mucus, accompanied by severe abdominal cramps. Ulceration of the walls of the intestine may occur. Although many severe cases of diarrhea have been called dysentery, the word properly refers to a disease caused by either a specific amoeba, Entamoeba histolytica, or a bacillus that infects the colon.

Amoebic dysentery, caused by the parasite Entamoeba histolytica, is endemic in many tropical countries, but is attributable more to unsanitary conditions than to heat. It is most commonly spread by water or contaminated, uncooked food or from carriers. Flies may carry the cysts to spread the amoeba from the feces of infected persons to food. Various drugs, including metronidazole, ementine, and iodine-containing preparations, have been useful in treating severe cases of the disease.

Bacillary dysentery is caused by certain nonmotile bacteria of the genus Shigella. This dysentery is usually self-limiting and rarely manifests the more severe organ involvements characteristic of amoebic dysentery. Bacillary dysentery is spread by contaminated water, milk, and food. Feces from active cases and those from healthy carriers as well contain immense numbers of the disease-producing bacteria. Flies carry the bacteria on their feet or in their saliva and feces and deposit them on food; ants are also believed to spread the disease. Proper replacement of fluid is important in treating. Sulfonamides, tetracycline, and streptomycin were effective in curing acute cases until drug-resistant strains emerged. Chloramphenicol is sometimes used to treat these strains. Quinolones such as norfloxacin and ciprofloxacin are also effective against Shigella infection.

Drowning

Drowning, death by suffocation due to the presence of water in the respiratory system.

Resuscitation by artificial respiration can prevent the death of a person with water in the lungs if instituted quickly. Because of the constant need of body tissues for oxygen, even a few minutes of suffocation can result in brain damage or death. The exception to this appears in persons who have been submerged in cold water. Some victims have been completely revived, without brain damage, after having been underwater for as long as a half hour. This phenomenon, the so-called diving reflex, has long been observed in sea mammals. Activated when the face is plunged into water below 21° C (70° F), it slows body processes so that oxygen-bearing blood is diverted to the heart and brain.

Doxycycline

Doxycycline, antibiotic drug used to treat various types of bacterial infections including urinary tract infections, traveler’s diarrhea, Rocky Mountain spotted fever, trachoma, and syphilis. It is also sometimes used to treat early Lyme disease and to prevent the spread of malaria. Doxycycline belongs to a group of antibiotics known as tetracyclines. It works by interfering with the invading bacteria’s ability to form essential proteins, thereby halting their growth.

This drug is available by prescription in capsules, tablets, and liquid forms, which are taken orally, although one form of liquid is made for injection. Typical dosages range from 100 to 200 mg per day, taken in one or two doses, with a recommended maximum dose of 300 mg a day. Unless this drug causes stomach upset, it should be taken on an empty stomach (one hour before or two hours after a meal) with a full glass of water. Doxycycline usually relieves symptoms after 48 hours of treatment, but it should be taken for the entire prescribed length of time to avoid recurrence of infection.

Patients with liver disease and pregnant or breast-feeding women should not use this drug. It may be taken by children over the age of eight at a dosage based on body weight. Possible side effects include diarrhea, nausea, vomiting, skin rash, itching, light sensitivity, headache, facial swelling, chest pain, difficulty swallowing, or bulging forehead (in infants). Children may develop discolored teeth, especially with long-term use.

Doxycyline may interact adversely with antacids and other common gastrointestinal medications, birth control pills, barbiturates, blood-thinners, penicillin, phenytoin, sodium bicarbonate, and carbamazepine.

Brand Names:Doryx, Vibramycin, Vibra-Tabs, Bio-Tab

Psychoactive Drugs

Psychoactive Drugs, chemical substances that alter mood, behavior, perception, or mental functioning. Throughout history, many cultures have found ways to alter consciousness through the ingestion of substances. In current professional practice, psychoactive substances known as psychotropic drugs have been developed to treat patients with severe mental illness.

Psychoactive substances exert their effects by modifying biochemical or physiological processes in the brain. The message system of nerve cells, or neurons, relies on both electrical and chemical transmission. Neurons rarely touch each other; the microscopic gap between one neuron and the next, called the synapse, is bridged by chemicals called neuroregulators, or neurotransmitters. Psychoactive drugs act by altering neurotransmitter function. The drugs can be divided into six major pharmacological classes based on their desired behavioral or psychological effect: alcohol, sedative-hypnotics, narcotic analgesics, stimulant-euphoriants, hallucinogens, and psychotropic agents.

Lysergic Acid Diethylamide

Lysergic Acid Diethylamide (LSD), potent hallucinogenic drug, also called a psychedelic (see Psychoactive Drugs), first synthesized from lysergic acid in Switzerland in 1938. Lysergic acid is a component of the mold of ergot, a fungus that forms on rye grain. The drug evokes dreamlike changes in mood and thought and alters the perception of time and space. It can also create a feeling of lack of self-control and extreme terror. Physical effects include drowsiness, dizziness, dilated pupils, numbness and tingling, weakness, tremors, and nausea.

Transient abnormal thinking induced by LSD, such as a sense of omnipotence or a state of acute paranoia, can result in dangerous behavior. Long-term adverse reactions such as persistent psychosis, prolonged depression, or faulty judgment have also been reported following LSD ingestion, but whether these are a direct result of ingestion is difficult to establish. Physiologically, LSD may cause chromosomal damage to white blood cells; no hard evidence has been found, however, that LSD causes genetic defects in the children of users.

Although LSD is not physiologically addicting, the drug's potent mind-altering effects can lead to chronic use.

The drug has been tried as a treatment for infantile autism, for alcoholism, and to accelerate psychotherapy, but no medical use has been established.