fosamprenavir - oral, Lexiva Glossary of Terms
The following are health and medical definitions of terms that appear in the fosamprenavir - oral, Lexiva article.
Allergic reaction: The hypersensitive response of the immune system of an allergic individual to a substance. Arms: An appendage in anatomy and in clinical trials. See: Arm. Artery: A vessel that carries blood high in oxygen content away from the heart to the farthest reaches of the body. Since blood in arteries is usually full of oxygen, the hemoglobin in the red blood cells is oxygenated. The resultant form of hemoglobin (oxyhemoglobin) is what makes arterial blood look bright red. Benzodiazepines: A class of drugs that act as tranquilizers and are commonly used in the treatment of anxiety. Benzodiazepines can cause drowsiness. Birth control: Birth control is the use of any practices, methods, or devices to prevent pregnancy from occurring in a sexually active woman. Also referred to as family planning, pregnancy prevention, fertility control, or contraception; birth control methods are designed either to prevent fertilization of an egg or implantation of a fertilized egg in the uterus. Blood in the urine: Blood that appears in the urine. Also known as hematuria. Gross hematuria refers to blood that is so plentiful in the urine that the blood is visible with just the naked eye. Microhematuria refers to blood in urine that is visible only under a microscope; there is so little blood that it cannot be seen without magnification. Hematuria, whether gross or microscopic, is abnormal and should be further investigated. It may or may not be accompanied by pain. Painful hematuria can be caused by a number of disorders, including infections and stones in the urinary tract. Painless hematuria can also be due to a large number of causes, including cancer. 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. It's measurement 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 sugar: Blood glucose. See also: High blood sugar; Low blood sugar. Breast milk: Milk from the breast. Human milk contains a balance of nutrients that closely matches infant requirements for brain development, growth and a healthy immune system. Human milk also contains immunologic agents and other compounds that act against viruses, bacteria, and parasites. Since an infant's immune system is not fully developed until age 2, human milk provides a distinct advantage over formula. Breathing: The process of respiration, during which air is inhaled into the lungs through the mouth or nose due to muscle contraction and then exhaled due to muscle relaxation. Cancer: An abnormal growth of cells which tend to proliferate in an uncontrolled way and, in some cases, to metastasize (spread). Chills: feelings of coldness accompanied by shivering. Chills may develop after exposure to a cold environment or may accompany a fever. Cholesterol: The most common type of steroid in the body. Cholesterol has a reputation for being associated with an increased risk for heart and blood vessel disease. However, cholesterol is essential to the formation of bile acids, vitamin D, progesterone, estrogens (estradiol, estrone, estriol), androgens (androsterone, testosterone), mineralocorticoid hormones (aldosterone, corticosterone), and glucocorticoid hormones (cortisol). Cholesterol is also necessary to the normal permeability and function of the membranes that surround cells. A diet high in saturated fats tends to increase blood cholesterol levels, whereas a diet high in unsaturated fats tends to lower blood cholesterol levels. Although some cholesterol is obtained from the diet, most cholesterol is made in the liver and other tissues. The treatment of elevated cholesterol involves not only diet but also weight loss, regular exercise, and medications. After the age of 20, cholesterol testing is recommended every 5 years. Coronary artery disease: Impedance or blockage of one or more arteries that supply blood to the heart, usually due to atherosclerosis (hardening of the arteries). Abbreviated CAD. A major cause of illness and death, CAD begins when hard cholesterol substances (plaques) are deposited within a coronary artery. The plaques in the coronary arteries can lead to the formation of tiny clots that can obstruct the flow of blood to the heart muscle, producing symptoms and signs of CAD, including chest pain (angina pectoris), heart attack (myocardial infarction), and sudden death. Treatment for CAD includes bypass surgery, balloon angioplasty, and the use of stents. Cough: A rapid expulsion of air from the lungs, typically in order to clear the lung airways of fluids, mucus, or other material. Also known as tussis. 
Cure: 1. To heal, to make well, to restore to good health. 2. A time without recurrence of a disease so that the risk of recurrence is small. Diabetes: Refers to diabetes mellitus or, less often, to diabetes insipidus. Diabetes mellitus and diabetes insipidus share the name "diabetes" because they are both conditions characterized by excessive urination (polyuria). Diarrhea: A common condition that involves unusually frequent and liquid bowel movements. The opposite of constipation. There are many infectious and noninfectious causes of diarrhea. Persistent diarrhea is both uncomfortable and dangerous to the health because it can indicate an underlying infection and may mean that the body is not able to absorb some nutrients due to a problem in the bowels. Treatment includes drinking plenty of fluids to prevent dehydration and taking over-the-counter remedies. People with diarrhea that persists for more than a couple days, particularly small children or elderly people, should seek medical attention. Dizziness: Painless head discomfort with many possible causes including disturbances of vision, the brain, balance (vestibular) system of the inner ear, and gastrointestinal system. Dizziness is a medically indistinct term which laypersons use to describe a variety of conditions ranging from lightheadedness, unsteadiness to vertigo. Drain: A device for removing fluid from a cavity or wound. A drain is typically a tube or wick. As a verb, to allow fluid to be released from a confined area. Dysfunction: Difficult function or abnormal function. Erectile dysfunction: A consistent inability to sustain an erection sufficient for sexual intercourse. Commonly known as impotence. Medically, the term erectile dysfunction is used to properly differentiate this form of impotence from other problems that interfere with sexual intercourse, such as disease, injury, drug side effects, or a disorder that impairs the nerve supply or the blood flow to the penis. Other forms of impotence include lack of sexual desire and problems with ejaculation and orgasm. Erectile dysfunction is treatable in all age groups, and treatment includes using medication (notably Viagra) and penile implants. Abbreviated ED. Ergot: A fungus (Claviceps purpurea) that contaminates rye and wheat and that produces substances (alkaloids) called ergotamines. Ergotamines constrict blood vessels and cause the muscle of the uterus to contract. They have been much used for the treatment of migraines. They have also been used and misused to induce abortion. In excess, ergotamines can cause symptoms such as hallucinations, severe gastrointestinal upset, a type of dry gangrene, and a painful burning sensation in the limbs and extremities. Chronic ergot poisoning (ergotism) was rife during the Middle Ages due to the consumption of contaminated rye. Because of the burning pain, it was known as ignis sacer (holy fire) and ignis infernalis (hell's fire), and was one of the causes of St. Anthony's fire. A form of ergot was also the original basis for the illicit drug lysergic acid diethylamide (LSD). Fats: Plural of the word "fat". See the definition of fat. FDA: Food and Drug Administration. Fever: Although a fever technically is any body temperature above the normal of 98.6 degrees F. (37 degrees C.), in practice a person is usually not considered to have a significant fever until the temperature is above 100.4 degrees F (38 degrees C.). Flush: (1) A redness of the skin, typically over the cheeks or neck. A flush is usually temporary and brought on by excitement, exercise, fever, or embarrassment. Flushing is an involuntary (uncontrollable) response of the nervous system leading to widening of the capillaries of the involved skin. Also referred to as a blush (or, as a verb, to blush). Flushing may also be caused by medications or other substances that cause widening of the capillaries, such as niacin. (2) Flush also means to wash out a wound or body area. Generic: 1. The chemical name of a drug. 2. A term referring to the chemical makeup of a drug rather than to the advertised brand name under which the drug may be sold. 3.A term referring to any drug marketed under its chemical name without advertising. Goiter: A noncancerous enlargement of the thyroid gland. With a goiter, the levels of thyroid hormones may be normal (euthyroid), elevated (hyperthyroidism), or decreased (hypothyroidism). Guillain-Barré syndrome: A disorder characterized by progressive symmetrical paralysis and loss of reflexes, usually beginning in the legs. The paralysis characteristically involves more than one limb (most commonly the legs), is progressive, and is usually proceeds from the end of an extremity toward the torso. Areflexia (loss of reflexes) or hyporeflexia (diminution of reflexes) may occur in the legs and arms. Headache: A pain in the head with the pain being above the eyes or the ears, behind the head (occipital), or in the back of the upper neck. Headache, like chest pain or back ache, has many causes. Heart: The muscle that pumps blood received from veins into arteries throughout the body. The heart is positioned in the chest behind the sternum (breastbone); in front of the trachea, esophagus, and aorta; and above the diaphragm. A normal heart is about the size of a closed fist and weighs about 298 grams or 10.5 ounces. It is cone-shaped, with the point of the cone pointing down to the left. Two-thirds of the heart lies in the left side of the chest, with the balance in the right side of the chest. The heart is composed of specialized cardiac muscle, and it is four-chambered, with a right atrium and ventricle, and an anatomically separate left atrium and ventricle. The blood flows from the systemic veins into the right atrium, thence to the right ventricle, from which it is pumped to the lungs and then returned into the left atrium, thence to the left ventricle, from which it is driven into the systemic arteries. The heart is thus functionally composed of two hearts: the right heart and the left heart. The right heart consists of the right atrium, which receives deoxygenated blood from the body, and the right ventricle, which pumps the deoxygenated blood to the lungs under low pressure; and the left heart, which consists of the left atrium, which receives oxygenated blood from the lung, and the left ventricle, which pumps the oxygenated blood out to the body under high pressure. Heart attack: The death of heart muscle due to the loss of blood supply. The loss of blood supply is usually caused by a complete blockage of a coronary artery, one of the arteries that supplies blood to the heart muscle. Death of the heart muscle, in turn, causes chest pain and electrical instability of the heart muscle tissue. Heart disease: Any disorder that affects the heart. Sometimes the term "heart disease" is used narrowly and incorrectly as a synonym for coronary artery disease. Heart disease is synonymous with cardiac disease but not with cardiovascular disease which is any disease of the heart or blood vessels. Among the many types of heart disease, see, for example: Angina; Arrhythmia; Congenital heart disease; Coronary artery disease (CAD); Dilated cardiomyopathy; Heart attack (myocardial infarction); Heart failure; Hypertrophic cardiomyopathy; Mitral regurgitation; Mitral valve prolapse; and Pulmonary stenosis. Hemophilia: An inherited disorder in which the ability of blood to clot normally is impaired. There are two types of hemophilia: hemophilia A and hemophilia B. Hepatitis: Inflammation of the liver, irrespective of the cause. Hepatitis is caused by a number of conditions, including drug toxicity, immune diseases, and viruses. Hepatitis B: Inflammation of the liver due to the hepatitis B virus (HBV), once thought to be passed only through blood products. It is now known that hepatitis B can also be transmitted via needle sticks, body piercing and tattooing using un sterilized instruments, the dialysis process, sexual and even less intimate close contact, and childbirth. Symptoms include fatigue, jaundice, nausea, vomiting, dark urine, light stools. Diagnosis is by blood test. Treatment is via anti-viral drugs and/or hepatitis B immunoglobulin (HBIG). Herbal: 1. An adjective, referring to herbs, as in an herbal tea. High blood pressure: A repeatedly elevated blood pressure exceeding 140 over 90 mmHg. Chronic high blood pressure can stealthily cause blood vessel changes in the back of the eye (retina), abnormal thickening of the heart muscle, kidney failure, and brain damage. No specific cause for high blood pressure is found in 95 percent of patients. Treatment for high blood pressure involves dietary changes, regular aerobic exercise, and medication. There are many types of medications used to treat high blood pressure including diuretics, beta-blockers, blood vessel dilators, and others. Also known as hypertension. HIV: Acronym for the Human Immunodeficiency Virus, the cause of AIDS (acquired immunodeficiency syndrome). HIV has also been called the human lymphotropic virus type III, the lymphadenopathy-associated virus and the lymphadenopathy virus. No matter what name is applied, it is a retrovirus. (A retrovirus has an RNA genome and a reverse transcriptase enzyme. Using the reverse transcriptase, the virus uses its RNA as a template for making complementary DNA which can integrate into the DNA of the host organism). Hypertension: High blood pressure, defined as a repeatedly elevated blood pressure exceeding 140 over 90 mmHg -- a systolic pressure above 140 with a diastolic pressure above 90. Immune: Protected against infection, usually by the presence of antibodies. Infection: The invasion and multiplication of microorganisms such as bacteria, viruses, and parasites that are not normally present within the body. An infection may cause no symptoms and be subclinical, or it may cause symptoms and be clinically apparent. An infection may remain localized, or it may spread through the blood or lymphatic vessels to become systemic (bodywide). Microorganisms that live naturally in the body are not considered infections. For example, bacteria that normally live within the mouth and intestine are not infections. Itching: An uncomfortable sensation in the skin that feels as if something is crawling on the skin and makes the person want to scratch the affected area. Itching is medically known as pruritis; something that is itchy is pruritic. Joint: The area where two bones are attached for the purpose of permitting body parts to move. A joint is usually formed of fibrous connective tissue and cartilage. Joints are grouped according to their type of motion: ball-and-socket joint; hinge joint; condyloid joint, which permits all forms of angular movement except axial rotation; pivot joint; gliding joint; or saddle joint. Joints can move in only four ways: gliding, in which one bony surface glides on another, without angular or rotatory movement; angular, a movement that occurs only between long bones, increasing or decreasing the angle between the bones; circumduction, which occurs in joints composed of the head of a bone and an articular cavity, with the long bone describing a series of circles and the whole forming a cone; and rotation, in which a bone moves about a central axis without moving from this axis. Also known as articulation and arthrosis.
Kidney: One of a pair of organs located in the right and left side of the abdomen. The kidneys remove waste products from the blood and produce urine. As blood flows through the kidneys, the kidneys filter waste products, chemicals, and unneeded water from the blood. Urine collects in the middle of each kidney, in an area called the renal pelvis. It then drains from the kidney through a long tube, the ureter, to the bladder, where it is stored until elimination. The kidneys also make substances that help control blood pressure and regulate the formation of red blood cells. Kidney stone: A stone in the kidney or a stone that originates in the kidney but has passed lower down in the urinary tract. Kidney stones are a common cause of blood in the urine and pain in the abdomen, flank, or groin. The development of kidney stones is related to decreased urine volume or to increased excretion of stone-forming components, such as calcium, oxalate, urate, cystine, xanthine, and phosphate. The stones form in the urine-collecting area (pelvis) of the kidney and may range in size from tiny to 'staghorn' stones the size of the renal pelvis itself. Factors that predispose people to kidney stones include reduction in fluid intake, increased exercise with dehydration, medications that cause high uric acid (hyperuricemia), and a history of gout. Pain from kidney stones is usually of sudden onset, very severe and intermittent, and not improved by changes in position, and it radiates from the back, down the flank, and into the groin. Nausea and vomiting are common. The majority of stones pass spontaneously within 48 hours. However, some stones do not. Several factors influence the ability to pass a stone, including the size of the person, prior stone passage, prostate enlargement, pregnancy, and the size of the stone. If a stone does not pass, the help of a urology specialist may be needed. Routine treatment includes relief of pain, hydration, and, if there is concurrent urinary infection, administration of antibiotics. Also known as nephrolithiasis. Laboratory: A place for doing tests and research procedures, and for preparing chemicals and some medications. Also known as lab. Liver: The largest solid organ in the body, situated in the upper part of the abdomen on the right side. The liver has a multitude of important and complex functions, including to manufacture proteins, including albumin (to help maintain the volume of blood) and blood clotting factors; to synthesize, store, and process fats, including fatty acids (used for energy) and cholesterol; to metabolize and store carbohydrates (used as the source for the sugar in blood); to form and secrete bile that contains bile acids to aid in the intestinal absorption of fats and the fat-soluble vitamins A, D, E, and K; to eliminate, by metabolizing or secreting, the potentially harmful biochemical products produced by the body, such as bilirubin, from the breakdown of old red blood cells and ammonia from the breakdown of proteins; and to detoxify, by metabolizing and/or secreting, drugs, alcohol, and environmental toxins. Medical history: 1. In clinical medicine, the patient's past and present which may contain relevant information bearing on their health past, present, and future. The medical history, being an account of all medical events and problems a person has experienced is an important tool in the management of the patient. MedicAlert: A nonprofit emergency medical information service, known for its MedicAlert jewelry, particularly the bracelet, and its 24-hour emergency response center. Mouth: 1. The upper opening of the digestive tract, beginning with the lips and containing the teeth, gums, and tongue. Foodstuffs are broken down mechanically in the mouth by chewing and saliva is added as a lubricant. Saliva contains amylase, an enzyme that digests starch. 2. Any opening or aperture in the body. The mouth in both senses of the word is also called the os, the Latin word for an opening, or mouth. The o in os is pronounced as in hope. The genitive form of os is oris from which comes the word oral. Muscle: Muscle is the tissue of the body which primarily functions as a source of power. There are three types of muscle in the body. Muscle which is responsible for moving extremities and external areas of the body is called "skeletal muscle." Heart muscle is called "cardiac muscle." Muscle that is in the walls of arteries and bowel is called "smooth muscle." Nausea: Stomach queasiness, the urge to vomit. Nausea can be brought on by many causes, including systemic illnesses (such as influenza), medications, pain, and inner ear disease. Nerve: A bundle of fibers that uses electrical and chemical signals to transmit sensory and motor information from one body part to another. The fibrous portions of a nerve are covered by a sheath called myelin and/or a membrane called neurilemma. (Note that entries for specific nerves can be found under the names of the particular nerves. For example, the optic nerve is not under 'nerve, optic' but rather under 'optic nerve.') Pain: An unpleasant sensation that can range from mild, localized discomfort to agony. Pain has both physical and emotional components. The physical part of pain results from nerve stimulation. Pain may be contained to a discrete area, as in an injury, or it can be more diffuse, as in disorders like fibromyalgia. Pain is mediated by specific nerve fibers that carry the pain impulses to the brain where their conscious appreciation may be modified by many factors. Painful urination: See: Dysuria. Paralysis: Loss of voluntary movement (motor function). Paralysis that affects only one muscle or limb is partial paralysis, also known as palsy; paralysis of all muscles is total paralysis, as may occur in cases of botulism. Pharmacist: A professional who fills prescriptions and, in the case of a compounding pharmacist, makes them. Pharmacists are very familiar with medication ingredients, interactions, and cautions. Poison: Any substance that can cause severe organ damage or death if ingested, breathed in, or absorbed through the skin. Many substances that normally cause no problems, including water and most vitamins, can be poisonous if taken in excessive quantity. Poison treatment depends on the 'substance.
Poison control center: A special information center set up to inform people about how to respond to potential poisoning. These centers maintain databases of poisons and appropriate emergency treatment. Local poison control centers should be listed with other community-service numbers in the front of the telephone book, and they can also be reached immediately through any telephone operator. Pregnancy: The state of carrying a developing embryo or fetus within the female body. This condition can be indicated by positive results on an over-the-counter urine test, and confirmed through a blood test, ultrasound, detection of fetal heartbeat, or an X-ray. Pregnancy lasts for about nine months, measured from the date of the woman's last menstrual period (LMP). It is conventionally divided into three trimesters, each roughly three months long. Pregnant: The state of carrying a developing fetus within the body. Prescription: A physician's order for the preparation and administration of a drug or device for a patient. A prescription has several parts. They include the superscription or heading with the symbol "R" or "Rx", which stands for the word recipe (meaning, in Latin, to take); the inscription, which contains the names and quantities of the ingredients; the subscription or directions for compounding the drug; and the signature which is often preceded by the sign "s" standing for signa (Latin for mark), giving the directions to be marked on the container. Protease: An enzyme that can split a protein into the peptides from which it was originally created. Protease inhibitor: An agent that can keep a protease from splitting a protein into peptides. Examples of protease inhibitors are saquinavir (brand name: Invirase) and ritonavir (brand name: Norvir), and they are used primarily in HIV/AIDS treatment. They are taken as part of a multi-drug cocktail and have been shown to be capable of significantly reducing the level of HIV virus in the blood. Side effects associated with protease inhibitors include lipodystrophy syndrome, in which the face, arms, and legs become thin due to loss of subcutaneous fat; the skin becomes dry; weight loss occurs; and abnormal deposits of fat occur. Some strains of HIV may be resistant to protease inhibitors. Pulmonary: Having to do with the lungs. Pulmonary hypertension: High blood pressure in the pulmonary arteries. This elevated blood pressure can lead to severe shortness of breath and death. Lung transplantation is considered in severe cases that are unresponsive to treatments. Quality of life: The patient's ability to enjoy normal life activities. Quality of life is an important consideration in medical care. Some medical treatments can seriously impair quality of life without providing appreciable benefit, whereas others greatly enhance quality of life. Rash: Breaking out (eruption) of the skin. A rash can be caused by an underlying medical condition, hormonal cycles, allergies, or contact with irritating substances. Treatment depends on the underlying cause of the rash. Medically, a rash is referred to as an exanthem. Shortness of breath: Difficulty in breathing. Medically referred to as dyspnea. Shortness of breath can be caused by respiratory (breathing passages and lungs) or circulatory (heart and blood vessels) conditions and other conditions such as severe anemia or high fever. See also dyspnea. Sore: 1. (adjective) A popular term for painful, such as a sore throat. 2. (noun) A nondescript term for nearly any lesion of the skin or mucous membranes. He has a number of sores in his mouth. Sore throat: Pain in the throat. Sore throat may be caused by many different causes, including inflammation of the larynx, pharynx, or tonsils. Stomach: The digestive organ that is located in the upper abdomen, under the ribs. The upper part of the stomach connects to the esophagus, and the lower part leads into the small intestine. When food enters the stomach, muscles in the stomach wall create a rippling motion (peristalsis) that mixes and mashes the food. At the same time, juices made by glands in the lining of the stomach help digest the food. After about 3 hours, the food becomes a liquid and moves into the small intestine, where digestion continues. Surgery: The branch of medicine that employs operations in the treatment of disease or injury. Surgery can involve cutting, abrading, suturing, or otherwise physically changing body tissues and organs.
Sweating: The act of secreting fluid from the skin by the sweat (sudoriferous) glands. These are small tubular glands situated within and under the skin (in the subcutaneous tissue). They discharge by tiny openings in the surface of the skin. Syndrome: A combination of symptoms and signs that together represent a disease process. Taste: A perception that results from stimulation of a gustatory nerve. Taste belongs to the chemical sensing system. Tasting begins when molecules stimulate special cells in the mouth or throat. These special cells transmit messages through nerves to the brain, where specific tastes are identified. Gustatory, or taste, cells react to food and beverages. The taste cells are clustered in the taste buds of the mouth and throat. Many of the small bumps that can be seen on the tongue contain taste buds. Smell contributes to the sense of taste, as does another chemosensory mechanism, called the common chemical sense. In this system, thousands of nerve endings'especially on the moist surfaces of the eyes, nose, mouth, and throat'give rise to sensations such as the sting of ammonia, the coolness of menthol, and the irritation of chili peppers. People can commonly identify four basic taste sensations: sweet, sour, bitter, and salty. In the mouth, these tastes, along with texture, temperature, and the sensations from the common chemical sense, combine with odors to produce the perception of flavor. Flavors are recognized mainly through the sense of smell. If a person holds his or her nose while eating chocolate, for example, the person will have trouble identifying the chocolate flavor'even though he or she can distinguish the food's sweetness or bitterness. That is because the familiar flavor of chocolate is sensed largely by odor. Throat: The throat is the anterior (front) portion of the neck beginning at the back of the mouth, consisting anatomically of the pharynx and larynx. The throat contains the trachea and a portion of the esophagus. Thyroid: 1. The thyroid gland. Also, pertaining to the thyroid gland. 2. A preparation of the thyroid gland used to treat hypothyroidism. 3. Shaped like a shield. (The thyroid gland was so-named by Thomas Wharton in 1656 because it was shaped like an ancient Greek shield.) Tiredness: See: Tired. Triglycerides: The major form of fat stored by the body. A triglyceride consists of three molecules of fatty acid combined with a molecule of the alcohol glycerol. Triglycerides serve as the backbone of many types of lipids (fats). Triglycerides come from the food we eat as well as from being produced by the body. Urine: Liquid waste produced by the kidneys. Urine is a clear, transparent fluid that normally has an amber color. The average amount of urine excreted in 24 hours is between 5 to 8 cups or 40 and 60 ounces. Chemically, urine is mainly a watery solution of salt and substances called urea and uric acid. Normally, it contains about 960 parts water to 40 parts solid matter. Abnormally, it may contain sugar (in diabetes), albumin (a protein, as in some forms of kidney disease), bile pigments (as in jaundice), or abnormal quantities of one or another of its normal components. Viral: Of or pertaining to a virus. For example, if a person has a viral rash, the rash was caused by a virus. Virus: A microorganism that is smaller than a bacterium that cannot grow or reproduce apart from a living cell. A virus invades living cells and uses their chemical machinery to keep itself alive and to replicate itself. It may reproduce with fidelity or with errors (mutations); this ability to mutate is responsible for the ability of some viruses to change slightly in each infected person, making treatment difficult. Viruses cause many common human infections and are also responsible for a number of rare diseases. Examples of viral illnesses range from the common cold, which can be caused by one of the rhinoviruses, to AIDS, which is caused by HIV. Viruses may contain either DNA or RNA as their genetic material. Herpes simplex virus and the hepatitis B virus are DNA viruses. RNA viruses have an enzyme called reverse transcriptase that permits the usual sequence of DNA-to-RNA to be reversed so that the virus can make a DNA version of itself. Weight loss: Weight loss is a decrease in body weight resulting from either voluntary (diet, exercise) or involuntary (illness) circumstances. Most instances of weight loss arise due to the loss of body fat, but in cases of extreme or severe weight loss, protein and other substances in the body can also be depleted. Examples of involuntary weight loss include the weight loss associated with cancer, malabsorption (such as from chronic diarrheal illnesses ), and chronic inflammation (such as with rheumatoid arthritis).
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