Viral load test See viral load

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viral suppression Viral suppression is a goal of highly active antiretroviral therapy (HAART), as well as other medical therapy in HIV. Suppression is measured differently for different people. viral load is usually given in virions per milliliter of blood. So a count of 100,000 means 100,000 virions/mL of blood.

Changes in viral load are stated in terms of logarithmic (log) changes. Log is a mathematical term that represents a large number measured by a factor of 10. So if you have a viral load of 100,000 and your viral load change is -1.0 log, then your new viral load would be 10,000. A 1 log increase or decrease equals a tenfold (multiplied 10 times) adjustment, which is another way this change is often expressed. In someone who has an extremely high viral load, above 1,000,000, anything less than 10,000 viral load would be a successful result of therapy.

Many doctors seek a viral load drop of 10 times, or 1.0 log, the first month of therapy. Then they seek to suppress the viral load to below the detectable level of viral load tests within three to six months. This gives CD4 cells time to regroup and produce at a rate that can boost the body's defenses. Some people who have HIV never achieve a viral load below the 400 count that is considered the measurable level. This may mean that they have some drug resistance or are not adhering to the drug schedule. In 90 percent of people who have a drop of viral load an increase in CD4 cells also occurs.

The ultrasensitive viral load assay is more expensive and is not performed unless specifically requested. It measures viral load to less than 50 copies/mL. The standard viral load measurement tests cannot detect viral activity accurately below 400 copies/mL. Therefore, patients are generally told they have less than 400 copies/mL, or below the level of quantification, as their viral load result. If someone says an individual has an unde-tectable viral load, this is not quite correct. The person still has a virus that can be passed to other people, even if the viral load is below the level the test can measure.

viral test Generally, a blood test for HIV activity, and for other markers of disease severity or progression. These tests are critically important for developing new drugs and for patient care. Reliable tests might shorten the time required to show which drugs are good candidates from years to months, allowing many more potential treatments to be tested. Better viral tests could also improve medical care with the drugs we already have by showing when a course of treatment is working for an individual and when it is not, so that the physician will have rational guidance on when to add or switch therapies. Examples of viral tests include pcr (polymerase chain reaction), quantitative PCR, QC-PCR (quantitative competitive PCR), BRANCHED DNA ASSAY (bDNA), P24 ANTIGEN TEST, and viral cultures. See viral assay.

Viramune See nevirapine viremia The presence of a virus in blood or blood plasma. Viremia may be a qualitative as well as a quantitative measure of virus.

virion A complete viral particle existing outside a cell.

virologic failure The failure to achieve the desired degree of viral suppression (less than 50 copies/mL on some tests, less than 400 copies/mL on the most common viral load assays) or a viral rebound in a patient whose viral load had previously not been quantifiable.

virology Study of viRUses and viral diseases.

virucide An agent that destroys or inactivates a

VIRUS.

viruria presence of a virus in the urine as measured by urinalysis done on a sample provided by a patient.

virus Any of a large group of submicroscopic agents, or microbes, capable of infecting plants, animals, and bacteria, characterized by a total dependence on living cells for reproduction and a lack of independent metabolism. unlike bacteria, viruses can neither survive nor reproduce unless they live in a cell. Viruses consist of a core of genetic material, either rna or dna, surrounded by a protein coat. hiv is a virus that lives in CD4 lymphocytes in humans. Viruses may be named and classified according to the host they dominate, or according to their origin, mode of transmission, manifestations, and geographic location where they were first isolated.

virus-hunting Nearly discredited by the failed war on cancer, virus-hunting is the attempt to link viruses and illness. In large part due to AIDS, virus-hunting has enjoyed a spectacular revival in the 1980s and 1990s. Within the context of AIDS, virus-hunting has become a public scientific controversy. on one side stand microbiologist peter Duesberg and a circle of defenders who believe that the human immunodeficiency virus (HIV) has not been proved to cause AIDS. These "dissidents" argue that HIV is an innocent bystander in the AIDS epidemic, and assert that millions of dollars have been poured into research to find vaccines and therapies, and thousands of people are poisoning themselves with toxic medications, all in the goal of obstructing a virus that doesn't make anyone sick. On the other side are mainstream AIDS researchers who insist that HIV is the primary cause of AIDS.

visceral leishmaniasis Leishmaniasis caused by Leishmania donovani.

visna A viral disease that affects sheep. The primary target is the central nervous system. It is characterized by asymptomatic onset and partial paralysis of the hindlimbs, progressing to total paralysis and death.

visualization The act of viewing or sensing a picture of an object.

one of many different methods used to reach a state of relaxation. With eyes closed, one becomes completely relaxed either by another method or, for example, by visualizing walking down a shaded stairway, becoming more and more relaxed as one descends into comforting darkness.

once relaxed, an image is brought to mind that may represent the desired change in any number of ways. Some people see themselves as being completely healthy. others imagine the healing white blood cells as white knights charging forth, conquering the invading infections and visualizing the "bad guys" in full retreat. For those who may have trouble focusing clearly on an image, the suggestion is made to draw the desired image on paper to give it more substance and reality. The practice of visualization or imagery is recognized as one of the most powerful healing techniques available today.

vitamin Any of a group of organic substances other than proteins, carbohydrates, fats, minerals, and organic salts that are essential for normal metabolism, growth, and development of the body. Vitamins are not sources of energy; nor do they contribute significantly to the substance of the body, but they are indispensable for the maintenance of health. Effective in minute quantities, they act principally as regulators of metabolic processes and play a role in energy transformation, usually acting as coenzymes in enzymatic systems. Vitamins may be fat-soluble or water-soluble. Fat-soluble vitamins are processed by the liver. They are generally stored for long periods in the body for use when needed. Water-soluble vitamins are processed in the kidney. They are not stored to a great extent in the body, so frequent consumption is necessary. When present in excess of the body's needs, they are excreted in the urine. See minerals.

vitamin A Vitamin A, also known as retinol, was first isolated in 1913. When its chemical structure was first defined, its discoverer won the Nobel Prize in chemistry because it was the first vitamin isolated and described chemically. Vitamin A is essential for vision, for adequate growth, and for the proper development of cells and body tissues. It is particularly important in the formation of epithelial cells, which are the linings of the body (skin, cornea, and mucous membranes, among others). Deficiencies in vitamin A can cause night blindness, tumors of the eyes, and reductions in levels of white cells and red blood cells. Resistance to infection is impaired. Thus vitamin A deficiency can result in more, and more severe, diseases of many types. Vitamin A deficiency has also been related to the development of a variety of cancers. Several illnesses can cause deficiencies, particularly stomach, intestinal, and liver diseases. This is because vitamin A is fat-soluble and must be absorbed and processed in the liver, where it is stored for future use. Level of vitamin A has been shown to be deficient in many HIV-positive people. Supplementation in HIV-positive people has shown no direct influence on CD4 counts or viral load numbers. However, many practitioners believe vitamin A can act as an adjuvant to a healthy immune system. Beta-carotene is a proform of vitamin A. It is the supplement most often used when adding vitamin A to the diet. Because beta-carotene is also a coloring (yellow-orange), one sign of excess of vitamin A is orange coloring of the skin. An excess of vitamin A can lead to severe health problems; it can cause toxicity quite quickly over the course of a few days of oversupplementation. Beta-carotene has been studied extensively and is thought to help prevent some cancers. It is not automatically stored in the body since it is a prodrug and is excreted when it is not needed. However, it has been linked to lung cancer in people who use tobacco. Smokers should not supplement vitamin A with beta-carotene. Foods rich in beta-carotene include carrots, yellow and dark green leafy vegetables (e.g., spinach, broccoli), pumpkin, apricots, and melon. Retinol is found in liver, egg yolk, fish, whole milk, butter, and cheese.

vitamin B complex A group of water-soluble vitamins isolated from liver, yeast, and other sources. Among the B vitamins are thiamine (vitamin BJ, riboflavin (vitamin B2, niacin (vitamin B3), pyridoxine (vitamin B6), biotin, pantothenic acid (vitamin B5), folic acid (or folate, vitamin B9), and cyanocobalamin (vitamin B12). The vitamin B complex affects growth, appetite, lactation, and the gastrointestinal, nervous, and endocrine systems; aids in marasmus; stimulates appetite; aids metabolism of carbohydrates; and stimulates biliary action. B vitamins are also used as adjuncts to some antituberculosis drugs.

Deficiency disorders include beriberi, pellagra, digestive disturbances, enlargement of the liver, disturbance of the thyroid, degeneration of sex glands, and neurological disturbances. Vitamin B deficiencies induce edema; affect the heart, liver, spleen, and kidneys; enlarge the adrenals; and cause dysfunction of the pituitary and salivary glands. Dietary sources of thiamine include red meat, whole grains, potatoes, peas, beans, nuts, and yeast. As this nutrient is water-soluble, it can be lost when food is cooked in liquids.

Natural sources of riboflavin (B2) include dairy products, meat, fish, and green leafy vegetables. whole grain cereals are also good sources, as are egg whites. Vitamin B2 is broken down by heat, so exposure during cooking (by broiling, for instance) can deplete it. Vitamin B2 is given to alcoholics to reduce delirium tremens (DTs).

Deficiencies in vitamin B6 are common in HIVpositive people. Foods rich in B6 include meat, fish, egg yolks, beans, fruits, and vegetables. Liver is a good source, as are whole grain cereals. Losses occur during cooking. However, an excess of vitamin B6 can lead to neurologic damage. It is given to people who are taking isoniazid for tuberculosis.

Studies have shown 25 percent of HIV-positive people have deficiencies in vitamin B12. It has an important function in nerve and spinal cord health. It is provided in the diet by meat, fish, and eggs, so vegetarians are particularly at risk of deficiency. AZT and d4T cause the creation of large red blood cells, as also occurs in deficiencies of B12. This is called pernicious anemia and causes a lack of oxygen in the blood. However, it has not been shown that these two issues are the same problem.

Folate can be found in leafy vegetables, organ meats, and yeast, which are good dietary sources. Alcohol causes deficiencies of folic acid. It plays an important role in the metabolism of DNA and RNA, the carriers of genetic information in all living things. women should take extra folic acid before and during pregnancy to ensure proper fetal development. The other B vitamin levels are rarely deficient. They are readily available in most B supplements and a variety of food sources.

vitamin C (ascorbic acid) A vitamin necessary for the formation of collagen, the intercellular substance of connective tissue, which is essential to maintenance of the integrity of intercellular cement in many tissues, especially capillary walls. Deficiency leads to scurvy, a disorder of skin and bone that causes capillary bleeding. Except guinea pigs, primates are the only mammals who cannot make it in their bodies. Few nutrients are as active in human metabolism as ascorbic acid. It is known to be the most important water-soluble antioxidant and cofactor in cellular metabolism. Researchers have clearly demonstrated that the immune system is sensitive to intake levels of vitamin C and that numerous immunological functions are dependent on it for their mediation. Vitamin C is possibly the most often used dietary supplement, particularly by immune-suppressed individuals and those suffering from other degenerative illnesses. Vitamin C can be purchased in tablet, capsule, or powdered form. If vitamin C powder is taken dissolved in water or juice, it should be drunk with a straw, as ascorbic acid can, over time, erode tooth enamel. The major side effects of an excess of vitamin C, and that in extremely high doses, are diarrhea and oxalate kidney stones.

vitamin D A generic name for a group of steroidlike substances with antirachitic (curing rickets) activity, vitamin D is essential in calcium and phosphorus metabolism and supports healthy bone growth. It also plays an important role in the proper functioning of muscles, nerves, blood clotting, cell growth, and energy utilization. Deficiency disorders include imperfect skeletal formation, bone diseases, rickets, and caries (erosion of teeth). Vitamin D is most readily received from milk products and sunlight. Excessive consumption of vitamin D can cause calcium levels in the blood that reach toxic, life-threatening levels.

vitamin E A fat-soluble vitamin, composed of a group of compounds called tocopherols. Seven forms of tocopherol exist in nature: alpha, beta, delta, epsilon, eta, gamma, and zeta. of these, alpha-tocopherol is the most potent form and has the greatest nutritional and biological value. Toco-pherols occur in highest concentrations in cold-pressed vegetable oils, seeds and nuts, and soybeans. wheat germ oil is the source from which vitamin E was first obtained. The vitamin is necessary for all oxygen-consuming life forms. Vitamin E

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