Definitions.

Adherence: how well someone takes medication as directed, with respect to number and timing of doses.

Antioxidant: certain vitamins and other substances that provide protection from the damage caused by "free radicals," which are created as a result of oxygen reactions in living tissues.

Cataract: a clouding of the lens of the eye resulting in poor vision.

Control group: a special situation in research where no drug is given or no test is done. For example, a control group that gets a sugar pill (or "placebo," see below) might be compared to an experimental group that gets a real medication to see what the effects of the medication are.

CT: a scan showing a sectional view of the body and created by "computed tomography" (CT), also known as "computer-assisted tomography" (CAT).

Diabetes: a disorder involving insulin (a substance in the body that helps regulate blood sugar) that results in too much sugar in the blood and urine. Symptoms include hunger, thirst, weight loss, and frequent urination.

DNA (deoxyribonucleic acid): the genetic material that is found in all living things.

Drug-resistance mutation: a genetic change (mutation) that allows HIV to reproduce itself in the presence of an HIV medication.

Dyslipidemia: abnormal levels of lipid (fat) in the blood.

Glaucoma: an eye disease where increased pressure in the aye causes damage and loss of vision.

Hormone: a substance secreted by one part of the body that stimulates cells in another part of the body (for example, testosterone).

Incontinence: loss of bladder or bowel control.

Insulin resistance: decreased sensitivity to insulin that is associated with diabetes (see above).

Lactic acidosis: a build-up of lactic acid in the body. Lactic acid is a substance in blood and muscle produced by the body when it is processing sugar for energy (usually when exercising or if oxygen levels are low).

Lipodystrophy: changes in body fat such as loss of fat in the arms and legs and accumulation of fat in the gut or at the back of the neck.

Metabolism (metabolic): chemical reactions in the body that are part of life; for example, turning food into energy or breathing in oxygen and breathing out carbon dioxide.

MRI: magnetic resonance imaging, a non-invasive technique that creates a computer-generated image of the body.

Multi-drug resistant HIV: virus that has changed (mutated) genetically so that it is able to reproduce itself in the presence of several HIV medications.

Opportunistic: referring to a disease or infection caused by an organism that is usually harmless, but becomes activated when a person's immune system is impaired or damaged.

Peripheral neuropathy: damage to peripheral nerves (such as those in the arms and legs) resulting in muscle weakness, pain, and numbness.

Placebo: sometimes just the act of taking a pill can make someone feel better; so, to watch for this, a placebo (a pill or substance with no effect, such as a sugar pill) is often used to compare with a real medication to see what the medication's true effects might be. This would typically be used in a control group (see above).

Regimen: a combination or schedule of medications.

Subcutaneous: under or into the skin.

Toxicity: a poisonous or damaging effect on the body.