Glossary: Common Words & Terms

Adherence: Taking medication at the right dose / time and in the right way to ensure it's effectiveness.

AIDS: Acquired Immune Deficiency Syndrome. Specific illnesses and infections which occur because the immune system has been damaged by HIV.

Anaemia: A condition that occurs if the blood cannot carry enough oxygen to nourish tissues. Common symptoms of anaemia are fatigue, headache, and shortness of breath. Too few red blood cells or too little haemoglobin or both may cause anaemia.

Antibody: A protein substance in the blood which recognises and blocks foreign substances.

Antigen: A substance which, when introduced into the body, is capable of starting the production of a specific antibody by the immune system.

Anti-retroviral: A drug that acts against retroviruses such as HIV. (Zalcitabine (ddC) and Nevirapine (Viramune) are examples of anti-retroviral drugs).

Antiviral: A drug that works against viruses.

Asymptomatic: Without symptoms. Someone who is asymptomatic has anti-bodies to HIV but does not have any visible signs or symptoms of HIV infection.

Bioavailability: The rate and extent to which a drug is available for action in the body.

Biopsy: Removal of tissue from the living body. A biopsy is usually done to clearly determine the cause of an illness.

Buffered: Coated with a special substance that allows easier absorption by the stomach. Buffered drugs often prevent stomach upset. They may also help to avoid damage by stomach acids.

CD4: A protein embedded in the outside of immune system cells called helper T-lymphocytes, or T cells. The protein allows scientists to identify helper T cells, also called T4 cells. The protein is also used by HIV to infect these cells. The number of T4 cells in a blood sample is used to measure the health of the immune system in people with HIV.

CD8: A molecule on the surface of some white blood cells. Some of these cells can kill other cells that are
infected with foreign organisms.

Clinical trial: A research study with people, usually to find out how well a new drug or treatment works in people and how safe it is.

CMV: Cytomegalovirus. A member of the herpes family of viruses. In HIV disease CMV may affect the eyes (retinitis) the gut (oesophagitis or colitis) and occasionally the lungs, liver or nervous system.

CNS: Central nervous system: The main part of the nervous system including the brain and spinal cord.

Combination therapy: The use of two or more drugs as treatment.

Cytokines: Proteins produced by white blood cells that act as chemical messengers between cells. Examples of cytokines are tumour necrosis factor (TNF), alpha-interferon, and interleukin-2.

Cytotoxic: Term used to describe something that damages cells. Also used as the name of a type of T-cell.

Dementia: The Loss of memory and other intellectual functioning caused by HIV or another disease.

DNA: The material in the nucleus of a cell where genetic information is stored.

Double-blind: A type of drug trial in which people are divided into different groups. One group takes the experimental drug and other groups take different doses, the standard therapy, or placebo. Neither the researchers nor the person in the trial knows who is taking what until the trial is over.

Enzyme: Protein chemical that accelerates chemical reactions in the body.

Expanded access: Programs designed to make experimental drugs available on a wide basis to people who do not qualify for a drug on trial.

HAART: Highly Active Anti-retroviral Therapy: a phrase sometimes to used to describe HIV combination therapy with three or more drugs.

Haemoglobin: The protein in red-blood cells responsible for carrying oxygen.

HIV disease: A term used to describe a variety of symptoms and signs found in people who are HIV positive. These may include recurrent fevers, unexplained weight loss, swollen lymph nodes, skin rashes, and/or fungus infection of the mouth and throat. Also commonly described as symptomatic HIV infection.

Hypersensitivity: An allergic reaction to drugs or other substances.

Immune system: The body's mechanisms for fighting infections and tumour cells.

Immunosuppression: A reduction in the ability of the immune system to fight infections.

Inhibitor: In medicine, this refers to a drug or chemical or substance that inhibits or blocks something from happening, such as Protease Inhibitor.

Interaction: Change in the body's response to one drug when another is taken. Interaction may increase the effect of one or both drugs, decrease the effect of one or both drugs, or cause toxicity.

Intravenous: Injected into a vein.

Lactic acidosis: A rare side effect of nucleoside analogue drugs which causes a high level of lactic acid in the body.

Leukocytes: All white blood cells.

Leukopenia: A lower than normal level of leukocytes in the blood.

Lipoatrophy: Loss of body fat from limbs and face.

Lipodystrophy: A disruption in the way the body produces, uses and distributes fat.

Lymphocyte: A type of white blood cell.

Maintenance therapy: Taking drugs for a period of time after an infection has been treated, to stabilise the condition or prevent a recurrence.

Monotherapy: Taking a drug on its own, as opposed to in combination with other drugs.

Myopathy Muscle wastage due to disease or drug side effect.

Nucleoside: Analogue Also known as nucleoside reverse transcriptase inhibitors. A class of anti-HIV drug, which blocks the action of the enzyme, reverse transcriptase. They include Abacavir, Didanosine, Lamivudine, Stavudine, and Zidovudine.

Neuropathy: Any abnormal, degenerative or inflammatory state of the peripheral nervous system.

Neutropenia: A low number of neutrophils in the blood. Neutrophils are a white blood cell important in defending the body against infections.

Neutrophil: A white blood cell which plays a central role in the immune system. Neutrophils are the immune system's main defence against bacterial infections.

NNRTI: Non-nucleoside reverse transcriptase inhibitor. A class of anti-HIV drug, which blocks the action of the enzyme reverse transcriptase. They include Nevirapine, Delavirdine and Efavirenz.

NRTI: Nucleoside reverse transcriptase inhibitor. See Nucleoside Analogue.

NtRTI: Nucleotide reverse transcriptase inhibitors. A class of drug which works in a similar way to NRTI’s. Only one is currently available in this type - Tenofovir.

O. I.: Opportunistic Infections. Specific infections that cause disease to those with HIV or other immunosuppressed persons.

Peripheral neuropathy: A disorder of the nerves, usually involving the hands, feet, arms and legs. Symptoms may include numbness, a tingling or burning sensation, sharp pain, weakness and abnormal reflexes. In severe cases, paralysis may result. Caused by HIV, Hepatitis C, alcohol and or be a side effect of some drugs. This condition can often be successfully treated.

PCP: PCP is an infection of the lungs caused by the micro-organism Pneumocystis zerofir. It causes disease only in people with weakened immune systems. Sometimes the organism can also affect other parts of the body, such as lymph nodes, bone marrow, spleen, liver and occasionally the eyes.

PML: Progressive Multifocal Leukoencaphalopathy. Rare disease of the central nervous system resulting in the destruction of the protective sheath that covers nerves.

Prophylactic: A drug that helps to prevent a disease before it occurs. For example, Septrin is a prophylactic treatment that prevents PCP and Toxoplasmosis.

Prophylaxis: Taking a drug to prevent yourself from getting an illness.

Protease: A substance in the blood that breaks down proteins. HIV has a protease enzyme that it uses to make more virus.

Protease Inhibitors: Protease inhibitors (or PI's) are used in the treatment of HIV infection in combination with other anti-HIV drugs. Protease is one of HIV's enzymes; its role is to break up the long chains of HIV proteins that are produced inside infected cells. Protease inhibitors prevent protease from cutting the protein chains into the shortest pieces that HIV needs to make new virus particles. By working in this way protease inhibitors reduce the number of new active copies of HIV that can infect other cells. They include Amprenavir, Atazanovir, Indinavir (Crixivan), Lopinavir/r (Kaletra), Nelfinavir (Viracept), Ritonavir (Norvir) and Saquinavir (Invirase & Fortovase).

Resistance: The ability of a disease to overcome a drug. For example, after long- term use of AZT, HIV can develop strains of virus in the body that are no longer suppressed by this particular drug, and therefore are said to be resistant to AZT.

Retinitis: Inflammation of the retina, a part of the eye, which can be caused by cytomegalovirus (CMV) infection. If left untreated, CMV retinitis can lead to blindness.

Retrovirus Retroviruses: are RNA viruses that transcribe their genetic material into DNA using an enzyme called reverse transcriptase.

Reverse transcriptase: An enzyme that is needed by HIV to get inside cells and make more of itself.

Salvage therapy: Treatment for individuals who don't respond to or who can't take standard treatments for a condition.

Symptomatic: Infection with symptoms. Someone who is symptomatic has anti-bodies to HIV and has visible signs or symptoms of HIV infection.

T cells: White blood cells that play an important part in the immune system. There are three different types of T cells, each of which has different subsets. The commonly measured T cells are helper T cells, killer T cells, and suppressor T cells.

Viral load: The amount of measurable virus in a blood sample. Tests used to measure virus are PCR (polymerease chain reaction assay or Amlicor) and bDNA. (branched DNA assay). The result provides information about the risk of disease progression. The test is also used to find out how well an anti-HIV treatment is working.