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HIV/AIDS Dictionary
Acute Infection: The time period just after a person is first infected with HIV but before their body mounts an antibody response that is detectable by conventional HIV tests. Frequently accompanied by “flu-like ” symptoms such as fever, rash, headache, swollen glands in your, joint and muscle aches, and fatigue. Also called primary infection. See HIV Basics section Symptoms of HIV for a description of the early infection period and symptoms.
Adverse Reaction: (Adverse Event.) An unwanted effect caused by the administration of medications or vaccine. Onset may be sudden or develop over time (See Side Effects).
Advocacy and Support Groups: Organizations and groups that actively support participants and their families with valuable resources, including self-empowerment and survival tools.
Antibody: An infection-fighting protein molecule in blood or body fluid that attaches to, neutralizes, and helps destroy bacteria, viruses or other harmful toxins (antigen). Antibodies, known generally as immunoglobulins, are made by white blood cells in response to a foreign substance. Each specific antibody binds only to the specific antigen that stimulated its production. (See also immunoglobulin; binding antibody; enhancing antibody; functional antibody; neutralizing antibody.)
Antibody-mediated Immunity: also called humoral immunity. Immunity that results from the activity of antibodies in blood and lymphoid tissue.
Antigen: An antigen is a foreign substance or protein in the body that can trigger an immune response. This response results in the production of an antibody (a protein that is made by white blood cells) that works to combat the antigen with the other defenses of the immune system.
Apoptosis: cellular suicide, also known as programmed cell death. A possible mechanism used by HIV to suppress the immune system. HIV may cause apoptosis in both HIV-infected and HIV-uninfected immune system cells.
Approved Drugs: In the United States, the Food and Drug Administration (FDA) must approve a substance as a drug before it can be marketed. The approval process involves several steps including pre-clinical laboratory and animal studies, clinical trials for safety and efficacy, filing of a New Drug Application by the manufacturer of the drug, FDA review of the application, and FDA approval/rejection of application [See Food and Drug Administration].
Arm: A group of participants in a comparative clinical trial all of whom receive the same treatment, intervention or placebo. The other arm(s) receive(s) a different treatment. Most randomized trials have two "arms," which may be comparing either a new drug with a placebo, or comparing two drugs to each other. Some trials have three "arms," or even more. [See Randomized Trial].
ART: Formally known as HAART [Highly Active Antiretroviral Treatment], ART is defined as treatment with at least three active anti-retroviral medications (ARV’s), typically two nucleoside or nucleotide reverse transcriptase inhibitors (NRTI’s) plus a non-nucleoside reverse transcriptase inhibitor (NNRTI) or a protease inhibitor (PI) or another NRTI called abacavir (Ziagen). ART is often called the drug “cocktail” or triple-therapy. [See HIV Basics >Treatment Options and HIV Basics > Topic of the Month January 2003]
Attenuated Virus: A weakened virus. Attenuated viruses are often used as vaccines because they can no longer produce disease but still stimulate a strong immune response, like that to the natural virus. Examples of attenuated virus vaccines include oral polio, measles, mumps, and rubella vaccines.
Baseline: Information gathered at the beginning of a clinical trial, just before a participant starts to receive the treatment(s) that are part of the study. At this reference point, measurable values such as CD4 count are recorded. The safety and efficacy of a drug are often determined by monitoring changes from the baseline values.
bDNA (branched DNA) assay: A laboratory test for measuring the amount of virus in blood plasma which uses light to determine how much virus is present..
Bias: When someone's point of view prevents impartial judgment on an issue. In clinical studies, bias is controlled by blinding and randomization [See Blind and Randomization].
Blinded Study: A type of clinical trial in which participants don't know which "arm" of the study they are in. [See double blind study].
B-lymphocyte (B cell): one of the two major classes of lymphocytes, B lymphocytes are white blood cells of the immune system that are derived from the bone marrow and spleen. B cells develop into plasma cells, which produce antibodies.
CAB: Stands for Community Advisory Board. Every clinical research group should have an established CAB whose members are similar to people effected and affected by the HIV epidemic. They should reflect the age, gender, racial and ethnic populations, education, literacy, and languages of the community that is served by the research group. The Community Advisory Board assists the research team in the selection and implementation of studies. This multi-disciplinary group of volunteers works to integrate community involvement in order to advance HIV/AIDS research. An important mission of the CAB is to provide an opportunity for our affected communities to understand the clinical research process; voice concerns regarding specific clinical studies, their development, implementation and outcomes; give assistance concerning issues related to the recruitment and retention of study volunteers; advocate for the rights of study volunteers; forge a viable partnership that will lead to improved knowledge of HIV/AIDS disease; give a means to address grievance issues; and promote ethical research purposes and practices. Click here to read one of the NYU/Bellevue ACTU CAB member's take on what being part of a CAB is like.
CD4 Cell Count: A type of cell also known as "helper" T-cells, which help by mobilizing your immune defense when your body has an infection. [See Understanding Test Results].
CD8 T lymphocyte: A type of immune cell that carries the "cluster of differentiation 8" (CD 8) marker. These cells help destroy damaged, cancerous, or infected cells in the body. CD8 T cells may be cytotoxic T lymphocytes or suppressor T cells. [See also cytotoxic T lymphocyte (CTL): T cell].
Cell-mediated Immunity (cellular immunity): The immune response coordinated by helper T cells and CTLs. This branch of the immune system targets cells infected with microorganisms such as viruses, fungi and certain bacteria.
Chemistry Panel: Also known as Chemistry Screen; Measures essential chemicals produced by your blood and can help diagnose infections and drug side effects. [See Reading Test Results].
Clinical: Dealing with or about people based on medical findings as opposed to theoretical or laboratory-based findings.
Clinical Endpoint: See Endpoint. Clinical Investigator: A medical researcher in charge of carrying out a clinical trial's protocol.
Clinical Trial: A clinical trial is a research study designed to answer specific questions about vaccines or new therapies or new ways of using known treatments. Clinical trials (also called medical research and research studies) are used to determine whether new drugs or treatments are both safe and effective. Carefully conducted clinical trials are the fastest and safest way to find treatments that work in people. Trials occur in four phases: Phase I tests a new drug or treatment in a small group; Phase II expands the study to a larger group of people; Phase III expands the study to an even larger group of people; and Phase IV takes place after the drug or treatment has been licensed and marketed. [See Phase I, II, III, and IV Trials].
Cohort: a group of individuals with some characteristics in common. For example, a trial might include two cohorts, a group that has hepatitis and HIV, and a group that does not have hepatitis.
Complete Blood Count [CBC]: A measure of the health of your blood, including the quality and quantity of its white and red blood cells, the CBC includes 13 tests. 3 main tests: White Blood Cell Count (WBC), Hemoglobin (HGB), Platelets. [See Understanding Test Results]
Confidentiality Regarding Trial Participants: Refers to maintaining the confidentiality of trial participants including their personal identity and all personal medical information.
Contraindication: A specific circumstance when the use of certain treatments could be harmful.
Control Group: The control group in a clinical trial is the group of subjects that does not receive the experimental treatment or intervention, but receives either the currently approved standard treatment for the disease or an inactive substance [also called placebo].
Controlled Trials: Control is a standard against which experimental observations may be evaluated. In clinical trials, one group of participants is given an experimental drug, while another group (i.e., the control group) is given either a standard treatment for the disease or a placebo.
Cytokines: A protein produced by white blood cells, that acts as a messenger between cells. Cytokines can stimulate or inhibit the growth and activity of various immune cells. Cytokines are essential for a coordinated immune response. HIV replication is regulated by a delicate balance among the body's own cytokines. By altering that balance scientists have changed this replication in laboratories and potentially even in the body.
Cytotoxic T-lymphocyte (CTL): A lymphocyte that is able to kill foreign cells marked for destruction by the cellular immune system. CTLs can destroy cancer cells and cells infected with viruses, fungi, or certain bacteria. CTLs are also known as killer T cells; they carry the CD8 marker. CTLs kill virus-infected cells, whereas antibodies generally target free-floating viruses in the blood. See also CD8 (T8) Cells.
Data Safety and Monitoring Board [DSMB]: An independent committee, composed of both community representatives and clinical research experts, that reviews data while a clinical trial is in progress to ensure that participants are not exposed to undue risk. A DSMB may recommend that a trial be stopped if there are safety concerns or if the trial objectives have been achieved.
Detuned Assay: A detuned assay is a type of HIV test that attempts to determine how recently someone has been infected by looking for early versus mature antibodies. A Detuned Assay report that shows early antibodies may indicate that someone has been infected with HIV for 3 months or less. A Detuned Assay report that shows that someone has mature antibodies may indicate that they have been infected for longer than 3 months. At this time this test is only performed in research.
Dose-ranging Study: A clinical trial in which two or more doses of an agent (such as a drug) are compared to determine which dose works best and is most safe.
Double-blind Study: A clinical trial design in which neither the participating individuals nor the study staff knows which participants are receiving the experimental drug or vaccine and which are receiving the control (or another therapy). The control usually is either the currently-approved standard treatment or an inactive substance called a placebo. This design is often employed to reduce bias [See Single Blind ].
Drug-Drug Interaction: A modification of the effect of a drug when administered with another drug. The effect may be an increase or a decrease in the action of either substance, or it may be an adverse reaction that is not normally associated with either drug.
Drug Resistance: Occurs when the virus a person is infected with is no longer sensitive to a medication. Even when the viral load is undetectable, a small amount of virus is still present and copying itself in an HIV-positive person's body. The 'copies' (of the replicating viruses) that survive are those which the drug cannot suppress. These surviving copies have mutated and developed resistance to the medication. Sooner or later, the number of copies of this mutated virus will increase and may require someone to change their treatment.
Drug Resistance Testing: Measures which of the 16 HIV medications an infected person’s virus may have developed resistance to[See Reading Test Results].
DSMB: See Data Safety and Monitoring Board.
Efficacy: (Of a drug or treatment). The maximum ability of a drug or treatment to produce a result regardless of dosage. A drug passes efficacy trials if it is effective at the dose tested and against the illness for which it is prescribed. In the procedure mandated by the FDA, Phase II clinical trials gauge efficacy, and Phase III trials confirm it [See Food and Drug Administration] [See Phase 1, 2, 3, and 4 Trials].
Eligibility Criteria: The guidelines for who may or may not be enrolled in a research study. Eligibility criteria includes both the traits volunteers should have (also called Inclusion Criteria) and the traits volunteers should not have (also called Exclusion Criteria). [See Inclusion/Exclusion Criteria].
ELISA (enzyme-linked immunoabsorbent assay): The ELISA (also sometimes called EIA) is almost always the first test performed to determine if someone is HIV-positive; it is inexpensive and very sensitive for detecting the presence of HIV antibodies. In most cases, a blood sample is tested, but other types of ELISAs that use saliva and urine have also been developed. HIV ELISA tests are designed for the greatest sensitivity, which means it is designed to detect all persons with HIV antibodies and may also detect other proteins that are similar to HIV antibodies (called a false positive). A positive HIV ELISA test must be confirmed by a second, more specific test such as an HIV Western Blot to be certain that it is a true HIV infection.
Empirical: Based on experience or observational but not necessarily on scientific data proven in research studies.
Endpoint: The overall goal that a research study is investigating.
Envelop e(or viral envelope): The outer surface of a virus, also called the coat. Not all viruses have an envelope. (See also virus; env.)
Enzyme: A protein produced by cells to accelerate a specific chemical reaction. Enzymes are not altered by the chemical processes they affect. Enzymes are generally named by adding the ending "-ase" to the name of the substance on which the enzyme acts (for example, protease is an enzyme that acts on proteins).
Epidemiology: The branch of medicine that studies the number of new cases of a disease or condition, the way a disease or condition is distributed across different groups, and the methods of controlling a disease or condition..
Exclusion/Inclusion Criteria: See Inclusion/Exclusion Criteria.
FDA: See Food and Drug Administration.
Food and Drug Administration [FDA]: The U.S. Department of Health and Human Services agency responsible for ensuring the safety and effectiveness of all drugs, biologics, vaccines, and medical devices, including those used in the diagnosis, treatment, and prevention of HIV infection, AIDS, and AIDS-related opportunistic infections. The FDA also works with the blood banking industry to safeguard the nation's blood supply. Also see http://www.fda.gov/.
gp120: Also know as glycoprotein 120. One of the proteins that the envelope of HIV is made of. gp120 projects from the surface of HIV and binds to the CD4 molecule on helper T cells, which is part of the way HIV attacks the body's immune system. gp120 has been a focus of experimental HIV vaccine development because the outer envelope is the first part of the virus that encounters antibody and may be an important opportunity to prevent infection.
gp160: Also known as glycoprotein 160. It is a precursor of HIV envelope proteins gp41 and gp 120.
HAART: Stands for Highly Active Antiretroviral Treatment. HAART is defined as treatment with at least three active anti-retroviral medications (ARV’s), typically two nucleoside or nucleotide reverse transcriptase inhibitors (NRTI’s) plus a non-nucleoside reverse transcriptase inhibitor (NNRTI) or a protease inhibitor (PI) or another NRTI called abacavir (Ziagen). HAART is often called the drug “cocktail” or triple-therapy. [See HIV Basics >Treatment Options]
Half-life: the time required for half the amount of a substance to be eliminated from the body or to be converted to another substance(s).
Helper T-cell: lymphocyte bearing the CD4 marker. Helper T cells are the chief regulatory cells of the immune response. They are responsible for many immune system functions, including turning antibody production on and off, and are the main target of HIV infection. (See also CD4+ T lymphocyte.)
HIV Viral Set Point: The natural amount of HIV an HIV-positive person accumulates in their body after primary infection. The amount of virus differs from person to person.
Human Immunodeficiency Virus, type 1 (HIV-1): The retrovirus isolated and recognized as the cause of AIDS. HIV-1 is classified as a lentivirus in a subgroup of retroviruses. The genetic material of a retrovirus such as HIV is RNA . HIV converts its RNA into DNA and inserts into the host cell's DNA, preventing the host cell from carrying out its natural functions and turning it into an HIV factory.
Human Immunodeficiency Virus, type 2 (HIV-2): A virus closely related to HIV-1 that has also been found to cause AIDS. It was first isolated in West Africa. Although HIV-1 and HIV-2 are similar viruses, are transmitted in the same way, and cause the same sorts of illness, HIV-2 is less aggressive than HIV-1 and does not always react to HIV medications in the same way as HIV-1.
Hypothesis: The idea or assumption which is the basis of an argument or research study.
Immune Complex: The result of a reaction between an antigen, or foreign substance, and the antibody which the body has made to fight it. This combination of antigen bound by antibody may or may not cause adverse effects in a person.
Immune Deficiency: A breakdown or inability of certain parts of the immune system to function, thus making a person susceptible to diseases (or “opportunistic infections”) that they would not ordinarily develop.
Immunity: nNatural or acquired resistance provided by the immune system to a specific disease. Immunity may be partial or complete (meaning someone may or may not be totally immune to a disease), specific or nonspecific (meaning that the immunity may apply to a single disease or multiple diseases), long-lasting or temporary (meaning the immunity may last someone's entire life or may eventually go away).
Immunization: The process of inducing immunity by administering an antigen (vaccine) that is derived from or similar to the substance that causes the illness, in order to allow the immune system to prevent infection or illness if it later comes in contact with that disease.
Immunogen: a substance capable of provoking an immune response. Also called an antigen.
Immunogenicity: the ability of an antigen or vaccine to stimulate immune responses.
Immunotherapy: a treatment that stimulates or modifies the body's immune response.
Inclusion/Exclusion Criteria: The medical or social standards determining whether a person may or may not be allowed to enter a clinical trial. These criteria are based on such factors as age, gender, the type and stage of a disease, previous treatment history, and other medical conditions. It is important to note that inclusion and exclusion criteria are not used to reject people personally, but rather to identify appropriate participants and keep them safe.
IND: See Investigational New Drug.
informed consent: The process of learning the key facts about a clinical trial before deciding whether or not to participate. It is also a continuing process throughout the study to provide information for participants. To help someone decide whether or not to participate, the doctors and nurses involved in the trial explain the details of the study. There is also an informed consent document which states why the particular clinical trial is being done, what procedures will be done during the course of the study, what possible risks there may be and information about the rights and responsibilities of a study participant. This document must be signed by the clinical trial participant before any study procedure can begin.
Informed Consent Document: A document that describes the rights of the study participants, and includes details about the study, such as its purpose, duration, required procedures, and key contacts. Risks and potential benefits are explained in the informed consent document. The participant then decides whether or not to sign the document. Informed consent is not a contract, and the participant may withdraw from the trial at any time.
Institutional Review Board [IRB]: 1. A committee of physicians, statisticians, researchers, community advocates, and others that ensures that a clinical trial is ethical and that the rights of study participants are protected. All clinical trials in the U.S. must be approved by an IRB before they begin. 2. Every institution that conducts or supports biomedical or behavioral research involving human participants must, by federal regulation, have an IRB that initially approves and periodically reviews the research in order to protect the rights of human participants.
Intent to Treat: Analysis of clinical trial results that includes all data from participants in the groups to which they were randomized [See Randomization] even if they never received or discontinued the treatment or if they leave the study before completing all the required visits.
Intervention Name: The generic name of the precise intervention being studied.
Intervention: Primary interventions being studied. Types of interventions are Drug, Gene Transfer, Vaccine, Behavior, Device, or Procedure.
Investigational New Drug: A new drug, antibiotic drug, or biological drug that is used in a clinical investigation. It also includes a biological product used in vitro for diagnostic purposes. Investigational New Drug is a status given to an experimental drug after the FDA agrees that it can be tested in people.
In vitro: an artificial environment created outside a living organism (e.g., in a test tube or culture plate) used in experimental research to study a disease or biological process.
In vivo: testing within a living organism, e.g., human or animal studies.
Isolate: a particular strain of HIV-1 taken from a person.
IRB: See Institutional Review Board.
Lactic Acidosis: A serious, sometimes life-threatening condition, caused by very high levels of lactic acid in the blood which causes the body's tissues to not get enough oxygen. The liver normally breaks down lactic acid therefore levels of lactic acid can increase when the liver is severely damaged or diseased.
Lipoatrophy: Lipoatrophy is abnormal fat loss, often in the face, arms, and legs which may alter someone's appearance. Fat inside the abdomen may also increase.
Lipodystrophy: A condition in which the body produces, uses, and disproportionately distributes fat. Lipodystrophy may also be referred to as "buffalo hump," "protease paunch," "crixivan potbelly," or "AIDS belly." Lipodystrophy is thought to be related to the use of protease inhibitor and NRTI drugs, though how these drugs may cause or trigger lipodystrophy is not yet known. Lipodystrophy symptoms involve the loss of the thin layer of fat under the skin, making veins seem to protrude, wasting of the face and limbs, and the accumulation of fat on the abdomen (both under the skin and within the abdominal cavity) or between the shoulder blades.
Live-vector vaccine: A vaccine that uses an organism that does not cause illness, like a virus or bacterium, to transport HIV or other foreign genes into the body to stimulate an immune response. This type of vaccine is important because it is particularly capable of inducing CTL activity (CTLs, or cytotoxic t lymphocytes, kill virus-infected cells in the body). Examples of harmless organisms used as live vectors in HIV vaccines are canarypox, vaccinia, and adenovirus.
Lymphocyte: A type of white blood cell produced in the lymphoid organs that is primarily responsible for immune responses which is in the blood, lymph and lymphoid tissues. (See also B cell and T cell.)
Lymphoid Tissues: The tonsils, adenoids, lymph nodes, spleen, thymus, and other tissues. These organs act as the body's filtering system, trapping invaders (foreign particles such as bacteria and viruses) and presenting them to squadrons of immune cells that gather in the tissue.
Lymphoma: Cancer of the lymphoid tissues. Lymphomas are often described as being large cell or small cell types, cleaved or non-cleaved, and diffuse or nodular. The different types often have different prognoses (i.e., prospect of survival or recovery). Lymphomas can also be referred to by the organs where they are active, such as CNS lymphomas, which are in the central nervous system, and GI lymphomas, which are in the gastrointestinal tract. The types of lymphomas most commonly associated with HIV infection are called non-Hodgkin's lymphomas or B cell lymphomas. In these types of cancers, certain cells of the lymphatic system grow abnormally and divide rapidly, growing into tumors.
Macrophage: A large immune system cell in the body that devours invading organisms and other intruders. Macrophages stimulate other immune cells by presenting them with small pieces of the invaders. Macrophages can harbor large quantities of HIV without being killed, acting as reservoirs of the virus.
Memory Cell: Memory cells are a type of T cells and B cells that have been exposed to specific foreign substances. If someone becomes exposed to that foreign substance again memory cells can "proliferate," recognize the foreign substance and divide more easily, to help the body fight it off.
Mucosal Immunity: Resistance to infection across the mucous membranes. Mucosal immunity depends on immune cells and antibodies present in the linings of reproductive tract, gastrointestinal tract and other moist surfaces of the body which are exposed to the outside world.
Natural History Study: Study of the development of something (such as an organism or a disease) over a period of time as it would occur naturally. Natural history studies do not involve any interventions or treatment.
Neuropathy: The name given to a group of disorders involving nerves. Symptoms range from a tingling sensation or numbness in the toes and fingers to paralysis. Neuropathy can be a result of HIV infection or a side-effect of antiretroviral therapy. It is estimated that 35% of persons with HIV disease have some form of neuropathy. [See Peripheral Neuropathy]
Neutralizing Antibody: An antibody that keeps a virus from infecting a cell, usually by blocking receptors on the cell or the virus.
Neutropenia: An abnormal decrease in the number of neutrophils, the most common type of white blood cells, in the blood. Someone experiencing neutropenia may lose some or all of their neutrophils. Neutropenia may also be associated with HIV infection or may be a side-effect to medications.
New drug application [NDA]: An application submitted by the manufacturer of a drug to the FDA after clinical trials have been completed for a license to market a drug to the public for a specific illness.
NK cell (or natural killer cell): A non-specific lymphocyte. NK cells, like killer T cells, attack and kill cancer cells and cells infected by microorganisms. NK cells are "natural" killers because they do not need to recognize a specific antigen in order to attack and kill.
Non-Hodgkin's Lymphoma (NHL): A lymphoma, or cancer of the lymphoid tissues, made up of B cells and characterized by nodular or diffuse tumors that may appear in the stomach, liver, brain, and bone marrow of persons with HIV. After Kaposi's Sarcoma, NHL is the most common opportunistic cancer in persons with AIDS.
Normalized Inhibitory Quotient [NIQ]: A measure which tells the amount a specific drug would have to be increased to stop HIV from growing in your blood and lower your viral load.
Nucleic Acid: An organic substance found in all living cells, in which hereditary information is stored and from which it can be transferred. Nucleic acid molecules are long chains that generally occur in combination with proteins. The two chief types are DNA (deoxyribonucleic acid), found mainly in the center of a cell called the nuclei, and RNA (ribonucleic acid), found mostly in the outer parts of the cell called the cytoplasm.
Nucleoside: A building block of nucleic acids, either DNA or RNA, found in living organisms. Nucleosides are nucleotides without certain chemical compounds called phosphate groups.
Nucleoside Reverse Transcriptase Inhibitor (NRTI): A type of antiretroviral drug whose chemical structure is made up of a modified version of a natural nucleoside. These compounds suppress reproduction of retroviruses by interfering with reverse transcriptase enzyme, a protein needed for HIV to reporduce.
Nucleotide: Nucleotides are the building blocks of nucleic acids, DNA and RNA. Nucleotides are composed of phosphate groups, a five-sided sugar molecule (ribose sugars in RNA, deoxyribose sugars in DNA), and nitrogen-containing bases. These fall into two classes: pyrimidines and purines. A nucleotide without its phosphate group is called a nucleoside.
Off-label use: A drug prescribed for a condition other than those approved by the FDA.
Open-label trial: A research study in which both the study doctor and volunteers know which medications or vaccines volunteers are receiving.
Opportunistic Infection: An illness caused by an organism that usually does not cause disease in a person with a normal immune system. People with advanced HIV infection suffer opportunistic infections of the lungs, brain, eyes and other organs.
p24: A protein in HIV's inner core. The p24 antigen test looks for the presence of this protein in a person's blood to determine if someone is HIV-positive.
Pathogen: Any disease-producing microorganism or material.
Pathogenesis: The origin and development of a disease. More specifically, it's the way a microbe (bacteria, virus, etc.) causes disease in a person.
Polymerase Chain Reaction (PCR): A sensitive laboratory technique used to detect the amount of HIV RNA in the blood. A PCR is used to measure viral load in persons infected with HIV and also can be used to detect an HIV infection before a standard HIV test would, such as in our research-based enhanced HIV screening First Call NYU.
Peer Review: Review of a research study by experts chosen by the study sponsor. These experts review the trials for scientific merit, safety of volunteers, and ethical considerations.
Peptide: A short compound formed by linking two or more amino acids. Proteins are made of multiple peptides.
Pharmacokinetics: The processes of absorption, distribution, metabolism and excretion of a drug or vaccine.
Phase 1 Trials: A closely monitored research study of a drug or vaccine conducted in a small number of healthy volunteers. A Phase 1 trial is designed to determine a drug or vaccine's safety in humans, metabolism or the way it is processed by the body, pharmacologic actions or the way it works in the body, and possible side-effects.
Phase 2 Trials: A research study of a drug or vaccine to identify common short-term side effects and risks and to collect early information on its effectiveness against the disease being studied. Phase 2 trials enroll volunteers who are similar to the people who the drug or vaccine is intended to help. Phase 2 trials may enroll up to several hundred participants and may have more than one arm.
Phase 3 Trials: An expanded research study conducted after previous researcg suggests that a drug or vaccine may be effective at a specific dose and schedule. Phase 3 trials are also intended to gather additional information about safety needed to evaluate the overall benefits and possible harm a drug a vaccine might cause and gather information doctors need to prescribe the drug or vaccine to people. Phase 3 trials usually include several hundred to several thousand volunteers.
Phase 4 Trials: Research studies conducted after a drug or vaccine is approved by the FDA to gather additional information about possible risks, possible benefits, and the best way to use the drug or vaccine.
Phosphate: A substance (called an electrolyte) that carries an electrical charge when dissolved in blood. Most of the body's phosphate (about 85%) is found in bones. The rest of it is stored in tissues throughout the body. (Electrolytes are minerals found naturally in the body. They include potassium, calcium, sodium, and magnesium. Electrolytes are needed to fight infection and to keep the body's balance of fluids at the proper level and to maintain normal functions, such as heart rhythm, muscle contraction, and brain function.)
Placebo: A placebo is an inactive pill, liquid, or powder that has no treatment value. In clinical trials, experimental treatments are often compared with placebos to assess the treatment's effectiveness. In some studies, the participants in the control group will receive a placebo instead of an active drug or treatment. No sick participant receives a placebo if there is a known beneficial treatment. [See Placebo Controlled Study].
Placebo-controlled Study: A method of investigation of drugs in which an inactive substance (the placebo) is given to one group of participants, while the drug being tested is given to another group. The results obtained in the two groups are then compared to see if the investigational treatment is more effective in treating the condition.
Placebo Effect: A physical or emotional change, occurring after a substance is taken or administered, that is not the result of any special property of the substance. The change may be beneficial, reflecting the expectations of the participant and, often, the expectations of the person giving the substance.
Polyvalent Vaccine: a vaccine that is produced from multiple viral strains, or is made to induce immune responses against multiple strains.
Preclinical: Refers to the testing of experimental drugs in the test tube or in animals - the testing that occurs before trials in humans may be carried out.
Prevention Trials: Refers to trials to find better ways to prevent disease in people who have never had the disease or to prevent a disease from returning. These approaches may include medicines, vitamins, vaccines, minerals, or behavioral changes.
Preventive HIV Vaccine: a vaccine designed to prevent getting infected from HIV.
Primary Care Provider (PCP): Refers to a health care professional who provides you with comprehensive medical care. A Primary Care Provider can be a medical doctor or physician [MD], a physician’s assistant [PA] or a nurse practitioner [NP]. He or she conducts your regular physical exams and takes care of your health care needs. When necessary, your primary care provider refers you to a specialist for further examination and treatment.
Prophylaxis: prevention of disease.
Protease Inhibitor: one of a class of anti-HIV drugs designed to inhibit the enzyme protease and interfere with virus replication. Protease inhibitors prevent HIV precursor proteins from dividing into smaller cells of active proteins, a process that normally occurs when HIV reproduces.
Protocol: protocol: the detailed plan for a clinical trial that is designed to answer specific research questions. The protocol describes what types of people may participate in the trial; the schedule of tests, procedures, medications, and dosages; and, the length of the study. While in a clinical trial, participants are seen at regular visits which have been determined in the protocol. At these visits, the research staff monitors participants’ health and may take blood or perform other tests to evaluate the safety and effectiveness of the treatment. [See Inclusion/Exclusion Criteria].
Quality of Life Trials [or Supportive Care Trials]: Refers to trials that explore ways to improve comfort and quality of life for individuals with a chronic illness.
Randomized Trial: a study in which participants are assigned by chance to one of two or more intervention arms or regimens. Randomization minimizes the differences among groups by equally distributing people with particular characteristics among all the trial arms. [See Arm and Placebo].
Receptor: a molecule on the surface of a cell that serves as a recognition or binding site for antigens, antibodies or other cellular or immunologic components.
Recombinant DNA Technology: the technique by which genetic material from one organism is inserted into a foreign cell in order to mass produce the protein encoded by the inserted genes.
Resistance Testing:
There are three types of resistance testing:
- Genotype Testing: a type of resistance test that looks for changes (mutations) in HIV that may be associated with drug resistance (this is when HIV is no longer controlled by drugs).
- Phenotype Testing: a kind of resistance testing that, instead of using mutation analysis, grows the virus in the presence of various concentrations of drug to see which drugs the HIV is still sensitive to (not resistant to). Standard phenotype tests take approximately 4 weeks to show results and the test is very expensive.
- Virtual Phenotype: a system used to give the same information as the standard phenotype test – that is, information about which drugs will work to control the HIV – by comparing information gathered from over 35,000 actual phenotype tests to see which drugs will still have an effect on those mutations. This is done by entering the results from a genotype test into the database of available information. All these tests can be very helpful in making treatment decisions about which medications will work against the mutations one has developed in order to try to get the HIV under control and reduce viral load.
Retrovirus: HIV and other viruses that carry their genetic material in the form of RNA rather than DNA and have the enzyme, reverse transcriptase, that can transcribe it into DNA. In most animals and plants, DNA is usually made into RNA, hence "retro" is used to indicate the opposite direction.
Reverse Transcriptase: the enzyme produced by HIV and other retroviruses that enables them to direct a cell to synthesize DNA from their viral RNA.
Risk-benefit Ratio: The risk to individual participants versus the potential benefits. The risk/benefit ratio may differ depending on the condition being treated.
RNA (ribonucleic acid): a single-stranded molecule composed of chemical building blocks, similar to DNA. The RNA segments in cells represent copies of portions of the DNA sequences in the nucleus. RNA is the sole genetic material of retroviruses.
Screening Trials: Refers to trials that test the best way to detect certain diseases or health conditions.
Serostatus: positive or negative results of a diagnostic test, such as an ELISA, for a specific antibody, in this case HIV.
Side Effects: Any undesired actions or effects of a drug or treatment. Negative or adverse effects may include headache, nausea, hair loss, skin irritation, or other physical problems. Experimental drugs must be evaluated for both immediate and long-term side effects [See Adverse Reaction].
Single-blind Study: A study in which one party, either the investigator or participant, is unaware of what medication the participant is taking. [See Blind and Double-Blind Study].
Standard Treatment: A treatment currently in wide use and approved by the FDA, considered to be effective in the treatment of a specific disease or condition.
Standards of Care: Treatment regimen or medical management based on state of the art participant care.
Statistical Significance: the probability that an event or difference occurred as the result of the intervention (drug or vaccine) rather than by chance alone. This probability is determined by using statistical tests to evaluate collected data. Guidelines for defining significance are chosen before data collection begins.
Stratification: separation of a study cohort into subgroups or strata according to specific characteristics such as age, gender, etc., so that these differences which might affect the outcome of the study, can be taken into account.
Sterilizing Immunity: an immune response that completely prevents the establishment of an infection.
Study Endpoint: A primary or secondary outcome used to judge the effectiveness of a treatment
Study Type: The primary investigative techniques used in an observational protocol; types are Purpose, Duration, Selection, and Timing.
Surrogate Marker: an indirect measure of disease progression. In HIV disease, the number of CD4+ T cells per cubic millimeter of blood is often used as a surrogate marker.
Therapeutic HIV Vaccine: a vaccine designed to boost the immune response to HIV in a person already infected with the virus. Also referred to as an immunotherapeutic vaccine.
T-lymphocyte Proliferation Assay: The Lymphocyte Proliferation Assay (LPA) is a test used to measure how well a person’s immune system is functioning by testing the memory of T cells to recognize antigens or microbes such as candida, tetanus toxoid (TT)., cytomegalovirus (CMV) antigen, varicella zoster virus (VZV) antigen, and HIV-1 antigens (e.g., gp120 and p24) This proliferative response of lymphocytes occurs only if the patient has been immunized to that antigen, either by having recovered from an infection with the microorganism containing that antigen, or by having been vaccinated. Most people will respond to at least one of several common microbial antigens. LPA can be used to measure improvements in immunological function following antiretroviral therapy, to measure the development of anti-HIV immune responses following the administration of an HIV-vaccine, and to detect the presence of immune responses against specific opportunistic pathogens.
toxicity: An adverse effect produced by a drug that is detrimental to the participant's health. The level of toxicity associated with a drug will vary depending on the condition which the drug is used to treat.
Treatment IND: IND stands for Investigational New Drug application, which is part of the process to get approval from the FDA for marketing a new prescription drug in the U.S. It makes promising new drugs available to desperately ill participants as early in the drug development process as possible. Treatment INDs are made available to participants before general marketing begins, typically during Phase III studies. To be considered for a treatment IND a participant cannot be eligible to be in the definitive clinical trial.
Treatment Trials: Refers to trials which test new treatments, new combinations of drugs, or new approaches to surgery or radiation therapy.
Vaccine: a preparation that stimulates an immune response that can prevent an infection or create resistance to an infection.
Vaccinia: a cowpox virus, formerly used in human smallpox vaccines. Employed as a vector in HIV vaccines to transport HIV genes into the body.
Vector: in vaccine research, a bacterium or virus that does not cause disease in humans and is used in genetically engineered vaccines to transport genes coding for antigens into the body to induce an immune response. (See also vaccinia and canarypox.)
Viral Load: Measures the amount of new HIV produced and released into a person’s bloodstream. [See Understanding Test Results]
Viremia: the presence of virus in the bloodstream.
Virus: a microorganism composed of a piece of genetic material : RNA or DNA : surrounded by a protein coat. To replicate, a virus must infect a cell and direct its cellular machinery to produce new viruses.
Western Blot: a blood test to detect antibodies to several specific components of a virus such as HIV. This test is most often used to confirm a positive ELISA.
Below is a photograph of a Western Blot tests. This series of tests illustrates how an HIV test result can change during the window period from HIV-negative to HIV-positive.
Each column is one Western Blot test. On the left side of the image there are two columns to be used as points of comparison. The column marked "PC" is an HIV-positive test result and the column marked "NC" is an HIV-negative test result. Column 3 to Column 10 are tests performed on a single person beginning with the day when the person was first exposed to HIV (Column 3, Day 0) to when the person had a full-blown HIV infection (Column 10, Day 30). An HIV infection is not the same as an AIDS diagnosis. This series records the process during which a person's immune system produces a response to an HIV infection. Each black or dark grey horizontal stripe is representative of the presence of a different antibody against a protein found in HIV. To be conclusive (HIV-positive), a Western Blot must have 5 horizontal stripes.
Window Period: The ‘window period’ is period between an exposure and the time it can take to develop antibodies. If you take a HIV test during the "window period” the results may not be a true reflection of your HIV status.