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AIDS Medical Glossary and Drug Chart
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Definitions are given by the full name of the term or generic
name of the drug, not by the abbreviation or brand name. For example,
the definition of KS will be found under Kaposi's Sarcoma. The
only abbreviations commonly used within definitions are HIV, AIDS,
RNA, DNA, and FDA.
Terms used that are defined elsewhere in the Glossary are in CAPITALS.
The drug chart lists alternative names for commonly prescribed
medications.
K
K Cell: A type of nonspecific LYMPHOCYTE that
seeks out and kills any cells coated with any ANTIBODY. (The cells
become coated because they are infected with VIRUS and display
viral PROTEINS on their surface membranes.)
Kaplan-Meier Curve: a method for analyzing a
therapy's EFFICACY or TOXICITY by graphically displaying "survival" or
the occurrence of a study ENDPOINT or dropout. The Kaplan-Meier
curve displays a statistical estimate of the percent of people
receiving a given therapeutic REGIMEN who, at each observation
point after entering a trial, continue to do acceptably well on
their assigned therapy. Plotting the curves for a trial's different
treatment ARMS on the same chart yields a comparison of the various
regimens.
Kaposi's Sarcoma (KS): an AIDS-DEFINING ILLNESS
consisting of individual cancerous lesions caused by an overgrowth
of blood vessels. KS typically appears as pink or purple painless
spots or nodules on the surface of the skin or oral cavity. KS
also can occur internally, especially in the intestines, LYMPH
NODES and lungs, and in this form is life-threatening. KS is most
likely triggered by a species of HERPES VIRUS similar to EPSTEIN-BARR
VIRUS (see HHV-8). Up to now, KS has been treated with ALPHA INTERFERON,
radiation therapy (outside the oral cavity), and various systemic
and intralesional cancer CHEMOTHERAPIES. Possible antiviral remedies,
such as CIDOFOVIR and FOSCARNET, are now being examined, as well
as TOPICAL treatments.
Kaposi's Sarcoma Herpes Virus: see HHV-8.
Karnofsky Performance Score: a scale for analyzing
a patient's ability to perform certain ordinary tasks: 100
- normal, no complaints; 70 - unable to carry on normal activity;
50 - requires considerable assistance; 40 - disabled; 30 - hospitalization
recommended.
Ketoconazole (Nizoral): an antifungal medication
available in pill and liquid form that is effective against a variety
of fungal infections such as oral, vaginal and esophageal THRUSH
and cryptococcosis (see CRYPTOCOCCUS). Persons taking ketoconazole
must have their liver function tested periodically because of the
slight danger of serious liver damage.
Kidney Stone: a painful solid mass in the kidney
or urinary system, caused by the solidification or precipitation
of a dissolved substance in the urine.
Killer Cell: a generalized name for IMMUNE SYSTEM
cells that kill cancerous and VIRUS-infected cells. Among the killer
cells are killer T CELLS (CYTOTOXIC T LYMPHOCYTES), NATURAL KILLER
CELLS and K CELLS.
Killer T Cell: see CYTOTOXIC T LYMPHOCYTE.
KS: see KAPOSI'S SARCOMA.
KSHV: see HHV-8.
L
Lactic Acidosis: a rare but deadly metabolic
disorder. Symptoms can include weight loss, fatigue, malaise, nausea,
vomiting, abdominal pain, shortness of breath and low SERUM bicarbonate
levels. NUCLEOSIDE ANALOGS have been associated with mitochondrial
toxicity, which can lead to lactic acidosis.
Lactobacillus: BACTERIA that create lactic acid.
Lactose Intolerance: the inability to digest
milk products due to the lack of the ENZYME lactase, which breaks
down milk sugar (lactose).
Lamivudine (3TC, Epivir): a NUCLEOSIDE ANALOG
from GlaxoSmithKline with anti-HIV and anti-HEPATITIS B activity.
Most common SIDE EFFECTS are nausea, headache, fatigue, diarrhea
and ANEMIA.
Langerhans Cell: the type of DENDRITIC CELL found
in the skin.
Last Observation Carried Forward (LOCF): a type
of data analysis in CLINICAL TRIALS in which the last results before
a subject drops out of the trial are counted as if they occurred
at the end of the trial. Used when data are missing due to loss
to follow-up.
Late Breaker: a presentation at a scientific
conference that was submitted too late to be included in the original
program but that was deemed to merit inclusion in the conference.
Latency: a QUIESCENT period during a disease
process. Clinical latency is an ASYMPTOMATIC period in the early
years of HIV infection. The period of latency is characterized
in the peripheral blood by stable, slightly depressed CD4 CELL
COUNTS and low HIV levels. Research indicates that HIV remains
quite active in the LYMPH NODES during this period. Cellular latency
is a condition that exists in some cells after HIV has integrated
its GENOME into the cell's DNA but has not yet begun to replicate.
Cellular latency may last for years, making the eradication of
HIV from the body unlikely.
Lavage: the process of washing out an internal
organ or cavity for treatment or to obtain a sample.
L-Carnitine: a naturally occurring cell constituent
that modulates fat METABOLISM, in particular the mitochondrial
intake of LIPID derivatives. L-carnitine has been proposed as a
treatment for WASTING SYNDROME and the MYOPATHY associated with
AZT (ZIDOVUDINE).
LDL Cholesterol: see LOW DENSITY LIPOPROTEIN
CHOLESTEROL.
Lean Body Mass: the body's muscle and organ tissue.
Lecithinized Superoxide Dismutase (PC-SOD): a
synthetic version of superoxide dismutase (SOD), one of the more
potent ANTIOXIDANTS produced by the body.
Lentivirus: a subgroup of the RETROVIRUS family
that includes HIV and is characterized by long periods of clinical
LATENCY after infection.
Lesion: a disturbed area of tissue - a wound,
ulcer, injury, nodule or tumor on the skin or elsewhere.
Leukine: see GRANULOCYTE-MACROPHAGE COLONY STIMULATING
FACTOR.
Leukocyte: any of the various white blood cells,
which together make up the IMMUNE SYSTEM. NEUTROPHILS, LYMPHOCYTES
and MONOCYTES are all leukocytes.
Leukocytosis: an abnormally high number of LEUKOCYTES,
or white blood cells, in the blood. This condition can occur during
many types of infection and INFLAMMATION.
Leukopenia: an abnormally low number of total
LEUKOCYTES, or white blood cells, circulating in the blood, frequently
the result of drug-induced BONE MARROW SUPPRESSION.
LFT: see LIVER FUNCTION TEST.
Libido: sex drive.
Licorice: see GLYCYRRHIZIN.
Ligand: any molecule that binds to the surface
of another molecule, such as an immune cell RECEPTOR. For examples
of receptors see CCR5, CXCR-4, CD4.
Limit of Detection: refers to the SENSITIVITY
of a quantitative diagnostic test, such as the VIRAL LOAD ASSAY.
The limit of detection is the level below which the test can no
longer accurately measure the amount of a substance, such as HIV
RNA. If a person has an "undetectable" viral load, it
does not mean that HIV is no longer present, but rather, that the
test is not sensitive enough to measure the amount (see also RESERVOIR).
Also called the limit of quantification.
Limit of Quantification: see LIMIT OF DETECTION.
LIP: see LYMPHOID INTERSTITIAL PNEUMONITIS.
Lipid: a fatty substance.
Lipitor: see ATORVASTATIN.
Lipodystrophy: a disturbance of fat METABOLISM
that involves the absence of fat and/or the abnormal distribution
of fat in the body. Currently, "lipodystrophy" is not
clearly defined and the term is used to refer to a variety of SYNDROMES,
including wasting in the face and extremities, an accumulation
of abdominal fat and breast enlargement. The cause is unknown,
but it could be a result of HIV infection and/or ANTIRETROVIRAL
therapy.
Lipomas: tumors consisting of fat cells.
Lipomatosis: A disorder characterized by deposits
of fat beneath the skin of the neck, upper body, arms and legs.
The origin is uncertain, but it is thought to be genetic. Lipomatosis
often occurs in conjunction with alcoholic liver disease, macrocytic
ANEMIA and PERIPHERAL NEUROPATHY. It usually affects men and is
most common in the Mediterranean.
Lipoprotein: a chemical compound made of fat
and PROTEIN. Lipoproteins are found in the blood, where they carry
CHOLESTEROL.
Liposome: microscopic globules of LIPIDS manufactured
to enclose medications. The liposome's fatty layer is supposed
to protect and confine the enclosed drug until the liposome adheres
to the outer membrane of target cells. By delivering treatments
directly to the cells needing them, drug EFFICACY may be increased
while overall TOXICITY is reduced.
Liposuction: a surgical procedure in which fat
deposits are suctioned from specific parts of the body, e.g., the
abdomen, buttocks, hips, thighs, or back. Liposuction is sometimes
used to treat truncal adiposity or BUFFALO HUMP, although results
can vary.
Liver Enzyme: see both ALANINE AMINOTRANSAMINASE
and ASPARTATE AMINOTRANSAMINASE.
Liver Function Test (LFT): a test that measures
the blood SERUM level of any of several ENZYMES produced by the
liver. An elevated liver function test is a sign of possible liver
damage.
LOCF: see LAST OBSERVATION CARRIED FORWARD.
Log (Logarithm): formally, the number of times
ten must be multiplied with itself to equal a certain number. For
example, log 5 is 100,000 (10 x 10 x 10 x 10 x 10). VIRAL LOAD
is often reported in terms of log. In addition, logs are used to
measure changes in viral load. For example, a reduction in viral
load from 100,000 to 1,000 copies/ml is a 2.0 log (or 99 percent)
reduction (100,000 divided by 100 [2.0 log or 10 x 10] equals 1,000).
Note that while a one log reduction is a ten-fold difference, a
half log change is not a five-fold difference, rather a change
of 3.16-fold (the square root of ten) because 100.5 or
101⁄2 = 3.16.
Logarithm: see LOG.
Long-Term Nonprogressor: an individual who has
been infected with HIV for at least seven to twelve years (different
authors use different time spans) and yet retains a CD4 CELL COUNT
within the normal range and no evidence of disease progression.
Long-Term Survivor: a looser term than LONG-TERM
NONPROGRESSOR that indicates any person with any stage of HIV infection,
including AIDS, who has been stable over a period of years.
Long Terminal Repeat (LTR): the genetic material
at each end of a genetic sequence. When the HIV genes are integrated
into a cell's own GENOME, the LTR interacts with cellular and viral
factors to initiate the transcription of the HIV DNA into an RNA
form that is packaged in new VIRUS particles. Activation of the
LTR is a major step in triggering HIV replication.
Longitudinal Study: a study that follows patients
over an extended period of time.
Lopid: see GEMFIBROZIL.
Lopinavir (Kaletra, LPV): a PROTEASE INHIBITOR
made by Abbott Laboratories. Kaletra (LPV/r) is a combination of
lopinavir and a low dose of RITONAVIR, a drug that improves blood
levels of lopinavir.
Lotrimin: see CLOTRIMAZOLE.
Lovastatin: a CHOLESTEROL-lowering drug.
Low Density Lipoprotein (LDL) Cholesterol: a
LIPOPROTEIN that contains more fat than PROTEIN, often called "bad
cholesterol."
LP: see LUMBAR PUNCTURE.
LTR: see LONG TERMINAL REPEAT.
Lumbar Puncture (LP): insertion of a needle into
the lower spinal canal to obtain a sample of CEREBROSPINAL FLUID.
Also called a spinal tap.
Lymph Fluid: a transparent, slightly yellow fluid
that carries LYMPHOCYTES to and from the LYMPH NODES and helps
to collect foreign MICROBES. Lymph is derived from tissue fluids.
The fluid passes through the lymphatic ducts and then enters the
bloodstream.
Lymph Gland: see LYMPH NODE.
Lymph Node: small bean-sized organs made up mostly
of densely packed LYMPHOCYTES, LYMPH FLUID and connective tissue.
Clusters of lymph nodes are widely distributed in the body and
are essential to the functioning of the immune system. They are
the main sites where acquired immune responses are launched (see
IMMUNE SYSTEM and NAIVE T CELL). Lymph nodes are connected with
each other, other lymphoid tissue and the blood by the LYMPHATIC
VESSELS.
Lymphadenopathy: swelling or enlargement of the
LYMPH NODES due to infection or cancer. The swollen nodes may be
palpable or visible from outside the body.
Lymphatic Vessels: a body-wide network of channels,
similar to the blood vessels, that transports LYMPH FLUID to the
lymphoid tissue and into the bloodstream.
Lymphocyte: white blood cells that mature and
reside in the lymphoid organs and are responsible for the acquired
immune response (see IMMUNE SYSTEM). The two major types of lymphocytes
are T CELLS and B CELLS.
Lymphoid Interstitial Pneumonitis (LIP): a type
of pneumonia that affects 35 to 40 percent of children with AIDS
and causes hardening of the lung membranes involved in absorbing
oxygen. LIP is an AIDS-DEFINING ILLNESS in children.
Lymphoid Tissue: the organs of the lymph system
throughout the body, including the BONE MARROW, THYMUS, LYMPH NODES,
SPLEEN, tonsils, PEYER'S PATCHES and LYMPHOCYTE aggregates on mucosal
surfaces.
Lymphokine: a substance produced by LYMPHOCYTES
to precipitate various immune reactions. Lymphokines include the
INTERFERONS and INTERLEUKINS and are a subset of the CYTOKINE family.
Lymphoma: a cancer of the LYMPHOID TISSUE, largely
a solid tumor with cells arising from proliferating LYMPHOCYTES.
Symptoms may include LYMPH NODE swelling, weight loss and fever.
Some examples of lymphomas are BURKITT'S LYMPHOMA, HODGKIN'S DISEASE
and NON-HODGKIN'S LYMPHOMA. Treatment involves radiation therapy
(radiotherapy), CHEMOTHERAPY or both.
Lymphoproliferative Response: a specific IMMUNE
RESPONSE that entails rapid T CELL replication. Standard ANTIGENS,
such as tetanus toxoid, that elicit this response are used in lab
tests of immune competence.
Lysis: the splitting and dissolution of cellular
or viral material by chemical action.
M
MAC: see MYCOBACTERIUM AVIUM COMPLEX.
Macrophage: a large scavenger cell that ingests
degenerated cells and foreign organisms. Macrophages exist in large
numbers throughout the body and contribute to the development of
acquired immunity by acting as ANTIGEN PRESENTING CELLS. They also
ingest and destroy foreign matter coated with ANTIBODIES. Macrophages
can be infected by HIV.
Macrophage Inflammatory Protein-1 Alpha and Beta (MIP-1a,
MIP-1b): CHEMOKINES that bind to the CCR5 RECEPTOR site
and interfere with HIV's fusion with uninfected cells.
Macrophage-Tropic HIV (M-Tropic, CCR5-using HIV, NSI HIV): refers
to strains of HIV that have an affinity for infecting MACROPHAGES
as well as CD4 CELLS. When entering new cells, M-tropic HIV usually
binds to the CCR5 RECEPTOR in addition to the CD4 receptor. This
type of HIV is generally a non-syncytia-inducing (NSI) virus (see
SYNCYTIUM), it is the type of HIV that is transmitted sexually,
and it is generally predominant until late stage disease.
Macula: the pigmented central area or "yellow
spot" of the RETINA that is adjacent to the optic nerve. It
is the most sensitive area of the retina and contains the FOVEA,
a region that is responsible for detailed central vision.
Magnetic Resonance Imaging (MRI): a noninvasive,
non-x-ray diagnostic technique based on the magnetic fields of
hydrogen atoms in the body. MRI provides computer-generated images
of the body's internal tissues and organs.
MAI (Mycobacterium Intercellulare): see MYCOBACTERIUM
AVIUM COMPLEX.
Maintenance Therapy: extended drug therapy, usually
at a diminished dose, administered after a disease has been brought
under control. Maintenance therapy is utilized when a complete
cure is not attainable, and a disease is likely to recur if therapy
is halted. It is used for CHRONIC infections and tumors. So far,
attempts at using maintenance therapy for HIV have been unsuccessful.
See also INDUCTION THERAPY.
Major Histocompatibility Complex (MHC): two classes
of molecules on cell surfaces. MHC class I molecules exist on all
cells and hold and present foreign ANTIGENS to CD8 CYTOTOXIC T
LYMPHOCYTES if the cell is infected by a VIRUS or other MICROBE.
MHC class II molecules are found on the IMMUNE SYSTEM's ANTIGEN
PRESENTING CELLS and display antigen to activate CD4 CELLS.
Malabsorption: inability of the GASTROINTESTINAL
TRACT to absorb food, drugs or any substance needed to maintain
good health; if not countered, leads to weight loss and AIDS WASTING
SYNDROME.
Malaise: a vague feeling of discomfort or uneasiness,
often the result of infection or a drug's SIDE EFFECTS.
Malignant: refers to cells or tumors growing
in an uncontrolled fashion. Such growths may spread to and disrupt
nearby normal tissue or reach distant sites via the bloodstream.
By definition, cancers are always malignant, and the term malignancy
implies cancer.
Manifestation: the outward sign that an illness
is present; a symptom or condition.
MAP-30: see BITTER MELON.
Marinol (Dronabinol): an appetite stimulant composed
of TETRAHYDROCANNABINOL (THC), the major psychoactive ingredient
in marijuana (see CANNABIS).
Masked: see BLINDED.
Mast Cell: an IMMUNE SYSTEM cell filled with
granules of inflammatory chemicals such as histamine. This cell
is believed to play a leading role in generating the symptoms of
allergy.
MDR-TB: see MULTI-DRUG RESISTANT TUBERCULOSIS.
"Me Too" Drug: an informal term used
to describe a drug that offers little or no benefit over a similar
drug that has already been approved by the FDA.
Mean: see AVERAGE.
Median: the midpoint in a series of numbers;
half the data values are above the median, and half are below.
For example, in the odd series 1, 4, 9, 12 and 33, 9 is the median.
In the even series 1, 4, 10, 12, 33 and 88, 11 is the median (halfway
between 9 and 12). Note, the median is not necessarily the same
as the AVERAGE (or mean). For example, the median of 2, 6, 10,
22 and 40 is 10 but the average is 18.
Medulla: the inner portion of an organ.
Megace: see MEGESTROL ACETATE.
Megadosing: medical treatment with very large
doses of a naturally occurring, supposedly nontoxic substance,
usually a VITAMIN.
Mega-HAART: the use of six or more ANTIRETROVIRALS
to treat HIV, typically some or all of which have been used previously
by the individual.
Megestrol Acetate (Megace): an appetite stimulant
approved for the treatment of weight loss in people with AIDS.
Megestrol acetate is a synthetic version of the female hormone
PROGESTERONE. Most of the weight gain it leads to has been found
to be fat rather than PROTEIN. Possible SIDE EFFECTS include HYPERGLYCEMIA,
occasional impotence and decreased LIBIDO in men and uterine bleeding
in women.
Memory T Cell: a T CELL that bears RECEPTORS
for a specific foreign ANTIGEN encountered during a prior infection
or vaccination. After an infection or a vaccination, some of the
T cells that participated in the response remain as memory T cells,
and can rapidly mobilize and clone themselves should the same antigen
be re-encountered during a subsequent infection.
Men Who Have Sex with Men (MSM): a term created
to include MSM who do not identify as gay or bisexual.
Meninges: the membranes that envelope the brain
and the spinal cord.
Meningitis: INFLAMMATION of the MENINGES. It
may be caused by a BACTERIUM, FUNGUS or VIRUS.
Mepron: see ATOVAQUONE.
Meta-Analysis: a method of summarizing previous
research by reviewing and combining results from multiple CLINICAL
TRIALS. Meta-analyses are attempted when previous studies were
too small individually to achieve meaningful or statistically significant
results. Because combining data from disparate groups is problematic,
meta-analyses usually are considered more suggestive than definitive.
Metabolism: the buildup, breakdown and excretion
of substances, commonly used to refer to the breakdown of food
(or drugs) and its transformation into energy.
Metformin (Glucophage): a drug used to treat
high blood sugar.
Methadone: an oral or INTRAVENOUS OPIATE commonly
used to control symptoms of withdrawal from heroin.
Metronidazole (Flagyl): an ANTIBIOTIC used to
treat a variety of infections.
MHC: see MAJOR HISTOCOMPATIBILITY COMPLEX.
Microbe: a microscopic organism, such as a BACTERIA,
FUNGUS, PROTOZOA or VIRUS.
Microbicide: refers to a range of products, in
cream, gel, film, or suppository form, that would substantially
reduce the transmission of HIV — and possibly other sexually
transmitted infections (STIs) — when applied prior to sex.
Micronutrient: a VITAMIN or mineral that the
body must obtain from outside sources. Micronutrients are essential
to the body in small amounts because they are either components
of ENZYMES or act as coenzymes in managing chemical reactions.
Microsporidiosis: an intestinal infection that
causes diarrhea and wasting in people with HIV. It results from
two different species of microsporidia, a protozoal parasite. Two
common organisms that cause it are Enterocytozoon and Septata.
Among the possible treatments are THALIDOMIDE and ALBENDAZOLE.
MIP-1alpha, MIP-1beta: see MACROPHAGE INFLAMMATORY
PROTEIN-1 ALPHA AND BETA.
Mitochondria: a rod-shaped or oval body in cells
that is the site of energy production by means of OXIDATION. Mitochondrial
function can be interrupted by NUCLEOSIDE ANALOGS (LAMIVUDINE [3TC],
STAVUDINE [D4T]) due to inhibition of gamma INTERFERON and DNA
POLYMERASE, leading to lactic acidosis.
Mitogen: a substance that induces cell division.
Mitosis: the process of cell division.
MM: see MONONEURITIS MULTIPLEX.
Molluscum Contagiosum: a skin
condition caused by a pox virus infection, distinguished by small
dome-shaped papules (bumps) on the face, upper trunk or extremities.
Current treatment is mainly cosmetic. It often involves application
of liquid nitrogen to the papules as a means of excising them.
Monoclonal Antibody: an ANTIBODY produced by
laboratory cultures of a single CELL LINE. The antibodies are all
identical, binding with the same EPITOPE.
Monocyte: a large white blood cell that can leave
the blood vessels and enter body tissue, at which point it becomes
a MACROPHAGE.
Mononeuritis Multiplex (MM): a rare type of NEUROPATHY
that causes patchy areas of movement and asymmetrical sensory abnormalities.
MM tends to occur during the ASYMPTOMATIC, early period of HIV
infection, but a more severe type, attributed to CYTOMEGALOVIRUS
(CMV) infection, has been observed in people with advanced AIDS.
Mononucleosis: an infection caused by the EPSTEIN-BARR
VIRUS (EBV) that leads to an increase in mononuclear LEUKOCYTES.
Mononucleosis can be spread by saliva and is also known as the "kissing
disease" (or simply "mono"). Symptoms include fever,
fatigue, sore throat and swollen LYMPH NODES.
Monotherapy: the use of a single drug or therapy
to treat a disease or condition.
Morbidity: having an illness or disease.
Mortality: death.
MRI: see MAGNETIC RESONANCE IMAGING.
MSM: see MEN WHO HAVE SEX WITH MEN.
M-Tropic: see MACROPHAGE-TROPIC.
Mucous Membrane: the moist layer of tissue lining
the digestive, respiratory, urinary and reproductive tracts - all
the body cavities with openings to the outside world except the
ears.
Multi-Drug Resistant Tuberculosis (MDR-TB): a
strain of TUBERCULOSIS (TB) that does not respond to two or more
standard anti-TB drugs. MDR-TB usually arises when treatment is
intermittent, thus permitting replication and allowing an accumulation
of MUTATIONS in the TB BACTERIA that confer broader and broader
drug RESISTANCE.
Multiple Regression Analysis: a statistical method
used with one dependent variable and more than one independent
variable.
Multivariate Analysis: a statistical analysis
that involves more than one dependent variable.
Murine: of or relating to rodents, especially
mice.
Mutagen: an agent that has a tendency to increase
MUTATIONS.
Mutation: any alteration, loss, gain or exchange
of genetic material within a cell or VIRUS. Mutations are perpetuated
in succeeding generations of that cell or virus (or of an entire
multicellular organism if the mutated cell is a sperm, egg or spore).
They can occur spontaneously or in response to environmental factors,
including drug therapy. See also RESISTANCE.
Myalgia: pain in one or more muscles.
Myambutal: see ETHAMBUTAL.
Mycelex: see CLOTRIMAZOLE.
Mycobacterium: a group of BACTERIA with many
disease-causing members. The causative agents for TUBERCULOSIS,
leprosy and MYCOBACTERIUM AVIUM COMPLEX (MAC) all belong
to this group.
Mycobacterium Avium Complex (MAC): a
serious OPPORTUNISTIC CONDITION caused by two similar BACTERIA
(Mycobacterium avium and Mycobacterium intercellulare)
found in the soil and dust particles. In AIDS, MAC can spread through
the bloodstream to infect LYMPH NODES, BONE MARROW, liver, SPLEEN,
spinal fluid, lungs and intestinal tract. Typical symptoms of MAC
include night sweats, weight loss, fever, fatigue, diarrhea and
enlarged spleen. MAC is usually found in people with CD4 CELL COUNTS
below 95. CLARITHROMYCIN, AZITHROMYCIN, ETHAMBUTAL, RIFAMPIN, clofazimine
and RIFABUTIN are some of the ANTIBIOTICS commonly used in MAC
prevention and treatment. (Treatment of active infection usually
involves combination therapy.)
Mycobacterium Intercellulare (MAI): see MYCOBACTERIUM
AVIUM COMPLEX.
Mycobutin: see RIFABUTIN.
Mycoplasma: a group of BACTERIA, some of whose
members cause disease in animals and humans. Mycoplasma are very
simple one-celled organisms without an outer membrane. They penetrate
and infect individual cells. Most commonly, mycoplasma causes pneumonia.
Mycosis: any disease caused by a FUNGUS.
Myelin: a fatty substance that covers and protects
the nerves.
Myelitis: INFLAMMATION of the spinal cord.
Myelopathy: any disease affecting the spinal
cord.
Myelosuppression: see BONE MARROW SUPPRESSION.
Myelotoxic: destructive to BONE MARROW.
Myocardial: refers to the heart's muscle mass.
Myopathy: progressive muscle weakness. Myopathy
may arise as a toxic reaction to AZT (ZIDOVUDINE) or as a consequence
of HIV infection itself.
N
NAC: see N-ACETYLCYSTEINE.
N-Acetylcysteine (NAC): a naturally occurring
substance that is metabolized into the AMINO ACID CYSTEINE. Cysteine
is one of the three components of the major cellular ANTIOXIDANT
GLUTATHIONE, and people with HIV have decreased levels of this
compound. Taking NAC will restore glutathione levels, but it remains
to be proven whether this increase in glutathione has clinical
benefit. See also OXIDATIVE STRESS.
Nadir: the lowest point.
Naive T Cell: a T CELL arising from the IMMUNE
SYSTEM'S production of fresh cells in the BONE MARROW. Naive T
cells respond to newly encountered PATHOGENS containing ANTIGENS
the immune system has not processed before. The naive T cells'
activation and proliferation create an acquired immune response
(see IMMUNE SYSTEM) to the newly encountered pathogenic agent.
After the disease is eradicated, a portion of the T cell population
engendered by the activated naive T cells constitute a reservoir
of memory cells, which proliferate and respond very quickly to
any recurrence of the disease. See also MEMORY T CELL.
Nandralone Decanoate (Deca Durabolin): an injectable
synthetic ANABOLIC STEROID being studied for the treatment of AIDS-related
WASTING SYNDROME.
NASBA: see NUCLEIC ACID SEQUENCE-BASED AMPLIFICATION.
National Cancer Institute (NCI): a branch of
the NATIONAL INSTITUTES OF HEALTH (NIH) that oversees considerable
research in HIV and AIDS-related malignancies.
National Institute of Allergy and Infectious Diseases
(NIAID): the federal agency that is responsible for
a great deal of the government-sponsored AIDS research. NIAID
is a branch of the NATIONAL INSTITUTES OF HEALTH (NIH).
National Institute of Mental Health (NIMH): a
branch of the NATIONAL INSTITUTES OF HEALTH (NIH) that oversees
neurologic and psychologic research.
National Institutes of Health (NIH): the federal
agency responsible for overseeing government-sponsored biomedical
research. It is divided into 24 institutes and research centers.
Natural History of Disease: the course of a disease
when left untreated.
Natural History Study: a study that observes
the development of a disease over time.
Natural Killer (NK) Cell: a type of LYMPHOCYTE
that attacks and destroys foreign, VIRUS-infected and cancerous
cells. NK cells are not targeted at specific ANTIGENS the way CYTOTOXIC
T LYMPHOCYTES are. They are part of the innate rather than the
acquired immune response (see IMMUNE SYSTEM).
NC = F: see NONCOMPLETER EQUALS FAILURE.
NCI: see NATIONAL CANCER INSTITUTE.
NDA: see NEW DRUG APPLICATION.
NebuPent: see PENTAMIDINE.
Nef: an HIV regulatory PROTEIN. HIV without nef
appears to have lessened capacity to infect new cells. Nef also
blocks HIV-infected cells from expressing CD4 and MAJOR HISTOCOMPATIBILITY
COMPLEX (MHC) class I molecules on their surfaces, thus limiting
the IMMUNE SYSTEM's ability to recognize and kill these cells.
Nelfinavir (Viracept): a PROTEASE INHIBITOR from
Agouron / Pfizer, FDA-approved for adults and children over two
years old. Nelfinavir should be taken two or three times a day
with a meal or light snack. Its most common SIDE EFFECT is diarrhea.
Nelfinavir can reduce blood levels of oral contraceptives and increase
blood levels of other protease inhibitors.
Neonate: a newborn, typically up to four weeks
of age.
Neoplasia: the abnormal growth of new tissue,
consisting of a NEOPLASM or tumor.
Neoplasm: literally, a new growth. An abnormal
growth of tissue, a tumor.
Neopterin: a substance present in BODILY FLUIDS
that is elevated when the IMMUNE SYSTEM is activated. SERUM or
CEREBROSPINAL FLUID neopterin levels were measured in early studies
as a SURROGATE MARKER for HIV disease.
Nephritis: INFLAMMATION of the kidneys.
Nephrolithiasis: the formation of sediment or
small stones in the kidneys. See also KIDNEY STONE.
Nephrotoxicity: damage to the kidneys.
Nerve Growth Factor (NGF): a naturally produced
substance that has many roles in the maintenance of nerves and
nerve cells, especially sensory ones. Synthetic, RECOMBINANT NGF
is a proposed therapy for HIV- and drug-associated NEUROPATHIES.
Neupogen: see GRANULOCYTE COLONY STIMULATING
FACTOR.
Neurologic: relating to the nervous system, including
the brain.
Neuron: one of the electrically active cells
that transmit signals within the brain or nervous system.
Neuropathy: disease or INFLAMMATION and degeneration
of the nerves. See PERIPHERAL NEUROPATHY.
Neuropsychologic Tests: tests designed to measure
certain aspects of brain function, such as memory, concentration,
attention and visual/motor skills.
Neurotransmitter: a substance secreted by excited
nerve cells (NEURONS) that conveys the nerve signal to another
nerve cell across the gap, or synapse, between the two cells.
Neutralizing Antibody: ANTIBODIES that can directly
block the infective capacity of a microorganism, particularly a
VIRUS' ability to penetrate cells.
Neutrexin: see TRIMETREXATE.
Neutropenia: a shortage of NEUTROPHILS in the
blood.
Neutrophil: a type of GRANULOCYTE that is especially
protective against bacterial and fungal infections. Neutrophils
are also called polymorphonuclear cells (PMNs) because of their
internal structure.
Nevirapine (Viramune): Boehringer Ingelheim's
NON-NUCLEOSIDE REVERSE TRANSCRIPTASE INHIBITOR (NNRTI). Nevirapine
is FDA-approved for treatment of HIV-infected adults in combination
with NUCLEOSIDE ANALOGS. Possible SIDE EFFECTS include severe rash,
fever and liver impairment. Nevirapine interacts with many other
drugs.
New Drug Application (NDA): an application to
the FDA asking for approval to market a new drug.
NGF: see NERVE GROWTH FACTOR.
NHL: see NON-HODGKIN'S LYMPHOMA.
NIAID: see NATIONAL INSTITUTE OF ALLERGY AND
INFECTIOUS DISEASES.
NIH: see NATIONAL INSTITUTES OF HEALTH.
NIMH: see NATIONAL INSTITUTE OF MENTAL HEALTH.
Nizoral: see KETOCONAZOLE.
NK Cell: see NATURAL KILLER CELL.
NNRTI: see NON-NUCLEOSIDE REVERSE TRANSCRIPTASE
INHIBITOR.
Noncompleter Equals Failure (NC=F): the most
conservative type of analysis in which participants who drop out
of a CLINICAL TRIAL are considered to have failed therapy.
Noncompliant: refers to a patient who is unwilling
or unable to follow a treatment REGIMEN as prescribed.
Non-Hodgkin's Lymphoma (NHL): a LYMPHOMA made
up of B CELLS and characterized by nodular or diffuse tumors that
may appear in the stomach, liver, brain or BONE MARROW. After KAPOSI'S
SARCOMA, NHL is the most common opportunistic cancer in people
with AIDS.
Non-Nucleoside Reverse Transcriptase Inhibitor (NNRTI): a
member of a class of compounds, including DELAVIRDINE, NEVIRAPINE
and EFAVIRENZ, that acts to directly combine with and block the
action of HIV's REVERSE TRANSCRIPTASE enzyme. In contrast, NUCLEOSIDE
ANALOGS block reverse transcriptase by capping the unfinished DNA
chain that the ENZYME is constructing.
Nonoxynol-9: an anti-microbial agent present
in some spermicides and lubricants. Nonoxynol-9 has been shown
to irritate mucosal linings, which may possibly facilitate HIV
infection and its use is not recommended as an MICROBICIDE.
Non-Syncytium-Inducing HIV: see SYNCYTIUM; T-TROPIC
HIV.
Norvir: see RITONAVIR.
NRTI: see NUCLEOSIDE ANALOG.
NSI Virus (Non-Syncytium-Inducing HIV): see SYNCYTIUM;
T-TROPIC HIV.
NtRTI: see NUCLEOTIDE ANALOG.
Nucleic Acid Sequence-Based Amplification (NASBA): an
ASSAY used to detect HIV VIRAL LOAD in blood PLASMA.
Nucleoside: a combination of one of five single
or double ringed "bases" and a sugar (ribose for RNA
or deoxyribose for DNA). These molecular units are the building
blocks of DNA and RNA, the genetic material found in living organisms.
Before being added to a DNA or RNA sequence, nucleosides must have
a phosphate group added (see PHOSPHORYLATION).
Nucleoside Analog (Nucleoside Analog Reverse Transcriptase
Inhibitor, NRTI): a type of ANTIVIRAL drug, such as
AZT (ZIDOVUDINE), ddI (DIDANOSINE), ddC (DIDEOXYCYTIDINE) or
d4T (STAVUDINE), whose structure constitutes a defective version
of a natural NUCLEOSIDE. Nucleoside analogs may take the place
of the natural nucleosides, blocking the completion of a viral
DNA chain during infection of a new cell by HIV. The HIV enzyme
REVERSE TRANSCRIPTASE is more likely to incorporate nucleoside
analogs into the DNA it is constructing than is the DNA POLYMERASE
that cells normally use for DNA construction.
Nucleoside Analog Reverse Transcriptase Inhibitor: see
NUCLEOSIDE ANALOG.
Nucleotide: a building block of RNA and DNA that
consists of a base, a sugar, and a phosphate group. A phosphorylated
nucleoside (see NUCLEOSIDE and PHOSPHORYLATION).
Nucleotide Analog: TENOFOVIR, ADEFOVIR, CIDOFOVIR
and other ANTIVIRAL compounds that function exactly like NUCLEOSIDE
ANALOGS but are pre-activated through the addition of a phosphate
group during their synthesis. This PHOSPHORYLATION is supposed
to enhance the drug levels and activity achieved within cells.
Nucleotide analogs typically are active against a wide range of
VIRUSES, including HERPES VIRUSES, HEPATITIS B and sometimes HIV.
Nystatin: an antifungal drug used primarily as
a topical agent for oral CANDIDIASIS (THRUSH).
O
Observational Study: a study that does not involve
randomization but where available data are nonetheless analyzed
to make treatment comparisons. Observational studies are subject
to bias, which may render their conclusions less reliable than
those obtained by well controlled randomized CLINICAL TRIALS. Still,
they may be useful for hypothesis generation and defining the natural
history of disease.
Octoxynol: a chemical used in spermicides.
Octreotide Acetate (Sandostatin): an antidiarrheal
drug.
Ocular: relating to the eye.
Odynophagia: pain when swallowing.
Off-Label: use of a drug for a disease or condition
other than the INDICATION for which it was approved by the FDA.
For example, many doctors prescribe PAROMOMYCIN for CRYPTOSPORIDIOSIS,
although it is not approved for treating this disease.
OHL: see ORAL HAIRY LEUKOPLAKIA.
OI (Opportunistic Infection): see OPPORTUNISTIC
CONDITION.
Oocysts: the first stage in the life cycle of
a parasitic PROTOZOAN.
Open-Label Trial: a study in which both researchers
and participants know what drugs a person is taking and at what
dose. Compare BLINDED.
Opiate: a natural or synthetic derivative of
opium that has similar ANALGESIC and sedative effects.
Opportunistic Condition: an infection or cancer
that occurs especially or exclusively in persons with weak IMMUNE
SYSTEMS due to AIDS, cancer or immunosuppressive drugs such as
CORTICOSTEROIDS or CHEMOTHERAPY. KAPOSI'S SARCOMA (KS), PNEUMOCYSTIS
CARINII PNEUMONIA (PCP), TOXOPLASMOSIS and CYTOMEGALOVIRUS
are all examples of opportunistic conditions. Also more loosely
termed "opportunistic infection"(OI).
Oral Candidiasis: see THRUSH.
Oral Hairy Leukoplakia (OHL): a white lesion
that appears on the side of the tongue and inside cheeks. The lesion
appears raised, with a ribbed or "hairy" surface. OHL
occurs mainly in people with declining immunity and may be caused
by EPSTEIN-BARR VIRUS infection.
Organic Molecule: a molecule that comes, or came,
from a living thing.
Orphan Drug: a status granted by the FDA to unpatentable
medications developed for rare diseases. Orphan drug status gives
the drug's manufacturer a seven-year right to exclusively market
the compound. This protection of unpatentable orphan drugs encourages
their development by greatly increasing their profitability.
Osteoporosis: loss of bone density due to depletion
of calcium and bone PROTEIN.
Oxandrin: see OXANDROLONE.
Oxandrolone (Oxandrin): an oral ANABOLIC STEROID
approved by the FDA in 1962 as a general remedy for weight loss
in a variety of conditions including CHRONIC infection. Now being
studied as treatment for AIDS-related WASTING SYNDROME.
Oxidation: a chemical reaction resulting from
exposure to oxygen or other electron-seizing atoms or molecular
combination of atoms (see FREE RADICALS). On the cellular level,
oxidative reactions are the source of energy, but free radicals
and other oxidizing agents can damage cellular components, such
as membranes, and interfere with cells' regulatory systems.
Oxidative Stress: a highly oxidized environment
within cells that is thought to promote HIV replication because
cells are forced into a highly activated state due to loss of control
of their regulatory systems.
Oxymetholone (Anadrol): an anabolic-androgenic
STEROID used to treat ANEMIA.
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