Glossary
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A
ABSCESS: an isolated accumulation of pus associated
with a localized infection. Abscesses may result in tissue destruction,
pain, and swelling; severe abscesses may require surgical drainage.
ADHERENCE: following a prescribed treatment regimen, including correct
dosage, number of doses per day, and dietary restrictions.
AMYLASE: an enzyme produced by the salivary glands and the pancreas
that helps break down food. An abnormal increase in serum amylase levels
may indicate
inflammation of the pancreas (pancreatitis).
ANAL INTRAEPITHELIAL NEOPLASIA (AIN): the abnormal growth of cells of
the anus, which may be a precursor of anal cancer.
ANTIBODY (AB, IMMUNOGLOBULIN, IG):
an immunoglobulin protein secreted by activated plasma cells, which
evolve from B-cells. Antibodies are present throughout the blood and
tissues; they are produced in response to stimulation by foreign antigens
as part of the body's defense against disease. Specific antibodies bind
to and act upon specific antigens; the antigen/antibody reaction forms
the basis of humoral (TH2) immunity. Neutralizing antibodies destroy
or inactivate infectious agents, while enhancing antibodies promote
infection.
ANTIRETROVIRAL: an agent (e.g., AZT, ddI, or nevirapine) that suppresses
the activity or replication of retroviruses such as HIV.
B
BETA BLOCKER DRUGS: one
of a large group of medications that obstruct specific nervous system
receptors, causing a deceleration of the heart rate, a reduction in
blood pressure, and reduced anxiety. Beta blockers are used to treat
high blood pressure, angina, and other conditions.
BILIRUBIN: a pigment produced
when the liver processes waste products. A high bilirubin level causes
yellowing of the skin.
BLOOD-BRAIN BARRIER: a physical
barrier between the blood vessels and the brain that is selectively
permeable, i.e., allows only certain substances to pass through.
BRANCHED-CHAIN DNA ASSAY
(bDNA, QUANTIPLEX HIV RNA ASSAY): a test that measures the amount of
virus (viral load) in plasma or tissue using a chemical signal, visible
as light, that is produced by viral RNA.
BREAKTHROUGH: a condition
that develops despite measures to prevent it (e.g., PCP that occurs
while taking a prophylactic drug). Also, a rise in viral load after
it has fallen due to anti-HIV therapy (virological breakthrough).
BUFFALO HUMP: dorsocervical
(or cervicodorsal) fat pad; an accumulation of fatty tissue on the upper
back at the base of the neck.
C
CARDIOVASCULAR: refers to
the circulatory system (the heart and blood vessels).
CD4 CELL (CD4 LYMPHOCYTE,
T-HELPER CELL, T4 CELL): a type of white blood cell that carries the
CD4 cell surface receptor and helps the body fight infection. CD4 cells
release cytokines (chemical messengers) that coordinate a broad range
of immune system activities including killer cell activation and antibody
production.
CD4 CELL COUNT (T-HELPER
CELL COUNT): the absolute number of CD4 lymphocytes in one cubic millimeter
(mm3) of blood. The CD4 cell count is one indicator of the progression
of HIV disease.
CERVICODORSAL FAT PAD: see
buffalo hump.
CHRONIC: less intense, slow,
persisting over a long period. Contrast with acute.
COCCIDIOIDOMYCOSIS (VALLEY
FEVER): a fungal disease acquired by inhaling dust particles containing
spores of Coccidioides immitis. The disease affects the upper respiratory
tract and lungs, and may sometimes disseminate to visceral organs, bones,
skin, and other tissues. Symptoms include cough, fatigue, fever, and
weight loss.
COHORT: a group of individuals
in a study who share a demographic, clinical, or other statistical characteristic
(e.g., age or study site).
CROSS-RESISTANCE: the development
of resistance to one agent (e.g., a drug) that also confers resistance
to another agent (e.g., a similar drug of the same class).
CRYPTOSPORIDIOSIS: a disease
caused by the protozoan Cryptosporidium parvum, which is transmitted
by contact with animal feces, ingestion of contaminated food or water,
or oral-anal sexual contact (rimming). It can cause severe, chronic
diarrhea, weight loss, and lymphadenopathy.
CYTOKINE: an intercellular
hormone or chemical messenger protein (e.g., tumor necrosis factor,
interleukin) released by white blood cells (e.g., macrophages, T cells).
Cytokines facilitate communication among immune system cells and between
immune system cells and the rest of the body.
CYTOMEGALOVIRUS (CMV, HUMAN
HERPESVIRUS 5): a herpesvirus. CMV infection often occurs in healthy
individuals without causing symptoms. In immunocompromised individuals
(usually with CD4 cell counts below 50 cells/mm3), CMV may cause serious
illness including retinitis (inflammation of the retina), pneumonia,
colitis (inflammation of the large bowel), and encephalitis. CMV may
be treated with ganciclovir, foscarnet, or cidofovir.
D
DNA (DEOXYRIBONUCLEIC
ACID): a molecule that encodes genetic information and is found in the
nucleus of cells as a twisted double-stranded chain. The particular sequence
of four chemical building blocks (nucleotides) adenine, cytosine, guanine,
and thymine—that make up a DNA chain determines the unique genetic code
of an individual.
E
ELECTROLYTE: an electrically
charged element or compound (e.g., sodium, potassium) found in body
fluids, tissues, and cells. An imbalance of electrolytes can result
from prolonged vomiting or diarrhea, and may lead to the disruption
of many bodily processes, possibly resulting in muscle weakness, cramps,
or seizures.
EPIDEMIOLOGY: the study
of the frequency, distribution, and behavior of a disease within a population.
EPSTEIN-BARR VIRUS (EBV,
HUMAN HERPESVIRUS 4):a herpesvirus. EBV infection is common and usually
asymptomatic in children, but may cause infectious mononucleosis in
young adults. It is associated with oral hairy leukoplakia, lymphoid
interstitial pneumonitis, and some types of cancer in people with HIV
disease.
ESTRADIOL: a potent form
of estrogen produced by the ovaries, placenta, and testes.
ESTROGEN: a female sex hormone;
a natural or synthetic substance (e.g., estradiol, Premarin) that stimulates
the development of female secondary sex characteristics and regulates
the reproductive cycle in women. Estrogens are known to affect the immune
system.
ETHINYL ESTRADIOL: a semisynthetic
estrogen often used in oral contraceptives.
F
FOLLICLE STIMULATING HORMONE
(FSH): in women, follicle stimulating hormone stimulates the development
of ovarian follicles (eggs) and stimulates the release of estrogens.
FOLLICULAR PHASE: the preovulatory
phase of a woman’s reproductive cycle during which the follicle grows
and high estrogen levels cause the uterine lining to grow.
G
GASTROINTESTINAL: pertaining
to the stomach and intestines.
GENE (adjective GENETIC):
the unit of heredity. A gene contains hereditary information encoded
in the form of DNA and is located at a specific position on a chromosome
in a cell’s nucleus.
GLUCOCORTICOID: a steroid-like
substance (e.g., cortisol) capable of influencing metabolism, regulating
the immune system, and exerting an anti-inflammatory effect.
GLUCOSE (BLOOD SUGAR): a
form of sugar that is the body’s primary fuel; glucose broken down from
food can be converted into energy or stored. Abnormally low or high
levels of glucose in the blood often indicate metabolic disturbances
(e.g., diabetes).
H
HABITUS: physical or constitutional
characteristics.
HALF-LIFE: the time required
for half the amount of an agent (e.g., drug, virus, cell type) to be
eliminated from the body.
HEMOGLOBIN (Hb): the red,
iron-based pigment in red blood cells that enables them to transport
oxygen.
HEPATITIS: an inflammation
of the liver that may be caused by several agents, including viruses,
toxins, or drugs. Acute hepatitis is typically characterized by fever,
jaundice, fatigue, abdominal tenderness, and elevated liver enzymes.
Hepatitis A virus (HAV) causes an inflammatory viral disease with a
short incubation period. Hepatitis B and C can become chronic and may
result in liver damage, cirrhosis, or liver cancer. There are also hepatitis
viruses D, E, F, and G.
HISTOPLASMOSIS: a fungal
infection acquired by inhaling spores of the fungus Histoplasma capsulatum,
which are present in soil or dust. The disease most often affects the
lungs, where it produces a tuberculosis-like inflammation, but may also
disseminate. Symptoms include cough, fever, and weight loss. The disease
may be life-threatening in indiviuals with suppressed immune systems.
HORMONE: a chemical messenger
(e.g., adrenaline, testosterone) involved in the regulation and coordination
of cellular and bodily functions.
HUMAN PAPILLOMAVIRUS (HPV):
a papovavirus, many strains of which cause warts, including condylomata
acuminata (genital warts). Certain strains of HPV (e.g., 16, 18) are
associated with cervical, anal, and oral cancer.
HYPERMENORRHEA: unusually
frequent or heavy menstrual bleeding.
I
INTENT-TO-TREAT ANALYSIS:
analysis that requires the inclusion of all randomized subjects, regardless
of whether they remain on protocol for the duration of the study.
INTERMITTENT: occurring
sporadically or in phases.
K
KAPOSI’S SARCOMA
(KS): an abnormal or cancerous proliferation of cells of the blood and/or
lymph vessels causing tumors on the skin, mucous membranes, and/or internal
organs. KS typically appears as purplish or brownish lesions, and is
associated with a herpesvirus (KSHV, or HHV-8).
L
LEUTENIZING HORMONE (LH):
a hormone produced by the pituitary gland that acts with FSH (follicle
stimulating hormone) to stimulate ovulation, and androgen and progesterone
secretion.
LIPID: a fat.
LIPODYSTROPHY: a loss of
fatty tissue, usually in the limbs and face. The term is sometimes used
to refer to any type of body fat redistribution.
LIPOPROTEIN: a compound
composed of protein and fats.
LUTEAL PHASE: the postovulatory
phase of a woman’s menstrual cycle. See also ovulation..
M
MATERNAL-FETAL BARRIER:
the placental barrier. See placenta.
MEAN: a statistical measurement
of the central tendency, or average, of a set of values. Contrast with
median.
MEDIAN: the number within
a series that is preceded and followed by an equal number of values.
Contrast with mean.
MENSTRUAL CYCLE: the reproductive
cycle of female humans characterized by a monthly discharge of blood,
mucus, and tissues from the uterus. This cycle involves changes to the
uterine wall during the rest of the month including a few days of fertility
after an ovum (egg) is released from an ovary.
MOLECULE: a small unit of
matter made up of atoms. A molecule is the smallest unit of a substance
that retains its unique characteristics.
MONONUCLEOSIS (KISSING DISEASE):
an infectious disease caused by the Epstein-Barr virus that is easily
transmitted via saliva. The disease is characterized by a sore throat,
fatigue, and possibly swollen lymph nodes or a swollen spleen.
MUTATION: a change in the
character of a gene that is perpetuated when a cell divides or a virus
replicates. A mutant is a new strain of an organism produced by a genetic
mutation.
MYCOBACTERIUM AVIUM
COMPLEX (MAC): an opportunistic disease caused by Mycobacterium avium
or Mycobacterium intracellulare (sometimes referred to as
Mycobacterium avium-intracellulare or MAI), bacteria found in
soil and water. In immunosuppressed persons, the bacteria can infect
the lymph nodes, intestines, bone marrow, liver, spleen, spinal fluid,
lungs, and the gastrointestinal tract, and may become disseminated.
MAC is the most common bacterial infection in persons with advanced
AIDS (usually with CD4 cell counts below 5075 cells/mm3). Symptoms include
diarrhea, wasting, fever, night sweats, fatigue, and spleen enlargement.
Clarithromycin is used as treatment and prophylaxis for MAC.
N
NNRTI: see non-nucleoside
reverse transcriptase inhibitor.
NON-NUCLEOSIDE REVERSE TRANSCRIPTASE
INHIBITOR (NNRTI): a drug (e.g., nevirapine, delavirdine, efavirenz)
that binds with and inhibits the action of the HIV reverse transcriptase
enzyme, thus blocking viral transcription and replication.
NORETHINDRONE:a synthetic
hormone with actions similar to progesterone but functioning as a more
potent inhibitor of ovulation.
NRTI: see nucleoside
reverse transcriptase inhibitor.
NUCLEOSIDE ANALOG: see nucleoside
reverse transcriptase inhibitor.
NUCLEOSIDE REVERSE TRANSCRIPTASE
INHIBITOR (NRTI, also known as NUCLEOSIDE ANALOG): a compound
(e.g., AZT, ddI, ddC, d4T, 3TC) that mimics one of the building blocks
of DNA. These compounds suppress retroviral replication by interfering
with the reverse transcriptase enzyme.
O
OPPORTUNISTIC INFECTION
(OI): a disease caused by a microorganism that does not normally cause
illness in a person with a healthy immune system, but that may cause
serious disease when the immune system is weakened. Common OIs in HIV
positive people include Pneumocystis carinii pneumonia (PCP),
Mycobacterium avium complex (MAC), and cytomegalovirus (CMV)
infection.
OVARY: one of the two female
gonads located within the abdomen on either side of the uterus. The
ovaries are the site of egg (ovum) storage and maturation.
OVULATION: the process by
which an ovum (egg) is discharged from an ovary.
P
PAPANICOLAOU SMEAR (PAP
SMEAR): a procedure in which a specimen of cells is taken from the uterine
cervix or anus, prepared on a slide, and examined under a microscope
for abnormal cell growth. An abnormal Pap smear suggests increased risk
of developing cancer.
P-GLYCOPROTEIN: a family
of plasma membrane proteins which, when overexpressed, can cause multidrug
resistance.
PHARMACOLOGICAL: See pharmacology.
PHARMACOLOGY: the science
of drugs, their sources, and how they work.
PLACENTA: the organ that
connects the fetus and the mother’s uterus and enables the exchange
of oxygen and nutrients.
PNEUMOCYSTIS CARINII
PNEUMONIA (PCP): a life-threatening opportunistic type of pneumonia
believed to be caused by a protozoan. PCP is a common infection that
can cause severe illness in immunocompromised people (especially those
with CD4 cell counts of fewer than 200 cells/mm3); it remains a leading
cause of death in people with AIDS. Symptoms include dry cough, fever,
chest tightness, and shortness of breath. Pneumocystis carinii
can also infect other parts of the body. First-line treatment and primary
prophylaxis is TMP-SMX (Bactrim, Septra); other treatments and prophylaxes
include dapsone, pentamidine, and atovaquone.
POLYMERASE CHAIN REACTION
(PCR) ASSAY: a highly sensitive test that can detect small amounts of
DNA or RNA (genetic material) in a blood or tissue sample using an amplification
technique that multiplies the existing DNA/RNA so that it can more easily
be detected. PCR assays are used to determine viral loads in persons
infected with HIV.
PRODRUG: an inactive form
of a drug that exerts its effects after metabolic processes within the
body convert it to a usable or active form.
PROGESTIN: a hormone produced
by the corpus luteum, placenta, or adrenal cortex (or synthetically
manufactured) that has progesterone-like effects. Synthetic progestin
is used as a contraceptive.
PROLACTIN: a pituitary hormone
that stimulates the secretion of breast milk.
PROPHYLAXIS (PX): therapy
that helps to prevent a disease or condition before it occurs (primary
prophylaxis) or recurs (secondary prophylaxis).
PROTEASE INHIBITOR (PI):
a drug (e.g., saquinavir, ritonavir, indinavir, nelfinavir, amprenavir)
that blocks the action of the HIV protease enzyme, thereby preventing
viral replication. Unlike reverse transcriptase inhibitors, protease
inhibitors can inhibit HIV replication in cells that are already infected.
PSYCHOSTIMULANT: a drug
that causes increased responsiveness of the mind.
R
RESISTANCE: the mutation
of a microorganism in such a way that it loses its sensitivity to a
drug; a resistant organism can function and replicate despite the drug’s
presence. Contrast with susceptible. Genotypic and phenotypic resistance
tests are used to measure whether an organism is resistant to a drug.
See also cross-resistance.
RIBONUCLEIC ACID (RNA):
a single-stranded nucleic acid that encodes genetic information. RNA
takes the place of DNA in retroviruses such as HIV. The presence of
HIV RNA in the plasma indicates that the virus is actively replicating.
RNA: see ribonucleic
acid.
S
SEROCONVERSION: the development
of antibodies directed against an antigen; the change in a person’s
antibody status from negative to positive. Vaccine-induced seroconversion
is not an infection.
SERONEGATIVE: having a blood
test that does not indicate infection with a microorganism (e.g., HIV),
either by the presence of antibodies or antigens.
SEROPOSITIVE: having a blood
test result that indicates infection with a microorganism (e.g., HIV).
A test may detect either antibodies to an organism (antibody positive)
or the organism or its proteins (antigen positive).
SUBCUTANEOUS: beneath the
skin; subdermal.
SURROGATE MARKER: a marker
or sign that can serve in place of a clinical endpoint such as disease
progression or death. Surrogate markers for HIV disease may be virologic
(e.g., viral load), immunologic (e.g., CD4 cell count), or clinical
(e.g., weight loss).
SUSCEPTIBLE: vulnerable
to or potentially able to contract a disease. Also refers to a microorganism
that is vulnerable to the effects of a drug. Contrast with resistance.
SYMPTOMATIC: showing outward
signs of a disease.
SYNERGY (SYNERGISM, adjective
SYNERGISTIC): an interaction between agents (e.g., drugs) that produces
an effect greater than the combined effects of the same agents used
separately.
T
TESTOSTERONE: a steroid
hormone produced by the testes and adrenal glands. Testosterone is required
for sperm production, the development of the male reproductive organs,
and the emergence of male secondary sexual characteristics. The hormone
is also required for the buildup of lean muscle mass.
THYROID GLAND: an organ
at base of the neck that produces thyroxin and other hormones.
TOXICITY (adjective
TOXIC): the quality of being poisonous or harmful; often used to refer
to side effects of drugs.
TOXOPLASMOSIS: an opportunistic
infection caused by the microscopic protozoan Toxoplasma gondii,
found in undercooked meat and cat feces. Symptoms may include headache,
lymphadenopathy, malaise, muscle pain, and fever. A common manifestation
of the disease is toxoplasmic encephalitis (cerebral toxoplasmosis),
characterized by brain swelling, confusion, lethargy, seizures, and
coma; the eyes, heart, and lungs may also be affected. Toxoplasmosis
is treated with pyramethamine, usually in combination with other drugs;
TMP-SMX may be used as prophylaxis.
TRIGLYCERIDE: a combination
of glycerol and fatty acid that circulates in the blood.
TUBERCULOSIS (TB): an infectious
disease caused by Mycobacterium tuberculosis that typically affects
the lungs (pulmonary TB), but may also occur in other organs (extrapulmonary
TB). Transmission generally occurs through inhalation of aerosolized
sputum droplets. A combination of four chemotherapeutic drugs is standard
therapy. Multidrug-resistant tuberculosis (MDRTB) is resistant to several
standard drugs and requires more aggressive treatment.
TUMOR NECROSIS FACTOR (TNF,
CACHECTIN): a cytokine (chemical messenger) that can destroy tumors.
When chronically elevated, as may occur in HIV disease, TNF-alpha (one
type of TNF) may lead to fever, anorexia, hypermetabolism, and wasting.
TNF-alpha may block the production of enzymes that digest fats, leading
to the breakdown of muscle tissue. In laboratory tests TNF-alpha has
been shown to stimulate HIV replication.
V
VIRAL BREAKTHROUGH: see
breakthrough.
VIRAL LOAD (VIRAL BURDEN):
the amount of virus in the blood or body tissues. The presence of HIV
RNA indicates that the virus is replicating. Changes in viral load may
be used to gauge drug effectiveness and disease progression. Viral load
is measured using tests such as polymerase chain reaction (PCR) or branched-chain
DNA (bDNA), and is typically expressed as the number of copies of RNA
per milliliter (mL) of blood plasma.
VIRAL REPLICATION: multiplication
or reproduction of a virus in a person’s blood.
VIRAL SUPPRESSION: the cessation
of detectable viral replication in a person’s blood.
VIREMIA: the presence of
virus in the blood.
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last updated 30 May 2001
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