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CENTRAL GLOSSARY

Adaptive immune response: Second line of the immune response spleen. B­lymphocytes produce antibodies. In people with that is specific to a given foreign molecule or pathogen and HIV, the ability of B­lymphocytes to do their job may be leads to an “immunological memory” after the first response damaged. to the molecule or pathogen. Bacteremia: The presence of viable bacteria in the blood. Additive: The effect when two or more agents act together to Bronchiectasis: Disease of the airways characterized by a local­ achieve a result that is the sum of the effects achieved by the ized, irreversible widening (dilation) of a part of the airways; individual agents. the affected bronchi and bronchioles are dilated, inflamed AIDS­defining illness or event: Any one of a group of illnesses and collapse easily, resulting in reduced airflow; usually presence of which indicates that a patient’s HIV infection caused by bacterial infections. has progressed to the acquired immune deficiency syndrome Basal ganglia: A group of nuclei in the interconnected (AIDS); these conditions include, among others, yeast infections with the , thalamus and brainstem. Mammalian of the airways (i.e., candidiasis), Kaposi’s sarcoma, certain basal ganglia are associated with a variety of functions: viral infections, tuberculosis, and certain cancers. motor control, cognition, emotions, and learning. Airway obstruction: Respiratory problem in which the small

airways (bronchioles) show increased resistance, thereby Cachexia: A syndrome characterized by weight loss, muscle reducing the amount of air inhaled in each breath and, atrophy, fatigue, weakness, and loss of appetite that cannot consequently, the amount of oxygen that can be taken up be reversed by increased nutrition. into the body. Cardiovascular disease: Generic term for diseases that involve Alveolus (pl. alveoli): Tiny airsac found in the mammalian the heart or blood vessels. lungs at the end of the air passages (bronchioles) that make Caudate nucleus: A nucleus located within the basal ganglia of up most of the lung tissue and which are the site of the oxygen the of many animal species. The caudate, originally and carbon dioxide exchange in the lungs; a lung thought to primarily be involved with control of voluntary contains about 150 million alveoli. movement, is now known to be an important part of the Anterior: Towards the front (e.g., the anterior region of the brain’s learning and memory system. brain is located toward the front of the head). CD4+ T­cell: A type of lymphocyte; the main target in the body Antibody: A protein produced by the body’s immune system for infection by HIV. to recognize and fight infectious organisms and other foreign CD8 cell: Also called a cytotoxic T­lymphocyte (CTL), killer substances that enter the body. Each antibody is specific to a T­cell, or suppressor T­cell. A type of white blood cell that particular piece of an infectious organism or other foreign is able to identify and kill cells infected with bacteria, substance. Antibodies develop after the first exposure to a viruses, or other foreign invaders. substance. Cell­mediated immunity: Immune protection provided by the Antigen: Any substance considered foreign to the body that direct action of immune cells. With this type of immune can stimulate the body to produce antibodies against it. protection, the response to infectious micro­organisms is Antiretroviral: A drug that interferes with the ability of a retro­ performed by specific cells—such as CD8 cells, macrophages, virus, such as HIV, to make more copies of itself. and other white blood cells—rather than by antibodies. The Antiretroviral therapy (ART): Medications for the treatment main role of cell­mediated immunity is to fight viral infections. of infection by retroviruses and primarily is used to treat HIV. Centrum semiovale: The found beneath the Apoptosis: Cell death in which the affected cell participates by cerebral cortex. activating a cascade of biochemical reactions that lead to Cerebellar: Pertaining to the , a region of the brain death; also known as programmed cell death or cell suicide. that controls sensory perception and motor functions. Asthma: Chronic inflammation of the lungs and airways Cholesterol: A waxy steroid metabolite found in cell membranes (bronchi and bronchioles), leading to a reversible narrowing and transported in the blood of all animals; high levels of of the airways and breathing difficulties. cholesterol in the blood may contribute to heart disease. Atrial fibrillation: A type of abnormal heart rhythm (i.e., Chronic obstructive pulmonary disease (COPD): Term arrhythmia) that involves the upper chambers (i.e., atria) of referring to chronic bronchitis and emphysema, two conditions the heart; characterized by quivering rather than coordinated in which the airways become narrowed, resulting in chronic contraction of the muscles of the atria. breathing difficulties; in contrast to asthma, the narrowing : The long, thin fiber protruding from a nerve cell that of the airways is only poorly reversible and typically becomes carries integrated nerve signals in the form of electrical signals progressively worse. to other nerve cells. Confidence interval (CI): Statistical measure of the reliability B­lymphocyte: Also known as a B­cell. Infection­fighting of an estimate; the range of values that is likely to include white blood cell that develops in the bone marrow and the actual value of the variable being estimated.

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Glossary

Congestive heart failure: Inability of the heart to supply sufficient ized by confusion, altered level of consciousness and coma blood flow to meet the body’s need, resulting in shortness of (i.e., ). breath, fluid accumulation in the blood vessels and tissues, Genu: The anterior end of the . or coughing; can be caused by myocardial infarction. Gray matter: A generic term for a collection of neuronal cell Coronary heart disease: Failure of the blood vessels of the bodies in the . heart muscle to supply adequate blood and nutrients to the heart muscle and surrounding tissues. Hazard ratio: The effect of an explanatory variable on the hazard or risk of an event occurring; it can be considered an estimate Corpus callosum: The largest connective pathway in the of the relative risk. . It is made of nerve fibers that connect the left

and right sides (hemispheres) of the brain. Highly active anti­retroviral therapy (HAART): Treatment approach for HIV­1 infection that involves the combination Cortex: The outer layer of the largest part of the brain (i.e., of several active drugs (antiretroviral drugs); involves a relatively ) that plays a key role in memory, attention, per­ complex and strict treatment regimen and potentially severe ceptual awareness, thought, language, and consciousness. side effects, which may limit patient compliance with the Cumulative: The combined effect when two or more agents treatment. act together, can be additive or synergistic. Humoral immunity: Term used to describe the body’s antibody­ Cytokines: A family of molecules, produced primarily by cells based immune response, as opposed to its cell­based immune of the immune system, that regulate cellular interactions response (cell­mediated immunity). Immune cells called B­ and other functions. Many cytokines play important roles cells produce antibodies against foreign invaders. in initiating and regulating inflammation. Hypertension: Elevated blood pressure. Cytotoxic T­lymphocyte: Also known as killer T­cell, or suppres­ Inferior: Located below (i.e., toward the feet of) another structure. sor T­cell. A type of white blood cell that is able to identify Innate immune response: Initial immediate immune response and kill cells infected with bacteria, viruses, or other foreign that is not specific to a certain foreign molecule or . invaders. pathogen Insulin resistance: Condition in which normal amounts of Diffusion tensor imaging (DTI): A type of magnetic resonance insulin are inadequate to produce a normal insulin response imaging (MRI) that allows measurement of the restricted from fat, muscle, and liver cells. movement of water molecules in tissues, enabling researchers to analyze the structural integrity particularly of white matter Kaposi’s sarcoma: A tumor caused by a human herpesvirus tracts. that manifests as dark blotches or lesions on the skin as well as in the mouth, gastrointestinal tract, and respiratory tract; Dyslipidemia: Any abnormality in the amount of lipids (e.g., considered a defining illness in AIDS patients. cholesterol or fat) in the blood. Lactic acidosis: A condition characterized by the accumulation Edema: Abnormal accumulation of fluid in a tissue or in one of lactic acid in bodily tissues. or more body cavities. Limbic system: A group of brain structures that together control Electron transport chain: The electron transport system (also such functions as emotion, behavior, and long­term memory. known as respiratory chain) located in the mitochondria, in which electrons released by NADH are passed on to a series Lipoatrophy: The localized loss of fat tissue; typically occurs as of other molecules in successive reactions that provide the result of certain injections or as an adverse reaction to enough energy to drive the synthesis of ATP molecules. certain antiretroviral drugs. Emphysema: Chronic lung disorder characterized by loss of Lipodystrophy: A condition characterized by abnormal or elasticity of the lung tissue. In these patients, the small airways degenerative conditions of the body’s fat tissues. to collapse during forced exhalation. As a result, airflow out Lipoprotein: A compound molecule that contains both a of the lungs is impeded and air becomes trapped in the lungs. protein and a lipid component. Symptoms include shortness of breath on exertion, and an Lymphocyte: A white of type blood cell necessary for the expanded chest. normal immune response; types of lymphocytes include Fibrosis: The formation of scar tissue. T cells, B cells, and natural killer cells.

Forced expiratory volume in 1 second (FEV1): A measure of Macrophage: A type of immune cell that ingests foreign particles lung function; the volume of air that can be exhaled in 1 and microorganisms and synthesizes proteins and other second; to determine the FEV1, the patient is asked to inhale substances important in inflammatory responses, including deeply and then to exhale as hard as he or she can, and the cytokines. volume that is exhaled in the first second is measured. Magnetic resonance imaging (MRI): A noninvasive medical Fulminant hepatic failure: A potentially reversible type of imaging technique used to visualize detailed internal structures; acute liver failure, characterized by rapid progression from allows for differentiation of different soft tissues of the body. early symptoms (e.g., jaundice) to advanced stages character­ MRI uses no radiation but powerful magnetic fields and

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radio frequency fields that act on the nuclei of hydrogen Organelle: A specialized subunit in the cell with a specific atoms in the water molecules found in the body. function (e.g., mitochondria are organelles). Metabolite: Intermediary product generated during the Oxidative stress: An imbalance between oxidants (e.g., reactive metabolism of a particular molecule. oxygen species [ROS]) and antioxidants that can lead to excessive Magnetic resonance spectroscopy (MRS): A noninvasive oxidation and cell damage. imaging technique related to magnetic resonance imaging Pathogen: Any microorganism (e.g., virus, bacterium, or fungus) (MRI) that acts by detecting different chemical nuclei (e.g., that can infect an organism and cause disease in the host. phosphorus, carbon, or sodium) within the body in addition Periventricular: Referring to a region near the fluid­filled cavities to the nuclei of hydrogen atoms. (i.e., ventricles) in the brain. Mallory body: An inclusion (or body) typically found in the Phagocytosis: Process by which certain cells (e.g., macrophages) cytoplasm of liver cells of people suffering from alcoholic engulf a solid particle (e.g., a molecule, bacterium, or virus) liver disease. and destroy it within the cell. Microsomal ethanol–oxidizing system (MEOS): An enzyme Pontocerebellar: Referring to a brain system comprising a system involving cytochrome P450 that breaks down alcohol structure in the brain stem (i.e., the pons) and the cerebellum. and generates toxic products, such as acetaldehyde and reactive The pons relays sensory information between the cerebellum oxygen species (ROS). and the largest portion of the brain (i.e., cerebrum) Mitochondria: Structures within cells that generate most of the Postural instability: Inability to keep the body in a stable or cells’ energy through the production of adenosine triphosphate, balanced position. a molecule that provides the energy needed for many key Posterior: Toward the back (e.g., the posterior region of the metabolic reactions. brain is located toward the back of the head). Mitochondrial DNA: DNA molecules found in the mitochondria Proteasome: Large protein complexes in the cell that serve to (rather than in the cell nucleus) and encoding more than 30 break down and eliminate unneeded or damaged proteins. genes, some of which encode proteins involved in the electron Proteasome inhibitor: Agent that inhibits the normal function­ transport chain. ing of the proteasomes, thereby inducing apoptosis; protea­ Monocyte: Type of mononuclear white blood cell; part of the some inhibitors are used in the treatment of certain cancers. body’s immune system with several roles in the body’s Proton spectrum: The different signals emitted by hydrogen immune response. nuclei (i.e., protons) present in different molecules measured Mononuclear cell: White blood cells with a one­lobed nucleus; during magnetic resonance spectroscopy (MRS). include monocytes and lymphocytes. Pulmonary hypertension: Elevated blood pressure in the blood sheath: A white fatty material composed chiefly of vessels connected to or within the lungs, leading to a tightening alternating layers of lipids and lipoproteins that encloses the (vasoconstriction) of those blood vessels and resulting in such of most nerve fibers. symptoms as shortness of breath, dizziness, and fainting. Myocardial infarction: Heart attack; disruption of the blood Quantitative fiber tracking: Computational technique that

supply to a part of the heart, causing death of heart cells; is a indirectly analyzes the anatomy of white matter fiber systems. It does not actually depict anatomic structures but involves complication of coronary heart disease. a statistical analysis of the white matter integrity as determined N­acetyl aspartate (NAA): The second most common compound by diffusion tensor imaging (DTI).

found in the brain that has several important functions in Reactive oxygen species (ROS): Highly reactive oxygen– maintaining normal brain functioning; produces the strongest containing free radicals that are generated during oxidative signal in magnetic resonance spectroscopy (MRS) analyses of metabolism. ROS can react with and damage lipids, proteins, the human brain. and DNA in cells, causing oxidative stress. Nucleoside reverse transcriptase inhibitor (NRTI): A class of Reduced glutathione: An antioxidant that can neutralize reactive medications used to treat HIV infection; they act by inhibiting oxygen species (ROS) and other free radicals. the enzyme reverse transcriptase, which is produced by HIV Relative risk: The ratio of the risk that an event (e.g., develop­ and related viruses and is needed by viruses to reproduce. ment of a disease) occurs in people exposed to a given factor Odds ratio: The ratio of the odds of an event occurring in one (e.g., alcohol consumption) and the risk that the event group of people to the odds of it occurring in another group. occurs in people not exposed to the factor. Opportunistic infection: An infection caused by a pathogen Resonance: When certain nuclei (e.g., hydrogen, phosphorus, that normally does not cause disease in people with a or carbon) are placed in a magnetic field and exposed to healthy immune system but can cause infection in people radio­frequency waves during magnetic resonance imaging with a compromised immune system (e.g., after HIV­1 (MRI) or magnetic resonance spectroscopy (MRS), they absorb infection or organ transplant) energy from waves with a certain frequency and radiate back

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Glossary

this energy with a different frequency; this is called the reso­ with reward, but also aversive, novel, unexpected, or particularly nance frequency. intense stimuli with high salience; includes several nuclei, Seroconversion: The process by which a newly infected person including the caudate nucleus. develops antibodies to HIV. These antibodies then are Subcortical: Located beneath the outer layer (i.e., cortex) of the detectable by an HIV test. Seroconversion may occur anywhere largest portion of the brain (i.e., the cerebrum). from days to weeks or months following HIV infection. Synergistic: The effect when two or more agents act together Septic shock: Shock resulting from infection and sepsis; can to achieve a result that neither of the agents could have cause multiple organ failure and death; occurs most com­ achieved by itself. monly in people with a compromised immune system. Tissue atrophy: Partial or complete wasting away of a tissue; Sepsis: A serious medical condition characterized by inflammatory can result from a variety of causes genetic events, poor nour­ reactions throughout the body resulting from the presence ishment, poor circulation, lack of use of the tissue). of an infection; can lead to septic shock, multiple organ failure, Triglyceride: The chemical form in which most fat molecules and death. exists in food as well as in the body; consist of glycerol and Shock: A serious, life­threatening medical emergency during three fatty acids. which insufficient blood flow to the tissues results in lack of Tumor necrosis factor (TNF­α): A type of cytokine that oxygen and nutrient supply; can be caused by various factors, promotes inflammatory responses, stimulates neutrophils such as trauma or an infection. and macrophages, induces fever, and induces macrophages Splenium: The thickened posterior border of the corpus callosum. to produce cytokines.

Steatohepatitis: A type of liver disease characterized by inflam­ Viral load: Amount of virus in a given volume of fluid (e.g.,

mation of and fat accumulation in the liver. blood); is a measure of the severity of infection. Viremia: Presence of viruses in the blood. Steatosis: The abnormal retention of lipids in the cells, indicating an impairment of normal triglyceride metabolism. Virion: A mature virus particle that exists freely outside a host cell. Striatum: A part of the brain that is involved in the planning of Wasting: Unintentional substantial weight loss movement pathways as well as in other cognitive processes; White matter: A generic term for a collection of nerve cell in the striatum is activated by stimuli associated fibers (i.e., axons) in the central nervous system.

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