HD Glossary

Note: Some words can have differing definitions depending on the context in which they are used. The definitions presented here are the ones that best apply to the words as they are used. HDSA is grateful to the Stanford Hopes website for their contribution and maintenance of this glossary.

 

 

B
  • backup - The optimized drug that is selected as the next most likely to be successfully developed as a therapy in further experiments and trials, and will be used if the lead compound is not successful.
  • bacteria - A small, single-celled living organism that has DNA and can replicate its own DNA without the help of a host cell. Some bacteria are helpful to humans, such as those that live in our stomach and help with digestion, while some are harmful, releasing toxins or poisonous waste products.
  • ballismus - uncontrolled, violent movements
  • basal ganglia - A group of nerve cells located at the base of the brain. It is composed of the putamen, caudate, globus pallidus, and substantia nigra. (The putamen and caudate together make up the striatum.) The basal ganglia participate in the regulation of motor performance, among other things. (Singular form: basal ganglion.)
  • basal ganglion - Singular form of basal ganglia.
  • base - A general term referring to the subunits of DNA or RNA. The four DNA bases are A, C, G, and T.
  • baseline firing rate - cells release neurotransmitters at a constant rate under normal conditions
  • basic - Adjective used to describe a substance or solution that contains a relatively low amount of positive hydrogen ions.
  • Batten disease - A fatal, inherited disorder of the nervous system that begins in childhood; the most common form of a group of disorders called neuronal ceroid lipofuscinoses (NCLs). Early symptoms usually appear between the ages of 5 and 10 in the form of vision problems, seizures, personality and behavior changes, slow learning, clumsiness, or stumbling. Eventually, affected children suffer mental impairment, worsening seizures, and progressive loss of sight and motor skills. Batten disease is often fatal by the late teens or twenties.
  • battenin - The key protein involved in Batten disease.
  • Bax - A molecule that usually exists in a cell's cytosol. It plays a role in initiating the apoptosis pathway by aggravating the mitochondria's membrane.
  • benign tumor - An abnormal mass of tissue that replicates uncontrollably, but will not spread to other tissues.
  • basic research - Research driven by scientists’ interest in questions pertaining to the biology behind a process or disease.
  • beta-amyloid - A compound that tends to accumulate in the brains of people with Alzheimer's disease. It consists primarily of proteins that are in sheet or ribbon-like formations called beta-amyloid fibrils, which are responsible for the beta-amyloid plaques seen in Alzheimer's. Beta-amyloid is also known as simply amyloid.
  • beta-amyloid fibrils - A group primarily composed of proteins that lay flatly upon one another like sheets of paper. These are responsible for the amyloid plaques seen in Alzheimer's disease. Also known as simply amyloid fibrils.
  • beta-amyloid plaques - Thick deposits of proteins in the brain that are believed to play a role in nerve cell degeneration in Alzheimer's disease. Also known as simply amyloid plaques.
  • beta blocker - Drugs that block the action of certain hormones on the heart. Beta blockers reduce the heart rate and the force of muscle contraction, thereby reducing the oxygen demand of heart muscles.
  • beta oxidation - The process by which fats, in the form of Acyl-CoA molecules, are broken down in the mitochondria to generate Acetyl-CoA, the entry molecule for the Krebs Cycle.
  • beta sheet - A three-dimensional structure of a protein that takes on a flat, pleated appearance.
  • beta wave - A type of brain wave; occurs during times of active thinking.
  • bile - A fluid produced by the liver and stored in the gall bladder. It plays an important role in digestion by helping to break down fats and absorb vitamins.
  • bile salts - A product produced in the liver from cholesterol. Bile salts aid in the breakdown of dietary fats.
  • bilobalide - A component of the terpenoids that has been shown to have neuroprotective properties though its role in motor nerve cell regeneration.
  • biological target - An enzyme, receptor or other protein that can be modified by an external stimulus, such as a drug, a hormone, molecule, or another protein.
  • biomarker - A specific biological trait, such as the level of a certain molecule in the body, that can be measured to indicate the progression of a disease or condition.
  • biophysiological - Referring to the internal biological processes that occur in the body.
  • biopsy - a medical test to remove cells or tissue from a body to test them for a disease condition. The tissue can either be looked at under a microscope or analyzed using chemical tests. Biopsies are usually taken when the cause or extent of a disease is uncertain.
  • biosynthesis - The production of chemical compounds by living organisms.
  • bipolar disorder - also known as manic-depression, this disorder is characterized by alternating periods of extreme moods. For example, a period of mania may be characterized by excessive energy, restlessness and/or irritability. This period of mania may be followed by a period of depression characterized by feelings of hopelessness and a lack of energy.
  • biotechnology - Biotechnology is technology based on biology, especially when used in agriculture, food science, research, and medicine. When used in research and medicine, some examples are the designing of organisms to produce antibiotics, and the methods to look at the function of naturally occurring proteins.
  • bivalent - A physical connection between homologous chromosomes that forms during meiosis. Crossing over takes place when the chromosomes are in this orientation.
  • blastocyst - An early stage of embryo development made up of a hollow sphere and an inner cell mass.
  • blood-brain barrier - A group of cells that form a special, impermeable lining in the blood vessels of the brain. The blood-brain barrier is made up of astrocytes and prevents toxic substances in the blood from entering the brain.
  • blood vessels - A tube through which the blood circulates in the body. Blood vessels include a network of arteries, arterioles, capillaries, venules, and veins.
  • bovine spongiform encephalopathy (BSE) - A form of transmissible spongiform encephalopathy (TSE) that affects cattle.
  • bradykinesia - difficulty initiating and continuing movements; literally means slow moving
  • brain stem - The portion of the brain closest to the spinal cord. It consists of the medulla, pons, and midbrain and controls many of the involuntary functions that keep us alive.
  • brain-derived neurotrophic factor (BDNF) - A protein that causes certain types of nerve cells to survive and grow. BDNF is primarily located in the central nervous system, where it acts on cells in the brain and the eye. In the peripheral nervous system, BDNF promotes the growth of sensory and motor neurons.
  • bulbar region - An area of the brain composed of the cerebellum, medulla and pons. (Basically, the bulbar region is made up of the brain stem minus the midbrain and plus the cerebellum). The bulbar region is responsible for many involuntary functions that keep us alive.