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.

 

 

I
  • I5-lipoxygenase - An enzyme that leads to the production of leukotrienes, which are chemicals that contribute significantly to inflammation.
  • ibuprofen - A compound that is effective for relief of pain, fever and inflammation. Ibuprofen inhibits prostaglandin synthesis and acts as a PPAR-gamma activator. Common brand names include Motrin® and Advil®.
  • IL-1 - Abbreviation for interleukin-1.
  • IL-1 beta - A cytokine that is overexpressed in various inflammatory diseases. IL-1 beta activates glial cells and is responsible for other activities involved in the inflammatory response.
  • immune system - The cells and tissues involved in recognizing and attacking foreign substances in the body.
  • immunocytochemistry (IC) - A method of staining cells with antibodies to pinpoint the location of the huntingtin protein under a microscope.
  • immunohistochemistry (IH) - A method of staining tissue slices with antibodies to pinpoint the location of the huntingtin protein under a microscope.
  • immunosuppressant - A drug that suppresses the action of the immune system and is often used after organ transplant surgery to prevent the body from rejecting the organ.
  • immunostaining - Any use of an antibody and some coloring agent to detect a specific protein in a cell or tissue sample.
  • implant - See implantation.
  • implantation - The process by which an embryo attaches to the wall of the uterus.
  • implicit memory - Motor memories or memories that deal with procedures (i.e. riding a bicycle). Often considered "unconscious" memories.
  • impulse (nerve impulse) - The signal that travels along the length of a nerve fiber and ends in the release of neurotransmitters. Nerve impulses are the means by which information is transmitted along the neuron and throughout the nervous system.
  • in vitro - Latin phrase for "in glass"; in a test tube or other artificial environment, as opposed to inside a living organism.
  • in vivo - Latin phrase for "in the living"; in the living body of a plant or animal.
  • inclusion bodies - Another term for neuronal inclusions.
  • independent assortment - Process by which each chromosome is shuffled into a daughter cell during meiosis. Chromosomes do not remain associated with their homologues.
  • inducible nitric oxide synthetase (iNOS) - An enzyme responsible for the production of the free radical nitric oxide.
  • inferior olive - Part of the brain that sends sensory information to the cerebellum.
  • inflammation - The reaction that occurs in the affected cells and adjacent tissues in response to an injury or abnormal stimulation caused by a physical, chemical, or biological substance.
  • inflammatory bowel disease - A chronic inflammatory disease that can affect any part of the gastrointestinal tract but most commonly affects a part of the small intestine.
  • inflammatory mediators - Molecules that are released by immune cells when harmful agents invade the body.
  • inflammatory response - See inflammation.
  • incidence - The number of new events (such as being born with HD) in a population during a specified period.
  • inhibition - One of the responses caused by specific neurotransmitters binding to receptors on a neuron. Inhibition decreases the probability that neurotransmitters will be released by the neuron.
  • inner cell mass - A group of cells found in the blastocyst that give rise to all the tissues of the embryo.
  • iNOS - Abbreviation for inducible nitric oxide synthetase.
  • inosital hexaniacinate - A variation of niacin. Inosital hexaniacinate is recommended by some doctors for individuals who need large amounts of niacin because it has not been linked with any of the usual niacin toxicity found by some studies.
  • Institutional Review Board (IRB) - An IRB is an independent ethics committee for an institution that serves to approve, monitor, and review biomedical and behavioral research involving humans with the aim to protect the rights and welfare of the subjects.
  • insulin - A hormone involved in the storage of glucose (sugar) in tissues. Insulin helps regulate glucose concentration in the blood.
  • interleukin-1 (IL-1) - A cytokine that mediates various inflammatory activities. Production of mature IL-1 requires caspase activity.
  • interleukin-beta - A cytokine that mediates various activities of the inflammatory response.
  • interphase - Stage of the cell cycle that occurs between divisions. DNA is replicated during this phase.
  • intestines - The part of the gastrointestinal tract through which food passes after passing through the stomach. The intestines finish the process of digestion and carry out nutrient absorption.
  • intracellular - Inside a cell.
  • intracellular receptor - Receptor located inside of a cell.
  • in-vitro fertilization (IVF) - The process by which eggs and sperm are combined in a laboratory setting outside of the body.
  • ion - An atom or group of atoms that carries a positive or negative electric charge as a result of having lost or gained one or more electrons (negatively-charged particles). An example of an ion is Na+ (a sodium atom that has become positively charged by losing an electron).
  • ion channels - Passageways in the cell membrane through which charged molecules can pass.
  • iron - An element that plays a role in the transport of oxygen by the blood.
  • isocortex - Another term for neocortex.