0.5 Glossary  (Page 9/18)

I

• iatrogenic disease disease caused by or acquired during a medical procedure
• icosahedral three-dimensional, 20-sided structure with 12 vertices
• IgA antibody dimer primarily found in breast milk, mucus, saliva, and tears
• IgD membrane-body antibody monomer functioning as receptor on the surface of B cells
• IgE antibody monomer involved in defense against parasites and allergic reactions
• IgG antibody monomer most abundant in serum; able to cross placenta; most versatile class of antibody in terms of function
• IgM antibody that is a monomer when functioning as a receptor on surface of B cells but a pentamer when secreted in response to specific pathogens; first antibody to respond during primary and secondary responses
• illuminator the light source on a microscope
• image point (focus) a property of the lens and the distance of the object to the lens; the point at which an image is in focus (the image point is often called the focus)
• imidazoles class of antifungal drugs that inhibit ergosterol biosynthesis
• immune complex large group of antigens bound by antibodies; large enough to settle out of fluid suspension
• immunochromatographic assay assay in which fluids are pulled through test strips by capillary action and antigen captured by mobile antibody-colored bead conjugates; a second, fixed antibody localizes the colored bead, allowing visualization
• immunocytochemistry (ICC) staining technique in which cells are fixed and holes dissolved in the membrane to allow passage of labeled antibodies to bind specific intracellular targets
• immunoelectrophoresis (IEP) assay following protein electrophoresis (PAGE) of serum, in which antisera against specific serum proteins are added to troughs cut parallel to the electrophoresis track, causing the formation of precipitin arcs
• immunofiltration technique in which antibody or antigen can be concentrated by passing fluids through porous membranes, and target molecules are captured as they pass
• immunofluorescence a technique that uses a fluorescence microscope and antibody-specific fluorochromes to determine the presence of specific pathogens in a specimen
• immunoglobulin antibody
• immunohistochemistry (IHC) staining technique in which labeled antibodies are bound to specific cells in a tissue section
• immunology the study of the immune system
• immunostain use of EIA technology to deliver stain to particular cells in a tissue (immunohistochemistry) or specific targets within a cell (immunocytochemistry)
• impetigo a skin infection that may result in vesicles, blisters, or bullae especially around the mouth, commonly caused by Staphylococcus aureus , S. pyogenes, or a combination of both S. aureus and S. pyogenes
• in vitro outside the organism in a test tube or artificial environment
• in vivo inside the organism
• inactivated vaccine vaccine composed of whole pathogen cells or viruses that have been killed or inactivated through treatment with heat, radiation, or chemicals
• incidence the number of individuals with new infections of a particular disease in a given period of time
• inclusion conjunctivitis inflammation of the conjunctiva in newborns caused by Chlamydia trachomatis transmitted during childbirth
• inclusions prokaryotic cell cytoplasmic structures for storing specific nutrients and other resources needed by cells
• incubation period the first stage of acute disease, during which the pathogen begins multiplying in the host and signs and symptoms are not observable
• indirect agglutination assay assay that can be used to detect the agglutination of small latex beads; beads may be coated with antigen when looking for the presence of specific antibodies, or with antibody when looking for the presence of antigen
• indirect antiglobulin test (IAT) see indirect Coombs’ test
• indirect contact transmission transfer of an infectious agent between hosts through contact with a fomite
• indirect Coombs’ test assay, performed in vitro prior to blood transfusions, that looks for antibodies against red blood cell antigens (other than the A and B antigens) that are unbound in a patient’s serum
• indirect ELISA EIA in which an antigen from a pathogen is first attached to the wells of a microtiter plate; the antigen then captures antibodies from patient serum to determine whether the patient currently has or previosly had the disease
• indirect fluorescent antibody test assay for antigen-specific antibodies wherein the antigen captures the antibody, which is subsequently detected using a labeled anti-immunoglobulin mAb
• induced mutation mutation caused by a mutagen
• inducer small molecule that either activates or represses transcription
• inducible operon bacterial operon, typically containing genes encoding enzymes in a degradative pathway, whose expression is induced by the substrate to be degraded when the substrate is available for the cell to use, but that is otherwise repressed in the absence of the substrate
• induction prophage DNA is excised from the bacterial genome
• infection the successful colonization of a microorganism within a host
• infectious arthritis (septic arthritis) inflammation of joint tissues in response to a microbial infection
• infectious disease disease caused by a pathogen
• infectious mononucleosis common and mild infection caused by Epstein-Barr virus (HHV-4) or cytomegalovirus (HHV-5); transmitted by direct contact with body fluids such as saliva
• inflammation innate nonspecific immune response characterized by erythema, edema, heat, pain, and altered function, typically at the site of injury or infection but sometimes becoming systemic.
• influenza highly contagious and acute viral disease of the respiratory tract caused by the influenza virus
• initiation factors proteins that participate in ribosome assembly during initiation
• initiation of DNA replication stage of replication during which various proteins bind to the origin of replication to begin the replication process
• initiation of transcription stage of transcription during which RNA polymerase binds to a promoter and transcription begins
• initiation of translation stage of translation during which an initiation complex composed of the small ribosomal subunit, the mRNA template, initiation factors, GTP, and a special initiator tRNA forms, and the large ribosomal subunit then binds to the initiation complex
• inoculum small number of cells added to medium to start a culture
• inorganic phosphate (P _i ) single phosphate group in solution
• insertion type of mutation involving the addition of one or more bases into a DNA sequence
• integrase inhibitors antiviral drugs that block the activity of the HIV integrase responsible for recombination of a DNA copy of the viral genome into the host cell chromosome
• intercalating agent molecule that slides between the stacked nitrogenous bases of the DNA double helix, potentially resulting in a frameshift mutation
• interference distortion of a light wave due to interaction with another wave
• interferons cytokines released by cells that have been infected with a virus; stimulate antiviral responses in nearby cells as well as the cells secreting the interferons
• interleukins cytokines largely produced by immune system cells that help coordinate efforts against invading pathogens
• intermediate filament one of a diverse group of cytoskeletal fibers that act as cables within the cell and anchor the nucleus, comprise the nuclear lamina, or contribute to the formation of desmosomes
• intermediate host a host in which a parasite goes through some stages of its life cycle before migrating to the definitive host
• intermittent common source spread a mode of disease transmission in which every infection originates from the same source and that source produces infections for a period before stopping and then starting again
• intertrigo a rash that occurs in a skin fold
• intestinal fluke a trematode worm that infects the intestine, often caused by Fasciolopsis buski
• intracellular targeting toxin see A-B exotoxin
• intrinsic growth rate genetically determined generation time under specific conditions for a bacterial strain
• intron intervening sequence of a eukaryotic gene that does not code for protein and whose corresponding RNA sequences are removed from the primary transcript during splicing
• intubation placement of a tube into the trachea, generally to open the airway or to administer drugs or oxygen
• in-use test a technique for monitoring the correct use of disinfectants in a clinical setting; involves placing used, diluted disinfectant onto an agar plate to see if microbial colonies will grow
• invasion dissemination of a pathogen through local tissues or throughout the body
• iodophor compound in which iodine is complexed to an organic molecule, increasing the stability and efficacy of iodine as a disinfectant
• ionizing radiation high-energy form of radiation that is able to penetrate surfaces and sterilize materials by damaging microbial cell components and DNA
• ischemia condition marked by the inadequate flow of blood to the tissues
• isograft tissue grafted from one monozygotic twin to another
• isohemagglutinins IgM class antibodies produced against A or B red blood cell antigens
• isomers molecules that have the same atomic makeup but differ in the structural arrangement of the atoms
• isoniazid antimetabolite that inhibits biosynthesis of mycolic acid; used for the treatment of mycobacterial infections
• isoprenoid branched lipid derived from five-carbon isoprene molecules
• isotonic medium a solution in which the solute concentrations inside and outside the cell are approximately equal, thereby creating no net movement of water molecules across the cell membrane
• ivermectin antihelminthic drug of the avermectin class that binds to invertebrate glutamate-gated chloride channels to block neuronal transmission in helminths