Medical Dictionary

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isocytolysin (i′so-si-tol′i-sin)
A cytolysin that reacts with the cells of certain other animals of the same species, but not with the cells of the individual that formed the i..

isodactylism (i-so-dak′ti-lizm)
Condition in which the fingers or toes are all approximately of equal length. [iso- + G. daktylos, finger]

isodense (i′so-dens)
Denoting a tissue having a radiopacity (radiodensity) similar to that of another or adjacent tissue.

isodesmosine (i-so-des′mo-sen)
A cross-linking amino acid formed from lysyl residues; found in elastin.

isodose
Area of equivalent radiation dose. [iso- + dose]

isodulcit (i-so-dul′sit)
SYN: l-rhamnose.

isodynamic (i′so-di-nam′ik)
1. Of equal force or strength. 2. Relating to foods or other materials that liberate the same amount of energy on combustion. [iso- + G. dynamis, force]

isodynamogenic (i′so-di-na-mo-jen′ik, -di-nam′o-)
1. SYN: isoenergetic. 2. Producing equal nerve force. [iso- + G. dynamis, force, + -gen, producing]

isoelectric (i′so-e-lek′trik)
Of equal electrical potential. Cf.:i. point. SYN: isopotential. i. focusing electrophoresis of small molecules or macromolecules in a pH gradient.

isoenergetic (i′so-en-er-jet′ik)
Exerting equal force; equally active. SYN: isodynamogenic (1) .

isoenzyme (i-so-en′zim)
One of a group of enzymes that catalyze the same reaction but may be differentiated by variations in physical properties, such as isoelectric point, electrophoretic mobility, kinetic parameters, or modes of regulation; e.g., lactate dehydrogenase, a tetramer composed of varying amounts of α and β subunits ( i.e., 4α, 3α + 1β, 2α + 2β, 1α + 3β, and 4β). SYN: isozyme. creatine kinase isoenzymes the isoenzymes of creatine kinase. Creatine kinase is a dimer with M (muscle) and/or B (brain) subunits; it exists in three i. forms: CK-MM, the predominant form, found primarily in skeletal muscle; CK-MB, found in cardiac muscle, tongue, diaphragm, and in small amounts in skeletal muscle; and CK-BB found in the brain, smooth muscle, thyroid, lungs, and prostate. Elevations detected by electrophoresis or other methodologies can be used to help in the differential diagnosis of a variety of disease states, with CK-MB elevations as an important marker following myocardial infarctions, elevations in CK-MM an indicator of muscle disease, and increases in CK-BB an occasional finding following brain infarcts, bowel infarcts, or in the presence of certain malignancies.

isoerythrolysis (i′so-e-rith-rol′i-sis)
Destruction of erythrocytes by isoantibodies. [iso- + erythrocyte = G. lysis, dissolution] neonatal i. 1. i. in the newborn animal; 2. hemolytic icterus of the newborn.

isofluorphate (i-so-flor′fat)
A toxic cholinergic agent that acts by irreversible inhibition of cholinesterase; an ophthalmic cholinergic agent used in the treatment of glaucoma; also used in biochemical research as an enzyme inhibitor. SYN: diisopropyl fluorophosphate.

isoflurane (i-so-floor′an)
A nonflammable, nonexplosive, halogenated ether with potent anesthetic action; an isomer of enflurane.

isogamete (i-so-gam′et)
1. One of two or more similar cells that conjugate or fuse and subsequently divide, resulting in reproduction. 2. A gamete of the same size as the gamete with which it unites. [iso- + G. gametes or gamete, husband or wife]

isogamy (i-sog′a-me)
Conjugation between two equal gametes or two individual cells alike in all respects. [iso- + G. gamos, marriage]

isogeneic, isogenic (i′so-je-ne′ik, -jen′ik)
SYN: syngeneic.

isogenous (i-soj′e-nus)
Of the same origin, as in development from the same tissue or cell. [iso- + G. genos, family, kind]

isogentiobiose (i′so-jen-shi-o-bi′os)
SYN: isomaltose.

isoglutamine (i-so-gloo′ta-men)
A glutamic amide.

isognathous (i-sog′na-thus)
Having jaws of approximately the same width. [iso- + G. gnathos, jaw]

isograft (i′so-graft)
SYN: syngraft.

isohemagglutination (i′so-he′ma-gloo′ti-na′shun)
SYN: isoagglutination. [iso- + G. haima, blood, + L. ad, to, + gluten, glue]

isohemagglutinin (i′so-he′ma-gloo′ti-nin)
SYN: isoagglutinin.

isohemolysin (i′so-he-mol′i-sin)
An isolysin that reacts with red blood cells.

isohemolysis (i′so-he-mol′i-sis)
A form of isolysis in which there is dissolution of red blood cells as a result of the reaction between an isolysin (isohemolysin) and specific antigen in or on the cells. [iso- + G. haima, blood, + lysis, dissolution]

isohydric (i-so-hi′drik)
Denoting two substances possessing the same pH.

isohydruria (i′so-hi-droo′re-a)
Fixation of the pH of the urine without the usual variation. [iso- + G. hydor, water, + ouron, urine, + -ia]

isoimmunization (i′so-im′u-ni-za′shun)
Development of a significant titer of specific antibody as a result of antigenic stimulation with material contained on or in the red blood cells of another individual of the same species; e.g., i. is likely to occur when an Rh-negative person is treated with a transfusion of Rh-positive blood from another human being, or an Rh-negative woman has a pregnancy in which the fetus inherits Rh-positive red blood cells.

isolate (i′so-lat)
1. To separate, to set apart from others; that which is so treated. 2. To free of chemical contaminants. 3. In psychoanalysis, to separate ideas, experiences, or memories from the affects pertaining to them. 4. In group psychotherapy, an individual who is not responded to by others in the group. 5. Viable organisms separated on a single occasion from a sample taken from a host or culture system. 6. A population that for geographic, linguistic, cultural, social, religious, or other reasons is subject to little or no gene flow. SYN: genetic i.. [It. isolare; Mediev. L. insulo, pp. -atus, to insulate, fr. L. insula, island] genetic i. SYN: i. (6) . mating i. a population separated from its neighbors by any means so that all or most matings occur within the population group.

isolation
1. In microbiology, separation of an organism from others, usually by making serial cultures. 2. Separation for the period of communicability of infected persons or animals from others, so as to prevent or limit the direct or indirect transmission of the infectious agent from those who are infected to those who are susceptible.

isolecithal (i-so-les′i-thal)
Denoting an ovum in which there is a moderate amount of uniformly distributed yolk.

isoleucine (I) (i-so-loo′sen)
2-Amino-3-methylvaleric acid;the l-amino acid found in almost all proteins; an isomer of leucine and, like it, a dietary essential amino acid.

isoleucyl (i-so-loo′sil)
The acyl radical of isoleucine.

isoleukoagglutinin (i′so-loo′ko-a-gloo′ti-nin)
Abnormal antibody in the blood of some persons, capable of agglutinating human leukocytes.

isologous (li-sol′o-gus)
SYN: syngeneic. [iso- + G. logos, ratio]

isolysin (i-sol′i-sin)
An antibody that combines with, sensitizes, and results in complement-fixation and dissolution of cells that contain the specific isoantigen; isolysins occur in the blood of some members of a species and they react with the cells of that species, but not with the cells of the individual (or the same type) in which the isolysins are naturally formed.

isolysis (i-sol′i-sis)
Lysis or dissolution of cells as a result of the reaction between an isolysin and specific antigen in or on the cells. SEE ALSO: isohemolysis. [iso- + G. lysis, dissolution]

isolytic (i-so-lit′ik)
Pertaining to, characterized by, or causing isolysis.

isomaltase (i-so-mal′tas)
SYN: oligo-α-1,6-glucosidase. SEE ALSO: sucrose α-d-glucohydrolase.

isomaltose (i-so-mal′tos)
A disaccharide in which two glucose molecules are attached by an α-1,6 link, rather than an α-1,4 link as in maltose. SYN: isogentiobiose.

isomastigote (i-so-mas′ti-got)
Denoting a protozoan having two or four flagella of equal length at one extremity. [iso- + G. mastix, whip]

isomer (i′so-mer)
1. One of two or more substances displaying isomerism (q.v.); e.g., l-glucose and d-glucose or citrate and isocitrate. Cf.:stereoisomer. 2. One of two or more nuclides having the same atomic and mass numbers but differing in energy states for a finite period of time; e.g., 99mTc and 99Tc. [iso- + G. meros, part] geometric i. geometric isomerism.

isomerase (i-som′er-as)
A class of enzymes (EC class 5) catalyzing the conversion of a substance to an isomeric form; e.g., glucosephosphate i..

isomeric (i-so-mar′ik)
Relating to or characterized by isomerism. SYN: isomerous.

isomerism (i-som′er-izm)
The existence of a chemical compound in two or more forms that are identical with respect to percentage composition but differ as to the positions of one or more atoms within the molecules, as well as in physical and chemical properties. geometric i. a form of i. displayed by unsaturated or ring compounds where free rotation about a bond (usually a carbon-carbon bond) is restricted; e.g., the i. of a cis- or trans- compound as in oleic acid and elaidic acid. Cf.:cis-, entgegen, trans-, zusammen. optic i. stereoisomerism involving the arrangement of substituents about an asymmetric atom or atoms (usually carbon) so that there is a difference in the behavior of the various isomers with regard to the extent of their rotation of the plane of polarized light. Cf.:stereoisomerism. stereochemical i. SYN: stereoisomerism. structural i. i. involving the same atoms in different arrangements; e.g., the butyric acids, leucine and isoleucine, glucose and fructose.

isomerization (i-som′er-i-za′shun)
A process in which one isomer is formed from another, as in the action of isomerases. enzyme i. reversible changes in enzyme conformation.

isomerous (i-som′er-us)
SYN: isomeric.

isomethadone (i-so-meth′a-don)
A narcotic analgesic.

isometheptene (i′so-meth-ep′ten)
An unsaturated aliphatic sympathomimetic amine with antispasmodic and vasoconstrictor actions.

isometric (i-so-met′rik)
1. Of equal dimensions. 2. In physiology, denoting the condition when the ends of a contracting muscle are held fixed so that contraction produces increased tension at a constant overall length. Cf.:auxotonic, isotonic (3) , isovolumic. [iso- + G. metron, measure]

isometropia (i′so-me-tro′pe-a)
Equality in refraction in the two eyes. [iso- + G. metron, measure, + ops (op-), eye]

isomorphic (i-so-mor′fik)
SYN: isomorphous.

isomorphism (i-so-mor′fizm)
Similarity of form between two or more organisms or between parts of the body. [iso- + G. morphe, shape]

isomorphous (i-so-mor′fus)
Having the same form or shape, or being morphologically equal. SYN: isomorphic.

isonaphthol (i-so-naf′thol)
See naphthol.

isoncotic (i-son-kot′ik)
Of equal oncotic pressure.

isoniazid (i-so-ni′a-zid)
Isonicotinic acid hydrazide;first-line and probably most commonly used antituberculosis drug. Organisms rapidly develop resistance against this drug if it is used alone in the treatment of active disease. Hepatic toxicity is the major side effect.

isonicotinic acid (i-so-nik-o-tin′ik)
The substance of which the hydrazide is isoniazid.

isonitrile (i-so-ni′tril)
An organic isocyanide.

isonitrosoacetone (i′so-ni-tro-so-as′e-ton)
A cholinesterase reactivator that can penetrate the blood-brain barrier readily and cause significant reactivation of phosphorylated acetylcholinesterase in the central nervous system; used to protect human beings and animals against otherwise lethal poisoning with organophosphorous anticholinesterase agents. SYN: monoisonitrosoacetone, pyruvaldoxine.

iso-osmotic (i′so-os-mot′ik)
SYN: isosmotic.

isopathy (i-sop′a-the)
Treatment of disease by means of the causal agent or a product of the same disease; or treatment of a diseased organ by an extract of a similar organ from a healthy animal. SEE ALSO: homeopathy. [iso- + G. pathos, suffering]

isopentenylpyrophosphate (i-so-pen-ten-il′pi-ro-fos′fat)
An intermediate in the biosynthesis of steroids, terpenes, dolichol, and prenylated proteins.

isopentyl (i-so-pen′til)
See amyl.

isopeptide (i-so-pep′tid)
See i. bond.

isophagy (i-sof′a-je)
SYN: autolysis. [iso- + G. phago, to eat]

isoplassonts (i-so-plas′onts)
Like-formed entities having certain features in common. [iso- + G. plasso, to form]

isoplastic (i-so-plas′tik)
SYN: syngeneic. [iso- + G. plasso, to form]

isopleth (i′so-pleth)
A line on a Cartesian nomogram consisting of all points that represent a particular value of a variable; e.g., an isobar is an i. for a particular pressure.

isopotential (i′so-po-ten′chul)
SYN: isoelectric.

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