Medical Dictionary

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interfascicular (in′ter-fa-sik′u-lar)
Between fasciculi.

interfemoral (in-ter-fem′o-ral)
Between the thighs.

interference (in-ter-fer′ens)
1. The coming together of waves in various media in such a way that the crests of one series correspond to the hollows of the other, the two thus neutralizing each other; or so that the crests of the two series correspond, thus increasing the excursions of the waves. 2. Collision within the myocardium of two waves of excitation at the junction of territories controlled by each, as is seen in AV dissociation. 3. Also, in AV dissociation, the disturbance of the regular rhythm of the ventricles by a conducted impulse from the atria, e.g., by a ventricular capture (i. beat). 4. The condition in which infection of a cell by one virus prevents superinfection by another virus, or in which superinfection prevents effects which would result from infection by either virus alone, even though both viruses persist. [inter- + L. ferio, to strike] bacterial i. the condition in which colonization by one bacterial strain prevents colonization by another strain. cuspal i. SYN: deflective occlusal contact.

interferometer (in′ter-fe-rom′e-ter)
An instrument for measuring minute distances or movements through the interference of light waves thereby produced. [interfere + G. metron, measure] electron i. an i. that employs an electron beam in place of a light beam.

interferometry (in′ter-fe-rom′e-tre)
Measurement of mi-nute distances or movements by interaction of waves of electromagnetic energy. electron i. i. in which a beam of electrons is used instead of a beam of light.

interferon (IFN) (in-ter-fer′on)
A class of small protein and glycoprotein cytokines (15–28 kD) produced by T cells, fibroblasts, and other cells in response to viral infection and other biological and synthetic stimuli. Interferons bind to specific receptors on cell membranes; their effects include inducing enzymes, suppressing cell proliferation, inhibiting viral proliferation, enhancing the phagocytic activity of macrophages, and augmenting the cytotoxic activity of T lymphocytes. Interferons are divided into five major classes (alpha, beta, gamma, tau, and omega) and several subclasses (indicated by Arabic numerals and letters) on the basis of physicochemical properties, cells of origin, mode of induction, and antibody reactions. [interfere + -on] The discovery in 1957 that viral infection of human cells induces the formation of natural antiviral agents raised the hope that these substances might have therapeutic potential. Early studies showed that, unlike antibodies, interferons are active against a broad range of viruses, but progress in applying this knowledge to human medicine was retarded by the difficulty of producing interferons in sufficient quantity. In the 1980s the development of recombinant DNA technology overcame this obstacle, and interferons now play an important role in the treatment not only of viral infections but also of certain malignancies. Commercially available interferons are produced by genetically altered colonies of Escherichia coli or Chinese hamster ovary cells, or are induced by controlled viral infection in pooled human leukocytes. Alpha interferons have found the widest application in medicine. (The spelling alpha is used with respect to naturally occurring interferons; in compliance with international conventions for generic drug names, the spelling alfa appears in names of pharmaceutical formulations.) Alpha interferons are used in the treatment of chronic hepatitis B and hepatitis C, hairy cell leukemia, chronic myelogenous leukemia, AIDS-related Kaposi sarcoma, malignant melanoma, condylomata acuminata and recurrent respiratory papillomatosis due to human papillomavirus, and infantile hemangiomatosis. About 50% of patients treated for chronic hepatitis B with i.-alfa show disappearance of hepatitis Be antigen (HBeAg) and reversion of alanine aminotransferase to normal. The response rate in chronic hepatitis C is lower (15–25%), but better results are achieved by using more aggressive therapy (daily rather than thrice weekly administration) and continuing it longer (a minimum of 12 months). Modified formulations of i.-alfa conjugated with polyethylene glycol (PEG), which have yielded promising results in hepatitis C with once-a-week dosing, are in phase III trials. Beta interferons reduce clinical recurrences and progression of myelin damage in multiple sclerosis. Gamma i. is effective in retarding tissue changes in osteopetrosis and systemic scleroderma and in reducing the frequency and severity of infections in chronic granulomatous disease. Administration of interferons is parenteral (intravenous, intramuscular, subcutaneous, intranasal, intrathecal, or intralesional) and several weeks of treatment may be required before clinical response is noted. More than 50% of patients experience a flulike syndrome of fatigue, myalgia, and arthralgia. Gastrointestinal and CNS side effects are also common, and marrow suppression may occur with prolonged treatment. i. alfa 2b a water-soluble protein (MW 19,271) secreted by cells infected by virus; used to treat hairy cell leukemia, malignant melanoma, condylomata acuminata, AIDS-related Kaposi sarcoma, and chronic hepatitis C. i. alpha (IFN-α) the major i. made by virus-induced leukocytes; a number of different subtypes exist that are elaborated by leukocytes in response to viral infection or to stimulation with double-stranded RNA. There are 14 genes on the short arm of chromosome 9 that code for these substances in humans. IFN-α-2A and -2B are protein products made by recombinant DNA techniques and are used as antineoplastic agents. SYN: leukocyte i.. antigen i. SYN: i. gamma. i. beta (IFN-β) i. elaborated by fibroblasts and microphages in response to the same stimuli as i. alpha; only one gene codes for this i.. SYN: fibroblast i.. i. beta 1b a purified protein containing 165 amino acids (MW approximately 18,500) with antiviral and immunomodulatory effects, used in the treatment of relapsing-remitting multiple sclerosis to reduce the frequency of clinical exacerbations. fibroblast i. SYN: i. beta. i. gamma (IFN-γ) i. elaborated by T lymphocytes in response to either specific antigen or mitogenic stimulation; only one gene codes for γ i.. i. gamma behaves like a biological response modifies and is highly immunoregulatory. SYN: antigen i., immune i.. immune i. SYN: i. gamma. leukocyte i. SYN: i. alpha. i.-omega a form of i. known as i.-alpha-2. i.-tau an i. secreted by bovine concepti, with potent antiretroviral activity; in experimental use. SYN: trophoblast i., trophoblastin. trophoblast i. SYN: i.-tau. type I i. antiviral interferons, including i.-alpha; and i.-beta;. type II i. immune i., i.-gamma;

interferon-β2
SYN: interleukin-6.

interfibrillar, interfibrillary (in′ter-fi′bri-lar, -fi′bri-lar-e; -fi-bril′ar)
Between fibrils.

interfibrous (in-ter-fi′brus)
Between fibers.

interfilamentous (in′ter-fil-a-men′tus)
Between filaments.

interfrontal (in-ter-fron′tal)
Between the unfused halves of the frontal bone; denoting a persistent suture there present. (anomalous)

interganglionic (in′ter-gang′le-on′ik)
Between or among or connecting ganglia.

intergemmal (in′ter-jem′al)
Between any two or more budlike or bulblike bodies such as the taste buds; denoting especially a nerve termination between two end bulbs. [inter- + L. gemma, bud]

intergenal (in-ter-jen′al)
Between different genes.

interglobular (in-ter-glob′u-lar)
Between globules.

intergluteal (in-ter-gloo′te-al)
Between the buttocks. [inter- + G. gloutos, buttock]

intergonial (in-ter-go′ne-al)
Between the two gonia. See gonion. [inter- + G. gonia, angle]

intergyral (in-ter-ji′ral)
Between the gyri or convolutions of the brain.

interhemicerebral (in′ter-hem′e-ser′e-bral)
Between the cerebral hemispheres.

interictal (in-ter-ik′tal)
The period between convulsions. [inter- + L. ictus, stroke]

interior (in-ter′e-or)
Relating to the inside; situated within.

interischiadic (in-ter-is-ke-ad′ik)
Between the two ischia; especially, between the two tuberosities of the ischia. SYN: intersciatic.

interkinesis (in′ter-ki-ne′sis)
Period between the first and second divisions of meiosis; comparable to interphase of mitosis. [inter- + G. kinesis, movement]

interlamellar (in′ter-la-mel′ar, -lam′e-lar)
Between lamellae.

interleukin
The name given to a group of multifunctional cytokines once their amino acid structure is known. They are synthesized by lymphocytes, monocytes, macrophages, and certain other cells. See lymphokine, cytokine. [inter- + leukocyte + -in] recombinant human i. 11 a drug that increases the number of blood platelets; useful in ameliorating severe thrombocytopenia resulting from cancer chemotherapy. SYN: rhIL-11.

interleukin-1 (IL-1) (in-ter-loo′kin)
A cytokine, derived primarily from mononuclear phagocytes, which enhances the proliferation of T helper cells and growth and differentiation of B cells. When secreted in larger quantities it is a mediator of inflammation, entering the bloodstream and causing fever, inducing synthesis of acute phase proteins, and initiating metabolic wasting. There are two distinct forms of IL-1: α and β, both of which perform the same functions, but represent different proteins.

interleukin-2 (IL-2)
A cytokine derived from T helper lymphocytes that causes proliferation of T lymphocytes and activated B lymphocytes.

interleukin-3 (IL-3)
A cytokine derived from activated CD4+ lymphocytes, fibroblasts, and endothelial cells that increases production of monocytes. It acts in hematopoiesis by controlling production and differentiation of granulocytes. SYN: multicolony-stimulating factor.

interleukin-4 (IL-4)
A cytokine derived from T4 lymphocytes that causes differentiation of B lymphocytes. Promotes Ig class switch. It stimulates DNA biosynthesis. SYN: B cell differentiating factor.

interleukin-5 (IL-5)
A cytokine derived from T lymphocytes that causes activation of B lymphocytes and differentiation of eosinophils.

interleukin-6 (IL-6)
A cytokine derived from macrophages and endothelial cells that increases synthesis and secretion of immunoglobulins by B lymphocytes; also induces acute phase proteins. In hepatocytes, it induces acute-phase reactants. SYN: B cell stimulatory factor 2, interferon-β2.

interleukin-7 (IL-7)
A cytokine derived from bone marrow cells that causes proliferation of B and T lymphocytes.

interleukin-8 (IL-8)
A cytokine (chemokine) derived from endothelial cells, fibroblasts, keratinocytes, macrophages, and monocytes which causes chemotaxis of neutrophils and T-cell lymphocytes. SYN: anionic neutrophil-activating peptide, monocyte-derived neutrophil chemotactic factor, neutrophil chemotactant factor, neutrophil-activating factor.

interleukin-9 (IL-9)
A cytokine derived from T cells that causes IL-2/Il-4-independent growth and proliferation of T cells.

interleukin-10 (IL-10)
A cytokine derived from helper T-cell lymphocytes (TH2) that inhibits γ-interferon (IFNγ) and IL-2 secretion by T cell lymphocytes (TH1) and inhibits mononuclear cell inflammation.

interleukin-11 (IL-11)
A cytokine and growth factor derived from bone marrow stromal cells (endothelial cells, macrophages, and preadipocytes) that stimulates increased plasma concentrations of acute phase proteins and is a growth factor with multiple hematopoietic effects.

interleukin-12 (IL-12)
A cytokine derived from B lymphocytes and macrophages that induces γ-interferon (IFNγ) gene expression and IL-2 in T lymphocytes and NK cells and down regulates TH2 cytokines.

interleukin-13 (IL-13)
A cytokine derived from helper T cell lymphocytes that inhibits mononuclear cell inflammation and is considered a modulator or B cell responses.

interleukin-14 (IL-14)
A cytokine derived from T cells that stimulates B cell proliferation and inhibits Ig secretion.

interleukin-15 (IL-15)
A cytokine derived from T cells which stimulates T cell proliferation and NK cell activation.

interleukin-16 (IL-16)
A cytokine made by T cells that is a potent chemotactant for CD4+ T cells.

interleukin-17 (IL-17)
A proinflammatory cytokine made by T cells.

interleukin-18 (IL-18)
A cytokine made by macrophages; a potent inducer of interferon-γ by T cells and NK cells.

interlobar (in-ter-lo′bar)
Between the lobes of an organ or other structure.

interlobitis (in′ter-lo-bi′tis)
Inflammation of the pleura separating two pulmonary lobes.

interlobular (in-ter-lob′u-lar)
Between the lobules of an organ.

intermalleolar (in-ter-mal-e′o-lar)
Between the malleoli.

intermammary (in-ter-mam′a-re)
Between the breasts. [inter- + L. mamma, breast]

intermammillary (in-ter-mam′i-la-re)
Between the breasts; between the nipples; denoting a line drawn between the two nipples. [inter- + L. mammilla, breast, nipple]

intermarriage (in-ter-mar′ij)
1. Marriage of relatives. 2. Marriage of persons of different races or cultures.

intermaxilla (in-ter-maks-il′a)
SYN: incisive bone.

intermaxillary (in-ter-mak′si-la-re)
Between the maxillae, or upper jaw bones.

intermediary (in′ter-me′de-ar-e)
Occurring between. [L. intermedius, lying between, fr. medius, middle]

intermediate (in′ter-me′de-it) [TA]
1. Between two extremes; interposed; intervening. 2. A substance formed in the course of chemical reactions that then proceeds to participate in further reactions; such substances, when appearing in the course of the reactions involved in metabolism, are metabolic intermediates. 3. In dentistry, a cement base. 4. An element or organ between right and left (or lateral and medial) structures. SYN: intermedius [TA] . replicative i. during the copying of the viral RNA of an RNA virus, the opposite sense strand that serves as a template for positive strand production.

intermedin (in-ter-me′din)
SYN: melanotropin.

intermediolateral (in-ter-me′de-o-lat′er-al)
Intermediate, and to one side, not central. Used especially to denote the i. cell column of spinal cord gray mattter, abbreviated IML, the location of all presynaptic sympathetic nerve cell bodies. See i. nucleus.

intermedius (in-ter-me′de-us) [TA]
SYN: intermediate (4) . [L.]

intermembranous (in-ter-mem′bra-nus)
Between membranes.

intermeningeal (in′ter-me-nin′je-al)
Between the meninges.

intermenstrual (in-ter-men′stroo-al)
Between two consecutive menstrual periods.

intermetacarpal (in-ter-met′a-kar′pal)
Between the metacarpal bones.

intermetameric (in′ter-met′a-mer′ik)
Between two metameres; denoting especially the intervertebral disks.

intermetatarsal (in-ter-met′a-tar′sal)
Between the metatarsal bones.

intermetatarseum (in-ter-met′a-tar′se-um)
SYN: os i..

intermission (in-ter-mish′un)
1. A temporary cessation of symptoms or of any action. 2. An interval between two paroxysms of a disease, such as malaria. [L. intermissio, fr. intermitto, to leave off, intermit, fr. mitto, to send]

intermit
To cease for a time.

intermittence, intermittency (in-ter-mit′ens, -en-se)
1. A condition marked by intermissions or interruptions in the course of a disease or other process or state or in any continued action; denoting especially a loss of one or more pulse beats. 2. Complete cessation of symptoms between two periods of activity of a disease.

intermittent (in-ter-mit′ent)
Marked by intervals of complete quietude between two periods of activity.

intermuscular (in-ter-mus′ku-lar)
Between the muscles.

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