|Medical Dictionary - Dictionary of Medicine and Human Biology|
Having all the axes alike, as a sphere. [G. homos, the same, + axis]
Sir Everard, English surgeon, 1756–1832. See H. lobe.
The same, alike. SEE ALSO: homo- (1) . [G. homoios, similar]
A highly conserved DNA sequence of about 180 base pairs near the 3′ end of specific homeotic genes; it encodes a DNA-binding domain that allows the h. proteins to bind to and regulate gene expression in development. SYN: homeodomain.
homeodomain (ho′me-o-do- man′)
Without change in size. [homeo- + G. metron, measure]
Of similar shape, but not necessarily of the same composition. [homeo- + G. morphe, shape]
1. Relating to homeopathy. SYN: homeotherapeutic (1) . 2. Denoting an extremely small dose of a pharmacologic agent that theoreticaly mimics the symptoms produced by the condition being treated, such as might be used in homeopathy; more generally, a dose believed to be too small to produce the effect usually expected from that agent. An alternative form of medicine to allopathic, in which drugs antagonize the effects of the disease. Cf.:pharmacologic (2) , physiologic (4) , supraphysiologic. [homeo- + G. pathos, disease]
A medical practitioner of homeopathy. SYN: homeopath.
A system of therapy developed by Samuel Hahnemann based on the “law of similia,” from the aphorism, similia similibus curantur (likes are cured by likes), which holds that a medicinal substance that can evoke certain symptoms in healthy individuals may be effective in the treatment of illnesses having similar symptoms, if given in very small doses [homeo- + G. pathos, suffering]
The formation of new tissue of the same character as that already existing in the part. SYN: homoioplasia. [homeo- + G. plasis, a molding]
Relating to or characterized by homeoplasia.
The set of processes by which imbalances and other defects in ontogeny are corrected before development is completed. SYN: ontogenic homeostasis, waddingtonian homeostasis. [homeo- + G. rheos, stream, current]
Formation of a body part having characteristics normally found in a related or homologous part at another location in the body. [homeo- + G. -osis, condition]
homeostasis (ho′me-o-sta′sis, -os′ta-sis)
1. The state of equilibrium (balance between opposing pressures) in the body with respect to various functions and to the chemical compositions of the fluids and tissues. 2. The processes through which such bodily equilibrium is maintained. [homeo- + G. stasis, standing] Bernard-Cannon h. the set of mechanisms responsible for the cybernetic adjustment of physiologic and biochemical states in postnatal life. SYN: physiologic h.. genetic h. SYN: Lerner h.. Lerner h. the restorative mechanisms that tend to correct perturbations in the genetic composition of a population. SYN: genetic h.. ontogenic h. SYN: homeorrhesis. physiologic h. SYN: Bernard-Cannon h.. waddingtonian h. SYN: homeorrhesis.
Relating to homeostasis.
1. SYN: homeopathic (1) . 2. Relating to homeotherapy.
homeotherapy, homeotherapeutics (ho′me-o-thar′a-pe, -thar-a-pu′tiks)
Treatment or prevention of a disease using the principles of homeopathy.
Any of the animals, including mammals and birds, that tend to maintain a constant body temperature. SYN: hematherm, warm-blooded animal. [homeo- + G. thermos, warm]
Pertaining to, or having the essential characteristic of, homeotherms. Cf.:poikilothermic, heterothermic. SYN: hemathermal, hemathermous, hematothermal, homeothermal, homoiothermal, homothermal, warm-blooded.
Pertaining to or characterized by homeosis.
Of or resembling the usual type.
Obsolete term for normal metabolism and its results. [G. homos, same, + ergon, work]
Having a tendency toward homicide.
The killing of one human being by another. [L. homo, man, + caedo, to kill]
homidium bromide (ho-mid′e-um)
A trypanocide used in veterinary medicine. SYN: ethidium.
The primate family, which includes modern humans (Homo sapiens) and several fossil groups.
A superfamily of the Primates including the anthropoid apes and humans. Divided into the families Pongidae (anthropoid apes) and Hominidae (humans). [L. homo (homin-), man, + G. eidos, form]
The genus of primates that includes humans. [L. man] H. sapiens modern human beings. [L. wise man]
1. Combining form meaning the same, alike; opposite of hetero-. SEE ALSO: homeo-. 2. In chemistry, prefix used to indicate insertion of one more carbon atom in a chain ( i.e., insertion of a methylene moiety). [G. homos, the same]
homoarginine (Har) (ho-mo-ar′ji-nen)
A homolog of arginine having an additional methylene group.
A compound resembling biotin except for the substitution of an oxygen atom for the sulfur and the presence of an additional CH2 group in the side chain; an active biotin antagonist.
Developing from a single type of tissue. [homo- + G. blastos, germ]
N2-(4-Aminobutyryl)-l-histidine;a constituent of the brain formed from l-histidine and γ-aminobutyric acid.
An inborn error in metabolism in which homocarnosine levels are elevated, particularly in the cerebral spinal fluid.
Having the same center; denoting rays that meet at a common focus. Cf.:heterocentric (1) .
1. SYN: synchronous. 2. Occurring at the same age in each generation. [homo- + G. chronos, time]
An inherited disorder associated with elevated urinary levels of homocitrulline.
Denoting an anastomosis between branches of the same arterial trunk, as distinguished from heterocladic. [homo- + G. klados, a branch]
homocysteine (Hcy) (ho-mo-sis′te-en, - sis′tin)
HSCH2CH2CH(NH3)+COO-;a homolog of cysteine, produced by the demethylation of methionine, and an intermediate in the biosynthesis of l-cysteine from l-methionine via l-cystathionine. Elevated levels of h. have been associated with certain forms of heart disease. SEE ALSO: folic acid.Elevation of the level of h. in the plasma is an independent risk factor for cardiovascular disease (including myocardial infarction, stroke, thromboembolic disease, and intermittent claudication) and (in pregnant women) for fetal neural tube defects such as spina bifida and anencephaly. An increased plasma total h. level has been reported to confer an independent risk of vascular disease similar to that of smoking or hyperlipidemia, and to compound the risk associated with smoking and hypertension. Approximately 25% of people with atherosclerosis are found to have elevation of plasma h. above 15 mmol/L. Because h. rises after myocardial infarction and remains elevated for months, some have questioned the causal role assigned to it in vascular disease. Several prospective studies have failed to establish a connection between h. levels and coronary disease risk. H. appears to exert a direct toxic effect on the intima of arteries, besides inducing oxidation of low-density lipoproteins and predisposing to thrombus formation by activating platelets and coagulation factors. In animal reproduction studies it promotes neural tube defects, cardiac anomalies, and failure of ventral closure. Elevation of plasma h. occurs in various conditions, including genetic disorders, nutritional deficiencies, and chronic diseases. The level is higher in men and tends to rise with advancing age. Premature cardiovascular disease was first linked to elevation of h. in people with homocystinuria, a rare genetic disorder in which deficiency of the enzyme cystathionine β-synthase leads to elevation of h. in plasma and of its oxidation product, homocystine, in urine. A more common genetic disorder associated with abnormally high levels of h. results from mutation of the gene that encodes the enzyme methylene tetrahydrofolate reductase. The marked increase in h. levels after menopause may play a role in the increased incidence of vascular disease, cancer, and osteoporosis in postmenopausal women. Dietary deficiency of folic acid, vitamin B6 (pyridoxine), and vitamin B12 is also associated with elevation of h., as are chronic renal failure, hypothyroidism, and some malignancies. Lowering the serum concentration of h. by administration of folic acid has been shown to reduce the risk of adverse cardiovascular events in people with homocystinuria. In animal studies, administration of folic acid prevents the teratogenic effect of h.. Screening for elevated h. levels is advised for people with coronary artery disease out of proportion to known risk factors, or for those with a family history of premature atherosclerotic disease. Administration of folic acid in a dose of 1 mg/day or more reduces h. levels nearly to normal and protects against both vascular disease and birth defects.
The disulfide resulting from the mild oxidation of homocysteine; an analog of cystine.
Presence of an excess of homocystine in the plasma, as in homocystinuria.
homocystinuria (ho′mo-sis-ti-noo′re-a) [MIM*236200]
A metabolic disorder characterized by sparse blond hair, long limbs, pectus excavatum, dislocation of lens, failure to thrive, mental retardation, psychiatric disturbances, and thromboembolic episodes; some patients have alleviation of symptoms with pyridoxine while others are not responsive; associated with increased urinary excretion of homocystine and methionine. Autosomal recessive inheritance, but carriers have an increased risk of occlusive vascular disease; caused by mutation in the cysthathione beta-synthase gene (CBS) on chromosome 21q. In addition, there are seven other causes of h.: (1) defect in vitamin B12 metabolism [MIM*277400], (2) deficiency of N-methylene-tetrahydrofolate reductase [MIM*236250], (3) selective intestinal malabsorption of vitamin B12 [MIM*261100], (4) vitamin B12 responsive h., cblE type [MIM*236270], (5) methylcobalamin deficiency, cblG type [MIM*250940], (6) vitamin B12 metabolic defect type 2 [MIM*277410], and (7) transcobalamin II deficiency [MIM*275350].
Having an affinity for cells of the same or a closely related species. [homo- + G. kytos, cell, + trope, a turning toward]
Having teeth all alike in form, as those of the lower vertebrates, in contrast to heterodont. [homo- + G. odous, tooth]
Moving in the same direction. [homo- + G. dromos, running]
homoerotism, homoeroticism (ho-mo-er′o-tizm, -e-rot′i-sizm)
SYN: homosexuality. [homo- + G. eros, love]
Producing only one type of gamete with respect to sex chromosomes; in humans and most animals, the female is h.. SYN: monogametic. [homo- + G. gametikos, connubial]
Similarity of husband and wife in a specific trait. [homo- + G. gamos, marriage]
Tissue ground into a creamy consistency in which the cell structure is disintegrated (so-called “cell-free”). Cf.:brei.
Of uniform structure or composition throughout. [homo- + G. genos, race]
Production of offspring similar to the parents, in contrast to heterogenesis. SYN: homogeny. [homo- + G. genesis, production]
The process by which a material is made homogeneous.
To make homogeneous.
Having a structural similarity because of descent from a common ancestor. Commonly confused with homogeneous. [homo- + G. genos, family, kind]
homogentisate 1,2-dioxygenase (ho-mo-jen′tis-at)
An iron-containing enzyme that catalyzes the oxidative cleavage of the benzene ring in homogentisic acid by O2, forming 4-maleylacetoacetate; an absence or deficiency of this enzyme will result in alcaptonuria. SYN: homogentisic acid oxidase.
homogentisic acid (ho′mo-jen-tis′ik)
Glycosuric acid; (2,5-dihydroxyphenyl)acetic acid;an intermediate in l-phenylalanine and l-tyrosine catabolism; if made alkaline, it oxidizes rapidly in air to a quinone that polymerizes to a melaninlike material; elevated levels are observed in individuals having alcaptonuria. SYN: alcapton, alkapton. h. oxidase SYN: homogentisate 1,2-dioxygenase.
A polysaccharide consisting of only one type of monosaccharide subunit ( e.g., glucan). Cf.:heteroglycan, glycan.
Genetically identical multiple nuclei in a common cytoplasm, usually resulting from fusion of two cells from the same species. [homo- + G. karyon, kernel, nut]
Exhibiting the properties of a homokaryon.
Corneal transplant between members of the same species.
SYN: ipsilateral. [homo- + L. latus, side]
Lipids containing only C, H, and O. Cf.:heterolipids. SYN: simple lipids.
homolog, homologue (hom′o-log)
A member of a homologous pair or series. [homo- + G. logos, word, ratio, relation]
Corresponding or alike in certain critical attributes. 1. In biology or zoology, denoting organs or parts corresponding in evolutionary origin and similar to some extent in structure, but not necessarily similar in function. 2. In chemistry, denoting a single chemical series, differing by fixed increments. 3. In genetics, denoting chromosomes or chromosome parts identical with respect to their construction and genetic content. 4. In immunology, denoting serum or tissue derived from members of a single species, or an antibody with respect to the antigen that produced it. 5. Proteins having identical or similar functions (particularly with respect to proteins from different species). [see homolog]
. . . Feedback