| hybridism | The state of being hybrid. (05 Mar 2000) |
|---|---|
| hybridization | <molecular biology> The process of joining two complementary strands of DNA or one each of DNA and RNA to form a double-stranded molecule. Technique in which single stranded nucleic acids are allowed to interact so that complexes or hybrids, are formed by molecules with sufficiently similar, complementary sequences. By this means the degree of sequence identity can be assessed and specific sequences detected. The hybridisation can be carried out in solution or with one component immobilised on a gel or, most commonly, nitrocellulose paper. Hybrids are detected by various means: visualisation in the electron microscope, by radioactively labelling one component and removing noncomplexed DNA or by washing or digestion with an enzyme that attacks single stranded nucleic acids and finally estimating the radioactivity bound. Hybridisations are done in all combinations: DNA DNA (DNA can be rendered single stranded by heat denaturation), DNA RNA or RNA RNA. In situ hybridisations involve hybridising a labelled nucleic acid (often labelled with a fluorescent dye) to suitably prepared cells or histological sections. This is used particularly to look for specific transcription or localisation of genes to specific chromosomes (FISH analysis). <zoology> The mating of individuals from different species or sub-species. (13 Oct 1997) |
| hybridoma | <cell culture, tumour> A cell hybrid in which a tumour cell forms one of the original source cells. In practice, confined to hybrids between T or B lymphocytes and appropriate myeloma cell lines. (13 Oct 1997) |
| hybridomas | Cells artificially created by fusion of activated lymphocytes with neoplastic cells. The resulting hybrid cells are cloned and produce pure or "monoclonal" antibodies or T-cell products, identical to those produced by the immunologically competent parent, and continually grow and divide as the neoplastic parent. (12 Dec 1998) |
| hycanthone | <chemical> Potentially toxic, but effective antischistosomal agent, it is a metabolite of lucanthone. Pharmacological action: schistosomicides. Chemical name: 9H-Thioxanthen-9-one, 1-((2-(diethylamino)ethyl)amino)-4-(hydroxymethyl)- (12 Dec 1998) |
| HycI protease | <enzyme> Involved in maturation of hyce from e. Coli. Registry number: EC 3.4.99.- (26 Jun 1999) |
| hyclate | USAN-approved contraction for monohydrochloride hemiethanolate hemihydrate, HCl-1/2C2H5OH-1/2H2O. (05 Mar 2000) |
| hydantoic | <chemistry> Pertaining to, or derived from, hydantoin. See Glycoluric. Source: Websters Dictionary (01 Mar 1998) |
| hydantoin | <chemistry> A derivative of urea, C3H4N2O2, obtained from allantion, as a white, crystalline substance, with a sweetish taste. Synonym: glycolyl urea. Origin: Hydrogen + allantion. Source: Websters Dictionary (01 Mar 1998) |
| hydantoin racemase | <enzyme> Catalyses the racemization of 5-substituted hydantoins in pseudomonas to their corresponding n-carbamoyl amino acids and ultimately to the corresponding l-amino acid Registry number: EC 5.1.99.- Synonym: hyue protein, hyue gene product (26 Jun 1999) |
| hydantoinate | A salt of hydantoin. (05 Mar 2000) |
| hydathode | An epidermal structure specialised for secretion, or for exudation, of water. (09 Oct 1997) |
| hydatid | <zoology> A membranous sac or bladder filled with a pellucid fluid, found in various parts of the bodies of animals, but unconnected with the tissues. It is usually formed by parasitic worms, especially. By larval tapeworms, as Echinococcus and Coenurus. See these words in the Vocabulary. <anatomy> Hydatid of Morgagni, one of the small pedunculated bodies found between the testicle and the head of the epididymis, and supposed to be a remnant of the Mullerian duct. Origin: Gr, a watery vesicle under the upper eyelid, fr. "ydwr, "ydatos, water: cf. F. Hydatide. Source: Websters Dictionary (01 Mar 1998) |
| hydatid cyst | A cyst formed in the liver, or, less frequently, elsewhere, by the larval stage of Echinococcus, chiefly in ruminants; two morphological forms caused by Echinococcus granulosus are found in humans: the unilocular hydatid cyst and the osseous hydatid cyst; a third form in humans is the alveolar hydatid cyst, caused by Echinococcus multilocularis. Synonym: echinococcus cyst, hydatid. (05 Mar 2000) |
| hydatid cyst of morgagni | <radiology> Paraovarian cyst near fimbria or broad ligament, serous fluid, no clinical significance, wolffian duct remnant (probably) (12 Dec 1998) |