| anti-DNAse B | This is a serologic blood test used to detect antibodies against antideoxyribonuclease B (anti-DNAse B), an antigen that is produced by group A streptococci. This test is used to document a previous streptococcal infection in those who are suspected of having post-streptococcal disease (for example acute glomerulonephritis, rheumatic fever). A normal value is a negative assay. In adults this is less than 85 Todd units /ml. In school-age children this is less than 170 Todd units/ml. In pre-schoolers this is less than 60 Todd units/ml. Anywhere from 70 to 80% of people with rheumatic fever or post-streptococcal acute glomerulonephritis will have elevated anti-DNAse B levels. The test is performed on a venipuncture specimen. (27 Sep 1997) |
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| DNAse | <enzyme> An endonuclease with preference for DNA. Pancreatic DNAse I yields di and oligo nucleotide 5_ phosphates, pancreatic DNAse II yields 3_ phosphates. In chromatin, the sensitivity of DNA to digestion by DNAse I depends on its state of organisation, transcriptionally active genes being much more sensitive than inactive genes. Acronym: DNAase (10 Nov 1998) |
| DNAse footprinting | <molecular biology> A lab technique used to find out which segments of a DNA molecule are protected by DNA-binding proteins from attack by endonuclease enzymes, which break down DNA into smaller fragments by cleaving its phosphodiester bonds. The technique does this with gel electrophoresis to find out which parts of the DNA have sites for proteins to attach to them, by comparing DNA which has been in the presence of DNA-binding proteins with DNA that is pure. (09 Oct 1997) |
| DNAse i | A type of endonuclease, or enzyme that breaks down DNA molecules at their phosphodiester bonds. It is found in large quantities in the pancreas. (09 Oct 1997) |
| DNAse i hypersensitivity site | <molecular biology> A site on a DNA molecule that is especially prone to being cut apart by the endonuclease enzyme DNase I, which breaks down DNA into smaller fragments by cleaving phosphodiester bonds. These sites tend to be near active genes, which are regularly transcribed. (09 Oct 1997) |
| DNAse i sensitivity | <molecular biology> The likelihood that a particular DNA segment will be attacked by the endonuclease enzyme DNase I, which breaks down DNA into smaller fragments by cleaving its phosphodiester bonds. DNA segments which contain active genes that are regularly transcribed are more prone to being cut apart by DNase I than inactivated genes, because the inactivated genes are generally within condensed regions of the chromosome, while the active genes are in more open configurations for easy access for transcription. (09 Oct 1997) |
| agar | <cell culture, chemical, microbiology> This gelatinous material, an extract from red algae (mainly Gelidium and Gracilaria species), is most frequently used as a culture medium, especially for bacteria. It is also used as a thickener in foods, but humans cannot digest it. (06 May 1997) |
| agar-gel reaction | <immunology> The reaction between an antibody and an antigen during an immunology lab procedure where the two are allowed to diffuse toward each other through an agar-gel medium. Lines of precipitation form in the places on the gel where the two react with each other and shows where the reaction has occurred. (09 Oct 1997) |
| ascitic agar | A form of serum agar. (05 Mar 2000) |
| bile salt agar | An agar medium containing lactose, peptone, sodium taurocholate, and neutral red, for the growth and isolation of Gram-negative rods. (05 Mar 2000) |
| birdseed agar | Media prepared from Guizottia abyssinica seeds used in culturing and in the presumptive diagnosis of Cryptococcus neoformans. (05 Mar 2000) |
| blood agar | <cell culture> An agar-based medium which hasbeen enriched with sterilised, defibinated blood (sheep, rabbit or horse). It is used for primary plating andsubculturing, especially to determine bacterial haemolysis. (09 Oct 1997) |
| Bordet-Gengou potato blood agar | Glycerine-potato agar with 25% of blood, used for the isolation of Bordetella pertussis. (05 Mar 2000) |
| brain-heart infusion agar | A medium used for the isolation of fastidious microorganisms, especially fungi. (05 Mar 2000) |
| brilliant green salt agar | A highly selective culture medium consisting of agar with peptone, lactose, sodium taurocholate, brilliant green, and picric acid solution used in the primary isolation of enteric pathogens such as Salmonella species. (05 Mar 2000) |