| reverse transcriptase md | <molecular biology> A viral enzyme that constructs DNA from an RNA template, which is an essential step in the life-cycle of a retrovirus such as HIV (09 Oct 1997) |
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| reverse transcriptase PCR | A technique used to amplify RNA targets. The specimen containing the target RNA (e.g., HIV-1 RNA, Hepatitis C Virus RNA) is subjected to reverse transcription to make complementary DNA (cDNA), which is then, in turn, amplified by PCR. Acronym: RT-PCR (05 Mar 2000) |
| reverse transcription | <molecular biology> The process of copying information found in RNA into DNA. (09 Oct 1997) |
| reverse transcriptons | An enzyme that converts RNA to DNA. Some viruses have only RNA as their primary genetic material. By converting their RNA genes to DNA with this enzyme, the host cell is 'tricked' into creating new copies of the virus. Useful in genetic engineering to make DNA from mRNA. (14 Nov 1997) |
| reverse Trendelenburg position | Supine position without flexing or extending, in which the head is higher than the feet. (05 Mar 2000) |
| HIV-1 reverse transcriptase | <enzyme> HIV-1 enzyme responsible for the synthesis of DNA from genomic RNA of the virus. It is encoded by the pol gene of HIV-1. Registry number: EC 2.7.7.- (12 Dec 1998) |
| HIV-2 reverse transcriptase | <enzyme> Responsible for synthesis of double-stranded DNA from the genomic RNA of the virus; has rnase h and DNA-dependent DNA polymerase activities; was indexed as reverse transcriptase (87-91) Registry number: EC 2.7.7.- (26 Jun 1999) |
| DNA reverse gyrase | <enzyme> A topoisomerase II subclass which introduces positive superhelical turns into DNA Registry number: EC 3.1.- Synonym: reverse gyrase (26 Jun 1999) |
| triiodothyronine, reverse | <chemical> 0-(4-hydroxy-3,5-diiodophenyl)-3-iodo-l-tyrosine. A metabolite of thyroxine formed by the peripheral degradation of thyroxine as a result of the tyrosyl or inner ring 5-deiodination. In systemic disease states or in neonates, levels of triiodothyronine are low and those of reverse triiodothyronine are elevated. Reverse t3 is therefore useful as a diagnostic aid and in the treatment of foetal and infantile hypothyroidism. Chemical name: L-Tyrosine, O-(4-hydroxy-3,5-diiodophenyl)-3-iodo- (12 Dec 1998) |
| abscopal effect | A reaction produced following irradiation but occurring outside the zone of actual radiation absorption. (05 Mar 2000) |
| additive effect | <biochemistry, chemistry> An additive effect is the overall biological effect two chemicals acting together and which is the simple sum of the effects of the chemicals acting independently. Compare: antagonism. (15 Jan 1998) |
| adverse effect | This is an abnormal or harmful effect to an organism caused by exposure to a chemical. It is indicated by some result such as death, a change in food or water consumption, altered body and organ weights, altered enzyme levels, or visible illness. An effect may be classed as adverse if it causes functional or anatomical damage, causes irreversible change in the homeostasis of the organism, or increases the susceptibility of the organism to other chemical or biological stress. A non-adverse effect will usually be reversed when the organism is no longer being exposed to the chemical. (09 Oct 1997) |
| Anrep effect | A small transient positive inotropic effect of abrupt increases of systolic aortic and left ventricular pressures related to recovery from transient subendocardial ischemia (e.g., cold pressor test). (05 Mar 2000) |
| antagonistic effect | This is the consequence of one chemical (or group of chemicals) counteracting the effects of another chemical, the opposing chemicals cancel out each other's effects. (09 Oct 1997) |
| Arias-Stella effect | Focal, unusual, decidual changes in endometrial epithelium, consisting of intraluminal budding, and nuclear enlargement and hyperchromatism with cytoplasmic swelling and vacuolation; may be associated with ectopic or uterine pregnancy. Synonym: Arias-Stella effect, Arias-Stella reaction. (05 Mar 2000) |