Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The purpose of this investigation was to search for oncornavirus in primary cell cultures obtained from leukemic cattle organs and lymphocytes and to study their molecular-biological properties and role in the etiology of cattle leukemia. The investigation was carried out on 25 primary trypsinized cell culutres of lymph nodes, spleens, kidneys and lymphocytes from cattle with acute and chronic leukemia. It was demonstrated that all cell cultures from leukemic cattle (in contrast to cell cultures from healthy cattle) released oncornavirus into the culture medium. The virus possesses the main properties of oncornaviruses: it has a virion of C-type structure with a density of 1.16--1.18g/ml in a 20--60 per cent sucrose gradient, which may be induced by 5-bromodeoxyuridine, inhibited by Actino-mycin D, has reverse transcriptase activity, contains 60S RNA, that is annealed in the reaction of molecular hybridization with DNA of lymph nodes of cattle with leukemia. The propagation of the isolated oncornavirus in continuous cell lines of calf kidney culture was demonstrated. Experimental inoculation of purified oncornavirus was carried out on 60 baby calves and 15 lambs from leukosis free herds or flocks. Several of the calves later showed evidence of virus infection.
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PMID:Isolation and characterisation of oncornavirus from primary cultures of tissues from cattle with leukemia. 6 13

The number of genetic lesions necessary to generate leukemia in humans is unknown, but it is possible that certain specific abnormalities, eg, fusion genes, known to be associated with acute and chronic leukemia are produced relatively frequently in human cells but require other events to occur before the leukemia becomes manifest. We investigated this possibility by studying peripheral blood leukocytes from normal individuals and various hematopoietic cell lines for the presence and expression of the p210 and the p190 types of the BCR-ABL gene associated with chronic myeloid leukemia (CML) and acute lymphoblastic leukemia. We used two-step reverse transcriptase-polymerase chain reaction (RT-PCR) assays in which batches of 10(8) cells per sample were tested in 40 replicate reactions. We estimate that this assay is 1.5 logs more sensitive than the two-step RT-PCR assays that we use routinely to assess minimal residual disease. BCR-ABL fusion gene transcripts of various configurations were found in circulating leukocytes from 12 of the 16 healthy adults analyzed. Transcripts with an e1a2 junction (p190 BCR-ABL) were present in 11 and p210-type transcripts with b2a2 and/or b3a2 junctions were detected in 4 individuals. The same RT-PCR assays in non-CML cell lines showed the presence of classical or aberrant p210-type mRNA in 3 of 7 lines and of p190-type transcripts in all 7 lines of hematopoietic origin (HL60, KG1, U937, Kasumi, Jurkat, JVM13, and JVM25), whereas the NIH3T3 murine fibroblast line was reproducibly negative for these fusion genes. These findings confirm and extend previous reports on the detection of leukemia-associated genes in normal leukocytes and suggest that certain fusion genes are generated relatively frequently in hematopoietic cells, but only infrequently do the cells acquire the additional changes necessary to produce leukemia in humans. Although there is only a small probability that such innocent BCR-ABL-carrying leukocytes are detected by conventional RT-PCR assays, they may be the source of some sporadically positive tests in leukemia patients in long-term remission.
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PMID:The presence of typical and atypical BCR-ABL fusion genes in leukocytes of normal individuals: biologic significance and implications for the assessment of minimal residual disease. 978 74