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)

Twenty different isolates of the soil bacterium Myxococcus xanthus were examined for the presence of multicopy single-stranded DNA (msDNA)-producing retroelements, or retrons. Each strain was analyzed by ethidium bromide staining for msDNA, 32P labeling of the msDNA molecule by the reverse transcriptase (RT) extension method, and DNA hybridization experiments with probes derived from two retrons, Mx162 and Mx65, previously cloned from M. xanthus DZF1. These analyses revealed that all M. xanthus strains contain an msDNA very similar to Mx162 msDNA, and 13 strains also contain a second smaller msDNA very similar to Mx65 msDNA. In addition, the strains contained retron-encoded genes msr and msd, which code for msDNA, and a gene for RT responsible for the synthesis of msDNA. These genes show greater than 80% nucleotide sequence similarity to retrons Mx162 or Mx65. The near-ubiquitous occurrence of msDNA retrons among M. xanthus strains and their homogeneous nature are in marked contrast to the highly diverse but rarely occurring msDNA-producing elements of Escherichia coli. The possible origin and evolution of RT and retron elements is discussed in view of these findings.
J Bacteriol 1991 Sep
PMID:Survey of multicopy single-stranded DNAs and reverse transcriptase genes among natural isolates of Myxococcus xanthus. 171 54

The transmission of human immunodeficiency virus (HIV) by blood or blood components is a major concern in blood banking. A photodynamic flow cell system was designed to inactivate cell-free HIV mixed with blood from a healthy donor. Blood containing 4 x 10(3) infectious units of HIV was treated with 10 and 20 micrograms per mL of commercially available dihematoporphyrin ether (DHE) per mL. Aliquots of this mixture were then held in the dark or irradiated in a flow cell illuminated at a light energy density of 5 J per cm2 provided by a xenon light source equipped with a 630 +/- 5 nm band-pass interference filter; the aliquots were subsequently placed in A.301 cells. All infected cultures were assessed for reverse transcriptase (RT) activity for 17 days. RT activity for either concentration of dye was significantly reduced in irradiated samples as compared to that in samples held in the dark. Blood samples from volunteers also were assessed for the effects of the inactivation process on red cells at concentrations of DHE up to 200 micrograms per mL. No effects were observed on red cell 2,3 DPG or ATP, whole blood potassium concentrations, red cell osmotic fragility, or blood cell antigens.
Transfusion 1991 Sep
PMID:Preliminary studies of photoinactivation of human immunodeficiency virus in blood. 171 85

Recently, we reported that hepatitis C virus (HCV) can be classified genetically into two types, HCV-K1 and HCV-K2, which show 67% and 71% identity at the nucleotide and amino acid sequence levels in a 340 bp region which encodes the NS5 gene Gly-Asp-Asp motif. To develop a rapid method to classify the genomes of HCV isolates, we identified restriction fragment length polymorphisms (RFLPs) in reverse transcriptase-polymerase chain reaction products encoding a portion of the NS5 gene. AluI and AccII enabled HCV to be classified into the K1 and K2 types, and Sau96I enabled classification into the K1 type, and the K2a and K2b subtypes. These RFLPs also generally allow Japanese isolates to be distinguished from the prototype (PT, an isolate from the U.S.A.), which is a K1 type. Sequence analysis of the 5'-untranslated regions of Japanese isolates revealed near identity between the K1 type and PT, and 93 to 94% identity between the K1 and K2 types, indicating that there are type K1- and K2-specific RFLPs in this region. Our results suggest that the nucleotide sequences of the K1 and K2 types are different throughout the HCV genome. The incidence of HCV types K1, K2a and K2b, and PT in 50 samples was 74%, 16%, 8% and 2%, respectively.
J Gen Virol 1991 Sep
PMID:Typing of hepatitis C virus genomes by restriction fragment length polymorphism. 171 52

Serial human immunodeficiency virus type-1 (HIV-1) isolates were obtained from five individuals with acquired immunodeficiency syndrome (AIDS) who changed therapy to 2',3'-dideoxyinosine (ddI) after at least 12 months of treatment with 3'-azido-3'-deoxythymidine (zidovudine, AZT). The in vitro sensitivity to ddI decreased during the 12 months following ddI initiation, whereas AZT sensitivity increased. Analysis of the reverse transcriptase coding region revealed a mutation associated with reduced sensitivity to ddI. When this mutation was present in the same genome as a mutation known to confer AZT resistance, the isolates showed increased sensitivity to AZT. Analysis of HIV-1 variants confirmed that the ddI resistance mutation alone conferred ddI and 2',3'-dideoxycytidine resistance, and suppressed the effect of the AZT resistance mutation. The use of combination therapy for HIV-1 disease may prevent drug-resistant isolates from emerging.
Science 1991 Sep 27
PMID:Resistance to ddI and sensitivity to AZT induced by a mutation in HIV-1 reverse transcriptase. 171 88

A reverse transcriptase-polymerase chain reaction (RT-PCR) method was adopted for detecting transcripts specific for retTPC/PTC, an activated form of the ret proto-oncogene reported to be found specifically in human papillary thyroid carcinomas. By this sensitive method retTPC/PTC transcript could be detected in about 500 fg of total RNA of TPC-1, a retTPC/PTC transcript-positive cell line. In Japanese patients, one of 11 papillary thyroid carcinomas, four of 19 follicular adenomas and one of two adenomatous goiters were positive for the transcript, indicating that the involvement of retTPC/PTC is not specific to papillary thyroid carcinomas. In several independent RT-PCR experiments using different portions of the same positive carcinoma tissue, retTPC/PTC transcript was always detected. On the other hand, the transcript was not always positive in different RNA samples from benign cases, suggesting that positive carcinomas are probably composed of clonal cell populations all expressing retTPC/PTC, whereas adenomas and adenomatous goiter comprise heterogeneous populations: both positive and negative for retTPC/PTC transcript. Activation of the ret proto-oncogene might therefore be involved in malignant conversion to thyroid carcinomas.
Oncogene 1991 Sep
PMID:Detection of retTPC/PTC transcripts in thyroid adenomas and adenomatous goiter by an RT-PCR method. 171 26

A rapid and simple protocol for the isolation of RNA from transfected tissue culture cells is described. The protocol employs a guanidinium thiocyanate/phenol mixture to lyse cells directly from tissue culture plates and extract the total RNA. A total of six simple steps, which can be accomplished within 2.5 hours, are required. The protocol reproducibly yields 20-40 micrograms RNA from 0.5 x 10(6) - 1 x 10(6) cells per sample. The quality of the RNA obtained is sufficient for reverse transcriptase assays such as oligonucleotide-directed primer extension and random-primed cDNA synthesis.
Biotechniques 1991 Sep
PMID:Rapid, small-scale RNA isolation from tissue culture cells. 171 28

Human promonocyte cells chronically infected with human immunodeficiency virus type (HIV-1) (clone U1.1.5) were grown in the presence of media conditioned by human astrocytes and glioma cell lines U251 and 253. HIV-1 expression was assessed by measuring reverse transcriptase activity. All media conditioned by unstimulated and lipopolysaccharide (LPS) stimulated glial cells induced HIV-1 expression and contained detectable levels of interleukin-6 (IL-6) but not tumor necrosis factor-alpha (TNF-alpha). An antibody against IL-6, but not against TNF-alpha, reduced the induction of HIV-1 by the conditioned media in a concentration-dependent manner. The magnitude of HIV-1 induction by the conditioned media was proportional to the concentration of IL-6 in them. The data indicate that normal and transformed human astrocytes are capable of stimulating HIV-1 expression in chronically infected promonocytic cells by secreting IL-6. The results demonstrate that cytokines secreted by neural cells could play an important role in regulating HIV-1 expression in the brain.
AIDS Res Hum Retroviruses 1991 Sep
PMID:Human astrocytes stimulate HIV-1 expression in a chronically infected promonocyte clone via interleukin-6. 174 78

In order to investigate how human immunodeficiency virus (HIV) gains entry to the placenta, we have performed in vitro experiments in which highly purified trophoblast cells isolated from term human placentas were examined for their susceptibility to HIV infection. Trophoblast cells were exposed to cell-free HIV-1 for up to 24 h, after which the cultures were monitored by p24 antigen capture assay, reverse transcriptase assay, and electron microscopy for evidence of virus uptake and replication. None was found. In the second series of experiments, trophoblast cells were cocultured with HIV-infected MOLT-4 cells for 24 h, stained using an anti-HIV antibody, and examined by immunofluorescence microscopy. The MOLT cells were strongly positive, as expected, but many trophoblast colonies also showed a punctate staining pattern. Examination of similar cultures using the electron microscope revealed MOLT cells adherent to trophoblast but no evidence of cell-cell fusion. Virions were observed in coated pits at the trophoblast cell surface and in endosomes or multivesicular bodies in the cytoplasm. These observations are consistent with an endocytosis-mediated mechanism of virus entry. Virions were also observed budding from the trophoblast plasma membrane, indicating that these cells can support HIV replication. To our knowledge, these results show for the first time that HIV can infect placental trophoblast cells in vitro. The results suggest that the placenta could become infected with HIV by the interaction of virus-infected maternal lymphocytes with syncytiotrophoblast bordering the maternal blood in the intervillous space.
AIDS Res Hum Retroviruses 1991 Sep
PMID:Cell-mediated infection of human placental trophoblast with HIV in vitro. 174 80

Fabry disease is an X-linked disorder accompanied with accumulation of glycosphingolipids resulting from the deficient activity of the lysosomal hydrolase, alpha-galactosidase A (alpha-GalA). In the present study, mRNA for alpha-GalA in fibroblasts from an 11-year-old Japanese patient with Fabry disease was examined using the reverse transcriptase-polymerase chain reaction (PCR). The shorter message of alpha-GalA was demonstrated in this patient when compared with the normal control. The complete deletion of exon 4 in the mRNA for alpha-GalA in the patient was disclosed by analysis of cDNA with restriction enzyme digestion and asymmetrical PCR sequencing. The direct sequencing of the genomic DNA demonstrated a single base substitution (G----A) at the 3' end of the consensus sequence of intron 3. This mutation destroyed a splice site in the alpha-GalA, which produced a mutant allele. It was also shown that the mother of the patient had this mutant as well as normal alleles as a heterozygote.
Jinrui Idengaku Zasshi 1991 Sep
PMID:A 3' splice site consensus sequence mutation in the intron 3 of the alpha-galactosidase A gene in a patient with Fabry disease. 175 37

Peripheral blood mononuclear cells (PBMC) from 13 asymptomatic healthy human immunodeficiency virus type-1 (HIV-1) antibody positive prostitutes from Tamil Nadu, southern India, were cocultivated with phytohemagglutinin stimulated PBMC from HIV antibody negative donors for HIV isolation. In addition, plasma samples from two antibody positive prostitutes with HIV antigenemia were processed for virus isolation. The presence of virus in the cultures was monitored by (i) assay for virus particle associated reverse transcriptase (RT) activity, (ii) HIV-antigen enzyme immunoassay, and (iii) indirect immunofluorescence test to detect expression of HIV specific core antigens p-24 and p-17 in infected cells using monoclonal antibodies to these antigens. The virus was isolated from PBMC from 2 prostitutes (86-4 and 86-5) and from plasma of one prostitute (86-20). These isolates have been characterised as HIV type-1 by dot blot hybridization using HIV-1 and HIV-2 proviral DNA probes.
Indian J Med Res 1991 Sep
PMID:Recovery of human immunodeficiency virus from asymptomatic prostitutes from Tamil Nadu. 177 12


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