Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Several antitumor substances that effectively inhibited the growth of ascites and solid tumor cells transplanted in mice were isolated from pine cone NaOH extract by acid- and ethanol-precipitation. These antitumor substances were also potent antiviral agents against human immunodeficiency virus, herpes simplex virus and influenza virus; they induced antimicrobial activity against Staphylococcal aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Candida albicans, and induced antiparasite activity against Hymenolepis nana in mice. Chemical analysis of these substances by IR, UV, NMR, ESR and partition chromatography on cellulose-TLC plate disclosed that they had lignin-related structures complexed with sugars or polysaccharides. Chlorinated decomposition of the lignin portion significantly reduced their antiviral activity. In agreement with this, the antiviral activity of synthesized lignins prepared by polymerization of phenylpropanoid precursors was comparable to that of the undecomposed counterparts of the pine cone extract. Acid hydrolysis of the polysaccharide portion significantly reduced the ability of the substances to induce antitumor and antimicrobial activities in mice. With an appropriate eliciting agent, intravenous administration of natural lignified substances transiently induced endogenous production of a cytotoxic factor (possibly tumor necrosis factor) in normal mice. Their priming activity was significantly higher than that of their component units or degradation products. These data suggest the importance of conjugating lignins with polysaccharides for in vivo expression of various kinds of immunopotentiating activity. As possible explanations for their induction of a variety of immunopotentiating activities, these natural and synthetic lignins stimulated macrophage NBT-reducing activity, polymorphonuclear cell (PMN) iodination and splenocyte DNA synthesis and inhibited poly (ADP-ribose) glycohydrolase, RNA-dependent DNA polymerase (reverse transcriptase) and RNA-dependent RNA polymerase activities.
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PMID:Antitumor, antiviral and immunopotentiating activities of pine cone extracts: potential medicinal efficacy of natural and synthetic lignin-related materials (review). 164 35

Crude extracts of dried leaves of Hyssop officinalis showed strong anti-HIV activity as measured by inhibition of syncytia formation, HIV reverse transcriptase (RT), and p17 and p24 antigen expression, but were non-toxic to the uninfected Molt-3 cells. Ether extracts from direct extraction (Procedure I), after removal of tannins (Procedure II), or from the residue after dialysis of the crude extract (Procedure III), showed good antiviral activity. Methanol extracts, subsequent to ether, chloroform and chloroform ethanol extractions, derived from procedure I or II, but not III, also showed very strong anti-HIV activity. In addition, the residual material after methanol extractions still showed strong activity. Caffeic acid was identified in the ether extract of procedure I by HPLC and UV spectroscopy. Commercial caffeic acid showed good antiviral activity in the RT assay and high to moderate activity in the syncytia assay and the p17 and p24 antigen expression. Tannic acid and gallic acid, common to other teas, could not be identified in our extracts. When commercial products of these two acids were tested in our assay systems, they showed high to moderate activity against HIV-1. Hyssop officinalis extracts contain caffeic acid, unidentified tannins, and possibly a third class of unidentified higher molecular weight compounds that exhibit strong anti-HIV activity, and may be useful in the treatment of patients with AIDS.
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PMID:Inhibition of HIV replication by Hyssop officinalis extracts. 170 26

We have developed a sensitive, PCR-based method for quantitating changes in mRNA levels of members of gene families. In this approach, total mRNA is converted to cDNA and then PCR is carried out on family members simultaneously, using primers derived from regions conserved among family members. This is followed by gel electrophoresis and blotting of the product to filters. The level of expression of individual family members is determined by separate hybridizations using probes unique for each member and derived from sequences between the PCR primers. In this manner the same aliquot of mRNA, the same reverse transcriptase reaction, PCR, gel electrophoresis, and denaturation and blotting are used for analysis of each family member. Thus, experimental variation is minimized, and changes in mRNA levels of family members relative to one another can be monitored with precision. In addition, if a family member is known not to change as a result of the treatment employed, this mRNA can be used to normalize the data from other members and thereby allow individual variations to be quantitated. We have applied this approach to members of the GABAA receptor subunit gene family and studied effects of chronic ethanol treatment on mRNAs corresponding to several GABAA receptor subunits.
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PMID:A general method for quantitative PCR analysis of mRNA levels for members of gene families: application to GABAA receptor subunits. 131 Apr 13

Effects of cell fixation procedures appropriate for flow cytometric analysis on the infectivity of human T lymphoblastoid H9 cells infected with human immunodeficiency virus-1 (HIV-1) were evaluated to provide guidelines for choosing cell treatments for potentially infectious samples. H9 cells experimentally infected with HIV-1 were treated by the test fixation procedure, washed, and cocultured with equal numbers of live, uninfected H9 cells. To estimate the reduction in infectivity due to the fixation procedure, dilution series of live infected H9 cells in uninfected H9 cells were simultaneously established in culture. Cell cultures were incubated 8-10 d, harvested, and evaluated for evidence of HIV-1 infection by the presence of cell-associated HIV-1 antigens and/or by the presence of particle-associated reverse transcriptase activity in cell culture supernatants. Thirty-minute fixation with formaldehyde (1.85%), methanol (absolute), methanol:acetone (1:1), or paraformaldehyde (0.5%) reduced the infectivity of HIV-1-infected H9 cells by greater than 99.99%. To the same degree, a multi-step fixation procedure utilizing formaldehyde and ethanol was effective in reducing HIV-1 infectivity. Conversely, the erythrocyte fixative dimethylsuberimidate at 3 micrograms/ml was ineffective in reducing HIV-1 infectivity.
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PMID:Effects of cellular fixatives on human immunodeficiency virus production. 237 57

We studied the inactivation of the etiologic agent of the acquired immunodeficiency syndrome, human immunodeficiency virus, in the course of the Kistler and Nitschmann cold ethanol fractionation of human blood plasma. By measuring reverse transcriptase activity and viral infectivity, we have shown that the virus load is reduced by a factor of 10(4) during the initial and at least a factor of 10(6) during the subsequent steps of the fractionation procedure. This loss of virus may be observed in the absence or in the presence of antibodies against human immunodeficiency virus and is due to a combination of chemical inactivation, physical partition, and injury caused by repeated freezing and thawing. The laboratory data therefore further confirm epidemiological studies which indicate that immunoglobulin preparations obtained by ethanol fractionation do not transmit human immunodeficiency virus.
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PMID:Inactivation and partition of human immunodeficiency virus during Kistler and Nitschmann fractionation of human blood plasma. 245 74

An extract of culture medium of Lentinus edodes mycelia (LEM) was prepared. This was further fractionated by 50% ethanol precipitation and both the resulting product, E-P-LEM, and LEM were studied to evaluate their effect on the activity of human immunodeficiency virus (HIV) in vitro. The experiments were performed using either a cell-free infection system with MT-4 cells, or a cell-to-cell infection system with MOLT-4 cells, which induces multinucleated giant cells very efficiently. E-P-LEM almost completely blocked both the cytopathic effect of giant cell formation and specific antigen expression due to HIV, whereas LEM before ethanol precipitation blocked the expression of HIV antigen in MT-4 cells only at a high concentration. Pretreatment of the virus with E-P-LEM before infection blocked HIV infection in the target cells. Thus, the inhibitory effect of LEM and E-P-LEM on HIV could be due to a blocking of the initial stages of HIV infection. Moreover, reverse transcriptase activity of avian myeloblastosis virus was inhibited.
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PMID:Inhibition (in vitro) of replication and of the cytopathic effect of human immunodeficiency virus by an extract of the culture medium of Lentinus edodes mycelia. 317 37

The RNA-dependent DNA polymerase of Rous sarcoma virus is inhibited by N-methyl isatin beta-thiosemicarbazone and by thiosemicarbazide, but not by semicarbazide. These inhibitors also inactivate, upon contact with the virion, the transforming ability of Rous sarcoma virus. Sulfhydryl donors, such as 2-mercapto-ethanol, can prevent these effects. The RNA-directed activity of the purified polymerase is inhibited to a greater degree than is the DNA-directed activity. Two cations, Cu(++) and Hg(++), can inhibit RNA-dependent DNA polymerase and inactivate the transforming ability of the virus. Synergism between N-methyl isatin beta-thiosemicarbazone and Cu(++) occurs, since treatment of the virus with a low dose of either N-methyl isatin beta-thiosemicarbazone or Cu(++) has little effect; however, when the two compounds are mixed together, significant inactivation occurs. This observation supports the hypothesis that the antiviral action of thiosemicarbazones is a function of their ability to act as a ligand for metallic ions. Several cations (Ag(+), Co(++), Zn(++), Cd(++), and Ni(++)) significantly inactivate the RNA-dependent DNA polymerase, but have little effect on the transforming ability. In view of this result, the conclusion that the enzyme activity is required for transformation remains open to question.
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PMID:Inhibition of RNA-dependent DNA polymerase of Rous sarcoma virus by thiosemicarbazones and several cations. 411 22

The molecular mechanisms that underlie ethanol dependence appear to involve alterations in GABAA receptor function and gene expression. In rat cerebral cortex, chronic exposure to ethanol alters many functional properties of GABAA receptors, including reduction of GABAA receptor-mediated chloride uptake. These functional alterations occur without a concomitant alteration in total receptor density or affinity. Previous investigations have shown that chronic ethanol exposure elicits alterations in mRNA and polypeptide levels for several abundant GABAA receptor subunits. For example, alpha 1 and alpha 2 subunit mRNA and polypeptide levels have been shown to decrease with chronic ethanol exposure. The present study was undertaken to further investigate the effects of chronic ethanol consumption on GABAA receptor subunit mRNA levels in rat cerebral cortex by using a competitive, quantitative reverse transcriptase-polymerase chain reaction assay that incorporates subunit-specific internal standards and allows for the absolute quantification of mRNA levels. We find that chronic ethanol consumption elicits a significant increase in alpha 4 subunit mRNA levels that is equal, in absolute amount, to a decrease in alpha 1 subunit mRNA levels. There is a small (30%) increase in gamma 2S but not gamma 2L subunit mRNA levels after chronic ethanol consumption. In addition, gamma 1 subunit mRNA levels are increased by 70%, whereas alpha 5, beta 1, beta 2, beta 3, gamma 3, and delta subunit mRNA levels do not change. We also reproduced results obtained previously by Northern blot analysis showing a 40% reduction in alpha 1 mRNA levels with no change in beta 2 subunit mRNA levels after chronic ethanol consumption. These results are consistent with the hypothesis that chronic ethanol consumption alters the function of GABAA receptors by eliciting changes in receptor subunit assembly. These changes may underlie the development of ethanol dependence.
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PMID:Chronic ethanol consumption differentially alters the expression of gamma-aminobutyric acidA receptor subunit mRNAs in rat cerebral cortex: competitive, quantitative reverse transcriptase-polymerase chain reaction analysis. 747 17

To determine the effect of disinfectants against viruses in vitro, I devised the Micro-Carrier-Test of dry-fixed virus-infected cells. Human immunodeficiency virus type 1-infected Molt-4 cells (1 x 10(5) cells in 5 microliters of 10% fetal bovine serum) were dry-fixed at the bottom of each well of a 96-well flat-bottomed microtiter plate for 120 minutes at room temperature. Disinfectants were added and allowed to remain for designated times and the wells were washed three times with PBS. Uninfected Molt-4 cells (1 x 10(4) cells/well) were inoculated and cultured for 4 weeks. The culture supernatant was harvested to measure reverse transcriptase activity by non-radioisotopic reverse transcriptase assay every week. Residual cytotoxicity of the disinfectant was determined by cytotoxicity assay. To evaluate the new method, the virucidal efficacy of several well-known disinfectants was reevaluated. Dose- and time-dependent effects of the disinfectants were determined. The minimal effective concentrations after 5 minutes of contact were 20% ethanol, 0.01% glutaraldehyde and 0.1% sodium hypochlorite. These results are almost the same as those reported previously, but there are some discrepancies. The differences between the present and previous protocols are discussed. This Micro-Carrier-Test promises to be useful in the screening of disinfectants.
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PMID:Micro-carrier-test: evaluating disinfectants for HIV. 749 18

Alcohol abuse increases the incidence and severity of opportunistic lung infections and pneumonias. Inducible nitric oxide (NO) synthase (iNOS II) and NO may be a pivotal system in the intracellular bactericidal activity of macrophages. We tested the hypothesis that acute administration of ethanol (ETOH) suppressed Escherichia coli endotoxin lipopolysaccharide (LPS) mediated upregulation of the iNOS II system in the lung of the rat, in vivo. We also tested the effect of ETOH on alveolar macrophage (AM) production of free NO using microelectrodes. Male Sprague-Dawley rats were given ETOH (5.5 g/kg, IP) 30 min. before giving intratracheal sterile phosphate buffered saline solution (PBS, 0.5 ml) or LPS (1 mg/kg in a total volume of 0.5 ml PBS). The isolated lungs were subjected to bronchoalveolar lavage (BAL) 3.5 hr. later. Aliquots of the BAL fluid were assayed for tumor necrosis factor alpha TNF alpha and reactive nitrogen intermediates (nitrate and nitrite) (RNI) with chemiluminescence. Aliquots of AM were incubated 1 hr ex vivo for spontaneous production of RNI or frozen and assayed for iNOS II mRNA with competitor exchange reverse transcriptase polymerase chain reaction (cERT-PCR). The lung was homogenized and assayed for RNI. LPS increased BAL fluid TNF alpha and RNI, lung RNI, and the spontaneous production of RNI by AM, ex vivo. These effects were inhibited by in vivo administration of inhibitors of iNOS II. LPS increased iNOS mRNA in AM. This was unaffected by iNOS inhibitors. ETOH suppressed LPS-induced BAL fluid TNF, iNOS mRNA and RNI production by AM and the lung.(ABSTRACT TRUNCATED AT 250 WORDS)
Alcohol
PMID:Ethanol suppresses LPS-induced mRNA for nitric oxide synthase II in alveolar macrophages in vivo and in vitro. 753 15


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