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)

To elucidate which neuropeptide Y receptor subtype is responsible for the neuropeptide Y-induced potentiation of the noradrenaline-evoked contraction in human omental arteries we used antisense oligodeoxynucleotide (Antisense), the new selective neuropeptide Y Y1 receptor antagonist, BIBP3226 {(R)-N2-(diphenylacetyl)-N-[(4-hydroxyphenyl) methyl]-D-arginine-amide} and the reverse transcriptase-polymerase chain reaction (RT-PCR). Neuropeptide Y significantly potentiated the noradrenaline-induced contraction in non-incubated vessels (pEC50 6.4 +/- 0.2 vs. 5.9 +/- 0.2) and in vessels incubated with 1 microM Sense oligodeoxynucleotide (Sense) (pEC50 6.0 +/- 0.1 vs. 5.6 +/- 0.2). In vessels incubated with 1 microM Antisense the potentiating effect of neuropeptide Y was completely abolished. BIBP3226 (1 microM) inhibited the neuropeptide Y-induced potentiation in human omental arteries (pEC50 5.8 +/- 0.3 vs. 6.4 +/- 0.2). Finally, messenger RNA for the neuropeptide Y Y1 receptor was detected using RT-PCR. On the basis of our results we conclude that the neuropeptide Y-induced potentiation of the noradrenaline-induced contraction is mediated by the neuropeptide Y Y1 receptor.
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PMID:Neuropeptide Y potentiates noradrenaline-induced contraction through the neuropeptide Y Y1 receptor. 898 51

In a murine model of rickettsial disease in which, as in human rickettsioses, endothelial cells are the major target of infection, depletion of IFN-gamma or TNF-alpha converts a sublethal infection into a uniformly fatal disease with overwhelming rickettsial growth and decreased nitric oxide (NO) synthesis. The kinetics of NO production and rickettsial survival and growth were examined on Days 1, 2, and 3 after inoculation of endothelial cells with Rickettsia conorii under four different experimental conditions: (a) no cytokine treatment, (b) treatment with IFN-gamma and TNF-alpha, (c) treatment with cytokines and NG monomethyl-L-arginine, a competitive inhibitor of NO synthesis, and (d) treatment with sodium nitroprusside, a source of NO. Endothelial cells were examined for the presence of inducible nitric oxide synthase mRNA by specific reverse transcriptase-PCR after stimulation with IFN-gamma and TNF-alpha. Cytokine-stimulated and unstimulated rickettsiae-infected endothelial cells were examined by electron microscopy to observe the cellular and rickettsial events. Transformed and diploid mouse endothelial cells stimulated by the combination of recombinant murine IFN-gamma and TNF-alpha killed intracellular Rickettsia conorii by a mechanism that required the synthesis of NO. The antirickettsial effect and NO synthesis were inhibited by treatment of endothelial cells with NG monomethyl-L-arginine. Addition of nitroprusside, which released NO, also exerted a strong antirickettsial effect in the absence of IFN-gamma and TNF-alpha. Endothelial inducible nitric oxide synthase mRNA was detected 4 hours after cytokine stimulation, increased substantially at 8 hours, and decreased to low levels by 72 hours. Ultrastructural evaluation revealed that endothelial cells effected rickettsial killing in association with autophagy. Double membranes of endothelial cell granular endoplasmic reticulum surrounded rickettsiae, which were also observed being destroyed within phagolysosomes. This study demonstrated for the first time that endothelial cells are capable of killing rickettsiae. When stimulated by the combination of IFN-gamma and TNF-alpha, mouse endothelial cells kill Rickettsia conorii by an NO-dependent mechanism. Within the endothelium, NO exerts a rickettsicidal effect.
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PMID:Cytokine-induced, nitric oxide-dependent, intracellular antirickettsial activity of mouse endothelial cells. 901 Apr 56

We have previously proposed that pro-inflammatory cytokines and nitric oxide (NO) contributed to reversible myocardial depression in patients with sepsis and congestive heart failure. Sepsis and heart failure are also associated with refractoriness to beta-adrenoceptor agonists. Therefore, the chronotropic effects of cytokines and the NO synthase inhibitor, NG-methyl-L-arginine (NMA), on beta-adrenoceptor stimulation of neonatal cardiac myocytes were studied. Tumor necrosis factor alpha, interleukin-1 beta and interleukin-6 but not interleukin-4 or interleukin-5 significantly enhanced spontaneous beating rates compared to untreated myocytes in serum-free media for 48 h (P < 0.01; n = 12 for each). NMA also significantly enhanced spontaneous beating rates (P < 0.01; n = 12 for each). Only interleukin-1 beta treatment resulted in significant nitrite production, immunohistochemical staining for inducible nitric oxide synthase and detection of inducible NO synthase messenger RNA by reverse transcriptase-polymerase chain reaction (RT-PCR). However, tumor necrosis factor alpha, interleukin-1 beta, interleukin-6, and NMA each completely blocked the positive chronotropic effects of the beta-adrenoceptor agonist, isoproterenol (P < 0.01; n = 12 for each). These findings are most consistent with an inducible NO synthase-independent effect of cytokines and NMA on the chronotropic responses of neonatal cardiac myocytes to beta-adrenoceptor stimulation. This effect of cytokines and NMA on adrenergic signaling may involve a myocardial constitutive NO synthase or an NO-independent mechanism.
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PMID:Cytokines and nitric oxide synthase inhibitor as mediators of adrenergic refractoriness in cardiac myocytes. 905 50

Although nitric oxide (NO) is a well documented effector molecule in rodent macrophages, its significance in human mononuclear phagocytic cells has been controversial. The foreign body inflammatory reaction around loosened joint replacement implants leads to formation of an osteolytic granulomatous pseudo-synovial membrane rich in activated macrophages. We studied 13 specimens of interface membrane tissue collected from revision surgery of aseptically loosened hip and knee prostheses for the presence of inducible NO synthase (iNOS). The presence of iNOS was demonstrated immunohistochemically in 10 of these specimens. Within the tissue this enzyme was confined to macrophages and vascular endothelial cells. iNOS activity was demonstrated biochemically by measuring the calcium-independent generation of citrulline from L-arginine, and the presence of iNOS mRNA was demonstrated using reverse transcriptase polymerase chain reaction. NO synthesis in the interface tissue may be an important factor in the maintenance of the inflammatory and osteolytic processes.
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PMID:Nitric oxide synthase is expressed in human macrophages during foreign body inflammation. 906 Aug 26

We have previously reported an interaction of nitric oxide (NO) and cyclic 3',5'-guanosine monophosphate (cGMP) in erythropoietin (Epo) production. Further studies have been carried out to clarify the role of NO in the hypoxic regulation of Epo production in Epo producing human hepatocellular carcinoma (Hep3B) cells, which produce Epo in response to physiological stimuli. Our reverse transcriptase-polymerase chain reaction (RT-PCR) technique revealed the expression of iNOS mRNA in Hep3B cells after incubation under hypoxic (1% O2) conditions for 6 hr. Hypoxia also significantly increased medium levels of nitrite in Hep3B cells. In order to investigate the role of NO in Epo production in Hep3B cells under normoxic (20% O2) conditions, we have studied the effects of interferon-gamma (IFN-gamma) on Epo production. IFN-gamma is known to induce iNOS and enhance the production of NO. IFN-gamma produced significant increases in medium levels of Epo and nitrite. IFN-gamma also significantly increased cGMP levels in Hep3B cells. Furthermore, NG-nitro-L-arginine methyl ester (L-NAME), an NO synthase inhibitor, significantly decreased IFN-gamma induced elevations in medium levels of Epo and nitrite as well as cGMP levels in Hep3B cells. These results provide further support for an important role of the NO/cGMP system in hypoxic regulation of Epo production in Hep3B cells.
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PMID:Inducible nitric oxide synthase expression and erythropoietin production in human hepatocellular carcinoma cells. 912 39

1. We have investigated the mechanism by which L-arginine stimulates membrane depolarization, an increase of intracellular calcium ([Ca2+]i) and insulin secretion in pancreatic beta-cells. 2. L-Arginine failed to affect beta-cell metabolism, as monitored by NAD(P)H autofluorescence. 3. L-Arginine produced a dose-dependent increase in [Ca2+]i, which was dependent on membrane depolarization and extracellular calcium. 4. The cationic amino acids L-ornithine, L-lysine, L-homoarginine (which is not metabolized) and NG-monomethyl-L-arginine (L-NMMA, a nitric oxide synthase inhibitor) produced [Ca2+]i responses similar to that produced by L-arginine. The neutral nitric oxide synthase inhibitors NG-nitro-L-arginine (L-NNA) and N omega-monomethyl-L-arginine (L-NAME) also increased [Ca2+]i. D-Arginine was ineffective. 5. L-Arginine did not affect whole-cell Ca2+ currents or ATP-sensitive K+ currents, but produced an inward current that was carried by the amino acid. 6. The reverse transcriptase-polymerase chain reaction demonstrated the presence of messenger RNA for the murine cationic amino acid transporters mCAT2A and mCAT2B within the beta-cell. 7. L-Arginine did not affect beta-cell exocytosis as assayed by changes in cell capacitance. 8. Our data suggest that L-arginine elevates [Ca2+]i and stimulates insulin secretion as a consequence of its electrogenic transport into the beta-cell. This uptake is mediated by the mCAT2A transporter.
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PMID:Electrogenic arginine transport mediates stimulus-secretion coupling in mouse pancreatic beta-cells. 913 Jan 59

Foscarnet (trisodium phosphonoformate, PFA) is an effective inhibitor of retroviral reverse transcriptase (RT) and is known to block the replication of human immunodeficiency virus type 1 (HIV-1). In this article we analyzed the evolutionary process in generating HIV-1 strains related to drug resistance, using PFA as a selective pressure. PFA inhibited virus replication and protected the virus-induced cell killing, but it did not completely eliminate HIV-1 during the course of 7 weeks of treatment. The nucleotide sequence of the 859-bp DNA fragment spanning the core region of the HIV-1 pol gene was determined for 51 clones obtained from genomic DNA of the HIV-1-infected cells at different time points during PFA treatment. The nucleotide sequence analysis documented the presence of a minor HIV-1 variant prior to the PFA treatment. Molecular evolutionary techniques were utilized to analyze how the minor HIV-1 clones became predominant during this evolutionary process under the selective pressure of PFA. A phylogenetic tree analysis divided these 51 HIV-1 clones into 3 groups. One of the groups consisted of the clones associated with the resistance to PFA. The clones belonging to this group became predominant over time during the course of PFA treatment. Thus, the acquisition of PFA resistance by HIV-1 was considered to be due to clonal selection. Furthermore, among the various amino acid substitutions observed, the substitution of arginine at position 172 by lysine (Arg172Lys) clearly distinguished this group from the others. Since the consistent amino acid substitution observed here has not been identified in the HIV-1 strains resistant to other RT inhibitors, PFA in combination with other RT inhibitors is considered to be a feasible candidate for a convergent combined chemotherapy against HIV-1 in the treatment of patients with AIDS and related conditions.
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PMID:Clonal selection of HIV type 1 variants associated with resistance to foscarnet in vitro: confirmation by molecular evolutionary analysis. 913 74

The carbocyclic nucleoside 1592U89 is a selective inhibitor of the human immunodeficiency virus (HIV), targeting the reverse transcriptase (RT). In vitro selection studies were undertaken to generate resistant variants with both HIV type 1 (HIV-1) wild-type strain HIV-1(HXB2) and 3'-azido-3'-deoxythymidine (AZT)-resistant strain HIV-1(RTMC). At least two or three mutations in RT were required to produce a 10-fold reduction in susceptibility. The first RT mutation selected was at codon 184, methionine (M) to valine (V), for HIV-1(HXB2) and HIV-1(RTMC), conferring two- and fivefold resistance, respectively. Two additional mutations were selected with HIV-1(HXB2), either leucine (L) 74 to V and lysine (K) 65 to arginine (R) (first-passage series) or L74 to V and tyrosine (Y) 115 to phenylalanine (F) (second-passage series). Cloned variants, obtained from the 1592U89 selection, were either double RT mutants 65R/184V and 74V/184V or triple RT mutant 74V/115Y/184V. Molecular clones were constructed with single, double, and triple combinations of these mutations for resistance analysis with different RT inhibitors. Each individual mutation conferred only low-level resistance (two- to fourfold) to 1592U89 in the HXB2 background. Double mutants containing the 184V mutation and triple mutants showed slightly greater levels of resistance to 1592U89 (7- to 11-fold). Some of the 1592U89-resistant variants were cross-resistant with 2',3'-dideoxycytidine, 2',3'-dideoxyinosine, and (-)-2'-deoxy-3'-thiacytidine, but none were resistant to 2',3'-didehydro-3'-deoxythymidine or AZT.
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PMID:Combination of mutations in human immunodeficiency virus type 1 reverse transcriptase required for resistance to the carbocyclic nucleoside 1592U89. 914 75

The lack of sequence information and clones of porcine pulmonary artery endothelial cell (PAEC) constitutive nitric oxide synthase (ecNOS) cDNA limits comparative analysis between porcine and human PAEC. Therefore, we cloned, characterized and expressed the ecNOS cDNA from porcine PAEC. Two oligonucleotide primers were designed based on the published human ecNOS cDNA sequence and used to clone porcine PAEC ecNOS using 5' and 3' rapid amplification of cDNA ends reverse transcriptase polymerase chain reaction technique. A full-length ecNOS cDNA was cloned and sequenced, representing a protein of 1205 amino acids with a molecular mass of 134 kDa. A mammalian expression vector (pcDNA3) containing this cDNA was transfected into COS-7 cells, and ecNOS activity was detected by monitoring the formation of [3H]-citrulline from [3H]-L-arginine. Expression of ecNOS activity was predominantly associated (> 90%) with the total membrane fraction of these transfected cells. The deduced amino acid sequence of porcine ecNOS cDNA, containing binding sites for NADPH, flavin adenine dinucleotide and bound flavin mononucleotide, shows 94% identity to human ecNOS. The molecular weight of porcine ecNOS mRNA was estimated to be 4.7 kb by Northern blot analysis, similar to human ecNOS mRNA. This suggests that porcine ecNOS is similar to human ecNOS in deduced amino acid sequence and structure.
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PMID:Molecular cloning, characterization and expression of a nitric oxide synthase from porcine pulmonary artery endothelial cells. 914 2

We have previously described the private or family platelet antigen, Gro(a), which was identified in a case of neonatal alloimmune thrombocytopenia. The Gro(a) antigen was found to be located on the GP IIIa (beta3) subunit of the GP IIb/IIIa complex, the most prominent fibrinogen receptor of platelets. Initial experiments to characterize the Gro(a) antigen at the molecular genetic level were unsuccessful. We therefore decided to use a different strategy to unravel the molecular basis of this antigen. Platelet GP IIIa mRNA of a Gro(a+) and a Gro(a-) donor was amplified with suitable primers in a reverse transcriptase-polymerase chain reaction (RT-PCR) and subjected to single-strand conformational polymorphism (SSCP) analysis. Three regions of the amplified GP IIIa cDNA derived from the Gro(a+) donor showed a different SSCP pattern when compared to that of the Gro(a-) donor. Direct nucleotide sequence analysis of these three segments revealed that two of them contained silent substitutions, A1163C, A1553G and G1565A. The first and the latter changes were described previously. In the third segment a G1996A mutation was found, predicting an arginine --> histidine substitution at position 633 of the mature glycoprotein. PCR-ASRA (allele-specific restriction enzyme analysis) performed on cDNA as well as on genomic DNA with the restriction enzyme MaeIII showed that the His633 form of GPIIIa is restricted to the Gro(a+) phenotype. The observed mutation is three amino acids upstream of the mutation underlying the HPA-8/Sr system (Arg636Cys), suggesting this region of GP IIIa to be susceptible for mutations. Moreover, the presence of a silent mutation and two low-frequency forms of the silent polymorphisms strongly suggests that the G1996A mutation did not occur in a direct ancestral allele.
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PMID:The Arg633His substitution responsible for the private platelet antigen Gro(a) unravelled by SSCP analysis and direct sequencing. 916 97


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