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)

Cardiac hypertrophy and heart failure are frequently accompanied by elevated plasma levels of tumor necrosis factor alpha (TNF alpha), the pathogenetic relevance of this finding being a matter of debate. In human acute septic cardiomyopathy, on the other hand, the negative inotropic impact of TNF alpha on the heart is well documented and frequently ascribed to the induction of inducible nitric oxide (NO) synthase (iNOS) and an enhanced production of NO in the heart. Yet the present study presents evidence that in cardiomyocytes TNF alpha in non-toxic concentrations specifically depresses contractile performance independent of NO. In spontaneously beating neonatal rat cardiomyocytes, TNF alpha in a low, pathophysiologically relevant concentration (10 U/ml, 1-3 days) does not alter basal pulsation amplitude, but blocks alpha- and beta-adrenoceptor-stimulated increase in contractility and beating irregularity and impairs the impact of high extracellular calcium on contractile performance. However, this low TNF alpha-concentration does not suffice to induce iNOS - documented by reverse transcriptase polymerase chain reaction - or enhance nitrite concentrations in the cell culture supernatants as a measure of cellular NO production, neither in the presence nor absence of dexamethasone (0.1 micro M). Only in high concentration - the specific proinflammatory action being documented by an enhanced release of interleukin-6 from cardiomyocytes - TNF alpha (1000 U/mol; 6, 24 h) weakly induces the mRNA for iNOS, with a consecutive moderate rise in cellular nitrite production. TNF alpha-incubation (10-1000 U/ml) does not alter the morphological appearance of the cells displayed by phase contrast microscopy or evoke gross cytotoxicity.
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PMID:Tumor necrosis factor alpha (TNF alpha) is cardiodepressant in pathophysiologically relevant concentrations without inducing inducible nitric oxide-(NO)-synthase (iNOS) or triggering serious cytotoxicity. 940 66

To systematically elucidate the gene expression of inflammatory and immune modulators following middle cerebral artery occlusion (MCAO) in the rat, we studied interleukin-10 (IL-10) along with tumor necrosis factor alpha (TNF-alpha), interleukin-1 beta (IL-1beta) and interleukin-2 (IL-2). Gene expression of these cytokines was studied ipsilateral and contralateral to the MCAO, with mRNA expression levels evaluated 2, 4, 6, 8 and 12 h following permanent MCAO by reverse transcriptase polymerase chain reaction (RT-PCR). In the ischemic hemisphere TNF-alpha and IL-1beta mRNA increased at 2 h following MCAO and peaked at 6 h, with IL-10 mRNA detected only at 6 h. Contralaterally, both TNF-alpha and IL-1beta mRNAs were expressed with a similar pattern to that in the ischemic hemisphere, but at lower levels, with no contralateral IL-10 expression. There was no difference in IL-2 gene expression between control and experimental animals in either hemisphere. These results demonstrate that IL-10 and TNF-alpha, IL-1beta gene expression is induced early following MCAO. The temporal profile of these cytokines is similar to that seen in sepsis, where TNF-alpha induces IL-10; subsequently IL-10 inhibits TNF-alpha expression. The similarity of the temporal profile of cytokine expression in sepsis and cerebral ischemia suggests that IL-10 should be studied as a potential inhibitor of TNF-alpha production in ischemic brain tissue. The factors inducing contralateral expression of the inflammatory cytokines, TNF-alpha and IL-1beta, along with the potential clinical significance of this remote cytokine gene expression, merit further study.
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PMID:Gene expression of IL-10 in relationship to TNF-alpha, IL-1beta and IL-2 in the rat brain following middle cerebral artery occlusion. 941 30

Adult periodontitis is a chronic destructive disease characterized by an interaction between gram-negative bacteria and the host inflammatory response. Microbial substances such as lipopolysaccharide can activate host cells, e.g., macrophages, fibroblasts and keratinocytes, to secrete proinflammatory cytokines including tumor necrosis factor alpha and interleukin 1 beta (IL-1 beta). This study examined the hypothesis that periodontitis tissue contains increased levels of cytokines that promote osseous and connective tissue destruction. To test this hypothesis, diseased and healthy gingival biopsies were examined for differences in the expression of cytokine mRNA for the pro-inflammatory cytokines tumor necrosis factor alpha and IL-1 beta and the anti-inflammatory cytokine IL-1ra using quantitative reverse transcriptase polymerase chain reaction and in situ hybridization methods. The levels of tumor necrosis factor alpha and IL-1ra mRNA were shown to be significantly higher in diseased than healthy tissues. Additionally, a significantly correlated expression of IL-1 beta and IL-1ra mRNA was seen in all tissue examined. Analysis of tissue sections by immunohistochemical and in situ hybridization techniques revealed a mononuclear cell infiltrate that consisted of a higher average number of cells staining positive for tumor necrosis factor alpha mRNA, CD14, and CD3 in the diseased than healthy tissues. Although both diseased and healthy tissues expressed IL-1 beta and IL-1ra mRNA in the epithelium, the diseased tissue biopsies expressed more IL-1 beta and IL-1ra mRNA in the connective tissue. These results implicate the potential involvement of both the pro- and anti-inflammatory cytokines in the regulation of the chronic inflammatory disease adult periodontitis.
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PMID:Quantitative assessment of inflammatory cytokine gene expression in chronic adult periodontitis. 957 7

The hepatic stellate cell (HSC), following a fibrogenic stimulus, is transformed from a quiescent to an activated cell. Cytokines induce NFkappaB activity in activated but not in quiescent HSCs with subsequent expression of NFkappaB-responsive genes, such as intercellular adhesion molecule (ICAM)-1 and interleukin (IL)-6. We investigated the effect of proteasome inhibitors and an IkappaB super-repressor on the cytokine mediated activation of NFkappaB, ICAM-1, and IL-6 in activated HSCs. Culture-activated HSCs were stimulated with IL-1beta or tumor necrosis factor alpha (TNFalpha) in the presence or absence of proteasome inhibitors, ALLN or MG-132, or after infection with an adenovirus expressing the IkappaB super-repressor (Ad5IkappaB) or beta-galactosidase (Ad5LacZ) as a control. NFkappaB activity was evaluated by immunofluorescence and by electrophoretic mobility shift assay. The steady state level of cytoplasmic IkappaB protein was measured by Western Blot. ICAM-1 and IL-6 expression was measured by reverse transcriptase-polymerase chain reaction and enzyme-linked immunosorbant assay. Proteasome inhibitors, which block the degradation of IkappaB, and the Ad5IkappaB, which provides an exogenous nondegradable IkappaB, block the stimulation of NFkappaB activity by TNFalpha and IL-1beta in activated HSCs. These reagents block the subsequent nuclear translocation of p65 NFkappaB and induction of ICAM-1 and IL-6 by cytokines. The specificities of the proteasome inhibitors and the IkappaB super-repressor are demonstrated by their failure to block c-Jun N-terminal kinase induction by cytokines. Cytokine-induced stimulation of NFkappaB, ICAM-1, and IL-6 is blocked by proteasome inhibitors and Ad5IkappaB in activated HSCs. Inhibition of IkappaBalpha degradation is a potential target for anti-inflammatory therapy in the liver and might influence the activation process of HSCs following fibrotic stimuli.
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PMID:Inhibition of NFkappaB in activated rat hepatic stellate cells by proteasome inhibitors and an IkappaB super-repressor. 958 6

The major target organ of systemic infection with the intracellular bacterium Listeria monocytogenes is the liver, to where inflammatory leukocytes are rapidly recruited. We determined by reverse transcriptase polymerase chain reaction the early chemokine response in the liver after systemic infection of mice with listeriae, and in parallel compared chemokine release from macrophages and hepatocytic cells in vitro. Murine bone marrow-derived macrophages (BMM) grown in fetal calf serum-supplemented medium were used as macrophages and the TIB75 cell line as hepatocytic cells. Within 1-3 hours, gene expression of monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1 alpha, MIP-2, KC, and interferon-gamma inducible protein-10 (IP-10) was upregulated in liver tissue of infected mice. BMM infected in vitro with L. monocytogenes showed a generalized chemokine response, and readily released MCP-1, MIP-1 alpha, MIP-2, and KC, as measured by enzyme-linked immunosorbent assay. In contrast, the chemokine response of hepatocytic cells was more restricted, and infection induced MCP-1 and KC, but not MIP-2 and MIP-1 alpha. Interferon gamma enhanced chemokine release from hepatocytic cells, but unexpectedly had either no or a negative effect on chemokine secretion by BMM cultured in serum-supplemented medium. Listeriolysin (Hly)-negative avirulent listeriae as well as listeriae killed by heat or gentamycin initiated a similar chemokine response in BMM and hepatocytic cells as did wild-type L. monocytogenes. Stimulation of hepatocytic cells with the monokines, tumor necrosis factor alpha and interleukin (IL-)1 alpha, but not IL-6, augmented liberation of chemokines. Together, our data demonstrate an early hepatic chemokine response to L. monocytogenes in murine listeriosis. Probably, not only macrophages but also parenchymal cells participate in chemokine production.
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PMID:Macrophages and hepatocytic cells as chemokine producers in murine listeriosis. 971 70

In this study we demonstrate that peripheral blood mononuclear cells (PBMC) of patients with IgA nephropathy (IgAN) express mRNA for tumor necrosis factor alpha (TNF-alpha) at a significantly lower frequency after stimulation for 24 hours with pokeweed mitogen than do PBMC of a control population. These differences were not seen in patient samples stimulated for only 3 hours. To identify the cells responsible for TNF-alpha expression after overnight mitogen stimulation, we performed reverse transcriptase polymerase chain reaction analysis after preparative flow cytometry of PBMC labelled with fluorescent monoclonal antibodies. After stimulation for 24 hours, PBMC of all patients tested displayed no detectable TNF-alpha mRNA; in the control PBMC, TNF-alpha mRNA was present in CD4+ and CD8+ T cells, as well as in CD19+ B cells in some samples. These results suggest that diminished expression of TNF-alpha by T cells may play a role in the pathogenesis of IgAN.
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PMID:Late expression of tumor necrosis factor-alpha is markedly depressed in patients with IgA nephropathy. 973 85

8-Difluoromethoxy-1-ethyl-6-fluoro-1,4-dihydro-7-[4-(2-methoxyp hen yl)-1- piperazinyl]-4-oxoquinoline-3-carboxylic acid (K-12) has recently been identified as a potent and selective inhibitor of human immunodeficiency virus type 1 (HIV-1) transcription. In this study, we examined several combinations of K-12 and other antiretroviral agents for their inhibitory effects on HIV-1 replication in acutely and chronically infected cell cultures. Combinations of K-12 and a reverse transcriptase (RT) inhibitor, either zidovudine, lamivudine, or nevirapine, synergistically inhibited HIV-1 replication in acutely infected MT-4 cells. The combination of K-12 and the protease inhibitor nelfinavir (NFV) also synergistically inhibited HIV-1, whereas the synergism of this combination was weaker than that of the combinations with the RT inhibitors. K-12 did not enhance the cytotoxicities of RT and protease inhibitors. Synergism of the combinations was also observed in acutely infected peripheral blood mononuclear cells. The combination of K-12 and cepharanthine, a nuclear factor kappa B inhibitor, synergistically inhibited HIV-1 production in tumor necrosis factor alpha-stimulated U1 cells, a promonocytic cell line chronically infected with the virus. In contrast, additive inhibition was observed for the combination of K-12 and NFV. These results indicate that the combinations of K-12 and clinically available antiretroviral agents may have potential as chemotherapeutic modalities for the treatment of HIV-1 infection.
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PMID:Inhibition of human immunodeficiency virus type 1 replication by combination of transcription inhibitor K-12 and other antiretroviral agents in acutely and chronically infected cells. 1004 56

Many cell types are capable of expressing inducible nitric oxide synthase (iNOS) in response to cytokines or endotoxin. We detected iNOS mRNA by reverse transcriptase polymerase chain reaction in CD34+ human bone marrow cells after 48-hour incubation with interferon-gamma (IFN-gamma)/tumor necrosis factor alpha (TNF-alpha) and IFN-gamma/lipopolysaccharide. Based on this finding, we examined the effect of nitric oxide (NO) on hematopoiesis and particularly on proliferation and survival of CD34+ marrow cells in in vitro culture. When CD34+ cells were cultured in the presence of an NO donor, S-nitroso-N-acetyl-D,L-penicillamine (SNAP), a dose-dependent inhibition of cell proliferation was observed. Addition of the selective iNOS inhibitor, L-N6-(1-iminoethyl)-lysine hydrochloride (L-NIL) at a dose of 500 microM increased the cell counts by 23% (range 0-89%). The expansion of total CD34+ cell number was 4-fold with a hematopoietic cytokine cocktail compared to 5.2-fold with the addition of L-NIL to this combination. At days 7 and 14 of culture, SNAP induced apoptosis in CD34+ human bone marrow cells detected by an in situ terminal deoxynucleotidyl transferase assay. The apoptosis was partially inhibited with the addition of L-NIL. SNAP also inhibited cell cycling, as evidenced by a 56% decrease in the number of cells in S phase after 5 days of culture in the presence of SNAP. To investigate if NO production was dependent on oxygen tension, J774A mouse macrophage cells were induced with lipopolysaccharide/IFN-gamma, and nitrite production measured by the Griess reaction. Nitrite production was persistently less in 5% compared to 21% oxygen. CD34+ marrow cells from normal donors were also grown under variable oxygen tension, and the cell proliferation in 5% oxygen was significantly greater at both 7 and 14 days of culture. CFU-GM colony growth also was increased in the low oxygen setting. The concentration of various cytokines was measured in CD34+ progenitor culture supernatants, including interleukin (IL)-1 alpha, IL-1 beta and TNF-alpha. SNAP increased IL-1 alpha production by CD34+ cells as well as from light-density bone marrow cells, whereas the effect on IL-1 beta and TNF-alpha production was not significant. Manipulation of oxygen tension and the inhibition of production of reactive oxygen and nitrogen intermediates may have potential to optimize cell expansion and progenitor preservation in ex vivo culture systems.
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PMID:Effect of nitric oxide production and oxygen tension on progenitor preservation in ex vivo culture. 1008 6

In this study, we examined the role of Fas-signaling in the apoptotic pathway in myelodysplastic syndromes (MDS). Ficoll-separated mononuclear cells from 18 bone marrow aspirate specimens obtained from 17 MDS patients, 4 normal healthy donors, and 3 acute myeloid leukemia patients transformed from MDS (t-AML) were studied for mRNA expression of Fas-L, Fas, and the effectors of their signaling, Caspase 1 and Caspase 3, using reverse transcriptase polymerase chain reaction. Fas-L, Fas, and Caspase 1 were detectable in all of the samples in the three groups. Caspase 3 was detectable both in MDS and t-AML specimens but was negligible in normal cells. The apoptotic index (AI%) determined by in situ end labeling of fragmented DNA in 4-hour cultures of mononuclear cells was significantly higher in MDS cells compared to normal or t-AML cells (mean +/- SEM: 2.3% +/- 0.4% in MDS, n = 10 vs. 0.6% +/- 0.2%, n = 4, P = 0.014 in normal cells, and 0.2% +/- 0.2%, n = 3, P = 0.007 in t-AML cells). Treatment of MDS cells with anti-Fas-L antibody suppressed apoptosis (AI%: 2.1% +/- 0.6% in untreated vs. 1.37% +/- 0.5% in treated, n = 6, P = 0.02), indicating functional participation of Fas-signaling in MDS. Further, it was found that Fas-L, Fas, and Caspase 1 mRNA expression remained unchanged in 4 hours. Caspase 3 expression appeared in normal cells after 4 hours and was present at both 0 and 4 hours in MDS and t-AML cells. In contrast to persistent expression in normal and t-AML cells, cells from the 5 MDS patients studied consistently showed significantly lowered or undetectable expression of a negative regulator of Fas, called Fas-associated phosphatase-1 (Fap-1) after 4 hours. Thus, the high AI% in MDS corresponds to a rapid decline in Fap-1. Furthermore, in tumor necrosis factor alpha (TNF-alpha) treated HL60 promyelocytic cells, a definite periodicity in the expression of different mRNAs was observed with upregulation of TNF-alpha itself at 30 minutes, increased expression of Fas and the appearance of Fas-L after 2 hours, and a decrease in Fap-1 expression after 8 hours. These results suggest that TNF-alpha not only induces the effectors of Fas-signaling but also may downregulate the inhibitor. We conclude that a spontaneous and rapid down-regulation of Fap-1, possibly induced by TNF-alpha, a cytokine shown to be present in excess in MDS marrows, may underlie the increased apoptotic death of hematopoietic cells in these patients. Interference with Fap-1 turnover may provide a new therapeutic modality for MDS.
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PMID:Spontaneous down-regulation of Fas-associated phosphatase-1 may contribute to excessive apoptosis in myelodysplastic marrows. 1049 46

The expression of endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) in samples of normal gastric mucosa and gastric cancer were examined by reverse transcriptase-polymerase chain reaction (RT-PCR) and semi-quantitative Western blot. In normal gastric mucosa, eNOS protein was found in all samples examined (mean, 70.2 +/- 60.1), relative to a standard protein. In gastric cancer specimens, eNOS protein was also detected in all samples, but the quantity (86.5 +/- 76.6) was not different from that found in samples of normal mucosa. The quantity of eNOS in gastric cancer tissues was negatively correlated with serosal invasion. iNbS mRNA, detected in nine of 18 cases, was slightly related to massive lymph node metastasis (n1-3 vs. n4). Neither tumor necrosis factor alpha (TNF-alpha) mRNA nor interleukin-6 (IL-6) mRNA was related to the expression of iNOS mRNA. These results suggest that iNOS not eNOS plays a role in gastric cancer tumor extension, but iNOS mRNA appears not to be induced by either TNF-alpha or IL-6.
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PMID:Expression of nitric oxide synthase in gastric cancer. 1052 16


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