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

---

Query: EC:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Historically, infections caused by Mycobacterium tuberculosis have been treated simultaneously with isoniazid and rifampin. As a consequence of this combined therapy, strains resistant only to rifampin were rarely recovered. However, recently there has been an increasing number of reports describing HIV-positive patients infected with mono-rifampin-resistant M. tuberculosis strains. Organisms cultured from seven patients (including six with AIDS) with infections caused by mono-rifampin-resistant M. tuberculosis, and seen at one New York City hospital, were analyzed by molecular techniques to test the hypothesis that dissemination of a single clone had occurred. IS6110 DNA fingerprinting and automated DNA sequencing of a region of the RNA polymerase beta subunit structural gene (rpoB) containing mutations that confer rifampin resistance showed that all organisms independently acquired the mono-rifampin-resistant phenotype. Molecular analysis of mono-rifampin-resistant organisms cultured from 13 additional patients in New York City confirmed independent strain origin. The data rule out the possibility of person-to-person strain transmission among these patients, and they suggest that host factors such as poor compliance with antituberculosis medications or decreased absorption of rifampin have been a driving force in the origin of these strains.
...
PMID:Independent origin of mono-rifampin-resistant Mycobacterium tuberculosis in patients with AIDS. 888 22

Differentiation of hematopoietic progenitor cells into T lymphocytes generally occurs in the unique environment of the thymus, a feature that has hindered efforts to model this process in the laboratory. We now report that thymic stromal cultures from rhesus macaques can support T-cell differentiation of human or rhesus CD34+ progenitor cells. Culture of rhesus or human CD34+ bone marrow-derived cells depleted of CD34+ lymphocytes on rhesus thymic stromal monolayers yielded CD3+CD4+CD8+, CD3+CD4+CD8-, and CD3+CD4-CD8+ cells after 10 to 14 days. In addition to classical T lymphocytes, a discrete population of CD3+CD8loCD16+CD56+ cells was detected after 14 days in cultures inoculated with rhesus CD34+ cells. CD3+ T cells arising from these cultures were not derived from contaminating T cells present in the CD34+ cells used to inoculate thymic stromal monolayers or from the thymic monolayers, as shown by labeling of cells with the lipophilic membrane dye PKH26. Expression of the recombinase activation gene RAG-2, which is selectively expressed in developing lymphocytes, was detectable in thymic cultures inoculated with CD34+ cells but not in CD34+ cells before thymic culture or in thymic stromal monolayers alone. Reverse transcriptase-polymerase chain reaction analysis of T cells derived from thymic stromal cultures of rhesus and human CD34+ cells showed a polyclonal T-cell receptor repertoire. T-cell progeny derived from rhesus CD34+ cells cultured on thymic stroma supported vigorous simian immunodeficiency virus replication in the absence of exogenous mitogenic stimuli. Rhesus thymic stromal cultures provide a convenient means to analyze T-cell differentiation in vitro and may be useful as a model of hematopoietic stem cell therapy for diseases of T cells, including acquired immunodeficiency syndrome.
...
PMID:In vitro T lymphopoiesis of human and rhesus CD34+ progenitor cells. 863 59

Kaposi's sarcoma (KS) accounts for more than 15% of AIDS-related malignancies. The etiology of KS is unresolved but is postulated to be multifactorial, involving viruses and overexpression of cellular growth factors and/or oncogenes. Recently, herpesvirus-like sequences (KSHV) were identified with high prevalence in AIDS-KS (AKS), endemic KS, and in classic KS biopsies (CKS). To confirm the presence and the prevalence of the KSHV sequences, 18 CKS and 13 AKS samples were tested using polymerase chain reaction (PCR) analysis. To our knowledge this is the highest number of CKS samples that has ever been included in a single study, and it is also important that the biopsies were obtained from different institutions and geographical locations. KSHV sequences were detected in 100% of the AKS samples and 72% of the CKS biopsies using PCR analysis. The presence of the unique KSHV sequences was confirmed by direct sequencing of representative PCR products obtained from AKS and CKS samples. Reverse transcriptase (RT)-PCR experiments showed that the KSHV sequences were transcribed to mRNA in both AKS and CKS samples. Our results confirm that the putative new herpesvirus-like agent is associated with both AKS and CKS and may have an etiological role in the pathogenesis of this malignancy.
...
PMID:Herpesvirus-like DNA sequences in classic Kaposi's sarcomas. 883 Jan 23

Mycobacterium avium complex (MAC) infection is the most common disseminated opportunistic infection encountered in patients with AIDS. We have studied the ability of specific Mycobacterium avium (MA) antigen to stimulate human monocyte-derived macrophages (MDM) to produce tumor necrosis factor-alpha (TNF-alpha). MDM stimulated with MA sonicate, MA 68 kDa and MA 48-52 kDa antigens were found to produce TNF-alpha in a dose-dependent manner. Reverse transcriptase-polymerase chain reaction analysis of mRNA extracts from antigen-stimulated MDM indicated that TNF-alpha mRNA expression was of brief duration and the time point of peak TNF-alpha mRNA levels was found to be antigen-specific. A significant difference in TNF-alpha production in response to MA 48-52 kDa antigen and M. bovis 65 kDa antigen was observed between MDM from normal and HIV positive individuals.
...
PMID:Macrophage release of tumor necrosis factor-alpha by Mycobacterium avium antigens. 887 Nov 13

We report the generation of recombinant vaccinia viruses (VVs) expressing the gag, pol, bel-1, and bet open reading frames of human foamy virus (HFV), and the establishment of a transient, VV-T7 RNA polymerase-directed expression system for the HFV env gene. The correct expression of the HFV proteins was demonstrated by radioimmunoprecipitation using monospecific rabbit antisera, by analysis of the subcellular distribution (for VVgag, VVpol, VVbel-1, and VVbet), and by the ability to induce syncytium formation (for the env expression system). The HFV pol gene was successfully expressed using its own ATG start codon. Foamy viruses are regarded as retroviruses with intracytoplasmatic capsid assembly. However, when VVgag and VVpol were used to study the HFV Gag-Pol protein interaction and particle formation, no HFV capsid structures were observed in singly or doubly infected cells. In addition, no cleavage of the Pr74gag precursor molecule by the pol-encoded protease was detected in doubly infected cells. Our results indicate that foamy virus particle assembly is fundamentally different from that of other retroviruses.
AIDS Res Hum Retroviruses 1997 Apr 10
PMID:Characterization of human foamy virus proteins expressed by recombinant vaccinia viruses. 910 Sep 94

Human immunodeficiency virus-infected patients occasionally exhibit alveolar septal wall thickening and decreases in gas diffusion capacity, but the mechanism underlying these abnormalities is unknown. The present study evaluated septal wall thickness and gas exchange properties in a murine model of the acquired immunodeficiency syndrome and determined whether there were alterations in lung lymphocyte deposition and activation that could contribute to changes in respiratory structure and function. Although alveolar septal wall thickness did not differ from control at 1, 2, and 4 wk postimmunosuppressive virus infection, at 8 wk after infection, septal wall thickness was substantially increased. Immunohistochemical evaluation at this time revealed marked increases in the septal wall deposition of fibronectin and collagen type IV. Pulmonary function tests on anesthetized mice with virus-induced septal wall thickening demonstrated that, although total lung capacity, compliance, and functional residual capacity were unaltered, diffusion capacity for carbon monoxide was significantly impaired. A diffuse nonspecific interstitial pneumonitis was present in lungs of immunodeficient mice, and flow cytometry indicated that both lymphocytes and macrophages were activated. Reverse transcriptase-polymerase chain reaction analysis of lung lymphocytes demonstrated enhanced mRNA expression for several cytokines known to affect lung structure. These results show that impaired gas exchange occurs in a murine model of acquired immunodeficiency syndrome and suggest that such alterations may be mediated by elaboration of cytokines from activated lung lymphocytes and macrophages.
...
PMID:Pulmonary mechanical and immunologic dysfunction in a murine model of AIDS. 914 44

Structures consistent in size, shape and character with various stages of a Lentivirus replicative cycle were observed by electron microscopy in 12-day peripheral-blood lymphocyte cultures from 10 of 17 Chronic Fatigue Syndrome patients and not in controls. Attempts to identify a lymphoid phenotype containing these structures by immunogold labelling failed and the results of reverse-transcriptase assay of culture supernatants were equivocal. The study was blind and case-controlled, patients being paired with age, sex and ethnically matched healthy volunteers. Prescreening of subjects included the common metabolic and immunological disorders, functional conditions and a virus-screen against hepatitis B and C, Epstein-Barr Virus, Cytomegalovirus and Human Immunodeficiency Virus.
...
PMID:Electron microscopic immunocytological profiles in chronic fatigue syndrome. 920 53

Failure to detect infection with HIV-1 non-B subtypes in some antibody screening assays has been shown. To date, however, no studies have been published evaluating the capacity of standard tests to quantify replication of divergent HIV-1 in cell culture. Reverse transcriptase (RT) activity and p24 antigen assays are the two methods most commonly used for this purpose. A homogeneous panel of HIV-1 subtype B viruses from northern Italy and a heterogeneous panel of diverse genetic subtypes (A to F and O) from different regions of the world were cultured under identical conditions. A new nonradioactive RT assay was used as a basis for comparison to evaluate the capacity of two p24 assays to quantify viral growth in both panels. Comparison of the p24 amount/RT activity (p24/RT) ratios showed that ratios in the subtype B panel tended to be markedly higher than in the diverse subtype panel. Greatest variation was seen with one of the subtype O isolates, where up to a 400 times lower ratio was obtained compared with the average ratio for the subtype B panel. In addition, one Thai subtype B virus also gave a markedly reduced ratio. Furthermore, comparison between the two p24 assays showed different abilities to detect p24 from different HIV-1 isolates. We discuss limitations for the use of anti-HIV-1 p24 antibodies produced by immunization with subtype B p24 in p24 assays.
AIDS Res Hum Retroviruses 1998 Mar 01
PMID:Differences in reverse transcriptase activity versus p24 antigen detection in cell culture, when comparing a homogeneous group of HIV type 1 subtype B viruses with a heterogeneous group of divergent strains. 951 96

Interferon (IFN) treatment of lentivirus-infected cells substantially reduces virus replication in vitro. Although the replication of both HIV-1 and simian immunodeficiency virus (SIV) is inhibited, IFN blocks the replication of these viruses at different stages of the viral life cycle. We previously demonstrated that in HIV-1-infected cells, IFN blocks a late step in viral replication, leading to a decrease in viral protein stability and a deregulation of polyprotein processing. In contrast, in SIV-infected cells, IFN blocks an early step in viral replication, between virus binding and reverse transcription. Thus, the viral gene products targeted by IFN may be different for each of these viruses. To attempt to define which viral proteins are targeted by the IFN response, we examined the effects of IFN on the replication of two SIV/HIV-1 (SHIV) chimeric viruses, SHIV-4(vpu+) and SHIV-4(vpu-) in 174 x CEM cells. These viruses were grown from constructs in which the SIVmac239 env, tat, and rev genes have been replaced with those HIV-1. The use of SHIV-4(vpu+) allowed us to examine whether vpu, which is unique to HIV-1, might contribute to the differential effects of IFN on HIV-1 and SIV replication. Surprisingly, we found that IFN inhibited SHIV replication differently than the replication of either HIV-1 or SIV. IFN treatment of SHIV-infected cells resulted in a decrease in the level of viral RNA expression but had no apparent effect on the integration of proviral DNA. Nuclear runoff transcription assays indicated that the reduction of SHIV RNA expression in IFN-treated cells was not due to alterations in RNA polymerase II-mediated transcription, suggesting that IFN may block SHIV replication by promoting the increased degradation of viral RNA. The presence of absence of the vpu gene did not alter the effects of IFN on SHIV replication, indicating that Vpu is not responsible for the differential effect of IFN on HIV-1 and SIV replication. Thus the response of SHIVs to antiviral agents such as IFN may be unique from either HIV-1 or SIV. This may be an important consideration when using SHIVs to evaluate anti-HIV-1 therapies in animal models of AIDS.
...
PMID:Interferon inhibits the replication of HIV-1, SIV, and SHIV chimeric viruses by distinct mechanisms. 970 19

(+)-Calanolide A, a novel dipyranocoumarin from the Malesian tree Calophyllum lanigerum var. austrocoriaceum, and a closely related compound, (-)-calanolide B, isolated from Calophyllum teysmannii var. inophylloide, are representatives of a distinct class of nonnucleoside HIV-1 specific reverse-transcriptase inhibitor under development as an AIDS chemotherapeutic. NCI repository specimens totalling 315 organic extracts from 31 taxa of Calophyllum were analyzed for related pyranocoumarins using a simple TLC system. A total of 127 extracts was initially classified as "positive"; eight out of the 31 taxa examined, representing perhaps 28 species already described (1/7-1/8 of all the species in this genus), contained prenylated coumarins, suggesting that these compounds, while sometimes abundantly present, are not widespread in the genus. Representative members of the TLC-positive extracts were partitioned between CH2C12 and 25% aqueous MeOH; the CH2C12-soluble materials were then analyzed by TLC and 1H NMR to confirm the presence of pyranocoumarins. The anti-HIV activity of the partitioned extracts are also presented. This study suggested that there are several distinctive coumarin chemotaxonomic markers distinguishing species of this genus.
...
PMID:Pyranocoumarins from tropical species of the genus Calophyllum: a chemotaxonomic study of extracts in the National Cancer Institute collection. 978 62


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---