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)

Genomic DNA sequencing in the vicinity of the pstA-1 gene from Mycobacterium tuberculosis allowed us to clone, sequence and identify a gene encoding a 70-kDa protein. The size of the protein was confirmed by in vitro coupled transcription/translation. Its N-terminal domain shows extensive sequence similarity with the catalytic domain of eukaryotic serine/threonine protein kinases, and the protein was therefore called Mbk (mycobacterial protein kinase). The deduced amino acid sequence contains two transmembrane segments, which flank a highly repetitive region, suggesting a receptor-like anchoring. The mbk gene was overexpressed in Escherichia coli and the gene product (Mbk) was purified as a fusion protein with gluthatione S-transferase. Recombinant Mbk was found to be autophosphorylated on threonine residues and capable of phosphorylating myelin basic proteins from bovine brain and histones from calf thymus on serine residues, both in a manganese-dependent manner. The phosphorylation of myelin basic proteins by Mbk was inhibited by calcium and by staurosporine, a widely used inhibitor of eukaryotic protein serine/threonine kinases. A similar gene was found in Mycobacterium bovis BCG DNA by Southern blot analysis. Its expression was detected in cultures of M. bovis BCG by reverse transcriptase/PCR. Although its biological role is unknown, it is the first serine/threonine protein kinase characterized in Mycobacteria.
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PMID:A serine/threonine protein kinase from Mycobacterium tuberculosis. 911 30

Trehalose dimycolate (TDM), a glycolipid present in the cell wall of Mycobacterium spp., is a powerful immunostimulant. TDM primes murine macrophages (Mphi) to produce nitric oxide (NO) and to develop antitumoral activity upon activation with low doses of lipopolysaccharide (LPS). In this study, we investigated the ability of TDM to induce interleukin 12 (IL-12) and the role of this cytokine in TDM-induced activation of murine Mphi. RNA isolated from peritoneal exudate cells (PEC) collected at different times after TDM injection was used to determine IL-12 (p35 and p40 subunits) and gamma interferon (IFN-gamma) mRNA levels by semiquantitative reverse transcriptase-PCR. Constitutive expression of IL-12p35 was observed in PEC from untreated as well as from TDM-injected mice. In contrast, expression of the IL-12p40 subunit was almost undetectable in control PEC but was dramatically upregulated in PEC from TDM-injected mice. IL-12p40 expression peaked at 8 h and subsided to baseline levels at 39 h postinjection. TDM was also able to induce IFN-gamma expression; however, kinetics of induction of IFN-gamma was different from that of IL-12p40. Maximal levels of IFN-gamma mRNA were reached by 24 h and did not return to baseline by 4 days. In addition, pretreatment of mice with neutralizing monoclonal antibodies directed against IL-12 (C15.6.7 and C15.1.2) blocked IFN-gamma mRNA induction in PEC from TDM-treated mice. We further determined if the induction of IL-12 and/or IFN-gamma contributes to the in vivo priming effect of TDM on peritoneal Mphi. TDM-injected mice were treated in vivo with anti-IL-12 or anti-IFN-gamma (XMG.1.6) monoclonal antibodies. TDM-primed Mphi were then activated in vitro with LPS and tested for their ability to produce NO and to develop cytostatic activity toward cocultivated L1210 tumor cells. Priming of Mphi by TDM was completely blocked by in vivo neutralization of either IL-12 or IFN-gamma as demonstrated by an absence of tumoricidal activity and NO production by TDM-elicited Mphi in the presence of LPS. Taken together our results show that TDM, a defined molecule from M. tuberculosis, induces in vivo production of IL-12. Moreover, synthesis of IL-12 mediates TDM priming of mouse peritoneal Mphi through IFN-gamma induction.
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PMID:Interleukin-12 synthesis is a required step in trehalose dimycolate-induced activation of mouse peritoneal macrophages. 911 75

Mycobacterium tuberculosis and human immunodeficiency virus type 1 (HIV-1) are virulent intracellular pathogens that invade and multiply within macrophages. The effect of M. tuberculosis on HIV-1 infection and replication was analyzed in vitro using human monocyte-derived macrophages (MDM) isolated from peripheral blood mononuclear cells by countercurrent centrifugal elutriation. Preinfection of MDM with M. tuberculosis followed by HIV-1 infection resulted in an increase in p24 release, reverse transcriptase activity, and infective virus production. In contrast, no increase in HIV-1 production was observed when MDM were infected with Mycobacterium avium complex or heat-killed M. tuberculosis. Coinfected MDM were potent stimulators of T cell proliferation, while HIV-1-infected MDM failed to present exogenous tuberculin to T cells. Furthermore, coinfected MDM showed an increased capacity to transmit HIV-1 to activated T cells. These results suggest that M. tuberculosis infection can both up-regulate HIV-1 infection and replication within MDM and increase the efficiency of virus transmission from infected MDM to T cells.
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PMID:Infection of human monocytes with Mycobacterium tuberculosis enhances human immunodeficiency virus type 1 replication and transmission to T cells. 918 Feb 1

Administration of low-dose recombinant human interleukin 2 (rhuIL-2) in combination with multidrug chemotherapy to patients with multidrug-resistant tuberculosis (MDR TB) induces measurable changes in in vitro immune response parameters which are associated with changes in the clinical and bacteriologic status of the patients. To determine the molecular basis of these changes, we have used semiquantitative reverse transcriptase-initiated PCR (RT-PCR) and differential display technology. During rhuIL-2 treatment of MDR TB patients, decreased levels of gamma interferon (IFN-gamma) mRNA in peripheral blood mononuclear cells (PBMC) relative to baseline levels were observed. However, at the site of a delayed-type hypersensitivity (DTH) response to purified protein derivative of tuberculin (PPD), the expression of cellular IFN-gamma and IL-2 mRNAs was increased during rhuIL-2 therapy. Levels of other cytokine mRNAs were not significantly affected by rhuIL-2 administration. Using differential-display RT-PCR, we identified several genes expressed at the DTH skin test site which were up- or down-regulated during rhuIL-2 treatment. Cytochrome oxidase type I mRNA was increased in response to rhuIL-2 therapy relative to baseline levels, as was heterogeneous nuclear ribonuclear protein G mRNA. CD63, clathrin heavy chain, and beta-adaptin mRNAs, all of which encode proteins associated with the endocytic vacuolar pathway of cells, were also differentially regulated by rhuIL-2 administration. The differential effects of IL-2 were confirmed in vitro by using PBMC obtained from PPD-positive individuals stimulated with Mycobacterium tuberculosis and IL-2. The differential expression of genes may provide a surrogate marker for leukocyte activation at a mycobacterial antigen-specific response site and for the development of an enhanced antimicrobial response which may result in improved outcomes in MDR TB patients.
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PMID:Differential gene expression in response to adjunctive recombinant human interleukin-2 immunotherapy in multidrug-resistant tuberculosis patients. 959 98

Laboratory techniques for the diagnosis of central nervous system (CNS) infections are rapidly improving but at present have limitations that necessitate our guarded enthusiasm. Enteroviruses are the most common infectious agents of viral meningitis for which an etiology can be determined, and it is anticipated that the use of the reverse transcriptase polymerase chain reaction (RT-PCR) technique should significantly improve the identification of the etiologic agent of aseptic meningitis. The combination of the polymerase chain reaction technique with laboratory methods for the determination of intrathecal antibody production to herpes simplex virus and varicella-zoster virus have improved the rapidity with which these viral infections can be diagnosed. The pearls and pitfalls of the use of these laboratory techniques in the diagnosis of viral meningitis, recurrent meningitis, and focal encephalitis are included. Recommendations for the empiric therapy of bacterial meningitis in children and adults have changed because of the emergence of penicillin and cephalosporin-resistant pneumococcal organisms. The currently recommended antibiotics and their dosages are included. The evidence for the efficacy of dexamethasone therapy in bacterial meningitis is provided. Meningitis due to Mycobacterium tuberculosis is increasingly recognized, and the initiation of empiric antituberculous chemotherapy should not await the results of CSF cultures. Toxoplasma encephalitis and primary CNS lymphoma are the most common cause of mass lesions in patients with HIV, and the diagnostic techniques to distinguish between these two infections is reviewed. A short discussion of the best test for the diagnosis of neurosyphilis is provided.
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PMID:Pearls and pitfalls in the diagnosis and management of central nervous system infectious diseases. 960 16

The possibility that mRNA from Mycobacterium tuberculosis and M. bovis BCG may present polyadenylation at the 3' end was investigated. The total RNA, extracted from the bacterial cells and treated with DNase, was used as substrate for reverse transcriptase (RT)-dependent cDNA synthesis. The RT reaction was primed with oligo(dT) and with downstream specific primers for the genes of the antigens 65 KDa and 85-C. PCR probing of the reaction products for cDNAs of the two mycobacterial genes yielded the expected 225 and 307 bp bands when RT synthesis was primed by oligo(dT) and by downstream specific primers. Reaction products from oligo(dT)-primed RT of RNase-treated RNA and untranscribed RNA, probed by PCR, failed to generate the 225 and 307 bp specific bands. These findings support the existence of polyadenylated tracts in mRNA of mycobacteria that can be targeted by oligo(dT) primers to initiate RT-dependent cDNA synthesis. This may result in an advance in the study of gene expression in these and possibly other bacteria.
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PMID:Oligo(dT)-primed synthesis of cDNA by reverse transcriptase in mycobacteria. 967 15

Recent advances in the chemotherapeutic agents against HIV enabled us to conduct combination therapies using two nucleoside reverse transcriptase inhibitors and a protease inhibitor. The three-drug combination chemotherapies have been shown to be very potent in inhibiting HIV replication; they markedly suppress plasma HIV-RNA levels, elevate CD4 counts, reduce opportunistic infections and prolong survival of the patients. Early and hard treatment is now recommended. Among opportunistic infections in patients with HIV infection/AIDS, most frequent are respiratory tract infections including Pneumocystis carinii pneumonia, bacterial pneumonia, pulmonary tuberculosis, CMV pneumonia and fungus infections. Sensitivity and specificity of PCR method to detect Pneumocystis carinii are much better than the conventional Grocott stain of sputa. Early diagnosis of tuberculosis and atypical mycobacteriosis became possible using PCR and other molecular technology. Multi-drug resistant tuberculosis is fortunately rare among Japanese HIV-positive patients. Early and correct diagnosis of opportunistic infections markedly improves the prognosis of the patients.
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PMID:[HIV Infection/AIDS and respiratory tract infections in Japan]. 979 9

Regulation of interleukin (IL)-12 production by coexpression of tumor necrosis factor (TNF)-alpha, IL-10, and transforming growth factor (TGF)-beta in human monocytes infected with Mycobacterium tuberculosis H37Ra was analyzed. Also, since IL-12 induces interferon (IFN)-gamma, the effect of IFN-gamma on IL-12 expression was examined. IL-12 mRNA was measured by reverse transcriptase-polymerase chain reaction and IL-12 protein by ELISA. IL-12 p35 mRNA was constitutive and inducible. IL-12 p70 protein paralleled IL-12 p40 protein expression. TNF-alpha protein expression occurred earlier than IL-12 p40 protein but was not required for IL-12 induction. Addition or neutralization of TGF-beta did not significantly alter IL-12 induction. In contrast, recombinant IL-10 reduced IL-12 and neutralization of IL-10 minimally enhanced IL-12. A pronounced increase in IL-12 followed IFN-gamma pretreatment, which selectively up-regulated IL-12 p35 mRNA. Further understanding of operative cytokine networks during M. tuberculosis infection may improve strategies for vaccine development and immunotherapy.
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PMID:Regulation of interleukin-12 by interleukin-10, transforming growth factor-beta, tumor necrosis factor-alpha, and interferon-gamma in human monocytes infected with Mycobacterium tuberculosis H37Ra. 980 41

These guidelines update previous CDC recommendations for the diagnosis, treatment, and prevention of tuberculosis (TB) among adults and children coinfected with human immunodeficiency virus (HIV) in the United States. The most notable changes in these guidelines reflect both the findings of clinical trials that evaluated new drug regimens for treating and preventing TB among HIV-infected persons and recent advances in the use of antiretroviral therapy. In September 1997, when CDC convened a meeting of expert consultants to discuss current information about HIV-related TB, special emphasis was given to issues related to coadministration of TB therapy and antiretroviral therapy and how to translate this information into management guidelines. Thus, these guidelines are based on the following scientific principles: * Early diagnosis and effective treatment of TB among HIV-infected patients are critical for curing TB, minimizing the negative effects of TB on the course of HIV, and interrupting the transmission of Mycobacterium tuberculosis to other persons in the community. * All HIV-infected persons at risk for infection with M. tubercu losis must be carefully evaluated and, if indicated, administered therapy to prevent the progression of latent infection to active TB disease and avoid the complications associated with HIV-related TB. * All HIV-infected patients undergoing treatment for TB should be evaluated for antiretroviral therapy, because most patients with HIV-related TB are candidates for concurrent administration of antituberculosis and antiretroviral drug therapies. However, the use of rifampin with protease inhibitors or nonnucleoside reverse transcriptase inhibitors is contraindicated. Ideally, the management of TB among HIV-infected patients taking antiretroviral drugs requires a) directly observed therapy, b) availability of experienced and coordinated TB/HIV care givers, and in most situations, c) use of a TB treatment regimen that includes rifabutin instead of rifampin. Because alternatives to the use of rifampin for antituberculosis treatment are now available, the previously recommended practice of stopping protease inhibitor therapy to allow the use of rifampin for TB treatment is no longer recommended for patients with HIV-related TB. The use of rifabutin-containing antituberculosis regimens should always include an assessment of the patient's response to treatment to decide the appropriate duration of therapy (i.e., 6 months or 9 months). Physicians and patients also should be aware that paradoxical reactions might occur during the course of TB treatment when antiretroviral therapy restores immune function. Adding to CDC's current recommendations for administering isoniazid preventive therapy to HIV-infected persons with positive tuberculin skin tests and to HIV-infected persons who were exposed to patients with infectious TB, this report also describes in detail the use of new shortcourse (i.e., 2 months) multidrug regimens (e.g., a rifamycin, such as rifampin or rifabutin, combined with pyrazinamide) to prevent TB in persons with HIV infection. A continuing education component for U.S. physicians and nurses is included.
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PMID:Prevention and treatment of tuberculosis among patients infected with human immunodeficiency virus: principles of therapy and revised recommendations. Centers for Disease Control and Prevention. 980 43

Multidrug-resistant tuberculosis patients respond poorly to antituberculosis therapy and therefore require new modalities of treatment to overcome the infection. Administration of low dose recombinant human interleukin 2 (rhuIL-2) in combination with chemotherapy to multidrug-resistant tuberculosis patients resulted in reduced or cleared sputum acid-fast bacilli in about 60% of the patients in association with enhanced activation of the immune system. Daily rhuIL-2 administration for 30 days induced increases in CD25+ and CD56+ cells in the blood. rhuIL-2 therapy also resulted in increased expression of gamma-interferon and IL-2 mRNA at the site of a delayed-type hypersensitivity (DTH) response to purified protein derivative of tuberculin. Differential display reverse transcriptase PCR revealed several genes expressed at the DTH skin test site that were up- or down-regulated during rhuIL-2 treatment. The differentially regulated genes included components of endocytic vacuoles, enzymes of the respiratory pathway and other regulators of cellular function. The physiological importance of the differential expression of these genes is under investigation to determine their roles in leukocyte activation and in the development of an antimycobacterial response.
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PMID:Recombinant interleukin 2 adjunctive therapy in multidrug-resistant tuberculosis. 994 3


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