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)

The antiviral nucleoside analogue 2',3'-dideoxycytidine (ddC) is a DNA chain terminator and/or inhibitor of human immunodeficiency virus (HIV) reverse transcriptase. We evaluated the effects of ddC in 36 New Zealand white rabbits. Three/sex were assigned to a control group and 5 treatment groups (10-250 mg/kg/day) for 13 or 18 weeks. Blood samples were taken 1 week prior to treatment and weekly thereafter to termination with the exception of the 2 highest dose groups, where blood sample collection was terminated at week 13. Selected hematological analytes were measured weekly with the exception of prothrombin time (PT) and activated partial thromboplastin time (APTT). PT and APTT and selected biochemical analytes were measured prior to treatment, at 7 weeks, and after 13 weeks of treatment. All rabbits were necropsied. Giemsa and hematoxylin and eosin sections were prepared from methacrylate-embedded marrow. Hematological effects included decreases in red blood cell count, hemoglobin, hematocrit, and white blood cell count and increases in mean corpuscular volume and red cell distribution width. Platelets, platelet volume, PT, APTT, and mean corpuscular hemoglobin concentration values were variable or unchanged. Effects were dose-related, most were seen at 1 week, and they persisted to term. Bone marrow histopathologic changes included megalocytosis, erythroid hypoplasia, bizarre erythroid nuclear morphology, nuclear-cytoplasmic asynchrony, and increased mitotic figures. Lymphopenia caused by ddC plateaued at 2 weeks and persisted until termination. Heteropenia (neutropenia) was sporadic. Biochemical values for serum analytes were unchanged by treatment. The principal hematological effect of ddC upon the erythron was characterized as a nonregenerative macrocytic anemia with erythroid hypoplasia and megaloblastic erythropoiesis.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Hematological effects of 2',3'-dideoxycytidine in rabbits. 133 36

Rhesus monkey cDNA for tissue factor pathway inhibitor (TFPI) was cloned by means of the reverse transcriptase-polymerase chain reaction, using liver mRNA, and its nucleotide sequence was determined by sequencing five independent clones. Monkey TFPI was found to have a signal peptide of 28 amino acid residues and to be a mature protein of 276 amino acid residues, in which three and seventeen amino acid residue substitutions compared to human TFPI were found, respectively. All the cysteine residues, three putative carbohydrate-linked asparagine residues, and the P1 amino acid residues of each of the three Kunitz inhibitor domains were conserved in the two species. Recombinant monkey TFPI (rTFPI) was isolated from the culture medium of transformed Chinese hamster ovary cells. Amino acid sequence analysis and immunoblotting analysis, using polyclonal and monoclonal antibodies, showed that the carboxyl-terminal basic part of Rhesus monkey rTFPI had been truncated. The inhibitory activity of monkey rTFPI was compared with that of human rTFPI without the carboxyl-terminal basic part. The prothrombin time of human plasma was slightly more prolonged by the addition of monkey rTFPI than by that of human rTFPI. However, no significant differences were found between the potencies of human and monkey rTFPI as to the inhibition of factor Xa and tissue factor-factor VIIa complex.
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PMID:Amino acid sequence and inhibitory activity of rhesus monkey tissue factor pathway inhibitor (TFPI): comparison with human TFPI. 808 87

Colominic acid is a homopolymer of N-acetylneuraminic acid (NANA), which has an alpha-2,8 ketosidic linkage between its polymer units. In this study, colominic acids were sulfated under different conditions and their antiviral activities against human immunodeficiency virus type 1 (HIV-1) were examined. Sulfated colominic acids, containing 6-12% sulfur, blocked the expression of HIV-1 antigen in MT-4 cells or C8166 cells following exposure to MOLT-4/HTLV-IIIB or HIV-1[GUN-1]. The compounds inhibited syncytium formation upon co-cultivation of MOLT-4 cells (clone 8) with MOLT-4/HTLV-IIIB cells and abolished the production of HIV-1 p24 antigen in culture medium of peripheral blood lymphocytes (PBLs). HIV-1 reverse transcriptase (RT) activity was not directly affected by the drugs. The compounds did not prolong activated partial thromboplastin time (APTT) at 10 and 1.0 microgram/ml, suggesting that they may not have appreciable side effects in vivo. These agents were still able to block the expression of HIV-1 antigen even when the cells were infected with HIV-1 in RPMI-1640 medium containing high percentages of fetal calf serum (FCS). These properties may be therapeutically advantageous if these compounds were considered for possible clinical use.
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PMID:Sulfated colominic acid: an antiviral agent that inhibits the human immunodeficiency virus type 1 in vitro. 879 13

Recombinant HIV-1 p66 (rp66, a subunit of reverse transcriptase (RT), a heterodimer of p66 and p51) was produced in Escherichia coli in three different ways. First, rp66 was produced as a part of the fusion protein of lacZ protein and HIV-1 pol protein consisting of three components: protease (p10), RT (p51/p66), and integrase (p31), and was released from the fusion protein by the protease (pol-rp66). Second, rp66 with Ser-Ser at the N-terminus was produced as a fusion protein with maltose-binding protein containing a factor Xa site between the two proteins (MBP-Ser-Ser-rp66) and was released from the fusion protein by factor Xa (Ser-Ser-rp66). Third, rp66 with Met-Gly at the N-terminus was produced in transformed cells (Met-Gly-rp66). The recombinant proteins were purified from sonic extracts of transformed cells by ammonium sulfate fractionation and various column chromatographies. MBP-Ser-Ser-rp66 and Met-Gly-rp66 were readily purified in sufficient amounts for labeling with 2, 4-dinitrophenyl groups and beta-D-galactosidase from E. coli, but pol-rp66 and Ser-Ser-rp66 were not for enzyme-labeling. Ser-Ser-rp66 was not only polymerized but also degraded to considerable extents. The purified preparations were labeled with 2,4-dinitrophenyl groups and beta-D-galactosidase and were tested in immune complex transfer enzyme immunoassay of antibody IgG to HIV-1 RT using serum samples from 600 HIV-1 seronegative and 30 HIV-1 seropositive subjects. Among various combined uses of the two labeled preparations, the uses of 2,4-dinitrophenylated MBP-Ser-Ser-rp66 and pol-rp66 with beta-D-galactosidase-labeled Met-Gly-rp66 showed the highest (99.8%) and the second highest (99.5%) specificities, which were higher than that with the labeled preparations used in the previous study (98. 0%).
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PMID:Preparations of recombinant HIV-1 p66 antigen to improve the specificity of immune complex transfer enzyme immunoassay of antibody IgG to HIV-1 reverse transcriptase. 1090 70

An ultrasensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) of antibody immunoglobulin G (IgG) to human immunodeficiency virus type 1 (HIV-1) has been developed using recombinant HIV-1 reverse transcriptase (rRT) as antigen. However, some disadvantages were noted in the use of rRT as antigen: rRT was produced only with low efficiency in widely used strains of Escherichia coli using a rather long DNA fragment (3,012 bp) of the whole HIV-1 pol gene, and it was impossible to produce fusion proteins of RT for simple purification, since rRT is a heterodimer of p66 and p51. In this study, recombinant HIV-1 p51 and p66 with Ser-Ser at the N termini (Ser-Ser-rp51 and Ser-Ser-rp66) were produced in E. coli as fusion proteins with maltose binding protein containing a factor Xa site between the two proteins and were purified after digestion with factor Xa. Ser-Ser-rp51 was produced in larger amounts and purified in higher yields with less polymerization than Ser-Ser-rp66. Polymerized Ser-Ser-rp66 tended to be precipitated on mercaptoacetylation for conjugation to beta-D-galactosidase (used as a label) and showed higher nonspecific and lower specific signals in an immune complex transfer enzyme immunoassay of antibody IgG to HIV-1 than Ser-Ser-rp51. The signals for serum samples of HIV-1-seropositive subjects by immune complex transfer enzyme immunoassay of antibody IgG to HIV-1 using Ser-Ser-rp51 as antigen (Y) were well correlated to those obtained using rRT as antigen (X) (log Y = 0.99 log X + 0.23; r = 0.99). Thus, the use of rp51 as antigen was advantageous over that of rp66 and rRT in an immune complex transfer enzyme immunoassay of antibody IgG to HIV-1.
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PMID:Recombinant p51 as antigen in an immune complex transfer enzyme immunoassay of immunoglobulin G antibody to human immunodeficiency virus type 1. 1106 8

Thrombin appears to underlie myometrial contractions in response to intrauterine bleeding. In a similar fashion, thrombin generated within the uterus in the absence of active bleeding could also produce contractions. These studies sought to determine whether functionally active prothrombin is expressed in the pregnant and nonpregnant rat uterus. Uteri were obtained from proestrus/estrus and timed-pregnant Sprague-Dawley rats. Western blots were performed using antithrombin antibodies. Immunohistochemical studies were performed using the same antibodies along with the Vector Elite ABC kit. Qualitative reverse transcriptase-polymerase chain reaction studies were performed using rat prothrombin-specific oligonucleotide primers. In vitro uterine contraction studies were performed using Taipan snake venom (an exogenous prothrombinase) and components of the plasma prothrombinase complex (Factors Xa and V) with and without pretreatment with thrombin inhibitors (heparin or hirudin). The Western blots demonstrated prothrombin peptides in myometrial tissue from estrus and pregnant rats. The immunohistochemical studies confirmed prothrombin peptides in both the circular and longitudinal myometrium, along with the endometrium. The reverse transcriptase-polymerase chain reaction studies demonstrated prothrombin mRNA in the endometrium and placenta, but not in the myometrial smooth muscle. The Taipan snake venom stimulated a significant increase in contractions, which were suppressed by pretreatment with heparin and hirudin. The Factor Xa and V complex also significantly stimulated uterine contractions, which were likewise inhibited by hirudin. These studies provide evidence supporting the expression of functionally active prothrombin in the pregnant and nonpregnant rat uterus. Based on the presence of its mRNA, prothrombin appears to be synthesized in the endometrium and placenta; in contrast, the myometrial smooth-muscle cells appear to sequester preformed prothrombin. These results support the hypothesis that intrauterine thrombin could play an autocrine/paracrine role in the regulation of contractile activity.
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PMID:Intrauterine expression of prothrombin in the sprague-dawley rat. 1238 11

Modern methods in genomics and high-throughput crystallography have ensured that we have access to a large and rapidly increasing, number of X-ray structures of protein-ligand complexes. A structure-based approach to drug design aims to exploit this information, but current methods are not suited to the examination of the large numbers of complexes available. We present computational tools that analyse and display multiple protein-ligand interactions and their properties in a simplified way. We illustrate how a novel binding-mode similarity metric is able to cluster 20 ligands complexed to HIV-1 reverse transcriptase into distinct groups. The properties of each cluster are then projected onto a group surface as a series of color gradients. Analysis of these surfaces reveals fundamental similarities and differences in the binding modes of these diverse compounds. In addition, the simplicity of the surface representations facilitates the transfer of information between the crystallographer, computational chemist and the chemist. We also show how two- and three-dimensional (2- and 3-D) similarities can be combined to provide enhanced understanding of 33 factor Xa inhibitor complexes. This methodology has enabled us to identify pharmaceutically relevant relationships between ligands and their binding modes that had previously been hidden in a wealth of data.
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PMID:Computational tools for the analysis and visualization of multiple protein-ligand complexes. 1616 59

Dietary dosing of the non-nucleoside reverse transcriptase inhibitor (NNRTI) TMC125, under development for treatment of HIV-1, resulted in a syndrome in male mice in a previous experiment that was termed hemorrhagic cardiomyopathy. In literature, this syndrome, which was described in rodent species only, was linked to vitamin K deficiency. Two mechanistic studies were conducted, one with dietary administration and a second with gavage. The syndrome was reproduced in only 1 male mouse after continuous dietary dosing, and TMC125 was demonstrated to affect coagulation parameters (prothrombin time [PT], activated partial thromboplastin time [APTT], clotting factors II, VII and XI), particularly in males. This was counteracted by vitamin K supplementation, supporting the hypothesis that the effects were mediated via a vitamin K deficiency. It is therefore concluded that the observed cardiac changes were not caused by a direct cardiotoxic effect but occurred after a state of disabled clotting ability with subsequent effects on mouse cardiac muscle. Therefore, clotting times can be used as adequate safety biomarkers in clinical trials. To date, no changes have been observed at therapeutic doses of TMC125, following human monitoring of PT and APTT. One other NNRTI, Efavirenz (Sustiva), has been reported to cause prolongation of coagulation times in rats and monkeys.
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PMID:Hemorrhagic cardiomyopathy in male mice treated with an NNRTI: the role of vitamin K. 1877 60

Crimean-Congo haemorrhagic fever (CCHF) is a potentially fatal viral disease. In this study, the aim was to investigate the prognostic factors affecting the patient's survival and risk factors to fatality. At Ondokuz Mayis University Faculty of Medicine, a tertiary referral centre near the CCHF epidemic region, patients with typical clinical findings and indicative microbiological results for IgM and/or reverse transcriptase-polymerase chain reaction of CCHF virus were enrolled in the study, from 2004 to 2007. Patients were divided into two subgroups according to their survival outcomes; group I (n = 44) survived patients and group II (n = 6) consisted of fatal cases. The median platelet count was significantly lower in the fatal group (11000/mm(3)) when compared to the survived group (49500/mm(3)). Aspartate transferase and alanine transferase (ALT) levels were significantly higher in group II, when compared to group I. Also, the median range of serum lactic dehydrogenase (LDH) and creatinine phosphokinase (CPK) levels were much more elevated, and prothrombin time (PT) and activated partial thromboplastin time (aPTT) were prolonged in fatal cases. There was also a significant difference in median age of these two groups. Advanced age, late admission, low platelet count, increased AST, ALT, CPK and LDH levels, and prolonged PT and aPTT could be an early indicator of poor prognosis in patients with CCHF.
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PMID:Risk factors for fatality in patients with Crimean-Congo haemorrhagic fever. 1953 53

Crimean-Congo hemorrhagic fever (CCHF) is a fatal viral disease that occurs in approximately 30 countries. It has the most extensive geographic range among the tick-borne viruses that affect human health. Recently, a 6-year-old boy presented with complaints of fever, fatigue, and loss of appetite. He revealed a history of tick bite in rural Istanbul three days prior to presentation. A hyperemia was detected at the site of the tick bite. Laboratory tests showed that alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, and creatine phosphokinase levels were elevated and that the prothrombin time and activated partial thromboplastin time were prolonged. Anti-CCHF virus IgM ELISA and a reverse transcriptase-PCR assay for CCHF RNA were both positive. Phylogenetic studies revealed that the virus was a new AP92-like CCHF strain, which was named KMAG-Hu-07-01 (accession number EU057975). This patient could provide important information on the transmission dynamics of CCHF infection.
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PMID:A newly identified Crimean-Congo hemorrhagic fever virus strain in Turkey. 2000 60


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