In Vitro Characterization of MK-1439, a Novel HIV-1 Nonnucleoside Reverse Transcriptase Inhibitor

PubMed Central

Feng, Meizhen; Falgueyret, Jean-Pierre; Tawa, Paul; Witmer, Marc; DiStefano, Daniel; Li, Yuan; Burch, Jason; Sachs, Nancy; Lu, Meiqing; Cauchon, Elizabeth; Campeau, Louis-Charles; Grobler, Jay; Yan, Youwei; Ducharme, Yves; Côté, Bernard; Asante-Appiah, Ernest; Hazuda, Daria J.; Miller, Michael D.

2014-01-01

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) are a mainstay of therapy for treating human immunodeficiency type 1 virus (HIV-1)-infected patients. MK-1439 is a novel NNRTI with a 50% inhibitory concentration (IC50) of 12, 9.7, and 9.7 nM against the wild type (WT) and K103N and Y181C reverse transcriptase (RT) mutants, respectively, in a biochemical assay. Selectivity and cytotoxicity studies confirmed that MK-1439 is a highly specific NNRTI with minimum off-target activities. In the presence of 50% normal human serum (NHS), MK-1439 showed excellent potency in suppressing the replication of WT virus, with a 95% effective concentration (EC95) of 20 nM, as well as K103N, Y181C, and K103N/Y181C mutant viruses with EC95 of 43, 27, and 55 nM, respectively. MK-1439 exhibited similar antiviral activities against 10 different HIV-1 subtype viruses (a total of 93 viruses). In addition, the susceptibility of a broader array of clinical NNRTI-associated mutant viruses (a total of 96 viruses) to MK-1439 and other benchmark NNRTIs was investigated. The results showed that the mutant profile of MK-1439 was superior overall to that of efavirenz (EFV) and comparable to that of etravirine (ETR) and rilpivirine (RPV). Furthermore, E138K, Y181C, and K101E mutant viruses that are associated with ETR and RPV were susceptible to MK-1439 with a fold change (FC) of <3. A two-drug in vitro combination study indicated that MK-1439 acts nonantagonistically in the antiviral activity with each of 18 FDA-licensed drugs for HIV infection. Taken together, these in vitro data suggest that MK-1439 possesses the desired properties for further development as a new antiviral agent. PMID:24379202

Design, synthesis and antiviral evaluation of novel heteroarylcarbothioamide derivatives as dual inhibitors of HIV-1 reverse transcriptase-associated RNase H and RDDP functions.

PubMed

Corona, Angela; Onnis, Valentina; Deplano, Alessandro; Bianco, Giulia; Demurtas, Monica; Distinto, Simona; Cheng, Yung-Chi; Alcaro, Stefano; Esposito, Francesca; Tramontano, Enzo

2017-08-31

In the continuous effort to identify new HIV-1 inhibitors endowed with innovative mechanisms, the dual inhibition of different viral functions would provide a significant advantage against drug-resistant variants. The HIV-1 reverse transcriptase (RT)-associated ribonuclease H (RNase H) is the only viral-encoded enzymatic activity that still lacks an efficient inhibitor. We synthesized a library of 3,5-diamino-N-aryl-1H-pyrazole-4-carbothioamide and 4-amino-5-benzoyl-N-phenyl-2-(substituted-amino)-1H-pyrrole-3-carbothioamide derivatives and tested them against RNase H activity. We identified the pyrazolecarbothioamide derivative A15, able to inhibit viral replication and both RNase H and RNA-dependent DNA polymerase (RDDP) RT-associated activities in the low micromolar range. Docking simulations hypothesized its binding to two RT pockets. Site-directed mutagenesis experiments showed that, with respect to wt RT, V108A substitution strongly reduced A15 IC50 values (12.6-fold for RNase H inhibition and 4.7-fold for RDDP), while substitution A502F caused a 9.0-fold increase in its IC50 value for RNase H, not affecting the RDDP inhibition, reinforcing the hypothesis of a dual-site inhibition. Moreover, A15 retained good inhibition potency against three non-nucleoside RT inhibitor (NNRTI)-resistant enzymes, confirming a mode of action unrelated to NNRTIs and suggesting its potential as a lead compound for development of new HIV-1 RT dual inhibitors active against drug-resistant viruses. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

(PCG) Protein Crystal Growth HIV Reverse Transcriptase

NASA Technical Reports Server (NTRS)

1992-01-01

HIV Reverse Transcriptase crystals grown during the USML-1 (STS-50) mission using Commercial Refrigerator/Incubator Module (CR/IM) at 4 degrees C and the Vapor Diffusion Apparatus (VDA). Reverse transcriptase is an enzyme responsible for copying the nucleic acid genome of the AIDS virus from RNA to DNA. Studies indicated that the space-grown crystals were larger and better ordered (beyond 4 angstroms) than were comparable Earth-grown crystals. Principal Investigators were Charles Bugg and Larry DeLucas.

A Laccase with Antiproliferative and HIV-I Reverse Transcriptase Inhibitory Activities from the Mycorrhizal Fungus Agaricus placomyces

PubMed Central

Sun, Jian; Chen, Qing-Jun; Cao, Qing-Qin; Wu, Ying-Ying; Xu, Li-Jing; Zhu, Meng-Juan; Ng, Tzi-Bun; Wang, He-Xiang; Zhang, Guo-Qing

2012-01-01

A novel 68 kDa laccase was purified from the mycorrhizal fungus Agaricus placomyces by utilizing a procedure that comprised three successive steps of ion exchange chromatography and gel filtration as the final step. The monomeric enzyme exhibited the N-terminal amino acid sequence of DVIGPQAQVTLANQD, which showed only a low extent of homology to sequences of other fungal laccases. The optimal temperature for A. placomyces laccase was 30°C, and optimal pH values for laccase activity towards the substrates 2,7′-azinobis[3-ethylbenzothiazolone-6-sulfonic acid] diammonium salt (ABTS) and hydroquinone were 5.2 and 6.8, respectively. The laccase displayed, at 30°C and pH 5.2, Km values of 0.392 mM towards hydroquinone and 0.775 mM towards ABTS. It potently suppressed proliferation of MCF 7 human breast cancer cells and Hep G2 hepatoma cells and inhibited human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) activity with an IC50 of 1.8 μM, 1.7 μM, and 1.25 μM, respectively, signifying that it is an antipathogenic protein. PMID:23093860

Design, discovery, modelling, synthesis, and biological evaluation of novel and small, low toxicity s-triazine derivatives as HIV-1 non-nucleoside reverse transcriptase inhibitors.

PubMed

Viira, Birgit; Selyutina, Anastasia; García-Sosa, Alfonso T; Karonen, Maarit; Sinkkonen, Jari; Merits, Andres; Maran, Uko

2016-06-01

A set of top-ranked compounds from a multi-objective in silico screen was experimentally tested for toxicity and the ability to inhibit the activity of HIV-1 reverse transcriptase (RT) in cell-free assay and in cell-based assay using HIV-1 based virus-like particles. Detailed analysis of a commercial sample that indicated specific inhibition of HIV-1 reverse transcription revealed that a minor component that was structurally similar to that of the main compound was responsible for the strongest inhibition. As a result, novel s-triazine derivatives were proposed, modelled, discovered, and synthesised, and their antiviral activity and cellular toxicity were tested. Compounds 18a and 18b were found to be efficient HIV-1 RT inhibitors, with an IC50 of 5.6±1.1μM and 0.16±0.05μM in a cell-based assay using infectious HIV-1, respectively. Compound 18b also had no detectable toxicity for different human cell lines. Their binding mode and interactions with the RT suggest that there was strong and adaptable binding in a tight (NNRTI) hydrophobic pocket. In summary, this iterative study produced structural clues and led to a group of non-toxic, novel compounds to inhibit HIV-RT with up to nanomolar potency. Copyright © 2016 Elsevier Ltd. All rights reserved.

Purification and Characterization of a Lectin from Phaseolus vulgaris cv. (Anasazi Beans)

PubMed Central

Sharma, Arishya; Ng, Tzi Bun; Wong, Jack Ho; Lin, Peng

2009-01-01

A lectin has been isolated from seeds of the Phaseolus vulgaris cv. “Anasazi beans” using a procedure that involved affinity chromatography on Affi-gel blue gel, fast protein liquid chromatography (FPLC)-ion exchange chromatography on Mono S, and FPLC-gel filtration on Superdex 200. The lectin was comprised of two 30-kDa subunits with substantial N-terminal sequence similarity to other Phaseolus lectins. The hemagglutinating activity of the lectin was stable within the pH range of 1–14 and the temperature range of 0–80°C. The lectin potently suppressed proliferation of MCF-7 (breast cancer) cells with an IC50 of 1.3 μM, and inhibited the activity of HIV-1 reverse transcriptase with an IC50 of 7.6 μM. The lectin evoked a mitogenic response from murine splenocytes as evidenced by an increase in [3H-methyl]-thymidine incorporation. The lectin had no antifungal activity. It did not stimulate nitric oxide production by murine peritoneal macrophages. Chemical modification results indicated that tryptophan was crucial for the hemagglutinating activity of the lectin. PMID:19343172

6-(1-Benzyl-1H-pyrrol-2-yl)-2,4-dioxo-5-hexenoic acids as dual inhibitors of recombinant HIV-1 integrase and ribonuclease H, synthesized by a parallel synthesis approach.

PubMed

Costi, Roberta; Métifiot, Mathieu; Esposito, Francesca; Cuzzucoli Crucitti, Giuliana; Pescatori, Luca; Messore, Antonella; Scipione, Luigi; Tortorella, Silvano; Zinzula, Luca; Novellino, Ettore; Pommier, Yves; Tramontano, Enzo; Marchand, Christophe; Di Santo, Roberto

2013-11-14

The increasing efficiency of HAART has helped to transform HIV/AIDS into a chronic disease. Still, resistance and drug-drug interactions warrant the development of new anti-HIV agents. We previously discovered hit 6, active against HIV-1 replication and targeting RNase H in vitro. Because of its diketo-acid moiety, we speculated that this chemotype could serve to develop dual inhibitors of both RNase H and integrase. Here, we describe a new series of 1-benzyl-pyrrolyl diketohexenoic derivatives, 7a-y and 8a-y, synthesized following a parallel solution-phase approach. Those 50 analogues have been tested on recombinant enzymes (RNase H and integrase) and in cell-based assays. Approximately half (22) exibited inhibition of HIV replication. Compounds 7b, 7u, and 8g were the most active against the RNase H activity of reverse-transcriptase, with IC50 values of 3, 3, and 2.5 μM, respectively. Compound 8g was also the most potent integrase inhibitor with an IC50 value of 26 nM.

Potential of the novel antiretroviral drug rilpivirine to modulate the expression and function of drug transporters and drug-metabolising enzymes in vitro.

PubMed

Weiss, Johanna; Haefeli, Walter Emil

2013-05-01

The objective of this study was to assess the drug-drug interaction potential of the new non-nucleoside reverse transcriptase inhibitor (NNRTI) rilpivirine in vitro. The following were evaluated: P-glycoprotein (P-gp/ABCB1) inhibition by calcein assay; breast cancer resistance protein (BCRP/ABCG2) inhibition by pheophorbide A efflux; and inhibition of organic anion transporting polypeptide (OATP) 1B1 and OATP1B3 by 8-fluorescein-cAMP uptake. Inhibition of cytochrome P450 enzymes was assessed using commercially available kits. Substrate characteristics were evaluated by growth inhibition assays in MDCKII cells overexpressing particular ABC transporters. Induction of drug-metabolising enzymes and transporters was quantified by real-time RT-PCR in LS180 cells, and activation of pregnane X receptor (PXR) by a reporter gene assay. Rilpivirine significantly inhibited P-gp (IC(50) = 13.1 ± 6.8 μmol/L), BCRP (IC(50) = 1.5 ± 0.3 μmol/L), OATP1B1 (IC(50) = 4.1 ± 1.8 μmol/L), OATP1B3 (IC(50) = 6.1 ± 0.9 μmol/L), CYP3A4 (IC(50) = 1.3 ± 0.6 μmol/L), CYP2C19 (IC(50) = 2.7 ± 0.3 μmol/L) and CYP2B6 (IC(50) = 4.2 ± 1.6 μmol/L). Growth inhibition assays indicate that rilpivirine is not a substrate of P-gp, BCRP, or multidrug resistance-associated proteins 1 and 2. In LS180 cells, rilpivirine induced mRNA expression of ABCB1, CYP3A4 and UGT1A3, whereas ABCC1, ABCC2, ABCG2, OATP1B1 and UGT1A9 were not induced. Moreover, rilpivirine was a PXR activator. In conclusion, rilpivirine inhibits and induces several relevant drug-metabolising enzymes and drug transporters, but owing to its low plasma concentrations it is most likely less prone to drug-drug interactions than older NNRTIs. Copyright © 2013 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

A Novel Laccase with Potent Antiproliferative and HIV-1 Reverse Transcriptase Inhibitory Activities from Mycelia of Mushroom Coprinus comatus

PubMed Central

Zhao, Shuang; Rong, Cheng-Bo; Kong, Chang; Liu, Yu; Xu, Feng; Miao, Qian-Jiang; Wang, Shou-Xian; Wang, He-Xiang

2014-01-01

A novel laccase was isolated and purified from fermentation mycelia of mushroom Coprinus comatus with an isolation procedure including three ion-exchange chromatography steps on DEAE-cellulose, CM-cellulose, and Q-Sepharose and one gel-filtration step by fast protein liquid chromatography on Superdex 75. The purified enzyme was a monomeric protein with a molecular weight of 64 kDa. It possessed a unique N-terminal amino acid sequence of AIGPVADLKV, which has considerably high sequence similarity with that of other fungal laccases, but is different from that of C. comatus laccases reported. The enzyme manifested an optimal pH value of 2.0 and an optimal temperature of 60°C using 2,2′-azinobis(3-ethylbenzothiazolone-6-sulfonic acid) diammonium salt (ABTS) as the substrate. The laccase displayed, at pH 2.0 and 37°C, K m values of 1.59 mM towards ABTS. It potently suppressed proliferation of tumor cell lines HepG2 and MCF7, and inhibited human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) with an IC50 value of 3.46 μM, 4.95 μM, and 5.85 μM, respectively, signifying that it is an antipathogenic protein. PMID:25540778

Sargassum fusiforme fraction is a potent and specific inhibitor of HIV-1 fusion and reverse transcriptase

PubMed Central

Paskaleva, Elena E; Lin, Xudong; Duus, Karen; McSharry, James J; Veille, Jean-Claude L; Thornber, Carol; Liu, Yanze; Lee, David Yu-Wei; Canki, Mario

2008-01-01

Sargassum fusiforme (Harvey) Setchell has been shown to be a highly effective inhibitor of HIV-1 infection. To identify its mechanism of action, we performed bioactivity-guided fractionation on Sargassum fusiforme mixture. Here, we report isolation of a bioactive fraction SP4-2 (S. fusiforme), which at 8 μg/ml inhibited HIV-1 infection by 86.9%, with IC50 value of 3.7 μg. That represents 230-fold enhancement of antiretroviral potency as compared to the whole extract. Inhibition was mediated against both CXCR4 (X4) and CCR5 (R5) tropic HIV-1. Specifically, 10 μg/ml SP4-2 blocked HIV-1 fusion and entry by 53%. This effect was reversed by interaction of SP4-2 with sCD4, suggesting that S. fusiforme inhibits HIV-1 infection by blocking CD4 receptor, which also explained observed inhibition of both X4 and R5-tropic HIV-1. SP4-2 also inhibited HIV-1 replication after virus entry, by directly inhibiting HIV-1 reverse transcriptase (RT) in a dose dependent manner by up to 79%. We conclude that the SP4-2 fraction contains at least two distinct and biologically active molecules, one that inhibits HIV-1 fusion by interacting with CD4 receptor, and another that directly inhibits HIV-1 RT. We propose that S. fusiforme is a lead candidate for anti-HIV-1 drug development. PMID:18197976

The design and synthesis of 9-phenylcyclohepta[d]pyrimidine-2,4-dione derivatives as potent non-nucleoside inhibitors of HIV reverse transcriptase.

PubMed

Wang, Xiaowei; Lou, Qinghua; Guo, Ying; Xu, Yang; Zhang, Zhili; Liu, Junyi

2006-09-07

Novel compounds, which can be considered as conformationally restricted analogues of MKC-442, have been synthesized and tested as inhibitors of the reverse transcriptase of human immunodeficiency virus type-1 (HIV-1). Reaction of urea with a beta-ketoester furnished 6,7,8,9-tetrahydro-9-phenyl-1H-cyclohepta[d]pyrimidine-2,4-(3H,5H)-dione (6a) and 6,7,8,9-tetrahydro-9-p-tolyl-1H-cyclohepta[d]pyrimidine-2,4-(3H,5H)-dione (6b) which were then alkylated at the N-1 position with chloromethyl ether, allyl bromide and benzyl bromide to afford the target compounds 7a-b, 8a-b, 9 and 10, respectively. The seven-membered, annelated compounds have a relatively rigid structures and can lock the orientation of the aromatic ring. Chemical modification at N-1 of the pyrinidine ring and the 9-phenyl ring was attempted, with the aim of improving the antiretroviral activity. In particular, replacement of the aliphatic group with the phenyl moiety at the terminus of N-1 side chain can enhance the activity. The most active compounds showed activity in the low micromolar range with IC50 values comparable to that of nevirapine. The biological activity results are in accordance with the docking results.

Role of T-type calcium channels in myogenic tone of skeletal muscle resistance arteries.

PubMed

VanBavel, Ed; Sorop, Oana; Andreasen, Ditte; Pfaffendorf, Martin; Jensen, Boye L

2002-12-01

T-type calcium channels may be involved in the maintenance of myogenic tone. We tested their role in isolated rat cremaster arterioles obtained after CO(2) anesthesia and decapitation. Total RNA was analyzed by RT-PCR and Southern blotting for calcium channel expression. We observed expression of voltage-operated calcium (Ca(V)) channels Ca(V)3.1 (T-type), Ca(V)3.2 (T-type), and Ca(V)1.2 (L-type) in cremaster arterioles (n = 3 rats). Amplification products were observed only in the presence of reverse transcriptase and cDNA. Concentration-response curves of the relatively specific L-type blocker verapamil and the relatively specific T-type blockers mibefradil and nickel were made on cannulated vessels with either myogenic tone (75 mmHg) or a similar level of constriction induced by 30 mM K(+) at 35 mmHg. Mibefradil and nickel were, respectively, 162-fold and 300-fold more potent in inhibiting myogenic tone compared with K(+)-induced constriction [log(IC(50), M): mibefradil, basal -7.3 +/- 0.2 (n = 9) and K(+) -5.1 +/- 0.1 (n = 5); nickel, basal -4.1 +/- 0.2 (n = 5) and K(+) -1.6 +/- 0.5 (n = 5); means +/- SE]. Verapamil had a 17-fold more potent effect [log(IC(50), M): basal -6.6 +/- 0.1 (n = 5); K(+) -5.4 +/- 0.3 (n = 4); all log(IC(50)) P < 0.05, basal vs. K(+)]. These data suggest that T-type calcium channels are expressed and involved in maintenance of myogenic tone in rat cremaster muscle arterioles.

Differential modulation of P-glycoprotein expression and activity by non-nucleoside HIV-1 reverse transcriptase inhibitors in cell culture.

PubMed

Störmer, Elke; von Moltke, Lisa L; Perloff, Michael D; Greenblatt, David J

2002-07-01

This study investigated the effects of the non-nucleoside HIV-1 reverse transcriptase inhibitors (NNRTI) nevirapine (NVR), efavirenz (EFV), and delavirdine (DLV) on P-glycoprotein (P-gp) activity and expression to anticipate P-gp related drug-drug interactions associated with combination therapy. NNRTIs were evaluated as P-gp substrates by measuring differential transport across Caco-2 cell monolayers. Inhibition of P-gp mediated rhodaminel23 (Rh123) transport in Caco-2 cells was used to assess P-gp inhibition by NNRTIs. Induction of P-gp expression and activity in LS180V cells following 3-day exposure to NNRTIs was measured by western blot analysis and cellular Rh123 uptake, respectively. The NNRTIs showed no differential transport between the basolateral to apical and apical to basolateral direction. NNRTI transport in either direction was not affected by the P-gp inhibitor verapamil. DLV inhibited Rh123 transport, causing a reduction to 15% of control at 100 microM (IC50 = 30 microM). NVR caused a concentration-dependent induction of P-gp expression in LS180V cells resulting in a 3.5-fold increase in immunoreactive P-gp at 100 microM NVR. Induction attributable to EFV and DLV was quantitatively smaller. NVR significantly reduced cellular uptake of Rh123 into LS180V cells, indicating increased drug efflux due to induced P-gp activity; effects of EFV and DLV were smaller. Acute DLV treatment of LS180V cells previously induced with NVR or ritonavir did not reverse the decreased Rh123 cell accumulation. NNRTIs show differential effects on P-gp activity and expression in vitro. Clinical studies are required to elucidate the clinical importance of potential drug interactions.

Interaction of HIV-1 reverse transcriptase ribonuclease H with an acylhydrazone inhibitor.

PubMed

Gong, Qingguo; Menon, Lakshmi; Ilina, Tatiana; Miller, Lena G; Ahn, Jinwoo; Parniak, Michael A; Ishima, Rieko

2011-01-01

HIV-1 reverse transcriptase is a bifunctional enzyme, having both DNA polymerase (RNA- and DNA-dependent) and ribonuclease H activities. HIV-1 reverse transcriptase has been an exceptionally important target for antiretroviral therapeutic development, and nearly half of the current clinically used antiretrovirals target reverse transcriptase DNA polymerase. However, no inhibitors of reverse transcriptase ribonuclease H are on the market or in preclinical development. Several drug-like small molecule inhibitors of reverse transcriptase ribonuclease H have been described, but little structural information is available about the interactions between reverse transcriptase ribonuclease H and inhibitors that exhibit antiviral activity. In this report, we describe NMR studies of the interaction of a new ribonuclease H inhibitor, BHMP07, with a catalytically active HIV-1 reverse transcriptase ribonuclease H domain fragment. We carried out solution NMR experiments to identify the interaction interface of BHMP07 with the ribonuclease H domain fragment. Chemical shift changes of backbone amide signals at different BHMP07 concentrations clearly demonstrate that BHMP07 mainly recognizes the substrate handle region in the ribonuclease H fragment. Using ribonuclease H inhibition assays and reverse transcriptase mutants, the binding specificity of BHMP07 was compared with another inhibitor, dihydroxy benzoyl naphthyl hydrazone. Our results provide a structural characterization of the ribonuclease H inhibitor interaction and are likely to be useful for further improvements of the inhibitors. © 2010 John Wiley & Sons A/S.

A novel hemagglutinin with antiproliferative activity against tumor cells from the hallucinogenic mushroom Boletus speciosus.

PubMed

Sun, Jian; Ng, Tzi-Bun; Wang, Hexiang; Zhang, Guoqing

2014-01-01

Little was known about bioactive compounds from the hallucinogenic mushroom Boletus speciosus. In the present study, a hemagglutinin (BSH, B. speciosus hemagglutinin) was isolated from its fruiting bodies and enzymatic properties were also tested. The chromatographic procedure utilized comprised anion exchange chromatography on Q-Sepharose, cation exchange chromatography on CM-Cellulose, cation exchange chromatography on SP-Sepharose, and gel filtration by FPLC on Superdex 75. The hemagglutinin was a homodimer which was estimated to be approximately 31 kDa in size. The activity of BSH was stable up to 60°C, while there was a precipitous drop in activity when the temperature was elevated to 70°C. BSH retained 25% hemagglutinating activity when exposed to 100 mM NaOH and 25 mM HCl. The activity was potently inhibited by 1.25 mM Hg(2+) and slightly inhibited by Fe(2+), Ca(2+), and Pb(2+). None of the sugars tested showed inhibition towards BSH. Its hemagglutinating activity towards human erythrocytes type A, type B, and type AB was higher than type O. The hemagglutinin showed antiproliferative activity towards hepatoma Hep G2 cells and mouse lymphocytic leukemia cells (L1210) in vitro, with IC50 of 4.7 μ M and 7.0 μ M, respectively. It also exhibited HIV-1 reverse transcriptase inhibitory activity with an IC50 of 7.1 μ M.

The mechano-chemistry of a monomeric reverse transcriptase

PubMed Central

Malik, Omri; Khamis, Hadeel; Rudnizky, Sergei

2017-01-01

Abstract Retroviral reverse transcriptase catalyses the synthesis of an integration-competent dsDNA molecule, using as a substrate the viral RNA. Using optical tweezers, we follow the Murine Leukemia Virus reverse transcriptase as it performs strand-displacement polymerization on a template under mechanical force. Our results indicate that reverse transcriptase functions as a Brownian ratchet, with dNTP binding as the rectifying reaction of the ratchet. We also found that reverse transcriptase is a relatively passive enzyme, able to polymerize on structured templates by exploiting their thermal breathing. Finally, our results indicate that the enzyme enters the recently characterized backtracking state from the pre-translocation complex. PMID:29165701

HIV type 1 genotypic variation in an antiretroviral treatment-naive population in southern India.

PubMed

Balakrishnan, Pachamuthu; Kumarasamy, Nagalingeswaran; Kantor, Rami; Solomon, Suniti; Vidya, Sundararajan; Mayer, Kenneth H; Newstein, Michael; Thyagarajan, Sadras P; Katzenstein, David; Ramratnam, Bharat

2005-04-01

Most studies of HIV-1 drug resistance have examined subtype B viruses; fewer data are available from developing countries, where non-B subtypes predominate. We determined the prevalence of mutations at protease and reverse transcriptase drug resistance positions in antiretroviral drug-naive individuals in southern India. The pol region of the genome was amplified from plasma HIV-1 RNA in 50 patients. All sequences clustered with HIV-1 subtype C. All patients had at least one protease and/or RT mutation at a known subtype B drug resistance position. Twenty percent of patients had mutations at major protease inhibitor resistance positions and 100% had mutations at minor protease inhibitor resistance positions. Six percent and 14% of patients had mutations at nucleoside reverse transcriptase inhibitor and/or nonnucleoside reverse transcriptase inhibitor resistance positions, respectively. Larger scale studies need to be undertaken to better define the genotypic variation of circulating Indian subtype C viruses and their potential impact on drug susceptibility and clinical outcome in treated individuals.

Structure-Based Design of Novel Dihydroalkoxybenzyloxopyrimidine Derivatives as Potent Nonnucleoside Inhibitors of the Human Immunodeficiency Virus Reverse Transcriptase

PubMed Central

Sudbeck, Elise A.; Mao, Chen; Vig, Rakesh; Venkatachalam, T. K.; Tuel-Ahlgren, Lisa; Uckun, Fatih M.

1998-01-01

Two highly potent dihydroalkoxybenzyloxopyrimidine (DABO) derivatives targeting the nonnucleoside inhibitor (NNI) binding site of human immunodeficiency virus (HIV) reverse transcriptase (RT) have been designed based on the structure of the NNI binding pocket and tested for anti-HIV activity. Our lead DABO derivative, 5-isopropyl-2-[(methylthiomethyl)thio]-6-(benzyl)-pyrimidin-4-(1H)-one, elicited potent inhibitory activity against purified recombinant HIV RT and abrogated HIV replication in peripheral blood mononuclear cells at nanomolar concentrations (50% inhibitory concentration, <1 nM) but showed no detectable cytotoxicity at concentrations as high as 100 μM. PMID:9835518

Vaginal Microbicide Film Combinations of Two Reverse Transcriptase Inhibitors, EFdA and CSIC, for the Prevention of HIV-1 Sexual Transmission.

PubMed

Zhang, Wei; Hu, Minlu; Shi, Yuan; Gong, Tiantian; Dezzutti, Charlene S; Moncla, Bernard; Sarafianos, Stefan G; Parniak, Michael A; Rohan, Lisa C

2015-09-01

EFdA is a potent nucleoside reverse transcriptase inhibitor (NRTI) with activity against a wide spectrum of wild-type and drug resistant HIV-1 variants. CSIC is a tight-binding non-nucleoside reverse transcriptase inhibitor (NNRTI) with demonstrated anti-HIV properties important for use in topical prevention of HIV transmission. The objective of this study was to develop and characterize film-formulated EFdA and CSIC for use as a female-controlled vaginal microbicide to prevent sexual transmission of HIV. Assessments of EFdA- and CSIC-loaded films included physicochemical characteristics, in vitro cytotoxicity, epithelia integrity studies, compatibility with the normal vaginal Lactobacillus flora and anti-HIV bioactivity evaluations. No significant change in physicochemical properties or biological activity of the combination films were noted during 3 months storage. In vitro cytotoxicity and bioactivity testing showed that 50% cytotoxic concentration (CC50) of either EFdA or CSIC was several orders of magnitude higher than the 50% effective concentration (EC50) values. Film-formulated EFdA and CSIC combination showed additive inhibitory activity against wild type and drug-resistant variants of HIV. Epithelial integrity studies demonstrated that the combination vaginal film had a much lower toxicity to HEC-1A monolayers compared to that of VCF®, a commercial vaginal film product containing nonoxynol-9. Polarized ectocervical explants showed films with drug alone or in combination were effective at preventing HIV infection. Our data suggest that vaginal microbicide films containing a combination of the NRTI EFdA and the NNRTI CSIC have potential to prevent HIV-1 sexual transmission.

Application of Reverse Transcriptase-PCR-DGGE as a rapid method for routine determination of Vibrio spp. in foods.

PubMed

Chahorm, Kanchana; Prakitchaiwattana, Cheunjit

2018-01-02

The aim of this research was to evaluate the feasibility of PCR-DGGE and Reverse Transcriptase-PCR-DGGE techniques for rapid detection of Vibrio species in foods. Primers GC567F and 680R were initially evaluated for amplifying DNA and cDNA of ten references Vibrio species by PCR method. The GC-clamp PCR amplicons were separated according to their sequences by the DGGE using 10% (w/v) polyacrylamide gel containing 45-70% urea and formamide denaturants. Two pair of Vibrio species, which could not be differentiated on the gel, was Vibrio fluvialis - Vibrio furnissii and Vibrio parahaemolyticus - Vibrio harveyi. To determine the detection limit, in the community of 10 reference strains containing the same viable population, distinct DNA bands of 3 species; Vibrio cholerae, Vibrio mimicus and Vibrio alginolyticus were consistently observed by PCR-DGGE technique. In fact, 5 species; Vibrio cholerae, Vibrio mimicus, Vibrio alginolyticus, Vibrio parahaemolyticus and Vibrio fluvialis consistently observed by Reverse Transcriptase-PCR-DGGE. In the community containing different viable population increasing from 10 2 to 10 5 CFU/mL, PCR-DGGE analysis only detected the two most prevalent species, while RT-PCR-DGGE detected the five most prevalent species. Therefore, Reverse Transcriptase-PCR-DGGE was also selected for detection of various Vibrio cell conditions, including viable cell (VC), injured cells from frozen cultures (IVC) and injured cells from frozen cultures with pre-enrichment (PIVC). It was found that cDNA band of all cell conditions gave the same migratory patterns, except that multiple cDNA bands of Plesiomonas shigelloides under IVC and PIVC conditions were found. When Reverse Transcriptase-PCR-DGGE was used for detecting Vibrio parahaemolyticus in the pathogen-spiked food samples, Vibrio parahaemolyticus could be detected in the spiked samples containing at least 10 2 CFU/g of this pathogen. The results obtained also corresponded to standard method (USFDA, 2004). In comparison with the detection of the Vibrio profiles in fourteen food samples using standard method, Reverse Transcriptase-PCR-DGGE resulted in 100%, 75% and 50% similarity in 3, 1 and 6 food samples, respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

Indolylarylsulfones carrying a heterocyclic tail as very potent and broad spectrum HIV-1 non-nucleoside reverse transcriptase inhibitors.

PubMed

Famiglini, Valeria; La Regina, Giuseppe; Coluccia, Antonio; Pelliccia, Sveva; Brancale, Andrea; Maga, Giovanni; Crespan, Emmanuele; Badia, Roger; Riveira-Muñoz, Eva; Esté, José A; Ferretti, Rosella; Cirilli, Roberto; Zamperini, Claudio; Botta, Maurizio; Schols, Dominique; Limongelli, Vittorio; Agostino, Bruno; Novellino, Ettore; Silvestri, Romano

2014-12-11

We synthesized new indolylarylsulfone (IAS) derivatives carrying a heterocyclic tail at the indole-2-carboxamide nitrogen as potential anti-HIV/AIDS agents. Several new IASs yielded EC50 values <1.0 nM against HIV-1 WT and mutant strains in MT-4 cells. The (R)-11 enantiomer proved to be exceptionally potent against the whole viral panel; in the reverse transcriptase (RT) screening assay, it was remarkably superior to NVP and EFV and comparable to ETV. The binding poses were consistent with the one previously described for the IAS non-nucleoside reverse transcriptase inhibitors. Docking studies showed that the methyl group of (R)-11 points toward the cleft created by the K103N mutation, different from the corresponding group of (S)-11. By calculating the solvent-accessible surface, we observed that the exposed area of RT in complex with (S)-11 was larger than the area of the (R)-11 complex. Compounds 6 and 16 and enantiomer (R)-11 represent novel robust lead compounds of the IAS class.

“Dynamic Range” of Inferred Phenotypic HIV Drug Resistance Values in Clinical Practice

PubMed Central

Swenson, Luke C.; Pollock, Graham; Wynhoven, Brian; Mo, Theresa; Dong, Winnie; Hogg, Robert S.; Montaner, Julio S. G.; Harrigan, P. Richard

2011-01-01

Background ‘Virtual’ or inferred phenotypes (vPhenotypes) are commonly used to assess resistance to antiretroviral agents in patients failing therapy. In this study, we provide a clinical context for understanding vPhenotype values. Methods All HIV-infected persons enrolled in the British Columbia Drug Treatment Program with a baseline plasma viral load (pVL) and follow-up genotypic resistance and pVL results were included up to October 29, 2008 (N = 5,277). Change from baseline pVL was determined as a function of Virco vPhenotype, and the “dynamic range” (defined here by the 10th and 90th percentiles for fold-change in IC50 amongst all patients) was estimated from the distribution of vPhenotye fold-changes across the cohort. Results The distribution of vPhenotypes from a large cohort of HIV patients who have failed therapy are presented for all available antiretroviral agents. A maximum change in IC50 of at least 13-fold was observed for all drugs. The dideoxy drugs, tenofovir and most PIs exhibited small “dynamic ranges” with values of <4-fold change observed in >99% of samples. In contrast, zidovudine, lamivudine, emtricitabine and the non-nucleoside reverse transcriptase inihibitors (excluding etravirine) had large dynamic ranges. Conclusion We describe the populational distribution of vPhenotypes such that vPhenotype results can be interpreted relative to other patients in a drug-specific manner. PMID:21390218

A Novel Hemagglutinin with Antiproliferative Activity against Tumor Cells from the Hallucinogenic Mushroom Boletus speciosus

PubMed Central

Ng, Tzi-Bun; Wang, Hexiang; Zhang, Guoqing

2014-01-01

Little was known about bioactive compounds from the hallucinogenic mushroom Boletus speciosus. In the present study, a hemagglutinin (BSH, B. speciosus hemagglutinin) was isolated from its fruiting bodies and enzymatic properties were also tested. The chromatographic procedure utilized comprised anion exchange chromatography on Q-Sepharose, cation exchange chromatography on CM-Cellulose, cation exchange chromatography on SP-Sepharose, and gel filtration by FPLC on Superdex 75. The hemagglutinin was a homodimer which was estimated to be approximately 31 kDa in size. The activity of BSH was stable up to 60°C, while there was a precipitous drop in activity when the temperature was elevated to 70°C. BSH retained 25% hemagglutinating activity when exposed to 100 mM NaOH and 25 mM HCl. The activity was potently inhibited by 1.25 mM Hg2+ and slightly inhibited by Fe2+, Ca2+, and Pb2+. None of the sugars tested showed inhibition towards BSH. Its hemagglutinating activity towards human erythrocytes type A, type B, and type AB was higher than type O. The hemagglutinin showed antiproliferative activity towards hepatoma Hep G2 cells and mouse lymphocytic leukemia cells (L1210) in vitro, with IC50 of 4.7 μM and 7.0 μM, respectively. It also exhibited HIV-1 reverse transcriptase inhibitory activity with an IC50 of 7.1 μM. PMID:24977148

Cost-Effectiveness of the Third-Agent Class in Treatment-Naive Human Immunodeficiency Virus-Infected Patients in Portugal

PubMed Central

Aragão, Filipa; Vera, José; Vaz Pinto, Inês

2012-01-01

Introduction Current Portuguese HIV treatment guidelines recommend initiating antiretroviral therapy with a regimen composed of two Nucleoside Reverse Transcriptase Inhibitors plus one Non-nucleoside Reverse Transcriptase Inhibitor (2NRTI+NNRTI) or two Nucleoside Reverse Transcriptase Inhibitors plus one boosted protease inhibitor (2NRTI+PI/r). Given the lower daily cost of NNRTI as the third agent when compared to the average daily costs of PI/r, it is relevant to estimate the long term impact of each treatment option in the Portuguese context. Methods We developed a microsimulation discrete events model for cost-effectiveness analysis of HIV treatment, simulating individual paths from ART initiation to death. Four driving forces determine the course of events: CD4+ cell count, viral load, resistance and adherence. Distributions of time to event are conditional to individuals’ characteristics and past history. Time to event was modeled using parametric survival analysis using Stata 11®. Disease progression was structured according to therapy lines and the model was parameterized with cohort Portuguese observational data. All resources were valued at 2009 prices. The National Health Service’s perspective was assumed considering a lifetime horizon and a 5% annual discount rate. Results In this analysis, initiating therapy with two Nucleoside Reverse Transcriptase Inhibitors plus one Non-nucleoside Reverse Transcriptase Inhibitor reduces the average number of switches by 17%, saves 19.573€ per individual and increases life expectancy by 1.7 months showing to be a dominant strategy in 57% of the simulations when compared to two Nucleoside Reverse Transcriptase Inhibitors plus one boosted protease inhibitor. Conclusion This study suggests that, when clinically valid, initiating therapy with two Nucleoside Reverse Transcriptase Inhibitors plus one Non-nucleoside Reverse Transcriptase Inhibitor is a cost-saving strategy and equally effective when compared to two Nucleoside Reverse Transcriptase Inhibitors plus one boosted protease inhibitor as the first regimen. PMID:23028618

Vaginal microbicide film combinations of two reverse transcriptase inhibitors, EFdA and CSIC, for the prevention of HIV-1 sexual transmission

PubMed Central

Zhang, Wei; Hu, Minlu; Shi, Yuan; Gong, Tiantian; Dezzutti, Charlene S.; Moncla, Bernard; Sarafianos, Stefan G.; Parniak, Michael A.; Rohan, Lisa C.

2015-01-01

Purpose EFdA is a potent nucleoside reverse transcriptase inhibitor (NRTI) with activity against a wide spectrum of wild-type and drug resistant HIV-1 variants. CSIC is a tight-binding non-nucleoside reverse transcriptase inhibitor (NNRTI) with demonstrated anti-HIV properties important for use in topical prevention of HIV transmission. The objective of this study was to develop and characterize film-formulated EFdA and CSIC for use as a female-controlled vaginal microbicide to prevent sexual transmission of HIV. Methods Assessments of EFdA- and CSIC-loaded films included physicochemical characteristics, in vitro cytotoxicity, epithelia integrity studies, compatibility with the normal vaginal Lactobacillus flora and anti-HIV bioactivity evaluations. Results No significant change in physicochemical properties or biological activity of the combination films were noted during 3 months storage. In vitro cytotoxicity and bioactivity testing showed that 50% cytotoxic concentration (CC50) of either EFdA or CSIC was several orders of magnitude higher than the 50% effective concentration (EC50) values. Film-formulated EFdA and CSIC combination showed additive inhibitory activity against wild type and drug-resistant variants of HIV. Epithelial integrity studies demonstrated that the combination vaginal film had a much lower toxicity to HEC-1A monolayers compared to that of VCF®, a commercial vaginal film product containing nonoxynol-9. Polarized ectocervical explants showed films with drug alone or in combination were effective at preventing HIV infection. Conclusions Our data suggest that vaginal microbicide films containing a combination of the NRTI EFdA and the NNRTI CSIC have potential to prevent HIV-1 sexual transmission. PMID:25794967

Cell surface expression of CCR5 and other host factors influence the inhibition of HIV-1 infection of human lymphocytes by CCR5 ligands

PubMed Central

Ketas, Thomas J.; Kuhmann, Shawn E.; Palmer, Ashley; Zurita, Juan; He, Weijing; Ahuja, Sunil K.; Klasse, Per Johan; Moore, John P.

2007-01-01

Several CCR5 ligands, including small molecules and monoclonal antibodies (MAbs), are being developed as therapies for infection with strains of human immunodeficiency virus type 1 (HIV-1) that use CCR5 for entry (R5 viruses). The efficacy of such therapies could be influenced by inter-individual differences in host factors, such as CCR5 expression levels. To study this, we used peripheral blood mononuclear cells (PBMCs) from humans and rhesus macaques. The half-maximal inhibitory concentrations (IC50) of the small-molecule CCR5 ligands CMPD167, UK427,857 and SCH-D, and of the PRO 140 MAb, differ by >2 logs in a donor-dependent manner. We studied this variation by using flow cytometry to measure CCR5 expression on PBMCs from six of the human donors: the IC50 values of both SCH-D and PRO 140 correlated with CCR5 expression (R2 = 0.64 and 0.99, respectively). We also determined the efficacy of the CCR5 ligands against HIV-1 infection of HeLa-derived cell lines that express CD4 at the same level but vary 2-fold in CCR5 expression (JC.48 and JC.53 cells). The moderately greater CCR5 expression on the JC.53 than the JC.48 cells was associated with proportionately higher median IC50 values for all four CCR5 ligands but not for a soluble CD4-based inhibitor or a non-nucleoside reverse transcriptase inhibitor. We conclude that differences in CCR5 expression on human PBMCs, which can be affected by CCL3L1 gene dose, may influence the antiviral potency of CCR5 ligands in vitro, but other host factors are also likely to be involved. These host factors may affect the clinical activity of CCR5 inhibitors, including their use as topical microbicides to prevent HIV-1 transmission. PMID:17428518

Top-down and bottom-up modeling in system pharmacology to understand clinical efficacy: An example with NRTIs of HIV-1.

PubMed

Duwal, Sulav; von Kleist, Max

2016-10-30

A major aim of Systems Pharmacology is to understand clinically relevant mechanisms of action (MOA) of drugs and to use this knowledge in order to optimize therapy. To enable this mission it is necessary to obtain knowledge on how in vitro testable insights translate into clinical efficacy. Mathematical modeling and data integration are essential components to achieve this goal. Two modeling philosophies are prevalent, each of which in isolation is not sufficient to achieve the above described: In a 'top-down' approach, a minimal pharmacokinetic-pharmacodynamic (PK-PD) model is derived from- and fitted to available clinical data. This model may lack interpretability in terms of mechanisms and may only be predictive for scenarios already covered by the data used to derive it. A 'bottom-up' approach builds on mechanistic insights derived from in vitro/ex vivo experiments, which can be conducted under controlled conditions, but may not be fully representative for the in vivo/clinical situation. In this work, we employ both approaches side-by-side to predict the clinical potency (IC 50 values) of the nucleoside reverse transcriptase inhibitors (NRTIs) lamivudine, emtricitabine and tenofovir. In the 'top-down' approach, this requires to establish the dynamic link between the intracellularly active NRTI-triphosphates (which exert the effect) and plasma prodrug PK and to subsequently link this composite PK model to viral kinetics. The 'bottom-up' approach assesses inhibition of reverse transcriptase-mediated viral DNA polymerization by the intracellular, active NRTI-triphosphates, which has to be brought into the context of target cell infection. By using entirely disparate sets of data to derive and parameterize the respective models, our approach serves as a means to assess the clinical relevance of the 'bottom-up' approach. We obtain very good qualitative and quantitative agreement between 'top-down' vs. 'bottom-up' predicted IC 50 values, arguing for the validity of the 'bottom-up' approach. We noted, however, that the 'top-down' approach is strongly dependent on the sparse and noisy intracellular pharmacokinetic data. All in all, our work provides confidence that we can translate in vitro parameters into measures of clinical efficacy using the 'bottom-up' approach. This may allow to infer the potency of various NRTIs in inhibiting e.g. mutant viruses, to distinguish sources of interaction of NRTI combinations and to assess the efficacy of different NRTIs for repurposing, e.g. for pre-exposure prophylaxis. Copyright © 2016 Elsevier B.V. All rights reserved.

Site-directed mutagenesis of the conserved Asp-443 and Asp-498 carboxy-terminal residues of HIV-1 reverse transcriptase.

PubMed Central

Mizrahi, V; Usdin, M T; Harington, A; Dudding, L R

1990-01-01

Substitution of the conserved Asp-443 residue of HIV-1 reverse transcriptase by asparagine specifically suppressed the ribonuclease H activity of the enzyme without affecting the reverse transcriptase activity, suggesting involvement of this ionizable residue at the ribonuclease H active site. An analogous asparagine substitution of the Asp-498 residue yielded an unstable enzyme that was difficult to enzymatically characterize. However, the instability caused by the Asn-498 mutation was relieved by the introduction of a second distal Asn-443 substitution, yielding an enzyme with wild type reverse transcriptase activity, but lacking ribonuclease H activity. Images PMID:1699202

Characterization of UC781-Tenofovir Combination Gel Products for HIV-1 Infection Prevention in an Ex Vivo Ectocervical Model

PubMed Central

Cost, Marilyn; Dezzutti, Charlene S.; Clark, Meredith R.; Friend, David R.; Akil, Ayman

2012-01-01

HIV continues to be a problem worldwide. Topical vaginal microbicides represent one option being evaluated to stop the spread of HIV. With drug candidates that have a specific action against HIV now being studied, it is important that, when appropriate and based on the mechanism of action, the drug permeates the tissue so that it can be delivered to specific targets which reside there. Novel formulations of the nucleotide reverse transcriptase inhibitor tenofovir (TFV) and the nonnucleoside reverse transcriptase inhibitor UC781 have been developed and evaluated here. Gels with three distinct rheological properties were prepared. The three gels released both UC781 and TFV under in vitro conditions at concentrations equal to or above the reported 50% effective concentrations (EC50s). The drug concentrations in ectocervical tissues were well in excess of the reported EC50s. The gels maintain ectocervical viability and prevent infection of ectocervical explants after a HIV-1 challenge. This study successfully demonstrates the feasibility of using this novel combination of antiretroviral agents in an aqueous gel as an HIV infection preventative. PMID:22430977

In vitro cross-resistance profile of nucleoside reverse transcriptase inhibitor (NRTI) BMS-986001 against known NRTI resistance mutations.

PubMed

Li, Zhufang; Terry, Brian; Olds, William; Protack, Tricia; Deminie, Carol; Minassian, Beatrice; Nowicka-Sans, Beata; Sun, Yongnian; Dicker, Ira; Hwang, Carey; Lataillade, Max; Hanna, George J; Krystal, Mark

2013-11-01

BMS-986001 is a novel HIV nucleoside reverse transcriptase inhibitor (NRTI). To date, little is known about its resistance profile. In order to examine the cross-resistance profile of BMS-986001 to NRTI mutations, a replicating virus system was used to examine specific amino acid mutations known to confer resistance to various NRTIs. In addition, reverse transcriptases from 19 clinical isolates with various NRTI mutations were examined in the Monogram PhenoSense HIV assay. In the site-directed mutagenesis studies, a virus containing a K65R substitution exhibited a 0.4-fold change in 50% effective concentration (EC50) versus the wild type, while the majority of viruses with the Q151M constellation (without M184V) exhibited changes in EC50 versus wild type of 0.23- to 0.48-fold. Susceptibility to BMS-986001 was also maintained in an L74V-containing virus (0.7-fold change), while an M184V-only-containing virus induced a 2- to 3-fold decrease in susceptibility. Increasing numbers of thymidine analog mutation pattern 1 (TAM-1) pathway mutations correlated with decreases in susceptibility to BMS-986001, while viruses with TAM-2 pathway mutations exhibited a 5- to 8-fold decrease in susceptibility, regardless of the number of TAMs. A 22-fold decrease in susceptibility to BMS-986001 was observed in a site-directed mutant containing the T69 insertion complex. Common non-NRTI (NNRTI) mutations had little impact on susceptibility to BMS-986001. The results from the site-directed mutants correlated well with the more complicated genotypes found in NRTI-resistant clinical isolates. Data from clinical studies are needed to determine the clinically relevant resistance cutoff values for BMS-986001.

Perinatal exposure of patas monkeys to antiretroviral nucleoside reverse-transcriptase inhibitors induces genotoxicity persistent for up to 3 years of age.

PubMed

Olivero, Ofelia A; Torres, Lorangelly Rivera; Gorjifard, Sayeh; Momot, Dariya; Marrogi, Eryney; Divi, Rao L; Liu, Yongmin; Woodward, Ruth A; Sowers, Marsha J; Poirier, Miriam C

2013-07-15

Erythrocebus patas (patas) monkeys were used to model antiretroviral (ARV) drug in human immunodeficiency virus type 1-infected pregnant women. Pregnant patas dams were given human-equivalent doses of ARVs daily during 50% of gestation. Mesenchymal cells, cultured from bone marrow of patas offspring obtained at birth and at 1 and 3 years of age, were examined for genotoxicity, including centrosomal amplification, micronuclei, and micronuclei containing whole chromosomes. Compared with controls, statistically significant increases (P < .05) in centrosomal amplification, micronuclei, and micronuclei containing whole chromosomes were found in mesenchymal cells from most groups of offspring at the 3 time points. Transplacental nucleoside reverse-transcriptase inhibitor exposures induced fetal genotoxicity that was persistent for 3 years.

Antiviral Activity of MK-4965, a Novel Nonnucleoside Reverse Transcriptase Inhibitor▿

PubMed Central

Lai, Ming-Tain; Munshi, Vandna; Touch, Sinoeun; Tynebor, Robert M.; Tucker, Thomas J.; McKenna, Philip M.; Williams, Theresa M.; DiStefano, Daniel J.; Hazuda, Daria J.; Miller, Michael D.

2009-01-01

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) are the mainstays of therapy for the treatment of human immunodeficiency virus type 1 (HIV-1) infections. However, the effectiveness of NNRTIs can be hampered by the development of resistance mutations which confer cross-resistance to drugs in the same class. Extensive efforts have been made to identify new NNRTIs that can suppress the replication of the prevalent NNRTI-resistant viruses. MK-4965 is a novel NNRTI that possesses both diaryl ether and indazole moieties. The compound displays potency at subnanomolar concentrations against wild-type (WT), K103N, and Y181C reverse transcriptase (RT) in biochemical assays. MK-4965 is also highly potent against the WT virus and two most prevalent NNRTI-resistant viruses (viruses that harbor the K103N or the Y181C mutation), against which it had 95% effective concentrations (EC95s) of <30 nM in the presence of 10% fetal bovine serum. The antiviral EC95 of MK-4965 was reduced approximately four- to sixfold when it was tested in 50% human serum. Moreover, MK-4965 was evaluated with a panel of 15 viruses with NNRTI resistance-associated mutations and showed a superior mutant profile to that of efavirenz but not to that of etravirine. MK-4965 was similarly effective against various HIV-1 subtypes and viruses containing nucleoside reverse transcriptase inhibitor or protease inhibitor resistance-conferring mutations. A two-drug combination study showed that the antiviral activity of MK-4965 was nonantagonistic with each of the 18 FDA-licensed drugs tested vice versa in the present study. Taken together, these in vitro data show that MK-4965 possesses the desired properties for further development as a new NNRTI for the treatment of HIV-1 infection. PMID:19289522

The Discovery of Reverse Transcriptase.

PubMed

Coffin, John M; Fan, Hung

2016-09-29

In 1970 the independent and simultaneous discovery of reverse transcriptase in retroviruses (then RNA tumor viruses) by David Baltimore and Howard Temin revolutionized molecular biology and laid the foundations for retrovirology and cancer biology. In this historical review we describe the formulation of the controversial provirus hypothesis by Temin, which ultimately was proven by his discovery of reverse transcriptase in Rous sarcoma virus virions. Baltimore arrived at the same discovery through his studies on replication of RNA-containing viruses, starting with poliovirus and then moving to vesicular stomatitis virus, where he discovered a virion RNA polymerase. Subsequent studies of reverse transcriptase led to the elucidation of the mechanism of retrovirus replication, the discovery of oncogenes, the advent of molecular cloning, the search for human cancer viruses, and the discovery and treatment of HIV/AIDS.

The HEPT Analogue WPR-6 Is Active against a Broad Spectrum of Nonnucleoside Reverse Transcriptase Drug-Resistant HIV-1 Strains of Different Serotypes.

PubMed

Xu, Weisi; Zhao, Jianxiong; Sun, Jianping; Yin, Qianqian; Wang, Yan; Jiao, Yang; Liu, Junyi; Jiang, Shibo; Shao, Yiming; Wang, Xiaowei; Ma, Liying

2015-08-01

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) are important components of the highly active antiretroviral therapy (HAART) used to treat human immunodeficiency type 1 virus (HIV-1). However, because of the emergence of drug resistance and the adverse effects of current anti-HIV drugs, it is essential to develop novel NNRTIs with an excellent safety profile, improved activity against NNRTI-resistant viruses, and enhanced activity against clinical isolates of different subtypes. Here, we have identified 1-[(benzyloxy)methyl]-6-(3,5-dimethylbenzyl)-5-iodopyrimidine-2,4(1H,3H)-dione (WPR-6), a novel NNRTI with a 50% effective concentration (EC50) of 2 to 4 nM against laboratory-adapted HIV-1 strain SF33 and an EC50 of 7 to 14 nM against nucleoside reverse transcriptase inhibitor-resistant HIV-1 strain 7391 with a therapeutic index of >1 × 10(4). A panel of five representative clinical virus isolates of different subtypes circulating predominantly in China was highly sensitive to WPR-6, with EC50s ranging from 1 to 6 nM. In addition, WPR-6 showed excellent antiviral potency against the most prevalent NNRTI-resistant viruses containing the K103N and Y181C mutations. To determine whether WPR-6 selects for novel resistant mutants, in vitro resistance selection was conducted with laboratory-adapted HIV-1 strain SF33 on MT-4 cells. The results demonstrated that V106I and Y188L were the two dominant NNRTI-associated resistance mutations detected in the breakthrough viruses. Taken together, these in vitro data indicate that WPR-6 has greater efficacy than the reference HEPT analogue TNK651 and the marketed drug nevirapine against HIV-1. However, to develop it as a new NNRTI, further improvement of its pharmacological properties is warranted. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Enzyme engineering through evolution: thermostable recombinant group II intron reverse transcriptases provide new tools for RNA research and biotechnology.

PubMed

Collins, Kathleen; Nilsen, Timothy W

2013-08-01

Current investigation of RNA transcriptomes relies heavily on the use of retroviral reverse transcriptases. It is well known that these enzymes have many limitations because of their intrinsic properties. This commentary highlights the recent biochemical characterization of a new family of reverse transcriptases, those encoded by group II intron retrohoming elements. The novel properties of these enzymes endow them with the potential to revolutionize how we approach RNA analyses.

Nucleoside reverse transcriptase inhibitors possess intrinsic anti-inflammatory activity

PubMed Central

Fowler, Benjamin J.; Gelfand, Bradley D.; Kim, Younghee; Kerur, Nagaraj; Tarallo, Valeria; Hirano, Yoshio; Amarnath, Shoba; Fowler, Daniel H.; Radwan, Marta; Young, Mark T.; Pittman, Keir; Kubes, Paul; Agarwal, Hitesh K.; Parang, Keykavous A.; Hinton, David R.; Bastos-Carvalho, Ana; Li, Shengjian; Yasuma, Tetsuhiro; Mizutani, Takeshi; Yasuma, Reo; Wright, Charles; Ambati, Jayakrishna

2014-01-01

Nucleoside reverse transcriptase inhibitors (NRTIs) are mainstay therapeutics for HIV that block retrovirus replication. Alu (an endogenous retroelement that also requires reverse transcriptase for its life cycle)-derived RNAs activate P2X7 and the NLRP3 inflammasome to cause cell death of the retinal pigment epithelium (RPE) in geographic atrophy, a type of age-related macular degeneration. We found that NRTIs inhibit P2X7-mediated NLRP3 inflammasome activation independent of reverse transcriptase inhibition. Multiple approved and clinically relevant NRTIs prevented caspase-1 activation, the effector of the NLRP3 inflammasome, induced by Alu RNA. NRTIs were efficacious in mouse models of geographic atrophy, choroidal neovascularization, graft-versus-host disease (GVHD), and sterile liver inflammation. Our findings suggest that NRTIs are ripe for drug repurposing in P2X7-driven diseases. PMID:25414314

Evidence for retrovirus infections in green turtles Chelonia mydas from the Hawaiian islands

USGS Publications Warehouse

Casey, R.N.; Quackenbush, S.L.; Work, Thierry M.; Balazs, G.H.; Bowser, P.R.; Casey, J.W.

1997-01-01

Apparently normal Hawaiian green turtles Chelonia mydas and those displaying fibropapillomas were analyzed for infection by retroviruses. Strikingly, all samples were positive for polymerase enhanced reverse transcriptase (PERT) with levels high enough to quantitate by the conventional reverse transcriptase (RT) assay. However, samples of skin, even from asymptomatic turtles, were RT positive, although the levels of enzyme activity in healthy turtles hatched and raised in captivity were much lower than those observed in asymptomatic free-ranging turtles. Turtles with fibropapillomas displayed a broad range of reverse transcriptase activity. Skin and eye fibropapillomas and a heart tumor were further analyzed and shown to have reverse transcriptase activity that banded in a sucrose gradient at 1.17 g ml-1. The reverse transcriptase activity purified from the heart tumor displayed a temperature optimum of 37??C and showed a preference for Mn2+ over Mg2+. Sucrose gradient fractions of this sample displaying elevated reverse transcriptase activity contained primarily retrovitalsized particles with prominent envelope spikes, when negatively stained and examined by electron microscopy. Sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of gradient-purified virions revealed a conserved profile among 4 independent tumors and showed 7 prominent proteins having molecular weights of 116, 83, 51, 43, 40, 20 and 14 kDa. The data suggest that retroviral infections are widespread in Hawaiian green turtles and a comprehensive investigation is warranted to address the possibility that these agents cause green turtle fibropapillomatosis (GTFP).

Cytotoxic and HIV-1 enzyme inhibitory activities of Red Sea marine organisms.

PubMed

Ellithey, Mona S; Lall, Namrita; Hussein, Ahmed A; Meyer, Debra

2014-02-25

Cancer and HIV/AIDS are two of the greatest public health and humanitarian challenges facing the world today. Infection with HIV not only weakens the immune system leading to AIDS and increasing the risk of opportunistic infections, but also increases the risk of several types of cancer. The enormous biodiversity of marine habitats is mirrored by the molecular diversity of secondary metabolites found in marine animals, plants and microbes which is why this work was designed to assess the anti-HIV and cytotoxic activities of some marine organisms of the Red Sea. The lipophilic fractions of methanolic extracts of thirteen marine organisms collected from the Red Sea (Egypt) were screened for cytotoxicity against two human cancer cell lines; leukaemia (U937) and cervical cancer (HeLa) cells. African green monkey kidney cells (Vero) were used as normal non-malignant control cells. The extracts were also tested for their inhibitory activity against HIV-1 enzymes, reverse transcriptase (RT) and protease (PR). Cytotoxicity results showed strong activity of the Cnidarian Litophyton arboreum against U-937 (IC50; 6.5 μg/ml ±2.3) with a selectivity index (SI) of 6.45, while the Cnidarian Sarcophyton trochliophorum showed strong activity against HeLa cells (IC50; 5.2 μg/ml ±1.2) with an SI of 2.09. Other species showed moderate to weak cytotoxicity against both cell lines. Two extracts showed potent inhibitory activity against HIV-1 protease; these were the Cnidarian jelly fish Cassiopia andromeda (IC50; 0.84 μg/ml ±0.05) and the red algae Galaxura filamentosa (2.6 μg/ml ±1.29). It is interesting to note that the most active extracts against HIV-1 PR, C. andromeda and G. filamentosa showed no cytotoxicity in the three cell lines at the highest concentration tested (100 μg/ml). The strong cytotoxicity of the soft corals L. arboreum and S. trochliophorum as well as the anti-PR activity of the jelly fish C. andromeda and the red algae G. filamentosa suggests the medicinal potential of crude extracts of these marine organisms.

In vitro anti-HIV and antioxidant activity of Hoodia gordonii (Apocynaceae), a commercial plant product.

PubMed

Kapewangolo, Petrina; Knott, Michael; Shithigona, Regina E K; Uusiku, Sylvia L; Kandawa-Schulz, Martha

2016-10-24

Hoodia gordonii products are widely commercialized for anti-obesity purposes; however, minimal research is available on the other health properties demonstrated by this popular herbal plant. H. gordonii crude extracts (ethanol and ethyl acetate) were assayed for in vitro anti-HIV-1 protease (PR), reverse transcriptase (RT) and integrase activity. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) and reducing power assays were used for the antioxidant analysis. In addition, qualitative and quantitative phytochemical analyses of the extracts were determined using standard methods. H. gordonii extract demonstrated good inhibition against HIV RT with IC 50 values of 73.55 ± 0.04 and 69.81 ± 9.45 μg/mL for ethanol and ethyl acetate extracts, respectively. Both extracts also demonstrated inhibitory activity against HIV PR with IC 50 values of 97.29 ± 0.01 and 63.76 ± 9.01 μg/mL for ethanol and ethyl acetate extracts. In addition, H. gordonii also showed good antioxidant activity with IC 50 values of 124.6 ± 11.3 and 126.2 ± 3.15 μg/mL obtained for ethanol and ethyl acetate extracts, respectively. The reducing power of H. gordonii extracts increased as the concentration increased which confirmed the presence of antioxidants (reductants) in the extracts. Phytochemical screening of H. gordonii revealed the presence of phenolics, alkaloids, terpenes, steroids, cardiac glycosides and tannins in the ethanolic extract, while the ethyl acetate extract only showed the presence of phenolics, cardiac glycosides and steroids. The total phenolic content was 420 ± 0.17 and 319.9 ± 0.2 mg GAE/g for the ethanol and ethyl acetate extracts, respectively. The ethanol extract, which revealed the presence of tannins, had a tannin content of 330 ± 0.2 mg TAE/g extract. This data suggests that H. gordonii has good in vitro inhibition against selected HIV-1 enzymes as well as antioxidant properties, suggesting new potential uses for this commercial plant.

Cytotoxic and HIV-1 enzyme inhibitory activities of Red Sea marine organisms

PubMed Central

2014-01-01

Background Cancer and HIV/AIDS are two of the greatest public health and humanitarian challenges facing the world today. Infection with HIV not only weakens the immune system leading to AIDS and increasing the risk of opportunistic infections, but also increases the risk of several types of cancer. The enormous biodiversity of marine habitats is mirrored by the molecular diversity of secondary metabolites found in marine animals, plants and microbes which is why this work was designed to assess the anti-HIV and cytotoxic activities of some marine organisms of the Red Sea. Methods The lipophilic fractions of methanolic extracts of thirteen marine organisms collected from the Red Sea (Egypt) were screened for cytotoxicity against two human cancer cell lines; leukaemia (U937) and cervical cancer (HeLa) cells. African green monkey kidney cells (Vero) were used as normal non-malignant control cells. The extracts were also tested for their inhibitory activity against HIV-1 enzymes, reverse transcriptase (RT) and protease (PR). Results Cytotoxicity results showed strong activity of the Cnidarian Litophyton arboreum against U-937 (IC50; 6.5 μg/ml ±2.3) with a selectivity index (SI) of 6.45, while the Cnidarian Sarcophyton trochliophorum showed strong activity against HeLa cells (IC50; 5.2 μg/ml ±1.2) with an SI of 2.09. Other species showed moderate to weak cytotoxicity against both cell lines. Two extracts showed potent inhibitory activity against HIV-1 protease; these were the Cnidarian jelly fish Cassiopia andromeda (IC50; 0.84 μg/ml ±0.05) and the red algae Galaxura filamentosa (2.6 μg/ml ±1.29). It is interesting to note that the most active extracts against HIV-1 PR, C. andromeda and G. filamentosa showed no cytotoxicity in the three cell lines at the highest concentration tested (100 μg/ml). Conclusion The strong cytotoxicity of the soft corals L. arboreum and S. trochliophorum as well as the anti-PR activity of the jelly fish C. andromeda and the red algae G. filamentosa suggests the medicinal potential of crude extracts of these marine organisms. PMID:24568567

Design, synthesis, and pharmacological evaluation of 2-amino-5-nitrothiazole derived semicarbazones as dual inhibitors of monoamine oxidase and cholinesterase: effect of the size of aryl binding site.

PubMed

Tripathi, Rati K P; M Sasi, Vishnu; Gupta, Sukesh K; Krishnamurthy, Sairam; Ayyannan, Senthil R

2018-12-01

A series of 2-amino-5-nitrothiazole derived semicarbazones were designed, synthesised and investigated for MAO and ChE inhibition properties. Most of the compounds showed preferential inhibition towards MAO-B. Compound 4, (1-(1-(4-Bromophenyl)ethylidene)-4-(5-nitrothiazol-2-yl)semicarbazide) emerged as lead candidate (IC 50  = 0.212 µM, SI = 331.04) against MAO-B; whereas compounds 21 1-(5-Bromo-2-oxoindolin-3-ylidene)-4-(5-nitrothiazol-2-yl)semicarbazide (IC 50  = 0.264 µM) and 17 1-((4-Chlorophenyl) (phenyl)methylene)-4-(5-nitrothiazol-2-yl)semicarbazide (IC 50  = 0.024 µM) emerged as lead AChE and BuChE inhibitors respectively; with activity of compound 21 almost equivalent to tacrine. Kinetic studies indicated that compound 4 exhibited competitive and reversible MAO-B inhibition while compounds 21 and 17 showed mixed-type of AChE and BuChE inhibition respectively. Docking studies revealed that these compounds were well-accommodated within MAO-B and ChE active sites through stable hydrogen bonding and/or hydrophobic interactions. This study revealed the requirement of small heteroaryl ring at amino terminal of semicarbazone template for preferential inhibition and selectivity towards MAO-B. Our results suggest that 5-nitrothiazole derived semicarbazones could be further exploited for its multi-targeted role in development of anti-neurodegenerative agents. [Formula: see text] A library of 2-amino-5-nitrothiazole derived semicarbazones (4-21) was designed, synthesised and evaluated for in vitro MAO and ChE inhibitory activity. Compounds 4, 21 and 17 (shown) have emerged as lead MAO-B (IC 50 :0.212 µM, competitive and reversible), AChE (IC 50 :0.264 µM, mixed and reversible) and BuChE (IC 50 :0.024 µM, mixed and reversible) inhibitor respectively. SAR studies disclosed several structural aspects significant for potency and selectivity and indicated the role of size of aryl binding site in potency and selectivity towards MAO-B. Antioxidant activity and neurotoxicity screening results further suggested their multifunctional potential for the therapy of neurodegenerative diseases.

The discovery of novel diarylpyri(mi)dine derivatives with high level activity against a wide variety of HIV-1 strains as well as against HIV-2.

PubMed

Lu, Xueyi; Yang, Jiapei; Kang, Dongwei; Gao, Ping; Daelemans, Dirk; De Clercq, Erik; Pannecouque, Christophe; Zhan, Peng; Liu, Xinyong

2018-05-01

By means of structure-based molecular hybridization strategy, a series of novel diarylpyri(mi)dine derivatives targeting the entrance channel of HIV-1 reverse transcriptase (RT) were designed, synthesized and evaluated as potent non-nucleoside reverse transcriptase inhibitors (NNRTIs). Encouragingly, all the tested compounds showed good activities against wild-type (WT) HIV-1 (IIIB) with EC 50 in the range of 1.36 nM-29 nM, which is much better than those of nevirapine (NVP, EC 50  = 125.42 nM) and azidothymidine (AZT, EC 50  = 11.36 nM). Remarkably, these compounds also displayed effective activity against the most of the single and double-mutated HIV-1 strains with low EC 50 values, which is comparable to the control drugs. Besides, these compounds were also exhibited favorable enzymatic inhibitory activity. Moreover, preliminary structure-activity relationships (SARs) and molecular modeling study were investigated and discussed in detail. Unexpectedly, four diarylpyrimidines yielded moderate anti-HIV-2 activities. To our knowledge, this is rarely reported that diarylpyrimidine-based NNRTIs have potent activity against both HIV-1 and HIV-2 in cell culture. Copyright © 2018 Elsevier Ltd. All rights reserved.

Base modifications affecting RNA polymerase and reverse transcriptase fidelity.

PubMed

Potapov, Vladimir; Fu, Xiaoqing; Dai, Nan; Corrêa, Ivan R; Tanner, Nathan A; Ong, Jennifer L

2018-06-20

Ribonucleic acid (RNA) is capable of hosting a variety of chemically diverse modifications, in both naturally-occurring post-transcriptional modifications and artificial chemical modifications used to expand the functionality of RNA. However, few studies have addressed how base modifications affect RNA polymerase and reverse transcriptase activity and fidelity. Here, we describe the fidelity of RNA synthesis and reverse transcription of modified ribonucleotides using an assay based on Pacific Biosciences Single Molecule Real-Time sequencing. Several modified bases, including methylated (m6A, m5C and m5U), hydroxymethylated (hm5U) and isomeric bases (pseudouridine), were examined. By comparing each modified base to the equivalent unmodified RNA base, we can determine how the modification affected cumulative RNA polymerase and reverse transcriptase fidelity. 5-hydroxymethyluridine and N6-methyladenosine both increased the combined error rate of T7 RNA polymerase and reverse transcriptases, while pseudouridine specifically increased the error rate of RNA synthesis by T7 RNA polymerase. In addition, we examined the frequency, mutational spectrum and sequence context of reverse transcription errors on DNA templates from an analysis of second strand DNA synthesis.

Copper Status of Exposed Microorganisms Influences Susceptibility to Metallic Nanoparticles

PubMed Central

Reyes, Vincent C.; Spitzmiller, Melissa R.; Hong-Hermesdorf, Anne; Kropat, Janette; Damoiseaux, Robert D.; Merchant, Sabeeha S.; Mahendra, Shaily

2017-01-01

Although interactions of metallic nanoparticles (NP) with various microorganisms have been previously explored, few studies have examined how metal sensitivity impacts NP toxicity. Herein, we investigated the effects of copper nanoparticles’ (Cu-NPs) exposure to the model alga, Chlamydomonas reinhardtii, in the presence and absence of the essential micronutrient copper. The toxic ranges for Cu-NPs and the ionic control, CuCl2, were determined using a high-throughput ATP-based fluorescence assay. Cu-NPs caused similar mortality in copper-replete and copper-deplete cells (IC50: 14–16 mg/L), but were less toxic than the ionic control, CuCl2 (IC50: 7 mg/L). Using this concentration range, we assessed Cu-NP impacts to cell morphology, copper accumulation, chlorophyll content, and expression of stress genes under both copper supply states. Osmotic swelling, membrane damage, and chloroplast and organelle disintegration were observed by transmission electron microscopy at both conditions. Despite these similarities, copper-deplete cells showed greater accumulation of loosely bound and tightly bound copper after exposure to Cu-NPs. Furthermore, copper-replete cells experienced greater loss of chlorophyll content, 19 % for Cu-NPs, compared to only an 11% net decrease in copper-deplete cells. The tightly bound copper was bioavailable as assessed by reverse-transcriptase quantitative PCR analysis of CYC6, a biomarker for Cu-deficiency. The increased resistance of copper-deplete cells to Cu-NPs suggests that these cells potentially metabolize excess Cu-NPs or better manage sudden influxes of ions. Our findings recommend that toxicity assessments must account for the nutritional status of impacted organisms and use toxicity models based on estimations of the bioavailable fractions. PMID:26387648

An immortalized goat mammary epithelial cell line induced with human telomerase reverse transcriptase (hTERT) gene transfer.

PubMed

He, Y L; Wu, Y H; He, X N; Liu, F J; He, X Y; Zhang, Y

2009-06-01

Although mammary epithelial cell lines can provide a rapid and reliable indicator of gene expression efficiency of transgenic animals, their short lifespan greatly limits this application. To provide stable and long lifespan cells, goat mammary epithelial cells (GMECs) were transduced with pLNCX2-hTERT by retrovirus-mediated gene transfer. Transduced GMECs were evaluated by reverse transcriptase polymerase chain reaction (RT-PCR), proliferation assays, karyotype analysis, telomerase activity assay, western blotting, soft agar assay, and injection into nude mice. Non-transduced GMECs were used as a control. The hTERT-GMECs had higher telomerase activity and extended proliferative lifespan compared to non-transfected GMECs; even after Passage 50, hTERT-GMECs had a near diploid complement of chromosomes. Furthermore, they did not gain the anchorage-independent growth property and were not associated with a malignant phenotype in vitro or in vivo.

Soft shell clams Mya arenaria with disseminated neoplasia demonstrate reverse transcriptase activity

USGS Publications Warehouse

House, M.L.; Kim, C.H.; Reno, P.W.

1998-01-01

Disseminated neoplasia (DN), a proliferative cell disorder of the circulatory system of bivalves, was first reported in oysters in 1969. Since that time, the disease has been determined to be transmissible through water-borne exposure, but the etiological agent has not been unequivocally identified. In order to determine if a viral agent, possibly a retrovirus, could be the causative agent of DN, transmission experiments were performed, using both a cell-free filtrate and a sucrose gradient-purified preparation of a cell-free filtrate of DN positive materials. Additionally, a PCR-enhanced reverse transcriptase assay was used to determine if reverse transcriptase was present in tissues or hemolymph from DN positive soft shell clams Mya arenaria. DN was transmitted to healthy clams by injection with whole DN cells, but not with cell-free flitrates prepared from either tissues from DN positive clams, or DN cells. The cell-free preparations from DN-positive tissues and hemolymph having high levels of DN cells in circulation exhibited positive reactions in the PCR-enhanced reverse transcriptase assay. Cell-free preparations of hemolymph from clams having low levels of DN (<0.1% of cells abnormal), hemocytes from normal soft shell clams, and normal soft shell clam tissues did not produce a positive reaction in the PCR enhanced reverse transcriptase assay.

The Need for Development of New HIV-1 Reverse Transcriptase and Integrase Inhibitors in the Aftermath of Antiviral Drug Resistance

PubMed Central

Wainberg, Mark A.

2012-01-01

The use of highly active antiretroviral therapy (HAART) involves combinations of drugs to achieve maximal virological response and reduce the potential for the emergence of antiviral resistance. There are two broad classes of reverse transcriptase inhibitors, the nucleoside reverse transcriptase inhibitors (NRTIs) and nonnucleoside reverse transcriptase inhibitors (NNRTIs). Since the first classes of such compounds were developed, viral resistance against them has necessitated the continuous development of novel compounds within each class. This paper considers the NRTIs and NNRTIs currently in both preclinical and clinical development or approved for second line therapy and describes the patterns of resistance associated with their use, as well as the underlying mechanisms that have been described. Due to reasons of both affordability and availability, some reverse transcriptase inhibitors with low genetic barrier are more commonly used in resource-limited settings. Their use results to the emergence of specific patterns of antiviral resistance and so may require specific actions to preserve therapeutic options for patients in such settings. More recently, the advent of integrase strand transfer inhibitors represents another major step forward toward control of HIV infection, but these compounds are also susceptible to problems of HIV drug resistance. PMID:24278679

Simple and simultaneous determination of the hiv-protease inhibitors amprenavir, atazanavir, indinavir, lopinavir, nelfinavir, ritonavir and saquinavir plus M8 nelfinavir metabolite and the nonnucleoside reverse transcriptase inhibitors efavirenz and nevirapine in human plasma by reversed-phase liquid chromatography.

PubMed

Poirier, Jean-Marie; Robidou, Pascal; Jaillon, Patrice

2005-04-01

Several studies suggest that therapeutic drug monitoring of protease inhibitors and nonnucleoside reverse transcriptase inhibitors may contribute to the clinical outcome of HIV-infected patients. Because of the growing number of antiretroviral drugs and of drug combinations than can be administered to these patients, an accurate high-performance liquid chromatographic (HPLC) method allowing the simultaneous determination of these drugs may be useful. To date, the authors present the first simultaneous HPLC determination of the new protease inhibitor atazanavir with all the others currently in use (M8 nelfinavir metabolite included) and the 2 widely used nonnucleoside reverse transcriptase inhibitors efavirenz and nevirapine. This simple HPLC method allows the analysis all these drugs at a single ultraviolet wavelength following a 1-step liquid-liquid extraction procedure. A 500-muL plasma sample was spiked with internal standard and subjected to liquid-liquid extraction using by diethyl ether at pH 10. HPLC was performed using a Symmetry Shield RP18 and gradient elution. All the drugs of interest and internal standard were detected with ultraviolet detection at 210 nm. Calibration curves were linear in the range 50-10,000 ng/mL. The observed concentrations of the quality controls at plasma concentrations ranging from 50 to 5000 ng/mL for these drugs showed that the overall accuracy varied from 92% to 104% and 92% to 106% for intraday and day-to-day analysis, respectively. No metabolites of the assayed compounds or other drugs commonly coadministered to HIV-positive patients were found to coelute with the drugs of interest or with the internal standard. This assay was developed for the purpose of therapeutic monitoring (TDM) in HIV-infected patients.

Plasmodium falciparum and Plasmodium vivax Demonstrate Contrasting Chloroquine Resistance Reversal Phenotypes.

PubMed

Wirjanata, Grennady; Handayuni, Irene; Prayoga, Pak; Leonardo, Leo; Apriyanti, Dwi; Trianty, Leily; Wandosa, Ruland; Gobay, Basbak; Kenangalem, Enny; Poespoprodjo, Jeanne Rini; Noviyanti, Rintis; Kyle, Dennis E; Cheng, Qin; Price, Ric N; Marfurt, Jutta

2017-08-01

High-grade chloroquine (CQ) resistance has emerged in both Plasmodium falciparum and P. vivax The aim of the present study was to investigate the phenotypic differences of CQ resistance in both of these species and the ability of known CQ resistance reversal agents (CQRRAs) to alter CQ susceptibility. Between April 2015 and April 2016, the potential of verapamil (VP), mibefradil (MF), L703,606 (L7), and primaquine (PQ) to reverse CQ resistance was assessed in 46 P. falciparum and 34 P. vivax clinical isolates in Papua, Indonesia, where CQ resistance is present in both species, using a modified schizont maturation assay. In P. falciparum , CQ 50% inhibitory concentrations (IC 50 s) were reduced when CQ was combined with VP (1.4-fold), MF (1.2-fold), L7 (4.2-fold), or PQ (1.8-fold). The degree of CQ resistance reversal in P. falciparum was highly correlated with CQ susceptibility for all CQRRAs ( R 2 = 0.951, 0.852, 0.962, and 0.901 for VP, MF, L7, and PQ, respectively), in line with observations in P. falciparum laboratory strains. In contrast, no reduction in the CQ IC 50 s was observed with any of the CQRRAs in P. vivax , even in those isolates with high chloroquine IC 50 s. The differential effect of CQRRAs in P. falciparum and P. vivax suggests significant differences in CQ kinetics and, potentially, the likely mechanism of CQ resistance between these two species. © Crown copyright 2017.

Effects of pyrogallol, hydroquinone and duroquinone on responses to nitrergic nerve stimulation and NO in the rat anococcygeus muscle

PubMed Central

La, Mylinh; Rand, Michael J

1999-01-01

The hypothesis that endogenous superoxide dismutase (SOD) protects the nitrergic transmitter from inactivation by superoxide and that this explains the lack of sensitivity of the transmitter to superoxide generators was tested in the rat isolated anococcygeus muscle.Responses to nitrergic nerve stimulation or to NO were not significantly affected by exogenous SOD or by the Cu/Zn SOD inhibitor diethyldithiocarbamic acid (DETCA).Hydroquinone produced a concentration-dependent reduction of responses to NO with an IC50 of 27 μM, and higher concentrations reduced relaxant responses to nitrergic nerve stimulation with an IC50 of 612 μM. The effects of hydroquinone were only slightly reversed by SOD, so it does not appear to be acting as a superoxide generator.Pyrogallol produced a concentration-dependent reduction in responses to NO with an IC50 value of 39 μM and this effect was reversed by SOD (100–1000 u ml−1). Pyrogallol did not affect responses to nitrergic nerve stimulation. Treatment with DETCA did not alter the differentiating action of pyrogallol.Duroquinone produced a concentration-dependent reduction of relaxations to NO with an IC50 value of 240 μM and 100 μM slightly decreased nitrergic relaxations. After treatment with DETCA, duroquinone produced greater reductions of relaxant responses to NO and to nitrergic stimulation, the IC50 values being 8.5 μM for NO and 40 μM for nitrergic nerve stimulation: these reductions were reversed by SOD.The findings do not support the hypothesis that the presence of Cu/Zn SOD explains the greater susceptibility of NO than the nitrergic transmitter to the superoxide generator pyrogallol, but suggest that it may play a role in the effects of duroquinone. PMID:10051154

Naringin Ameliorates HIV-1 Nucleoside Reverse Transcriptase Inhibitors- Induced Mitochondrial Toxicity.

PubMed

Oluwafeyisetan, Adebiyi; Olubunmi, Adebiyi; Peter, Owira

2016-01-01

Mitochondrial reactive oxygen species (ROS) generation and defective oxidative phosphorylation (OXPHOS) have been proposed as possible mechanisms underlying the development of nucleoside reverse transcriptase inhibitors (NRTIs)-induced mitochondrial toxicities. Available options in managing these complications have, so far, produced controversial results, thus necessitating further research into newer agents with promise. Antioxidant and free-radical scavenging effects of naringin, a plant-derived flavonoid, have previously been demonstrated. This study was designed to investigate the effects of naringin on NRTIs-induced mitochondrial toxicity. Wistar rats were randomly divided into Zidovudine (AZT)-only (100 mg/kg body weight BW); AZT+Naringin (100+50 mg/kg BW); AZT+Vitamin E (100+100 mg/kg BW); Stavudine (d4T)- only (50 mg/kg BW); d4T+Naringin (50+50 mg/kg BW); d4T+Vitamin E (50+100 mg/kg BW) and Vehicle (3.0 mL/kg BW)-treated groups, respectively. After 56 days of oral daily dosing, rats were euthanized by halothane overdose, blood collected by cardiac puncture and livers promptly excised for further biochemical and ultrastructural analyses. </p> Results: AZT- or d4T-only caused significant mitochondrial dysfunction and mitochondrial ultrastructural damage compared to controls, while either naringin or vitamin E reversed indices of mitochondrial dysfunction evidenced by significantly reduced mitochondrial malondialdehyde (MDA) and blood lactate concentrations, increased liver manganese superoxide dismutase (MnSOD) activity and upregulate expression of mitochondrial-encoded subunit of electron transport chain (ETC) complex IV protein compared to AZT- or d4T-only treated rats. Furthermore, naringin or vitamin E, respectively, ameliorated mitochondrial damage observed in AZT- or d4T-only treated rats. Naringin ameliorated oxidative stress and NRTI-induced mitochondrial damage and might, therefore, be beneficial in managing toxicities and complications arising from NRTI use.

Coexistence of BRAF V600E and TERT Promoter Mutations in Low-grade Serous Carcinoma of Ovary Recurring as Carcinosarcoma in a Lymph Node: Report of a Case.

PubMed

Tavallaee, Mahkam; Steiner, David F; Zehnder, James L; Folkins, Ann K; Karam, Amer K

2018-04-03

Low-grade serous carcinomas only rarely coexist with or progress to high-grade tumors. We present a case of low-grade serous carcinoma with transformation to carcinosarcoma on recurrence in the lymph node. Identical BRAF V600E and telomerase reverse transcriptase promoter mutations were identified in both the original and recurrent tumor. Given that telomerase reverse transcriptase promotor mutations are thought to play a role in progression of other tumor types, the function of telomerase reverse transcriptase mutations in BRAF mutated low-grade serous carcinoma deserves investigation.

Naringin Reverses Hepatocyte Apoptosis and Oxidative Stress Associated with HIV-1 Nucleotide Reverse Transcriptase Inhibitors-Induced Metabolic Complications

PubMed Central

Adebiyi, Oluwafeyisetan O.; Adebiyi, Olubunmi A.; Owira, Peter M. O.

2015-01-01

Nucleoside Reverse Transcriptase Inhibitors (NRTIs) have not only improved therapeutic outcomes in the treatment of HIV infection but have also led to an increase in associated metabolic complications of NRTIs. Naringin’s effects in mitigating NRTI-induced complications were investigated in this study. Wistar rats, randomly allotted into seven groups (n = 7) were orally treated daily for 56 days with 100 mg/kg zidovudine (AZT) (groups I, II III), 50 mg/kg stavudine (d4T) (groups IV, V, VI) and 3 mL/kg of distilled water (group VII). Additionally, rats in groups II and V were similarly treated with 50 mg/kg naringin, while groups III and VI were treated with 45 mg/kg vitamin E. AZT or d4T treatment significantly reduced body weight and plasma high density lipoprotein concentrations but increased liver weights, plasma triglycerides and total cholesterol compared to controls, respectively. Furthermore, AZT or d4T treatment significantly increased oxidative stress, adiposity index and expression of Bax protein, but reduced Bcl-2 protein expression compared to controls, respectively. However, either naringin or vitamin E significantly mitigated AZT- or d4T-induced weight loss, dyslipidemia, oxidative stress and hepatocyte apoptosis compared to AZT- or d4T-only treated rats. Our results suggest that naringin reverses metabolic complications associated with NRTIs by ameliorating oxidative stress and apoptosis. This implies that naringin supplements could mitigate lipodystrophy and dyslipidemia associated with NRTI therapy. PMID:26690471

Elevated Human telomerase reverse transcriptase gene expression in blood cells associated with chronic and arsenic exposure in Inner Mongolia, China

EPA Science Inventory

BACKGROUND: Arsenic exposure is associated with human cancer. Telomerase containing the catalytic subunit, human telomerase reverse transcriptase (hTERT), can extend telomeres of chromosomes, delay senescence and promoting cell proliferation leading to tumorigenesis. OBJECTIVE:...

Synthesis of the highly selective p38 MAPK inhibitor UR-13756 for possible therapeutic use in Werner syndrome.

PubMed

Bagley, Mark C; Davis, Terence; Rokicki, Michal J; Widdowson, Caroline S; Kipling, David

2010-02-01

UR-13756 is a potent and selective p38 mitogen-activated protein kinase (MAPK) inhibitor, reported to have good bioavailability and pharmacokinetic properties and, thus, is of potential use in the treatment of accelerated aging in Werner syndrome. Irradiation of 2-chloroacrylonitrile and methylhydrazine in ethanol at 100 °C gives 1-methyl-3-aminopyrazole, which reacts with 4-fluorobenzaldehyde and a ketone, obtained by Claisen condensation of 4-picoline, in a Hantzsch-type 3-component hereocyclocondensation, to give the pyrazolopyridine UR-13756. UR-13756 shows p38 MAPK inhibitory activity in human telomerase reverse transcriptase-immortalized HCA2 dermal fibroblasts, with an IC(50) of 80 nm, as shown by ELISA, is 100% efficacious for up to 24 h at 1.0 μm and displays excellent kinase selectivity over the related stress-activated c-Jun kinases. In addition, UR-13756 is an effective p38 inhibitor at 1.0 μm in Werner syndrome cells, as shown by immunoblot. The convergent synthesis of UR-13756 is realized using microwave dielectric heating and provides a highly selective inhibitor that shows excellent selectivity for p38 MAPK over c-Jun N-terminal kinase.

Prevalence in the USA of rilpivirine resistance-associated mutations in clinical samples and effects on phenotypic susceptibility to rilpivirine and etravirine.

PubMed

Picchio, Gaston R; Rimsky, Laurence T; Van Eygen, Veerle; Haddad, Mojgan; Napolitano, Laura A; Vingerhoets, Johan

2014-01-01

The prevalence of rilpivirine resistance-associated mutations (RAMs) in the USA, and their effect on phenotypic susceptibility to rilpivirine and etravirine, was evaluated in clinical samples from HIV-1-infected patients. In total, 15,991 samples submitted to Monogram Biosciences (South San Francisco, CA, USA) for routine resistance testing between January 2010 and June 2011 were assessed for the presence of known rilpivirine RAMs K101E/P, E138A/G/K/Q/R, V179L, Y181C/I/V, Y188L, H221Y, F227C and M230I/L; non-nucleoside reverse transcriptase inhibitor (NNRTI) RAMs K103N, L100I and L100I+K103N; and the nucleoside reverse transcriptase inhibitor (NRTI) RAMs M184I/V and their combinations with rilpivirine RAMs. Phenotypic susceptibility (PhenoSenseGT(®) assay; Monogram Biosciences) was evaluated, with reduced susceptibility defined as fold change (FC) in 50% inhibitory concentration (IC50)>2.0 for rilpivirine and FC>2.9 for etravirine. Of the 15,991 samples, 17% harboured ≥1 rilpivirine RAMs. The prevalence of most rilpivirine RAMs and combinations of NNRTI RAMs of interest was low (≤3%), except for Y181C (7%). Rilpivirine RAMs were often associated with reduced rilpivirine phenotypic susceptibility. Median FC values >2.0 were observed for clinical isolates with rilpivirine RAMs K101P, E138Q/R, Y181C/I/V, Y188L or M230L, and for the combination of E138K with M184I/V, and K101E with M184I. Most rilpivirine FC values >2.0 were associated with etravirine FC values >2.9 for individual rilpivirine RAMs and those combined with M184I/V. There was no relationship between the presence of K103N and rilpivirine FC. However, the L100I+K103N combination (without rilpivirine RAMs), at <2% prevalence, was associated with a rilpivirine FC>2.0. Based on 15,991 US clinical samples from HIV-1-infected patients, the frequency of most known rilpivirine RAMs apart from Y181C was low.

Soaping the NMDA receptor: Various types of detergents influence differently [(3)H]MK-801 binding to rat brain membranes.

PubMed

Berger, Michael L

2016-01-01

Membranes prepared from rat brain were treated with increasing concentrations of cationic, neutral, anionic and zwitterionic surfactants. Potent inactivation of [(3)H]MK-801 binding to NMDA receptors (NRs) was provided by the cation cetyl pyridinium (IC50 25 μM) and the neutral digitonin (IC50 37 μM). A 2 h incubation of rat brain membranes at 24°C with 100 μM of the neutral Triton X-100 resulted in about 50% reversible inhibition (without inactivation). Reversible inhibition was also effected by the anion deoxycholate (IC50 700 μM), and by the zwitterions N-lauryl sulfobetaine (12-SB(±), 400 μM) and CHAPS (1.5 mM), with inactivation at higher concentrations. Keeping the NR cation channel in the closed state significantly protected against inactivation by cations and by 12-SB(±), but not by the other detergents. Inactivation depended differentially on the amount of the membranes, on the duration of the treatment, and on the temperature. Varying the amount of membranes by a factor 8 yielded for cetyl trimethylammonium (16-NMe3(+)) IC50s of inactivation from 10 to 80 μM, while for deoxycholate the IC50 of inactivation was 1.2 mM for all tissue quantities. Some compounds inactivated within a few min (16-NMe3(+), digitonin, CHAPS), while inactivation by others took at least half an hour (Triton X-100, deoxycholate, 12-SB(±)). These last 3 ones also exhibited the steepest temperature dependence. Knowledge about the influence of various parameters is helpful in selecting appropriate conditions allowing the treatment of brain membranes with amphiphiles without risking irreversible inactivation. Copyright © 2015 Elsevier B.V. All rights reserved.

Characterization of the cloned human intermediate-conductance Ca2+-activated K+ channel.

PubMed

Jensen, B S; Strobaek, D; Christophersen, P; Jorgensen, T D; Hansen, C; Silahtaroglu, A; Olesen, S P; Ahring, P K

1998-09-01

The human intermediate-conductance, Ca2+-activated K+ channel (hIK) was identified by searching the expressed sequence tag database. hIK was found to be identical to two recently cloned K+ channels, hSK4 and hIK1. RNA dot blot analysis showed a widespread tissue expression, with the highest levels in salivary gland, placenta, trachea, and lung. With use of fluorescent in situ hybridization and radiation hybrid mapping, hIK mapped to chromosome 19q13.2 in the same region as the disease Diamond-Blackfan anemia. Stable expression of hIK in HEK-293 cells revealed single Ca2+-activated K+ channels exhibiting weak inward rectification (30 and 11 pS at -100 and +100 mV, respectively). Whole cell recordings showed a noninactivating, inwardly rectifying K+ conductance. Ionic selectivity estimated from bi-ionic reversal potentials gave the permeability (PK/PX) sequence K+ = Rb+ (1.0) > Cs+ (10.4) > Na+, Li+, N-methyl-D-glucamine (>51). NH+4 blocked the channel completely. hIK was blocked by the classical inhibitors of the Gardos channel charybdotoxin (IC50 28 nM) and clotrimazole (IC50 153 nM) as well as by nitrendipine (IC50 27 nM), Stichodactyla toxin (IC50 291 nM), margatoxin (IC50 459 nM), miconazole (IC50 785 nM), econazole (IC50 2.4 microM), and cetiedil (IC50 79 microM). Finally, 1-ethyl-2-benzimidazolinone, an opener of the T84 cell IK channel, activated hIK with an EC50 of 74 microM.

Synthesis and evaluation of "AZT-HEPT", "AZT-pyridinone", and "ddC-HEPT" conjugates as inhibitors of HIV reverse transcriptase.

PubMed

Pontikis, R; Dollé, V; Guillaumel, J; Dechaux, E; Note, R; Nguyen, C H; Legraverend, M; Bisagni, E; Aubertin, A M; Grierson, D S; Monneret, C

2000-05-18

To test the concept that HIV reverse transcriptase could be effectively inhibited by "mixed site inhibitors", a series of seven conjugates containing both a nucleoside analogue component (AZT 1, ddC 2) and a nonnucleoside type inhibitor (HEPT analogue 12, pyridinone 27) were synthesized and evaluated for their ability to block HIV replication. The (N-3 and C-5)AZT-HEPT conjugates 15, 22, and 23 displayed 2-5 microM anti-HIV activity, but they had no effect on the replication of HIV-2 or the HIV-1 strain with the Y181C mutation. The (C-5)AZT-pyridinone conjugates 34-37 were found to be inactive. In marked contrast, the ddC-HEPT molecule 26 displayed the same potency (EC(50) = 0.45 microM) against HIV-1 (wild type and the Y181C nevirapine-resistant strain) and HIV-2 in cell culture. No synergistic effect was observed for these bis-substrate inhibitors, suggesting that the two individual inhibitor components in these molecules do not bind simultaneously in their respective sites. Interestingly, however, the results indicate that the AZT-HEPT conjugates and the ddC-HEPT derivative 26 inhibit reverse transcriptase (RT) in an opposite manner. One explanation for this difference is that the former compounds interact preferentially with the hydrophobic pocket in RT, whereas 26 (after supposed triphosphorylation) inhibits RT through binding in the catalytic site.

Reverse transcriptase activity and particles of retroviral density in cultured canine lymphosarcoma supernatants.

PubMed Central

Tomley, F. M.; Armstrong, S. J.; Mahy, B. W.; Owen, L. N.

1983-01-01

Lymphoid tissue from 43 cases of canine lymphosarcoma and from 40 clinically normal dogs have been examined for markers of retrovirus infection. From 69-76% of culture supernatants from lymphosarcomas were shown to contain particles of retroviral density and to possess poly rC-oligo dG templated polymerase (reverse transcriptase) activity compared with 17-24% of culture supernatants from normal canine lymphoid cells. In 6 culture supernatants from cases of lymphosarcoma, high molecular weight 60-70S RNA was detected and shown to be found in association with this particulate reverse transcriptase activity. No such RNA was detected in 6 culture supernatants from normal canine lymphoid cells. PMID:6186265

Use of propidium monoazide in reverse transcriptase PCR to distinguish between infectious and noninfectious enteric viruses in water samples

EPA Science Inventory

Human enteric viruses can be present in untreated and inadequately treated drinking water. Molecular methods, such as the reverse transcriptase PCR (RT-PCR), can detect viral genomes in a few hours, but they cannot distinguish between infectious and noninfectious viruses. Since o...

Interaction of aurintricarboxylic acid (ATA) with four nucleic acid binding proteins DNase I, RNase A, reverse transcriptase and Taq polymerase

NASA Astrophysics Data System (ADS)

Ghosh, Utpal; Giri, Kalyan; Bhattacharyya, Nitai P.

2009-12-01

In the investigation of interaction of aurintricarboxylic acid (ATA) with four biologically important proteins we observed inhibition of enzymatic activity of DNase I, RNase A, M-MLV reverse transcriptase and Taq polymerase by ATA in vitro assay. As the telomerase reverse transcriptase (TERT) is the main catalytic subunit of telomerase holoenzyme, we also monitored effect of ATA on telomerase activity in vivo and observed dose-dependent inhibition of telomerase activity in Chinese hamster V79 cells treated with ATA. Direct association of ATA with DNase I ( Kd = 9.019 μM)), RNase A ( Kd = 2.33 μM) reverse transcriptase ( Kd = 0.255 μM) and Taq polymerase ( Kd = 81.97 μM) was further shown by tryptophan fluorescence quenching studies. Such association altered the three-dimensional conformation of DNase I, RNase A and Taq polymerase as detected by circular dichroism. We propose ATA inhibits enzymatic activity of the four proteins through interfering with DNA or RNA binding to the respective proteins either competitively or allosterically, i.e. by perturbing three-dimensional structure of enzymes.

Selection and characterization of a mutant of feline immunodeficiency virus resistant to 2',3'-dideoxycytidine.

PubMed Central

Medlin, H K; Zhu, Y Q; Remington, K M; Phillips, T R; North, T W

1996-01-01

We have selected and plaque purified a mutant of feline immunodeficiency virus (FIV) that is resistant to 2',3'-dideoxycytidine (ddC). This mutant was selected in cultured cells in the continuous presence of 25 microM ddC. The mutant, designated DCR-5c, was fourfold resistant to ddC, threefold resistant to 2',3'-dideoxyinosine, and more than fourfold resistant to phosphonoformic acid. DCR-5c displayed little or no resistance to (-)-beta-2',3'-dideoxy-3'-thiacytidine, 3'-azido-3'-deoxythymidine, or 9-(2-phosphonylmethoxyethyl) adenine. Reverse transcriptase purified from DCR-5c was less susceptible to inhibition by ddCTP, phosphonoformic acid, ddATP, or azido-dTTP than the wild-type FIV reverse transcriptase. Sequence analysis of DCR-5c revealed a single base change (G to C at nucleotide 2342) in the reverse transcriptase-encoding region of FIV. This mutation results in substitution of His for Asp at codon 3 of FIV reverse transcriptase. The role of this mutation in ddC resistance was confirmed by site-directed mutagenesis. PMID:8849258

Synergy against drug-resistant HIV-1 with the microbicide antiretrovirals, dapivirine and tenofovir, in combination.

PubMed

Schader, Susan M; Colby-Germinario, Susan P; Schachter, Jordana R; Xu, Hongtao; Wainberg, Mark A

2011-08-24

To evaluate the candidate antiretroviral microbicide compounds, dapivirine (DAP) and tenofovir (TFV), alone and in combination against the transmission of wild-type and nonnucleoside reverse transcriptase inhibitor (NNRTI)-resistant HIV-1 from different subtypes. We determined single-drug efficacy of the RTIs, DAP and TFV, against subtype B and non-B wild-type and NNRTI-resistant HIV-1 in vitro. To assess breadth of activity, compounds were tested alone and in combination against wild-type and NNRTI-resistant subtype C primary HIV-1 isolates and complimentary clonal HIV-1 from subtypes B, C and CRF02_AG to control for viral variation. Early infection was quantified by counting light units emitted from TZM-bl cells less than 48-h postinfection. Combination ratios were based on drug inhibitory concentrations (IC(50)s) and combined effects were determined by calculating combination indices. Both candidate microbicide antiretrovirals demonstrated potent anti-NNRTI-resistant HIV-1 activity in vitro, albeit the combination protected better than the single-drug treatments. Of particular interest, the DAP with TFV combination exhibited synergy (50% combination index, CI(50) = 0.567) against subtype C NNRTI-resistant HIV-1, whereas additivity (CI(50) = 0.987) was observed against the wild-type counterpart from the same patient. The effect was not compounded by the presence of subdominant viral fractions, as experiments using complimentary clonal subtype C wild-type (CI(50) = 0.968) and NNRTI-resistant (CI(50) = 0.672) HIV-1, in lieu of the patient quasispecies, gave similar results. This study supports the notion that antiretroviral drug combinations may retain antiviral activity against some drug-resistant HIV-1 despite subtype classification and quasispecies diversity.

Efficacy and durability of nevirapine in antiretroviral drug näive patients.

PubMed

Lange, Joep M A

2003-09-01

Nevirapine is a non-nucleoside reverse transcriptase inhibitor (NNRTI) that was first reported in the scientific literature in 1990. Varying doses of nevirapine (NVP) and a number of regimens containing this NNRTI have been studied in antiretroviral (ARV) näive patients. Four key studies have compared the efficacy and safety of triple drug regimens containing NVP in ARV näive, HIV-1 infected patients. The INCAS study was the first demonstration of how to use NVP in an effective and durable manner: as a component of a triple drug regimen. The COMBINE Study was a comparison of protease inhibitor (PI)-based and NVP-based triple regimens. The Atlantic Study is comparing the safety and efficacy of three triple drug regimens in ARV näive patients. In this study, treatment consists of a divergent drug regimen (PI and nucleoside reverse transcriptase inhibitors, NRTIs) targeting both HIV-1 protease and reverse transcriptase or a convergent regimen targeting reverse transcriptase alone (three NRTIs or two NRTIs plus a NNRTI). A clinical endpoint study (BI 1090) compared the efficacy and durability of multi-drug regimens in ARV näive patients with high baseline plasma HIV-1 RNA levels (pVLs) and low peripheral blood CD4+ lymphocyte counts. Data from these studies confirm that triple regimens containing NVP suppressed viral replication for up to one year, even when the ARV näive patients had low CD4+ cell counts at baseline. Nevirapine-containing regimens suppressed pVLs to < 50 copies/ mL in approximately 50% of patients in the studies discussed (Intent to Treat analyses). Data from 96 weeks of follow up in the Atlantic Study demonstrates that the regimens containing didanosine and stavudine plus indinavir or NVP were significantly more successful in suppressing pVLs to < 50 copies/mL during this period than a regimen composed of these NRTIs and lamivudine (p < or = 0.001). As with other ARV drugs, NVP should always be used as part of a fully suppressive ARV regimen. When used in this way, it is an effective ARV drug, which contributes to durable virological and immunological responses in approximately half of all treated patients. Nevirapine-containing regimens are effective in patients with advanced HIV-1 infection, i.e., low CD4+ cell counts. Data will soon be available from the 2NN Study that compares the efficacy and safety of four different regimens using NVP once daily, NVP twice daily, efavirenz once daily or a combination of NVP and efavirenz. All four arms of the study include a backbone of stavudine and lamivudine.

Potent selective monoamine oxidase B inhibition by maackiain, a pterocarpan from the roots of Sophora flavescens.

PubMed

Lee, Hyun Woo; Ryu, Hyung Won; Kang, Myung-Gyun; Park, Daeui; Oh, Sei-Ryang; Kim, Hoon

2016-10-01

Monoamine oxidase (MAO) catalyzes the oxidation of monoamines and its two isoforms, MAO-A and MAO-B, break down neurotransmitter amines. Of the compounds isolated from the roots of Sophora flavescens, (-)-maackiain (4), a pterocarpan, was found to potently and selectively inhibit human MAO-B, with an IC50 of 0.68μM, and to have a selectivity index of 126.2 for MAO-B. As compared with other herbal natural products, the IC50 value of 4 for MAO-B is one of the lowest reported to date. Genistein (1) highly, effectively and non-selectively inhibited MAO-A and MAO-B with IC50 values of 3.9μM and 4.1μM, respectively. (-)-4-Hydroxy-3-methoxy-8,9-methylenedioxypterocarpan (2) effectively and non-selectively inhibited MAO-A and MAO-B with IC50 values of 20.3μM and 10.3μM, respectively. In addition, compound 4 reversibly and competitively inhibited MAO-B with a Ki value of 0.054μM. Molecular docking simulation revealed that the binding affinity of 4 for MAO-B (-26.6kcal/mol) was greater than its affinity for MAO-A (-8.3kcal/mol), which was in-line with our inhibitory activity findings. Furthermore, Cys172 of MAO-B was found to be a key residue for hydrogen bonding with compound 4. The findings of this study suggest compound 4 be viewed as a new potent, selective, and reversible MAO-B inhibitor, and that compounds 1 and 2 be considered useful lead compounds for the developments of nonselective and reversible MAO inhibitors for the treatment of disorders like Parkinson's disease, Alzheimer disease, and depression. Copyright © 2016 Elsevier Ltd. All rights reserved.

Development and evaluation of a culture-independent method for source determination of fecal wastes in surface and storm waters using reverse transcriptase-PCR detection of FRNA coliphage genogroup gene sequences.

EPA Science Inventory

A complete method, incorporating recently improved reverse transcriptase-PCR primer/probe assays and including controls for determining interferences to phage recoveries from water sample concentrates and for detecting interferences to their analysis, was developed for the direct...

Novel Structure of Ty3 Reverse Transcriptase | Center for Cancer Research

Cancer.gov

Retrotransposons are mobile genetic elements that self amplify via a single-stranded RNA intermediate, which is converted to double-stranded DNA by an encoded reverse transcriptase (RT) with both DNA polymerase (pol) and ribonuclease H (RNase) activities. Categorized by whether they contain flanking long terminal repeat (LTR) sequences, retrotransposons play a critical role in

Development and evaluation of a culture-independent method for source determination of fecal wastes in surface and storm waters using reverse transcriptase-PCR detection of FRNA coliphage genogroup gene sequences

EPA Science Inventory

A complete method, incorporating recently improved reverse transcriptase-PCR primer/probe assays and including controls for determining interferences to phage recoveries from water sample concentrates and for detecting interferences to their analysis, was developed for the direct...

Structure of HIV-1 nonnucleoside reverse transcriptase inhibitors derivatives of N-benzyl-benzimidazole with different substituents in position 4

NASA Astrophysics Data System (ADS)

Ziółkowska, Natasza E.; Michejda, Christopher J.; Bujacz, Grzegorz D.

2010-01-01

The constant development of new drugs against HIV-1 is necessary due to global expansion of AIDS and HIV-1 drug resistance. Nonnucleoside reverse transcriptase inhibitors of HIV-1 (NNRTIs) are potentially effective and nontoxic drugs in AIDS therapy. The crystal structures of six nonnucleoside inhibitors of HIV-1 reverse transcriptase (RT) derivatives of N-benzyl-benzimidazole are reported here. The investigated compounds belong to the group of so called "butterfly like" inhibitors with characteristic two π-electron moieties with an angled orientation. The structural data show the influence of the substituents of the benzimidazole ring on the geometry of the molecule and correlation between the structure of the inhibitor and its biological activity.

Contrasting ex vivo efficacies of "reversed chloroquine" compounds in chloroquine-resistant Plasmodium falciparum and P. vivax isolates.

PubMed

Wirjanata, Grennady; Sebayang, Boni F; Chalfein, Ferryanto; Prayoga; Handayuni, Irene; Noviyanti, Rintis; Kenangalem, Enny; Poespoprodjo, Jeanne Rini; Burgess, Steven J; Peyton, David H; Price, Ric N; Marfurt, Jutta

2015-09-01

Chloroquine (CQ) has been the mainstay of malaria treatment for more than 60 years. However, the emergence and spread of CQ resistance now restrict its use to only a few areas where malaria is endemic. The aim of the present study was to investigate whether a novel combination of a CQ-like moiety and an imipramine-like pharmacophore can reverse CQ resistance ex vivo. Between March to October 2011 and January to September 2013, two "reversed chloroquine" (RCQ) compounds (PL69 and PL106) were tested against multidrug-resistant field isolates of Plasmodium falciparum (n = 41) and Plasmodium vivax (n = 45) in Papua, Indonesia, using a modified ex vivo schizont maturation assay. The RCQ compounds showed high efficacy against both CQ-resistant P. falciparum and P. vivax field isolates. For P. falciparum, the median 50% inhibitory concentrations (IC50s) were 23.2 nM for PL69 and 26.6 nM for PL106, compared to 79.4 nM for unmodified CQ (P < 0.001 and P = 0.036, respectively). The corresponding values for P. vivax were 19.0, 60.0, and 60.9 nM (P < 0.001 and P = 0.018, respectively). There was a significant correlation between IC50s of CQ and PL69 (Spearman's rank correlation coefficient [r s] = 0.727, P < 0.001) and PL106 (rs = 0.830, P < 0.001) in P. vivax but not in P. falciparum. Both RCQs were equally active against the ring and trophozoite stages of P. falciparum, but in P. vivax, PL69 and PL106 showed less potent activity against trophozoite stages (median IC50s, 130.2 and 172.5 nM) compared to ring stages (median IC50s, 17.6 and 91.3 nM). RCQ compounds have enhanced ex vivo activity against CQ-resistant clinical isolates of P. falciparum and P. vivax, suggesting the potential use of reversal agents in antimalarial drug development. Interspecies differences in RCQ compound activity may indicate differences in CQ pharmacokinetics between the two Plasmodium species. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Nelfinavir and non-nucleoside reverse transcriptase inhibitor-based salvage regimens in heavily HIV pretreated patients

PubMed Central

Baril, Jean-Guy; Lefebvre, Eric A; Lalonde, Richard G; Shafran, Stephen D; Conway, Brian

2003-01-01

OBJECTIVE: To assess the efficacy of nelfinavir mesylate (NFV) in combination with delavirdine mesylate (DLV) or efavirenz (EFV) and other antiretroviral agents following virological failure on other protease inhibitor (PI)-based regimens. DESIGN: Multicentre, retrospective chart review. METHODS: One hundred-one patients who were naive to both NFV and non-nucleoside reverse transcriptase inhibitors (NNRTIs) and who initiated NFV plus DLV or EFV-based salvage regimens were reviewed. Response to treatment was defined as a reduction in HIV ribonucleic acid (RNA) levels to unquantifiable levels (less than 50 copies/mL, less than 400 copies/mL, less than 500 copies/mL) on at least one occasion after the initiation of salvage therapy. Baseline correlates of response, including prior duration of HIV infection, prior number of regimens, viral load and CD4 cell counts were also evaluated. RESULTS: Patients had a mean duration of HIV infection of 10 years, a mean duration of prior therapy of four years, a median of four prior nucleoside reverse transcriptase inhibitors and a median of two prior PIs. At the time of review the mean duration of salvage therapy was 63.4 weeks. Virological suppression was achieved in 59 (58.4%) patients within a mean of eight weeks and maintained for a mean of 44.9 weeks (the mean follow-up was 78 weeks). Of the non-responders, 16 (38%) achieved a less than 1 log10 decrease in HIV RNA levels. Although there was no association between baseline correlates, response rate (75.7%) was significantly higher in patients with HIV RNA levels of 50,000 copies/mL or lower and CD4 counts greater than 200 cells/mm3. CONCLUSION: NFV/NNRTI-based highly active antiretroviral therapy regimens are an effective therapy in many patients who have experienced virological breakthroughs on at least one prior PI-based regimen. PMID:18159457

The group II intron maturase: a reverse transcriptase and splicing factor go hand in hand.

PubMed

Zhao, Chen; Pyle, Anna Marie

2017-12-01

The splicing of group II introns in vivo requires the assistance of a multifunctional intron encoded protein (IEP, or maturase). Each IEP is also a reverse-transcriptase enzyme that enables group II introns to behave as mobile genetic elements. During splicing or retro-transposition, each group II intron forms a tight, specific complex with its own encoded IEP, resulting in a highly reactive holoenzyme. This review focuses on the structural basis for IEP function, as revealed by recent crystal structures of an IEP reverse transcriptase domain and cryo-EM structures of an IEP-intron complex. These structures explain how the same IEP scaffold is utilized for intron recognition, splicing and reverse transcription, while providing a physical basis for understanding the evolutionary transformation of the IEP into the eukaryotic splicing factor Prp8. Copyright © 2017 Elsevier Ltd. All rights reserved.

Predicting human immunodeficiency virus inhibitors using multi-dimensional Bayesian network classifiers.

PubMed

Borchani, Hanen; Bielza, Concha; Toro, Carlos; Larrañaga, Pedro

2013-03-01

Our aim is to use multi-dimensional Bayesian network classifiers in order to predict the human immunodeficiency virus type 1 (HIV-1) reverse transcriptase and protease inhibitors given an input set of respective resistance mutations that an HIV patient carries. Multi-dimensional Bayesian network classifiers (MBCs) are probabilistic graphical models especially designed to solve multi-dimensional classification problems, where each input instance in the data set has to be assigned simultaneously to multiple output class variables that are not necessarily binary. In this paper, we introduce a new method, named MB-MBC, for learning MBCs from data by determining the Markov blanket around each class variable using the HITON algorithm. Our method is applied to both reverse transcriptase and protease data sets obtained from the Stanford HIV-1 database. Regarding the prediction of antiretroviral combination therapies, the experimental study shows promising results in terms of classification accuracy compared with state-of-the-art MBC learning algorithms. For reverse transcriptase inhibitors, we get 71% and 11% in mean and global accuracy, respectively; while for protease inhibitors, we get more than 84% and 31% in mean and global accuracy, respectively. In addition, the analysis of MBC graphical structures lets us gain insight into both known and novel interactions between reverse transcriptase and protease inhibitors and their respective resistance mutations. MB-MBC algorithm is a valuable tool to analyze the HIV-1 reverse transcriptase and protease inhibitors prediction problem and to discover interactions within and between these two classes of inhibitors. Copyright © 2012 Elsevier B.V. All rights reserved.

Telomerase reverse transcriptase (TERT) expression and role of vincristine sulfate in mouse model of malignancy related peritoneal ascites: an experimental metastatic condition.

PubMed

Chaklader, M; Das, P; Pereira, J A; Chatterjee, S; Basak, P; Law, A; Banerjee, T; Chauhan, S; Law, S

2011-06-01

To evaluate the efficacy of intraperitoneal vincristine administration into ascitic sarcoma-180 bearing mice as a model of human malignant ascites regarding various peritoneal/retroperitoneal sarcomatosis, and to evaluate the flowcytometric telomerase reverse transcriptase expression for the diagnostic and prognostic purposes. Present study included disease induction by intraperitoneal homologous ascitic sarcoma-180 transplantation followed by in vivo intraperitoneal drug administration to study mitotic index, flowcytometric cell cycle and telomerase reverse transcriptase expression pattern, erythrosin-B dye exclusion study for malignant cell viability assessment. Besides, in vitro malignant ascite culture in presence and absence of vincristine sulfate and survival study were also taken into consideration. Intraperitoneal vincristine administration (concentration 0.5 mg/kg body weight) significantly diminished the mitotic index in diseased subjects in comparison to untreated control subjects. Treated group of animals showed increased life span and median survival time. Cell viability assessment during the course of drug administration also revealed gradual depression on cell viability over time. Flowcytometric cell cycle analysis showed a good prognostic feature of chemotherapeutic administration schedule by representing high G2/M phase blocked cells along with reduced telomerase reverse transcriptase positive cells in treated animals. We conclude that long term administration of vincristine sulfate in small doses could be a good pharmacological intervention in case of malignant peritoneal ascites due to sarcomatosis as it indirectly reduced the level of telomerase reverse transcriptase expression in malignant cells by directly regulating cell cycle and simultaneously increased the life expectancy of the diseased subjects.

Nevirapine resistance mutation at codon 181 of the HIV-1 reverse transcriptase confers stavudine resistance by increasing nucleotide substrate discrimination and phosphorolytic activity.

PubMed

Blanca, Giuseppina; Baldanti, Fausto; Paolucci, Stefania; Skoblov, Alexander Yu; Victorova, Lyubov; Hübscher, Ulrich; Gerna, Giuseppe; Spadari, Silvio; Maga, Giovanni

2003-05-02

Recombinant HIV-1 reverse transcriptase (RT) carrying non-nucleoside inhibitors (NNRTIs) resistance mutation at codon 181 showed reduced incorporation and high efficiency of phosphorolytic removal of stavudine, a nucleoside RT inhibitor. These results reveal a new mechanism for cross-resistance between different classes of HIV-1 RT inhibitors.

Applicability of integrated cell culture reverse transcriptase quantitative PCR (ICC-RTqPCR) for the simultaneous detection of the four human enteric enterovirus species in disinfection studies

EPA Science Inventory

A newly developed integrated cell culture reverse transcriptase quantitative PCR (ICC-RTqPCR) method and its applicability in UV disinfection studies is described. This method utilizes a singular cell culture system coupled with four RTqPCR assays to detect infectious serotypes t...

Nonnucleoside reverse transcriptase inhibitor phenotypic hypersusceptibility can be demonstrated in different assays.

PubMed

Shulman, Nancy S; Delgado, Jamael; Bosch, Ronald J; Winters, Mark A; Johnston, Elizabeth; Shafer, Robert W; Katzenstein, David A; Merigan, Thomas C

2005-05-01

HIV-1 isolates harboring multiple nucleoside reverse transcriptase inhibitor (NRTI) resistance mutations are more susceptible ("hypersusceptible") to the nonnucleoside reverse transcriptase inhibitors (NNRTIs) than isolates lacking NRTI resistance mutations, but this has only been reported with a single-cycle replication phenotypic assay. In fact, there was a report that a commercial multicycle assay did not readily detect hypersusceptibility. To see whether NNRTI hypersusceptibility can be demonstrated in other types of phenotypic assays, including multicycle assays and enzyme inhibition assays. The susceptibility of HIV-1 clones derived from different patients in multicycle assays was tested in peripheral blood mononuclear cells (PBMCs) and in an established cell line. In addition, the reverse transcriptase (RT) of many of these clones was expressed and their susceptibility tested in an RT inhibition assay. Nevirapine and efavirenz susceptibilities were tested and compared with a control wild-type virus or RT. Hypersusceptibility to nevirapine and efavirenz was detected using each of the methods described above. R values correlating the other methods with single-cycle assay values were between 0.66 and 0.96. In addition to the high correlations, the different methods gave similar numeric results. NNRTI hypersusceptibility is readily seen in multicycle susceptibility assays and in enzyme inhibition assays.

KINETIC CHARACTERIZATION AND MOLECULAR DOCKING OF A NOVEL, POTENT, AND SELECTIVE SLOW-BINDING INHIBITOR OF HUMAN CATHEPSIN L

PubMed Central

Shah, Parag P.; Myers, Michael C.; Beavers, Mary Pat; Purvis, Jeremy E.; Jing, Huiyan; Grieser, Heather J.; Sharlow, Elizabeth R.; Napper, Andrew D.; Huryn, Donna M.; Cooperman, Barry S.; Smith, Amos B.; Diamond, Scott L.

2008-01-01

A novel small molecule thiocarbazate (PubChem SID 26681509), a potent inhibitor of human cathepsin L (EC 3.4.22.15) with an IC50 of 56 nM, was developed following a 57,821 compound screen of the NIH Molecular Libraries Small Molecule Repository. After a 4 hr preincubation with cathepsin L, this compound became even more potent, demonstrating an IC50 of 1.0 nM. The thiocarbazate was determined to be a slow-binding and slowly reversible competitive inhibitor. Through a transient kinetic analysis for single-step reversibility, inhibition rate constants were kon = 24,000 M-1s-1 and koff = 2.2 × 10-5 s-1 (Ki = 0.89 nM). Molecular docking studies were undertaken using the experimentally-derived X-ray crystal structure of papain/CLIK-148 (1cvz.pdb). These studies revealed critical hydrogen bonding patterns of the thiocarbazate with key active site residues in papain. The thiocarbazate displayed 7- to 151-fold greater selectivity toward cathepsin L than papain and cathepsins B, K, V, and S with no activity against cathepsin G. The inhibitor demonstrated a lack of toxicity in human aortic endothelial cells and zebrafish. Additionally, the thiocarbazate inhibited in vitro propagation of malaria parasite Plasmodium falciparum with an IC50 of 15.4 μM and inhibited Leishmania major with an IC50 of 12.5 μM. PMID:18403718

Reversal of in vitro cellular MRP1 and MRP2 mediated vincristine resistance by the flavonoid myricetin.

PubMed

van Zanden, Jelmer J; de Mul, Anika; Wortelboer, Heleen M; Usta, Mustafa; van Bladeren, Peter J; Rietjens, Ivonne M C M; Cnubben, Nicole H P

2005-06-01

In the present study, the effects of myricetin on either MRP1 or MRP2 mediated vincristine resistance in transfected MDCKII cells were examined. The results obtained show that myricetin can inhibit both MRP1 and MRP2 mediated vincristine efflux in a concentration dependent manner. The IC50 values for cellular vincristine transport inhibition by myricetin were 30.5+/-1.7 microM for MRP1 and 24.6+/-1.3 microM for MRP2 containing MDCKII cells. Cell proliferation analysis showed that the MDCKII control cells are very sensitive towards vincristine toxicity with an IC50 value of 1.1+/-0.1 microM. The MDCKII MRP1 and MRP2 cells are less sensitive towards vincristine toxicity with IC50 values of 33.1+/-1.9 and 22.2+/-1.4 microM, respectively. In both the MRP1 and MRP2 cells, exposure to 25 microM myricetin enhances the sensitivity of the cells towards vincristine toxicity to IC50 values of 7.6+/-0.5 and 5.8+/-0.5 microM, respectively. The increase of sensitivity represents a reversal of the resistance towards vincristine as a result of MRP1 and MRP2 inhibition. Thus, the present study demonstrates the ability of the flavonoid myricetin to modulate MRP1 and MRP2 mediated resistance to the anticancer drug vincristine in transfected cells, indicating that flavonoids might be a valuable adjunct to chemotherapy to block MRP mediated resistance.

Drug resistance mutations in HIV type 1 isolates from naive patients eligible for first line antiretroviral therapy in JJ Hospital, Mumbai, India.

PubMed

Deshpande, Alake; Karki, Surendra; Recordon-Pinson, Patricia; Fleury, Herve J

2011-12-01

More than 50 HIV-1-infected patients, naive of antiretroviral therapy (ART) but eligible for first line ART in JJ Hospital, Mumbai, India were investigated for surveillance drug resistance mutations (SDRMs); all but one virus belonged to subtype C; we could observe SDRMs to nonnucleoside reverse transcriptase inhibitors and protease inhibitors in 9.6% of the patients.

Oxadiazole-isopropylamides as Potent and Non-covalent Proteasome Inhibitors

PubMed Central

Ozcan, Sevil; Kazi, Aslamuzzaman; Marsilio, Frank; Fang, Bin; Guida, Wayne C.; Koomen, John; Lawrence, Harshani R.; Sebti, Saïd M.

2013-01-01

Screening of the 50,000 ChemBridge compound library led to the identification of the oxadiazole-isopropylamide 1 (PI-1833) which inhibited CT-L activity (IC50 0.60 μM) with little effects on the other 2 major proteasome proteolytic activities, T-L and PGPH-L. LC/MS-MS and dialysis show that 1 is a non-covalent and rapidly reversible CT-L inhibitor. Focused library synthesis provided 11ad (PI-1840) with CT-L activity (IC50 27 nM). Detailed SAR studies indicate that the amide moiety and the 2 phenyl rings are sensitive toward modifications. Hydrophobic residues, such as propyl or butyl, in the para-position (not ortho or meta) of the A-ring and a meta-pyridyl group as B-ring significantly improve activity. Compound 11ad (IC50 0.37 μM) is more potent than 1 (IC50 3.5 μM) at inhibiting CT-L activity in intact MDA-MB-468 human breast cancer cells and inhibiting their survival. The activity of 11ad warrants further pre-clinical investigation of this class as non-covalent proteasome inhibitors. PMID:23547706

Approved Antiviral Drugs over the Past 50 Years

PubMed Central

2016-01-01

SUMMARY Since the first antiviral drug, idoxuridine, was approved in 1963, 90 antiviral drugs categorized into 13 functional groups have been formally approved for the treatment of the following 9 human infectious diseases: (i) HIV infections (protease inhibitors, integrase inhibitors, entry inhibitors, nucleoside reverse transcriptase inhibitors, nonnucleoside reverse transcriptase inhibitors, and acyclic nucleoside phosphonate analogues), (ii) hepatitis B virus (HBV) infections (lamivudine, interferons, nucleoside analogues, and acyclic nucleoside phosphonate analogues), (iii) hepatitis C virus (HCV) infections (ribavirin, interferons, NS3/4A protease inhibitors, NS5A inhibitors, and NS5B polymerase inhibitors), (iv) herpesvirus infections (5-substituted 2′-deoxyuridine analogues, entry inhibitors, nucleoside analogues, pyrophosphate analogues, and acyclic guanosine analogues), (v) influenza virus infections (ribavirin, matrix 2 protein inhibitors, RNA polymerase inhibitors, and neuraminidase inhibitors), (vi) human cytomegalovirus infections (acyclic guanosine analogues, acyclic nucleoside phosphonate analogues, pyrophosphate analogues, and oligonucleotides), (vii) varicella-zoster virus infections (acyclic guanosine analogues, nucleoside analogues, 5-substituted 2′-deoxyuridine analogues, and antibodies), (viii) respiratory syncytial virus infections (ribavirin and antibodies), and (ix) external anogenital warts caused by human papillomavirus infections (imiquimod, sinecatechins, and podofilox). Here, we present for the first time a comprehensive overview of antiviral drugs approved over the past 50 years, shedding light on the development of effective antiviral treatments against current and emerging infectious diseases worldwide. PMID:27281742

4'-Ethynyl-2-fluoro-2'-deoxyadenosine, MK-8591: a novel HIV-1 reverse transcriptase translocation inhibitor.

PubMed

Markowitz, Martin; Sarafianos, Stefan G

2018-07-01

4'-Ethynyl-2-fluoro-2'-deoxyadenosine (EFdA) is a nucleoside reverse transcriptase inhibitor (NRTI) with a novel mechanism of action, unique structure, and amongst NRTIs, unparalleled anti-HIV-1 activity. We will summarize its structure and function, antiviral activity, resistance profile, and potential as an antiretroviral for use in the treatment and preexposure prophylaxis of HIV-1 infection. EFdA is active against wild-type (EC50 as low as 50 pmol/l) and most highly NRTI-resistant viruses. The active metabolite, EFdA-triphosphate, has been shown to have a prolonged intracellular half-life in human and rhesus (Rh) blood cells. As a result, single drug doses tested in simian immunodeficiency virus mac251-infected Rh macaques and HIV-1-infected individuals exhibited robust antiviral activity of 7-10 days duration. Preclinical studies of EFdA as preexposure prophylaxis in the Rh macaque/simian/human immunodeficiency virus low-dose intrarectal challenge model have shown complete protection when given in clinically relevant doses. EFdA is a novel antiretroviral with activity against both wild-type and NRTI-resistant viruses. As a result of the prolonged intracellular half-life of its active moiety, it is amenable to flexibility in dosing of at least daily to weekly and perhaps longer.

Phylogenetic analysis of HIV-1 reverse transcriptase sequences from 382 patients recruited in JJ Hospital of Mumbai, India, between 2002 and 2008.

PubMed

Deshpande, Alaka; Jauvin, Valerie; Pinson, Patricia; Jeannot, Anne Cecile; Fleury, Herve J

2009-06-01

Analysis of reverse transcriptase (RT) sequences of 382 HIV-1 isolates from untreated and treated patients recruited in JJ Hospital (Mumbai, India) between 2002 and 2008 shows that subtype C is largely predominant (98%) and that non-C sequences cluster with A1, B, CRF01_AE, and CRF06_cpx.

Thieno[3,2-b]pyrrole-5-carboxamides as New Reversible Inhibitors of Histone Lysine Demethylase KDM1A/LSD1. Part 1: High-Throughput Screening and Preliminary Exploration.

PubMed

Sartori, Luca; Mercurio, Ciro; Amigoni, Federica; Cappa, Anna; Fagá, Giovanni; Fattori, Raimondo; Legnaghi, Elena; Ciossani, Giuseppe; Mattevi, Andrea; Meroni, Giuseppe; Moretti, Loris; Cecatiello, Valentina; Pasqualato, Sebastiano; Romussi, Alessia; Thaler, Florian; Trifiró, Paolo; Villa, Manuela; Vultaggio, Stefania; Botrugno, Oronza A; Dessanti, Paola; Minucci, Saverio; Zagarrí, Elisa; Carettoni, Daniele; Iuzzolino, Lucia; Varasi, Mario; Vianello, Paola

2017-03-09

Lysine specific demethylase 1 KDM1A (LSD1) regulates histone methylation and it is increasingly recognized as a potential therapeutic target in oncology. We report on a high-throughput screening campaign performed on KDM1A/CoREST, using a time-resolved fluorescence resonance energy transfer (TR-FRET) technology, to identify reversible inhibitors. The screening led to 115 hits for which we determined biochemical IC 50 , thus identifying four chemical series. After data analysis, we have prioritized the chemical series of N-phenyl-4H-thieno[3, 2-b]pyrrole-5-carboxamide for which we obtained X-ray structures of the most potent hit (compound 19, IC 50 = 2.9 μM) in complex with the enzyme. Initial expansion of this chemical class, both modifying core structure and decorating benzamide moiety, was directed toward the definition of the moieties responsible for the interaction with the enzyme. Preliminary optimization led to compound 90, which inhibited the enzyme with a submicromolar IC 50 (0.162 μM), capable of inhibiting the target in cells.

Amarogentin Induces Apoptosis of Liver Cancer Cells via Upregulation of p53 and Downregulation of Human Telomerase Reverse Transcriptase in Mice.

PubMed

Huang, Chun; Li, Runqin; Zhang, Yinglin; Gong, Jianping

2017-10-01

Amarogentin has been reported to have a preventive effect on liver cancer via inducing cancer cell apoptosis. We attempted to elucidate the roles of p53-associated apoptosis pathways in the chemopreventive mechanism of amarogentin. The findings of this study will facilitate the development of a novel supplementary strategy for the treatment of liver cancer. The purity of amarogentin was assessed by high-performance liquid chromatography. The inhibitory ratios of the liver cell lines were determined using a Cell Counting Kit-8 following treatment with a gradient concentration of amarogentin. Cell apoptosis was detected by flow cytometry using annexin V-fluorescein isothiocyanate/propidium iodide kits. The gene and protein expression of p53-associated molecules, such as Akt, human telomerase reverse transcriptase, RelA, and p38, was detected by real-time quantitative polymerase chain reaction, Western blotting, and immunohistochemical staining in liver cancer cells and mouse tumor tissues after treatment with amarogentin. The inhibitory effect of amarogentin on cell proliferation was more obvious in liver cancer cells, and amarogentin was more likely to induce the apoptosis of liver cancer cells than that of normal liver cells. The gene and protein expression levels of Akt, RelA, and human telomerase reverse transcriptase were markedly higher in the control group than in the preventive group and treatment groups. Only the expression of human telomerase reverse transcriptase was downregulated, accompanied by the upregulation of p53. The results of our study suggest that amarogentin promotes apoptosis of liver cancer cells by the upregulation of p53 and downregulation of human telomerase reverse transcriptase and prevents the malignant transformation of these cells.

Amarogentin Induces Apoptosis of Liver Cancer Cells via Upregulation of p53 and Downregulation of Human Telomerase Reverse Transcriptase in Mice

PubMed Central

Li, Runqin; Zhang, Yinglin

2016-01-01

Background and Objective: Amarogentin has been reported to have a preventive effect on liver cancer via inducing cancer cell apoptosis. We attempted to elucidate the roles of p53-associated apoptosis pathways in the chemopreventive mechanism of amarogentin. The findings of this study will facilitate the development of a novel supplementary strategy for the treatment of liver cancer. Materials and Methods: The purity of amarogentin was assessed by high-performance liquid chromatography. The inhibitory ratios of the liver cell lines were determined using a Cell Counting Kit-8 following treatment with a gradient concentration of amarogentin. Cell apoptosis was detected by flow cytometry using annexin V-fluorescein isothiocyanate/propidium iodide kits. The gene and protein expression of p53-associated molecules, such as Akt, human telomerase reverse transcriptase, RelA, and p38, was detected by real-time quantitative polymerase chain reaction, Western blotting, and immunohistochemical staining in liver cancer cells and mouse tumor tissues after treatment with amarogentin. Results: The inhibitory effect of amarogentin on cell proliferation was more obvious in liver cancer cells, and amarogentin was more likely to induce the apoptosis of liver cancer cells than that of normal liver cells. The gene and protein expression levels of Akt, RelA, and human telomerase reverse transcriptase were markedly higher in the control group than in the preventive group and treatment groups. Only the expression of human telomerase reverse transcriptase was downregulated, accompanied by the upregulation of p53. Conclusion: The results of our study suggest that amarogentin promotes apoptosis of liver cancer cells by the upregulation of p53 and downregulation of human telomerase reverse transcriptase and prevents the malignant transformation of these cells. PMID:27402632

Inhibitory effect of aqueous dandelion extract on HIV-1 replication and reverse transcriptase activity

PubMed Central

2011-01-01

Background Acquired immunodeficiency syndrome (AIDS), which is caused by the human immunodeficiency virus (HIV), is an immunosuppressive disease that results in life-threatening opportunistic infections. The general problems in current therapy include the constant emergence of drug-resistant HIV strains, adverse side effects and the unavailability of treatments in developing countries. Natural products from herbs with the abilities to inhibit HIV-1 life cycle at different stages, have served as excellent sources of new anti-HIV-1 drugs. In this study, we aimed to investigate the anti-HIV-1 activity of aqueous dandelion extract. Methods The pseudotyped HIV-1 virus has been utilized to explore the anti-HIV-1 activity of dandelion, the level of HIV-1 replication was assessed by the percentage of GFP-positive cells. The inhibitory effect of the dandelion extract on reverse transcriptase activity was assessed by the reverse transcriptase assay kit. Results Compared to control values obtained from cells infected without treatment, the level of HIV-1 replication and reverse transcriptase activity were decreased in a dose-dependent manner. The data suggest that dandelion extract has a potent inhibitory activity against HIV-1 replication and reverse transcriptase activity. The identification of HIV-1 antiviral compounds from Taraxacum officinale should be pursued. Conclusions The dandelion extract showed strong activity against HIV-1 RT and inhibited both the HIV-1 vector and the hybrid-MoMuLV/MoMuSV retrovirus replication. These findings provide additional support for the potential therapeutic efficacy of Taraxacum officinale. Extracts from this plant may be regarded as another starting point for the development of an antiretroviral therapy with fewer side effects. PMID:22078030

Structural studies of series HIV-1 nonnucleoside reverse transcriptase inhibitors 1-(2,6-difluorobenzyl)-2-(2,6-difluorophenyl)-benzimidazoles with different 4-substituents

NASA Astrophysics Data System (ADS)

Ziółkowska, Natasza E.; Michejda, Christopher J.; Bujacz, Grzegorz D.

2010-03-01

Over the past 10 years, several anti-viral drugs have become available to fight the HIV infection. Antiretroviral treatment reduces the mortality of AIDS. Nonnucleoside inhibitors of HIV-1 reverse transcriptase are specific and potentially nontoxic drugs against AIDS. The crystal structures of five nonnucleoside inhibitors of HIV-1 reverse transcriptase are presented here. The structural parameters, especially those describing the angular orientation of the π-electron systems and influencing biological activity, were determined for all of the investigated inhibitors. The chemical character and orientation of the substituent at C4 position of the benzimidazole moiety substantially influences the anti-viral activity. The structural data of the investigated inhibitors is a good basis for modeling enzyme-inhibitor interactions for structure-assisted drug design.

Anti-HIV drugs: 25 compounds approved within 25 years after the discovery of HIV.

PubMed

De Clercq, Erik

2009-04-01

In 2008, 25 years after the human immunodeficiency virus (HIV) was discovered as the then tentative aetiological agent of acquired immune deficiency syndrome (AIDS), exactly 25 anti-HIV compounds have been formally approved for clinical use in the treatment of AIDS. These compounds fall into six categories: nucleoside reverse transcriptase inhibitors (NRTIs: zidovudine, didanosine, zalcitabine, stavudine, lamivudine, abacavir and emtricitabine); nucleotide reverse transcriptase inhibitors (NtRTIs: tenofovir); non-nucleoside reverse transcriptase inhibitors (NNRTIs: nevirapine, delavirdine, efavirenz and etravirine); protease inhibitors (PIs: saquinavir, ritonavir, indinavir, nelfinavir, amprenavir, lopinavir, atazanavir, fosamprenavir, tipranavir and darunavir); cell entry inhibitors [fusion inhibitors (FIs: enfuvirtide) and co-receptor inhibitors (CRIs: maraviroc)]; and integrase inhibitors (INIs: raltegravir). These compounds should be used in drug combination regimens to achieve the highest possible benefit, tolerability and compliance and to diminish the risk of resistance development.

Virtual screening studies on HIV-1 reverse transcriptase inhibitors to design potent leads.

PubMed

Vadivelan, S; Deeksha, T N; Arun, S; Machiraju, Pavan Kumar; Gundla, Rambabu; Sinha, Barij Nayan; Jagarlapudi, Sarma A R P

2011-03-01

The purpose of this study is to identify novel and potent inhibitors against HIV-1 reverse transcriptase (RT). The crystal structure of the most active ligand was converted into a feature-shaped query. This query was used to align molecules to generate statistically valid 3D-QSAR (r(2) = 0.873) and Pharmacophore models (HypoGen). The best HypoGen model consists of three Pharmacophore features (one hydrogen bond acceptor, one hydrophobic aliphatic and one ring aromatic) and further validated using known RT inhibitors. The designed novel inhibitors are further subjected to docking studies to reduce the number of false positives. We have identified and proposed some novel and potential lead molecules as reverse transcriptase inhibitors using analog and structure based studies. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Simultaneous Detection of Rift Valley Fever, Bluetongue, Rinderpest, and Peste des Petits Ruminants Viruses by a Single-Tube Multiplex Reverse Transcriptase-PCR Assay Using a Dual-Priming Oligonucleotide System▿

PubMed Central

Yeh, Jung-Yong; Lee, Ji-Hye; Seo, Hyun-Ji; Park, Jee-Yong; Moon, Jin-San; Cho, In-Soo; Choi, In-Soo; Park, Seung-Yong; Song, Chang-Seon; Lee, Joong-Bok

2011-01-01

The aim of this study was to develop a highly sensitive and specific one-step multiplex reverse transcriptase PCR assay for the simultaneous and differential detection of Rift Valley Fever virus (RVFV), bluetongue virus (BTV), rinderpest virus (RPV), and Peste des petits ruminants virus (PPRV). These viruses cause mucosal lesions in cattle, sheep, and goats, and they are difficult to differentiate from one another based solely on their clinical presentation in suspected disease cases. In this study, we developed a multiplex reverse transcriptase PCR to detect these viruses using a novel dual-priming oligonucleotide (DPO). The DPO contains two separate priming regions joined by a polydeoxyinosine linker, which blocks extension of nonspecifically primed templates and consistently allows high PCR specificity even under less-than-optimal PCR conditions. A total of 19 DPO primers were designed to detect and discriminate between RVFV, BTV, RPV, and PPRV by the generation of 205-, 440-, 115-, and 243-bp cDNA products, respectively. The multiplex reverse transcriptase PCR described here enables the early diagnosis of these four viruses and may also be useful as part of a testing regime for cattle, sheep, or goats exhibiting similar clinical signs, including mucosal lesions. PMID:21307219

Combination nucleoside/nucleotide reverse transcriptase inhibitors for treatment of HIV infection.

PubMed

Akanbi, Maxwell O; Scarsi, Kimberly K; Scarci, Kimberly; Taiwo, Babafemi; Murphy, Robert L

2012-01-01

The combination of two nucleoside/nucleotide reverse transcriptase inhibitors (N(t)RTIs) and a third agent from another antiretroviral class is currently recommended for initial antiretroviral therapy. In general, N(t)RTIs remain relevant in subsequent regimens. There are currently six nucleoside reverse transcriptase inhibitors and one nucleotide reverse transcriptase inhibitor drug entities available, and several formulations that include two or more N(t)RTIs in a fixed-dose combination. These entities have heterogeneous pharmacological and clinical properties. Accordingly, toxicity, pill burden, dosing frequency, potential drug-drug interaction, preexisting antiretroviral drug resistance and comorbid conditions should be considered when constructing a regimen. This approach is critical in order to optimize virologic efficacy and clinical outcomes. This article reviews N(t)RTI combinations used in the treatment of HIV-infected adults. The pharmacological properties of each N(t)RTI, and the clinical trials that have influenced treatment guidelines are discussed. It is likely that N(t)RTIs will continue to dominate the global landscape of HIV treatment and prevention, despite emerging interest in N(t)RTI-free combination therapy. Clinical domains where only few alternatives to N(t)RTIs exist include treatment of HIV/HBV coinfection and HIV-2. There is a need for novel N(t)RTIs with enhanced safety and resistance profiles compared with current N(t)RTIs.

Reverse Transcriptase-Containing Particles Induced in Rous Sarcoma Virus-Transformed Rat Cells by Arginine Deprivation

PubMed Central

Kotler, Moshe; Weinberg, Eynat; Haspel, Osnat; Becker, Yechiel

1972-01-01

Incubation of rat cells transformed by Rous sarcoma virus (RSV) in an arginine-deficient medium resulted in accumulation of particles in the culture medium. Such particles did not appear when the transformed rat cells were incubated in a complete medium nor in the medium of primary rat cells which were incubated either in arginine-deficient or complete media. The particles which were released from the arginine-deprived transformed rat cells resemble C-type particles in their properties. These particles band in sucrose gradients at a density of 1.16 g/ml and contain 35S ribonucleic acid (RNA) molecules and a reverse transcriptase activity. Analysis of the cytoplasm of transformed and primary rat cells, deprived and undeprived of arginine, revealed the presence of reverse transcriptase-containing particles which banded in sucrose gradients at a density of 1.14 g/ml. These particles differed from the particles released into the medium by the arginine-deprived RSV-transformed rat cells. The deoxyribonucleic acid (DNA) molecules synthesized in vitro by the reverse transcriptase present in the particles isolated from the medium of arginine-deprived cells hybridized to RSV RNA, whereas the DNA synthesized by the cell-bound enzyme had no homology to RSV RNA. PMID:4116137

Generation of thermostable Moloney murine leukemia virus reverse transcriptase variants using site saturation mutagenesis library and cell-free protein expression system.

PubMed

Katano, Yuta; Li, Tongyang; Baba, Misato; Nakamura, Miyo; Ito, Masaaki; Kojima, Kenji; Takita, Teisuke; Yasukawa, Kiyoshi

2017-12-01

We attempted to increase the thermostability of Moloney murine leukemia virus (MMLV) reverse transcriptase (RT). The eight-site saturation mutagenesis libraries corresponding to Ala70-Arg469 in the whole MMLV RT (Thr24-Leu671), in each of which 1 out of 50 amino acid residues was replaced with other amino acid residue, were constructed. Seven-hundred and sixty eight MMLV RT clones were expressed using a cell-free protein expression system, and their thermostabilities were assessed by the temperature of thermal treatment at which they retained cDNA synthesis activity. One clone D200C was selected as the most thermostable variant. The highest temperature of thermal treatment at which D200C exhibited cDNA synthesis activity was 57ºC, which was higher than for WT (53ºC). Our results suggest that a combination of site saturation mutagenesis library and cell-free protein expression system might be useful for generation of thermostable MMLV RT in a short period of time for expression and selection.

Simultaneous Administration of 2-Aminoethyl Diphenylborinate and Chloroquine Reverses Chloroquine Resistance in Malaria Parasites

PubMed Central

Mossaad, Ehab; Furuyama, Wakako; Enomoto, Masahiro; Kawai, Satoru; Mikoshiba, Katsuhiko

2015-01-01

A nearly complete reversal of chloroquine (CQ) resistance in the CQ-resistant Plasmodium falciparum K-1 strain, with a significant decrease in the mean ± standard deviation (SD) 50% inhibitory concentration (IC50) from 1,050 ± 95 nM to 14 ± 2 nM, was achieved in vitro by the simultaneous administration of 2-aminoethyl diphenylborinate (2-APB). The CQ resistance-reversing activity of 2-APB, which showed the same efficacy as verapamil, was also observed in an in vivo mouse infection model with the CQ-resistant Plasmodium chabaudi AS(30CQ) strain. PMID:25691631

Consensus criteria for sensitive detection of minimal neuroblastoma cells in bone marrow, blood and stem cell preparations by immunocytology and QRT-PCR: recommendations by the International Neuroblastoma Risk Group Task Force

PubMed Central

Beiske, K; Burchill, S A; Cheung, I Y; Hiyama, E; Seeger, R C; Cohn, S L; Pearson, A D J; Matthay, K K

2009-01-01

Disseminating disease is a predictive and prognostic indicator of poor outcome in children with neuroblastoma. Its accurate and sensitive assessment can facilitate optimal treatment decisions. The International Neuroblastoma Risk Group (INRG) Task Force has defined standardised methods for the determination of minimal disease (MD) by immunocytology (IC) and quantitative reverse transcriptase-polymerase chain reaction (QRT-PCR) using disialoganglioside GD2 and tyrosine hydroxylase mRNA respectively. The INRG standard operating procedures (SOPs) define methods for collecting, processing and evaluating bone marrow (BM), peripheral blood (PB) and peripheral blood stem cell harvest by IC and QRT-PCR. Sampling PB and BM is recommended at diagnosis, before and after myeloablative therapy and at the end of treatment. Peripheral blood stem cell products should be analysed at the time of harvest. Performing MD detection according to INRG SOPs will enable laboratories throughout the world to compare their results and thus facilitate quality-controlled multi-centre prospective trials to assess the clinical significance of MD and minimal residual disease in heterogeneous patient groups. PMID:19401690

The MONET trial: darunavir/ritonavir with or without nucleoside analogues, for patients with HIV RNA below 50 copies/ml.

PubMed

Arribas, Jose R; Horban, Andrzej; Gerstoft, Jan; Fätkenheuer, Gerdt; Nelson, Mark; Clumeck, Nathan; Pulido, Federico; Hill, Andrew; van Delft, Yvon; Stark, Thomas; Moecklinghoff, Christiane

2010-01-16

In virologically suppressed patients, darunavir-ritonavir (DRV/r) monotherapy could maintain virological suppression similarly to DRV/r and two nucleosides. Two hundred and fifty-six patients with HIV RNA less than 50 copies/ml for over 24 weeks on current antiretrovirals [non-nucleoside reverse transcriptase inhibitor (NNRTI)-based (43%), or protease inhibitor-based (57%)], switched to DRV/r 800/100 mg once daily, either as monotherapy (n = 127) or with two nucleoside reverse transcriptase inhibitors (NRTIs) (n = 129). Treatment failure was defined as two consecutive HIV RNA levels above 50 copies/ml (TLOVR) by week 48, or switches off study treatment. The trial had 80% power to show noninferiority for the monotherapy arm (delta = -12%). Patients were 81% male and 91% Caucasian, with mean age 44 years, and CD4 cell count of 574 cells/microl. In the primary efficacy analysis, HIV RNA less than 50 copies/ml by week 48 (per protocol) was 86.2 versus 87.8% in the monotherapy and triple therapy arms; by intent-to-treat switch equals failure, efficacy was 84.3 versus 85.3%; by a switch-included analysis, efficacy was 93.5 versus 95.1%: all three comparisons showed noninferior efficacy for DRV/r monotherapy. CD4 cell counts remained stable during the trial in both arms. One patient per arm showed at least one protease inhibitor mutation, and one patient in the triple therapy arm showed an NRTI mutation. Nine patients per arm discontinued randomized treatment for either adverse events or other reasons. No new or unexpected safety signals were detected. In this study for patients with HIV RNA less than 50 copies/ml on other antiretrovirals at baseline, switching to DRV/r monotherapy showed noninferior efficacy versus triple antiretroviral therapy.

Dynamics of drug resistance-associated mutations in HIV-1 DNA reverse transcriptase sequence during effective ART.

PubMed

Nouchi, A; Nguyen, T; Valantin, M A; Simon, A; Sayon, S; Agher, R; Calvez, V; Katlama, C; Marcelin, A G; Soulie, C

2018-05-29

To investigate the dynamics of HIV-1 variants archived in cells harbouring drug resistance-associated mutations (DRAMs) to lamivudine/emtricitabine, etravirine and rilpivirine in patients under effective ART free from selective pressure on these DRAMs, in order to assess the possibility of recycling molecules with resistance history. We studied 25 patients with at least one DRAM to lamivudine/emtricitabine, etravirine and/or rilpivirine identified on an RNA sequence in their history and with virological control for at least 5 years under a regimen excluding all drugs from the resistant class. Longitudinal ultra-deep sequencing (UDS) and Sanger sequencing of the reverse transcriptase region were performed on cell-associated HIV-1 DNA samples taken over the 5 years of follow-up. Viral variants harbouring the analysed DRAMs were no longer detected by UDS over the 5 years in 72% of patients, with viruses susceptible to the molecules of interest found after 5 years in 80% of patients with UDS and in 88% of patients with Sanger. Residual viraemia with <50 copies/mL was detected in 52% of patients. The median HIV DNA level remained stable (2.4 at baseline versus 2.1 log10 copies/106 cells 5 years later). These results show a clear trend towards clearance of archived DRAMs to reverse transcriptase inhibitors in cell-associated HIV-1 DNA after a long period of virological control, free from therapeutic selective pressure on these DRAMs, reflecting probable residual replication in some reservoirs of the fittest viruses and leading to persistent evolution of the archived HIV-1 DNA resistance profile.

A decade of HIV-1 drug resistance in the United States: trends and characteristics in a large protease/reverse transcriptase and co-receptor tropism database from 2003 to 2012.

PubMed

Paquet, Agnes C; Solberg, Owen D; Napolitano, Laura A; Volpe, Joseph M; Walworth, Charles; Whitcomb, Jeannette M; Petropoulos, Christos J; Haddad, Mojgan

2014-01-01

Drug resistance testing and co-receptor tropism determination are key components of the management of antiretroviral therapy for HIV-1-infected individuals. The purpose of this study was to examine trends of HIV-1 resistance and viral evolution in the past decade by surveying a large commercial patient testing database. Temporal trends of drug resistance, viral fitness and co-receptor usage among samples submitted for routine phenotypic and genotypic resistance testing to protease inhibitors (PIs), nucleoside reverse transcriptase inhibitors (NRTIs) and non-nucleoside reverse transcriptase inhibitors (NNRTIs), as well as for tropism determination were investigated. Within 62,397 resistant viruses reported from 2003 to 2012, we observed a decreasing trend in the prevalence of three-class resistance (from 25% to 9%) driven by decreased resistance to PIs (43% to 21%) and NRTIs (79% to 57%), while observing a slight increase in NNRTI resistance (68% to 75%). The prevalence of CXCR4-mediated entry among tropism testing samples (n=52,945) declined over time from 47% in 2007 to 40% in 2012. A higher proportion of CXCR4-tropic viruses was observed within samples with three-class resistance (50%) compared with the group with no resistance (36%). Decreased prevalence of three-class resistance and increased prevalence of one-class resistance was observed within samples reported between 2003 and 2012. The fraction of CXCR4-tropic viruses has decreased over time; however, CXCR4 usage was more prevalent among multi-class-resistant samples, which may be due to the more advanced disease stage of treatment-experienced patients. These trends have important implications for clinical practice and future drug discovery and development.

Novel Structure of Ty3 Reverse Transcriptase | Center for Cancer Research

Cancer.gov

Retrotransposons are mobile genetic elements that self amplify via a single-stranded RNA intermediate, which is converted to double-stranded DNA by an encoded reverse transcriptase (RT) with both DNA polymerase (pol) and ribonuclease H (RNase) activities. Categorized by whether they contain flanking long terminal repeat (LTR) sequences, retrotransposons play a critical role in the architecture of eukaryotic genomes and are the evolutionary origin of retroviruses, including human immunodeficiency virus (HIV).

The Role of eIF4E Activity in Breast Cancer

DTIC Science & Technology

2010-08-01

ORF, open reading frame; qPCR, quantitative PCR; RACE, rapid amplification of cDNA ends; RT, reverse transcriptase ; uORF, upstream ORF; UTR...were also performed using template lacking RT ( reverse transcriptase ): products were either undetectable or greatly reduced (>30000-fold less product...have previously shown that a 5’UTR expressed from the human AXIN2 gene contains a sixty nucleotide sequence that is predicted to form a stable stem

Crystal structures of HIV-1 nonnucleoside reverse transcriptase inhibitors: N-benzyl-4-methyl-benzimidazoles

NASA Astrophysics Data System (ADS)

Ziółkowska, Natasza E.; Michejda, Christopher J.; Bujacz, Grzegorz D.

2009-07-01

HIV-1 nonnucleoside reverse transcriptase inhibitors are potentially specific and effective drugs in AIDS therapy. The presence of two aromatic systems with an angled orientation in the molecule of the inhibitor is crucial for interactions with HIV-1 RT. The inhibitor drives like a wedge into the cluster of aromatic residues of RT HIV-1 and restrains the enzyme in a conformation that blocks the chemical step of nucleotide incorporation. Structural studies provide useful information for designing new, more active inhibitors. The crystal structures of four NNRTIs are presented here. The investigated compounds are derivatives of N-benzyl-4-methyl-benzimidazole with various aliphatic and aromatic substituents at carbon 2 positions and a 2,6-dihalogeno-substituted N-benzyl moiety. Structural data reported here show that the conformation of the investigated compounds is relatively rigid. Such feature is important for the nonnucleoside inhibitor binding to HIV-1 reverse transcriptase.

The history of antiretrovirals: key discoveries over the past 25 years.

PubMed

De Clercq, Erik

2009-09-01

Within 25 years after zidovudine (3'-azido-2',3'-dideoxythymidine, AZT) was first described as an inhibitor of HIV replication, 25 anti-HIV drugs have been formally approved for clinical use in the treatment of HIV infections: seven nucleoside reverse transcriptase inhibitors (NRTIs): zidovudine, didanosine, zalcitabine, stavudine, lamivudine, abacavir and emtricitabine; one nucleotide reverse transcriptase inhibitor (NtRTI): tenofovir [in its oral prodrug form: tenofovir disoproxil fumarate (TDF)]; four non-nucleoside reverse transcriptase inhibitors (NNRTIs): nevirapine, delavirdine, efavirenz and etravirine; ten protease inhibitors (PIs): saquinavir, ritonavir, indinavir, nelfinavir, amprenavir, lopinavir, atazanavir, fosamprenavir, tipranavir and darunavir; one fusion inhibitor (FI): enfuvirtide; one co-receptor inhibitor (CRI): maraviroc and one integrase inhibitor (INI): raltegravir. These compounds are used in various drug combination (some at fixed dose) regimens so as to achieve the highest possible benefit and tolerability, and to diminish the risk of virus-drug resistance development. (c) 2009 John Wiley & Sons, Ltd.

The public health approach to identify antiretroviral therapy failure: high-level nucleoside reverse transcriptase inhibitor resistance among Malawians failing first-line antiretroviral therapy

PubMed Central

Hosseinipour, Mina C.; van Oosterhout, Joep J.G.; Weigel, Ralf; Phiri, Sam; Kamwendo, Debbie; Parkin, Neil; Fiscus, Susan A.; Nelson, Julie A.E.; Eron, Joseph J.; Kumwenda, Johnstone

2010-01-01

Background Over 150 000 Malawians have started antiretroviral therapy (ART), in which first-line therapy is stavudine/lamivudine/nevirapine. We evaluated drug resistance patterns among patients failing first-line ART on the basis of clinical or immunological criteria in Lilongwe and Blantyre, Malawi. Methods Patients meeting the definition of ART failure (new or progressive stage 4 condition, CD4 cell count decline more than 30%, CD4 cell count less than that before treatment) from January 2006 to July 2007 were evaluated. Among those with HIV RNA of more than 1000 copies/ml, genotyping was performed. For complex genotype patterns, phenotyping was performed. Results Ninety-six confirmed ART failure patients were identified. Median (interquartile range) CD4 cell count, log10 HIV-1 RNA, and duration on ART were 68 cells/μl (23–174), 4.72 copies/ml (4.26–5.16), and 36.5 months (26.6–49.8), respectively. Ninety-three percent of samples had nonnucleoside reverse transcriptase inhibitor mutations, and 81% had the M184V mutation. The most frequent pattern included M184V and nonnucleoside reverse transcriptase inhibitor mutations along with at least one thymidine analog mutation (56%). Twenty-three percent of patients acquired the K70E or K65R mutations associated with tenofovir resistance; 17% of the patients had pan-nucleoside resistance that corresponded to K65R or K70E and additional resistance mutations, most commonly the 151 complex. Emergence of the K65R and K70E mutations was associated with CD4 cell count of less than 100 cells/μl (odds ratio 6.1) and inversely with the use of zidovudine (odds ratio 0.18). Phenotypic susceptibility data indicated that the nucleoside reverse transcriptase inhibitor backbone with the highest activity for subsequent therapy was zidovudine/lamivudine/tenofovir, followed by lamivudine/tenofovir, and then abacavir/didanosine. Conclusion When clinical and CD4 cell count criteria are used to monitor first-line ART failure, extensive nucleoside reverse transcriptase inhibitor and nonnucleoside reverse transcriptase inhibitor resistance emerges, with most patients having resistance profiles that markedly compromise the activity of second-line ART. PMID:19417582

Benzyloxynitrostyrene analogues - A novel class of selective and highly potent inhibitors of monoamine oxidase B.

PubMed

Van der Walt, Mietha M; Terre'Blanche, Gisella; Petzer, Jacobus P; Petzer, Anél

2017-01-05

This study examines a series of novel 3-benzyloxy-β-nitrostyrene analogues as a novel class of inhibitors of the monoamine oxidase (MAO) enzymes. MAO inhibitors are considered useful for the treatment of depression and Parkinson's disease, and have recently attracted attention as potential therapeutic agents for a range of disorders including Alzheimer's disease, prostate cancer and certain cardiomyopathies. This study shows that the 3-benzyloxy-β-nitrostyrene analogues are potent inhibitors of the MAO-B isoform with IC 50 values in the nanomolar range (39-565 nM). Significantly, effectiveness towards MAO-B inhibition seems to be governed by the introduction of a 4″-fluoro-substituent on the benzyloxy ring, with compound 2b exhibiting the highest degree of MAO-B inhibition potency (IC 50  = 0.039 μM) and selectivity (SI = 166) among the compounds investigated. Since some of the 3-benzyloxy-β-nitrostyrene analogues possess potencies that are comparable to that of the reversible inhibitor, safinamide (IC 50  = 0.080 μM), it may be concluded that this class may be promising leads for the development of reversible and selective MAO-B inhibitors, that may be useful for the management of Parkinson's disease. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

The Role of elF4E Activity in Breast Cancer

DTIC Science & Technology

2011-08-01

protein; ORF, open reading frame; qPCR, quantitative PCR; RACE, rapid amplification of cDNA ends; RT, reverse transcriptase ; uORF, upstream ORF; UTR...Reactions were also performed using template lacking RT ( reverse transcriptase ): products were either undetectable or greatly reduced (>30000-fold less...that a 5’UTR expressed from the human AXIN2 gene contains a sixty nucleotide sequence that is predicted to form a stable stem-loop structure6. This

Molecular docking and 3D-QSAR studies on triazolinone and pyridazinone, non-nucleoside inhibitor of HIV-1 reverse transcriptase.

PubMed

Sivan, Sree Kanth; Manga, Vijjulatha

2010-06-01

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) are allosteric inhibitors of the HIV-1 reverse transcriptase. Recently a series of Triazolinone and Pyridazinone were reported as potent inhibitors of HIV-1 wild type reverse transcriptase. In the present study, docking and 3D quantitative structure activity relationship (3D QSAR) studies involving comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were performed on 31 molecules. Ligands were built and minimized using Tripos force field and applying Gasteiger-Hückel charges. These ligands were docked into protein active site using GLIDE 4.0. The docked poses were analyzed; the best docked poses were selected and aligned. CoMFA and CoMSIA fields were calculated using SYBYL6.9. The molecules were divided into training set and test set, a PLS analysis was performed and QSAR models were generated. The model showed good statistical reliability which is evident from the r2 nv, q2 loo and r2 pred values. The CoMFA model provides the most significant correlation of steric and electrostatic fields with biological activities. The CoMSIA model provides a correlation of steric, electrostatic, acceptor and hydrophobic fields with biological activities. The information rendered by 3D QSAR model initiated us to optimize the lead and design new potential inhibitors.

The Reverse Transcriptase of the Tf1 Retrotransposon Has a Specific Novel Activity for Generating the RNA Self-Primer That Is Functional in cDNA Synthesis▿

PubMed Central

Hizi, Amnon

2008-01-01

The Tf1 retrotransposon of Schizosaccharomyces pombe represents a group of eukaryotic long terminal repeat (LTR) retroelements that, based on their sequences, were predicted to use an RNA self-primer for initiating reverse transcription while synthesizing the negative-sense DNA strand. This feature is substantially different from the one typical to retroviruses and other LTR retrotransposons that all exhibit a tRNA-dependent priming mechanism. Genetic studies have suggested that the self-primer of Tf1 can be generated by a cleavage between the 11th and 12th bases of the Tf1 RNA transcript. The in vitro data presented here show that recombinant Tf1 reverse transcriptase indeed introduces a nick at the end of a duplexed region at the 5′ end of Tf1 genomic RNA, substantiating the prediction that this enzyme is responsible for generating this RNA self-primer. The 3′ end of the primer, generated in this manner, can then be extended upon the addition of deoxynucleoside triphosphates by the DNA polymerase activity of the same enzyme, synthesizing the negative-sense DNA strand. This functional primer must have been generated by the RNase H activity of Tf1 reverse transcriptase, since a mutant enzyme lacking this activity has lost its ability to generate the self-primer. It was also found here that the reverse transcriptases of human immunodeficiency virus type 1 and of murine leukemia virus do not exhibit this specific cleavage activity. In all, it is likely that the observed unique mechanism of self-priming in Tf1 represents an early advantageous form of initiating reverse transcription in LTR retroelements without involving cellular tRNAs. PMID:18753200

The reverse transcriptase of the Tf1 retrotransposon has a specific novel activity for generating the RNA self-primer that is functional in cDNA synthesis.

PubMed

Hizi, Amnon

2008-11-01

The Tf1 retrotransposon of Schizosaccharomyces pombe represents a group of eukaryotic long terminal repeat (LTR) retroelements that, based on their sequences, were predicted to use an RNA self-primer for initiating reverse transcription while synthesizing the negative-sense DNA strand. This feature is substantially different from the one typical to retroviruses and other LTR retrotransposons that all exhibit a tRNA-dependent priming mechanism. Genetic studies have suggested that the self-primer of Tf1 can be generated by a cleavage between the 11th and 12th bases of the Tf1 RNA transcript. The in vitro data presented here show that recombinant Tf1 reverse transcriptase indeed introduces a nick at the end of a duplexed region at the 5' end of Tf1 genomic RNA, substantiating the prediction that this enzyme is responsible for generating this RNA self-primer. The 3' end of the primer, generated in this manner, can then be extended upon the addition of deoxynucleoside triphosphates by the DNA polymerase activity of the same enzyme, synthesizing the negative-sense DNA strand. This functional primer must have been generated by the RNase H activity of Tf1 reverse transcriptase, since a mutant enzyme lacking this activity has lost its ability to generate the self-primer. It was also found here that the reverse transcriptases of human immunodeficiency virus type 1 and of murine leukemia virus do not exhibit this specific cleavage activity. In all, it is likely that the observed unique mechanism of self-priming in Tf1 represents an early advantageous form of initiating reverse transcription in LTR retroelements without involving cellular tRNAs.

The impact of HIV-1 reverse transcriptase polymorphisms on responses to first-line nonnucleoside reverse transcriptase inhibitor-based therapy in HIV-1-infected adults.

PubMed

Mackie, Nicola E; Dunn, David T; Dolling, David; Garvey, Lucy; Harrison, Linda; Fearnhill, Esther; Tilston, Peter; Sabin, Caroline; Geretti, Anna M

2013-09-10

HIV-1 genetic variability may influence antiretroviral therapy (ART) outcomes. The study aim was to determine the impact of polymorphisms in regions known to harbor major nonnucleoside reverse transcriptase inhibitor (NNRTI) resistance mutations (codons 90-108, 135-138, 179-190, 225-348) on virologic responses to first-line NNRTI-based ART. Reverse transcriptase sequences from ART-naive individuals who commenced efavirenz (EFV) or nevirapine (NVP) with at least two nucleos(t)ide reverse transcriptase inhibitors (NRTIs) without major drug resistance mutations were analyzed. The impact of polymorphisms on week 4 viral load decrease and time to virologic failure was measured over a median 97 weeks. Among 4528 patients, most were infected with HIV-1 subtype B (67%) and commenced EFV-based ART (84%). Overall, 2598 (57%) had at least one polymorphism, most frequently at codons 90, 98, 101, 103, 106, 135, 138, 179, and 238. Virologic failure rates were increased in patients with two (n = 597) or more than two (n = 72) polymorphisms [adjusted hazard ratio 1.43; 95% confidence interval (CI) 1.07-1.92; P = 0.016]. Polymorphisms associated with virologic failure occurred at codons 90 (mostly V90I), 98 (mostly A98S), and 103 (mostly K103R), with adjusted hazard ratios of 1.78 (1.15-2.73; P = 0.009), 1.55 (1.16-2.08; P = 0.003), and 1.75 (1.00-3.05: P = 0.049), respectively. Polymorphisms at codon 179, especially V179D/E/T, predicted reduced week 4 responses (P = 0.001) but not virologic failure. The occurrence of multiple polymorphisms, though uncommon, was associated with a small increase in the risk of NNRTI treatment failure; significant effects were seen with polymorphisms at codon 90, 98, and 103. The mechanisms underlying the slower suppression seen with V179D/E/T deserve further investigation.

Reversible Cysteine Protease Inhibitors Show Promise for a Chagas Disease Cure

PubMed Central

Beaulieu, Christian; Black, W. Cameron; Isabel, Elise; Vasquez-Camargo, Fabio; Nath-Chowdhury, Milli; Massé, Frédéric; Mellon, Christophe; Methot, Nathalie

2014-01-01

The cysteine protease cruzipain is essential for the viability, infectivity, and virulence of Trypanosoma cruzi, the causative agent of Chagas disease. Thus, inhibitors of cruzipain are considered promising anti-T. cruzi chemotherapeutic agents. Reversible cruzipain inhibitors containing a nitrile “warhead” were prepared and demonstrated 50% inhibitory concentrations (IC50s) as potent as 1 nM in baculovirus-generated cruzipain enzyme assays. In epimastigote and intracellular amastigote in vitro assays, the most potent compounds demonstrated antiparasitic behavior in the 5 to 10 μM IC50 range; however, trypomastigote production from the amastigote form was ∼90 to 95% inhibited at 2 μM. Two key compounds, Cz007 and Cz008, with IC50s of 1.1 and 1.8 nM, respectively, against the recombinant enzyme were tested in a murine model of acute T. cruzi infection, with oral dosing in chow for 28 days at doses from 3 to 50 mg/kg of body weight. At 3 mg/kg of Cz007 and 3 mg/kg of Cz008, the blood parasitemia areas under the concentration-time curves were 16% and 25% of the untreated group, respectively. At sacrifice, 24 days after immunosuppression with cyclophosphamide, parasite presence in blood, heart, and esophagus was evaluated. Based on negative quantitative PCR results in all three tissues, cure rates in surviving animals were 90% for Cz007 at 3 mg/kg, 78% for Cz008 at 3 mg/kg, and 71% for benznidazole, the control compound, at 50 mg/kg. PMID:24323474

Novel Codon Insert in HIV Type 1 Clade B Reverse Transcriptase Associated with Low-Level Viremia During Antiretroviral Therapy

PubMed Central

Gianella, Sara; Vazquez, Homero; Ignacio, Caroline; Zweig, Adam C.; Richman, Douglas D.; Smith, Davey M.

2014-01-01

Abstract We investigated the pol genotype in two phylogenetically and epidemiologically linked partners, who were both experiencing persistent low-level viremia during antiretroviral therapy. In one partner we identified a new residue insertion between codon 248 and 249 of the HIV-1 RNA reverse transcriptase (RT) coding region (HXB2 numbering). We then investigated the potential impact of identified mutations in RT and antiretroviral binding affinity using a novel computational approach. PMID:24020934

3-Coumaranone derivatives as inhibitors of monoamine oxidase.

PubMed

Van Dyk, Adriaan S; Petzer, Jacobus P; Petzer, Anél; Legoabe, Lesetja J

2015-01-01

The present study examines the monoamine oxidase (MAO) inhibitory properties of a series of 20 3-coumaranone [benzofuran-3(2H)-one] derivatives. The 3-coumaranone derivatives are structurally related to series of α-tetralone and 1-indanone derivatives, which have recently been shown to potently inhibit MAO, with selectivity for MAO-B (in preference to the MAO-A isoform). 3-Coumaranones are similarly found to selectively inhibit human MAO-B with half-maximal inhibitory concentration (IC50) values of 0.004-1.05 µM. Nine compounds exhibited IC50<0.05 µM for the inhibition of MAO-B. For the inhibition of human MAO-A, IC50 values ranged from 0.586 to >100 µM, with only one compound possessing an IC50<1 µM. For selected 3-coumaranone derivatives, it is established that MAO-A and MAO-B inhibition are reversible since dialysis of enzyme-inhibitor mixtures almost completely restores enzyme activity. On the basis of the selectivity profiles and potent action, it may be concluded that the 3-coumaranone derivatives are suitable leads for the development of selective MAO-B inhibitors as potential treatment for disorders such as Parkinson's disease and Alzheimer's disease.

3-Coumaranone derivatives as inhibitors of monoamine oxidase

PubMed Central

Van Dyk, Adriaan S; Petzer, Jacobus P; Petzer, Anél; Legoabe, Lesetja J

2015-01-01

The present study examines the monoamine oxidase (MAO) inhibitory properties of a series of 20 3-coumaranone [benzofuran-3(2H)-one] derivatives. The 3-coumaranone derivatives are structurally related to series of α-tetralone and 1-indanone derivatives, which have recently been shown to potently inhibit MAO, with selectivity for MAO-B (in preference to the MAO-A isoform). 3-Coumaranones are similarly found to selectively inhibit human MAO-B with half-maximal inhibitory concentration (IC50) values of 0.004–1.05 µM. Nine compounds exhibited IC50<0.05 µM for the inhibition of MAO-B. For the inhibition of human MAO-A, IC50 values ranged from 0.586 to >100 µM, with only one compound possessing an IC50<1 µM. For selected 3-coumaranone derivatives, it is established that MAO-A and MAO-B inhibition are reversible since dialysis of enzyme–inhibitor mixtures almost completely restores enzyme activity. On the basis of the selectivity profiles and potent action, it may be concluded that the 3-coumaranone derivatives are suitable leads for the development of selective MAO-B inhibitors as potential treatment for disorders such as Parkinson’s disease and Alzheimer’s disease. PMID:26491258

Biotechnological applications of mobile group II introns and their reverse transcriptases: gene targeting, RNA-seq, and non-coding RNA analysis.

PubMed

Enyeart, Peter J; Mohr, Georg; Ellington, Andrew D; Lambowitz, Alan M

2014-01-13

Mobile group II introns are bacterial retrotransposons that combine the activities of an autocatalytic intron RNA (a ribozyme) and an intron-encoded reverse transcriptase to insert site-specifically into DNA. They recognize DNA target sites largely by base pairing of sequences within the intron RNA and achieve high DNA target specificity by using the ribozyme active site to couple correct base pairing to RNA-catalyzed intron integration. Algorithms have been developed to program the DNA target site specificity of several mobile group II introns, allowing them to be made into 'targetrons.' Targetrons function for gene targeting in a wide variety of bacteria and typically integrate at efficiencies high enough to be screened easily by colony PCR, without the need for selectable markers. Targetrons have found wide application in microbiological research, enabling gene targeting and genetic engineering of bacteria that had been intractable to other methods. Recently, a thermostable targetron has been developed for use in bacterial thermophiles, and new methods have been developed for using targetrons to position recombinase recognition sites, enabling large-scale genome-editing operations, such as deletions, inversions, insertions, and 'cut-and-pastes' (that is, translocation of large DNA segments), in a wide range of bacteria at high efficiency. Using targetrons in eukaryotes presents challenges due to the difficulties of nuclear localization and sub-optimal magnesium concentrations, although supplementation with magnesium can increase integration efficiency, and directed evolution is being employed to overcome these barriers. Finally, spurred by new methods for expressing group II intron reverse transcriptases that yield large amounts of highly active protein, thermostable group II intron reverse transcriptases from bacterial thermophiles are being used as research tools for a variety of applications, including qRT-PCR and next-generation RNA sequencing (RNA-seq). The high processivity and fidelity of group II intron reverse transcriptases along with their novel template-switching activity, which can directly link RNA-seq adaptor sequences to cDNAs during reverse transcription, open new approaches for RNA-seq and the identification and profiling of non-coding RNAs, with potentially wide applications in research and biotechnology.

Reverse transcription polymerase chain reaction protocols for cloning small circular RNAs.

PubMed

Navarro, B; Daròs, J A; Flores, R

1998-07-01

A protocol is described for general application for cloning small circular RNAs which requires only minimal amounts of template (approximately 50 ng) of unknown sequence. Both cDNA strands are synthesized with a 26-mer primer whose six 3'-terminal positions are totally degenerate in two consecutive reactions catalyzed by reverse transcriptase and DNA polymerase, respectively. The cDNAs are then PCR-amplified, using a 20-mer primer with the non-degenerate sequence of the previous primer, cloned and sequenced. This information permits the synthesis of one or more pairs of specific and adjacent primers for obtaining full-length cDNA clones by a protocol which is also described.

Murine Leukemia Virus Reverse Transcriptase: Structural Comparison with HIV-1 Reverse Transcriptase

PubMed Central

Coté, Marie L.; Roth, Monica J.

2008-01-01

Recent X-ray crystal structure determinations of Moloney murine leukemia virus reverse transcriptase (MoMLV RT) have allowed for more accurate structure/function comparisons to HIV-1 RT than were formerly possible. Previous biochemical studies of MoMLV RT in conjunction with knowledge of sequence homologies to HIV-1 RT and overall fold similarities to RTs in general, provided a foundation upon which to build. In addition, numerous crystal structures of the MoMLV RT fingers/palm subdomain had also shed light on one of the critical functions of the enzyme, specifically polymerization. Now in the advent of new structural information, more intricate examination of MoMLV RT in its entirety can be realized, and thus the comparisons with HIV-1 RT may be more critically elucidated. Here, we will review the similarities and differences between MoMLV RT and HIV-1 RT via structural analysis, and propose working models for the MoMLV RT based upon that information. PMID:18294720

Validation of a real-time reverse transcriptase-PCR assay for the detection of H7 avian influenza virus

USGS Publications Warehouse

Pedersen, J.; Killian, M.L.; Hines, N.; Senne, D.; Panigrahy, B.; Ip, Hon S.; Spackman, Erica

2010-01-01

This report describes the validation of an avian influenza virus (AIV) H7 subtype-specific real-time reverse transcriptasePCR (rRT-PCR) assay developed at the Southeast Poultry Research Laboratory (SEPRL) for the detection of H7 AI in North and South American wild aquatic birds and poultry. The validation was a collaborative effort by the SEPRL and the National Veterinary Services Laboratories. The 2008 H7 rRT-PCR assay detects 101 50% embryo infectious doses per reaction, or 103104 copies of transcribed H7 RNA. Diagnostic sensitivity and specificity were estimated to be 97.5% and 82.4%, respectively; the assay was shown to be specific for H7 AI when tested with >270 wild birds and poultry viruses. Following validation, the 2008 H7 rRT-PCR procedure was adopted as an official U.S. Department of Agriculture procedure for the detection of H7 AIV. The 2008 H7 assay replaced the previously used (2002) assay, which does not detect H7 viruses currently circulating in wild birds in North and South America. ?? 2010 American Association of Avian Pathologists.

HIVprotI: an integrated web based platform for prediction and design of HIV proteins inhibitors.

PubMed

Qureshi, Abid; Rajput, Akanksha; Kaur, Gazaldeep; Kumar, Manoj

2018-03-09

A number of anti-retroviral drugs are being used for treating Human Immunodeficiency Virus (HIV) infection. Due to emergence of drug resistant strains, there is a constant quest to discover more effective anti-HIV compounds. In this endeavor, computational tools have proven useful in accelerating drug discovery. Although methods were published to design a class of compounds against a specific HIV protein, but an integrated web server for the same is lacking. Therefore, we have developed support vector machine based regression models using experimentally validated data from ChEMBL repository. Quantitative structure activity relationship based features were selected for predicting inhibition activity of a compound against HIV proteins namely protease (PR), reverse transcriptase (RT) and integrase (IN). The models presented a maximum Pearson correlation coefficient of 0.78, 0.76, 0.74 and 0.76, 0.68, 0.72 during tenfold cross-validation on IC 50 and percent inhibition datasets of PR, RT, IN respectively. These models performed equally well on the independent datasets. Chemical space mapping, applicability domain analyses and other statistical tests further support robustness of the predictive models. Currently, we have identified a number of chemical descriptors that are imperative in predicting the compound inhibition potential. HIVprotI platform ( http://bioinfo.imtech.res.in/manojk/hivproti ) would be useful in virtual screening of inhibitors as well as designing of new molecules against the important HIV proteins for therapeutics development.

The 'glial' glutamate transporter, EAAT2 (Glt-1) accounts for high affinity glutamate uptake into adult rodent nerve endings.

PubMed

Suchak, Sachin K; Baloyianni, Nicoletta V; Perkinton, Michael S; Williams, Robert J; Meldrum, Brian S; Rattray, Marcus

2003-02-01

The excitatory amino acid transporters (EAAT) removes neurotransmitters glutamate and aspartate from the synaptic cleft. Most CNS glutamate uptake is mediated by EAAT2 into glia, though nerve terminals show evidence for uptake, through an unknown transporter. Reverse-transcriptase PCR identified the expression of EAAT1, EAAT2, EAAT3 and EAAT4 mRNAs in primary cultures of mouse cortical or striatal neurones. We have used synaptosomes and glial plasmalemmal vesicles (GPV) from adult mouse and rat CNS to identify the nerve terminal transporter. Western blotting showed detectable levels of the transporters EAAT1 (GLAST) and EAAT2 (Glt-1) in both synaptosomes and GPVs. Uptake of [3H]D-aspartate or [3H]L-glutamate into these preparations revealed sodium-dependent uptake in GPV and synaptosomes which was inhibited by a range of EAAT blockers: dihydrokainate, serine-o-sulfate, l-trans-2,4-pyrrolidine dicarboxylate (PDC) (+/-)-threo-3-methylglutamate and (2S,4R )-4-methylglutamate. The IC50 values found for these compounds suggested functional expression of the 'glial, transporter, EAAT2 in nerve terminals. Additionally blockade of the majority EAAT2 uptake sites with 100 micro m dihydrokainate, failed to unmask any functional non-EAAT2 uptake sites. The data presented in this study indicate that EAAT2 is the predominant nerve terminal glutamate transporter in the adult rodent CNS.

Lack of in vitro-in vivo correlation for a UC781-releasing vaginal ring in macaques.

PubMed

McConville, Christopher; Smith, James M; McCoy, Clare F; Srinivasan, Priya; Mitchell, James; Holder, Angela; Otten, Ron A; Butera, Salvatore; Doncel, Gustavo F; Friend, David R; Malcolm, R Karl

2015-02-01

This study describes the preclinical development of a matrix-type silicone elastomer vaginal ring device designed to provide controlled release of UC781, a non-nucleoside reverse transcriptase inhibitor. Testing of both human- and macaque-sized rings in a sink condition in vitro release model demonstrated continuous UC781 release in quantities considered sufficient to maintain vaginal fluid concentrations at levels 82-860-fold higher than the in vitro IC50 (2.0 to 10.4 nM) and therefore potentially protect against mucosal transmission of HIV. The 100-mg UC781 rings were well tolerated in pig-tailed macaques, did not induce local inflammation as determined by cytokine analysis and maintained median concentrations in vaginal fluids of UC781 in the range of 0.27 to 5.18 mM during the course of the 28-day study. Analysis of residual UC781 content in rings after completion of both the in vitro release and macaque pharmacokinetic studies revealed that 57 and 5 mg of UC781 was released, respectively. The pharmacokinetic analysis of a 100-mg UC781 vaginal ring in pig-tailed macaques showed poor in vivo-in vitro correlation, attributed to the very poor solubility of UC781 in vaginal fluid and resulting in a dissolution-controlled drug release mechanism rather than the expected diffusion-controlled mechanism.

In vitro Inhibitory Effect of Gymnema sylvestre Extracts and Total Gymnemic Acids Fraction on Select Cytochrome P450 Activities in Rat Liver Microsomes.

PubMed

Vaghela, Madhuri; Iyer, Krishna; Pandita, Nancy

2018-04-01

Gymnema sylvestre R. Br. is a well-known Indian medicinal herb. Gymnemic acids are pentacyclic triterpenes saponins and active phytoconstituents of Gymnema sylvestre. The study aimed at evaluation of the in vitro rat liver cytochrome P450 (CYP) inhibition potential of extracts and total gymnemic acid (TA)-enriched fractions from G. sylvestre. Standardization of G. sylvestre [ethanolic (EL), hydroethanolic (HE), total acid of ethanolic (TAE), total acid of hydroethanolic (TAHE) and total acid of aqueous (TAAQ) extract] was done with respect to deacyl gymnemic acid (DAGA), using reverse phase-high performance liquid chromatography (RP-HPLC). Total triterpenoid content was determined by vanillin perchloric acid assay. Total triterpene content was found to be the highest in TAAQ (59.86 ± 0.005% w/w) and TAE (49.77 ± 0.009% w/w). TAAQ showed IC 50  ≤ 50 µg/ml for all selected CYP activities. Testosterone 6β-hydroxylation was strongly inhibited by TAE (IC 50 : 15.48 ± 2.13 µg/ml) and was moderately by TAAQ and EL with IC 50  ≥ 50 µg/ml. Flurbiprofen 4'-hydroxylation was subject to strong, weak and moderate inhibition by TAAQ (IC 50 : 34.67 ± 1.38 µg/ml), TAE (IC 50 : ≥ 50 µg/ml) and EL (IC 50 : > 50 µg/ml), respectively. Dextromethorphan O-demethylation was inhibited by TAHE and TAAQ. In vitro inhibition studies suggested that TA strongly inhibits activity of selected CYP. This inhibition may possibly be due to triterpenoids and gymnemic acids that have been reported to be present in it. Data also suggest a potential for possible in vivo herb-drug interactions involving G. sylvestre and other medications that are metabolized by the same CYP.

Corticosteroid-induced gene expression in allergen-challenged asthmatic subjects taking inhaled budesonide

PubMed Central

Kelly, MM; King, EM; Rider, CF; Gwozd, C; Holden, NS; Eddleston, J; Zuraw, B; Leigh, R; O'Byrne, PM; Newton, R

2012-01-01

BACKGROUND AND PURPOSE Inhaled corticosteroids (ICS) are the cornerstone of asthma pharmacotherapy and, acting via the glucocorticoid receptor (GR), reduce inflammatory gene expression. While this is often attributed to a direct inhibitory effect of the GR on inflammatory gene transcription, corticosteroids also induce the expression of anti-inflammatory genes in vitro. As there are no data to support this effect in asthmatic subjects taking ICS, we have assessed whether ICS induce anti-inflammatory gene expression in subjects with atopic asthma. EXPERIMENTAL APPROACH Bronchial biopsies from allergen-challenged atopic asthmatic subjects taking inhaled budesonide or placebo were subjected to gene expression analysis using real-time reverse transcriptase-PCR for the corticosteroid-inducible genes (official gene symbols with aliases in parentheses): TSC22D3 [glucocorticoid-induced leucine zipper (GILZ)], dual-specificity phosphatase-1 (MAPK phosphatase-1), both anti-inflammatory effectors, and FKBP5 [FK506-binding protein 51 (FKBP51)], a regulator of GR function. Cultured pulmonary epithelial and smooth muscle cells were also treated with corticosteroids before gene expression analysis. KEY RESULTS Compared with placebo, GILZ and FKBP51 mRNA expression was significantly elevated in budesonide-treated subjects. Budesonide also increased GILZ expression in human epithelial and smooth muscle cells in culture. Immunostaining of bronchial biopsies revealed GILZ expression in the airways epithelium and smooth muscle of asthmatic subjects. CONCLUSIONS AND IMPLICATIONS Expression of the corticosteroid-induced genes, GILZ and FKBP51, is up-regulated in the airways of allergen-challenged asthmatic subjects taking inhaled budesonide. Consequently, the biological effects of corticosteroid-induced genes should be considered when assessing the actions of ICS. Treatment modalities that increase or decrease GR-dependent transcription may correspondingly affect corticosteroid efficacy. PMID:21827450

Btk Inhibitor RN983 Delivered by Dry Powder Nose-only Aerosol Inhalation Inhibits Bronchoconstriction and Pulmonary Inflammation in the Ovalbumin Allergic Mouse Model of Asthma.

PubMed

Phillips, Jonathan E; Renteria, Lorena; Burns, Lisa; Harris, Paul; Peng, Ruoqi; Bauer, Carla M T; Laine, Dramane; Stevenson, Christopher S

2016-06-01

In allergen-induced asthma, activated mast cells start the lung inflammatory process with degranulation, cytokine synthesis, and mediator release. Bruton's tyrosine kinase (Btk) activity is required for the mast cell activation during IgE-mediated secretion. This study characterized a novel inhaled Btk inhibitor RN983 in vitro and in ovalbumin allergic mouse models of the early (EAR) and late (LAR) asthmatic response. RN983 potently, selectively, and reversibly inhibited the Btk enzyme. RN983 displayed functional activities in human cell-based assays in multiple cell types, inhibiting IgG production in B-cells with an IC50 of 2.5 ± 0.7 nM and PGD2 production from mast cells with an IC50 of 8.3 ± 1.1 nM. RN983 displayed similar functional activities in the allergic mouse model of asthma when delivered as a dry powder aerosol by nose-only inhalation. RN983 was less potent at inhibiting bronchoconstriction (IC50(RN983) = 59 μg/kg) than the β-agonist salbutamol (IC50(salbutamol) = 15 μg/kg) in the mouse model of the EAR. RN983 was more potent at inhibiting the antigen induced increase in pulmonary inflammation (IC50(RN983) = <3 μg/kg) than the inhaled corticosteroid budesonide (IC50(budesonide) = 27 μg/kg) in the mouse model of the LAR. Inhalation of aerosolized RN983 may be effective as a stand-alone asthma therapy or used in combination with inhaled steroids and β-agonists in severe asthmatics due to its potent inhibition of mast cell activation.

Btk Inhibitor RN983 Delivered by Dry Powder Nose-only Aerosol Inhalation Inhibits Bronchoconstriction and Pulmonary Inflammation in the Ovalbumin Allergic Mouse Model of Asthma

PubMed Central

Renteria, Lorena; Burns, Lisa; Harris, Paul; Peng, Ruoqi; Bauer, Carla M.T.; Laine, Dramane; Stevenson, Christopher S.

2016-01-01

Abstract Background: In allergen-induced asthma, activated mast cells start the lung inflammatory process with degranulation, cytokine synthesis, and mediator release. Bruton's tyrosine kinase (Btk) activity is required for the mast cell activation during IgE-mediated secretion. Methods: This study characterized a novel inhaled Btk inhibitor RN983 in vitro and in ovalbumin allergic mouse models of the early (EAR) and late (LAR) asthmatic response. Results: RN983 potently, selectively, and reversibly inhibited the Btk enzyme. RN983 displayed functional activities in human cell-based assays in multiple cell types, inhibiting IgG production in B-cells with an IC50 of 2.5 ± 0.7 nM and PGD2 production from mast cells with an IC50 of 8.3 ± 1.1 nM. RN983 displayed similar functional activities in the allergic mouse model of asthma when delivered as a dry powder aerosol by nose-only inhalation. RN983 was less potent at inhibiting bronchoconstriction (IC50(RN983) = 59 μg/kg) than the β-agonist salbutamol (IC50(salbutamol) = 15 μg/kg) in the mouse model of the EAR. RN983 was more potent at inhibiting the antigen induced increase in pulmonary inflammation (IC50(RN983) = <3 μg/kg) than the inhaled corticosteroid budesonide (IC50(budesonide) = 27 μg/kg) in the mouse model of the LAR. Conclusions: Inhalation of aerosolized RN983 may be effective as a stand-alone asthma therapy or used in combination with inhaled steroids and β-agonists in severe asthmatics due to its potent inhibition of mast cell activation. PMID:27111445

HuR interacts with human immunodeficiency virus type 1 reverse transcriptase, and modulates reverse transcription in infected cells

PubMed Central

Lemay, Julie; Maidou-Peindara, Priscilla; Bader, Thomas; Ennifar, Eric; Rain, Jean-Christophe; Benarous, Richard; Liu, Lang Xia

2008-01-01

Reverse transcription of the genetic material of human immunodeficiency virus type 1 (HIV-1) is a critical step in the replication cycle of this virus. This process, catalyzed by reverse transcriptase (RT), is well characterized at the biochemical level. However, in infected cells, reverse transcription occurs in a multiprotein complex – the reverse transcription complex (RTC) – consisting of viral genomic RNA associated with viral proteins (including RT) and, presumably, as yet uncharacterized cellular proteins. Very little is known about the cellular proteins interacting with the RTC, and with reverse transcriptase in particular. We report here that HIV-1 reverse transcription is affected by the levels of a nucleocytoplasmic shuttling protein – the RNA-binding protein HuR. A direct protein-protein interaction between RT and HuR was observed in a yeast two-hybrid screen and confirmed in vitro by homogenous time-resolved fluorescence (HTRF). We mapped the domain interacting with HuR to the RNAse H domain of RT, and the binding domain for RT to the C-terminus of HuR, partially overlapping the third RRM RNA-binding domain of HuR. HuR silencing with specific siRNAs greatly impaired early and late steps of reverse transcription, significantly inhibiting HIV-1 infection. Moreover, by mutagenesis and immunoprecipitation studies, we could not detect the binding of HuR to the viral RNA. These results suggest that HuR may be involved in and may modulate the reverse transcription reaction of HIV-1, by an as yet unknown mechanism involving a protein-protein interaction with HIV-1 RT. PMID:18544151

Reverse Transcriptase Activity in Mature Spermatozoa of Mouse

PubMed Central

Giordano, Roberto; Magnano, Anna Rosa; Zaccagnini, Germana; Pittoggi, Carmine; Moscufo, Nicola; Lorenzini, Rodolfo; Spadafora, Corrado

2000-01-01

We show here that a reverse transcriptase (RT) activity is present in murine epididymal spermatozoa. Sperm cells incubated with human poliovirus RNA can take up exogenous RNA molecules and internalize them in nuclei. Direct PCR amplification of DNA extracted from RNA-incubated spermatozoa indicate that poliovirus RNA is reverse-transcribed in cDNA fragments. PCR analysis of two-cell embryos shows that poliovirus RNA-challenged spermatozoa transfer retrotranscribed cDNA molecules into eggs during in vitro fertilization. Finally, RT molecules can be visualized on sperm nuclear scaffolds by immunogold electron microscopy. These results, therefore, reveal a novel metabolic function in spermatozoa, which may play a role during early embryonic development. PMID:10725323

Unconventional plasticity of HIV-1 reverse transcriptase: how inhibitors could open a connection "gate" between allosteric and catalytic sites.

PubMed

Bellucci, Luca; Angeli, Lucilla; Tafi, Andrea; Radi, Marco; Botta, Maurizio

2013-12-23

Targeted molecular dynamics (TMD) simulations allowed for identifying the chemical/structural features of the nucleotide-competitive HIV-1 inhibitor DAVP-1, which is responsible for the disruption of the T-shape motif between Try183 and Trp229 of the reverse transcriptase (RT). DAVP-1 promoted the opening of a connection "gate" between allosteric and catalytic sites of HIV-1 RT, thus explaining its peculiar mechanism of action and providing useful insights to develop novel nucleotide-competitive RT inhibitors.

In Vitro Evaluation of Nonnucleoside Reverse Transcriptase Inhibitors UC-781 and TMC120-R147681 as Human Immunodeficiency Virus Microbicides†

PubMed Central

Van Herrewege, Yven; Michiels, Jo; Van Roey, Jens; Fransen, Katrien; Kestens, Luc; Balzarini, Jan; Lewi, Paul; Vanham, Guido; Janssen, Paul

2004-01-01

The nonnucleoside reverse transcriptase inhibitors UC-781 and TMC120-R147681 (Dapivirine) effectively prevented human immunodeficiency virus (HIV) infection in cocultures of monocyte-derived dendritic cells and T cells, representing primary targets in sexual transmission. Both drugs had a favorable therapeutic index. A 24-h treatment with 1,000 nM UC-781 or 100 nM TMC120-R147681 prevented cell-free HIV infection, whereas 10-fold-higher concentrations blocked cell-associated HIV. PMID:14693562

Gamma-irradiated bacterial preparation having anti-tumor activity

DOEpatents

Vass, Arpad A.; Tyndall, Richard L.; Terzaghi-Howe, Peggy

1999-01-01

A bacterial preparation from Pseudomonas species isolated #15 ATCC 55638 that has been exposed to gamma radiation exhibits cytotoxicity that is specific for neoplastic carcinoma cells. A method for obtaining a bacterial preparation having antitumor activity consists of suspending a bacterial isolate in media and exposing the suspension to gamma radiation. A bacterial preparation of an aged culture of an amoeba-associated bacteria exhibits anti-reverse transcriptase activity. A method for obtaining a bacterial preparation having anti-reverse transcriptase activity from an amoeba-associated bacterial isolate grown to stationary phase is disclosed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petzer, Anél, E-mail: 12264954@nwu.ac.za; Harvey, Brian H.; Wegener, Gregers

Methylene blue (MB) has been shown to act at multiple cellular and molecular targets and as a result possesses diverse medical applications. Among these is a high potency reversible inhibition of monoamine oxidase A (MAO-A) that may, at least in part, underlie its adverse effects but also its psycho- and neuromodulatory actions. MB is metabolized to yield N-demethylated products of which azure B, the monodemethyl species, is the major metabolite. Similar to MB, azure B also displays a variety of biological activities and may therefore contribute to the pharmacological profile of MB. Based on these observations, the present study examinesmore » the interactions of azure B with recombinant human MAO-A and -B. The results show that azure B is a potent MAO-A inhibitor (IC{sub 50} = 11 nM), approximately 6-fold more potent than is MB (IC{sub 50} = 70 nM) under identical conditions. Measurements of the time-dependency of inhibition suggest that the interaction of azure B with MAO-A is reversible. Azure B also reversibly inhibits the MAO-B isozyme with an IC{sub 50} value of 968 nM. These results suggest that azure B may be a hitherto under recognized contributor to the pharmacology and toxicology of MB by blocking central and peripheral MAO-A activity and as such needs to be considered during its use in humans and animals. Highlights: ► Methylene blue (MB) is a known potent MAO-A inhibitor. ► Azure B, the major metabolite of MB, is more potent as a MAO-A inhibitor. ► Azure B may be a contributor to the CNS pharmacology and toxicology of MB.« less

Maraviroc, as a Switch Option, in HIV-1–infected Individuals With Stable, Well-controlled HIV Replication and R5-tropic Virus on Their First Nucleoside/Nucleotide Reverse Transcriptase Inhibitor Plus Ritonavir-boosted Protease Inhibitor Regimen: Week 48 Results of the Randomized, Multicenter MARCH Study

PubMed Central

Pett, Sarah Lilian; Amin, Janaki; Horban, Andrejz; Andrade-Villanueva, Jaime; Losso, Marcelo; Porteiro, Norma; Sierra Madero, Juan; Belloso, Waldo; Tu, Elise; Silk, David; Kelleher, Anthony; Harrigan, Richard; Clark, Andrew; Sugiura, Wataru; Wolff, Marcelo; Gill, John; Gatell, Jose; Fisher, Martin; Clarke, Amanda; Ruxrungtham, Kiat; Prazuck, Thierry; Kaiser, Rolf; Woolley, Ian; Arnaiz, Juan Alberto; Cooper, David; Rockstroh, Jürgen K.; Mallon, Patrick; Emery, Sean; Kelleher, Anthony; Merlin, Kate; Yeung, Julie; Fsadni, Bertha; Marks, Kat; Suzuki, Kazuo; Rismanto, Nick; Salomon, Horacio; Rubio, Andrea E.; Chibo, Doris; Birch, Chris; Harrigan, Richard; Swenson, Luke; Chan, Dennison; Berg, Thomas; Obermeier, Martin; Kaiser, Rolf; Schuelter, Eugen; Sierra Aragon, Saleta; Luebke, Nadine; Coughlan, Suzie; Dean, Jonathan; Sugiura, Wataru; Iwatani, Yasumasa; Reyes Teran, Gustavo; Avila, Santiago; Ruxrungtham, Kiat; Sirivichayakul, Sunee; Naphassanant, May; Ubolyam, Sasiwimol; Kaye, Steve; Land, Sally; Walker, Sarah; Haubrich, Richard; DeJesus, Edwin; Emery, Sean; Pett, Sarah L.; Tu, Elise; Silk, David; Berthon-Jones, Nisha; Amin, Janaki; Espinosa, Natalie; Courtney-Vega, Kymme; Absar, Noorul; Haskelberg, Hila; Robson, Rose; Donaldson, Anna; Losso, Marcelo; Belloso, Waldo; Guelman, Daniel; Gambardella, Luciana; Valdovinos, Mariana; Gatell, Jose; Arnaiz, Juan; Beleta, Helena; Ramos, Nuria; Targa, Marta; Rockstroh, Jurgen; Späth, Brigitta; Boesecke, Christoph; Engelhardt, Angelika; Fisher, Martin; Perry, Nicky; Clarke, Amanda; Gill, John; Beckthold, Brenda; Clark, Andrew; Drummond, Fraser; Lefevre, Eric; Corr, Sharon; Grant, Carol; Lupo, Sergio; Peroni, Luciana; Italiano, Hospital; Sanchez, Marisa; De Paz Sierra, Mariana; Mejia, Ramos; Losso, Marcelo; Viloria, Guillermo; Parlante, Angel; Bissio, Emiliano; Luchetti, Pablo; Warley, Eduardo; Vieni, Ines; Porteiro, Norma; Vilas, Cecilia; Zarate, Abel; Mayer, Gabriela; Elliot, Julian; Hagenauer, Michelle; Kelley, Mark; Rowling, Diane; Gibson, Abby; Latch, Ngaire; Tabrett, Chantal; Warzywoda, Elizabeth; Cooper, David; Pett, Sarah; MacRae, Karen; Sinclair, Brett; Sinn, Kate; Bloch, Mark; Franic, Teo; Vincent, Trina; Stewart, Natasha; Jayewardene, Avindra; Dwyer, Dominic; Kok, Jennifer; Assam, Delene; Taylor, Janette; King, Patricia; Orth, David; Youds, David; Sowden, David; Johnston, Colleen; Murray, Suzanne; Hehir, Jennifer; Wadham, Samantha; Donohue, William; Thompson, Jill; Garsia, Roger; Turnham, Geoffrey; Madden, Tracey; Woolley, Ian; Gillies, Ainsley; Bryant, Mellissa; Gill, John; Beckthold, Brenda; Walmsley, Sharon; Chan, Warmond; LeBlanc, Roger; Lanteigne, Francois; Mouawad, Rima; Rahal, Ines; Guber, Sergio; Ozturk, Sefika; Smith, Graham; Halpenny, Roberta; Reko, Tatjana; Robinette Hills, Jennifer; Wolff, Marcelo; Prazuck, Thierry; Laurent Hocqueloux, Francois; Wolfgang, Johann; Stephan, Christoph; Ebeling, Franziska; Rockstroh, Juergen; Boesecke, Christoph; Spath, Brigitta; Engelhardt, Angelika; Ole Jensen, Bjorn-Erik; Feind, Cecilie; Meyer-Olson, Dirk; Stoll, Matthias; Hoeper, Kirsten; Beider, Renata; Faetkenheur, Gerd; Thomas Baumgarten, Ellen; Baumgarten, Axel; Ingiliz, Patrick; Wienbreyer, Andreas; Behrendt, Daniela; Nienkarken, Tanja; Stein, Jessen; Jessen, Heiko; Zedlack, Carmen; Mallon, Paddy; Simelane, Sibongile; Assmann, Jennifer; Ghavami-Kia, Bijan; Sugiura, Wataru; Imahashi, Mayumi; Tanabe, Kazue; Yokomaku, Yoshiyuki; Imamura, Junji; Andrade-Villanueva, Jaime; Montes de Oca, Melva; Gonzalez, Lucero; Ponce, David; Mendoza, Andrea; Sierra-Madero, Juan; Sanchez Hernandez, Jesus Eduardo; Jaime Ruiz Ballesteros, Eduardo; del Moral Ponce, Sergio; Mosqueda, Luis; Lopez, Monica; Horban, Andrzej; Ignatowska, Anna; Bakowska, Elzbieta; Pulik, Piotr; Sanz-Moreno, Jose; Paredes, Roger; Puig, Jordi; Domingo, Pere; Gutierrez, Mar; Gatell, Jose; González-Cordón, Ana; Callau, Pili; Lopez Aldeguer, Jose; Cuellar Tovar, Sandra; Leal Noval, Manuel; Rivas, Inmaculada; Delgado-Fernandez, Marcial; Ramon Arribas, Jose; Miguel Castro, Juan; Ruxrungtham, Kiat; Avihingsanon, Anchalee; Maek-a-nantawat, Wirach; Intasan, Jintana; Charoenporn, Walairat; Cuprasitrut, Thidarat; Jaisomkom, Pachuen; Pruksakaew, Kanchana; Winston, Alan; Mullaney, Scott; Fisher, Martin; Clarke, Amanda; Barbour, Lisa; Perry, Nicky; Richardson, Celia; Fox, Julie; Murray, Tammy; Leen, Clifford; Morris, Shelia; Satyajit, Das; Sandhu, Rumun; Tucker, James

2016-01-01

Abstract Background. Alternative combination antiretroviral therapies in virologically suppressed human immunodeficiency virus (HIV)–infected patients experiencing side effects and/or at ongoing risk of important comorbidities from current therapy are needed. Maraviroc (MVC), a chemokine receptor 5 antagonist, is a potential alternative component of therapy in those with R5-tropic virus. Methods. The Maraviroc Switch Study is a randomized, multicenter, 96-week, open-label switch study in HIV type 1–infected adults with R5-tropic virus, virologically suppressed on a ritonavir-boosted protease inhibitor (PI/r) plus double nucleoside/nucleotide reverse transcriptase inhibitor (2 N(t)RTI) backbone. Participants were randomized 1:2:2 to current combination antiretroviral therapy (control), or replacing the protease inhibitor (MVC + 2 N(t)RTI arm) or the nucleoside reverse transcriptase inhibitor backbone (MVC + PI/r arm) with twice-daily MVC. The primary endpoint was the difference (switch minus control) in proportion with plasma viral load (VL) <200 copies/mL at 48 weeks. The switch arms were judged noninferior if the lower limit of the 95% confidence interval (CI) for the difference in the primary endpoint was < −12% in the intention-to-treat (ITT) population. Results. The ITT population comprised 395 participants (control, n = 82; MVC + 2 N(t)RTI, n = 156; MVC + PI/r, n = 157). Baseline characteristics were well matched. At week 48, noninferior rates of virological suppression were observed in those switching away from a PI/r (93.6% [95% CI, −9.0% to 2.2%] and 91.7% [95% CI, −9.6% to 3.8%] with VL <200 and <50 copies/mL, respectively) compared to the control arm (97.6% and 95.1% with VL <200 and <50 copies/mL, respectively). In contrast, MVC + PI/r did not meet noninferiority bounds and was significantly inferior (84.1% [95% CI, −19.8% to −5.8%] and 77.7% [95% CI, −24.9% to −8.4%] with VL <200 and <50 copies/mL, respectively) to the control arm in the ITT analysis. Conclusions. These data support MVC as a switch option for ritonavir-boosted PIs when partnered with a 2-N(t)RTI backbone, but not as part of N(t)RTI-sparing regimens comprising MVC with PI/r. Clinical Trials Registration. NCT01384682. PMID:27048747

Efficacy and safety of TMC278 in antiretroviral-naive HIV-1 patients: week 96 results of a phase IIb randomized trial.

PubMed

Pozniak, Anton L; Morales-Ramirez, Javier; Katabira, Elly; Steyn, Dewald; Lupo, Sergio H; Santoscoy, Mario; Grinsztejn, Beatriz; Ruxrungtham, Kiat; Rimsky, Laurence T; Vanveggel, Simon; Boven, Katia

2010-01-02

TMC278 is a next-generation nonnucleoside reverse transcriptase inhibitor highly active against wild-type and nonnucleoside reverse transcriptase inhibitor-resistant HIV-1 in vitro. The week 96 analysis of TMC278-C204, a large dose-ranging study of TMC278 in treatment-naive HIV-1-infected patients, is presented. Phase IIb randomized trial. Three hundred sixty-eight patients were randomized and treated with three blinded once-daily TMC278 doses 25, 75 or 150 mg, or an open-label, active control, efavirenz 600 mg once daily, all with two nucleoside reverse transcriptase inhibitors. The primary analysis was at week 48. No TMC278 dose-response relationship for efficacy and safety was observed. TMC278 demonstrated potent antiviral efficacy comparable with efavirenz over 48 weeks that was sustained to week 96 (76.9-80.0% and 71.4-76.3% of TMC278-treated patients with confirmed viral load <50 copies/ml, respectively; time-to-loss of virological-response algorithm). Median increases from baseline in CD4 cell count with TMC278 at week 96 (138.0-149.0 cells/microl) were higher than at week 48 (108.0-123.0 cells/microl). All TMC278 doses were well tolerated. The incidences of the most commonly reported grade 2-4 adverse events at least possibly related to study medication, including nausea, dizziness, abnormal dreams/nightmare, dyspepsia, asthenia, rash, somnolence and vertigo, were low and lower with TMC278 than with efavirenz. Incidences of serious adverse events, grade 3 or 4 adverse events and discontinuations due to adverse events were similar among groups. All TMC278 doses demonstrated potent and sustained efficacy comparable with efavirenz in treatment-naive patients over 96 weeks. TMC278 was well tolerated with lower incidences of neurological and psychiatric adverse events, rash and lower lipid elevations than those with efavirenz. TMC278 25 mg once daily was selected for further clinical development.

Clinical and virologic follow-up in perinatally HIV-1-infected children and adolescents in Madrid with triple-class antiretroviral drug-resistant viruses.

PubMed

Rojas Sánchez, P; de Mulder, M; Fernandez-Cooke, E; Prieto, L; Rojo, P; Jiménez de Ory, S; José Mellado, M; Navarro, M; Tomas Ramos, J; Holguín, Á

2015-06-01

Drug resistance mutations compromise the success of antiretroviral treatment in human immunodeficiency virus type 1 (HIV-1)-infected children. We report the virologic and clinical follow-up of the Madrid cohort of perinatally HIV-infected children and adolescents after the selection of triple-class drug-resistant mutations (TC-DRM). We identified patients from the cohort carrying HIV-1 variants with TC-DRM to nucleoside reverse transcriptase inhibitors, nonnucleoside reverse transcriptase inhibitors and protease inhibitors according to IAS-USA-2013. We recovered pol sequences or resistance profiles from 2000 to 2011 and clinical-immunologic-virologic data from the moment of TC-DRM detection until December 2013. Viruses harbouring TC-DRM were observed in 48 (9%) of the 534 children and adolescents from 2000 to 2011, rising to 24.4% among those 197 with resistance data. Among them, 95.8% were diagnosed before 2003, 91.7% were Spaniards, 89.6% carried HIV-1-subtype B and 75% received mono/dual therapy as first regimen. The most common TC-DRM present in ≥50% of them were D67NME, T215FVY, M41L and K103N (retrotranscriptase) and L90M (protease). The susceptibility to darunavir, tipranavir, etravirine and rilpivirine was 67.7%, 43.7%, 33.3% and 33.3%, respectively, and all reported high resistance to didanosine, abacavir and nelfinavir. Despite the presence of HIV-1 resistance mutations to the three main antiretroviral families in our paediatric cohort, some drugs maintained their susceptibility, mainly the new protease inhibitors (tipranavir and darunavir) and nonnucleoside reverse transcriptase inhibitors (etravirine and rilpivirine). These data will help to improve the clinical management of HIV-infected children with triple resistance in Spain. Copyright © 2015 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Characteristics of a group of nonnucleoside reverse transcriptase inhibitors with structural diversity and potent anti-human immunodeficiency virus activity.

PubMed

Yang, S S; Fliakas-Boltz, V; Bader, J P; Buckheit, R W

1995-10-01

Current thrust in controlling the Acquired Immune Deficiency Syndrome (AIDS) focuses on antiviral drug development targeting the infection and replication of the human immunodeficiency virus (HIV), the causative agent of AIDS. To date, treatment of AIDS has relied on nucleoside reverse transcriptase inhibitors such as AZT, ddI, and ddC, which eventually become ineffective upon the emergence of resistant mutants bearing specific nucleotide substitutions. The Anti-AIDS Drug Screening Program of the NCI conducts and coordinates a high-capacity semi-robotic in vitro screening of synthetic or natural compounds submitted by academic, research and pharmaceutical institutions world-wide. About 10,000 synthetic compounds are screened annually for anti-HIV activity. Confirmed active agents are subjected to in-depth studies on range and mechanism of action. Emerging from this intense screening activity were a number of potentially promising categories of nonnucleoside reverse transcriptase inhibitors (NNRTI) with structural diversity but strong and reproducible anti-HIV activity. Over 2500 active compounds were evaluated for their inhibitory activity against a panel of both laboratory and clinical virus isolates in the appropriate established cell line or fresh human peripheral blood leukocyte and macrophage preparations. Out of these, 40 agents could be placed structurally in nine categories with an additional 16 unique compounds that share the characteristics of NNRTI. These NNRTIs were shown to inhibit reverse transcriptase enzymatically using homopolymeric or ribosomal RNA as templates. NNRTIs demonstrated similarity in their inhibitory pattern against the HIV-1 laboratory strains IIIB and RF, and an AZT-resistant strain; all were inactive against HIV-2. These compounds were further tested against NNRTI-resistant HIV-1 isolates. NNRTI-resistant HIV-1 isolates were selected and characterized with respect to the change(s) in the viral reverse transcriptase nucleotide sequence. Also, differential cross-resistance or sensitivity patterns to NNRTIs were studied in detail among NNRTI-resistant mutants. When tested in combination with AZT, all of the NNRTI's uniformly exhibited synergistic inhibition of HIV-1, suggesting that combination antiviral therapy of NNRTIs with AZT may be therapeutically promising for AIDS treatment.

Exploration of a Library of 3,4-(Methylenedioxy)aniline-Derived Semicarbazones as Dual Inhibitors of Monoamine Oxidase and Acetylcholinesterase: Design, Synthesis, and Evaluation.

PubMed

Tripathi, Rati K P; Rai, Gopal K; Ayyannan, Senthil R

2016-06-06

A library of 3,4-(methylenedioxy)aniline-derived semicarbazones was designed, synthesized, and evaluated as monoamine oxidase (MAO) and acetylcholinesterase (AChE) inhibitors for the treatment of neurodegenerative diseases. Most of the new compounds selectively inhibited MAO-B and AChE, with IC50 values in the micro- or nanomolar ranges. Compound 16, 1-(2,6-dichlorobenzylidene)-4-(benzo[1,3]dioxol-5-yl)semicarbazide presented a balanced multifunctional profile of MAO-A (IC50 =4.52±0.032 μm), MAO-B (IC50 =0.059±0.002 μm), and AChE (IC50 =0.0087±0.0002 μm) inhibition without neurotoxicity. Kinetic studies revealed that compound 16 exhibits competitive and reversible inhibition against MAO-A and MAO-B, and mixed-type inhibition against AChE. Molecular docking studies further revealed insight into the possible interactions within the enzyme-inhibitor complexes. The most active compounds were found to interact with the enzymes through hydrogen bonding and hydrophobic interactions. Additionally, in silico molecular properties and ADME properties of the synthesized compounds were calculated to explore their drug-like characteristics. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Astaxanthin and Docosahexaenoic Acid Reverse the Toxicity of the Maxi-K (BK) Channel Antagonist Mycotoxin Penitrem A

PubMed Central

Goda, Amira A.; Naguib, Khayria M.; Mohamed, Magdy M.; Amra, Hassan A.; Nada, Somaia A.; Abdel-Ghaffar, Abdel-Rahman B.; Gissendanner, Chris R.; El Sayed, Khalid A.

2016-01-01

Penitrem A (PA) is a food mycotoxin produced by several terrestrial and few marine Penicillium species. PA is a potent tremorgen through selective antagonism of the calcium-dependent potassium BK (Maxi-K) channels. Discovery of natural products that can prevent the toxic effects of PA is important for food safety. Astaxanthin (AST) is a marine natural xanthophyll carotenoid with documented antioxidant activity. Unlike other common antioxidants, AST can cross blood brain barriers (BBBs), inducing neuroprotective effects. Docosahexaenoic acid (DHA) is polyunsaturated ω-3 fatty acid naturally occurring in fish and algae. DHA is essential for normal neurological and cellular development. This study evaluated the protective activity of AST and DHA against PA-induced toxicity, in vitro on Schwann cells CRL-2765 and in vivo in the worm Caenorhbitidis elegans and Sprague Dawley rat models. PA inhibited the viability of Schwann cells, with an IC50 of 22.6 μM. Dose-dependent treatments with 10–100 μM DHA significantly reversed the PA toxicity at its IC50 dose, and improved the survival of Schwann cells to 70.5%–98.8%. Similarly, dose-dependent treatments with 10–20 μM AST reversed the PA toxicity at its IC50 dose and raised these cells’ survival to 61.7%–70.5%. BK channel inhibition in the nematode C. elegans is associated with abnormal reversal locomotion. DHA and AST counteracted the in vivo PA BK channel antagonistic activity in the C. elegans model. Rats fed a PA-contaminated diet showed high levels of glutamate (GLU), aspartate (ASP), and gamma amino butyric acid (GABA), with observed necrosis or absence of Purkinjie neurons, typical of PA-induced neurotoxicity. Dopamine (DA), serotonin (5-HT), and norepinephrine (NE) levels were abnormal, Nitric Oxide (NO) and Malondialdehyde (MDA) levels were significantly increased, and total antioxidant capacity (TAC) level in serum and brain homogenates was significantly decreased in PA-treated rats. DHA and AST treatments effectively counteracted the toxic effects of PA and normalized most biochemical parameters in rats. DHA and AST can be useful food additives to prevent and reverse PA food-induced toxicity. PMID:27834847

Analysis of drug resistance during HIV RNA viraemia in the MONET trial of darunavir/ritonavir monotherapy.

PubMed

Pulido, Federico; Arribas, José R; Hill, Andrew; Van Delft, Yvon; Moecklinghoff, Christiane

2011-01-01

When patients have HIV RNA suppressed to <50 copies/ml on current treatment, switching to darunavir (DRV)/ritonavir (DRV/r) monotherapy could prevent the development of resistance to other drug classes. In the MONET trial, 256 patients with HIV RNA<50 copies/ml on current highly active antiretroviral therapy (57% with protease inhibitors [PIs] and 43% with non-nucleoside reverse transcriptase inhibitors) and no history of virological failure were randomized to DRV/r 800/100 mg once daily, either as monotherapy (monotherapy arm) or with two nucleoside reverse transcriptase inhibitors (NRTIs; triple therapy arm). All samples with HIV RNA ≥ 50 copies/ml were genotyped, and a virtual phenotype was calculated (VircoType HIV-1 assays; Virco BVBA, Mechelen, Belgium). A total of 63 patients had ≥ 1 HIV RNA result ≥ 50 copies/ml, of whom 38 were successfully genotyped. Most HIV RNA increases were transient and in the range of 50-200 copies/ml. Overall, 36 of the 38 (95%) successfully genotyped patients showed no International AIDS Society-USA major PI mutations, DRV mutations or NRTI mutations. Two patients showed some evidence of PI resistance during transient HIV RNA elevations: one patient in the monotherapy arm had a single DRV mutation (L33F) when HIV RNA was 63 copies/ml (the virus was phenotypically sensitive to DRV [fold change 0.8]) and one PI pretreated patient taking tenofovir disoproxil fumarate/emtricitabine/DRV/r had re-emergence of pre-existing NRTI (M184V) and PI (V82I and L90M) mutations after a short treatment interruption (this virus remained phenotypically sensitive to DRV/r). Both patients showed sustained HIV RNA suppression to week 48 remaining with the same treatment. Emergence of drug resistance after changing a suppressive triple antiretroviral therapy to DRV/r with or without nucleoside analogues is uncommon.

Design, synthesis, and anti-HIV-1 activity of 1-aromatic methyl-substituted 3-(3,5-dimethylbenzyl)uracil and N-3,5-dimethylbenzyl-substituted urea derivatives.

PubMed

Sakakibara, Norikazu; Baba, Masanori; Okamoto, Mika; Toyama, Masaaki; Demizu, Yosuke; Misawa, Takashi; Kurihara, Masaaki; Irie, Kohji; Kato, Yoshihisa; Maruyama, Tokumi

2015-02-01

A new series of 1-aromatic methyl-substituted 3-(3,5-dimethylbenzyl)uracil and N-3,5-dimethylbenzyl-substituted urea derivatives were synthesized and evaluated as non-nucleoside HIV-1 reverse transcriptase inhibitors. A series of new 6-azido and 6-amino derivatives of 1-substituted-3-(3,5-dimethylbenzyl)uracils were synthesized using our previously reported method, and three acyclic derivatives were synthesized from urea. The anti-HIV-1 activities of these compounds were determined based on the inhibition of virus-induced cytopathogenicity in MT-4 cells. The cytotoxicities of the compounds were evaluated using the viability of mock-infected cells. Some of these compounds showed good-to-moderate activities against HIV-1 with half maximal effective concentration (EC50) values in the submicromolar or subnanomolar range. Compared with emivirine, compound 6-amino-3-(3,5-dimethylbenzyl)-1-(4-aminobenzyl)uracil showed significant anti-HIV-1 activity with an EC50 value of 10 nM and a high selectivity index of 1923. Preliminary structure-activity relationship studies and molecular modeling analyses were carried out to explore the major interactions between HIV-1 reverse transcriptase and the potent inhibitor 6-amino-3-(3,5-dimethylbenzyl)-1-(4-aminobenzyl)uracil; these results may be important for further development of this class of compounds as anti-HIV-1 agents. The excellent activity of 6-amino-3-(3,5-dimethylbenzyl)-1-(4-aminobenzyl)uracil (EC50: 0.010 ± 0.006 µM, SI: >1923) may serve as the basis for conducting further investigations on the behavior of this class of compounds against drug-resistant mutants. © The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Design, synthesis, and anti-HIV-1 activity of 1-aromatic methyl-substituted 3-(3,5-dimethylbenzyl)uracil and N-3,5-dimethylbenzyl-substituted urea derivatives

PubMed Central

Sakakibara, Norikazu; Baba, Masanori; Okamoto, Mika; Toyama, Masaaki; Demizu, Yosuke; Misawa, Takashi; Kurihara, Masaaki; Irie, Kohji; Kato, Yoshihisa; Maruyama, Tokumi

2015-01-01

Background A new series of 1-aromatic methyl-substituted 3-(3,5-dimethylbenzyl)uracil and N-3,5-dimethylbenzyl-substituted urea derivatives were synthesized and evaluated as non-nucleoside HIV-1 reverse transcriptase inhibitors. Methods A series of new 6-azido and 6-amino derivatives of 1-substituted-3-(3,5-dimethylbenzyl)uracils were synthesized using our previously reported method, and three acyclic derivatives were synthesized from urea. The anti-HIV-1 activities of these compounds were determined based on the inhibition of virus-induced cytopathogenicity in MT-4 cells. The cytotoxicities of the compounds were evaluated using the viability of mock-infected cells. Results Some of these compounds showed good-to-moderate activities against HIV-1 with half maximal effective concentration (EC50) values in the submicromolar or subnanomolar range. Compared with emivirine, compound 6-amino-3-(3,5-dimethylbenzyl)-1-(4-aminobenzyl)uracil showed significant anti-HIV-1 activity with an EC50 value of 10 nM and a high selectivity index of 1923. Preliminary structure–activity relationship studies and molecular modeling analyses were carried out to explore the major interactions between HIV-1 reverse transcriptase and the potent inhibitor 6-amino-3-(3,5-dimethylbenzyl)-1-(4-aminobenzyl)uracil; these results may be important for further development of this class of compounds as anti-HIV-1 agents. Conclusion The excellent activity of 6-amino-3-(3,5-dimethylbenzyl)-1-(4-aminobenzyl)uracil (EC50: 0.010 ± 0.006 µM, SI: >1923) may serve as the basis for conducting further investigations on the behavior of this class of compounds against drug-resistant mutants. PMID:26149262

The Bruton tyrosine kinase inhibitor PCI-32765 ameliorates autoimmune arthritis by inhibition of multiple effector cells

PubMed Central

2011-01-01

Introduction The aim was to determine the effect of the Bruton tyrosine kinase (Btk)-selective inhibitor PCI-32765, currently in Phase I/II studies in lymphoma trials, in arthritis and immune-complex (IC) based animal models and describe the underlying cellular mechanisms. Methods PCI-32765 was administered in a series of murine IC disease models including collagen-induced arthritis (CIA), collagen antibody-induced arthritis (CAIA), reversed passive anaphylactic reaction (RPA), and passive cutaneous anaphylaxis (PCA). Clinical and pathologic features characteristic of each model were examined following treatment. PCI-32765 was then examined in assays using immune cells relevant to the pathogenesis of arthritis, and where Btk is thought to play a functional role. These included proliferation and calcium mobilization in B cells, cytokine and chemokine production in monocytes/macrophages, degranulation of mast cells and its subsequent cytokine/chemokine production. Results PCI-32765 dose-dependently and potently reversed arthritic inflammation in a therapeutic CIA model with an ED50 of 2.6 mg/kg/day. PCI-32765 also prevented clinical arthritis in CAIA models. In both models, infiltration of monocytes and macrophages into the synovium was completely inhibited and importantly, the bone and cartilage integrity of the joints were preserved. PCI-32765 reduced inflammation in the Arthus and PCA assays. In vitro, PCI-32765 inhibited BCR-activated primary B cell proliferation (IC50 = 8 nM). Following FcγR stimulation, PCI-32765 inhibited TNFα, IL-1β and IL-6 production in primary monocytes (IC50 = 2.6, 0.5, 3.9 nM, respectively). Following FcεRI stimulation of cultured human mast cells, PCI-32765 inhibited release of histamine, PGD2, TNF-α, IL-8 and MCP-1. Conclusions PCI-32765 is efficacious in CIA, and in IC models that do not depend upon autoantibody production from B cells. Thus PCI-32765 targets not only B lymphocytes but also monocytes, macrophages and mast cells, which are important Btk-expressing effector cells in arthritis. PMID:21752263

High Potency of Indolyl Aryl Sulfone Nonnucleoside Inhibitors towards Drug-Resistant Human Immunodeficiency Virus Type 1 Reverse Transcriptase Mutants Is Due to Selective Targeting of Different Mechanistic Forms of the Enzyme

PubMed Central

Cancio, Reynel; Silvestri, Romano; Ragno, Rino; Artico, Marino; De Martino, Gabriella; La Regina, Giuseppe; Crespan, Emmanuele; Zanoli, Samantha; Hübscher, Ulrich; Spadari, Silvio; Maga, Giovanni

2005-01-01

Indolyl aryl sulfone (IAS) nonnucleoside inhibitors have been shown to potently inhibit the growth of wild-type and drug-resistant human immunodeficiency virus type 1 (HIV-1), but their exact mechanism of action has not been elucidated yet. Here, we describe the mechanism of inhibition of HIV-1 reverse transcriptase (RT) by selected IAS derivatives. Our results showed that, depending on the substitutions introduced in the IAS common pharmacophore, these compounds can be made selective for different enzyme-substrate complexes. Moreover, we showed that the molecular basis for this selectivity was a different association rate of the drug to a particular enzymatic form along the reaction pathway. By comparing the activities of the different compounds against wild-type RT and the nonnucleoside reverse transcriptase inhibitor-resistant mutant Lys103Asn, it was possible to hypothesize, on the basis of their mechanism of action, a rationale for the design of drugs which could overcome the steric barrier imposed by the Lys103Asn mutation. PMID:16251294

Synthesis, Activity and Structural Analysis of Novel α-Hydroxytropolone Inhibitors of Human Immunodeficiency Virus Reverse Transcriptase-Associated Ribonuclease H

PubMed Central

Chung, Suhman; Himmel, Daniel M.; Jiang, Jian-Kang; Wojtak, Krzysztof; Bauman, Joseph D.; Rausch, Jason W.; Wilson, Jennifer A.; Beutler, John A.; Thomas, Craig J.; Arnold, Eddy; Le Grice, Stuart F.J.

2011-01-01

The α-hydroxytroplone, manicol (5,7-dihydroxy-2-isopropenyl-9-methyl-1,2,3,4-tetrahydro-benzocyclohepten-6-one) potently and specifically inhibits ribonuclease H (RNase H) activity of human immunodeficiency virus reverse transcriptase (HIV RT) in vitro. However, manicol was ineffective in reducing virus replication in culture. Ongoing efforts to improve the potency and specificity over the lead compound led us to synthesize 14 manicol derivatives that retain the divalent metal-chelating α-hydroxytropolone pharmacophore. These efforts were augmented by a high resolution structure of p66/p51 HIV-1 RT containing the nonnucleoside reverse transcriptase inhibitor (NNRTI), TMC278 and manicol in the DNA polymerase and RNase H active sites, respectively. We demonstrate here that several modified α-hydroxytropolones exhibit antiviral activity at non-cytotoxic concentrations. Inclusion of RNase H active site mutants indicated that manicol analogs can occupy an additional site in or around the DNA polymerase catalytic center. Collectively, our studies will promote future structure-based design of improved α-hydroxytropolones to complement the NRTI and NNRTI currently in clinical use. PMID:21568335

Structure-based virtual screening efforts against HIV-1 reverse transcriptase to introduce the new potent non-nucleoside reverse transcriptase inhibitor

NASA Astrophysics Data System (ADS)

Hosseini, Yaser; Mollica, Adriano; Mirzaie, Sako

2016-12-01

The human immunodeficiency virus (HIV) which is strictly related to the development of AIDS, is treated by a cocktail of drugs, but due its high propensity gain drug resistance, the rational development of new medicine is highly desired. Among the different mechanism of action we selected the reverse transcriptase (RT) inhibition, for our studies. With the aim to identify new chemical entities to be used for further rational drug design, a set of 3000 molecules from the Zinc Database have been screened by docking experiments using AutoDock Vina software. The best ranked compounds with respect of the crystallographic inhibitor MK-4965 resulted to be five compounds, and the best among them was further tested by molecular dynamics (MD) simulation. Our results indicate that comp1 has a stronger interaction with the subsite p66 of RT than MK-4965 and that both are able to stabilize specific conformational changes of the RT 3D structure, which may explain their activity as inhibitors. Therefore comp1 could be a good candidate for biological tests and further development.

Recent advances in the development of next generation non-nucleoside reverse transcriptase inhibitors.

PubMed

Tarby, Christine M

2004-01-01

Since their discovery, non-nucleoside reverse transcriptase inhibitors (NNRTIs) have become one of the cornerstones of highly active anti-retroviral therapy (HAART). Currently, three NNRTI agents, efavirenz, nevirapine and delavirdine are commercially available. Efavirenz and nevirapine, used in combination with nucleoside reverse transcriptase inhibitors (NRTIs), provide durable regimens with efficacy comparable to protease inhibitor (PI) containing therapies. When virological failure occurs following treatment with an NNRTI, the resistance mutations can confer reduced sensitivity to the entire agent class. Therefore, the strategy for the development of next generation NNRTIs has been to focus on compounds which have improved potencies against the clinically relevant viral mutants. Agents with improved virological profiles and which maintain the ease of administration and favorable safety profiles of the current agents should find use in anti-retroviral naïve patients as well as in components of salvage regimens in the anti-retroviral experienced patient. This review summarizes the recent developments with compounds in clinical trials as of January 2002 as well as to summarize information on new agents appearing in the primary and patent literature between January 2001 and December 2002.

Polyurethane intravaginal ring for controlled delivery of dapivirine, a nonnucleoside reverse transcriptase inhibitor of HIV-1.

PubMed

Gupta, Kavita M; Pearce, Serena M; Poursaid, Azadeh E; Aliyar, Hyder A; Tresco, Patrick A; Mitchnik, Mark A; Kiser, Patrick F

2008-10-01

Women-controlled methods for prevention of male-to-female sexual transmission of HIV-1 are urgently needed. Providing inhibitory concentrations of HIV-1 reverse transcriptase inhibitors to impede the replication of the virus in the female genital tissue offers a mechanism for prophylaxis of HIV-1. To this end, an intravaginal ring device that can provide long duration delivery of dapivirine, a nonnucleoside reverse transcriptase inhibitor of HIV-1, was developed utilizing a medical-grade polyether urethane. Monolithic intravaginal rings were fabricated and sustained release with cumulative flux linear with time was demonstrated under sink conditions for a period of 30 days. The release rate was directly proportional to the amount of drug loaded. Another release study conducted for a week utilizing liposome dispersions as sink conditions, to mimic the partitioning of dapivirine into vaginal tissue, also demonstrated release rates constant with time. These results qualify polyether urethanes for development of intravaginal rings for sustained delivery of microbicidal agents. (c) 2008 Wiley-Liss, Inc. and the American Pharmacists Association

A Novel Leu92 Mutant of HIV-1 Reverse Transcriptase with a Selective Deficiency in Strand Transfer Causes a Loss of Viral Replication.

PubMed

Herzig, Eytan; Voronin, Nickolay; Kucherenko, Nataly; Hizi, Amnon

2015-08-01

The process of reverse transcription (RTN) in retroviruses is essential to the viral life cycle. This key process is catalyzed exclusively by the viral reverse transcriptase (RT) that copies the viral RNA into DNA by its DNA polymerase activity, while concomitantly removing the original RNA template by its RNase H activity. During RTN, the combination between DNA synthesis and RNA hydrolysis leads to strand transfers (or template switches) that are critical for the completion of RTN. The balance between these RT-driven activities was considered to be the sole reason for strand transfers. Nevertheless, we show here that a specific mutation in HIV-1 RT (L92P) that does not affect the DNA polymerase and RNase H activities abolishes strand transfer. There is also a good correlation between this complete loss of the RT's strand transfer to the loss of the DNA clamp activity of the RT, discovered recently by us. This finding indicates a mechanistic linkage between these two functions and that they are both direct and unique functions of the RT (apart from DNA synthesis and RNA degradation). Furthermore, when the RT's L92P mutant was introduced into an infectious HIV-1 clone, it lost viral replication, due to inefficient intracellular strand transfers during RTN, thus supporting the in vitro data. As far as we know, this is the first report on RT mutants that specifically and directly impair RT-associated strand transfers. Therefore, targeting residue Leu92 may be helpful in selectively blocking this RT activity and consequently HIV-1 infectivity and pathogenesis. Reverse transcription in retroviruses is essential for the viral life cycle. This multistep process is catalyzed by viral reverse transcriptase, which copies the viral RNA into DNA by its DNA polymerase activity (while concomitantly removing the RNA template by its RNase H activity). The combination and balance between synthesis and hydrolysis lead to strand transfers that are critical for reverse transcription completion. We show here for the first time that a single mutation in HIV-1 reverse transcriptase (L92P) selectively abolishes strand transfers without affecting the enzyme's DNA polymerase and RNase H functions. When this mutation was introduced into an infectious HIV-1 clone, viral replication was lost due to an impaired intracellular strand transfer, thus supporting the in vitro data. Therefore, finding novel drugs that target HIV-1 reverse transcriptase Leu92 may be beneficial for developing new potent and selective inhibitors of retroviral reverse transcription that will obstruct HIV-1 infectivity. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Identification of a Pyridoxine-Derived Small-Molecule Inhibitor Targeting Dengue Virus RNA-Dependent RNA Polymerase.

PubMed

Xu, Hong-Tao; Colby-Germinario, Susan P; Hassounah, Said; Quashie, Peter K; Han, Yingshan; Oliveira, Maureen; Stranix, Brent R; Wainberg, Mark A

2016-01-01

The viral RNA-dependent RNA polymerase (RdRp) activity of the dengue virus (DENV) NS5 protein is an attractive target for drug design. Here, we report the identification of a novel class of inhibitor (i.e., an active-site metal ion chelator) that acts against DENV RdRp activity. DENV RdRp utilizes a two-metal-ion mechanism of catalysis; therefore, we constructed a small library of compounds, through mechanism-based drug design, aimed at chelating divalent metal ions in the catalytic site of DENV RdRp. We now describe a pyridoxine-derived small-molecule inhibitor that targets DENV RdRp and show that 5-benzenesulfonylmethyl-3-hydroxy-4-hydroxymethyl-pyridine-2-carboxylic acid hydroxyamide (termed DMB220) inhibited the RdRp activity of DENV serotypes 1 to 4 at low micromolar 50% inhibitory concentrations (IC50s of 5 to 6.7 μM) in an enzymatic assay. The antiviral activity of DMB220 against DENV infection was also verified in a cell-based assay and showed a 50% effective concentration (EC50) of <3 μM. Enzyme assays proved that DMB220 was competitive with nucleotide incorporation. DMB220 did not inhibit the enzymatic activity of recombinant HIV-1 reverse transcriptase and showed only weak inhibition of HIV-1 integrase strand transfer activity, indicating high specificity for DENV RdRp. S600T substitution in the DENV RdRp, which was previously shown to confer resistance to nucleoside analogue inhibitors (NI), conferred 3-fold hypersusceptibility to DMB220, and enzymatic analyses showed that this hypersusceptibility may arise from the decreased binding/incorporation efficiency of the natural NTP substrate without significantly impacting inhibitor binding. Thus, metal ion chelation at the active site of DENV RdRp represents a viable anti-DENV strategy, and DMB220 is the first of a new class of DENV inhibitor. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

In vitro and in vivo characterization of the anticancer activity of Thai stingless bee (Tetragonula laeviceps) cerumen

PubMed Central

Nugitrangson, Pongvit; Puthong, Songchan; Iempridee, Tawin; Pimtong, Wittaya; Chanchao, Chanpen

2015-01-01

Tetragonula laeviceps cerumen was sequentially extracted with 80% (v/v) methanol, dichloromethane, and hexane and also in the reverse order. By the MTT assay and the respective 50% inhibition concentration value, the most active fraction was further purified to apparent homogeneity by bioassay-guided silica gel column chromatography. α-Mangostin was identified by high-resolution electrospray ionization mass spectrometry and nuclear magnetic resonance analyses. It had a potent cytotoxicity against the BT474, Chago, Hep-G2, KATO-III, and SW620 cell lines (IC50 values of 1.22 ± 0.03, 2.25 ± 0.20, 0.94 ± 0.01, 0.88 ± 0.16, and 1.50 ± 0.39 µmol/L, respectively). The in vitro cytotoxicity of α-mangostin against the five human cancer cell lines and primary fibroblasts was further characterized by real-time impedance-based analysis. Interestingly, α-mangostin was more cytotoxic against the cancer-derived cell lines than against the primary fibroblasts. Later, the migration assay was performed by continuously measuring the attachment of cells to the plate electrodes at the bottom of the transwell membrane. The combined caspase-3 and -7 activities were assayed by the Caspase-Glo® 3/7 kit. It showed that the cytotoxic mechanism involved caspase-independent apoptosis, while at low (non-toxic) concentrations α-mangostin did not significantly alter cell migration. Furthermore, the in vivo cytotoxicity and angiogenesis were determined by alkaline phosphatase staining in zebrafish embryos along with monitoring changes in the transcript expression level of two genes involved in angiogenesis (vegfaa and vegfr2) by quantitative real-time reverse transcriptase- polymerase chain reaction. It was found that the in vivo cytotoxicity of α-mangostin against zebrafish embryos had a 50% lethal concentration of 9.4 µM, but no anti-angiogenic properties were observed in zebrafish embryos at 9 and 12 µM even though it downregulated the expression of vegfaa and vegfr2 transcripts. Thus, α-mangostin is a major active compound with a potential anticancer activity in T. laeviceps cerumen in Thailand. PMID:26290139

In vitro and in vivo characterization of the anticancer activity of Thai stingless bee (Tetragonula laeviceps) cerumen.

PubMed

Nugitrangson, Pongvit; Puthong, Songchan; Iempridee, Tawin; Pimtong, Wittaya; Pornpakakul, Surachai; Chanchao, Chanpen

2016-01-01

Tetragonula laeviceps cerumen was sequentially extracted with 80% (v/v) methanol, dichloromethane, and hexane and also in the reverse order. By the MTT assay and the respective 50% inhibition concentration value, the most active fraction was further purified to apparent homogeneity by bioassay-guided silica gel column chromatography. α-Mangostin was identified by high-resolution electrospray ionization mass spectrometry and nuclear magnetic resonance analyses. It had a potent cytotoxicity against the BT474, Chago, Hep-G2, KATO-III, and SW620 cell lines (IC50 values of 1.22 ± 0.03, 2.25 ± 0.20, 0.94 ± 0.01, 0.88 ± 0.16, and 1.50 ± 0.39 µmol/L, respectively). The in vitro cytotoxicity of α-mangostin against the five human cancer cell lines and primary fibroblasts was further characterized by real-time impedance-based analysis. Interestingly, α-mangostin was more cytotoxic against the cancer-derived cell lines than against the primary fibroblasts. Later, the migration assay was performed by continuously measuring the attachment of cells to the plate electrodes at the bottom of the transwell membrane. The combined caspase-3 and -7 activities were assayed by the Caspase-Glo® 3/7 kit. It showed that the cytotoxic mechanism involved caspase-independent apoptosis, while at low (non-toxic) concentrations α-mangostin did not significantly alter cell migration. Furthermore, the in vivo cytotoxicity and angiogenesis were determined by alkaline phosphatase staining in zebrafish embryos along with monitoring changes in the transcript expression level of two genes involved in angiogenesis (vegfaa and vegfr2) by quantitative real-time reverse transcriptase- polymerase chain reaction. It was found that the in vivo cytotoxicity of α-mangostin against zebrafish embryos had a 50% lethal concentration of 9.4 µM, but no anti-angiogenic properties were observed in zebrafish embryos at 9 and 12 µM even though it downregulated the expression of vegfaa and vegfr2 transcripts. Thus, α-mangostin is a major active compound with a potential anticancer activity in T. laeviceps cerumen in Thailand. © 2015 by the Society for Experimental Biology and Medicine.

Gamma-irradiated bacterial preparation having anti-tumor activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vass, A.A.; Tyndall, R.L.; Terzaghi-Howe, P.

1999-11-16

This application describes a bacterial preparation from Pseudomonas species isolated {number{underscore}sign}15 ATCC 55638 that has been exposed to gamma radiation exhibits cytotoxicity that is specific for neoplastic carcinoma cells. A method for obtaining a bacterial preparation having antitumor activity consists of suspending a bacterial isolate in media and exposing the suspension to gamma radiation. A bacterial preparation of an aged culture of an amoeba-associated bacteria exhibits anti-reverse transcriptase activity. A method for obtaining a bacterial preparation having anti-reverse transcriptase activity from an amoeba-associated bacterial isolate grown to stationary phase is disclosed.

Tenofovir-related nephrotoxicity: case report and review of the literature.

PubMed

James, Christopher W; Steinhaus, Mary C; Szabo, Susan; Dressier, Robert M

2004-03-01

Tenofovir is a nucleotide reverse transcriptase inhibitor for treatment of human immunodeficiency virus (HIV) infection. Several cases of renal failure associated with tenofovir therapy recently have been reported. A 54-year-old man with HIV experienced decreasing renal function and Fanconi's syndrome secondary to tenofovir therapy. His condition gradually improved after discontinuation of the drug. The available medical literature for reported cases of tenofovir-related nephrotoxicity indicates that this complication is apparently rare. However, our case report and literature review underscore the importance of monitoring renal function when treating patients with any nucleotide reverse transcriptase inhibitor.

Potent inhibition of monoamine oxidase A by decursin from Angelica gigas Nakai and by wogonin from Scutellaria baicalensis Georgi.

PubMed

Lee, Hyun Woo; Ryu, Hyung Won; Kang, Myung-Gyun; Park, Daeui; Lee, Hanna; Shin, Heung Mook; Oh, Sei-Ryang; Kim, Hoon

2017-04-01

During the ongoing search for new monoamine oxidase (MAO) inhibitors, five coumarin derivatives and eight flavonoids were isolated from the roots of Angelica gigas Nakai and Scutellaria baicalensis Georgi, respectively. Of the phytochemicals, decursin (4) was found to potently and selectively inhibit human MAO-A (IC 50 =1.89μM). The IC 50 value of 4 for MAO-A belonged to the lowest group in herbal sources and was similar to that of toloxatone (1.78μM), a marketed drug. Wogonin (11) effectively inhibited MAO-A and MAO-B (IC 50 =6.35 and 20.8μM, respectively). Furthermore, compounds 5 (decursinol angelate) and 10 (baicalein) were observed to selectively and moderately inhibit MAO-A. In addition, compound 4 reversibly and competitively inhibited MAO-A with a K i of 0.17μM. Compound 11 also competitively inhibited MAO-A and MAO-B (K i =0.56 and 1.96μM, respectively). Molecular docking simulation revealed that 4 interacts with Asn181 residue of MAO-A or Asn116 residue of MAO-B by formation of hydrogen bond. The findings suggest compounds 4 and 11 be considered as new potent and reversible MAO-A inhibitors or useful lead compounds for the developments of MAO inhibitors for the treatment of disorders like depression, Parkinson's disease and Alzheimer disease. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis and Biological Evaluation of Novel N-Aryl-ω-(Benzoazol-2-yl)-Sulfanylalkanamides as Dual Inhibitors of α-Glucosidase and Protein Tyrosine Phosphatase 1B.

PubMed

Wang, Mei-Yan; Cheng, Xian-Chao; Chen, Xiu-Bo; Li, Yu; Zang, Lan-Lan; Duan, Yu-Qing; Chen, Ming-Zhu; Yu, Peng; Sun, Hua; Wang, Run-Ling

2018-05-09

α-Glucosidase is known to catalyze the digestion of carbohydrates and release free glucose into the digestive tract. Protein tyrosine phosphatase 1B (PTP1B) is engaged in the dephosphorylation of the insulin receptor and regulation of insulin sensitivity. Therefore, dual antagonists by targeting both α-glucosidase and PTP1B may be potential candidates for type 2 diabetes therapy. In this work, three series of novel N-aryl-ω-(benzoazol-2-yl)-sulfanylalkanamides were synthesized and assayed for their α-glucosidase and PTP1B inhibitory activities, respectively. Compound 3l, exhibiting the most effective α-glucosidase inhibitory activity (IC 50 = 10.96 μM (3l), IC 50 = 51.32 μM (Acarbose), IC 50 = 18.22 μM (Ursolic acid)) and potent PTP1B inhibitory activity (IC 50 = 13.46 μM (3l), IC 50 = 14.50 μM (Ursolic acid)), was identified as a novel dual inhibitor of α-glucosidase and PTP1B. Furthermore, 3l is a highly selective PTP1B inhibitor since no inhibition was showed by 3l at 100 μM against PTP-MEG2, TCPTP, SHP2, or SHP1. Subsequent kinetic analysis revealed 3l inhibited α-glucosidase in a reversible and mixed manner. Molecular docking study indicated that hydrogen bonds, van der Waals, charge interactions and Pi-cation interactions all contributed to interactions between 3l and α-glucosidase/PTP1B. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Sex-dependent metabolism of nevirapine in rats: impact on plasma levels, pharmacokinetics and interaction with nortriptyline.

PubMed

Usach, Iris; Compañ, Pablo; Peris, José-Esteban

2018-05-01

Nevirapine (NVP) is a non-nucleoside reverse transcriptase inhibitor (NNRTI) widely used in the treatment of human immunodeficiency virus type 1 (HIV-1) and is the first-choice NNRTI during pregnancy. NVP shows a sex dimorphic profile in humans with sex differences in bioavailability, biotransformation and toxicity. In this study, sex differences in NVP metabolism and inhibition of NVP metabolism by the antidepressant nortriptyline (NT) were evaluated using rats as experimental animals. NVP was administered orally to male and female rats and sex differences in plasma levels and pharmacokinetic parameters were analysed. NVP plasma levels were higher in female compared with male rats, and pharmacokinetic parameters such as maximum plasma concentration (C max ), time to C max (T max ), half-life (t 1/2 ) and area under the plasma concentration-time curve from the time of dosing to the last measurable concentration (AUC last ) showed ca. 4-, 5-, 7- and 22-fold higher values in female rats. In vitro experiments carried out with hepatic microsomes confirmed slower NVP metabolism in female rats, with a maximum velocity (V max ) 2-fold lower than in male hepatic microsomes. The major metabolite in both sexes was 12-hydroxynevirapine (12-OH-NVP), with the V max for this metabolite being 15-fold lower in female compared with male rat hepatic microsomes. Inhibition of NVP metabolism by NT was similar in both sexes, with statistically non-significant differences in 50% inhibitory concentration (IC 50 ) values. In summary, NVP is metabolised more slowly in female compared with male rats, but the inhibitory effect of NT is similar in both sexes. Copyright © 2018 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

Intracellular Activation of Tenofovir Alafenamide and the Effect of Viral and Host Protease Inhibitors

PubMed Central

Bam, Rujuta A.; Willkom, Madeleine; Frey, Christian R.; Tsai, Luong; Stray, Kirsten M.; Yant, Stephen R.; Cihlar, Tomas

2015-01-01

Tenofovir alafenamide fumarate (TAF) is an oral phosphonoamidate prodrug of the HIV reverse transcriptase nucleotide inhibitor tenofovir (TFV). Previous studies suggested a principal role for the lysosomal serine protease cathepsin A (CatA) in the intracellular activation of TAF. Here we further investigated the role of CatA and other human hydrolases in the metabolism of TAF. Overexpression of CatA or liver carboxylesterase 1 (Ces1) in HEK293T cells increased intracellular TAF hydrolysis 2- and 5-fold, respectively. Knockdown of CatA expression with RNA interference (RNAi) in HeLa cells reduced intracellular TAF metabolism 5-fold. Additionally, the anti-HIV activity and the rate of CatA hydrolysis showed good correlation within a large set of TFV phosphonoamidate prodrugs. The covalent hepatitis C virus (HCV) protease inhibitors (PIs) telaprevir and boceprevir potently inhibited CatA-mediated TAF activation (50% inhibitory concentration [IC50] = 0.27 and 0.16 μM, respectively) in vitro and also reduced its anti-HIV activity in primary human CD4+ T lymphocytes (21- and 3-fold, respectively) at pharmacologically relevant concentrations. In contrast, there was no inhibition of CatA or any significant effect on anti-HIV activity of TAF observed with cobicistat, noncovalent HIV and HCV PIs, or various prescribed inhibitors of host serine proteases. Collectively, these studies confirm that CatA plays a pivotal role in the intracellular metabolism of TAF, whereas the liver esterase Ces1 likely contributes to the hepatic activation of TAF. Moreover, this work demonstrates that a wide range of viral and host PIs, with the exception of telaprevir and boceprevir, do not interfere with the antiretroviral activity of TAF. PMID:26503655

Direct CRISPR spacer acquisition from RNA by a natural reverse-transcriptase-Cas1 fusion protein

PubMed Central

Sidote, David J.; Markham, Laura M.; Sanchez-Amat, Antonio; Bhaya, Devaki; Lambowitz, Alan M.; Fire, Andrew Z.

2016-01-01

CRISPR (Clustered Regularly Interspaced Short Palindromic Repeat) systems mediate adaptive immunity in diverse prokaryotes. CRISPR-associated Cas1 and Cas2 proteins have been shown to enable adaptation to new threats in Type I and II CRISPR systems by the acquisition of short segments of DNA (“spacers”) from invasive elements. In several Type III CRISPR systems, Cas1 is naturally fused to a reverse transcriptase (RT). In the marine bacterium Marinomonas mediterranea (MMB-1), we show that an RT-Cas1 fusion enables the acquisition of RNA spacers in vivo in an RT-dependent manner. In vitro, the MMB-1 RT-Cas1 and Cas2 proteins catalyze ligation of RNA segments into the CRISPR array, followed by reverse transcription. These observations outline a host-mediated mechanism for reverse information flow from RNA to DNA. PMID:26917774

Simultaneous determination of the HIV nucleoside analogue reverse transcriptase inhibitors lamivudine, didanosine, stavudine, zidovudine and abacavir in human plasma by reversed phase high performance liquid chromatography.

PubMed

Verweij-van Wissen, C P W G M; Aarnoutse, R E; Burger, D M

2005-02-25

A reversed phase high performance liquid chromatography method was developed for the simultaneous quantitative determination of the nucleoside reverse transcriptase inhibitors (NRTIs) lamivudine, didanosine, stavudine, zidovudine and abacavir in plasma. The method involved solid-phase extraction with Oasis MAX cartridges from plasma, followed by high performance liquid chromatography with a SymmetryShield RP 18 column and ultraviolet detection set at a wavelength of 260 nm. The assay was validated over the concentration range of 0.015-5 mg/l for all five NRTIs. The average accuracies for the assay were 92-102%, inter- and intra-day coefficients of variation (CV) were <2.5% and extraction recoveries were higher than 97%. This method proved to be simple, accurate and precise, and is currently in use in our laboratory for the quantitative analysis of NRTIs in plasma.

Mechanisms Used for Genomic Proliferation by Thermophilic Group II Introns

PubMed Central

Mohr, Georg; Ghanem, Eman; Lambowitz, Alan M.

2010-01-01

Mobile group II introns, which are found in bacterial and organellar genomes, are site-specific retroelments hypothesized to be evolutionary ancestors of spliceosomal introns and retrotransposons in higher organisms. Most bacteria, however, contain no more than one or a few group II introns, making it unclear how introns could have proliferated to higher copy numbers in eukaryotic genomes. An exception is the thermophilic cyanobacterium Thermosynechococcus elongatus, which contains 28 closely related copies of a group II intron, constituting ∼1.3% of the genome. Here, by using a combination of bioinformatics and mobility assays at different temperatures, we identified mechanisms that contribute to the proliferation of T. elongatus group II introns. These mechanisms include divergence of DNA target specificity to avoid target site saturation; adaptation of some intron-encoded reverse transcriptases to splice and mobilize multiple degenerate introns that do not encode reverse transcriptases, leading to a common splicing apparatus; and preferential insertion within other mobile introns or insertion elements, which provide new unoccupied sites in expanding non-essential DNA regions. Additionally, unlike mesophilic group II introns, the thermophilic T. elongatus introns rely on elevated temperatures to help promote DNA strand separation, enabling access to a larger number of DNA target sites by base pairing of the intron RNA, with minimal constraint from the reverse transcriptase. Our results provide insight into group II intron proliferation mechanisms and show that higher temperatures, which are thought to have prevailed on Earth during the emergence of eukaryotes, favor intron proliferation by increasing the accessibility of DNA target sites. We also identify actively mobile thermophilic introns, which may be useful for structural studies, gene targeting in thermophiles, and as a source of thermostable reverse transcriptases. PMID:20543989

Antiretroviral Drug Use in a Cross-Sectional Population Survey in Africa: NIMH Project Accept (HPTN 043).

PubMed

Fogel, Jessica M; Clarke, William; Kulich, Michal; Piwowar-Manning, Estelle; Breaud, Autumn; Olson, Matthew T; Marzinke, Mark A; Laeyendecker, Oliver; Fiamma, Agnès; Donnell, Deborah; Mbwambo, Jessie K K; Richter, Linda; Gray, Glenda; Sweat, Michael; Coates, Thomas J; Eshleman, Susan H

2017-02-01

Antiretroviral (ARV) drug treatment benefits the treated individual and can prevent HIV transmission. We assessed ARV drug use in a community-randomized trial that evaluated the impact of behavioral interventions on HIV incidence. Samples were collected in a cross-sectional survey after a 3-year intervention period. ARV drug testing was performed using samples from HIV-infected adults at 4 study sites (Zimbabwe; Tanzania; KwaZulu-Natal and Soweto, South Africa; survey period 2009-2011) using an assay that detects 20 ARV drugs (6 nucleoside/nucleotide reverse transcriptase inhibitors, 3 nonnucleoside reverse transcriptase inhibitors, and 9 protease inhibitors; maraviroc; raltegravir). ARV drugs were detected in 2011 (27.4%) of 7347 samples; 88.1% had 1 nonnucleoside reverse transcriptase inhibitors ± 1-2 nucleoside/nucleotide reverse transcriptase inhibitors. ARV drug detection was associated with sex (women>men), pregnancy, older age (>24 years), and study site (P < 0.0001 for all 4 variables). ARV drugs were also more frequently detected in adults who were widowed (P = 0.006) or unemployed (P = 0.02). ARV drug use was more frequent in intervention versus control communities early in the survey (P = 0.01), with a significant increase in control (P = 0.004) but not in intervention communities during the survey period. In KwaZulu-Natal, a 1% increase in ARV drug use was associated with a 0.14% absolute decrease in HIV incidence (P = 0.018). This study used an objective, biomedical approach to assess ARV drug use on a population level. This analysis identified factors associated with ARV drug use and provided information on ARV drug use over time. ARV drug use was associated with lower HIV incidence at 1 study site.

Update on HIV-1 acquired and transmitted drug resistance in Africa.

PubMed

Ssemwanga, Deogratius; Lihana, Raphael W; Ugoji, Chinenye; Abimiku, Alash'le; Nkengasong, John; Dakum, Patrick; Ndembi, Nicaise

2015-01-01

The last ten years have witnessed a significant scale-up and access to antiretroviral therapy in Africa, which has improved patient quality of life and survival. One major challenge associated with increased access to antiretroviral therapy is the development of antiretroviral resistance due to inconsistent drug supply and/or poor patient adherence. We review the current state of both acquired and transmitted drug resistance in Africa over the past ten years (2001-2011) to identify drug resistance associated with the different drug regimens used on the continent and to help guide affordable strategies for drug resistance surveillance. A total of 161 references (153 articles, six reports and two conference abstracts) were reviewed. Antiretroviral resistance data was available for 40 of 53 African countries. A total of 5,541 adult patients from 99 studies in Africa were included in this analysis. The pooled prevalence of drug resistance mutations in Africa was 10.6%, and Central Africa had the highest prevalence of 54.9%. The highest prevalence of nucleoside reverse transcriptase inhibitor mutations was in the west (55.3%) and central (54.8%) areas; nonnucleoside reverse transcriptase inhibitor mutations were highest in East Africa (57.0%) and protease inhibitors mutations highest in Southern Africa (16.3%). The major nucleoside reverse transcriptase inhibitor mutation in all four African regions was M184V. Major nonnucleoside reverse transcriptase inhibitor as well as protease inhibitor mutations varied by region. The prevalence of drug resistance has remained low in several African countries although the emergence of drug resistance mutations varied across countries. Continued surveillance of antiretroviral therapy resistance remains crucial in gauging the effectiveness of country antiretroviral therapy programs and strategizing on effective and affordable strategies for successful treatment.

Detection of SYT-SSX mutant transcripts in formalin-fixed paraffin-embedded sarcoma tissues using one-step reverse transcriptase real-time PCR.

PubMed

Norlelawati, A T; Mohd Danial, G; Nora, H; Nadia, O; Zatur Rawihah, K; Nor Zamzila, A; Naznin, M

2016-04-01

Synovial sarcoma (SS) is a rare cancer and accounts for 5-10% of adult soft tissue sarcomas. Making an accurate diagnosis is difficult due to the overlapping histological features of SS with other types of sarcomas and the non-specific immunohistochemistry profile findings. Molecular testing is thus considered necessary to confirm the diagnosis since more than 90% of SS cases carry the transcript of t(X;18)(p11.2;q11.2). The purpose of this study is to diagnose SS at molecular level by testing for t(X;18) fusion-transcript expression through One-step reverse transcriptase real-time Polymerase Chain Reaction (PCR). Formalin-fixed paraffin-embedded tissue blocks of 23 cases of soft tissue sarcomas, which included 5 and 8 cases reported as SS as the primary diagnosis and differential diagnosis respectively, were retrieved from the Department of Pathology, Tengku Ampuan Afzan Hospital, Kuantan, Pahang. RNA was purified from the tissue block sections and then subjected to One-step reverse transcriptase real-time PCR using sequence specific hydrolysis probes for simultaneous detection of either SYT-SSX1 or SYT-SSX2 fusion transcript. Of the 23 cases, 4 cases were found to be positive for SYT-SSX fusion transcript in which 2 were diagnosed as SS whereas in the 2 other cases, SS was the differential diagnosis. Three cases were excluded due to failure of both amplification assays SYT-SSX and control β-2-microglobulin. The remaining 16 cases were negative for the fusion transcript. This study has shown that the application of One-Step reverse transcriptase real time PCR for the detection SYT-SSX transcript is feasible as an aid in confirming the diagnosis of synovial sarcoma.

Anti-adenoviral effect of anti-HIV agents in vitro in serotypes inducing keratoconjunctivitis.

PubMed

Uchio, Eiichi; Fuchigami, Aki; Kadonosono, Kazuaki; Hayashi, Akio; Ishiko, Hiroaki; Aoki, Koki; Ohno, Shigeaki

2007-09-01

Around one million people are affected by adenoviral keratoconjunctivitis a year in Japan, and it is recognized as one of the major pathogens of ophthalmological nosocomial infection worldwide. Although cidofovir can be used systemically for immunocompromised patients with disseminated adenoviral infection, no specific anti-adenoviral agent has been established for the treatment of adenoviral infection. We evaluated the anti-adenoviral effect of anti-HIV (human immunodeficiency virus) agents in this study. Five anti-HIV agents (zalcitabine, stavudine, nevirapine, indinavir and amprenavir) were subjected to in vitro evaluation. A549 cells were used for viral cell culture, and adenovirus serotypes 3, 4, 8, 19 and 37 were used. After calculating CC(50) (50% cytotoxic concentration) of each agent by MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) method, we cultured adenovirus with the agents for seven days and quantitatively measured extracted adenoviral DNA by real-time PCR. Among the anti-HIV drugs, zalcitabine and stavudine, both nucleoside reverse transcriptase inhibitors, showed significant anti-adenoviral activity. In contrast, nevirapine, a non-nucleoside reverse transcriptase inhibitor, and indinavir and amprenavir, which are both protease inhibitors, were ineffective against adenovirus. These results indicate that zalcitabine and stavudine are possible candidates for the local and systemic treatment of adenoviral infection, and the anti-adenoviral effect might depend on the pharmacological properties of anti-HIV agents. The chemical properties on the clinical safety for systemic and local application need to be determined in order to for these drugs to be accepted for the treatment of adenovirus in clinical settings.

Quantitative Assessment of the Sensitivity of Various Commercial Reverse Transcriptases Based on Armored HIV RNA

PubMed Central

Okello, John B. A.; Rodriguez, Linda; Poinar, Debi; Bos, Kirsten; Okwi, Andrew L.; Bimenya, Gabriel S.; Sewankambo, Nelson K.; Henry, Kenneth R.; Kuch, Melanie; Poinar, Hendrik N.

2010-01-01

Background The in-vitro reverse transcription of RNA to its complementary DNA, catalyzed by the enzyme reverse transcriptase, is the most fundamental step in the quantitative RNA detection in genomic studies. As such, this step should be as analytically sensitive, efficient and reproducible as possible, especially when dealing with degraded or low copy RNA samples. While there are many reverse transcriptases in the market, all claiming to be highly sensitive, there is need for a systematic independent comparison of their applicability in quantification of rare RNA transcripts or low copy RNA, such as those obtained from archival tissues. Methodology/Principal Findings We performed RT-qPCR to assess the sensitivity and reproducibility of 11 commercially available reverse transcriptases in cDNA synthesis from low copy number RNA levels. As target RNA, we used a serially known number of Armored HIV RNA molecules, and observed that 9 enzymes we tested were consistently sensitive to ∼1,000 copies, seven of which were sensitive to ∼100 copies, while only 5 were sensitive to ∼10 RNA template copies across all replicates tested. Despite their demonstrated sensitivity, these five best performing enzymes (Accuscript, HIV-RT, M-MLV, Superscript III and Thermoscript) showed considerable variation in their reproducibility as well as their overall amplification efficiency. Accuscript and Superscript III were the most sensitive and consistent within runs, with Accuscript and Superscript II ranking as the most reproducible enzymes between assays. Conclusions/Significance We therefore recommend the use of Accuscript or Superscript III when dealing with low copy number RNA levels, and suggest purification of the RT reactions prior to downstream applications (eg qPCR) to augment detection. Although the results presented in this study were based on a viral RNA surrogate, and applied to nucleic acid lysates derived from archival formalin-fixed paraffin embedded tissue, their relative performance on RNA obtained from other tissue types may vary, and needs future evaluation. PMID:21085668

[Determination of the healing effect of Piper aduncum (spiked pepper or matico) on human fibroblasts].

PubMed

Paco, Karen; Ponce-Soto, Luis Alberto; Lopez-Ilasaca, Marco; Aguilar, José L

2016-01-01

To evaluate the healing effect of a Piper aduncum ethanol-water extract on an adult human dermal fibroblast cell line (hDFa). After obtaining the extract via solid-liquid extraction, concentration, and lyophilization, extract proteins were purified using reverse phase high-performance liquid chromatography, identified using tandem mass spectrometry of tryptic peptides, and analyzed using MALDI-TOF-TOF on an ABSciex4800 mass spectrometer. Half maximum effective concentration values (EC50), half maximum inhibiting concentration (IC50), and percentages of cell proliferation were determined using tetrazolium salt assays. Cell migration was evaluated using a "scratch assay". Growth factor expression in cells was analyzed via quantitative real-time reverse transcription polymerase chain reaction. Against the hDFa cell line, the extract had an IC50 of 200 μg/mL and EC50 of 103.5 µg/mL. In the proliferation assay, protein K2 (obtained from the extract) exhibited increased proliferative activity relative to other treatments (1 µg/mL); this agent also exhibited increased activity (50 µg/mL) in the fibroblast migration assay.Furthermore, the relative expression of platelet-derived growth factor increased by 8.6-fold in the presence of K2 protein relative to the control. The hydroethanolic extract of Piper aduncum and its component proteins increased the proliferation and migration of hDFa and increased the expression of growth factors involved in the healing process.

Severe acute respiratory syndrome coronavirus replication inhibitor that interferes with the nucleic acid unwinding of the viral helicase.

PubMed

Adedeji, Adeyemi O; Singh, Kamalendra; Calcaterra, Nicholas E; DeDiego, Marta L; Enjuanes, Luis; Weiss, Susan; Sarafianos, Stefan G

2012-09-01

Severe acute respiratory syndrome (SARS) is a highly contagious disease, caused by SARS coronavirus (SARS-CoV), for which there are no approved treatments. We report the discovery of a potent inhibitor of SARS-CoV that blocks replication by inhibiting the unwinding activity of the SARS-CoV helicase (nsp13). We used a Förster resonance energy transfer (FRET)-based helicase assay to screen the Maybridge Hitfinder chemical library. We identified and validated a compound (SSYA10-001) that specifically blocks the double-stranded RNA (dsRNA) and dsDNA unwinding activities of nsp13, with 50% inhibitory concentrations (IC(50)s) of 5.70 and 5.30 μM, respectively. This compound also has inhibitory activity (50% effective concentration [EC(50)] = 8.95 μM) in a SARS-CoV replicon assay, with low cytotoxicity (50% cytotoxic concentration [CC(50)] = >250 μM), suggesting that the helicase plays a still unidentified critical role in the SARS-CoV life cycle. Enzyme kinetic studies on the mechanism of nsp13 inhibition revealed that SSYA10-001 acts as a noncompetitive inhibitor of nsp13 with respect to nucleic acid and ATP substrates. Moreover, SSYA10-001 does not affect ATP hydrolysis or nsp13 binding to the nucleic acid substrate. SSYA10-001 did not inhibit hepatitis C virus (HCV) helicase, other bacterial and viral RNA-dependent RNA polymerases, or reverse transcriptase. These results suggest that SSYA10-001 specifically blocks nsp13 through a novel mechanism and is less likely to interfere with the functions of cellular enzymes that process nucleic acids or ATP. Hence, it is possible that SSYA10-001 inhibits unwinding by nsp13 by affecting conformational changes during the course of the reaction or translocation on the nucleic acid. SSYA10-001 will be a valuable tool for studying the specific role of nsp13 in the SARS-CoV life cycle, which could be a model for other nidoviruses and also a candidate for further development as a SARS antiviral target.

Lentin, a novel and potent antifungal protein from shitake mushroom with inhibitory effects on activity of human immunodeficiency virus-1 reverse transcriptase and proliferation of leukemia cells.

PubMed

Ngai, Patrick H K; Ng, T B

2003-11-14

From the fruiting bodies of the edible mushroom Lentinus edodes, a novel protein designated lentin with potent antifungal activity was isolated. Lentin was unadsorbed on DEAE-cellulose, and adsorbed on Affi-gel blue gel and Mono S. The N-terminal sequence of lentin manifested similarity to endoglucanase. Lentin, which had a molecular mass of 27.5 kDa, inhibited mycelial growth in a variety of fungal species including Physalospora piricola, Botrytis cinerea and Mycosphaerella arachidicola. Lentin also exerted an inhibitory activity on HIV-1 reverse transcriptase and proliferation of leukemia cells.

HIV Resistance Prediction to Reverse Transcriptase Inhibitors: Focus on Open Data.

PubMed

Tarasova, Olga; Poroikov, Vladimir

2018-04-19

Research and development of new antiretroviral agents are in great demand due to issues with safety and efficacy of the antiretroviral drugs. HIV reverse transcriptase (RT) is an important target for HIV treatment. RT inhibitors targeting early stages of the virus-host interaction are of great interest for researchers. There are a lot of clinical and biochemical data on relationships between the occurring of the single point mutations and their combinations in the pol gene of HIV and resistance of the particular variants of HIV to nucleoside and non-nucleoside reverse transcriptase inhibitors. The experimental data stored in the databases of HIV sequences can be used for development of methods that are able to predict HIV resistance based on amino acid or nucleotide sequences. The data on HIV sequences resistance can be further used for (1) development of new antiretroviral agents with high potential for HIV inhibition and elimination and (2) optimization of antiretroviral therapy. In our communication, we focus on the data on the RT sequences and HIV resistance, which are available on the Internet. The experimental methods, which are applied to produce the data on HIV-1 resistance, the known data on their concordance, are also discussed.

Chemical system biology based molecular interactions to identify inhibitors against Q151M mutant of HIV-1 reverse transcriptase.

PubMed

Pandey, Rajan Kumar; Sharma, Drista; Ojha, Rupal; Bhatt, Tarun Kumar; Prajapati, Vijay Kumar

2018-05-09

The emergence of mutations leading to drug resistance is the main cause of therapeutic failure in the human HIV infection. Chemical system biology approach has drawn great attention to discover new antiretroviral hits with high efficacy and negligible toxicity, which can be used as a prerequisite for HIV drug resistance global action plan 2017-21. To discover potential hits, we docked 49 antiretroviral analogs (n = 6294) against HIV-1 reverse transcriptase Q151M mutant & its wild-type form and narrow downed their number in three sequential modes of docking using Schrödinger suite. Later on, 80 ligands having better docking score than reference ligands (tenofovir and lamivudine) were screened for ADME, toxicity prediction, and binding energy estimation. Simultaneously, the area under the curve (AUC) was estimated using receiver operating characteristics (ROC) curve analysis to validate docking protocols. Finally, single point energy and molecular dynamics simulation approaches were performed for best two ligands (L3 and L14). This study reveals the antiretroviral efficacy of obtained two best ligands and delivers the hits against HIV-1 reverse transcriptase Q151M mutant. Copyright © 2018 Elsevier B.V. All rights reserved.

Antitumor effect of combination of the inhibitors of two new oncotargets: proton pumps and reverse transcriptase.

PubMed

Lugini, Luana; Sciamanna, Ilaria; Federici, Cristina; Iessi, Elisabetta; Spugnini, Enrico Pierluigi; Fais, Stefano

2017-01-17

Tumor therapy needs new approaches in order to improve efficacy and reduce toxicity of the current treatments. The acidic microenvironment and the expression of high levels of endogenous non-telomerase reverse transcriptase (RT) are common features of malignant tumor cells. The anti-acidic proton pump inhibitor Lansoprazole (LAN) and the non-nucleoside RT inhibitor Efavirenz (EFV) have shown independent antitumor efficacy. LAN has shown to counteract drug tumor resistance. We tested the hypothesis that combination of LAN and EFV may improve the overall antitumor effects. We thus pretreated human metastatic melanoma cells with LAN and then with EFV, both in 2D and 3D spheroid models. We evaluated the treatment effect by proliferation and cell death/apoptosis assays in classical and in pulse administration experiments. The action of EFV was negatively affected by the tumor microenvironmental acidity, and LAN pretreatment overcame the problem. LAN potentiated the cytotoxicity of EFV to melanoma cells and, when administered during the drug interruption period, prevented the replacement of tumor cell growth.This study supports the implementation of the current therapies with combination of Proton Pumps and Reverse Transcriptase inhibitors.

Antitumor effect of combination of the inhibitors of two new oncotargets: proton pumps and reverse transcriptase

PubMed Central

Lugini, Luana; Sciamanna, Ilaria; Federici, Cristina; Iessi, Elisabetta; Spugnini, Enrico Pierluigi; Fais, Stefano

2017-01-01

Tumor therapy needs new approaches in order to improve efficacy and reduce toxicity of the current treatments. The acidic microenvironment and the expression of high levels of endogenous non-telomerase reverse transcriptase (RT) are common features of malignant tumor cells. The anti-acidic proton pump inhibitor Lansoprazole (LAN) and the non-nucleoside RT inhibitor Efavirenz (EFV) have shown independent antitumor efficacy. LAN has shown to counteract drug tumor resistance. We tested the hypothesis that combination of LAN and EFV may improve the overall antitumor effects. We thus pretreated human metastatic melanoma cells with LAN and then with EFV, both in 2D and 3D spheroid models. We evaluated the treatment effect by proliferation and cell death/apoptosis assays in classical and in pulse administration experiments. The action of EFV was negatively affected by the tumor microenvironmental acidity, and LAN pretreatment overcame the problem. LAN potentiated the cytotoxicity of EFV to melanoma cells and, when administered during the drug interruption period, prevented the replacement of tumor cell growth. This study supports the implementation of the current therapies with combination of Proton Pumps and Reverse Transcriptase inhibitors. PMID:27926505

An integrated target sequence and signal amplification assay, reverse transcriptase-PCR-enzyme-linked immunosorbent assay, to detect and characterize flaviviruses.

PubMed Central

Chang, G J; Trent, D W; Vorndam, A V; Vergne, E; Kinney, R M; Mitchell, C J

1994-01-01

We previously described a reverse transcriptase-PCR using flavivirus genus-conserved and virus species-specific amplimers (D. W. Trent and G. J. Chang, p. 355-371, in Y. Becker and C. Darai; ed., Frontiers of Virology, vol. 1, 1992). Target amplification was improved by redesigning the amplimers, and a sensitive enzyme-linked immunosorbent assay (ELISA) technique has been developed to detect amplified digoxigenin (DIG)-modified DNA. A single biotin motif and multiple DIG motifs were incorporated into each amplicon, which permitted amplicon capture by a biotin-streptavidin interaction and detection with DIG-specific antiserum in a colorimetric ELISA. We evaluated the utility of this assay for detecting St. Louis encephalitis (SLE) viral RNA in infected mosquitoes and dengue viral RNA in human serum specimens. The reverse transcriptase-PCR-ELISA was as sensitive as isolation of SLE virus by cell culture in detecting SLE viral RNA in infected mosquitoes. The test was 89% specific and 95 to 100% sensitive for identification of dengue viral RNA in serum specimens compared with isolation of virus by Aedes albopictus C6/36 cell culture and identification by the indirect immunofluorescence assay. PMID:7512096

Chemical crosslinking of the subunits of HIV-1 reverse transcriptase.

PubMed Central

Debyser, Z.; De Clercq, E.

1996-01-01

The reverse transcriptase (RT) of the human immunodeficiency virus type 1 (HIV-1) is composed of two subunits of 66 and 51 kDa in a 1 to 1 ratio. Because dimerization is a prerequisite for enzymatic activity, interference with the dimerization process could constitute an alternative antiviral strategy for RT inhibition. Here we describe an in vitro assay for the study of the dimerization state of HIV-1 reverse transcriptase based on chemical crosslinking of the subunits with dimethylsuberimidate. Crosslinking results in the formation of covalent bonds between the subunits, so that the crosslinked species can be resolved by denaturing gel electrophoresis. Crosslinked RT species with molecular weight greater than that of the dimeric form accumulate during a 1-15-min time course. Initial evidence suggests that those high molecular weight species represent trimers and tetramers and may be the result of intramolecular crosslinking of the subunits of a higher-order RT oligomer. A peptide that corresponds to part of the tryptophan repeat motif in the connection domain of HIV-1 RT inhibits crosslink formation as well as enzymatic activity. The crosslinking assay thus allows the investigation of the effect of inhibitors on the dimerization of HIV-1 RT. PMID:8745406

An integrated target sequence and signal amplification assay, reverse transcriptase-PCR-enzyme-linked immunosorbent assay, to detect and characterize flaviviruses.

PubMed

Chang, G J; Trent, D W; Vorndam, A V; Vergne, E; Kinney, R M; Mitchell, C J

1994-02-01

We previously described a reverse transcriptase-PCR using flavivirus genus-conserved and virus species-specific amplimers (D. W. Trent and G. J. Chang, p. 355-371, in Y. Becker and C. Darai; ed., Frontiers of Virology, vol. 1, 1992). Target amplification was improved by redesigning the amplimers, and a sensitive enzyme-linked immunosorbent assay (ELISA) technique has been developed to detect amplified digoxigenin (DIG)-modified DNA. A single biotin motif and multiple DIG motifs were incorporated into each amplicon, which permitted amplicon capture by a biotin-streptavidin interaction and detection with DIG-specific antiserum in a colorimetric ELISA. We evaluated the utility of this assay for detecting St. Louis encephalitis (SLE) viral RNA in infected mosquitoes and dengue viral RNA in human serum specimens. The reverse transcriptase-PCR-ELISA was as sensitive as isolation of SLE virus by cell culture in detecting SLE viral RNA in infected mosquitoes. The test was 89% specific and 95 to 100% sensitive for identification of dengue viral RNA in serum specimens compared with isolation of virus by Aedes albopictus C6/36 cell culture and identification by the indirect immunofluorescence assay.

Do non-nucleoside reverse transcriptase inhibitors contribute to lipodystrophy?

PubMed

Nolan, David

2005-01-01

Lipodystrophy complications, including lipoatrophy (pathological fat loss) and metabolic complications, have emerged as important long-term toxicities associated with antiretroviral therapy in the current era. The wealth of data that has accumulated over the past 6 years has now clarified the contribution of specific antiretroviral drugs to the risk of these clinical endpoints, with evidence that lipoatrophy is strongly associated with the choice of nucleoside reverse transcriptase inhibitor therapy (specifically, stavudine and to a lesser extent zidovudine). The aetiological basis of metabolic complications of antiretroviral therapy has proven to be complex, in that the risk appears to be modulated by a number of lifestyle factors that have made the metabolic syndrome highly prevalent in the general population, with additional contributions from HIV disease status itself, as well as from individual drugs within the HIV protease inhibitor class. The currently licensed non-nucleoside reverse transcriptase inhibitor (NNRTI) drugs, efavirenz and nevirapine, have been proven to have a favourable safety profile in terms of lipodystrophy complications. However, it must be noted that NNRTI drugs also have individual toxicity profiles that must be accounted for when considering and/or monitoring their use in the treatment of HIV infection.

Prevalence of HIV-1 Subtypes and Drug Resistance-Associated Mutations in HIV-1-Positive Treatment-Naive Pregnant Women in Pointe Noire, Republic of the Congo (Kento-Mwana Project).

PubMed

Bruzzone, Bianca; Saladini, Francesco; Sticchi, Laura; Mayinda Mboungou, Franc A; Barresi, Renata; Caligiuri, Patrizia; Calzi, Anna; Zazzi, Maurizio; Icardi, Giancarlo; Viscoli, Claudio; Bisio, Francesca

2015-08-01

The Kento-Mwana project was carried out in Pointe Noire, Republic of the Congo, to prevent mother-to-child HIV-1 transmission. To determine the prevalence of different subtypes and transmitted drug resistance-associated mutations, 95 plasma samples were collected at baseline from HIV-1-positive naive pregnant women enrolled in the project during the years 2005-2008. Full protease and partial reverse transcriptase sequencing was performed and 68/95 (71.6%) samples were successfully sequenced. Major mutations to nucleoside reverse transcriptase inhibitors, nonnucleoside reverse transcriptase inhibitors, and protease inhibitors were detected in 4/68 (5.9%), 3/68 (4.4%), and 2/68 (2.9%) samples, respectively. Phylogenetic analysis of HIV-1 isolates showed a high prevalence of unique recombinant forms (24/68, 35%), followed by CRF45_cpx (7/68, 10.3%) and subsubtype A3 and subtype G (6/68 each, 8.8%). Although the prevalence of transmitted drug resistance mutations appears to be currently limited, baseline HIV-1 genotyping is highly advisable in conjunction with antiretroviral therapy scale-up in resource-limited settings to optimize treatment and prevent perinatal transmission.

Copper (II) and zinc (II) complexes with flavanone derivatives: Identification of potential cholinesterase inhibitors by on-flow assays.

PubMed

Sarria, André Lucio Franceschini; Vilela, Adriana Ferreira Lopes; Frugeri, Bárbara Mammana; Fernandes, João Batista; Carlos, Rose Maria; da Silva, Maria Fátima das Graças Fernandes; Cass, Quezia Bezerra; Cardoso, Carmen Lúcia

2016-11-01

Metal chelates strongly influence the nature and magnitude of pharmacological activities in flavonoids. In recent years, studies have shown that a promising class of flavanone-metal ion complexes can act as selective cholinesterase inhibitors (ChEIs), which has led our group to synthesize a new series of flavanone derivatives (hesperidin, hesperetin, naringin, and naringenin) complexed to either copper (II) or zinc (II) and to evaluate their potential use as selective ChEIs. Most of the synthesized complexes exhibited greater inhibitory activity against acetylcholinesterase (AChE) than against butyrylcholinesterase (BChE). Nine of these complexes constituted potent, reversible, and selective ChEIs with inhibitory potency (IC 50 ) and inhibitory constant (K i ) ranging from 0.02 to 4.5μM. Copper complexes with flavanone-bipyridine derivatives afforded the best inhibitory activity against AChE and BChE. The complex Cu(naringin)(2,2'-bipyridine) (11) gave IC 50 and K i values of 0.012±0.002 and 0.07±0.01μM for huAChE, respectively, which were lower than the inhibitory values obtained for standard galanthamine (IC 50 =206±30.0 and K i =126±18.0μM). Evaluation of the inhibitory activity of this complex against butyrylcholinesterase from human serum (huBChE) gave IC 50 and K i values of 8.0±1.4 and 2.0±0.1μM, respectively. A Liquid Chromatography-Immobilized Capillary Enzyme Reactor by UV detection (LC-ICER-UV) assay allowed us to determine the IC 50 and K i values and the type of mechanism for the best inhibitors. Copyright © 2016 Elsevier Inc. All rights reserved.

Emodin regulating excision repair cross-complementation group 1 through fibroblast growth factor receptor 2 signaling

PubMed Central

Chen, Gang; Qiu, Hong; Ke, Shan-Dong; Hu, Shao-Ming; Yu, Shi-Ying; Zou, Sheng-Quan

2013-01-01

AIM: To investigate the molecular mechanisms underlying the reversal effect of emodin on platinum resistance in hepatocellular carcinoma. METHODS: After the addition of 10 μmol/L emodin to HepG2/oxaliplatin (OXA) cells, the inhibition rate (IR), 50% inhibitory concentration (IC50) and reversal index (IC50 in experimental group/IC50 in control group) were calculated. For HepG2, HepG2/OXA, HepG2/OXA/T, each cell line was divided into a control group, OXA group, OXA + fibroblast growth factor 7 (FGF7) group and OXA + emodin group, and the final concentrations of FGF7, emodin and OXA in each group were 5 ng/mL, 10 μg/mL and 10 μmol/L, respectively. Single-cell gel electrophoresis was conducted to detect DNA damage, and the fibroblast growth factor receptor 2 (FGFR2), phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2) and excision repair cross-complementing gene 1 (ERCC1) protein expression levels in each group were examined by Western blotting. RESULTS: Compared with the IC50 of 120.78 μmol/L in HepG2/OXA cells, the IC50 decreased to 39.65 μmol/L after treatment with 10 μmol/L emodin; thus, the reversal index was 3.05. Compared with the control group, the tail length and Olive tail length in the OXA group, OXA + FGF7 group and OXA + emodin group were significantly increased, and the differences were statistically significant (P < 0.01). The tail length and Olive tail length were lower in the OXA + FGF7 group than in the OXA group, and this difference was also statistically significant. Compared with the OXA + FGF7 group, the tail extent, the Olive tail moment and the percentage of tail DNA were significantly increased in the OXA + emodin group, and these differences were statistically significant (P < 0.01). In comparison with its parental cell line HepG2, the HepG2/OXA cells demonstrated significantly increased FGFR2, p-ERK1/2 and ERCC1 expression levels, whereas the expression of all three molecules was significantly inhibited in HepG2/OXA/T cells, in which FGFR2 was silenced by FGFR2 shRNA. In the examined HepG2 cells, the FGFR2, p-ERK1/2 and ERCC1 expression levels demonstrated increasing trends in the OXA group and OXA + FGF7 group. Compared with the OXA group and OXA + FGF7 group, the FGFR2, p-ERK1/2, and ERCC1 expression levels were significantly lower in the OXA + emodin group, and these differences were statistically significant. In the HepG2/OXA/T cell line that was transfected with FGFR2 shRNA, the FGFR2, p-ERK1/2 and ERCC1 expression levels were significantly inhibited, but there were no significant differences in these expression levels among the OXA, OXA + FGF7 and OXA + emodin groups. CONCLUSION: Emodin markedly reversed OXA resistance by enhancing OXA DNA damage in HepG2/OXA cells, and the molecular mechanism was related to the inhibitory effect on ERCC1 expression being mediated by the FGFR2/ERK1/2 signaling pathway. PMID:23674849

Structure-based methods to predict mutational resistance to diarylpyrimidine non-nucleoside reverse transcriptase inhibitors.

PubMed

Azeem, Syeda Maryam; Muwonge, Alecia N; Thakkar, Nehaben; Lam, Kristina W; Frey, Kathleen M

2018-01-01

Resistance to non-nucleoside reverse transcriptase inhibitors (NNRTIs) is a leading cause of HIV treatment failure. Often included in antiviral therapy, NNRTIs are chemically diverse compounds that bind an allosteric pocket of enzyme target reverse transcriptase (RT). Several new NNRTIs incorporate flexibility in order to compensate for lost interactions with amino acid conferring mutations in RT. Unfortunately, even successful inhibitors such as diarylpyrimidine (DAPY) inhibitor rilpivirine are affected by mutations in RT that confer resistance. In order to aid drug design efforts, it would be efficient and cost effective to pre-evaluate NNRTI compounds in development using a structure-based computational approach. As proof of concept, we applied a residue scan and molecular dynamics strategy using RT crystal structures to predict mutations that confer resistance to DAPYs rilpivirine, etravirine, and investigational microbicide dapivirine. Our predictive values, changes in affinity and stability, are correlative with fold-resistance data for several RT mutants. Consistent with previous studies, mutation K101P is predicted to confer high-level resistance to DAPYs. These findings were further validated using structural analysis, molecular dynamics, and an enzymatic reverse transcription assay. Our results confirm that changes in affinity and stability for mutant complexes are predictive parameters of resistance as validated by experimental and clinical data. In future work, we believe that this computational approach may be useful to predict resistance mutations for inhibitors in development. Published by Elsevier Inc.

Arylazolylthioacetanilide. Part 11: design, synthesis and biological evaluation of 1,2,4-triazole thioacetanilide derivatives as novel non-nucleoside HIV-1 reverse transcriptase inhibitors.

PubMed

Li, Zhenyu; Cao, Yuan; Zhan, Peng; Pannecouque, Christophe; Balzarini, Jan; Clercq, Erik De; Shen, Yuemao; Liu, Xinyong

2013-11-01

A series of novel 1,2,4-triazole thioacetanilide derivatives has been designed, synthesized and evaluated for their anti-HIV activities in MT-4 cells. Half of these compounds showed moderate to potent activities against wild-type HIV-1 with an EC50 ranging from 38.0 μM to 4.08 µM. Among them, 2-(4-(2-fluorobenzyl)-5-isopropyl-4H-1,2,4-triazol- 3-ylthio)-N-(2-nitrophenyl)acetamide 7d was identified as the most promising compound (EC50 = 4.26 µM, SI = 49). However, no compound was active against HIV-2. The preliminary structure-activity relationships among the newly synthesized congeners are discussed.

Isolation, nucleotide sequence and expression of a cDNA encoding feline granulocyte colony-stimulating factor.

PubMed

Dunham, S P; Onions, D E

2001-06-21

A cDNA encoding feline granulocyte colony stimulating factor (fG-CSF) was cloned from alveolar macrophages using the reverse transcriptase-polymerase chain reaction. The cDNA is 949 bp in length and encodes a predicted mature protein of 174 amino acids. Recombinant fG-CSF was expressed as a glutathione S-transferase fusion and purified by affinity chromatography. Biological activity of the recombinant protein was demonstrated using the murine myeloblastic cell line GNFS-60, which showed an ED50 for fG-CSF of approximately 2 ng/ml. Copyright 2001 Academic Press.

Maraviroc, as a Switch Option, in HIV-1-infected Individuals With Stable, Well-controlled HIV Replication and R5-tropic Virus on Their First Nucleoside/Nucleotide Reverse Transcriptase Inhibitor Plus Ritonavir-boosted Protease Inhibitor Regimen: Week 48 Results of the Randomized, Multicenter MARCH Study.

PubMed

Pett, Sarah Lilian; Amin, Janaki; Horban, Andrejz; Andrade-Villanueva, Jaime; Losso, Marcelo; Porteiro, Norma; Sierra Madero, Juan; Belloso, Waldo; Tu, Elise; Silk, David; Kelleher, Anthony; Harrigan, Richard; Clark, Andrew; Sugiura, Wataru; Wolff, Marcelo; Gill, John; Gatell, Jose; Fisher, Martin; Clarke, Amanda; Ruxrungtham, Kiat; Prazuck, Thierry; Kaiser, Rolf; Woolley, Ian; Arnaiz, Juan Alberto; Cooper, David; Rockstroh, Jürgen K; Mallon, Patrick; Emery, Sean

2016-07-01

Alternative combination antiretroviral therapies in virologically suppressed human immunodeficiency virus (HIV)-infected patients experiencing side effects and/or at ongoing risk of important comorbidities from current therapy are needed. Maraviroc (MVC), a chemokine receptor 5 antagonist, is a potential alternative component of therapy in those with R5-tropic virus. The Maraviroc Switch Study is a randomized, multicenter, 96-week, open-label switch study in HIV type 1-infected adults with R5-tropic virus, virologically suppressed on a ritonavir-boosted protease inhibitor (PI/r) plus double nucleoside/nucleotide reverse transcriptase inhibitor (2 N(t)RTI) backbone. Participants were randomized 1:2:2 to current combination antiretroviral therapy (control), or replacing the protease inhibitor (MVC + 2 N(t)RTI arm) or the nucleoside reverse transcriptase inhibitor backbone (MVC + PI/r arm) with twice-daily MVC. The primary endpoint was the difference (switch minus control) in proportion with plasma viral load (VL) <200 copies/mL at 48 weeks. The switch arms were judged noninferior if the lower limit of the 95% confidence interval (CI) for the difference in the primary endpoint was < -12% in the intention-to-treat (ITT) population. The ITT population comprised 395 participants (control, n = 82; MVC + 2 N(t)RTI, n = 156; MVC + PI/r, n = 157). Baseline characteristics were well matched. At week 48, noninferior rates of virological suppression were observed in those switching away from a PI/r (93.6% [95% CI, -9.0% to 2.2%] and 91.7% [95% CI, -9.6% to 3.8%] with VL <200 and <50 copies/mL, respectively) compared to the control arm (97.6% and 95.1% with VL <200 and <50 copies/mL, respectively). In contrast, MVC + PI/r did not meet noninferiority bounds and was significantly inferior (84.1% [95% CI, -19.8% to -5.8%] and 77.7% [95% CI, -24.9% to -8.4%] with VL <200 and <50 copies/mL, respectively) to the control arm in the ITT analysis. These data support MVC as a switch option for ritonavir-boosted PIs when partnered with a 2-N(t)RTI backbone, but not as part of N(t)RTI-sparing regimens comprising MVC with PI/r. NCT01384682. © The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.

Inhibition of HIV-1 by curcumin A, a novel curcumin analog

PubMed Central

Kumari, Namita; Kulkarni, Amol A; Lin, Xionghao; McLean, Charlee; Ammosova, Tatiana; Ivanov, Andrey; Hipolito, Maria; Nekhai, Sergei; Nwulia, Evaristus

2015-01-01

Despite the remarkable success of combination antiretroviral therapy at curtailing HIV progression, emergence of drug-resistant viruses, chronic low-grade inflammation, and adverse effects of combination antiretroviral therapy treatments, including metabolic disorders collectively present the impetus for development of newer and safer antiretroviral drugs. Curcumin, a phytochemical compound, was previously reported to have some in vitro anti-HIV and anti-inflammatory activities, but poor bioavailability has limited its clinical utility. To circumvent the bioavailability problem, we derivatized curcumin to sustain retro-aldol decomposition at physiological pH. The lead compound derived, curcumin A, showed increased stability, especially in murine serum where it was stable for up to 25 hours, as compared to curcumin that only had a half-life of 10 hours. Both curcumin and curcumin A showed similar inhibition of one round of HIV-1 infection in cultured lymphoblastoid (also called CEM) T cells (IC50=0.7 μM). But in primary peripheral blood mononuclear cells, curcumin A inhibited HIV-1 more potently (IC50=2 μM) compared to curcumin (IC50=12 μM). Analysis of specific steps of HIV-1 replication showed that curcumin A inhibited HIV-1 reverse transcription, but had no effect on HIV-1 long terminal repeat basal or Tat-induced transcription, or NF-κB-driven transcription at low concentrations that affected reverse transcription. Finally, we showed curcumin A induced expression of HO-1 and decreased cell cycle progression of T cells. Our findings thus indicate that altering the core structure of curcumin could yield more stable compounds with potent antiretroviral and anti-inflammatory activities. PMID:26366056

copia-like retrotransposons are ubiquitous among plants.

PubMed Central

Voytas, D F; Cummings, M P; Koniczny, A; Ausubel, F M; Rodermel, S R

1992-01-01

Transposable genetic elements are assumed to be a feature of all eukaryotic genomes. Their identification, however, has largely been haphazard, limited principally to organisms subjected to molecular or genetic scrutiny. We assessed the phylogenetic distribution of copia-like retrotransposons, a class of transposable element that proliferates by reverse transcription, using a polymerase chain reaction assay designed to detect copia-like element reverse transcriptase sequences. copia-like retrotransposons were identified in 64 plant species as well as the photosynthetic protist Volvox carteri. The plant species included representatives from 9 of 10 plant divisions, including bryophytes, lycopods, ferns, gymnosperms, and angiosperms. DNA sequence analysis of 29 cloned PCR products and of a maize retrotransposon cDNA confirmed the identity of these sequences as copia-like reverse transcriptase sequences, thereby demonstrating that this class of retrotransposons is a ubiquitous component of plant genomes. Images PMID:1379734

Antiviral interactions of combinations of highly potent 2,4(1H,3H)-pyrimidinedione congeners and other anti-HIV agents.

PubMed

Hartman, Tracy L; Yang, Lu; Buckheit, Robert W

2011-12-01

Structure-activity relationship evaluation of seventy-four 2,4(1H,3H)-pyrimidinedione derivatives identified seven lead compounds based on anti-HIV-1 potency, extended range of action to include HIV-2, virus entry inhibition, reverse transcriptase inhibition, and lack of cytotoxicity to human cells. The selected pyrimidinedione congeners are highly active inhibitors of HIV-1 with EC(50) values ranging from 0.6 to 2 nM in CEM-SS cells infected with laboratory derived viruses, 11-20 nM in fresh human PBMCs infected with subtype B (HT/92/599) virus, and 2-7 nM in PBMCs infected with the clinical subtype C (ZA/97/003) virus. Combination antiviral assays were performed using the laboratory adapted RF strain of HIV-1 in CEM-SS cells and with a clade B and C low passage clinical isolate in fresh human peripheral mononuclear cells and the compound interactions were analyzed using MacSynergy II. The seven pyrimidinedione compounds resulted in additive to synergistic interactions in combination with entry and fusion inhibitors, nonnucleoside and nucleoside reverse transcriptase inhibitors, and the protease inhibitors. No evidence of antagonistic antiviral activity or synergistic cytotoxicity was detected with the combinations of compounds tested. The dual mechanism of action of the pyrimidinediones resulting in inhibition of both virus entry and reverse transcription suggests excellent potential of these lead pyrimidinediones as candidates for combination therapy with other approved HIV inhibitors of varying mechanism of action. Copyright © 2011. Published by Elsevier B.V.

Leishmanicidal and reversal multidrug resistance constituents from Aeonium lindleyi.

PubMed

Kennedy, María L; Cortés, Fernando; Piñero, José E; Castanys, Santiago; López-Arencibia, Atteneri; Gamarro, Francisco; Bazzocchi, Isabel L; Jiménez, Ignacio A

2011-01-01

A new bicyclic diterpene with a labdane skeleton, 7-oxo-labd-8-en-15-ol ( 1), along with two known diterpenes and ten flavonoids were isolated from the leaves of Aeonium lindleyi (Crassulaceae). Their structures were elucidated on the basis of spectroscopic data, including 1D and 2D NMR experiments, and comparison with spectroscopic data reported in the literature. Labdan-8 α,15-diol (2) and labd-8(17)-en-3 β,15-diol (3) showed leishmanicidal activity against Leishmania tropica (IC (50) = 77.0 µM) and Leishmania braziliensis (IC (50) = 68.0 µM) similar to ketoconazole used as positive control. 5,3'-Dihydroxy-3,7,4',5'-tetramethoxyflavone (8) and combretol (9) showed moderate activity (growth inhibition 87.3 and 73.0 %, respectively, at 50 µM) against a multidrug-resistant L. tropica line. © Georg Thieme Verlag KG Stuttgart · New York.

Dolutegravir Plus Two Nucleoside Reverse Transcriptase Inhibitors versus Efavirenz Plus Two Nucleoside Reverse Transcriptase Inhibitors As Initial Antiretroviral Therapy for People with HIV: A Systematic Review.

PubMed

Rutherford, George W; Horvath, Hacsi

2016-01-01

Dolutegravir (DTG) is a once-daily unboosted second-generation integrase-inhibitor that along with two nucleoside reverse transcriptase inhibitors is one of several regimens recommended by the United States, United Kingdom and European Union for first-line antiretroviral treatment of people with HIV infection. Our objective was to review the evidence for the efficacy and safety of DTG-based first-line regimens compared to efavirenz (EFV)-based regimens. We conducted a systematic review. We comprehensively searched a range of databases as well as conference abstracts and a trials registry. We used Cochrane methods in screening and data collection and assessed each study's risk of bias with the Cochrane tool. We meta-analyzed data using a fixed-effects model. We used GRADE to assess evidence quality. From 492 search results, we identified two randomized controlled trials, reported in five peer-reviewed articles and one conference abstract. One trial tested two DTG-based regimens (DTG + abacavir (ABC) + lamivudine (3TC) or DTG + tenofovir + emtricitabine) against an EFV-based regimen (EFV+ ABC+3TC). The other trial tested DTG+ABC+3TC against EFV+ABC+3TC. In meta-analysis, DTG-containing regimens were superior to EFV-containing regimens at 48 weeks and at 96 weeks (RR = 1.10, 95% CI 1.04-1.16; and RR = 1.12, 95% CI 1.04-1.21, respectively). In one trial, the DTG-containing regimen was superior at 144 weeks (RR = 1.13, 95% CI 1.02-1.24). DTG-containing regimens were superior in reducing treatment discontinuation compared to those containing EFV at 96 weeks and at 144 weeks (RR = 0.27, 95% CI 0.15-0.50; and RR = 0.28, 95% CI 0.16-0.48, respectively). Risk of serious adverse events was similar in each regimen at 96 weeks (RR = 1.15, 95% CI 0.80-1.63) and 144 weeks (RR = 0.93, 95% CI 0.68-1.29). Risk of bias was moderate overall, as was GRADE evidence quality. DTG-based regimens should be considered in future World Health Organization guidelines for initial HIV treatment.

Purification and Characterization of a Lectin from Green Split Peas (Pisum sativum).

PubMed

Ng, Tzi Bun; Chan, Yau Sang; Ng, Charlene Cheuk Wing; Wong, Jack Ho

2015-11-01

Lectins have captured the attention of a large number of researchers on account of their various exploitable activities, including antitumor, immunomodulatory, antifungal, as well as HIV reverse transcriptase inhibitory activities. A mannose/glucose-specific lectin was isolated from green split peas (a variety of Pisum sativum) and characterized. The purification step involved anion-exchange chromatography on a DEAE-cellulose column, cation-exchange chromatography on an SP-Sepharose column, and gel filtration by fast protein liquid chromatography (FPLC) on Superdex 200. The purified lectin had a native molecular mass of around 50 kDa as determined by size exclusion chromatography. It appeared as a heterotetramer, composed of two distinct polypeptide bands with a molecular mass of 6 and 19 kDa, respectively, in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The N-terminal sequence of green split pea lectin shows some degree of homology compared to lectins from other legume species. Its hemagglutinating activity was inhibited by glucose, mannose, and sucrose, and attenuated at pH values higher than 12 or lower than 3. Hemagglutinating activity was preserved at temperatures lower than 80 °C. The lectin did not show antifungal activity toward fungi including Fusarium oxysporum, Botrytis cinerea, and Mycosphaerella arachidicola. Green split pea lectin showed a mitogenic effect toward murine splenocytes and could inhibit the activity of HIV-1 reverse transcriptase.

Endogenous New World primate type C viruses isolated from owl monkey (Aotus trivirgatus) kidney cell line.

PubMed Central

Todaro, G J; Sherr, C J; Sen, A; King, N; Daniel, M D; Fleckenstein, B

1978-01-01

A type C virus (OMC-1) detected in a culture of owl monkey kidney cells resembled typical type C viruses morphologically, but was slightly larger than previously characterized mammalian type C viruses. OMC-1 can be transmitted to bat lung cells and cat embryo fibroblasts. The virions band at a density of 1.16 g/ml in isopycnic sucrose density gradients and contain reverse transcriptase and a 60-65S RNA genome composed of approximately 32S subunits. The reverse transcriptase is immunologically and biochemically distinct from the polymerases of othe retroviruses. Radioimmunoassays directed to the interspecies antigenic determinants of the major structure proteins of other type C viruses do not detect a related antigen in OMC-1. Nucleic acid hybridization experiments using labeled viral genomic RNA or proviral cDNA transcripts to normal cellular DNA of different species show that OMC-1 is an endogenous virus with multiple virogene copies (20-50 per haploid genome) present in normal owl monkey cells and is distinct from previously isolated type C and D viruses. Sequences related to the OMC-1 genome can be detected in other New World monkeys. Thus, similar to the Old World primates (e.g., baboons as a prototype), the New World monkeys contain endogenous type C viral genes that appear to have been transmitted in the primate germ line. Images PMID:76312

[Thyroid dysfunction in adults infected by human immunodeficiency virus].

PubMed

Abelleira, Erika; De Cross, Graciela A; Pitoia, Fabián

2014-01-01

Patients infected with human immunodeficiency virus (HIV) have a higher prevalence of thyroid dysfunction when compared with the general population. The most frequently observed manifestations are euthyroid sick syndrome, Graves' disease and subclinical hypothyroidism. The relationship between the use of highly active antiretroviral therapy and the increased prevalence of thyroid dysfunction has been demonstrated in several series of patients. Grave's disease is recognized as a consequence of immune restitution syndrome. Besides, several studies have suggested an association between hypothyroidism and the use of nucleoside reverse transcriptase inhibitors, particularly stavudine and non-nucleoside reverse transcriptase inhibitors such as efavirenz. Further studies could provide additional evidence of the need for routine assessment of thyroid function in HIV-infected patients.

In search of a treatment for HIV--current therapies and the role of non-nucleoside reverse transcriptase inhibitors (NNRTIs).

PubMed

Reynolds, Chevonne; de Koning, Charles B; Pelly, Stephen C; van Otterlo, Willem A L; Bode, Moira L

2012-07-07

The human immunodeficiency virus (HIV) causes AIDS (acquired immune deficiency syndrome), a disease in which the immune system progressively deteriorates, making sufferers vulnerable to all manner of opportunistic infections. Currently, world-wide there are estimated to be 34 million people living with HIV, with the vast majority of these living in sub-Saharan Africa. Therefore, an important research focus is development of new drugs that can be used in the treatment of HIV/AIDS. This review gives an overview of the disease and addresses the drugs currently used for treatment, with specific emphasis on new developments within the class of allosteric non-nucleoside reverse transcriptase inhibitors (NNRTIs).

Hsp90 is required for the activity of a hepatitis B virus reverse transcriptase.

PubMed Central

Hu, J; Seeger, C

1996-01-01

The heat shock protein Hsp90 is known as an essential component of several signal transduction pathways and has now been identified as an essential host factor for hepatitis B virus replication. Hsp90 interacts with the viral reverse transcriptase to facilitate the formation of a ribonucleoprotein (RNP) complex between the polymerase and an RNA ligand. This RNP complex is required early in replication for viral assembly and initiation of DNA synthesis through a protein-priming mechanism. These results thus invoke a role for the Hsp90 pathway in the formation of an RNP. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 PMID:8577714

In Vitro Cross-Resistance Profiles of Rilpivirine, Dapivirine, and MIV-150, Nonnucleoside Reverse Transcriptase Inhibitor Microbicides in Clinical Development for the Prevention of HIV-1 Infection

PubMed Central

Giacobbi, Nicholas S.

2017-01-01

ABSTRACT Rilpivirine (RPV), dapivirine (DPV), and MIV-150 are in development as microbicides. It is not known whether they will block infection of circulating nonnucleoside reverse transcriptase inhibitor (NNRTI)-resistant human immunodeficiency virus type 1 (HIV-1) variants. Here, we demonstrate that the activity of DPV and MIV-150 is compromised by many resistant viruses containing single or double substitutions. High DPV genital tract concentrations from DPV ring use may block replication of resistant viruses. However, MIV-150 genital tract concentrations may be insufficient to inhibit many resistant viruses, including those harboring K103N or Y181C. PMID:28507107

The MONET trial: week 144 analysis of the efficacy of darunavir/ritonavir (DRV/r) monotherapy versus DRV/r plus two nucleoside reverse transcriptase inhibitors, for patients with viral load < 50 HIV-1 RNA copies/mL at baseline.

PubMed

Arribas, J R; Clumeck, N; Nelson, M; Hill, A; van Delft, Y; Moecklinghoff, C

2012-08-01

In the MONotherapy in Europe with Tmc114 (MONET) trial, darunavir/ritonavir (DRV/r) monotherapy showed noninferior efficacy vs. two nucleoside reverse transcriptase inhibitors (NRTIs) plus DRV/r at the primary 48-week analysis. The trial was continued to week 144 to assess the durability of the results. A total of 256 patients with viral load < 50 HIV-1 RNA copies/mL on current highly active antiretroviral therapy (HAART) for at least 6 months switched to DRV/r 800/100 mg once daily, either as monotherapy (n=127) or with two NRTIs (n=129). Treatment failure was defined as two consecutive HIV RNA levels above 50 copies/mL [time to loss of virological response (TLOVR)] by week 144, or discontinuation of study drugs. Eighty-one per cent of patients were male and 91% were Caucasian, and they had a median baseline CD4 count of 575 cells/uL. More patients in the DRV/r monotherapy arm had hepatitis C virus coinfection at baseline than in the control arm (18% vs. 12%, respectively). By week 144, the percentage of patients with HIV RNA < 50 copies/mL [intent to treat (ITT), TLOVR, switch=failure method] was 69% vs. 75% in the DRV/r monotherapy and triple therapy arms [difference= -5.9%; 95% confidence interval (CI) -16.9%, +5.1%]; by a strict ITT analysis (switches not considered failures), the percentage of patients with HIV RNA < 50 copies/mL was 84% vs. 83.5%, respectively (difference= +0.5%; 95% CI -8.7%, +9.7%). Twenty-one and 13 patients had two consecutive HIV RNA results above 50 copies/mL in the DRV/r monotherapy arm and triple therapy arm, respectively, of whom 18 of 21 (86%) and 10 of 13 (77%) had HIV RNA < 50 copies/mL at week 144. In this study, for patients with HIV RNA < 50 copies/mL at baseline, switching to DRV/r monotherapy showed noninferior efficacy to DRV/r plus two NRTIs in a strict ITT (switches not considered failures) analysis, but not in a TLOVR switch equals failure analysis. © 2012 British HIV Association.

Design and performance of the CDC real-time reverse transcriptase PCR swine flu panel for detection of 2009 A (H1N1) pandemic influenza virus.

PubMed

Shu, Bo; Wu, Kai-Hui; Emery, Shannon; Villanueva, Julie; Johnson, Roy; Guthrie, Erica; Berman, LaShondra; Warnes, Christine; Barnes, Nathelia; Klimov, Alexander; Lindstrom, Stephen

2011-07-01

Swine influenza viruses (SIV) have been shown to sporadically infect humans and are infrequently identified by the Influenza Division of the Centers for Disease Control and Prevention (CDC) after being received as unsubtypeable influenza A virus samples. Real-time reverse transcriptase PCR (rRT-PCR) procedures for detection and characterization of North American lineage (N. Am) SIV were developed and implemented at CDC for rapid identification of specimens from cases of suspected infections with SIV. These procedures were utilized in April 2009 for detection of human cases of 2009 A (H1N1) pandemic (pdm) influenza virus infection. Based on genetic sequence data derived from the first two viruses investigated, the previously developed rRT-PCR procedures were optimized to create the CDC rRT-PCR Swine Flu Panel for detection of the 2009 A (H1N1) pdm influenza virus. The analytical sensitivity of the CDC rRT-PCR Swine Flu Panel was shown to be 5 copies of RNA per reaction and 10(-1.3 - -0.7) 50% infectious doses (ID(50)) per reaction for cultured viruses. Cross-reactivity was not observed when testing human clinical specimens or cultured viruses that were positive for human seasonal A (H1N1, H3N2) and B influenza viruses. The CDC rRT-PCR Swine Flu Panel was distributed to public health laboratories in the United States and internationally from April 2009 until June 2010. The CDC rRT-PCR Swine Flu Panel served as an effective tool for timely and specific detection of 2009 A (H1N1) pdm influenza viruses and facilitated subsequent public health response implementation.

Effect of dolutegravir in combination with Nucleoside Reverse Transcriptase Inhibitors (NRTIs) on people living with HIV who have pre-existing NRTI mutations.

PubMed

Sörstedt, Erik; Carlander, Christina; Flamholc, Leo; Hejdeman, Bo; Svedhem, Veronica; Sönnerborg, Anders; Gisslén, Magnus; Yilmaz, Aylin

2018-05-01

Until the introduction of dolutegravir (DTG), people living with HIV (PLWH) who have developed nucleoside reverse transcriptase inhibitor (NRTI) mutations have had few other treatment options outside of regimens based on ritonavir-boosted protease inhibitors (PI/r). Here we report treatment results among PLWH in Sweden with pre-existing NRTI mutations on antiretroviral treatment (ART) with DTG and one to two NRTIs. All PLWH on ART with DTG and one to two NRTIs with pre-existing NRTI mutations were retrospectively identified from the National InfCare HIV database. As controls, PLWH on PI/r and one to two NRTIs, matched according to Genotypic Susceptibility Score and observation time, were included. Data were collected as long as the study population was on treatment with DTG; controls were monitored for the same interval. Outcome was classified as either treatment success or failure. In total, 244 participants (122 individuals treated with DTG and 122 individuals treated with PI/r) were included. Median observation time was 78 weeks (interquartile range 50-98 weeks) for participants on DTG and 75 weeks (50-101 weeks) for individuals on PI/r. Viral failure was detected in four individuals treated with DTG and three individuals treated with PI/r, resulting in similar success rates of 96.7% and 97.5%, respectively. No new mutations were found among participants with treatment failure. DTG in combination with one to two NRTIs was as efficient as PI/r in individuals with pre-existing NRTI mutations in this setting. It may be considered an alternative to PI/r-based ART even in the presence of NRTI resistance. Copyright © 2018 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

Design and Performance of the CDC Real-Time Reverse Transcriptase PCR Swine Flu Panel for Detection of 2009 A (H1N1) Pandemic Influenza Virus▿†‡

PubMed Central

Shu, Bo; Wu, Kai-Hui; Emery, Shannon; Villanueva, Julie; Johnson, Roy; Guthrie, Erica; Berman, LaShondra; Warnes, Christine; Barnes, Nathelia; Klimov, Alexander; Lindstrom, Stephen

2011-01-01

Swine influenza viruses (SIV) have been shown to sporadically infect humans and are infrequently identified by the Influenza Division of the Centers for Disease Control and Prevention (CDC) after being received as unsubtypeable influenza A virus samples. Real-time reverse transcriptase PCR (rRT-PCR) procedures for detection and characterization of North American lineage (N. Am) SIV were developed and implemented at CDC for rapid identification of specimens from cases of suspected infections with SIV. These procedures were utilized in April 2009 for detection of human cases of 2009 A (H1N1) pandemic (pdm) influenza virus infection. Based on genetic sequence data derived from the first two viruses investigated, the previously developed rRT-PCR procedures were optimized to create the CDC rRT-PCR Swine Flu Panel for detection of the 2009 A (H1N1) pdm influenza virus. The analytical sensitivity of the CDC rRT-PCR Swine Flu Panel was shown to be 5 copies of RNA per reaction and 10−1.3∼−0.7 50% infectious doses (ID50) per reaction for cultured viruses. Cross-reactivity was not observed when testing human clinical specimens or cultured viruses that were positive for human seasonal A (H1N1, H3N2) and B influenza viruses. The CDC rRT-PCR Swine Flu Panel was distributed to public health laboratories in the United States and internationally from April 2009 until June 2010. The CDC rRT-PCR Swine Flu Panel served as an effective tool for timely and specific detection of 2009 A (H1N1) pdm influenza viruses and facilitated subsequent public health response implementation. PMID:21593260

Functional analysis of the interactions between reovirus particles and various proteases in vitro

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sargent, M.D.; Long, D.G.; Borsa, J.

1977-01-01

The digestion of purified reovirus particles by various proteases including chymotrypsin, trypsin, pronase, papain, bromelain, proteinase K, and fibrinolysin has been examined as it relates to virion transcriptase activation and alteration of infectivity. In every case uncoating to the level of active transcriptase proceeds via two mechanistically distinct steps. All the proteases tested serve to mediate only the first of the two steps, converting intact virions to intermediate subviral particles (ISVP) in which the transcriptase is retained in a latent state. The second step of the uncoating process is mediated by a K/sup +/ ion-triggered, endogenous mechanism and results inmore » conversion of ISVP to cores, concomitant with transcriptase activation and loss of infectivity. All of the tested enzymes, except trypsin, reversibly block the second step of uncoating. These results indicate the generality, with respect to protease employed, of the two-step process for reovirus uncoating and transcriptase activation demonstrated previously with chymotrypsin.« less

An integrated molecular dynamics, principal component analysis and residue interaction network approach reveals the impact of M184V mutation on HIV reverse transcriptase resistance to lamivudine.

PubMed

Bhakat, Soumendranath; Martin, Alberto J M; Soliman, Mahmoud E S

2014-08-01

The emergence of different drug resistant strains of HIV-1 reverse transcriptase (HIV RT) remains of prime interest in relation to viral pathogenesis as well as drug development. Amongst those mutations, M184V was found to cause a complete loss of ligand fitness. In this study, we report the first account of the molecular impact of M184V mutation on HIV RT resistance to 3TC (lamivudine) using an integrated computational approach. This involved molecular dynamics simulation, binding free energy analysis, principle component analysis (PCA) and residue interaction networks (RINs). Results clearly confirmed that M184V mutation leads to steric conflict between 3TC and the beta branched side chain of valine, decreases the ligand (3TC) binding affinity by ∼7 kcal mol(-1) when compared to the wild type, changes the overall conformational landscape of the protein and distorts the native enzyme residue-residue interaction network. The comprehensive molecular insight gained from this study should be of great importance in understanding drug resistance against HIV RT as well as assisting in the design of novel reverse transcriptase inhibitors with high ligand efficacy on resistant strains.

Dipyridodiazepinone analogs as human immunodeficiency virus type 1-specific non-nucleoside reverse transcriptase inhibitors: an overview.

PubMed

Lv, M; Xu, H

2010-01-01

According to World Health Organization (WHO)/Joint United Nations Programme on human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) (UNAIDS) Report in 2007, 33.2 million people are living with HIV, 2.5 million ones have been newly infected with HIV, and 2.1 million ones died from AIDS, including 330,000 children. Therefore, HIV/AIDS still remains a public health emergency and a leading cause of mortality worldwide. It is believed that reverse transcriptase (RT) is a crucial enzyme in the life cycle of HIV-1, and thereby RT has been the important drug target for antiretroviral (ARV) chemotherapy against AIDS. To our knowledge, dipyridodiazepinone analogs have been considered as one class of potential non-nucleoside reverse transcriptase inhibitors (NNRTIs), especially the structurally and chemically related nevirapine (Viramune(R)), which was the first NNRTI approved by the U. S. Food and Drug Administration (FDA) for the treatment of HIV-1 infection for adults in 1996 and for children in 1998. This review mainly highlights the progress of synthesis and structure-activity relationship (SAR) of dipyridodiazepinone analogs; in the meantime, the mechanism of action is also presented. It will pave the way for the design and development of novel dipyridodiazepinone analogs as NNRTIs in AIDS chemotherapy in the future.

Immortalization of pig fibroblast cells by transposon-mediated ectopic expression of porcine telomerase reverse transcriptase.

PubMed

He, Shan; Li, Yangyang; Chen, Yang; Zhu, Yue; Zhang, Xinyu; Xia, Xiaoli; Sun, Huaichang

2016-08-01

Pigs are the most economically important livestock, but pig cell lines useful for physiological studies and/or vaccine development are limited. Although several pig cell lines have been generated by oncogene transformation or human telomerase reverse transcriptase (TERT) immortalization, these cell lines contain viral sequences and/or antibiotic resistance genes. In this study, we established a new method for generating pig cell lines using the Sleeping Beauty (SB) transposon-mediated ectopic expression of porcine telomerase reverse transcriptase (pTERT). The performance of the new method was confirmed by generating a pig fibroblast cell (PFC) line. After transfection of primary PFCs with the SB transposon system, one cell clone containing the pTERT expression cassette was selected by dilution cloning and passed for different generations. After passage for more than 40 generations, the cell line retained stable expression of ectopic pTERT and continuous growth potential. Further characterization showed that the cell line kept the fibroblast morphology, growth curve, population doubling time, cloning efficiency, marker gene expression pattern, cell cycle distribution and anchorage-dependent growth property of the primary cells. These data suggest that the new method established is useful for generating pig cell lines without viral sequence and antibiotic resistant gene.

Mitochondrial telomerase reverse transcriptase binds to and protects mitochondrial DNA and function from damage.

PubMed

Haendeler, Judith; Dröse, Stefan; Büchner, Nicole; Jakob, Sascha; Altschmied, Joachim; Goy, Christine; Spyridopoulos, Ioakim; Zeiher, Andreas M; Brandt, Ulrich; Dimmeler, Stefanie

2009-06-01

The enzyme telomerase and its catalytic subunit the telomerase reverse transcriptase (TERT) are important for maintenance of telomere length in the nucleus. Recent studies provided evidence for a mitochondrial localization of TERT. Therefore, we investigated the exact localization of TERT within the mitochondria and its function. Here, we demonstrate that TERT is localized in the matrix of the mitochondria. TERT binds to mitochondrial DNA at the coding regions for ND1 and ND2. Binding of TERT to mitochondrial DNA protects against ethidium bromide-induced damage. TERT increases overall respiratory chain activity, which is most pronounced at complex I and dependent on the reverse transcriptase activity of the enzyme. Moreover, mitochondrial reactive oxygen species are increased after genetic ablation of TERT by shRNA. Mitochondrially targeted TERT and not wild-type TERT revealed the most prominent protective effect on H(2)O(2)-induced apoptosis. Lung fibroblasts from 6-month-old TERT(-/-) mice (F2 generation) showed increased sensitivity toward UVB radiation and heart mitochondria exhibited significantly reduced respiratory chain activity already under basal conditions, demonstrating the protective function of TERT in vivo. Mitochondrial TERT exerts a novel protective function by binding to mitochondrial DNA, increasing respiratory chain activity and protecting against oxidative stress-induced damage.

Occurrence of transmitted HIV-1 drug resistance among Drug-naïve pregnant women in selected HIV-care centres in Ghana.

PubMed

Martin-Odoom, Alexander; Adiku, Theophilus; Delgado, Elena; Lartey, Margaret; Ampofo, William K

2017-03-01

Access to antiretroviral therapy in Ghana has been scaled up across the country over the last decade. This study sought to determine the occurrence of transmitted HIV-1 drug resistance in pregnant HIV-1 positive women yet to initiate antiretroviral therapy at selected HIV Care Centres in Ghana. Plasma specimens from twenty-six (26) HIV seropositive pregnant women who were less than 28weeks pregnant with their first pregnancy and ART naïve were collected from selected HIV care centres in three (3) regions in Ghana. Genotypic testing was done for the reverse transcriptase gene and the sequences generated were analyzed for HIV-1 drug resistance mutations using the Stanford University HIV Drug Resistance Database. Resistance mutations associated with the reverse transcriptase gene were detected in 4 (15.4%) of the participants. At least one major drug resistance mutation in the reverse transcriptase gene was found in 3 (11.5%) of the women. The detection of transmitted HIV-1 drug resistance in this drug-naïve group in two regional HIV care sites is an indication of the need for renewed action in monitoring the emergence of transmitted HIV-1 drug resistance in Ghana. None declared.

Base Preferences in Non-Templated Nucleotide Incorporation by MMLV-Derived Reverse Transcriptases

PubMed Central

Zajac, Pawel; Islam, Saiful; Hochgerner, Hannah; Lönnerberg, Peter; Linnarsson, Sten

2013-01-01

Reverse transcriptases derived from Moloney Murine Leukemia Virus (MMLV) have an intrinsic terminal transferase activity, which causes the addition of a few non-templated nucleotides at the 3´ end of cDNA, with a preference for cytosine. This mechanism can be exploited to make the reverse transcriptase switch template from the RNA molecule to a secondary oligonucleotide during first-strand cDNA synthesis, and thereby to introduce arbitrary barcode or adaptor sequences in the cDNA. Because the mechanism is relatively efficient and occurs in a single reaction, it has recently found use in several protocols for single-cell RNA sequencing. However, the base preference of the terminal transferase activity is not known in detail, which may lead to inefficiencies in template switching when starting from tiny amounts of mRNA. Here, we used fully degenerate oligos to determine the exact base preference at the template switching site up to a distance of ten nucleotides. We found a strong preference for guanosine at the first non-templated nucleotide, with a greatly reduced bias at progressively more distant positions. Based on this result, and a number of careful optimizations, we report conditions for efficient template switching for cDNA amplification from single cells. PMID:24392002

High-throughput sequencing of human plasma RNA by using thermostable group II intron reverse transcriptases

PubMed Central

Qin, Yidan; Yao, Jun; Wu, Douglas C.; Nottingham, Ryan M.; Mohr, Sabine; Hunicke-Smith, Scott; Lambowitz, Alan M.

2016-01-01

Next-generation RNA-sequencing (RNA-seq) has revolutionized transcriptome profiling, gene expression analysis, and RNA-based diagnostics. Here, we developed a new RNA-seq method that exploits thermostable group II intron reverse transcriptases (TGIRTs) and used it to profile human plasma RNAs. TGIRTs have higher thermostability, processivity, and fidelity than conventional reverse transcriptases, plus a novel template-switching activity that can efficiently attach RNA-seq adapters to target RNA sequences without RNA ligation. The new TGIRT-seq method enabled construction of RNA-seq libraries from <1 ng of plasma RNA in <5 h. TGIRT-seq of RNA in 1-mL plasma samples from a healthy individual revealed RNA fragments mapping to a diverse population of protein-coding gene and long ncRNAs, which are enriched in intron and antisense sequences, as well as nearly all known classes of small ncRNAs, some of which have never before been seen in plasma. Surprisingly, many of the small ncRNA species were present as full-length transcripts, suggesting that they are protected from plasma RNases in ribonucleoprotein (RNP) complexes and/or exosomes. This TGIRT-seq method is readily adaptable for profiling of whole-cell, exosomal, and miRNAs, and for related procedures, such as HITS-CLIP and ribosome profiling. PMID:26554030

[The use of complex interval models for predicting activity of non-nucleoside reverse transcriptase activity].

PubMed

Burliaeva, E V; Tarkhov, A E; Burliaev, V V; Iurkevich, A M; Shvets, V I

2002-01-01

Searching of new anti-HIV agents is still crucial now. In general, researches are looking for inhibitors of certain HIV's vital enzymes, especially for reverse transcriptase (RT) inhibitors. Modern generation of anti-HIV agents represents non-nucleoside reverse transcriptase inhibitors (NNRTIs). They are much less toxic than nucleoside analogues and more chemically stable, thus being slower metabolized and emitted from the human body. Thus, search of new NNRTIs is actual today. Synthesis and study of new anti-HIV drugs is very expensive. So employment of the activity prediction techniques for such a search is very beneficial. This technique allows predicting the activities for newly proposed structures. It is based on the property model built by investigation of a series of known compounds with measured activity. This paper presents an approach of activity prediction based on "structure-activity" models designed to form a hypothesis about probably activity interval estimate. This hypothesis formed is based on structure descriptor domains, calculated for all energetically allowed conformers for each compound in the studied sef. Tetrahydroimidazobenzodiazipenone (TIBO) derivatives and phenylethyltiazolyltiourea (PETT) derivatives illustrated the predictive power of this method. The results are consistent with experimental data and allow to predict inhibitory activity of compounds, which were not included into the training set.

Bufadienolides from parotoid gland secretions of Cuban toad Peltophryne fustiger (Bufonidae): Inhibition of human kidney Na(+)/K(+)-ATPase activity.

PubMed

Perera Córdova, Wilmer H; Leitão, Suzana Guimarães; Cunha-Filho, Geraldino; Bosch, Roberto Alonso; Alonso, Isel Pascual; Pereda-Miranda, Rogelio; Gervou, Rodrigo; Touza, Natália Araújo; Quintas, Luis Eduardo M; Noël, François

2016-02-01

Parotoid gland secretions of toad species are a vast reservoir of bioactive molecules with a wide range of biological properties. Herein, for the first time, it is described the isolation by preparative reversed-phase HPLC and the structure elucidation by NMR spectroscopy and/or mass spectrometry of nine major bufadienolides from parotoid gland secretions of the Cuban endemic toad Peltophryne fustiger: ψ-bufarenogin, gamabufotalin, bufarenogin, arenobufagin, 3-(N-suberoylargininyl) marinobufagin, bufotalinin, telocinobufagin, marinobufagin and bufalin. In addition, the secretion was analyzed by UPLC-MS/MS which also allowed the identification of azelayl arginine. The effect of arenobufagin, bufalin and ψ-bufarenogin on Na(+)/K(+)-ATPase activity in a human kidney preparation was evaluated. These bufadienolides fully inhibited the Na(+)/K(+)-ATPase in a concentration-dependent manner, although arenobufagin (IC50 = 28.3 nM) and bufalin (IC50 = 28.7 nM) were 100 times more potent than ψ-bufarenogin (IC50 = 3020 nM). These results provided evidence about the importance of the hydroxylation at position C-14 in the bufadienolide skeleton for the inhibitory activity on the Na(+)/K(+)-ATPase. Published by Elsevier Ltd.

A search for antiplasmodial metabolites among fungal endophytes of terrestrial and marine plants of southern India.

PubMed

Kaushik, Naveen Kumar; Murali, Thokur Sreepathy; Sahal, Dinkar; Suryanarayanan, T S

2014-10-01

Eighty four different fungal endophytes isolated from sea grasses (5), marine algae (36) and leaves or barks of forest trees (43) were grown in vitro and the secondary metabolites secreted by them were harvested by immobilizing them on XAD beads. These metabolites were eluted with methanol and screened using SYBR Green I assay for their antiplasmodial activity against blood stage Plasmodium falciparum in human red blood cell culture. Our results revealed that fungal endophytes belonging to diverse genera elaborate antiplasmodial metabolites. A Fusarium sp. (580, IC50: 1.94 μg ml(-1)) endophytic in a marine alga and a Nigrospora sp. (151, IC50: 2.88 μg ml(-1)) endophytic in a tree species were subjected to antiplasmodial activity-guided reversed phase high performance liquid chromatography separation. Purification led to potentiation as reflected in IC50 values of 0.12 μg ml(-1) and 0.15 μg ml(-1) for two of the fractions obtained from 580. Our study adds further credence to the notion that fungal endophytes are a potential storehouse for a variety of novel secondary metabolites vested with different bioactivities including some that can stall the growth of the malaria parasite.

Modified concentration method for the detection of enteric viruses on fruits and vegetables by reverse transcriptase-polymerase chain reaction or cell culture.

PubMed

Dubois, Eric; Agier, Cécilia; Traoré, Ousmane; Hennechart, Catherine; Merle, Ghislaine; Crucière, Catherine; Laveran, Henri

2002-12-01

Fruits and vegetables may act as a vehicle of human enteric virus if they are irrigated with sewage-contaminated water or prepared by infected food handlers. An elution-concentration method was modified to efficiently detect, by reverse transcriptase-polymerase chain reaction (RT-PCR) or by cell culture, contamination by poliovirus, hepatitis A virus (HAV), and Norwalk-like virus (NLV) of various fresh and frozen berries and fresh vegetables. The protocol included washing the fruit or vegetable surface with 100 mM Tris-HCl, 50 mM glycine, and 3% beef extract, pH 9.5 buffer, which favors viral elution from acid-releasing berries, supplemented with 50 mM MgCl2 to reduce the decrease in viral infectivity during the process. The viral concentration method was based on polyethylene glycol precipitation. Copurified RT-PCR inhibitors and cytotoxic compounds were removed from viral concentrates by chloroform-butanol extraction. Viruses from 100 g of vegetal products could be recovered in volumes of 3 to 5 ml. Viral RNAs were isolated by a spin column method before molecular detection or concentrates were filtered (0.22-microm porosity) and inoculated on cell culture for infectious virus detection. About 15% of infectious poliovirus and 20% of infectious HAV were recovered from frozen raspberry surfaces. The percentage of viral RNA recovery was estimated by RT-PCR to be about 13% for NLV, 17% for HAV, and 45 to 100% for poliovirus. By this method, poliovirus and HAV RNA were detected on products inoculated with a titer of about 5 x 10(1) 50% tissue culture infectious dose per 100 g. NLV RNA was detected at an initial inoculum of 1.2 x 10(3) RT-PCR amplifiable units. This method would be useful for the viral analysis of fruits or vegetables during an epidemiological investigation of foodborne diseases.

Comparison of FilmArray and Quantitative Real-Time Reverse Transcriptase PCR for Detection of Zaire Ebolavirus from Contrived and Clinical Specimens

PubMed Central

Southern, Timothy R.; Racsa, Lori D.; Albariño, César G.; Fey, Paul D.; Hinrichs, Steven H.; Murphy, Caitlin N.; Herrera, Vicki L.; Sambol, Anthony R.; Hill, Charles E.; Ryan, Emily L.; Kraft, Colleen S.; Campbell, Shelley; Sealy, Tara K.; Schuh, Amy; Ritchie, James C.; Lyon, G. Marshall; Mehta, Aneesh K.; Varkey, Jay B.; Ribner, Bruce S.; Brantly, Kent P.; Ströher, Ute; Iwen, Peter C.

2015-01-01

Rapid, reliable, and easy-to-use diagnostic assays for detection of Zaire ebolavirus (ZEBOV) are urgently needed. The goal of this study was to examine the agreement among emergency use authorization (EUA) tests for the detection of ZEBOV nucleic acids, including the BioFire FilmArray BioThreat (BT) panel, the FilmArray BT-E panel, and the NP2 and VP40 quantitative real-time reverse transcriptase (qRT) PCR assays from the Centers for Disease Control and Prevention (CDC). Specimens used in this study included whole blood spiked with inactivated ZEBOV at known titers and whole-blood, plasma, and urine clinical specimens collected from persons diagnosed with Ebola virus disease (EVD). The agreement for FilmArray and qRT-PCR results using contrived whole-blood specimens was 100% (6/6 specimens) for each ZEBOV dilution from 4 × 107 to 4 × 102 50% tissue culture infective dose (TCID50)/ml, as well as the no-virus negative-control sample. The limit of detection for FilmArray and qRT-PCR assays with inactivated ZEBOV, based on duplicate positive results, was determined to be 4 × 102 TCID50/ml. Rates of agreement between FilmArray and qRT-PCR results for clinical specimens from patients with EVD were 85% (23/27 specimens) for whole-blood specimens, 90% (18/20 specimens) for whole-blood specimens tested by FilmArray testing and matched plasma specimens tested by qRT-PCR testing, and 85% (11/13 specimens) for urine specimens. Among 60 specimens, eight discordant results were noted, with ZEBOV nucleic acids being detected only by FilmArray testing in four specimens and only by qRT-PCR testing in the remaining four specimens. These findings demonstrate that the rapid and easy-to-use FilmArray panels are effective tests for evaluating patients with EVD. PMID:26157148

Susceptibility of recombinant porcine endogenous retrovirus reverse transcriptase to nucleoside and non-nucleoside inhibitors.

PubMed

Wilhelm, M; Fishman, J A; Pontikis, R; Aubertin, A M; Wilhelm, F X

2002-12-01

Transplantation of organs, tissues or cells from pigs to humans could be a potential solution to the shortage of human organs for transplantation. Porcine endogenous retroviruses (PERVs) remain a major safety concern for porcine xenotransplantation. Thus, finding drugs that could be used as virological prophylaxis (or therapy) against PERV replication would be desirable. One of the most effective ways to block retroviral multiplication is to inhibit the enzyme reverse transcriptase (RT) which catalyzes the reverse transcription of viral RNA to proviral double-stranded DNA. We report here the cloning and expression of PERV RT and its susceptibility to several inhibitors. Our data demonstrate PERV susceptibility in vitro to the triphosphorylated nucleoside analog of zidovudine (AZT) and to ddGTP and to a lesser extent to ddTTP but almost no susceptibility to the non-nucleoside RT inhibitors tested.

Structure of a group II intron in complex with its reverse transcriptase.

PubMed

Qu, Guosheng; Kaushal, Prem Singh; Wang, Jia; Shigematsu, Hideki; Piazza, Carol Lyn; Agrawal, Rajendra Kumar; Belfort, Marlene; Wang, Hong-Wei

2016-06-01

Bacterial group II introns are large catalytic RNAs related to nuclear spliceosomal introns and eukaryotic retrotransposons. They self-splice, yielding mature RNA, and integrate into DNA as retroelements. A fully active group II intron forms a ribonucleoprotein complex comprising the intron ribozyme and an intron-encoded protein that performs multiple activities including reverse transcription, in which intron RNA is copied into the DNA target. Here we report cryo-EM structures of an endogenously spliced Lactococcus lactis group IIA intron in its ribonucleoprotein complex form at 3.8-Å resolution and in its protein-depleted form at 4.5-Å resolution, revealing functional coordination of the intron RNA with the protein. Remarkably, the protein structure reveals a close relationship between the reverse transcriptase catalytic domain and telomerase, whereas the active splicing center resembles the spliceosomal Prp8 protein. These extraordinary similarities hint at intricate ancestral relationships and provide new insights into splicing and retromobility.

Multiple nucleotide preferences determine cleavage-site recognition by the HIV-1 and M-MuLV RNases H.

PubMed

Schultz, Sharon J; Zhang, Miaohua; Champoux, James J

2010-03-19

The RNase H activity of reverse transcriptase is required during retroviral replication and represents a potential target in antiviral drug therapies. Sequence features flanking a cleavage site influence the three types of retroviral RNase H activity: internal, DNA 3'-end-directed, and RNA 5'-end-directed. Using the reverse transcriptases of HIV-1 (human immunodeficiency virus type 1) and Moloney murine leukemia virus (M-MuLV), we evaluated how individual base preferences at a cleavage site direct retroviral RNase H specificity. Strong test cleavage sites (designated as between nucleotide positions -1 and +1) for the HIV-1 and M-MuLV enzymes were introduced into model hybrid substrates designed to assay internal or DNA 3'-end-directed cleavage, and base substitutions were tested at specific nucleotide positions. For internal cleavage, positions +1, -2, -4, -5, -10, and -14 for HIV-1 and positions +1, -2, -6, and -7 for M-MuLV significantly affected RNase H cleavage efficiency, while positions -7 and -12 for HIV-1 and positions -4, -9, and -11 for M-MuLV had more modest effects. DNA 3'-end-directed cleavage was influenced substantially by positions +1, -2, -4, and -5 for HIV-1 and positions +1, -2, -6, and -7 for M-MuLV. Cleavage-site distance from the recessed end did not affect sequence preferences for M-MuLV reverse transcriptase. Based on the identified sequence preferences, a cleavage site recognized by both HIV-1 and M-MuLV enzymes was introduced into a sequence that was otherwise resistant to RNase H. The isolated RNase H domain of M-MuLV reverse transcriptase retained sequence preferences at positions +1 and -2 despite prolific cleavage in the absence of the polymerase domain. The sequence preferences of retroviral RNase H likely reflect structural features in the substrate that favor cleavage and represent a novel specificity determinant to consider in drug design. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Structure of the HIV-1 reverse transcriptase Q151M mutant: insights into the inhibitor resistance of HIV-1 reverse transcriptase and the structure of the nucleotide-binding pocket of Hepatitis B virus polymerase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakamura, Akiyoshi; Tamura, Noriko; Yasutake, Yoshiaki, E-mail: y-yasutake@aist.go.jp

The structure of the HIV-1 reverse transcriptase Q151M mutant was determined at a resolution of 2.6 Å in space group P321. Hepatitis B virus polymerase (HBV Pol) is an important target for anti-HBV drug development; however, its low solubility and stability in vitro has hindered detailed structural studies. Certain nucleotide reverse transcriptase (RT) inhibitors (NRTIs) such as tenofovir and lamivudine can inhibit both HBV Pol and Human immunodeficiency virus 1 (HIV-1) RT, leading to speculation on structural and mechanistic analogies between the deoxynucleotide triphosphate (dNTP)-binding sites of these enzymes. The Q151M mutation in HIV-1 RT, located at the dNTP-binding site,more » confers resistance to various NRTIs, while maintaining sensitivity to tenofovir and lamivudine. The residue corresponding to Gln151 is strictly conserved as a methionine in HBV Pol. Therefore, the structure of the dNTP-binding pocket of the HIV-1 RT Q151M mutant may reflect that of HBV Pol. Here, the crystal structure of HIV-1 RT Q151M, determined at 2.6 Å resolution, in a new crystal form with space group P321 is presented. Although the structure of HIV-1 RT Q151M superimposes well onto that of HIV-1 RT in a closed conformation, a slight movement of the β-strands (β2–β3) that partially create the dNTP-binding pocket was observed. This movement might be caused by the introduction of the bulky thioether group of Met151. The structure also highlighted the possibility that the hydrogen-bonding network among amino acids and NRTIs is rearranged by the Q151M mutation, leading to a difference in the affinity of NRTIs for HIV-1 RT and HBV Pol.« less

Role of the K101E Substitution in HIV-1 Reverse Transcriptase in Resistance to Rilpivirine and Other Nonnucleoside Reverse Transcriptase Inhibitors

PubMed Central

Xu, Hong-Tao; Colby-Germinario, Susan P.; Huang, Wei; Oliveira, Maureen; Han, Yingshan; Quan, Yudong; Petropoulos, Christos J.

2013-01-01

Resistance to the recently approved nonnucleoside reverse transcriptase inhibitor (NNRTI) rilpivirine (RPV) commonly involves substitutions at positions E138K and K101E in HIV-1 reverse transcriptase (RT), together with an M184I substitution that is associated with resistance to coutilized emtricitabine (FTC). Previous biochemical and virological studies have shown that compensatory interactions between substitutions E138K and M184I can restore enzyme processivity and the viral replication capacity. Structural modeling studies have also shown that disruption of the salt bridge between K101 and E138 can affect RPV binding. The current study was designed to investigate the impact of K101E, alone or in combination with E138K and/or M184I, on drug susceptibility, viral replication capacity, and enzyme function. We show here that K101E can be selected in cell culture by the NNRTIs etravirine (ETR), efavirenz (EFV), and dapivirine (DPV) as well as by RPV. Recombinant RT enzymes and viruses containing K101E, but not E138K, were highly resistant to nevirapine (NVP) and delavirdine (DLV) as well as ETR and RPV, but not EFV. The addition of K101E to E138K slightly enhanced ETR and RPV resistance compared to that obtained with E138K alone but restored susceptibility to NVP and DLV. The K101E substitution can compensate for deficits in viral replication capacity and enzyme processivity associated with M184I, while M184I can compensate for the diminished efficiency of DNA polymerization associated with K101E. The coexistence of K101E and E138K does not impair either viral replication or enzyme fitness. We conclude that K101E can play a significant role in resistance to RPV. PMID:24002090

Role of the K101E substitution in HIV-1 reverse transcriptase in resistance to rilpivirine and other nonnucleoside reverse transcriptase inhibitors.

PubMed

Xu, Hong-Tao; Colby-Germinario, Susan P; Huang, Wei; Oliveira, Maureen; Han, Yingshan; Quan, Yudong; Petropoulos, Christos J; Wainberg, Mark A

2013-11-01

Resistance to the recently approved nonnucleoside reverse transcriptase inhibitor (NNRTI) rilpivirine (RPV) commonly involves substitutions at positions E138K and K101E in HIV-1 reverse transcriptase (RT), together with an M184I substitution that is associated with resistance to coutilized emtricitabine (FTC). Previous biochemical and virological studies have shown that compensatory interactions between substitutions E138K and M184I can restore enzyme processivity and the viral replication capacity. Structural modeling studies have also shown that disruption of the salt bridge between K101 and E138 can affect RPV binding. The current study was designed to investigate the impact of K101E, alone or in combination with E138K and/or M184I, on drug susceptibility, viral replication capacity, and enzyme function. We show here that K101E can be selected in cell culture by the NNRTIs etravirine (ETR), efavirenz (EFV), and dapivirine (DPV) as well as by RPV. Recombinant RT enzymes and viruses containing K101E, but not E138K, were highly resistant to nevirapine (NVP) and delavirdine (DLV) as well as ETR and RPV, but not EFV. The addition of K101E to E138K slightly enhanced ETR and RPV resistance compared to that obtained with E138K alone but restored susceptibility to NVP and DLV. The K101E substitution can compensate for deficits in viral replication capacity and enzyme processivity associated with M184I, while M184I can compensate for the diminished efficiency of DNA polymerization associated with K101E. The coexistence of K101E and E138K does not impair either viral replication or enzyme fitness. We conclude that K101E can play a significant role in resistance to RPV.

Hybrid chemistry. Part 4: Discovery of etravirine-VRX-480773 hybrids as potent HIV-1 non-nucleoside reverse transcriptase inhibitors.

PubMed

Wan, Zheng-Yong; Tao, Yuan; Wang, Ya-Feng; Mao, Tian-Qi; Yin, Hong; Chen, Fen-Er; Piao, Hu-Ri; De Clercq, Erik; Daelemans, Dirk; Pannecouque, Christophe

2015-08-01

A novel series of etravirine-VRX-480773 hybrids were designed using structure-guided molecular hybridization strategy and fusing the pharmacophore templates of etravirine and VRX-480773. The anti-HIV-1 activity and cytotoxicity was evaluated in MT-4 cell cultures. The most active hybrid compound in this series, N-(2-chlorophenyl)-2-((4-(4-cyano-2,6-dimethylphenoxy)pyrimidin-2-yl)thio)acetamide 3d (EC50=0.24 , SI>1225), was more potent than delavirdine (EC50=0.66 μM, SI>67) in the anti-HIV-1 in vitro cellular assay. Studies of structure-activity relationships established a correlation between anti-HIV activity and the substitution pattern of the acetanilide group. Copyright © 2015 Elsevier Ltd. All rights reserved.

The muscarinic antagonists scopolamine and atropine are competitive antagonists at 5-HT3 receptors.

PubMed

Lochner, Martin; Thompson, Andrew J

2016-09-01

Scopolamine is a high affinity muscarinic antagonist that is used for the prevention of post-operative nausea and vomiting. 5-HT3 receptor antagonists are used for the same purpose and are structurally related to scopolamine. To examine whether 5-HT3 receptors are affected by scopolamine we examined the effects of this drug on the electrophysiological and ligand binding properties of 5-HT3A receptors expressed in Xenopus oocytes and HEK293 cells, respectively. 5-HT3 receptor-responses were reversibly inhibited by scopolamine with an IC50 of 2.09 μM. Competitive antagonism was shown by Schild plot (pA2 = 5.02) and by competition with the 5-HT3 receptor antagonists [(3)H]granisetron (Ki = 6.76 μM) and G-FL (Ki = 4.90 μM). The related molecule, atropine, similarly inhibited 5-HT evoked responses in oocytes with an IC50 of 1.74 μM, and competed with G-FL with a Ki of 7.94 μM. The reverse experiment revealed that granisetron also competitively bound to muscarinic receptors (Ki = 6.5 μM). In behavioural studies scopolamine is used to block muscarinic receptors and induce a cognitive deficit, and centrally administered concentrations can exceed the IC50 values found here. It is therefore possible that 5-HT3 receptors are also inhibited. Studies that utilise higher concentrations of scopolamine should be mindful of these potential off-target effects. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Arylazolyl(azinyl)thioacetanilides. Part 16: Structure-based bioisosterism design, synthesis and biological evaluation of novel pyrimidinylthioacetanilides as potent HIV-1 inhibitors.

PubMed

Li, Xiao; Lu, Xueyi; Chen, Wenmin; Liu, Huiqing; Zhan, Peng; Pannecouque, Christophe; Balzarini, Jan; De Clercq, Erik; Liu, Xinyong

2014-10-01

A series of novel pyrimidinylthioacetanilides were designed, synthesized, and evaluated for their biological activity as potent HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs). Most of the tested compounds were proved to be effective in inhibiting HIV-1 (IIIB) replication with EC50 ranging from 0.15 μM to 24.2 μM, thereinto compound 15 was the most active lead with favorable inhibitory activity against HIV-1 (IIIB) (EC50=0.15 μM, SI=684). Besides, compound 6 displayed moderate inhibition against the double-mutated HIV-1 strain (K103N/Y181C) (EC50=3.9 μM). Preliminary structure-activity relationships (SARs), structure-cytotoxicity relationships (SCRs) data, and molecular modeling studies were discussed as well, which may provide valuable insights for further optimizations. Copyright © 2014 Elsevier Ltd. All rights reserved.

Novel angiotensin I-converting enzyme inhibitory peptides isolated from Alcalase hydrolysate of mung bean protein.

PubMed

Li, Guan-Hong; Wan, Ju-Zhen; Le, Guo-Wei; Shi, Yong-Hui

2006-08-01

Mung bean protein isolates were hydrolyzed for 2 h by Alcalase. The generated hydrolysate showed angiotensin I-converting enzyme (ACE) inhibitory activity with the IC(50) value of 0.64 mg protein/ml. Three kinds of novel ACE inhibitory peptides were isolated from the hydrolysate by Sephadex G-15 and reverse-phase high performance liquid chromatography (RP-HPLC). These peptides were identified by amino acid composition analysis and matrix assisted-laser desorption/ionization time-of-flight tandem mass spectrometry (MALDI-TOF MS/MS), as Lys-Asp-Tyr-Arg-Leu, Val-Thr-Pro-Ala-Leu-Arg and Lys-Leu-Pro-Ala-Gly-Thr-Leu-Phe with the IC(50) values of 26.5 microM, 82.4 microM and 13.4 microM, respectively. Copyright (c) 2006 European Peptide Society and John Wiley & Sons, Ltd.

Indanones as high-potency reversible inhibitors of monoamine oxidase.

PubMed

Mostert, Samantha; Petzer, Anél; Petzer, Jacobus P

2015-05-01

Recent reports document that α-tetralone (3,4-dihydro-2H-naphthalen-1-one) is an appropriate scaffold for the design of high-potency monoamine oxidase (MAO) inhibitors. Based on the structural similarity between α-tetralone and 1-indanone, the present study involved synthesis of 34 1-indanone and related indane derivatives as potential inhibitors of recombinant human MAO-A and MAO-B. The results show that C6-substituted indanones are particularly potent and selective MAO-B inhibitors, with IC50 values ranging from 0.001 to 0.030 μM. C5-Substituted indanone and indane derivatives are comparatively weaker MAO-B inhibitors. Although the 1-indanone and indane derivatives are selective inhibitors of the MAO-B isoform, a number of homologues are also potent MAO-A inhibitors, with three homologues possessing IC50 values <0.1 μM. Dialysis of enzyme-inhibitor mixtures further established a selected 1-indanone as a reversible MAO inhibitor with a competitive mode of inhibition. It may be concluded that 1-indanones are promising leads for the design of therapies for neurodegenerative and neuropsychiatric disorders such as Parkinson's disease and depression. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Probing the molecular mechanism of action of the HIV-1 reverse transcriptase inhibitor 4'-ethynyl-2-fluoro-2'-deoxyadenosine (EFdA) using pre-steady-state kinetics.

PubMed

Muftuoglu, Yagmur; Sohl, Christal D; Mislak, Andrea C; Mitsuya, Hiroaki; Sarafianos, Stefan G; Anderson, Karen S

2014-06-01

The novel antiretroviral 4'-ethynyl-2-fluoro-2'-deoxyadenosine (EFdA) is a potent nucleoside HIV-1 reverse transcriptase (RT) inhibitor (NRTI). Unlike other FDA-approved NRTIs, EFdA contains a 3'-hydroxyl. Pre-steady-state kinetics showed RT preferred incorporating EFdA-TP over native dATP. Moreover, RT slowly inserted nucleotides past an EFdA-terminated primer, resulting in delayed chain termination with unaffected fidelity. This is distinct from KP1212, another 3'-hydroxyl-containing RT inhibitor considered to promote viral lethal mutagenesis. New mechanistic features of RT inhibition by EFdA are revealed. Copyright © 2014 Elsevier B.V. All rights reserved.

Probing the molecular mechanism of action of the HIV-1 reverse transcriptase inhibitor 4′-ethynyl-2-fluoro-2′-deoxyadenosine (EFdA) using pre-steady-state kinetics

PubMed Central

Muftuoglu, Yagmur; Sohl, Christal D.; Mislak, Andrea C.; Mitsuya, Hiroaki; Sarafianos, Stefan G.; Anderson, Karen S.

2014-01-01

The novel antiretroviral 4′-ethynyl-2-fluoro-2′-deoxyadenosine (EFdA) is a potent nucleoside HIV-1 reverse transcriptase (RT) inhibitor (NRTI). Unlike other FDA-approved NRTIs, EFdA contains a 3′-hydroxyl. Pre-steady-state kinetics showed RT preferred incorporating EFdA-TP over native dATP. Moreover, RT slowly inserted nucleotides past an EFdA-terminated primer, resulting in delayed chain termination with unaffected fidelity. This is distinct from KP1212, another 3′-hydroxyl-containing RT inhibitor considered to promote viral lethal mutagenesis. New mechanistic features of RT inhibition by EFdA are revealed. PMID:24632447

Leptin upregulates telomerase activity and transcription of human telomerase reverse transcriptase in MCF-7 breast cancer cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, He, E-mail: herenrh@yahoo.com.cn; Zhao, Tiansuo; Wang, Xiuchao

2010-03-26

The aim was to analyze the mechanism of leptin-induced activity of telomerase in MCF-7 breast cancer cells. We found that leptin activated telomerase in a dose-dependent manner; leptin upregulated the expression of Human Telomerase Reverse Transcriptase (hTERT) at mRNA and protein levels; blockade of signal transducer and activator of transcription 3 (STAT3) phosphorylation significantly counteracted leptin-induced hTERT transcription and protein expression; chromatin immunoprecipitation analysis showed that leptin enhanced the binding of STAT3 to the hTERT promoter. This study uncovers a new mechanism of the proliferative effect of leptin on breast cancer cells and provides a new explanation of obesity-related breastmore » cancer.« less

Oligonucleotide microarray analysis of gene expression profiles followed by real-time reverse-transcriptase polymerase chain reaction assay in chronic active Epstein-Barr virus infection.

PubMed

Ito, Yoshinori; Shibata-Watanabe, Yukiko; Ushijima, Yoko; Kawada, Jun-Ichi; Nishiyama, Yukihiro; Kojima, Seiji; Kimura, Hiroshi

2008-03-01

Chronic active Epstein-Barr virus infection (CAEBV) is characterized by recurrent infectious mononucleosis-like symptoms and has high mortality and morbidity. To clarify the mechanisms of CAEBV, the gene-expression profiles of peripheral blood obtained from patients with CAEBV were investigated. Twenty genes were differentially expressed in 4 patients with CAEBV. This microarray result was verified using a real-time reverse-transcriptase polymerase chain reaction assay in a larger group of patients with CAEBV. Eventually, 3 genes were found to be significantly upregulated: guanylate binding protein 1, tumor necrosis factor-induced protein 6, and guanylate binding protein 5. These genes may be associated with the inflammatory reaction or with cell proliferation.

The origin and early evolution of nucleic acid polymerases

NASA Technical Reports Server (NTRS)

Lazcano, A.; Cappello, R.; Valverde, V.; Llaca, V.; Oro, J.

1992-01-01

The hypothesis that vestiges of the ancestral RNA-dependent RNA polymerase involved in the replication of RNA genomes of Archean cells are present in the eubacterial RNA-polymerase beta-prime subunit and its homologues is discussed. It is shown that, in the DNA-dependent RNA polymerases from three cellular lineages, a very conserved sequence of eight amino acids, also found in a small RNA-binding site previously described for the E. coli polynucleotide phosphorylase and the S1 ribosomal protein, is present. The optimal conditions for the replicase activity of the avian-myeloblastosis-virus reverse transcriptase are presented. The evolutionary significance of the in vitro modifications of substrate and template specificities of RNA polymerases and reverse transcriptases is discussed.

In Vitro Cross-Resistance Profiles of Rilpivirine, Dapivirine, and MIV-150, Nonnucleoside Reverse Transcriptase Inhibitor Microbicides in Clinical Development for the Prevention of HIV-1 Infection.

PubMed

Giacobbi, Nicholas S; Sluis-Cremer, Nicolas

2017-07-01

Rilpivirine (RPV), dapivirine (DPV), and MIV-150 are in development as microbicides. It is not known whether they will block infection of circulating nonnucleoside reverse transcriptase inhibitor (NNRTI)-resistant human immunodeficiency virus type 1 (HIV-1) variants. Here, we demonstrate that the activity of DPV and MIV-150 is compromised by many resistant viruses containing single or double substitutions. High DPV genital tract concentrations from DPV ring use may block replication of resistant viruses. However, MIV-150 genital tract concentrations may be insufficient to inhibit many resistant viruses, including those harboring K103N or Y181C. Copyright © 2017 American Society for Microbiology.

Elucidation of the TMab-6 Monoclonal Antibody Epitope Against Telomerase Reverse Transcriptase.

PubMed

Kaneko, Mika K; Yamada, Shinji; Itai, Shunsuke; Chang, Yao-Wen; Nakamura, Takuro; Yanaka, Miyuki; Harada, Hiroyuki; Suzuki, Hiroyoshi; Kato, Yukinari

2018-05-03

Telomerase reverse transcriptase (TERT) and mutations of the TERT promoter are significant in the pathogenesis of 1p/19q-codeleted oligodendrogliomas and isocitrate dehydrogenase gene wild-type glioblastomas, as well as melanomas and squamous cell carcinomas. We previously developed an antihuman TERT monoclonal antibody (mAb), TMab-6, which is applicable in immunohistochemistry for human tissues. However, the binding epitope of TMab-6 against TERT is yet to be elucidated. In this study, enzyme-linked immunosorbent assay and immunohistochemistry were utilized for investigating the epitope of TMab-6. The findings revealed that the critical epitope of TMab-6 is the TERT sequence PSTSRPPRPWD; Thr310 and Ser311 of TERT are especially significant amino acids for TMab-6 recognition.

Comparative evaluation of PLGA nanoparticle delivery system for 5-fluorouracil and curcumin on squamous cell carcinoma.

PubMed

Masloub, Shaimaa M; Elmalahy, Mohamed H; Sabry, Dina; Mohamed, Wael S; Ahmed, Sahar H

2016-04-01

The purpose of this study is to assess the effect of 5-fluorouracil nanoparticles and curcumin naoparticles on cell proliferation and the expression of the apoptotic marker (caspase 3) in squamous cell carcinoma cell line. PLGA 5-fluorouracil nanopartciles and PLGA curcumin nanoparticles were prepared and applied for 24 and 48h on human laryngeal squamous carcinoma cell line (Hep-2) as regard IC 50 concentration. MTT assay was used for evaluation of cytotoxicity of prepared nanoparticles. Quantitaive reverse transcriptase polymerase chain reaction (QRT-PCR) was used for the assessment of caspase-3 expression in the treated cell line. The drug release rate profiles was dependent upon polymer to drug ratio, noting that the higher PLGA polymer ratio to 5-fluprouracil or curcumin drug showed faster release rates. On the other hand, the least PLGA polymer ratio to 5-fluprouracil or curcumin drug showed the slowest release rates. MTT assay revelaed that 5-fluorouracil nanoparticels or curcumin nanoparticels showed a clear cytotoxic effect on Hep-2 cell line compared to non treated cancer cells. The RT-PCR assessment of caspase-3 expression revealed that there was a significant increase in caspase-3 expression in Hep-2 cell line treated with 5-fluorouracil nanoparticles or curcumin compared to non treated cancer cells. Curcumin nanoparticles could be more active in inducing apoptosis in short term assays (24h) than long term assays (48h) due to differential cellular uptake. While 5-fluorouracil nanoparticles induced higher significant apoptosis in long term (48h) compared to curcumin group. Copyright © 2015 Elsevier Ltd. All rights reserved.

Antagonistic activity of Ocimum sanctum L. essential oil on growth and zearalenone production by Fusarium graminearum in maize grains.

PubMed

Kalagatur, Naveen K; Mudili, Venkataramana; Siddaiah, Chandranayaka; Gupta, Vijai K; Natarajan, Gopalan; Sreepathi, Murali H; Vardhan, Batra H; Putcha, Venkata L R

2015-01-01

The present study was aimed to establish the antagonistic effects of Ocimum sanctum L. essential oil (OSEO) on growth and zearalenone (ZEA) production of Fusarium graminearum. GC-MS chemical profiling of OSEO revealed the existence of 43 compounds and the major compound was found to be eugenol (34.7%). DPPH free radical scavenging activity (IC50) of OSEO was determined to be 8.5 μg/mL. Minimum inhibitory concentration and minimum fungicidal concentration of OSEO on F. graminearum were recorded as 1250 and 1800 μg/mL, respectively. Scanning electron microscope observations showed significant micro morphological damage in OSEO exposed mycelia and spores compared to untreated control culture. Quantitative UHPLC studies revealed that OSEO negatively effected the production of ZEA; the concentration of toxin production was observed to be insignificant at 1500 μg/mL concentration of OSEO. On other hand ZEA concentration was quantified as 3.23 μg/mL in OSEO untreated control culture. Reverse transcriptase qPCR analysis of ZEA metabolic pathway genes (PKS4 and PKS13) revealed that increase in OSEO concentration (250-1500 μg/mL) significantly downregulated the expression of PKS4 and PKS13. These results were in agreement with the artificially contaminated maize grains as well. In conlusion, the antifungal and antimycotoxic effects of OSEO on F. graminearum in the present study reiterated that, the essential oil of O. sanctum could be a promising herbal fungicide in food processing industries as well as grain storage centers.

Antagonistic activity of Ocimum sanctum L. essential oil on growth and zearalenone production by Fusarium graminearum in maize grains

PubMed Central

Kalagatur, Naveen K.; Mudili, Venkataramana; Siddaiah, Chandranayaka; Gupta, Vijai K.; Natarajan, Gopalan; Sreepathi, Murali H.; Vardhan, Batra H.; Putcha, Venkata L. R.

2015-01-01

The present study was aimed to establish the antagonistic effects of Ocimum sanctum L. essential oil (OSEO) on growth and zearalenone (ZEA) production of Fusarium graminearum. GC–MS chemical profiling of OSEO revealed the existence of 43 compounds and the major compound was found to be eugenol (34.7%). DPPH free radical scavenging activity (IC50) of OSEO was determined to be 8.5 μg/mL. Minimum inhibitory concentration and minimum fungicidal concentration of OSEO on F. graminearum were recorded as 1250 and 1800 μg/mL, respectively. Scanning electron microscope observations showed significant micro morphological damage in OSEO exposed mycelia and spores compared to untreated control culture. Quantitative UHPLC studies revealed that OSEO negatively effected the production of ZEA; the concentration of toxin production was observed to be insignificant at 1500 μg/mL concentration of OSEO. On other hand ZEA concentration was quantified as 3.23 μg/mL in OSEO untreated control culture. Reverse transcriptase qPCR analysis of ZEA metabolic pathway genes (PKS4 and PKS13) revealed that increase in OSEO concentration (250–1500 μg/mL) significantly downregulated the expression of PKS4 and PKS13. These results were in agreement with the artificially contaminated maize grains as well. In conlusion, the antifungal and antimycotoxic effects of OSEO on F. graminearum in the present study reiterated that, the essential oil of O. sanctum could be a promising herbal fungicide in food processing industries as well as grain storage centers. PMID:26388846

Atypical antipsychotic clozapine reversed deficit on prepulse inhibition of the acoustic startle reflex produced by microinjection of DOI into the inferior colliculus in rats.

PubMed

de Oliveira, Rodolpho Pereira; Nagaishi, Karen Yuriko; Barbosa Silva, Regina Cláudia

2017-05-15

Dysfunctions of the serotonergic system have been suggested to be important in the neurobiology of schizophrenia. Patients with schizophrenia exhibit deficits in an operational measure of sensorimotor gating: prepulse inhibition (PPI) of startle. PPI is the normal reduction in the startle response caused by a low intensity non-startling stimulus (prepulse) which is presented shortly before the startle stimulus (pulse). The hallucinogen 2,5-dimethoxy-4-iodoamphetamine (DOI), a 5-hydroxytryptamine(HT) 2 receptor agonist disrupted PPI in rats. The inferior colliculus (IC) is a critical nucleus of the auditory pathway mediating acoustic PPI. The activation of the IC by the acoustic prepulse reduces startle magnitude. The present study investigated the role of serotonergic transmission in the IC on the expression of acoustic PPI. For that we investigated whether 5-HT2A receptor activation or blockade would affect this response. Unilateral microinjection of DOI (10μg/0.3μl) into the IC disrupted PPI, while microinjection of the 5-HT2A receptor antagonist ritanserin (4μg/0.3μl), into this structure did not alter PPI. We also examined the ability of the atypical antipsychotic clozapine (5.0mg/kg; I.P.) to reverse the disruption of PPI produced by unilateral microinjections of DOI into the IC of rats. Pretreatment with clozapine blocked DOI-induced disruption of PPI. Altogether, these results suggest that serotonin-mediated mechanisms of the IC are involved in the expression of PPI in rodents and that this response is sensitive to atypical antipsychotic clozapine. Copyright © 2017 Elsevier B.V. All rights reserved.

Atypical antipsychotic olanzapine reversed deficit on prepulse inhibition of the acoustic startle reflex produced by microinjection of dizocilpine (MK-801) into the inferior colliculus in rats.

PubMed

Zangrando, Julia; Carvalheira, Renata; Labbate, Giovanna; Medeiros, Priscila; Longo, Beatriz Monteiro; Melo-Thomas, Liana; Silva, Regina Claudia Barbosa

2013-11-15

Patients with schizophrenia exhibit deficits in an operational measure of sensorimotor gating: prepulse inhibition (PPI) of startle. PPI is the normal reduction in the startle response caused by a low intensity non-startling stimulus (prepulse) which is presented shortly before the startle stimulus (pulse). MK-801 is an NMDA receptor-antagonist known to produce hyperactivity, deficits in prepulse inhibition and social withdrawal, behaviors which correlate well with some of the positive, cognitive and negative symptoms of schizophrenia. The inferior colliculus (IC) is a critical part of the auditory pathway mediating acoustic PPI. The activation of the IC by the acoustic prepulse reduces startle magnitude. Thus, the purpose of the present study was to elucidate the role of glutamatergic transmission in the IC on the expression of acoustic PPI. For that we investigated whether NMDA receptor stimulation or blockade would affect this response. Unilateral microinjections of NMDA (30 nmol/0.5 μL) into the IC did not alter PPI while microinjections of MK-801 (30 nmol/0.5 μL) into this structure disrupted PPI. We also examined the ability of the atypical antipsychotic olanzapine (5.0mg/kg; i.p.) to reverse the disruption of pre-pulse inhibition produced by unilateral microinjections of MK-801 into the IC of rats. Pretreatment with olanzapine blocked MK-801-induced disruption of PPI. Altogether, these results suggest that glutamate-mediated mechanisms of the IC are involved in the expression of PPI in rodents and that this response is sensitive to atypical antipsychotic olanzapine. Copyright © 2013 Elsevier B.V. All rights reserved.

Dihydropyrimidones: As novel class of β-glucuronidase inhibitors.

PubMed

Ali, Farman; Khan, Khalid Mohammed; Salar, Uzma; Iqbal, Sarosh; Taha, Muhammad; Ismail, Nor Hadiani; Perveen, Shahnaz; Wadood, Abdul; Ghufran, Mehreen; Ali, Basharat

2016-08-15

Dihydropyrimidones 1-37 were synthesized via a 'one-pot' three component reaction according to well-known Biginelli reaction by utilizing Cu(NO3)2·3H2O as catalyst, and screened for their in vitro β-glucuronidase inhibitory activity. It is worth mentioning that amongst the active molecules, compounds 8 (IC50=28.16±.056μM), 9 (IC50=18.16±0.41μM), 10 (IC50=22.14±0.43μM), 13 (IC50=34.16±0.65μM), 14 (IC50=17.60±0.35μM), 15 (IC50=15.19±0.30μM), 16 (IC50=27.16±0.48μM), 17 (IC50=48.16±1.06μM), 22 (IC50=40.16±0.85μM), 23 (IC50=44.16±0.86μM), 24 (IC50=47.16±0.92μM), 25 (IC50=18.19±0.34μM), 26 (IC50=33.14±0.68μM), 27 (IC50=44.16±0.94μM), 28 (IC50=24.16±0.50μM), 29 (IC50=34.24±0.47μM), 31 (IC50=14.11±0.21μM) and 32 (IC50=9.38±0.15μM) found to be more potent than the standard d-saccharic acid 1,4-lactone (IC50=48.4±1.25μM). Molecular docking study was conducted to establish the structure-activity relationship (SAR) which demonstrated that a number of structural features of dihydropyrimidone derivatives were involved to exhibit the inhibitory potential. All compounds were characterized by spectroscopic techniques such as (1)H, (13)C NMR, EIMS and HREI-MS. Copyright © 2016 Elsevier Ltd. All rights reserved.

Investigating the effect of emetic compounds on chemotaxis in Dictyostelium identifies a non-sentient model for bitter and hot tastant research.

PubMed

Robery, Steven; Mukanowa, Janina; Percie du Sert, Nathalie; Andrews, Paul L R; Williams, Robin S B

2011-01-01

Novel chemical entities (NCEs) may be investigated for emetic liability in a range of unpleasant experiments involving retching, vomiting or conditioned taste aversion/food avoidance in sentient animals. We have used a range of compounds with known emetic /aversive properties to examine the possibility of using the social amoeba, Dictyostelium discoideum, for research into identifying and understanding emetic liability, and hence reduce adverse animal experimentation in this area. Twenty eight emetic or taste aversive compounds were employed to investigate the acute (10 min) effect of compounds on Dictyostelium cell behaviour (shape, speed and direction of movement) in a shallow chemotaxic gradient (Dunn chamber). Compound concentrations were chosen based on those previously reported to be emetic or aversive in in vivo studies and results were recorded and quantified by automated image analysis. Dictyostelium cell motility was rapidly and strongly inhibited by four structurally distinct tastants (three bitter tasting compounds--denatonium benzoate, quinine hydrochloride, phenylthiourea, and the pungent constituent of chilli peppers--capsaicin). In addition, stomach irritants (copper chloride and copper sulphate), and a phosphodiesterase IV inhibitor also rapidly blocked movement. A concentration-dependant relationship was established for five of these compounds, showing potency of inhibition as capsaicin (IC(50) = 11.9 ± 4.0 µM) > quinine hydrochloride (IC(50) = 44.3 ± 6.8 µM) > denatonium benzoate (IC(50) = 129 ± 4 µM) > phenylthiourea (IC(50) = 366 ± 5 µM) > copper sulphate (IC(50) = 1433 ± 3 µM). In contrast, 21 compounds within the cytotoxic and receptor agonist/antagonist classes did not affect cell behaviour. Further analysis of bitter and pungent compounds showed that the effect on cell behaviour was reversible and not cytotoxic, suggesting an uncharacterised molecular mechanism of action for these compounds. These results therefore demonstrate that Dictyostelium has potential as a non-sentient model in the analysis of the molecular effects of tastants, although it has limited utility in identification of emetic agents in general.

An identified antioxidant peptide obtained from ostrich (Struthio camelus) egg white protein hydrolysate shows wound healing properties.

PubMed

Homayouni-Tabrizi, Masoud; Asoodeh, Ahmad; Abbaszadegan, Mohammad-Reza; Shahrokhabadi, Khadijeh; Nakhaie Moghaddam, Mahboobeh

2015-08-01

Ostrich (Struthio camelus) egg possesses a high amount of food proteins and thus plays an important role in nutrition. Ostrich egg white proteins were hydrolyzed with pepsin and pancreatin to examine its antioxidant properties and further characterized the most active peptide. Ostrich egg white protein hydrolysate (OEWPH) was fractionized using reversed phase high-pressure liquid chromatography (HPLC). The antioxidant activity of OEWPH and its HPLC fraction were investigated based on their scavenging capacity1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, 2,2'-azinobis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS), superoxide ([Formula: see text]), hydroxyl (OH(•-)) radicals, and Cu(+2) chelating. In a wound healing assay, paravertebral excision (1 cm diameter) was made on the skin and the percentage of wound closure was measured at defined intervals (0, 3, 7, and 14 d). A potent antioxidant peptide named DG-10 with the sequence DAESLSRLLG (MW: 1060.18 ± 0.5 Da) was identified from OEWPH. The peptide DG-10 showed DPPH (IC50 = 0.0085 mg/ml), ABTS(•+) (IC50 = 0.56 mg/ml), superoxide (IC50 = 0.36 mg/ml), and hydroxyl (IC50 = 0.4 mg/ml) radical scavenger and copper chelating activity (IC50 = 0.28 mg/ml). In vitro cultured HFLF-pI 5, the cell model, also revealed that DG-10 could protect HFLF-pI 5 cells against H2O2-treated necrosis. Ointment composed of DG-10 peptide exhibited wound-healing properties on adult rats (Wistar strain). The percentage of wound closure in peptide-treated group was 98% by day 14. Our results suggested that DG-10 is a natural agent obtained from ostrich egg possessing considerable antioxidant and wound-healing properties.

Phenoxyacetohydrazide Schiff bases: β-glucuronidase inhibitors.

PubMed

Jamil, Waqas; Perveen, Shagufta; Shah, Syed Adnan Ali; Taha, Muhammad; Ismail, Nor Hadiani; Perveen, Shahnaz; Ambreen, Nida; Khan, Khalid M; Choudhary, Muhammad I

2014-06-25

Phenoxyacetohydrazide Schiff base analogs 1-28 have been synthesized and their in vitro β-glucouoronidase inhibition potential studied. Compounds 1 (IC50=9.20±0.32 µM), 5 (IC50=9.47±0.16 µM), 7 (IC50=14.7±0.19 µM), 8 (IC50=15.4±1.56 µM), 11 (IC50=19.6±0.62 µM), 12 (IC50=30.7±1.49 µM), 15 (IC50=12.0±0.16 µM), 21 (IC50=13.7±0.40 µM) and 22 (IC50=22.0±0.14 µM) showed promising β-glucuronidase inhibition activity, better than the standard (D-saccharic acid-1,4-lactone, IC50=48.4±1.25 µM).

Synthesis of 6-chloro-2-Aryl-1H-imidazo[4,5-b]pyridine derivatives: Antidiabetic, antioxidant, β-glucuronidase inhibiton and their molecular docking studies.

PubMed

Taha, Muhammad; Ismail, Nor Hadiani; Imran, Syahrul; Rashwan, Hesham; Jamil, Waqas; Ali, Sajjad; Kashif, Syed Muhammad; Rahim, Fazal; Salar, Uzma; Khan, Khalid Mohammed

2016-04-01

6-Chloro-2-Aryl-1H-imidazo[4,5-b]pyridine derivatives 1-26 were synthesized and characterized by various spectroscopic techniques. All these derivatives were evaluated for their antiglycation, antioxidant and β-glucuronidase potential followed their docking studies. In antiglycation assay, compound 2 (IC50=240.10±2.50μM) and 4 (IC50=240.30±2.90μM) was found to be most active compound of this series, while compounds 3 (IC50=260.10±2.50μM), 6 (IC50=290.60±3.60μM), 13 (IC50=288.20±3.00μM) and 26 (IC50=292.10±3.20μM) also showed better activities than the standard rutin (IC50=294.50±1.50μM). In antioxidant assay, compound 1 (IC50=69.45±0.25μM), 2 (IC50=58.10±2.50μM), 3 (IC50=74.25±1.10μM), and 4 (IC50=72.50±3.30μM) showed good activities. In β-glucuronidase activity, compounds 3 (IC50=29.25±0.50μM), compound 1 (IC50=30.10±0.60μM) and compound 4 (IC50=46.10±1.10μM) showed a significant activity as compared to than standard D-Saccharic acid 1,4-lactonec (IC50=48.50±1.25μM) and their interaction with the enzyme was confirm by docking studies. Copyright © 2016 Elsevier Inc. All rights reserved.

Similarities between long interspersed element-1 (LINE-1) reverse transcriptase and telomerase

PubMed Central

Kopera, Huira C.; Moldovan, John B.; Morrish, Tammy A.; Moran, John V.

2011-01-01

Long interspersed element-1 (LINE-1 or L1) retrotransposons encode two proteins (ORF1p and ORF2p) that contain activities required for conventional retrotransposition by a mechanism termed target-site primed reverse transcription. Previous experiments in XRCC4 or DNA protein kinase catalytic subunit-deficient CHO cell lines, which are defective for the nonhomologous end-joining DNA repair pathway, revealed an alternative endonuclease-independent (ENi) pathway for L1 retrotransposition. Interestingly, some ENi retrotransposition events in DNA protein kinase catalytic subunit-deficient cells are targeted to dysfunctional telomeres. Here we used an in vitro assay to detect L1 reverse transcriptase activity to demonstrate that wild-type or endonuclease-defective L1 ribonucleoprotein particles can use oligonucleotide adapters that mimic telomeric ends as primers to initiate the reverse transcription of L1 mRNA. Importantly, these ribonucleoprotein particles also contain a nuclease activity that can process the oligonucleotide adapters before the initiation of reverse transcription. Finally, we demonstrate that ORF1p is not strictly required for ENi retrotransposition at dysfunctional telomeres. Thus, these data further highlight similarities between the mechanism of ENi L1 retrotransposition and telomerase. PMID:21940498

Similarities between long interspersed element-1 (LINE-1) reverse transcriptase and telomerase.

PubMed

Kopera, Huira C; Moldovan, John B; Morrish, Tammy A; Garcia-Perez, Jose Luis; Moran, John V

2011-12-20

Long interspersed element-1 (LINE-1 or L1) retrotransposons encode two proteins (ORF1p and ORF2p) that contain activities required for conventional retrotransposition by a mechanism termed target-site primed reverse transcription. Previous experiments in XRCC4 or DNA protein kinase catalytic subunit-deficient CHO cell lines, which are defective for the nonhomologous end-joining DNA repair pathway, revealed an alternative endonuclease-independent (ENi) pathway for L1 retrotransposition. Interestingly, some ENi retrotransposition events in DNA protein kinase catalytic subunit-deficient cells are targeted to dysfunctional telomeres. Here we used an in vitro assay to detect L1 reverse transcriptase activity to demonstrate that wild-type or endonuclease-defective L1 ribonucleoprotein particles can use oligonucleotide adapters that mimic telomeric ends as primers to initiate the reverse transcription of L1 mRNA. Importantly, these ribonucleoprotein particles also contain a nuclease activity that can process the oligonucleotide adapters before the initiation of reverse transcription. Finally, we demonstrate that ORF1p is not strictly required for ENi retrotransposition at dysfunctional telomeres. Thus, these data further highlight similarities between the mechanism of ENi L1 retrotransposition and telomerase.

Development of Reverse Transcription Thermostable Helicase-Dependent DNA Amplification for the Detection of Tomato Spotted Wilt Virus.

PubMed

Wu, Xinghai; Chen, Chanfa; Xiao, Xizhi; Deng, Ming Jun

2016-11-01

A protocol for the reverse transcription-helicase-dependent amplification (RT-HDA) of isothermal DNA was developed for the detection of tomato spotted wilt virus (TSWV). Specific primers, which were based on the highly conserved region of the N gene sequence in TSWV, were used for the amplification of virus's RNA. The LOD of RT-HDA, reverse transcriptase-loop-mediated isothermal amplification (RT-LAMP), and reverse transcriptase-polymerase chain reaction (RT-PCR) assays were conducted using 10-fold serial dilution of RNA eluates. TSWV sensitivity in RT-HDA and RT-LAMP was 4 pg RNA compared with 40 pg RNA in RT-PCR. The specificity of RT-HDA for TSWV was high, showing no cross-reactivity with other tomato and Tospovirus viruses including cucumber mosaic virus (CMV), tomato black ring virus (TBRV), tomato mosaic virus (ToMV), or impatiens necrotic spot virus (INSV). The RT-HDA method is effective for the detection of TSWV in plant samples and is a potential tool for early and rapid detection of TSWV.

Mutations in the S gene and in the overlapping reverse transcriptase region in chronic hepatitis B Chinese patients with coexistence of HBsAg and anti-HBs.

PubMed

Ding, Feng; Miao, Xi-Li; Li, Yan-Xia; Dai, Jin-Fen; Yu, Hong-Gang

2016-01-01

The mechanism underlying the coexistence of hepatitis B surface antigen and antibodies to HBsAg in chronic hepatitis B patients remains unknown. This research aimed to determine the clinical and virological features of the rare pattern. A total of 32 chronic hepatitis B patients infected by HBV genotype C were included: 15 carrying both HBsAg and anti-HBs (group I) and 17 solely positive for HBsAg (group II). S gene and reverse transcriptase region sequences were amplified, sequenced and compared with the reference sequences. The amino acid variability within major hydrophilic region, especially the "a" determinant region, and within reverse transcriptase for regions overlapping the major hydrophilic region in group I is significantly higher than those in group II. Mutation sI126S/T within the "a" determinant was the most frequent change, and only patients from group I had the sQ129R, sG130N, sF134I, sG145R amino acid changes, which are known to alter immunogenicity. In chronic patients, the concurrent HBsAg/anti-HBs serological profile is associated with an increased aa variability in several key areas of HBV genome. Additional research on these genetic mutants are needed to clarify their biological significance for viral persistence. Copyright © 2015 Elsevier Editora Ltda. All rights reserved.

Trends of drug-resistance-associated mutations in the reverse transcriptase gene of HIV type 1 isolates from North India.

PubMed

Azam, Mohd; Malik, Abida; Rizvi, Meher; Rai, Arvind

2014-04-01

A major cause of failure of antiretroviral therapy (ART) is the presence of drug-resistance-associated mutations in the polymerase gene of HIV-1. The paucity of data regarding potential drug resistance to reverse transcriptase inhibitors (RTIs) prompted us to carry out this study. This information will shed light on the extent of drug resistance already present in HIV strains and will give future directions in patient treatment and in drug design. Drug resistance genotyping of a partial reverse transcriptase gene was done in 103 HIV-1-infected patients, including the ART-naive and ART-experienced population. The drug resistance pattern was analyzed using the Stanford HIV-DR database, the IAS-USA mutation list and the REGA algorithm-v8.0. Subtyping was done using the REGA HIV-1 subtyping tool-v2.01. The majority of our sequences (96 %) were found to be subtype C, and four (3.8 %) were subtype A1. Significant prevalence of DR mutations (28 %) was observed in the RT gene. Major amino acid substitutions were seen at positions 41, 90, 98, 103, 106, 108, 138, 181, 184, 190, 215, and 219, which confer high/intermediate levels of resistance to most RTIs, independently or together. Our results show that there is an urgent need to tailor ART drug regimens to the individual to achieve optimum therapeutic outcome in North India.

Telomerase reverse transcriptase (TERT) - enhancer of zeste homolog 2 (EZH2) network regulates lipid metabolism and DNA damage responses in glioblastoma.

PubMed

Ahmad, Fahim; Patrick, Shruti; Sheikh, Touseef; Sharma, Vikas; Pathak, Pankaj; Malgulwar, Prit Benny; Kumar, Anupam; Joshi, Shanker Datt; Sarkar, Chitra; Sen, Ellora

2017-12-01

Elevated expression of enhancer of zeste homolog 2 (EZH2), a histone H3K27 methyltransferase, was observed in gliomas harboring telomerase reverse transcriptase (TERT) promoter mutations. Given the known involvement of TERT and EZH2 in glioma progression, the correlation between the two and subsequently its involvement in metabolic programming was investigated. Inhibition of human telomerase reverse transcriptase either pharmacologically or through genetic manipulation not only decreased EZH2 expression, but also (i) abrogated FASN levels, (ii) decreased de novo fatty acid accumulation, and (iii) increased ataxia-telangiectasia-mutated (ATM) phosphorylation levels. Conversely, diminished TERT and FASN levels upon siRNA-mediated EZH2 knockdown indicated a positive correlation between TERT and EZH2. Interestingly, ATM kinase inhibitor rescued TERT inhibition-mediated decrease in FASN and EZH2 levels. Importantly, TERT promoter mutant tumors exhibited greater microsatellite instability, heightened FASN levels and lipid accumulation. Coherent with in vitro findings, pharmacological inhibition of TERT by costunolide decreased lipid accumulation and elevated ATM expression in heterotypic xenograft glioma mouse model. By bringing TERT-EZH2 network at the forefront as driver of dysregulated metabolism, our findings highlight the non-canonical but distinct role of TERT in metabolic reprogramming and DNA damage responses in glioblastoma. © 2017 International Society for Neurochemistry.

Lower genetic variability of HIV-1 and antiretroviral drug resistance in pregnant women from the state of Pará, Brazil.

PubMed

Machado, Luiz Fernando Almeida; Costa, Iran Barros; Folha, Maria Nazaré; da Luz, Anderson Levy Bessa; Vallinoto, Antonio Carlos Rosário; Ishak, Ricardo; Ishak, Marluisa Oliveira Guimarães

2017-04-12

The present study aimed to describe the genetic diversity of HIV-1, as well as the resistance profile of the viruses identified in HIV-1 infected pregnant women under antiretroviral therapy in the state of Pará, Northern Brazil. Blood samples were collected from 45 HIV-1 infected pregnant to determine the virus subtypes according to the HIV-1 protease (PR) gene and part of the HIV-1 reverse transcriptase (RT) gene by sequencing the nucleotides of these regions. Drug resistance mutations and susceptibility to antiretroviral drugs were analyzed by the Stanford HIV Drug Resistance Database. Out of 45 samples, only 34 could be amplified for PR and 30 for RT. Regarding the PR gene, subtypes B (97.1%) and C (2.9%) were identified; for the RT gene, subtypes B (90.0%), F (6.7%), and C (3.3%) were detected. Resistance to protease inhibitors (PI) was identified in 5.8% of the pregnant, and mutations conferring resistance to nucleoside reverse transcriptase inhibitors were found in 3.3%, while mutations conferring resistance to non-nucleoside reverse transcriptase inhibitors were found in 3.3%. These results showed a low frequency of strains resistant to antiretroviral drugs, the prevalence of subtypes B and F, and the persistent low transmission of subtype C in pregnant of the state of Pará, Brazil.

Comprehensive phylogenetic analysis of bacterial reverse transcriptases.

PubMed

Toro, Nicolás; Nisa-Martínez, Rafael

2014-01-01

Much less is known about reverse transcriptases (RTs) in prokaryotes than in eukaryotes, with most prokaryotic enzymes still uncharacterized. Two surveys involving BLAST searches for RT genes in prokaryotic genomes revealed the presence of large numbers of diverse, uncharacterized RTs and RT-like sequences. Here, using consistent annotation across all sequenced bacterial species from GenBank and other sources via RAST, available from the PATRIC (Pathogenic Resource Integration Center) platform, we have compiled the data for currently annotated reverse transcriptases from completely sequenced bacterial genomes. RT sequences are broadly distributed across bacterial phyla, but green sulfur bacteria and cyanobacteria have the highest levels of RT sequence diversity (≤85% identity) per genome. By contrast, phylum Actinobacteria, for which a large number of genomes have been sequenced, was found to have a low RT sequence diversity. Phylogenetic analyses revealed that bacterial RTs could be classified into 17 main groups: group II introns, retrons/retron-like RTs, diversity-generating retroelements (DGRs), Abi-like RTs, CRISPR-Cas-associated RTs, group II-like RTs (G2L), and 11 other groups of RTs of unknown function. Proteobacteria had the highest potential functional diversity, as they possessed most of the RT groups. Group II introns and DGRs were the most widely distributed RTs in bacterial phyla. Our results provide insights into bacterial RT phylogeny and the basis for an update of annotation systems based on sequence/domain homology.

Comprehensive Phylogenetic Analysis of Bacterial Reverse Transcriptases

PubMed Central

Toro, Nicolás; Nisa-Martínez, Rafael

2014-01-01

Much less is known about reverse transcriptases (RTs) in prokaryotes than in eukaryotes, with most prokaryotic enzymes still uncharacterized. Two surveys involving BLAST searches for RT genes in prokaryotic genomes revealed the presence of large numbers of diverse, uncharacterized RTs and RT-like sequences. Here, using consistent annotation across all sequenced bacterial species from GenBank and other sources via RAST, available from the PATRIC (Pathogenic Resource Integration Center) platform, we have compiled the data for currently annotated reverse transcriptases from completely sequenced bacterial genomes. RT sequences are broadly distributed across bacterial phyla, but green sulfur bacteria and cyanobacteria have the highest levels of RT sequence diversity (≤85% identity) per genome. By contrast, phylum Actinobacteria, for which a large number of genomes have been sequenced, was found to have a low RT sequence diversity. Phylogenetic analyses revealed that bacterial RTs could be classified into 17 main groups: group II introns, retrons/retron-like RTs, diversity-generating retroelements (DGRs), Abi-like RTs, CRISPR-Cas-associated RTs, group II-like RTs (G2L), and 11 other groups of RTs of unknown function. Proteobacteria had the highest potential functional diversity, as they possessed most of the RT groups. Group II introns and DGRs were the most widely distributed RTs in bacterial phyla. Our results provide insights into bacterial RT phylogeny and the basis for an update of annotation systems based on sequence/domain homology. PMID:25423096

Leishmanicidal and cytotoxic activity from plants used in Tacana traditional medicine (Bolivia).

PubMed

Arévalo-Lopéz, Diandra; Nina, Nélida; Ticona, Juan C; Limachi, Ivan; Salamanca, Efrain; Udaeta, Enrique; Paredes, Crispin; Espinoza, Boris; Serato, Alcides; Garnica, David; Limachi, Abigail; Coaquira, Dayana; Salazar, Sarah; Flores, Ninoska; Sterner, Olov; Giménez, Alberto

2018-04-24

Thirty-eight Tacana medicinal plant species used to treat skin problems, including leishmania ulcers, skin infections, inflammation and wound healing, were collected in the community of Buena Vista, Bolivia, with the Tacana people. Twenty two species are documented for the first time as medicinal plants for this ethnic group living in the northern area of the Department of La Paz. To evaluate the leishmanicidal effect (IC 50 ) and cytotoxicity (LD 50 ) of the selected plants. To carry out bioguided studies on the active extracts. To assess the potential of Bolivian plant biodiversity associated with traditional knowledge in the discovery of alternative sources to fight leishmaniasis. Seventy three ethanol extracts were prepared from 38 species by maceration and were evaluated in vitro against promastigotes of Leishmania amazonensis and L. braziliensis. Active extracts (IC 50 ≤ 50 μg/mL) were fractionated by chromatography on Silica gel column and the fractions were assessed against the two Leishmania strains. The most active fractions and the crude extracts were evaluated against reference strains of L. amazonensis, L. braziliensis, L. aethiopica, two native strains (L. Lainsoni and L. braziliensis) and for cytotoxicity against HeLa cells. The chromatographic profile of the active fractions was obtained by reverse phase chromatography using HPLC. From the 73 extracts, 39 extracts (53.4%) were inactive and 34 showed activity. Thirteen species were sselected for bioguided studies. The crude extracts and their 36 fractions were evaluated against two Leishmania strains. The most active fraction were tested in a panel of five leishmania strains and for cytotoxicity. The Selective Index (SI = LD 50 /IC 50 ) was calculated, and were generally low. Retention time and UV spectra were recorded for the active fractions by HPLC-DAD using a reverse phase column. Profiles were very different from each other, showing the presence of different compounds. Bolivian traditional knowledge from the Tacanba was useful to identify plants with effect on Leishmania promastigotes. Chromatographic bioguided studies showed stronger leishmanicidal and cytotoxic activity for the medium polar fraction. HPLC analysis showed different chromatographic profiles of the active fractions. Copyright © 2018 Elsevier B.V. All rights reserved.

The conserved N-terminal basic residues and zinc-finger motifs of HIV-1 nucleocapsid restrict the viral cDNA synthesis during virus formation and maturation

PubMed Central

Didierlaurent, Ludovic; Houzet, Laurent; Morichaud, Zakia; Darlix, Jean-Luc; Mougel, Marylène

2008-01-01

Reverse transcription of the genomic RNA by reverse transcriptase occurs soon after HIV-1 infection of target cells. The viral nucleocapsid (NC) protein chaperones this process via its nucleic acid annealing activities and its interactions with the reverse transcriptase enzyme. To function, NC needs its two conserved zinc fingers and flanking basic residues. We recently reported a new role for NC, whereby it negatively controls reverse transcription in the course of virus formation. Indeed, deleting its zinc fingers causes reverse transcription activation in virus producer cells. To investigate this new NC function, we used viruses with subtle mutations in the conserved zinc fingers and its flanking domains. We monitored by quantitative PCR the HIV-1 DNA content in producer cells and in produced virions. Results showed that the two intact zinc-finger structures are required for the temporal control of reverse transcription by NC throughout the virus replication cycle. The N-terminal basic residues also contributed to this new role of NC, while Pro-31 residue between the zinc fingers and Lys-59 in the C-terminal region did not. These findings further highlight the importance of NC as a major target for anti-HIV-1 drugs. PMID:18641038

Inhibition of Human and Rat Sucrase and Maltase Activities To Assess Antiglycemic Potential: Optimization of the Assay Using Acarbose and Polyphenols.

PubMed

Pyner, Alison; Nyambe-Silavwe, Hilda; Williamson, Gary

2017-10-04

We optimized the assays used to measure inhibition of rat and human α-glucosidases (sucrase and maltase activities), intestinal enzymes which catalyze the final steps of carbohydrate digestion. Cell-free extracts from fully differentiated intestinal Caco-2/TC7 monolayers were shown to be a suitable source of sucrase-isomaltase, with the same sequence as human small intestine, and were compared to a rat intestinal extract. The kinetic conditions of the assay were optimized, including comparison of enzymatic and chromatographic methods to detect the monosaccharide products. Human sucrase activity was more susceptible than the rat enzyme to inhibition by acarbose (IC 50 (concentration required for 50% inhibition) = 2.5 ± 0.5 and 12.3 ± 0.6 μM, respectively), by a polyphenol-rich green tea extract, and by pure (-)-epigallocatechin gallate (EGCG) (IC 50 = 657 ± 150 and 950 ± 86 μM respectively). In contrast, the reverse was observed when assessing maltase activity (e.g. IC 50 = 677 ± 241 and 14.0 ± 2.0 μM for human and rat maltase, respectively). 5-Caffeoylquinic acid did not significantly inhibit maltase and was only a very weak inhibitor of sucrase. The data show that for sucrase and maltase activities, inhibition patterns of rat and human enzymes are generally qualitatively similar but can be quantitatively different.

Characterization of acetylcholinesterase-inhibition by itopride.

PubMed

Iwanaga, Y; Kimura, T; Miyashita, N; Morikawa, K; Nagata, O; Itoh, Z; Kondo, Y

1994-11-01

Itopride is a gastroprokinetic benzamide derivative. This agent inhibited both electric eel acetylcholinesterase (AChE) and horse serum butyrylcholinesterase (BuChE). The IC50 of itopride with AChE (2.04 +/- 0.27 microM) was, however, 100-fold less than that with BuChE, whereas in the case of neostigmine with AChE (11.3 +/- 3.4 nM), it was 10-fold less. The recovery of AChE activity inhibited by 10(-7) M neostigmine was partial, but that inhibited by up to 3 x 10(-5) M itopride was complete when the reaction mixture was subjected to ultrafiltration. Double reciprocal plots of the experimental data showed that both Km and Vmax were affected by itopride, suggesting that the inhibition is a "mixed" type, although primarily being an uncompetitive one. The inhibitory effect of itopride on cholinesterase (ChE) activity in guinea pig gastrointestine was much weaker than that on pure AChE. However, in the presence of a low dose of diisopropyl fluorophosphate, just enough to inhibit BuChE but not AChE, the IC50s of itopride against ChE activities were found to be about 0.5 microM. In conclusion, itopride exerts reversible and a "mixed" type of inhibition preferably against AChE. The IC50 of itopride for electric eel and guinea pig gastrointestinal AChE inhibition was 200 times and 50 times as large as that of neostigmine, respectively.

Deregulation of the telomerase reverse transcriptase (TERT) gene by chromosomal translocations in B-cell malignancies.

PubMed

Nagel, Inga; Szczepanowski, Monika; Martín-Subero, José I; Harder, Lana; Akasaka, Takashi; Ammerpohl, Ole; Callet-Bauchu, Evelyne; Gascoyne, Randy D; Gesk, Stefan; Horsman, Doug; Klapper, Wolfram; Majid, Aneela; Martinez-Climent, José A; Stilgenbauer, Stephan; Tönnies, Holger; Dyer, Martin J S; Siebert, Reiner

2010-08-26

Sequence variants at the TERT-CLPTM1L locus in chromosome 5p have been recently associated with disposition for various cancers. Here we show that this locus including the gene encoding the telomerase reverse-transcriptase TERT at 5p13.33 is rarely but recurrently targeted by somatic chromosomal translocations to IGH and non-IG loci in B-cell neoplasms, including acute lymphoblastic leukemia, chronic lymphocytic leukemia, mantle cell lymphoma and splenic marginal zone lymphoma. In addition, cases with genomic amplification of TERT locus were identified. Tumors bearing chromosomal aberrations involving TERT showed higher TERT transcriptional expression and increased telomerase activity. These data suggest that deregulation of TERT gene by chromosomal abnormalities leading to increased telomerase activity might contribute to B-cell lymphomagenesis.

Differential Regulation of Telomerase Reverse Transcriptase Promoter Activation and Protein Degradation by Histone Deacetylase Inhibition.

PubMed

Qing, Hua; Aono, Jun; Findeisen, Hannes M; Jones, Karrie L; Heywood, Elizabeth B; Bruemmer, Dennis

2016-06-01

Telomerase reverse transcriptase (TERT) maintains telomeres and is rate limiting for replicative life span. While most somatic tissues silence TERT transcription resulting in telomere shortening, cells derived from cancer or cardiovascular diseases express TERT and activate telomerase. In the present study, we demonstrate that histone deacetylase (HDAC) inhibition induces TERT transcription and promoter activation. At the protein level in contrast, HDAC inhibition decreases TERT protein abundance through enhanced degradation, which decreases telomerase activity and induces senescence. Finally, we demonstrate that HDAC inhibition decreases TERT expression during vascular remodeling in vivo. These data illustrate a differential regulation of TERT transcription and protein stability by HDAC inhibition and suggest that TERT may constitute an important target for the anti-proliferative efficacy of HDAC inhibitors. © 2015 Wiley Periodicals, Inc.

Hepatotoxicity of nucleoside reverse transcriptase inhibitors.

PubMed

Montessori, Valentina; Harris, Marianne; Montaner, Julio S G

2003-05-01

Hepatotoxicity is an adverse effect of all available classes of antiretrovirals, including nucleoside reverse transcriptase inhibitors (NRTI). A syndrome of hepatic steatosis and lactic acidosis has been recognized as a rare, potentially fatal complication since the advent of NRTI monotherapy in the early 1990s. Today, NRTI remain the backbone of antiretroviral combination regimens, and, with the success of current treatment strategies, exposure to two or more of these agents may occur over a number of years. Hepatic steatosis and lactic acidosis are accordingly being observed more frequently, along with a more recently recognized syndrome of chronic hyperlactatemia. These as well as other adverse effects of NRTI are mediated by inhibition of human DNA polymerase gamma, resulting in mitochondrial dysfunction in the liver and other tissues. Early recognition and intervention are essential to avert serious outcomes.

Herpes Simplex Virus Type 2 Suppressive Therapy with Acyclovir or Valacyclovir Does Not Select for Specific HIV-1 Resistance in HIV-1/HSV-2 Dually Infected Persons

PubMed Central

Lingappa, Jairam; Beck, Ingrid; Frenkel, Lisa M.; Pepper, Gregory; Celum, Connie; Wald, Anna; Fife, Kenneth H.; Were, Edwin; Mugo, Nelly; Sanchez, Jorge; Essex, Myron; Makhema, Joseph; Kiarie, James; Farquhar, Carey; Corey, Lawrence

2011-01-01

Recent in vitro studies suggest that acyclovir may directly inhibit HIV-1 replication and can select for a specific HIV-1 reverse transcriptase mutation (V75I) with concomitant loss of an anti-HIV-1 effect. We tested for HIV-1 genotypic resistance at reverse transcriptase codon 75 in plasma from 168 HIV-1–infected persons from Botswana, Kenya, Peru, and the United States taking daily acyclovir or valacyclovir for between 8 weeks and 24 months. No V75I cases were detected (95% confidence interval, 0%–2.2%). These prospective in vivo studies suggest that standard-dose acyclovir or valacyclovir does not select for HIV-1 resistance. PMID:21148504

Evaluation of bisindole as potent β-glucuronidase inhibitors: synthesis and in silico based studies.

PubMed

Khan, Khalid Mohammed; Rahim, Fazal; Wadood, Abdul; Taha, Muhammad; Khan, Momin; Naureen, Shagufta; Ambreen, Nida; Hussain, Shafqat; Perveen, Shahnaz; Choudhary, Mohammad Iqbal

2014-04-01

Bisindole analogs 1-17 were synthesized and evaluated for their in vitro β-glucuronidase inhibitory potential. Out of seventeen compounds, the analog 1 (IC50=1.62±0.04 μM), 6 (IC50=1.86±0.05 μM), 10 (IC50=2.80±0.29 μM), 9 (IC50=3.10±0.28 μM), 14 (IC50=4.30±0.08 μM), 2 (IC50=18.40±0.09 μM), 19 (IC50=19.90±1.05 μM), 4 (IC50=20.90±0.62 μM), 7 (IC50=21.50±0.77 μM), and 3 (IC50=22.30±0.02 μM) showed superior β-glucuronidase inhibitory activity than the standard (d-saccharic acid 1,4-lactone, IC50=48.40±1.25 μM). In addition, molecular docking studies were performed to investigate the binding interactions of bisindole derivatives with the enzyme. This study has identified a new class of potent β-glucouronidase inhibitors. Copyright © 2014 Elsevier Ltd. All rights reserved.

Natural products as sources of new lead compounds for the treatment of Alzheimer's disease.

PubMed

Huang, Ling; Su, Tao; Li, Xingshu

2013-01-01

Alzheimer's disease (AD) is the most prevalent form of dementia and affects approximately 24 million people worldwide. One possible approach for the treatment of this disease is the restoration of the level of acetylcholine (ACh) through the inhibition of acetylcholinesterase (AChE) with reversible inhibitors. Naturally occurring alkaloids are an important source of AChE inhibitors. Galantamine and huperzine A have been used for the clinical treatment of AD patients. In this review, we summarise the natural products and their derivatives that were reported to act as AChE inhibitors for the treatment of AD in 2010-2013. Several characteristics were summarised from the literature results: 1) Amongst all of the natural products with AChE inhibitory activity, alkaloids appear to be the most promising compound class. 2) Coumarins, flavonoids, stilbenes, and other natural products are also important AChE inhibitors from natural products. Among these inhibitors, 146 (IC50 = 0.573 µM) was identified as the most potent AChE inhibitor. 3) A coumarin derivative (117, IC50 = 0.11 nM) exhibited more than 100-fold superior activity compared with the reference drug donepezil hydrochloride (IC50 = 14 nM). In conclusion, natural products and their derivatives are promising leads for the development of new drugs for the future treatment of AD.

Discovery of novel alkylated (bis)urea and (bis)thiourea polyamine analogues with potent antimalarial activities.

PubMed

Verlinden, Bianca K; Niemand, Jandeli; Snyman, Janette; Sharma, Shiv K; Beattie, Ross J; Woster, Patrick M; Birkholtz, Lyn-Marie

2011-10-13

A series of alkylated (bis)urea and (bis)thiourea polyamine analogues were synthesized and screened for antimalarial activity against chloroquine-sensitive and -resistant strains of Plasmodium falciparum in vitro. All analogues showed growth inhibitory activity against P. falciparum at less than 3 μM, with the majority having effective IC(50) values in the 100-650 nM range. Analogues arrested parasitic growth within 24 h of exposure due to a block in nuclear division and therefore asexual development. Moreover, this effect appears to be cytotoxic and highly selective to malaria parasites (>7000-fold lower IC(50) against P. falciparum) and is not reversible by the exogenous addition of polyamines. With this first report of potent antimalarial activity of polyamine analogues containing 3-7-3 or 3-6-3 carbon backbones and substituted terminal urea- or thiourea moieties, we propose that these compounds represent a structurally novel class of antimalarial agents.

Inhibitory effect of ebselen on cerebral acetylcholinesterase activity in vitro: kinetics and reversibility of inhibition.

PubMed

Martini, Franciele; Bruning, César Augusto; Soares, Suelen Mendonca; Nogueira, Cristina Wayne; Zeni, Gilson

2015-01-01

Ebselen is a synthetic organoselenium compound that has been considered a potential pharmacological agent with low toxicity, showing antioxidant, anti-inflammatory and neuroprotective effects. It is bioavailable, blood-brain barrier permeant and safe based on cellular toxicity and Phase I-III clinical trials. There is evidence that ebselen inhibits acetylcholinesterase (AChE) activity, an enzyme that plays a key role in the cholinergic system by hydrolyzing acetylcholine (ACh), in vitro and ex vivo. This system has a well-known relationship with cognitive process, and AChE inhibitors, such as donepezil and galantamine, have been used to treat cognitive deficits, mainly in the Alzheimer's Disease (AD). However, these drugs have poor bioavailability and a number of side effects, including gastrointestinal upsets and hepatotoxicity. In this way, this study aimed to evaluate the effect of ebselen on cerebral AChE activity in vitro and to determine the kinetic profile and the reversibility of inhibition by dialysis. Ebselen inhibited the cerebral AChE activity with an IC50 of 29 µM, similar to IC50 found with pure AChE from electric eel, demonstrating a mixed and reversible inhibition of AChE, since it increased Km and decreased Vmax. The AChE activity was recovered within 60 min of dialysis. Therefore, the use of ebselen as a therapeutic agent for treatment of AD should be considered, although memory behavior tasks are needed to support such hypothesis.

Peptides from puff adder Bitis arietans venom, novel inhibitors of nicotinic acetylcholine receptors.

PubMed

Vulfius, Catherine A; Spirova, Ekaterina N; Serebryakova, Marina V; Shelukhina, Irina V; Kudryavtsev, Denis S; Kryukova, Elena V; Starkov, Vladislav G; Kopylova, Nina V; Zhmak, Maxim N; Ivanov, Igor A; Kudryashova, Ksenia S; Andreeva, Tatyana V; Tsetlin, Victor I; Utkin, Yuri N

2016-10-01

Phospholipase A 2 (named bitanarin) possessing capability to block nicotinic acetylcholine receptors (nAChRs) was isolated earlier (Vulfius et al., 2011) from puff adder Bitis arietans venom. Further studies indicated that low molecular weight fractions of puff adder venom inhibit nAChRs as well. In this paper, we report on isolation from this venom and characterization of three novel peptides called baptides 1, 2 and 3 that reversibly block nAChRs. To isolate the peptides, the venom of B. arietans was fractionated by gel-filtration and reversed phase chromatography. The amino acid sequences of peptides were established by de novo sequencing using MALDI mass spectrometry. Baptide 1 comprised 7, baptides 2 and 3-10 amino acid residues, the latter being acetylated at the N-terminus. This is the first indication for the presence of such post-translational modification in snake venom proteins. None of the peptides contain cysteine residues. For biological activity studies the peptides were prepared by solid phase peptide synthesis. Baptide 3 and 2 blocked acetylcholine-elicited currents in isolated Lymnaea stagnalis neurons with IC 50 of about 50 μM and 250 μM, respectively. In addition baptide 2 blocked acetylcholine-induced currents in muscle nAChR heterologously expressed in Xenopus oocytes with IC 50 of about 3 μM. The peptides did not compete with radioactive α-bungarotoxin for binding to Torpedo and α7 nAChRs at concentration up to 200 μM that suggests non-competitive mode of inhibition. Calcium imaging studies on α7 and muscle nAChRs heterologously expressed in mouse neuroblastoma Neuro2a cells showed that on α7 receptor baptide 2 inhibited acetylcholine-induced increasing intracellular calcium concentration with IC 50 of 20.6 ± 3.93 μM. On both α7 and muscle nAChRs the suppression of maximal response to acetylcholine by about 50% was observed at baptide 2 concentration of 25 μM, the value being close to IC 50 on α7 nAChR. These data are in accord with non-competitive inhibition as follows from α-bungarotoxin binding experiments. The described peptides are the shortest peptides without disulfide bridges isolated from animal venom and capable to inhibit nAChR by non-competitive way. Copyright © 2016. Published by Elsevier Ltd.

Plastid, nuclear and reverse transcriptase sequences in the mitochondrial genome of Oenothera: is genetic information transferred between organelles via RNA?

PubMed Central

Schuster, W; Brennicke, A

1987-01-01

We describe an open reading frame (ORF) with high homology to reverse transcriptase in the mitochondrial genome of Oenothera. This ORF displays all the characteristics of an active plant mitochondrial gene with a possible ribosome binding site and 39% T in the third codon position. It is located between a sequence fragment from the plastid genome and one of nuclear origin downstream from the gene encoding subunit 5 of the NADH dehydrogenase. The nuclear derived sequence consists of 528 nucleotides from the small ribosomal RNA and contains an expansion segment unique to nuclear rRNAs. The plastid sequence contains part of the ribosomal protein S4 and the complete tRNA(Ser). The observation that only transcribed sequences have been found i more than one subcellular compartment in higher plants suggests that interorganellar transfer of genetic information may occur via RNA and subsequent local reverse transcription and genomic integration. PMID:14650433

Antiretroviral therapy for human immunodeficiency virus infection in 1997.

PubMed Central

Katzenstein, D A

1997-01-01

It has become clear that the acquired immunodeficiency syndrome follows continuous replication of the human immunodeficiency virus (HIV) and a decrease in immune capability, most obviously a decline in the number of CD4 lymphocytes. An understanding of key elements in the infectious life cycle of HIV has led to the development of potent antiretroviral drugs selectively targeting unique reverse transcriptase and protease enzymes of the virus. Completed clinical trials have shown that antiretroviral therapy for HIV infection, begun early, reduces viral replication and reverses the decline in CD4 lymphocyte numbers. Recent studies of combination therapies have shown that decreases in plasma HIV viremia to low levels and sustained increases in CD4 cell numbers are associated with longer survival. Potent combination regimens including protease inhibitors and non-nucleoside reverse transcriptase inhibitors suppress detectable viral replication and have demonstrated clinical benefits in patients with advanced disease. Progress in antiretroviral therapy and methods to monitor responses to treatment are providing new hope in the treatment of HIV infection. PMID:9217434

HIV/AIDS Medicines

MedlinePlus

... few years. But today, there are many effective medicines to fight the infection, and people with HIV ... healthier lives. There are five major types of medicines: Reverse transcriptase (RT) inhibitors - interfere with a critical ...

Inhibition of the NF-κB signaling pathway by the curcumin analog, 3,5-Bis(2-pyridinylmethylidene)-4-piperidone (EF31): anti-inflammatory and anti-cancer properties

PubMed Central

Olivera, Anlys; Moore, Terry W.; Hu, Fang; Brown, Andrew P.; Sun, Aiming; Liotta, Dennis C.; Snyder, James P.; Yoon, Younghyoun; Shim, Hyunsuk; Marcus, Adam I.; Miller, Andrew H.; Pace, Thaddeus W. W.

2012-01-01

Nuclear factor kappa B (NF-κB) is a key signaling molecule in the elaboration of the inflammatory response. Data indicate that curcumin, a natural ingredient of the curry spice turmeric, acts as a NF-κB inhibitor and exhibits both anti-inflammatory and anti-cancer properties. Curcumin analogues with enhanced activity on the NF-κB and other inflammatory signaling pathways have been developed including the synthetic monoketone compound termed 3,5-Bis(2-fluorobenzylidene)-4-piperidone (EF24). 3,5-Bis(2-pyridinylmethylidene)-4-piperidone (EF31) is a structurally-related curcumin analogue whose potency for NF-κB inhibition has yet to be determined. To examine the activity of EF31 compared to EF24 and curcumin, mouse RAW264.7 macrophages were treated with EF31, EF24, curcumin (1–100µM) or vehicle (DMSO 1%) for 1 hour. NF-κB pathway activity was assessed following treatment with lipopolysaccharide (LPS) (1µg/mL). EF31 (IC50 ~5µM) exhibited significantly more potent inhibition of LPS-induced NF-κB DNA binding compared to both EF24 (IC50~35µM) and curcumin (IC50 >50µM). In addition, EF31 exhibited significantly greater inhibition of NF-κB nuclear translocation as well as the induction of downstream inflammatory mediators including pro-inflammatory cytokine mRNA and protein (tumor necrosis factor-α, interleukin-1β, and interleukin-6). Regarding the mechanism of these effects on NF-κB activity, EF31 (IC50~1.92µM) exhibited significantly greater inhibition of IκB kinase β compared to EF24 (IC50~131µM). Finally, EF31 demonstrated potent toxicity in NF-κB-dependent cancer cell lines while having minimal and reversible toxicity in RAW264.7 macrophages. These data indicate that EF31 is a more potent inhibitor of NF-κB activity than either EF24 or curcumin while exhibiting both anti-inflammatory and anticancer activities. Thus, EF31 represents a promising curcumin analogue for further therapeutic development. PMID:22197802

Inhibition of the NF-κB signaling pathway by the curcumin analog, 3,5-Bis(2-pyridinylmethylidene)-4-piperidone (EF31): anti-inflammatory and anti-cancer properties.

PubMed

Olivera, Anlys; Moore, Terry W; Hu, Fang; Brown, Andrew P; Sun, Aiming; Liotta, Dennis C; Snyder, James P; Yoon, Younghyoun; Shim, Hyunsuk; Marcus, Adam I; Miller, Andrew H; Pace, Thaddeus W W

2012-02-01

Nuclear factor kappa B (NF-κB) is a key signaling molecule in the elaboration of the inflammatory response. Data indicate that curcumin, a natural ingredient of the curry spice turmeric, acts as a NF-κB inhibitor and exhibits both anti-inflammatory and anti-cancer properties. Curcumin analogs with enhanced activity on NF-κB and other inflammatory signaling pathways have been developed including the synthetic monoketone compound 3,5-Bis(2-fluorobenzylidene)-4-piperidone (EF24). 3,5-Bis(2-pyridinylmethylidene)-4-piperidone (EF31) is a structurally-related curcumin analog whose potency for NF-κB inhibition has yet to be determined. To examine the activity of EF31 compared to EF24 and curcumin, mouse RAW264.7 macrophages were treated with EF31, EF24, curcumin (1-100 μM) or vehicle (DMSO 1%) for 1h. NF-κB pathway activity was assessed following treatment with lipopolysaccharide (LPS) (1 μg/mL). EF31 (IC(50)~5 μM) exhibited significantly more potent inhibition of LPS-induced NF-κB DNA binding compared to both EF24 (IC(50)~35 μM) and curcumin (IC(50) >50 μM). In addition, EF31 exhibited greater inhibition of NF-κB nuclear translocation as well as the induction of downstream inflammatory mediators including pro-inflammatory cytokine mRNA and protein (tumor necrosis factor-α, interleukin-1β, and interleukin-6). Regarding the mechanism of these effects on NF-κB, EF31 (IC(50)~1.92 μM) exhibited significantly greater inhibition of IκB kinase β compared to EF24 (IC(50)~131 μM). Finally, EF31 demonstrated potent toxicity in NF-κB-dependent cancer cell lines while having minimal and reversible toxicity in RAW264.7 macrophages. These data indicate that EF31 is a more potent inhibitor of NF-κB activity than either EF24 or curcumin while exhibiting both anti-inflammatory and anticancer activities. Thus, EF31 represents a promising curcumin analog for further therapeutic development. Copyright © 2011 Elsevier B.V. All rights reserved.

Expression of TGF-beta1, osteonectin, and BMP-4 in mandibular distraction osteogenesis with compression stimulation: reverse transcriptase-polymerase chain reaction study and biomechanical test.

PubMed

Kim, Uk-Kyu; Park, Seong-Jin; Seong, Wook-Jin; Heo, Jun; Hwang, Dae-Seok; Kim, Yong-Deok; Shin, Sang-Hun; Kim, Gyoo-Cheon

2010-09-01

This study compared the levels of transforming growth factor-beta1 (TGF-beta1), osteonectin, and bone morphogenetic protein-4 (BMP-4) expression in regenerated bone in a rabbit mandible that had undergone conventional distraction osteogenesis (DO) with those in regenerated bone from a modified DO technique with compression stimulation. A total of 42 rabbits were used in this reverse transcriptase-polymerase chain reaction study. In the control group, distraction was performed at 1 mm/day for 8 days. In the experimental group, overdistraction was performed for 10 days, followed by a 3-day latency period and 2 days of compression to achieve the same amount of DO. Three rabbits per subgroup were killed at 0, 5, 13, 20, 27, 34, and 41 days after the initial osteotomy. The levels of TGF-beta1, osteonectin, and BMP-4 in the bone regenerates were measured by reverse transcriptase-polymerase chain reaction. A biomechanical microhardness test was also performed in 8 rabbits as a separate experiment. Reverse transcriptase-polymerase chain reaction revealed a greater level of TGF-beta1 in the experimental group immediately after applying the compression force that continued for 2 weeks. The level then decreased to that of the control group at 3 weeks. The greater level of osteonectin in the experimental group after compression than that in the control group continued for 3 weeks. In the experimental group, the level of BMP-4 increased immediately after compression. However, the level in the control group decreased. The microhardness ratio of distracted bone to normal bone on the cortex was statistically different at 0.47 in the control group and 0.80 in the experimental group (P = .049) at 55 days after osteotomy. The effectiveness of the new DO technique with compression stimulation was confirmed by the gene expression study and the biomechanical test findings. Copyright 2010 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

GAS5 modulated autophagy is a mechanism modulating cisplatin sensitivity in NSCLC cells.

PubMed

Zhang, N; Yang, G-Q; Shao, X-M; Wei, L

2016-06-01

In this study, we investigated the association between lncRNA GAS5 and cisplatin (DDP) resistance in NSCLC and further studied the regulative effect of GAS5 on autophagy and DDP resistance. GAS5 expression in cancerous and adjacent normal tissues from 15 NSCLC patients received neoadjuvant chemotherapy and the following surgery were measured using qRT-PCR analysis. GAS5 gain-and-loss study was performed using A549 and A549/DDP cells as an in-vitro model to investigate the effect of GAS5 on autophagy and cisplatin sensitivity. NSCLC tissues had a substantially lower expression of GAS5 than adjacent normal tissues. The NSCLC tissues from patients with progressive disease (PD) had even lower GAS5 expression. GAS5 knockdown increased DDP IC50 of A549 cells, while GAS5 overexpression decreased DDP IC50 of A549/DDP cells. A549/DDP cells had significantly higher basal autophagy than A549 cells. GAS5 knockdown resulted in decreased autophagy in A549 cells, while GAS5 overexpression led to increased autophagy in A549/DDP cells. Treatment with 3-MA, an autophagy inhibitor, significantly decreased DDP IC50 and promoted DDP-induced cell apoptosis in A549 cells. In addition, 3-MA also partly reversed the effect of GAS5 knockdown. In A549/DDP cells, GAS5 showed the similar effect as 3-MA in reducing DPP IC50 and promoting DDP-induced apoptosis and also presented synergic effect with 3-MA. GAS5 downregulation is associated with cisplatin resistance in NSCLC. GAS5 can inhibit autophagy and therefore enhance cisplatin sensitivity in NSCLC cells.

Synthesis of novel amides based on acridone scaffold with interesting antineoplastic activity.

PubMed

Mahajan, Anand A; Rane, Rajesh A; Amritkar, Anish A; Naphade, Shital S; Miniyar, Pankaj B; Bangalore, Pavan Kumar; Karpoormath, Rajshekhar

2015-01-01

In search of novel cytotoxic agents based on acridone scaffold, twenty five derivatives of acridone-2- carboxamide were synthesized and evaluated against a panel of eleven cancer cell lines by using MTT assay. Amides, A5 and A8 (IC50 = 0.3 µM) exhibited good cytotoxicity against MCF7. Compound A22 (IC50 = 4.3 µM) was found to be selectively cytotoxic against cancer cell line MCF7 and KB403. Particularly, promising cytotoxic activities were shown by amides A6 (IC50 = 0.7 µM), A16 (IC50 = 6.3 µM), A8 (IC50 = 0.9 µM ), A21 (IC50 = 1.3 µM), A5 (IC50 = 2.9 µM), A8 (IC50 = 2.8 µM), A14 (IC50 = 0.8 µM), A9 (IC50 = 0.8 µM) and A8 (IC50 = 0.4 µM) against cell lines; PA1, WRL68, CaCO2, TK-10, K-562, PC-3, HOP-92, ECV-304 and UACC-257, respectively. The favorable cytotoxic profile and non-toxicity towards normal human cells displayed by the derivative revealed their potential for further anticancer drug developments.

6-Nitrobenzimidazole derivatives: potential phosphodiesterase inhibitors: synthesis and structure-activity relationship.

PubMed

Khan, K M; Shah, Zarbad; Ahmad, V U; Ambreen, N; Khan, M; Taha, M; Rahim, F; Noreen, S; Perveen, S; Choudhary, M I; Voelter, W

2012-02-15

6-Nitrobenzimidazole derivatives (1-30) synthesized and their phosphodiesterase inhibitory activities determined. Out of thirty tested compounds, ten showed a varying degrees of phosphodiesterase inhibition with IC(50) values between 1.5±0.043 and 294.0±16.7 μM. Compounds 30 (IC(50)=1.5±0.043 μM), 1 (IC(50)=2.4±0.049 μM), 11 (IC(50)=5.7±0.113 μM), 13 (IC(50)=6.4±0.148 μM), 14 (IC(50)=10.5±0.51 μM), 9 (IC(50)=11.49±0.08 μM), 3 (IC(50)=63.1±1.48 μM), 10 (IC(50)=120.0±4.47 μM), and 6 (IC(50)=153.2±5.6 μM) showed excellent phosphodiesterase inhibitory activity, much superior to the standard EDTA (IC(50)=274±0.007 μM), and thus are potential molecules for the development of a new class of phosphodiesterase inhibitors. A structure-activity relationship is evaluated. All compounds are characterized by spectroscopic parameters. Copyright © 2011 Elsevier Ltd. All rights reserved.

Development and evaluation of a simple and effective RT-qPCR inhibitory assay for detection of the efficacy of compounds towards HIV reverse transcriptase.

PubMed

Marino-Merlo, Francesca; Frezza, Caterina; Papaianni, Emanuela; Valletta, Elena; Mastino, Antonio; Macchi, Beatrice

2017-11-01

Assessing the actual efficacy of compounds to directly inhibit HIV reverse transcriptase (RT) activity is a main goal in preclinical antiretroviral studies. Our previous studies demonstrated that the effects of inhibitor compounds towards HIV-RT could be efficiently assessed through a simple cell-free assay based on conventional reverse transcription PCR. In the present study, we describe a modified variant of our assay, termed RT real-time quantitative PCR inhibitory assay (RT-qPCR-IA), in which the ability of compounds to restrict the complementary DNA (cDNA) generation by HIV-RT using a specific RNA template is performed by the real-time technique, in order to improve both accuracy and sensitivity of the method. As specific RNA template, RNA extracted from stable transfectants ectopically expressing the herpes simplex virus 1 glycoprotein D gene was utilized. HIV-RT, of both commercial or house-made viral lysate origin, was employed for the assay. To assess the reliability of RT-qPCR-IA, we performed a comparative, quantitative analysis of the dose-dependent effect exerted by known nucleotide and non-nucleotide reverse-transcriptase inhibitors, using the SYBR Green dye chemistry as detection system. The results obtained with RT-qPCR-IA were compared to that obtained using a one-step PicoGreen technology-based commercial kit. The outcome of our study indicates that the development of the novel RT-qPCR-IA will provide rapid and accurate evaluation of the inhibitory efficacy of compounds towards HIV-RT activity. This evaluation could be very useful for large-scale screening of potential new anti-HIV drugs.

Complete inactivation of HIV-1 using photo-labeled non-nucleoside reverse transcriptase inhibitors.

PubMed

Rios, Adan; Quesada, Jorge; Anderson, Dallas; Goldstein, Allan; Fossum, Theresa; Colby-Germinario, Susan; Wainberg, Mark A

2011-01-01

We demonstrate that a photo-labeled derivative of the non-nucleoside reverse transcriptase inhibitor (NNRTI) dapivirine termed DAPY, when used together with exposure to ultraviolet light, was able to completely and irreversibly inactivate both HIV-1 RT activity as well as infectiousness in each of a T cell line and peripheral blood mononuclear cells. Control experiments using various concentrations of DAPY revealed that a combination of exposure to ultraviolet light together with use of the specific, high affinity photo-labeled compound was necessary for complete inactivation to occur. This method of HIV RT inactivation may have applicability toward preservation of an intact viral structure and warrants further investigation in regard to the potential of this approach to elicit a durable, broad protective immune response. Copyright © 2010 Elsevier B.V. All rights reserved.

Etravirine and Rilpivirine Drug Resistance Among HIV-1 Subtype C Infected Children Failing Non-Nucleoside Reverse Transcriptase Inhibitor-Based Regimens in South India.

PubMed

Saravanan, Shanmugam; Kausalya, Bagavathi; Gomathi, Selvamurthi; Sivamalar, Sathasivam; Pachamuthu, Balakrishnan; Selvamuthu, Poongulali; Pradeep, Amrose; Sunil, Solomon; Mothi, Sarvode N; Smith, Davey M; Kantor, Rami

2017-06-01

We have analyzed reverse transcriptase (RT) region of HIV-1 pol gene from 97 HIV-infected children who were identified as failing first-line therapy that included first-generation non-nucleoside RT inhibitors (Nevirapine and Efavirenz) for at least 6 months. We found that 54% and 65% of the children had genotypically predicted resistance to second-generation non-nucleoside RT inhibitors drugs Etravirine (ETR) and Rilpivirine, respectively. These cross-resistance mutations may compromise future NNRTI-based regimens, especially in resource-limited settings. To complement these investigations, we also analyzed the sequences in Stanford database, Monogram weighted score, and DUET weighted score algorithms for ETR susceptibility and found almost perfect agreement between the three algorithms in predicting ETR susceptibility from genotypic data.

Structural optimization of N1-aryl-benzimidazoles for the discovery of new non-nucleoside reverse transcriptase inhibitors active against wild-type and mutant HIV-1 strains.

PubMed

Monforte, Anna Maria; De Luca, Laura; Buemi, Maria Rosa; Agharbaoui, Fatima E; Pannecouque, Christophe; Ferro, Stefania

2018-02-01

Non-nucleoside reverse transcriptase inhibitors (NNRTIs) are recommended components of preferred combination antiretroviral therapies used for the treatment of human immunodeficiency virus (HIV) infection. These regimens are extremely effective in suppressing virus replication. Recently, our research group identified some N 1 -aryl-2-arylthioacetamido-benzimidazoles as a novel class of NNRTIs. In this research work we report the design, the synthesis and the structure-activity relationship studies of new compounds (20-34) in which some structural modifications have been introduced in order to investigate their effects on reverse transcriptase (RT) inhibition and to better define the features needed to increase the antiviral activity. Most of the new compounds proved to be highly effective in inhibiting both RT enzyme at nanomolar concentrations and HIV-1 replication in MT4 cells with minimal cytotoxicity. Among them, the most promising N 1 -aryl-2-arylthioacetamido-benzimidazoles and N 1 -aryl-2-aryloxyacetamido-benzimidazoles were also tested toward a panel of single- and double-mutants strain responsible for resistance to NNRTIs, showing in vitro antiviral activity toward single mutants L100I, K103N, Y181C, Y188L and E138K. The best results were observed for derivatives 29 and 33 active also against the double mutants F227L and V106A. Computational approaches were applied in order to rationalize the potency of the new synthesized inhibitors. Copyright © 2017 Elsevier Ltd. All rights reserved.

Lack of detection of a putative retrovirus associated with haemic neoplasia in the soft shell clam Mya arenaria.

PubMed

AboElkhair, M; Iwamoto, T; Clark, K F; McKenna, P; Siah, A; Greenwood, S J; Berthe, F C J; Casey, J W; Cepica, A

2012-01-01

Haemic neoplasia (HN) is a leukemia-like disease that affects at least 20 species of marine bivalves including soft shell clam, Mya arenaria. Since the disease was discovered in 1969, the etiology remains unknown. A retroviral etiology has been suggested based on the detection of reverse transcriptase activity and electron microscopic observation of retroviral-like particles using negative staining. To date, however no virus isolate and no retroviral sequence from HN has been obtained. Moreover, transmission of the disease by cell-free filtrate from affected clams has not been reproduced. In the current study, we reinvestigated the association of HN with a putative retrovirus. Sucrose gradient centrifugation followed by assessment of reverse transcriptase activity, electrophoretic analysis of protein and RNA, and electron microscopic examinations of fractions corresponding to retroviral density were employed. Detection of retroviral pol sequences using degenerate RT-PCR approaches was also attempted. Our results showed visible bands at the expected density of retrovirus in HN-positive and HN-negative clam tissues and both with reverse transcriptase activity. Electron microscopy, RNA analysis, protein analysis, and PCR systems targeting the pol gene of retroviruses did not however provide clear evidence supporting presence of a retrovirus. We point out that the retrovirus etiology of HN of Mya arenaria proposed some 25 years ago should be reconsidered in the absence of a virus isolate or virus sequences. Copyright © 2011 Elsevier Inc. All rights reserved.

Vascular endothelial growth factor and platelet-derived growth factor are potential angiogenic and metastatic factors in human breast cancer.

PubMed

Anan, K; Morisaki, T; Katano, M; Ikubo, A; Kitsuki, H; Uchiyama, A; Kuroki, S; Tanaka, M; Torisu, M

1996-03-01

Angiogenesis is a prerequisite for tumor growth and metastasis. Tumor angiogenesis may be mediated by several angiogenic factors such as vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), transforming growth factor-alpha, and basic fibroblast growth factor. Differential mRNA expressions of VEGF, PDGF (A chain), transforming growth factor-alpha and basic fibroblast growth factor in 32 primary invasive breast tumors were examined by reverse transcriptase-polymerase chain reaction. We analyzed relationships between mRNA expressions of these angiogenic factors and the degree of angiogenesis, tumor size, and metastasis. Quantification of angiogenesis was achieved by the immunohistochemical staining of endothelial cells with antibody to CD31. VEGF and PDGF-A mRNAs were expressed more frequently in breast tumors than in nontumor breast tissues, whereas no difference was found in expression frequency of either transforming growth factor-alpha or basic fibroblast growth factor mRNA. Vascular counts in tumors correlated with each expression frequency of VEGF and PDGF-A mRNA. PDGF-A mRNA was expressed more frequently in tumors with lymph node metastasis than in those without metastasis. Expression of VEGF and PDGF mRNAs detected by reverse transcriptase-polymerase chain reaction in breast tumors correlates with tumor-related characteristics of angiogenesis and metastatic potential. Analysis of these mRNAs by reverse transcriptase-polymerase chain reaction may be useful for assessing the biologic behavior of a breast tumor before surgical treatment.

Pharmacokinetics of antiretroviral drugs in anatomical sanctuary sites: the male and female genital tract.

PubMed

Else, Laura J; Taylor, Stephen; Back, David J; Khoo, Saye H

2011-01-01

HIV resides within anatomical 'sanctuary sites', where local drug exposure and viral dynamics may differ significantly from the systemic compartment. Suboptimal antiretroviral concentrations in the genital tract may result in compartmentalized viral replication, selection of resistant mutations and possible re-entry of wild-type/resistant virus into the systemic circulation. Therefore, achieving adequate antiretroviral exposure in the genital tract has implications for the prevention of sexual and vertical transmission of HIV. Penetration of antiretrovirals in the genital tract is expressed by accumulation ratios derived from the measurement of drug concentrations in time-matched seminal plasma/cervicovaginal fluid and plasma samples. Penetration varies by gender and may be drug (as opposed to class) specific with high interindividual variability. Concentrations in seminal plasma are highest for nucleoside analogues and lowest for protease inhibitors and efavirenz. Seminal accumulation of newer agents, raltegravir and maraviroc, is moderate (rank order of accumulation is nucleoside/nucleotide reverse transcriptase inhibitors [lamivudine/zidovudine/tenofovir/didanosine > stavudine/abacavir] > raltegravir > indinavir/maraviroc/nevirapine > efavirenz/protease inhibitors [amprenavir/atazanavir/darunavir > lopinavir/ritonavir > saquinavir] > enfuvirtide). In the female genital tract, the nucleoside analogues exhibit high accumulation ratios, whereas protease inhibitors have limited penetration; however, substantial variability exists between individuals and study centres. Second generation non-nucleoside reverse transcriptase inhibitor etravirine, and maraviroc and raltegravir, demonstrate effective accumulation in cervicovaginal secretions (rank order of accumulation is nucleoside/nucleotide reverse transcriptase inhibitor [zidovudine/lamivudine/didanosine > emtricitabine/tenofovir] > indinavir > maraviroc/raltegravir/darunavir/etravirine > nevirapine/abacavir > protease inhibitors [amprenavir/atazanavir/ritonavir] > lopinavir/stavudine/efavirenz > saquinavir).

The baculovirus-integrated retrotransposon TED encodes gag and pol proteins that assemble into viruslike particles with reverse transcriptase.

PubMed Central

Lerch, R A; Friesen, P D

1992-01-01

TED is a lepidopteran retrotransposon found inserted within the DNA genome of the Autographa californica nuclear polyhedrosis virus mutant, FP-D. To examine the proteins and functions encoded by this representative of the gypsy family of retrotransposons, the gag- and pol-like open reading frames (ORFs 1 and 2) were expressed in homologous lepidopteran cells by using recombinant baculovirus vectors. Expression of ORF 1 resulted in synthesis of an abundant TED-specific protein (Pr55gag) that assembled into viruslike particles with a diameter of 55 to 60 nm. Expression of ORF 2, requiring a -1 translational frameshift, resulted in synthesis of a protease that mediated cleavage of Pr55gag to generate p37, the major protein component of the resulting particles. Expression of ORF 2 also produced reverse transcriptase that associated with these particles. Both protease and reverse transcriptase activities mapped to domains within ORF 2 that contain sequence similarities with the corresponding functional domains of the pol gene of the vertebrate retroviruses. These results indicated that TED ORFs 1 and 2 functionally resemble the retrovirus gag and pol genes and demonstrated for the first time that an invertebrate member of the gypsy family of elements encodes active forms of the structural and enzymatic functions necessary for transposition via an RNA intermediate. TED integration within the baculovirus genome thus represents one of the first examples of transposon-mediated transfer of host-derived genes to an eukaryotic virus. Images PMID:1371168

HIV drug resistance in infants increases with changing prevention of mother-to-child transmission regimens.

PubMed

Poppe, Lisa K; Chunda-Liyoka, Catherine; Kwon, Eun H; Gondwe, Clement; West, John T; Kankasa, Chipepo; Ndongmo, Clement B; Wood, Charles

2017-08-24

The objectives of this study were to determine HIV drug resistance (HIVDR) prevalence in Zambian infants upon diagnosis, and to determine how changing prevention of mother-to-child transmission (PMTCT) drug regimens affect drug resistance. Dried blood spot (DBS) samples from infants in the Lusaka District of Zambia, obtained during routine diagnostic screening, were collected during four different years representing three different PMTCT drug treatment regimens. DNA extracted from dried blood spot samples was used to sequence a 1493 bp region of the reverse transcriptase gene. Sequences were analyzed via the Stanford HIVDRdatabase (http://hivdb.standford.edu) to screen for resistance mutations. HIVDR in infants increased from 21.5 in 2007/2009 to 40.2% in 2014. Nonnucleoside reverse transcriptase inhibitor resistance increased steadily over the sampling period, whereas nucleoside reverse transcriptase inhibitor resistance and dual class resistance both increased more than threefold in 2014. Analysis of drug resistance scores in each group revealed increasing strength of resistance over time. In 2014, children with reported PMTCT exposure, defined as infant prophylaxis and/or maternal treatment, showed a higher prevalence and strength of resistance compared to those with no reported exposure. HIVDR is on the rise in Zambia and presents a serious problem for the successful lifelong treatment of HIV-infected children. PMTCT affects both the prevalence and strength of resistance and further research is needed to determine how to mitigate its role leading to resistance.

In Vitro Resistance Profile of the Candidate HIV-1 Microbicide Drug Dapivirine

PubMed Central

Schader, Susan M.; Oliveira, Maureen; Ibanescu, Ruxandra-Ilinca; Moisi, Daniela; Colby-Germinario, Susan P.

2012-01-01

Antiretroviral-based microbicides may offer a means to reduce the sexual transmission of HIV-1. Suboptimal use of a microbicide may, however, lead to the development of drug resistance in users that are already, or become, infected with HIV-1. In such cases, the efficacy of treatments may be compromised since the same (or similar) antiretrovirals used in treatments are being developed as microbicides. To help predict which drug resistance mutations may develop in the context of suboptimal use, HIV-1 primary isolates of different subtypes and different baseline resistance profiles were used to infect primary cells in vitro in the presence of increasing suboptimal concentrations of the two candidate microbicide antiretrovirals dapivirine (DAP) and tenofovir (TFV) alone or in combination. Infections were ongoing for 25 weeks, after which reverse transcriptase genotypes were determined and scrutinized for the presence of any clinically recognized reverse transcriptase drug resistance mutations. Results indicated that suboptimal concentrations of DAP alone facilitated the emergence of common nonnucleoside reverse transcriptase inhibitor resistance mutations, while suboptimal concentrations of DAP plus TFV gave rise to fewer mutations. Suboptimal concentrations of TFV alone did not frequently result in the development of resistance mutations. Sensitivity evaluations for stavudine (d4T), nevirapine (NVP), and lamivudine (3TC) revealed that the selection of resistance as a consequence of suboptimal concentrations of DAP may compromise the potential for NVP to be used in treatment, a finding of potential relevance in developing countries. PMID:22123692

In vitro resistance profile of the candidate HIV-1 microbicide drug dapivirine.

PubMed

Schader, Susan M; Oliveira, Maureen; Ibanescu, Ruxandra-Ilinca; Moisi, Daniela; Colby-Germinario, Susan P; Wainberg, Mark A

2012-02-01

Antiretroviral-based microbicides may offer a means to reduce the sexual transmission of HIV-1. Suboptimal use of a microbicide may, however, lead to the development of drug resistance in users that are already, or become, infected with HIV-1. In such cases, the efficacy of treatments may be compromised since the same (or similar) antiretrovirals used in treatments are being developed as microbicides. To help predict which drug resistance mutations may develop in the context of suboptimal use, HIV-1 primary isolates of different subtypes and different baseline resistance profiles were used to infect primary cells in vitro in the presence of increasing suboptimal concentrations of the two candidate microbicide antiretrovirals dapivirine (DAP) and tenofovir (TFV) alone or in combination. Infections were ongoing for 25 weeks, after which reverse transcriptase genotypes were determined and scrutinized for the presence of any clinically recognized reverse transcriptase drug resistance mutations. Results indicated that suboptimal concentrations of DAP alone facilitated the emergence of common nonnucleoside reverse transcriptase inhibitor resistance mutations, while suboptimal concentrations of DAP plus TFV gave rise to fewer mutations. Suboptimal concentrations of TFV alone did not frequently result in the development of resistance mutations. Sensitivity evaluations for stavudine (d4T), nevirapine (NVP), and lamivudine (3TC) revealed that the selection of resistance as a consequence of suboptimal concentrations of DAP may compromise the potential for NVP to be used in treatment, a finding of potential relevance in developing countries.

Evaluation of different embryonating bird eggs and cell cultures for isolation efficiency of avian influenza A virus and avian paramyxovirus serotype 1 from real-time reverse transcription polymerase chain reaction--positive

USDA-ARS?s Scientific Manuscript database

Two hundred samples collected from Anseriformes, Charadriiformes, Gruiformes, and Galliformes were assayed using real-time reverse transcriptase polymerase chain reaction (RRT-PCR) for presence of avian influenza virus and avian paramyxovirus-1. Virus isolation using embryonating chicken eggs, embr...

Strand-specific real-time RT-PCR quantitation of Maize fine streak virus genomic and positive-sense RNAs using high temperature reverse transcription

USDA-ARS?s Scientific Manuscript database

Efforts to analyze the replicative RNA produced by Maize fine streak virus (MVSF) within maize tissue was complicated by the lack of specificity during cDNA generation using standard reverse transcriptase protocols. Real-time qRT-PCR using cDNA generated by priming with random hexamers does not dist...

Reverse transcription of phage RNA and its fragment directed by synthetic heteropolymeric primers

PubMed Central

Frolova, L. Yu.; Metelyev, V. G.; Ratmanova, K. I.; Smirnov, V. D.; Shabarova, Z. A.; Prokofyev, M. A.; Berzin, V. M.; Jansone, I. V.; Gren, E. J.; Kisselev, L. L.

1977-01-01

DNA synthesis catalysed by RNA-directed DNA-polymerase (reverse transcriptase) was found to proceed on the RNA template of an MS2 phage in the presence of heteropolymeric synthetic octa- and nonadeoxyribonucleotide primers complementary to the intercistronic region (coat protein binding site) and the region of the coat protein cistron, respectively. The product of synthesis consists of discrete DNA fractions of different length, including transcripts longer than 1,000 nucleotides. The coat protein inhibits DNA synthesis if it is initiated at its binding site, but has no effect on DNA synthesis initiated at the coat protein cistron. It has been suggested that, in this system, the initiation of DNA synthesis by synthetic primers is topographically specific. The MS2 coat protein binding site (an RNA fragment of 59 nucleotides) serves as a template for polydeoxyribonucleotide synthesis in the presence of octanucleotide primer and reverse transcriptase. The product of synthesis is homogenous and its length corresponds to the length of the template. The effective and complete copying of the fragment having a distinct secondary structure proves that the secondary structure does not interfere, in principle, with RNA being a template in the system of reverse transcription. PMID:71713

Novel method to assess antiretroviral target trough concentrations using in vitro susceptibility data.

PubMed

Acosta, Edward P; Limoli, Kay L; Trinh, Lan; Parkin, Neil T; King, Jennifer R; Weidler, Jodi M; Ofotokun, Ighovwerha; Petropoulos, Christos J

2012-11-01

Durable suppression of HIV-1 replication requires the establishment of antiretroviral drug concentrations that exceed the susceptibility of the virus strain(s) infecting the patient. Minimum plasma drug concentrations (C(trough)) are correlated with response, but determination of target C(trough) values is hindered by a paucity of in vivo concentration-response data. In the absence of these data, in vitro susceptibility measurements, adjusted for serum protein binding, can provide estimations of suppressive in vivo drug concentrations. We derived serum protein binding correction factors (PBCF) for protease inhibitors, nonnucleoside reverse transcriptase inhibitors, and an integrase inhibitor by measuring the effect of a range of human serum concentrations on in vitro drug susceptibility measured with the PhenoSense HIV assay. PBCFs corresponding to 100% HS were extrapolated using linear regression and ranged from 1.4 for nevirapine to 77 for nelfinavir. Using the mean 95% inhibitory concentration (IC(95)) for ≥1,200 drug-susceptible viruses, we calculated protein-bound IC(95) (PBIC(95)) values. PBIC(95) values were concordant with the minimum effective C(trough) values that were established in well-designed pharmacodynamic studies (e.g., indinavir, saquinavir, and amprenavir). In other cases, the PBIC(95) values were notably lower (e.g., darunavir, efavirenz, and nevirapine) or higher (nelfinavir and etravirine) than existing target recommendations. The establishment of PBIC(95) values as described here provides a convenient and standardized approach for estimation of the minimum drug exposure that is required to maintain viral suppression and prevent the emergence of drug-resistant variants, particularly when in vivo concentration-response relationships are lacking.

Novel Method To Assess Antiretroviral Target Trough Concentrations Using In Vitro Susceptibility Data

PubMed Central

Limoli, Kay L.; Trinh, Lan; Parkin, Neil T.; King, Jennifer R.; Weidler, Jodi M.; Ofotokun, Ighovwerha; Petropoulos, Christos J.

2012-01-01

Durable suppression of HIV-1 replication requires the establishment of antiretroviral drug concentrations that exceed the susceptibility of the virus strain(s) infecting the patient. Minimum plasma drug concentrations (Ctrough) are correlated with response, but determination of target Ctrough values is hindered by a paucity of in vivo concentration-response data. In the absence of these data, in vitro susceptibility measurements, adjusted for serum protein binding, can provide estimations of suppressive in vivo drug concentrations. We derived serum protein binding correction factors (PBCF) for protease inhibitors, nonnucleoside reverse transcriptase inhibitors, and an integrase inhibitor by measuring the effect of a range of human serum concentrations on in vitro drug susceptibility measured with the PhenoSense HIV assay. PBCFs corresponding to 100% HS were extrapolated using linear regression and ranged from 1.4 for nevirapine to 77 for nelfinavir. Using the mean 95% inhibitory concentration (IC95) for ≥1,200 drug-susceptible viruses, we calculated protein-bound IC95 (PBIC95) values. PBIC95 values were concordant with the minimum effective Ctrough values that were established in well-designed pharmacodynamic studies (e.g., indinavir, saquinavir, and amprenavir). In other cases, the PBIC95 values were notably lower (e.g., darunavir, efavirenz, and nevirapine) or higher (nelfinavir and etravirine) than existing target recommendations. The establishment of PBIC95 values as described here provides a convenient and standardized approach for estimation of the minimum drug exposure that is required to maintain viral suppression and prevent the emergence of drug-resistant variants, particularly when in vivo concentration-response relationships are lacking. PMID:22964257

ICECAP: an integrated, general-purpose, automation-assisted IC50/EC50 assay platform.

PubMed

Li, Ming; Chou, Judy; King, Kristopher W; Jing, Jing; Wei, Dong; Yang, Liyu

2015-02-01

IC50 and EC50 values are commonly used to evaluate drug potency. Mass spectrometry (MS)-centric bioanalytical and biomarker labs are now conducting IC50/EC50 assays, which, if done manually, are tedious and error-prone. Existing bioanalytical sample preparation automation systems cannot meet IC50/EC50 assay throughput demand. A general-purpose, automation-assisted IC50/EC50 assay platform was developed to automate the calculations of spiking solutions and the matrix solutions preparation scheme, the actual spiking and matrix solutions preparations, as well as the flexible sample extraction procedures after incubation. In addition, the platform also automates the data extraction, nonlinear regression curve fitting, computation of IC50/EC50 values, graphing, and reporting. The automation-assisted IC50/EC50 assay platform can process the whole class of assays of varying assay conditions. In each run, the system can handle up to 32 compounds and up to 10 concentration levels per compound, and it greatly improves IC50/EC50 assay experimental productivity and data processing efficiency. © 2014 Society for Laboratory Automation and Screening.

A deletion mutation in the 5' part of the pol gene of Moloney murine leukemia virus blocks proteolytic processing of the gag and pol polyproteins.

PubMed Central

Crawford, S; Goff, S P

1985-01-01

Deletion mutations in the 5' part of the pol gene of Moloney murine leukemia virus were generated by restriction enzyme site-directed mutagenesis of cloned proviral DNA. DNA sequence analysis indicated that one such deletion was localized entirely within the 5' part of the pol gene, did not affect the region encoding reverse transcriptase, and preserved the translational reading frame downstream of the mutation. The major viral precursor polyproteins (Pr65gag, Pr200gag-pol, and gPr80env) were synthesized at wild-type levels in cell lines carrying the mutant genome. These cell lines assembled and released wild-type levels of virion particles into the medium. Cleavage of both Pr65gag and Pr200gag-pol precursors to the mature proteins was completely blocked in the mutant virions. Surprisingly, these virions contained high levels of active reverse transcriptase; examination of the endogenous reverse transcription products synthesized by the mutant virions revealed normal amounts of minus-strand strong-stop DNA, indicating that the RNA genome was packaged and that reverse transcription in detergent-permeabilized virions was not significantly impaired. Processing of gPr80env to gP70env and P15E was not affected by the mutation, but cleavage of P15E to P12E was not observed. The mutant particles were poorly infectious; analysis indicated that infection was blocked at an early stage. The data are consistent with the idea that the 5' part of the pol gene encodes a protease directly responsible for processing Pr65gag, and possibly Pr200gag-pol, to the structural virion proteins. It appears that cleavage of the gag gene product is not required for budding and release of virions and that complete processing of the pol gene product to the mature form of reverse transcriptase is not required for its functional activation. Images PMID:3882995

Cloning, expression and functional role of a nociceptin/orphanin FQ receptor in the porcine gastrointestinal tract.

PubMed

Osinski, M A; Pampusch, M S; Murtaugh, M P; Brown, D R

1999-01-22

The heptadecapeptide nociceptin/orphanin FQ is the cognate ligand for the opioid receptor-like orphanin FQ (OFQ) receptor, a member of the G protein-coupled receptor superfamily. The gastrointestinal tract is a major site of opioid action, and preliminary evidence suggests that an OFQ receptor may be expressed in rat small intestine. We addressed the hypothesis that this receptor is expressed in the gastrointestinal tract of the pig, a model for the human digestive system. A 1205-bp cDNA was isolated from porcine forebrain which contained the 370 amino acid open reading frame encoding the OFQ receptor. The receptor mRNA is likely to arise from a single gene, as determined by Southern blotting of porcine genomic DNA restriction digests using a porcine OFQ receptor cDNA probe. A semi-nested reverse transcriptase-polymerase chain reaction survey of receptor mRNA indicates that it is expressed in the porcine cerebral cortex and kidney, and along the length of the gastrointestinal tract. OFQ decreased initial contractile responses of porcine ileal smooth muscle strips to trains of electrical field stimulation with an IC50 value of 1.3 nM; its effects were resistant to the opioid antagonist, naloxone. The peptide, at concentrations > or =3 nM, also attenuated Isc elevations evoked by electrical transmural stimulation of mucosa-submucosa sheets from porcine ileum. The actions of OFQ appeared to differ from those previously reported for opioid receptor agonists in these tissue preparations. These results indicate that an OFQ receptor is expressed in the porcine intestine which modulates the neural control of intestinal smooth muscle contractility and mucosal transport.

In vitro assessment of competitive and time-dependent inhibition of the nevirapine metabolism by nortriptyline in rats.

PubMed

Usach, Iris; Ferrer, José-Maria; Peris, José-Esteban

2018-04-17

Nevirapine (NVP) is a non-nucleoside reverse transcriptase inhibitor of human immunodeficiency virus type 1 (HIV-1) widely used as a component of High Active Antiretroviral Therapy (HAART) since it is inexpensive, readily absorbed after oral administration and non-teratogenic. In the present work, the mechanism of a previously described pharmacokinetic interaction between NVP and the antidepressant drug nortriptyline (NT) was studied using rat hepatic microsomes. The obtained results showed a competitive inhibition of the NVP metabolism by NT. The three main NVP metabolites (2-OH-NVP, 3-OH-NVP and 12-OH-NVP) where competitively inhibited with similar inhibitory constant values (K i  = 4.01, 3.97 and 4.40 μM, respectively). Time-dependent inhibition of the NVP metabolism was also detected, with a 2.5-fold reduction in the IC 50 values of NT for 2-, 3-, and 12-OH-NVP formation when NT was preincubated with the microsomal suspension in the presence of an NADPH-generating system. A concentration-dependent inhibition of the formation of NVP metabolites by the main NT metabolite (10-OH-NT) was also observed, however, the inhibitory potency of 10-OH-NT was much lower than that of the parent drug. The apparent hepatic intrinsic clearance of NVP determined in these in vitro experiments was used to predict the in vivo clearance of NVP using the "well-stirred" and the "parallel-tube" models, resulting in values close to those previously observed in vivo clearance. Finally, a good prediction of the increase in the plasma concentrations of NVP when co-administered with NT was obtained employing the inhibitory constant of NT determined in vitro and the estimated plasma concentration of NT entering the liver. Copyright © 2018. Published by Elsevier Inc.

Use of alternative alkali chlorides in RT and PCR of polynucleotides containing G quadruplex structures.

PubMed

Ramos-Alemán, Fabiola; González-Jasso, Eva; Pless, Reynaldo C

2018-02-15

Several alkali chlorides were compared for their use in reverse transcription (RT) and PCR of different types of nucleic acid templates. On a test region of biological DNA incapable of forming G quadruplex (G4) structures, Taq DNA polymerase showed similar PCR performance with 50 mM KCl, CsCl, LiCl, and NaCl. In contrast, on a synthetic model polydeoxyribonucleotide prone to G4 formation, good PCR amplification was obtained with 50 mM CsCl, but little or none with LiCl or KCl. Similarly, in RT of a G4-prone model polyribonucleotide, MMLV reverse transcriptase produced a good yield with 50 mM CsCl, mediocre yields with LiCl or without added alkali chloride, and a poor yield with 50 mM KCl. The full RT-PCR assay starting from the G4-prone polyribonucleotide, showed good results with CsCl in both stages, poor results with LiCl, and no product formation with KCl. The model polynucleotides showed fast G quadruplex formation under PCR or RT conditions with 50 mM KCl, but not with CsCl or LiCl. The results argue for the use of CsCl instead of KCl for RT and PCR of G4-prone sequences. No advantage was observed when using the 7-deaza type nucleotide analog c 7 dGTP in PCR amplification of the G4-prone polydeoxyribonucleotide. Copyright © 2017 Elsevier Inc. All rights reserved.

Genotypic tropism testing of proviral DNA to guide maraviroc initiation in aviraemic subjects: 48-week analysis of results from the PROTEST study.

PubMed

Poveda, E; Hernández-Quero, J; Pérez-Elías, M J; Ribas, M A; Martínez-Madrid, O J; Flores, J; Navarro, J; Gutiérrez, F; García-Deltoro, M; Imaz, A; Ocampo, A; Artero, A; Blanco, F; Bernal, E; Pasquau, J; Mínguez-Gallego, C; Pérez, N; Aiestaran, A; García, F; Paredes, R

2017-08-01

Maraviroc (MVC) is a suitable drug for aviraemic subjects on antiretroviral treatment (ART) developing toxicity. Its prescription requires prior tropism testing. It is unknown if proviral DNA genotypic tropism testing is reliable for guiding MVC initiation in aviraemic subjects, so this study was carried out to address this issue. PROTEST was a phase 4, prospective, single-arm clinical trial carried out in 24 HIV care centres in Spain. MVC-naïve HIV-1-infected patients with HIV-1 RNA < 50 copies/mL on stable ART during the previous 6 months who required an ART change because of toxicity and who had R5 HIV, as determined by proviral DNA genotypic tropism testing, initiated MVC with two nucleoside reverse transcriptase inhibitors (NRTIs) and were followed for 48 weeks. Virological failure was defined as two consecutive viral load measurements > 50 copies/mL. Tropism results were available for 141 of 175 (80.6%) subjects screened: 60% had R5 and 85% of these (n = 74) were finally included in the study. Previous ART included protease inhibitors (PIs) in 62% of subjects, nonnucleoside reverse transcriptase inhibitors (NNRTIs) in 36%, and integrase inhibitors (INIs) in 2%. Main reasons for treatment change were dyslipidaemia (42%), gastrointestinal symptoms (22%) and liver toxicity (15%). MVC was given alongside tenofovir (TDF)/emtricitabine (FTC) (54%) and abacavir (ABC)/lamivudine (3TC) (40%) in most patients. Eighty-four per cent of patients maintained a viral load < 50 copies/mL to week 48, whereas 16% discontinued treatment: two withdrew informed consent, one had an R5 to X4 shift between screening and baseline, one was lost to follow-up, one developed an adverse event (rash), two died from non-study-related causes, and five developed protocol-defined virological failure. Initiation of MVC plus two NRTIs in aviraemic subjects based on genotypic tropism testing of proviral HIV-1 DNA is associated with low rates of virological failure for up to 1 year. © 2016 British HIV Association.

Short communication: a repeated simian human immunodeficiency virus reverse transcriptase/herpes simplex virus type 2 cochallenge macaque model for the evaluation of microbicides.

PubMed

Kenney, Jessica; Derby, Nina; Aravantinou, Meropi; Kleinbeck, Kyle; Frank, Ines; Gettie, Agegnehu; Grasperge, Brooke; Blanchard, James; Piatak, Michael; Lifson, Jeffrey D; Zydowsky, Thomas M; Robbiani, Melissa

2014-11-01

Epidemiological studies suggest that prevalent herpes simplex virus type 2 (HSV-2) infection increases the risk of HIV acquisition, underscoring the need to develop coinfection models to evaluate promising prevention strategies. We previously established a single high-dose vaginal coinfection model of simian human immunodeficiency virus (SHIV)/HSV-2 in Depo-Provera (DP)-treated macaques. However, this model does not appropriately mimic women's exposure. Repeated limiting dose SHIV challenge models are now used routinely to test prevention strategies, yet, at present, there are no reports of a repeated limiting dose cochallenge model in which to evaluate products targeting HIV and HSV-2. Herein, we show that 20 weekly cochallenges with 2-50 TCID50 simian human immunodeficiency virus reverse transcriptase (SHIV-RT) and 10(7) pfu HSV-2 results in infection with both viruses (4/6 SHIV-RT, 6/6 HSV-2). The frequency and level of vaginal HSV-2 shedding were significantly greater in the repeated exposure model compared to the single high-dose model (p<0.0001). We used this new model to test the Council's on-demand microbicide gel, MZC, which is active against SHIV-RT in DP-treated macaques and HSV-2 and human papillomavirus (HPV) in mice. While MZC reduced SHIV and HSV-2 infections in our repeated limiting dose model when cochallenging 8 h after each gel application, a barrier effect of carrageenan (CG) that was not seen in DP-treated animals precluded evaluation of the significance of the antiviral activity of MZC. Both MZC and CG significantly (p<0.0001) reduced the frequency and level of vaginal HSV-2 shedding compared to no gel treatment. This validates the use of this repeated limiting dose cochallenge model for testing products targeting HIV and HSV-2.

Investigating the Effect of Emetic Compounds on Chemotaxis in Dictyostelium Identifies a Non-Sentient Model for Bitter and Hot Tastant Research

PubMed Central

Robery, Steven; Mukanowa, Janina; Percie du Sert, Nathalie; Andrews, Paul L. R.; Williams, Robin S. B.

2011-01-01

Novel chemical entities (NCEs) may be investigated for emetic liability in a range of unpleasant experiments involving retching, vomiting or conditioned taste aversion/food avoidance in sentient animals. We have used a range of compounds with known emetic /aversive properties to examine the possibility of using the social amoeba, Dictyostelium discoideum, for research into identifying and understanding emetic liability, and hence reduce adverse animal experimentation in this area. Twenty eight emetic or taste aversive compounds were employed to investigate the acute (10 min) effect of compounds on Dictyostelium cell behaviour (shape, speed and direction of movement) in a shallow chemotaxic gradient (Dunn chamber). Compound concentrations were chosen based on those previously reported to be emetic or aversive in in vivo studies and results were recorded and quantified by automated image analysis. Dictyostelium cell motility was rapidly and strongly inhibited by four structurally distinct tastants (three bitter tasting compounds - denatonium benzoate, quinine hydrochloride, phenylthiourea, and the pungent constituent of chilli peppers - capsaicin). In addition, stomach irritants (copper chloride and copper sulphate), and a phosphodiesterase IV inhibitor also rapidly blocked movement. A concentration-dependant relationship was established for five of these compounds, showing potency of inhibition as capsaicin (IC50 = 11.9±4.0 µM) > quinine hydrochloride (IC50 = 44.3±6.8 µM) > denatonium benzoate (IC50 = 129±4 µM) > phenylthiourea (IC50 = 366±5 µM) > copper sulphate (IC50 = 1433±3 µM). In contrast, 21 compounds within the cytotoxic and receptor agonist/antagonist classes did not affect cell behaviour. Further analysis of bitter and pungent compounds showed that the effect on cell behaviour was reversible and not cytotoxic, suggesting an uncharacterised molecular mechanism of action for these compounds. These results therefore demonstrate that Dictyostelium has potential as a non-sentient model in the analysis of the molecular effects of tastants, although it has limited utility in identification of emetic agents in general. PMID:21931717

Bacterial Group II Introns: Identification and Mobility Assay.

PubMed

Toro, Nicolás; Molina-Sánchez, María Dolores; Nisa-Martínez, Rafael; Martínez-Abarca, Francisco; García-Rodríguez, Fernando Manuel

2016-01-01

Group II introns are large catalytic RNAs and mobile retroelements that encode a reverse transcriptase. Here, we provide methods for their identification in bacterial genomes and further analysis of their splicing and mobility capacities.

Anti-human immunodeficiency virus (HIV) activities of halogenated gomisin J derivatives, new nonnucleoside inhibitors of HIV type 1 reverse transcriptase.

PubMed

Fujihashi, T; Hara, H; Sakata, T; Mori, K; Higuchi, H; Tanaka, A; Kaji, H; Kaji, A

1995-09-01

Halogenated gomisin J (a derivative of lignan compound), represented by the bromine derivative 1506 [(6R, 7S, S-biar)-4,9-dibromo-3,10-dihydroxy-1,2,11,12-tetramethoxy-6, 7-dimethyl-5,6,7,8- tetrahydrodibenzo[a,c]cyclo-octene], was found to be a potent inhibitor of the cytopathic effects of human immunodeficiency virus type 1 (HIV-1) on MT-4 human T cells (50% effective dose, 0.1 to 0.5 microM). Gomisin J derivatives were active in preventing p24 production from acutely HIV-1-infected H9 cells. The selective indices (toxic dose/effective dose) of these compounds were as high as > 300 in some systems. 1506 was active against 3'-azido-3'-deoxythymidine-resistant HIV-1 and acted synergistically with AZT and 2',3'-ddC. 1506 inhibited HIV-1 reverse transcriptase (RT) in vitro but not HIV-1 protease. From the time-of-addition experiment, 1506 was found to inhibit the early phase of the HIV life cycle. A 1506-resistant HIV mutant was selected and shown to possess a mutation within the RT-coding region (at position 188 [Tyr to Leu]). The mutant RT expressed in Escherichia coli was resistant to 1506 in the in vitro RT assay. Some of the HIV strains resistant to other nonnucleoside HIV-1 RT inhibitors were also resistant to 1506. Comparison of various gomisin J derivatives with gomisin J showed that iodine, bromine, and chlorine in the fourth and ninth positions increased RT inhibitory activity as well as cytoprotective activity.

Telomerase activity-independent function of telomerase reverse transcriptase is involved in acrylamide-induced neuron damage.

PubMed

Zhang, P; Pan, H; Wang, J; Liu, X; Hu, X

2014-07-01

Polyacrylamide is used widely in industry, and its decomposition product, acrylamide (ACR), readily finds its way into commonly consumed cosmetics and baked and fried foods. ACR exerts potent neurotoxic effects in human and animal models. Telomerase reverse transcriptase (TERT), the catalytic subunit of telomerase, traditionally has been considered to play an important role in maintaining telomere length. Emerging evidence has shown, however, that TERT plays an important role in neuroprotection by inhibiting apoptosis and excitotoxicity, and by promoting angiogenesis, neuronal survival and neurogenesis, which are closely related to the telomere-independent functions of TERT. We investigated whether and how the TERT pathway is involved in ACR induced neurotoxicity in rat cortical neurons. We found that ACR 1) significantly reduced the viability of cortical neurons as measured by MTT assay, 2) induced neuron apoptosis as revealed by FITC-conjugated Annexin V/PI double staining and flow cytometry (FACS) analysis, 3) elevated expression of cleaved caspase-3, and 4) decreased bcl-2 expression of cortical neurons. ACR also increased intracellular ROS levels in cortical neurons, increased MDA levels and reduced GSH, SOD and GSH-Px levels in mitochondria in a dose-dependent manner. We found that TERT expression in mitochondria was increased by ACR at concentrations of 2.5 and 5.0 mM, but TERT expression was decreased by 10 mM ACR. Telomerase activity, however, was undetectable in rat cortical neurons. Our results suggest that the TERT pathway is involved in ACR induced apoptosis of cortical neurons. TERT also may exert its neuroprotective role in a telomerase activity-independent way, especially in mitochondria.

[Triptolide reverses apatinib resistance in gastric cancer cell line MKN45 via inhibition of heat shock protein 70].

PubMed

Teng, F; Xu, Z Y; Lyu, H; Wang, Y P; Wang, L J; Huang, T; Sun, J C; Zhu, H T; Ni, Y X; Cheng, X D

2018-02-23

Objective: To investigate the effect of triptolide, a specific inhibitor of heat shock protein 70 (HSP70), on apatinib resistance in gastric cancer cells line MKN45. Methods: The apatinib-resistant cells (MKN45/AR) and MKN45 parental cells were treated with apatinib, triptolide and apatinib combined with triptolide, respectively. CCK-8 assay was performed to determine the half maximal inhibitory concentration (IC(50)) of MKN45/AR and MKN45 cells in the presence of different treatment. The mRNA expression of heat shock protein gene (HSPA1A and HSPA1B) was detected by RT-PCR, while the protein expression of heat shock protein 70 was analyzed using Western blot in MKN45/AR and MKN45 cells. Results: The IC(50) values of apatinib-sensitive and apatinib-resistant MKN45 cells were 10.411 μmol/L and 70.527 μmol/L, respectively, showing a significant difference ( P <0.05). The mRNA expression of HSPA1A and HSPA1B in MKN45/AR cells was significantly higher than that in MKN45 cells ( P <0.001). The protein expression of heat shock protein 70 was significantly decreased after 0.25 μmol/L triptolide treatment in MKN45/AR cells ( P <0.01). When heat shock protein 70 was inhibited by triptolide, the IC(50) value of apatinib in MKN45/AR cells was reduced to 11.679 μmol/L, which was significantly lower than cells treated with apatinib alone ( P <0.05). Conclusions: The apatinib-resistant MKN45 cells have high levels of heat shock protein 70. Low doses of triptolide can significantly inhibit heat shock protein 70, leading to reverse the resistance phenotype of MKN45/AR cells. Therefore, inhibition of heat shock protein 70 provides a new therapy strategy for patients with apatinib resistance.

MD-1, a poly herbal formulation indicated in diabetes mellitus ameliorates glucose uptake and inhibits adipogenesis - an in vitro study.

PubMed

Telapolu, Srivani; Kalachavedu, Mangathayaru; Punnoose, Alan Mathew; Bilikere, Dwarakanath

2018-04-02

Type 2 Diabetes (T2D) is a polygenic disease requiring a multipronged therapeutic approach. In the current scenario, the use of polyherbals is increasing among the diabetics. MD-1, a poly herbal formulation is constituted as a mixture of six popular anti diabetic herbs, used in the management of Diabetes mellitus (DM). The physicochemical, biochemical and in vitro efficacy studies have been carried out to ascertain the possible mechanisms underlying the anti-diabetic action of MD-1. MD-1 was evaluated for residual toxins as per Ayurvedic Pharmacoepia of India (API) procedures. The hydro alcoholic extract of the formulation (HAEF) was evaluated for anti oxidant activity against 2, 2-diphenyl-1-picrylhydrazil (DPPH) and nitric oxide radicals in vitro. The effect of HAEF on carbohydrate digestive enzymes α-glucosidase and α-amylase was studied using biochemical assays. HAEF was studied for its glucose lowering potential in L6 myotubes and 3T3L1 preadipocytes, using 2-deoxy-D-[1- 3 H] glucose (2-DG) uptake assay. Effect of MD-1 on adipogenesis was evaluated in 3T3L1 adipocytes using oil O red staining. The effect of HAEF on mRNA expression of peroxisome proliferator activated receptor gamma (PPARγ) and glucose transporter 4 (GLUT4) in 3T3L1 adiocytes was investigated by reverse transcriptase polymerase chain reaction (RT-PCR). Statistical analysis was performed by student t-test, ANOVA. Residual toxins present within the API limits and HAEF demonstrated strong antioxidant potential and significantly inhibited the α-glucosidase (IC 50 63.6 ± 0.46 μg/mL) and α-amylase (IC 50 242.81 ± 1.26 μg/mL) activity. HAEF significantly (p < 0.05) enhanced the insulin stimulated glucose uptake in both the cell lines studied. Unlike standard pioglitazone (PGZ), HAEF modulated the mRNA expression of PPARγ and GLUT4 (p < 0.0001) in 3T3L1 adipocytes, without inducing adipogenesis. Physicochemical parameters established in the study may serve as reference standards in regular quality control. Absence of residual toxins underpins the safety. The enhanced glucose uptake and favorable modulation of insulin sensitivity through a plausible weak PPARγ agonism is similar to the distinct PPARγ activation pattern of several reported natural compound agonists. The differential binding modes of such dynamic combinatorial ligands within the formulation unlike synthetic ligands like thiozolidinediones (TZD) can be linked to the safe mitigation of diabetic complications by MD-1.

[Effects of cornel iridoid glycoside on activity of cholinesterases in vitro].

PubMed

Chu, Si-Juan; Zhang, Lan; Liu, Gang; Zhou, Wen-Xia; Li, Lin

2013-05-01

The purpose of the present study was to investigate the effects of cornel iridoid glycoside (CIG) on the activity of cholinesterases in vitro, and to investigate the mechanism of CIG's treating Alzheimer's disease (AD). The sources of cholinesterases were prepared from human blood cells, rat brain homogenate and human blood plasma, respectively. The biochemical methods were used to detect the activity of acetylcholine esterase (AChE) and butyryl cholinesterase (BuChE) to investigate the influence of CIG on cholinesterases. The results showed that CIG inhibited the activity of AChE of human blood cells and rat brain homogenate, with the 50% inhibition rate (IC50) of 1.6 g . L-1 and 3.3 g . L-1, respectively; and the inhibition of AChE of CIG is reversible. CIG also inhibited the activity of BuChE of human blood plasma, with the IC50 of 2.9 g . L-1. In conclusion, CIG can inhibit the activity of AChE and BuChE in vitro, which may be one of the mechanisms of CIG to treat AD.

Cytotoxic activity of quassinoids from Eurycoma longifolia.

PubMed

Miyake, Katsunori; Li, Feng; Tezuka, Yasuhiro; Awale, Suresh; Kadota, Shigetoshi

2010-07-01

Twenty-four quassinoids isolated from Eurycoma longifolia Jack were investigated for their cytotoxicity against a panel of four different cancer cell lines, which includes three murine cell lines [colon 26-L5 carcinoma (colon 26-L5), B16-BL6 melanoma (B16-BL6), Lewis lung carcinoma (LLC)] and a human lung A549 adenocarcinoma (A549) cell line. Among the tested compounds, eurycomalactone (9) displayed the most potent activity against all the tested cell lines; colon 26-L5 (IC50 = 0.70 microM), B16-BL6 (IC50 = 0.59 microM), LLC (IC50 = 0.78 microM), and A549 (IC50 = 0.73 microM). These activities were comparable to clinically used anticancer agent doxorubicin (colon 26-L5, IC50 = 0.76 microM; B16-BL6, IC50 = 0.86 microM; LLC, IC50 = 0.80 microM; A549, IC50 = 0.66 microM).

Development of a multiplex probe combination-based one-step real-time reverse transcription-PCR for NA subtype typing of avian influenza virus.

PubMed

Sun, Zhihao; Qin, Tao; Meng, Feifei; Chen, Sujuan; Peng, Daxin; Liu, Xiufan

2017-10-18

Nine influenza virus neuraminidase (NA) subtypes have been identified in poultry and wild birds. Few methods are available for rapid and simple NA subtyping. Here we developed a multiplex probe combination-based one-step real-time reverse transcriptase PCR (rRT-PCR) to detect nine avian influenza virus NA subtypes. Nine primer-probe pairs were assigned to three groups based on the different fluorescent dyes of the probes (FAM, HEX, or Texas Red). Each probe detected only one NA subtype, without cross reactivity. The detection limit was less than 100 EID 50 or 100 copies of cDNA per reaction. Data obtained using this method with allantoic fluid samples isolated from live bird markets and H9N2-infected chickens correlated well with data obtained using virus isolation and sequencing, but was more sensitive. This new method provides a specific and sensitive alternative to conventional NA-subtyping methods.

TNF α is involved in neuropathic pain induced by nucleoside reverse transcriptase inhibitor in rats

PubMed Central

Zheng, Xuexing; Ouyang, Handong; Liu, Shue; Mata, Marina; Fink, David J.; Hao, Shuanglin

2011-01-01

In patients with HIV/AIDS, neuropathic pain is a common neurological complication. Infection with the HIV itself may lead to neuropathic pain, and painful symptoms are enhanced when patients are treated with nucleoside reverse transcriptase inhibitors (NRTI). The mechanisms by which NRTIs contribute to the development of neuropathic pain are not known. In the current studies, we tested the role of TNFα in antiretroviral drug-induced neuropathic pain. We administered 2′,3′-dideoxycytidine (ddC, one of the NRTIs) systemically to induce mechanical allodynia. We found that ddC induced overexpression of both mRNA and proteins of GFAP and TNFα in the spinal dorsal horn. TNFα was colocalized with GFAP in the spinal dorsal horn and with NeuN in the DRG. Knockdown of TNFα with siRNA blocked the mechanical allodynia induced by ddC. Intrathecal administration of glial inhibitor or recombinant TNF soluble receptor, reversed mechanical allodynia induced by ddC. These results suggest that TNFα is involved in NRTI-induced neuropathic pain. PMID:21741472

Mitochondrial DNA replication, nucleoside reverse-transcriptase inhibitors, and AIDS cardiomyopathy.

PubMed

Lewis, William

2003-01-01

Nucleoside reverse-transcriptase inhibitors (NRTIs) in combination with other antiretrovirals (HAART) are the cornerstones of current AIDS therapy, but extensive use brought mitochondrial side effects to light. Clinical experience, pharmacological, cell, and molecular biological evidence links altered mitochondrial (mt-) DNA replication to the toxicity of NRTIs in many tissues, and conversely, mtDNA replication defects and mtDNA depletion in target tissues are observed. Organ-specific pathological changes or diverse systemic effects result from and are frequently attributed to HAART in which NRTIs are included. The shared features of mtDNA depletion and energy depletion became key observations and related the clinical and in vivo experimental findings to inhibition of mtDNA replication by NRTI triphosphates in vitro. Subsequent to those findings, other observations suggested that mitochondrial energy deprivation is concomitant with or the result of mitochondrial oxidative stress in AIDS (from HIV, for example) or from NRTI therapy itself. Copyright 2003, Elsevier Science (USA)

Towards novel therapeutics for HIV through fragment-based screening and drug design.

PubMed

Tiefendbrunn, Theresa; Stout, C David

2014-01-01

Fragment-based drug discovery has been applied with varying levels of success to a number of proteins involved in the HIV (Human Immunodeficiency Virus) life cycle. Fragment-based approaches have led to the discovery of novel binding sites within protease, reverse transcriptase, integrase, and gp41. Novel compounds that bind to known pockets within CCR5 have also been identified via fragment screening, and a fragment-based approach to target the TAR-Tat interaction was explored. In the context of HIV-1 reverse transcriptase (RT), fragment-based approaches have yielded fragment hits with mid-μM activity in an in vitro activity assay, as well as fragment hits that are active against drug-resistant variants of RT. Fragment-based drug discovery is a powerful method to elucidate novel binding sites within proteins, and the method has had significant success in the context of HIV proteins.

Fragment Screening and HIV Therapeutics

PubMed Central

Bauman, Joseph D.; Patel, Disha; Arnold, Eddy

2013-01-01

Fragment screening has proven to be a powerful alternative to traditional methods for drug discovery. Biophysical methods, such as X-ray crystallography, NMR spectroscopy, and surface plasmon resonance, are used to screen a diverse library of small molecule compounds. Although compounds identified via this approach have relatively weak affinity, they provide a good platform for lead development and are highly efficient binders with respect to their size. Fragment screening has been utilized for a wide-range of targets, including HIV-1 proteins. Here, we review the fragment screening studies targeting HIV-1 proteins using X-ray crystallography or surface plasmon resonance. These studies have successfully detected binding of novel fragments to either previously established or new sites on HIV-1 protease and reverse transcriptase. In addition, fragment screening against HIV-1 reverse transcriptase has been used as a tool to better understand the complex nature of ligand binding to a flexible target. PMID:21972022

An Intravaginal Ring That Releases the NNRTI MIV-150 Reduces SHIV Transmission in Macaques

PubMed Central

Rodriguez, Aixa; Kizima, Larisa; Menon, Radhika; Goldman, Daniel; Kenney, Jessica; Aravantinou, Meropi; Seidor, Samantha; Gettie, Agegnehu; Blanchard, James; Piatak, Michael; Lifson, Jeffrey D.; Fernández-Romero, José A.; Robbiani, Melissa; Zydowsky, Thomas M.

2015-01-01

Microbicides may prevent HIV and sexually transmitted infections (STIs) in women; however, determining the optimal means of delivery of active pharmaceutical ingredients remains a major challenge. We previously demonstrated that a vaginal gel containing the non-nucleoside reverse transcriptase inhibitor MIV-150 partially protected macaques from SHIV-RT (simian/HIV reverse transcriptase) infection, and the addition of zinc acetate rendered the gel significantly protective. We test the activity of MIV-150 without the addition of zinc acetate when delivered from either ethylene vinyl acetate (EVA) or silicone intravaginal rings (IVRs). MIV-150 was successfully delivered, because it was detected in vaginal fluids and tissues by radioimmunoassay in pharmacokinetic studies. Moreover, EVA IVRs significantly protected macaques from SHIV-RT infection. Our results demonstrate that MIV-150–containing IVRs have the potential to prevent HIV infection and highlight the possible use of IVRs for delivering drugs that block HIV and other STIs. PMID:22956201

An intravaginal ring that releases the NNRTI MIV-150 reduces SHIV transmission in macaques.

PubMed

Singer, Rachel; Mawson, Paul; Derby, Nina; Rodriguez, Aixa; Kizima, Larisa; Menon, Radhika; Goldman, Daniel; Kenney, Jessica; Aravantinou, Meropi; Seidor, Samantha; Gettie, Agegnehu; Blanchard, James; Piatak, Michael; Lifson, Jeffrey D; Fernández-Romero, José A; Robbiani, Melissa; Zydowsky, Thomas M

2012-09-05

Microbicides may prevent HIV and sexually transmitted infections (STIs) in women; however, determining the optimal means of delivery of active pharmaceutical ingredients remains a major challenge. We previously demonstrated that a vaginal gel containing the non-nucleoside reverse transcriptase inhibitor MIV-150 partially protected macaques from SHIV-RT (simian/HIV reverse transcriptase) infection, and the addition of zinc acetate rendered the gel significantly protective. We test the activity of MIV-150 without the addition of zinc acetate when delivered from either ethylene vinyl acetate (EVA) or silicone intravaginal rings (IVRs). MIV-150 was successfully delivered, because it was detected in vaginal fluids and tissues by radioimmunoassay in pharmacokinetic studies. Moreover, EVA IVRs significantly protected macaques from SHIV-RT infection. Our results demonstrate that MIV-150-containing IVRs have the potential to prevent HIV infection and highlight the possible use of IVRs for delivering drugs that block HIV and other STIs.

Practical diagnostic testing for human immunodeficiency virus.

PubMed Central

Jackson, J B; Balfour, H H

1988-01-01

Since the discovery of human immunodeficiency virus (HIV) as the causative agent of acquired immunodeficiency syndrome in 1983, there has been a proliferation of diagnostic tests. These assays can be used to detect the presence of HIV antibody, HIV antigen, HIV ribonucleic and deoxyribonucleic acids, and HIV reverse transcriptase. Enzyme-linked immunosorbent assays, Western blot, radioimmunoprecipitation assays, indirect immunofluorescence assays, reverse transcriptase assays, and several molecular hybridization techniques are currently available. Enzyme-linked immunosorbent, Western blot, and indirect immunofluorescence assays for HIV antibody are very sensitive, specific, and adaptable to most laboratories. An enzyme-linked immunosorbent assay for HIV antigen is also readily adaptable to most laboratories and will be commercially available soon. While the other assays are more tedious, they are valuable confirmatory tests and are suitable for reference laboratories. The biohazards of performing HIV testing can be minimized with proper biosafety measures. Images PMID:3060241

Telomerase Mechanism of Telomere Synthesis

PubMed Central

Wu, R. Alex; Upton, Heather E.; Vogan, Jacob M.; Collins, Kathleen

2017-01-01

Telomerase is the essential reverse transcriptase required for linear chromosome maintenance in most eukaryotes. Telomerase supplements the tandem array of simple-sequence repeats at chromosome ends to compensate for the DNA erosion inherent in genome replication. The template for telomerase reverse transcriptase is within the RNA subunit of the ribonucleoprotein complex, which in cells contains additional telomerase holoenzyme proteins that assemble the active ribonucleoprotein and promote its function at telomeres. Telomerase is distinct among polymerases in its reiterative reuse of an internal template. The template is precisely defined, processively copied, and regenerated by release of single-stranded product DNA. New specificities of nucleic acid handling that underlie the catalytic cycle of repeat synthesis derive from both active site specialization and new motif elaborations in protein and RNA subunits. Studies of telomerase provide unique insights into cellular requirements for genome stability, tissue renewal, and tumorigenesis as well as new perspectives on dynamic ribonucleoprotein machines. PMID:28141967

Human telomerase reverse transcriptase is a promising target for cancer inhibition in squamous cell carcinomas.

PubMed

Park, Young-Jin; Kim, Eun-Kyoung; Moon, Sook; Hong, Doo-Pyo; Bae, Jung Yoon; Kim, Jin

2014-11-01

The present study aimed to investigate whether the down-regulation of human telomerase reverse transcriptase (hTERT) may induce an anti-invasive effect in oral squamous cell cancer cell lines. A genetically-engineered squamous carcinoma cell line overexpressing hTERT in immortalized oral keratinocytes transfected by human papilloma virus (HPV)-16 E6/E7 (IHOK) was used. In vivo tumorigenicity was examined using an orthotopic xenograft model of nude mice. For evaluating anti-invasive activity by knockdown of hTERT expression, transwell invasion assay and real-time polymerase chain reaction (PCR) for matrix metalloproteinases (MMP) were employed. The down-regulation of hTERT expression reduced the invasive activity and MMP expression. This result was re-confirmed in the HSC3 oral squamous carcinoma cell line. Targeting hTERT may lead to novel therapeutic approaches. Copyright© 2014 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

A full-coordinate model of the polymerase domain of HIV-1 reverse transcriptase and its interaction with a nucleic acid substrate

NASA Technical Reports Server (NTRS)

Setlik, R. F.; Meyer, D. J.; Shibata, M.; Roskwitalski, R.; Ornstein, R. L.; Rein, R.

1994-01-01

We present a full-coordinate model of residues 1-319 of the polymerase domain of HIV-I reverse transcriptase. This model was constructed from the x-ray crystallographic structure of Jacobo-Molina et al. (Jacobo-Molina et al., P.N.A.S. USA 90, 6320-6324 (1993)) which is currently available to the degree of C-coordinates. The backbone and side-chain atoms were constructed using the MAXSPROUT suite of programs (L. Holm and C. Sander, J. Mol. Biol. 218, 183-194 (1991)) and refined through molecular modeling. A seven base pair A-form dsDNA was positioned in the nucleic acid binding cleft to represent the template-primer complex. The orientation of the template-primer complex in the nucleic acid binding cleft was guided by the positions of phosphorus atoms in the crystal structure.

Occurrence of etravirine/rilpivirine-specific resistance mutations selected by efavirenz and nevirapine in Kenyan patients with non-B HIV-1 subtypes failing antiretroviral therapy.

PubMed

Crawford, Keith W; Njeru, Dorothy; Maswai, Jonah; Omondi, Milton; Apollo, Duncan; Kimetto, Jane; Gitonga, Lawrence; Munyao, James; Langat, Raphael; Aoko, Appolonia; Tarus, Jemutai; Khamadi, Samoel; Hamm, Tiffany E

2014-01-28

Resistance to efavirenz and nevirapine has not been associated with mutations at position 138 of reverse transcriptase. In an evaluation of virologic suppression rates in PEPFAR (President's Emergency Plan For AIDS Relief) clinics in Kenya among patients on first-line therapy (RV288), 63% (617/975) of randomly selected patients on antiretroviral therapy were suppressed (HIV RNA<400 copies/ml). Among those with non-nucleoside reverse transcriptase inhibitor resistance (n = 101), 14 (13.8%) had substitutions at 138 (A, G, K or Q), mutations selected only by etravirine and rilpivirine in subtype B viruses. All 14 patients received efavirenz or nevirapine, not etravirine or rilpivirine, and were predominantly subtype A1. This may be the first report of efavirenz and nevirapine selecting these mutations in these subtypes.

HIV type 1 diversity in the Seychelles.

PubMed

Razafindratsimandresy, Richter; Hollanda, Justina; Soares, Jean-Louis; Rousset, Dominique; Chetty, Agnes P; Reynes, Jean-Marc

2007-06-01

Subtype determination and drug resistance-associated mutations (DRM) detection were performed on 40 HIV-1 Western blot-positive sera detected, obtained from consecutive patients resident in the Seychelles and consulting the Communicable Disease Control Unit, HIV reference center, in Victoria Hospital (Mahe) from October 2005 to June 2006. Amplification and sequencing of at least two of the partial reverse transcriptase, protease, and partial envelope genes were successful for all strains. All three genes sequences were obtained for 39 strains. A high degree of subtype or circulating recombinant forms (CRF) was observed for these 39 strains: A-A1 (17 cases), C (10 cases), B (8 cases), CRF02_AG (2 cases), D (1 case) and CRF01_AE (1 case). According to the ANRS 2006 DRM list and algorithm, none of the 40 isolates was found to be resistant to any protease or reverse transcriptase inhibitors.

Synthesis, biological evaluation and molecular modeling of 2-Hydroxyisoquinoline-1,3-dione analogues as inhibitors of HIV reverse transcriptase associated ribonuclease H and polymerase.

PubMed

Tang, Jing; Vernekar, Sanjeev Kumar V; Chen, Yue-Lei; Miller, Lena; Huber, Andrew D; Myshakina, Nataliya; Sarafianos, Stefan G; Parniak, Michael A; Wang, Zhengqiang

2017-06-16

Human immunodeficiency virus (HIV) reverse transcriptase (RT) associated ribonuclease H (RNase H) remains the only virally encoded enzymatic function not clinically validated as an antiviral target. 2-Hydroxyisoquinoline-1,3-dione (HID) is known to confer active site directed inhibition of divalent metal-dependent enzymatic functions, such as HIV RNase H, integrase (IN) and hepatitis C virus (HCV) NS5B polymerase. We report herein the synthesis and biochemical evaluation of a few C-5, C-6 or C-7 substituted HID subtypes as HIV RNase H inhibitors. Our data indicate that while some of these subtypes inhibited both the RNase H and polymerase (pol) functions of RT, potent and selective RNase H inhibition was achieved with subtypes 8-9 as exemplified with compounds 8c and 9c. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Transposable elements in sexual and ancient asexual taxa

PubMed Central

Arkhipova, Irina; Meselson, Matthew

2000-01-01

Sexual reproduction allows deleterious transposable elements to proliferate in populations, whereas the loss of sex, by preventing their spread, has been predicted eventually to result in a population free of such elements [Hickey, D. A. (1982) Genetics 101, 519–531]. We tested this expectation by screening representatives of a majority of animal phyla for LINE-like and gypsy-like reverse transcriptases and mariner/Tc1-like transposases. All species tested positive for reverse transcriptases except rotifers of the class Bdelloidea, the largest eukaryotic taxon in which males, hermaphrodites, and meiosis are unknown and for which ancient asexuality is supported by molecular genetic evidence. Mariner-like transposases are distributed sporadically among species and are present in bdelloid rotifers. The remarkable lack of LINE-like and gypsy-like retrotransposons in bdelloids and their ubiquitous presence in other taxa support the view that eukaryotic retrotransposons are sexually transmitted nuclear parasites and that bdelloid rotifers evolved asexually. PMID:11121049

Naringin enhances reverse cholesterol transport in high fat/low streptozocin induced diabetic rats.

PubMed

Rotimi, Solomon Oladapo; Adelani, Isaacson Bababode; Bankole, Goodness Esther; Rotimi, Oluwakemi Anuoluwapo

2018-05-01

Naringin, a citrus-derived flavonoid with antihyperglycemic, antihyperlipidemic, and antioxidant properties, is reported to be a useful nutraceutical in the management of diabetes and its complications. This study investigated the mechanism of antiatherogenic properties of naringin in type 2 diabetes (T2DM) using high fat-low streptozocin rat model of T2DM. Rats were treated daily with 50, 100 and 200 mg/kg naringin orally for 21days. Levels of biomarkers of T2DM, lipid profile and activity of paraoxonase (PON) were assayed spectrophotometrically. The levels of expression of hepatic 3-hydroxy-3-methyl-glutaryl-CoA reductase (Hmgcr), scavenger receptor class B member 1 (Scarb1), aryl hydrocarbon receptor (Ahr), hepatic Lipase (Lipc), and lecithin-cholesterol acyltransferase (Lcat) were assessed using relative reverse transcriptase polymerase chain reaction technique. Naringin treatment resulted in a dose-dependent significant (p < 0.05) decrease in the levels of plasma cholesterol and triglyceride from 84.84 ± 1.62 to 55.59 ± 1.50 mg/dL and 123.03 ± 15.11 to 55.00 ± 0.86 mg/dL, respectively, at 200 mg/kg naringin. In the liver, Scarb1 and Ahr were significantly (p < 0.05) upregulated at 200 mg/kg naringin while Lipc and Lcat were significantly (p < 0.05) upregulated by 50 mg/kg naringin. T2DM-induced decrease in PON activities in the plasma, liver and HDL was significantly (p < 0.05) reversed by 200 mg/kg naringin treatment. These genes play critical roles in reverse cholesterol transport and hence our results showed that the antiatherogenic property of naringin in T2DM involves enhancement of reverse cholesterol transport and PON activity. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Effect of substituted benzimidazoles on acid secretion in isolated and enriched guinea pig parietal cells.

PubMed Central

Sewing, K F; Harms, P; Schulz, G; Hannemann, H

1983-01-01

The inhibitory effect of the three benzimidazole derivatives timoprazole, picoprazole, and omeprazole on histamine and dbcAMP stimulated 14C-aminopyrine accumulation (= H+ secretion) has been studied in isolated and enriched guinea-pig parietal cells. All compounds tested inhibited H+ secretion in a concentration dependent manner with IC50 values of 8.5 +/- 1.9 mumol/l for timoprazole, 3.9 +/- 0.7 mumol/l for picoprazole, and 0.13 +/- 0.03 mumol/l for omeprazole. The IC50 of timoprazole, when dbcAMP was used as a stimulus, did not differ significantly from that of histamine stimulation. The type of inhibition was of a non-competitive nature. The full acid response to histamine after temporary exposure of the cells to the benzimidazoles could be restored by washing the cells twice; this suggests that the inhibition is reversible. The data - among others - indicate that the properties of the benzimidazoles described here would allow these compounds to be used as effective antisecretagogues. PMID:6303916

Separation and Characterization of Angiotensin I Converting Enzyme (ACE) Inhibitory Peptides from Saurida elongata Proteins Hydrolysate by IMAC-Ni2.

PubMed

Sun, Lixia; Wu, Shanguang; Zhou, Liqin; Wang, Feng; Lan, Xiongdiao; Sun, Jianhua; Tong, Zhangfa; Liao, Dankui

2017-02-15

Lizard fish protein hydrolysates (LFPH) were prepared from Lizard fish ( Saurida elongata ) proteins possessing powerful angiotensin I converting enzyme (ACE) inhibitory activity and the fraction (LFPH-I) with high ACE inhibitory activity was obtained through ultrafiltration. The active Fraction (F2) was isolated from LFPH-I using immobilized metal affinity chromatography (IMAC - Ni 2+ ). Analysis of amino acid levels revealed that F2 eluted from IMAC was enriched in Met, His, Tyr, Pro, Ile, and Leu compared to the crude peptide LFPH-I. F2 with the high ACE inhibitory activity (IC 50 of 0.116 mg·mL -1 ) was further separated by a reverse-phase column to yield a novel ACE inhibitory peptide with IC 50 value of 52 μM. The ACE inhibitory peptide was identified as Arg-Tyr-Arg-Pro, RYRP. The present study demonstrated that IMAC may be a useful tool for the separation of ACE inhibitory peptides from protein hydrolysate.

Isolation of prolyl endopeptidase inhibitory peptides from a sodium caseinate hydrolysate.

PubMed

Hsieh, Cheng-Hong; Wang, Tzu-Yuan; Hung, Chuan-Chuan; Hsieh, You-Liang; Hsu, Kuo-Chiang

2016-01-01

Prolyl endopeptidase (PEP) has been associated with neurodegenerative disorders, and the PEP inhibitors can restore the memory loss caused by amnesic compounds. In this study, we investigated the PEP inhibitory activity of the enzymatic hydrolysates from various food protein sources, and isolated and identified the PEP inhibitory peptides. The hydrolysate obtained from sodium caseinate using bromelain (SC/BML) displayed the highest inhibitory activity of 86.8% at 5 mg mL(-1) in the present study, and its IC50 value against PEP was 0.77 mg mL(-1). The F-5 fraction by RP-HPLC (reversed-phase high performance liquid chromatography) from SC/BML showed the highest PEP inhibition rate of 88.4%, and 9 peptide sequences were identified. The synthetic peptides (1245.63-1787.94 Da) showed dose-dependent inhibition effects on PEP as competitive inhibitors with IC50 values between 29.8 and 650.5 μM. The results suggest that the peptides derived from sodium caseinate have the potential to be PEP inhibitors.

Fragment Based Strategies for Discovery of Novel HIV-1 Reverse Transcriptase and Integrase Inhibitors.

PubMed

Latham, Catherine F; La, Jennifer; Tinetti, Ricky N; Chalmers, David K; Tachedjian, Gilda

2016-01-01

Human immunodeficiency virus (HIV) remains a global health problem. While combined antiretroviral therapy has been successful in controlling the virus in patients, HIV can develop resistance to drugs used for treatment, rendering available drugs less effective and limiting treatment options. Initiatives to find novel drugs for HIV treatment are ongoing, although traditional drug design approaches often focus on known binding sites for inhibition of established drug targets like reverse transcriptase and integrase. These approaches tend towards generating more inhibitors in the same drug classes already used in the clinic. Lack of diversity in antiretroviral drug classes can result in limited treatment options, as cross-resistance can emerge to a whole drug class in patients treated with only one drug from that class. A fresh approach in the search for new HIV-1 drugs is fragment-based drug discovery (FBDD), a validated strategy for drug discovery based on using smaller libraries of low molecular weight molecules (<300 Da) screened using primarily biophysical assays. FBDD is aimed at not only finding novel drug scaffolds, but also probing the target protein to find new, often allosteric, inhibitory binding sites. Several fragment-based strategies have been successful in identifying novel inhibitory sites or scaffolds for two proven drug targets for HIV-1, reverse transcriptase and integrase. While any FBDD-generated HIV-1 drugs have yet to enter the clinic, recent FBDD initiatives against these two well-characterised HIV-1 targets have reinvigorated antiretroviral drug discovery and the search for novel classes of HIV-1 drugs.

Molecular docking of (5E)-3-(2-aminoethyl)-5-(2- thienylmethylene)-1, 3-thiazolidine-2, 4-dione on HIV-1 reverse transcriptase: novel drug acting on enzyme.

PubMed

Seniya, Chandrabhan; Yadav, Ajay; Uchadia, Kuldeep; Kumar, Sanjay; Sagar, Nitin; Shrivastava, Priyanka; Shrivastava, Shilpi; Wadhwa, Gulshan

2012-01-01

The study of Human immunodeficiency virus (HIV) in humans and animal models in last 31 years suggested that it is a causative agent of AIDS. This causes serious pandemic public health concern globally. It was reported that the HIV-1 reverse transcriptase (RT) played a critical role in the life cycle of HIV. Therefore, inhibition of HIV-1RT enzyme is one of the major and potential targets in the treatment of AIDS. The enzyme (HIV-1RT) was successfully targeted by non nucleotide reverse transcriptase inhibitors (NNRTIs). But frequent application of NNRTIs led drug resistance mutation on HIV infections. Therefore, there is a need to search new NNRTIs with appropriate pharmacophores. For the purpose, a virtually screened 3D model of unliganded HIV-1RT (1DLO) was explored. The unliganded HIV-1RT (1DLO) was docked with 4-thiazolidinone and its derivatives (ChemBank Database) by using AutoDock4. The best seven docking solutions complex were selected and analyzed by Ligplot. The analysis showed that derivative (5E)-3-(2- aminoethyl)-5-(2- thienylmethylene)-1, 3-thiazolidine-2, 4-dione (CID 3087795) has maximum potential against unliganded HIV-1RT (1DLO). The analysis was done on the basis of scoring and binding ability. The derivative (5E)-3-(2- aminoethyl)-5-(2- thienylmethylene)-1, 3-thiazolidine-2, 4-dione (CID 3087795) indicated minimum energy score and highest number of interactions with active site residue and could be a promising inhibitor for HIV-1 RT as Drug target.

Antiretroviral therapy in children: recent advances.

PubMed

Lodha, Rakesh; Manglani, Mamta

2012-12-01

Availability and successful use of various antiretroviral drugs has transformed HIV/AIDS from an incurable to a treatable chronic condition. The antiretroviral therapy can successfully suppress viral replication and preserve the immune system for many years. The implementation of antiretroviral therapy program in resource limited settings using the 'public health approach' of the World Health Organization has had a dramatic impact on the lives of millions of HIV infected individuals. Antiretroviral therapy (ART) in children has many challenges: use of appropriate formulations, regular need for modification of doses as the child grows, adherence issues, etc. To reduce the high morbidity and mortality in HIV infected children, it is currently recommended that all HIV infected children less than 24 mo should receive ART; in older children the indications are based on clinical and/or immunological criteria. Highly active antiretroviral therapy regimens include at least 3 antiretroviral drugs. The first line therapy recommended for children is a combination of two nucleoside reverse transcriptase inhibitors and a non-nucleoside reverse transcriptase inhibitor. Infants who have had exposure to nevirapine should receive a combination of two nucleoside reverse transcriptase inhibitors and a protease inhibitor; the protease inhibitor of choice is ritonavir boosted lopinavir. The success of therapy is dependent on >95 % adherence. The second line regimen, used when the first line therapy fails, is based on a protease inhibitor. The ongoing research focuses on simplification of regimen, discovery of more potent drugs, availability of more pediatric formulations, treatment of drug resistant strains etc. The optimal indications for initiation of therapy in children, are also being studied.

Screening for diverse PDGFRA or PDGFRB fusion genes is facilitated by generic quantitative reverse transcriptase polymerase chain reaction analysis

PubMed Central

Erben, Philipp; Gosenca, Darko; Müller, Martin C.; Reinhard, Jelena; Score, Joannah; del Valle, Francesco; Walz, Christoph; Mix, Jürgen; Metzgeroth, Georgia; Ernst, Thomas; Haferlach, Claudia; Cross, Nicholas C.P.; Hochhaus, Andreas; Reiter, Andreas

2010-01-01

Background Rapid identification of diverse fusion genes with involvement of PDGFRA or PDGFRB in eosinophilia-associated myeloproliferative neoplasms is essential for adequate clinical management but is complicated by the multitude and heterogeneity of partner genes and breakpoints. Design and Methods We established a generic quantitative reverse transcriptase polymerase chain reaction to detect overexpression of the 3′-regions of PDGFRA or PDGFRB as a possible indicator of an underlying fusion. Results At diagnosis, all patients with known fusion genes involving PDGFRA (n=5; 51 patients) or PDGFRB (n=5; 7 patients) showed significantly increased normalized expression levels compared to 191 patients with fusion gene-negative eosinophilia or healthy individuals (PDGFRA/ABL: 0.73 versus 0.0066 versus 0.0064, P<0.0001; PDGFRB/ABL: 196 versus 3.8 versus 5.85, P<0.0001). The sensitivity and specificity of the activation screening test were, respectively, 100% and 88.4% for PDGFRA and 100% and 94% for PDGFRB. Furthermore, significant overexpression of PDGFRB was found in a patient with an eosinophilia-associated myeloproliferative neoplasm with uninformative cytogenetics and an excellent response to imatinib. Subsequently, a new SART3-PDGFRB fusion gene was identified by 5′-rapid amplification of cDNA ends polymerase chain reaction (5′-RACE-PCR). Conclusions Quantitative reverse transcriptase polymerase chain reaction analysis is a simple and useful adjunct to standard diagnostic assays to detect clinically significant overexpression of PDGFRA and PDGFRB in eosinophilia-associated myeloproliferative neoplasms or related disorders. PMID:20107158

Analytical validation of a reverse transcriptase droplet digital PCR (RT-ddPCR) for quantitative detection of infectious hematopoietic necrosis virus

USGS Publications Warehouse

Jia, Peng; Purcell, Maureen; Pan, Guang; Wang, Jinjin; Kan, Shifu; Liu, Yin; Zheng, Xiaocong; SHi, Xiujie; He, Junqiang; Yu, Li; Hua, Qunyi; Lu, Tikang; Lan, Wensheng; Winton, James; Jin, Ningyi; Liu, Hong

2017-01-01

Infectious hematopoietic necrosis virus (IHNV) is an important pathogen of salmonid fishes. A validated universal reverse transcriptase quantitative PCR (RT-qPCR) assay that can quantify levels of IHNV in fish tissues has been previously reported. In the present study, we adapted the published set of IHNV primers and probe for use in a reverse-transcriptase droplet digital PCR (RT-ddPCR) assay for quantification of the virus in fish tissue samples. The RT-ddPCR and RT-qPCR assays detected 13 phylogenetically diverse IHNV strains, but neither assay produced detectable amplification when RNA from other fish viruses was used. The RT-ddPCR assay had a limit of detection (LOD) equating to 2.2 plaque forming units (PFU)/μl while the LOD for the RT-qPCR was 0.2 PFU/μl. Good agreement (69.4–100%) between assays was observed when used to detect IHNV RNA in cell culture supernatant and tissues from IHNV infected rainbow trout (Oncorhynchus mykiss) and arctic char (Salvelinus alpinus). Estimates of RNA copy number produced by the two assays were significantly correlated but the RT-qPCR consistently produced higher estimates than the RT-ddPCR. The analytical properties of the N gene RT-ddPCR test indicated that this method may be useful to assess IHNV RNA copy number for research and diagnostic purposes. Future work is needed to establish the within and between laboratory diagnostic performance of the RT-ddPCR assay.

Application of Receiver Operating Characteristic Analysis to Refine the Prediction of Potential Digoxin Drug Interactions

PubMed Central

Ellens, Harma; Deng, Shibing; Coleman, JoAnn; Bentz, Joe; Taub, Mitchell E.; Ragueneau-Majlessi, Isabelle; Chung, Sophie P.; Herédi-Szabó, Krisztina; Neuhoff, Sibylle; Palm, Johan; Balimane, Praveen; Zhang, Lei; Jamei, Masoud; Hanna, Imad; O’Connor, Michael; Bednarczyk, Dallas; Forsgard, Malin; Chu, Xiaoyan; Funk, Christoph; Guo, Ailan; Hillgren, Kathleen M.; Li, LiBin; Pak, Anne Y.; Perloff, Elke S.; Rajaraman, Ganesh; Salphati, Laurent; Taur, Jan-Shiang; Weitz, Dietmar; Wortelboer, Heleen M.; Xia, Cindy Q.; Xiao, Guangqing; Yamagata, Tetsuo

2013-01-01

In the 2012 Food and Drug Administration (FDA) draft guidance on drug-drug interactions (DDIs), a new molecular entity that inhibits P-glycoprotein (P-gp) may need a clinical DDI study with a P-gp substrate such as digoxin when the maximum concentration of inhibitor at steady state divided by IC50 ([I1]/IC50) is ≥0.1 or concentration of inhibitor based on highest approved dose dissolved in 250 ml divide by IC50 ([I2]/IC50) is ≥10. In this article, refined criteria are presented, determined by receiver operating characteristic analysis, using IC50 values generated by 23 laboratories. P-gp probe substrates were digoxin for polarized cell-lines and N-methyl quinidine or vinblastine for P-gp overexpressed vesicles. Inhibition of probe substrate transport was evaluated using 15 known P-gp inhibitors. Importantly, the criteria derived in this article take into account variability in IC50 values. Moreover, they are statistically derived based on the highest degree of accuracy in predicting true positive and true negative digoxin DDI results. The refined criteria of [I1]/IC50 ≥ 0.03 and [I2]/IC50 ≥ 45 and FDA criteria were applied to a test set of 101 in vitro-in vivo digoxin DDI pairs collated from the literature. The number of false negatives (none predicted but DDI observed) were similar, 10 and 12%, whereas the number of false positives (DDI predicted but not observed) substantially decreased from 51 to 40%, relative to the FDA criteria. On the basis of estimated overall variability in IC50 values, a theoretical 95% confidence interval calculation was developed for single laboratory IC50 values, translating into a range of [I1]/IC50 and [I2]/IC50 values. The extent by which this range falls above the criteria is a measure of risk associated with the decision, attributable to variability in IC50 values. PMID:23620486

TELOMERASE AND CHRONIC ARSENIC EXPOSURE IN HUMANS

EPA Science Inventory

Arsenic exposure has been associated with increased risk of skin, lung and bladder cancer in humans. The mechanisms of carcinogenesis are not well understood. Telomerase, a ribonucleoprotein containing human telomerase reverse transcriptase (hTERT), can extend telomeres of eukary...

Synthesis and β-glucuronidase inhibitory potential of benzimidazole derivatives.

PubMed

Khan, Khalid Mohammed; Khan, Momin; Ambreen, Nida; Rahim, Fazal; Naureen, Shagufta; Perveen, Shahnaz; Choudhary, M Iqbal; Voelter, Wolfgang

2012-05-01

Benzimidazole derivatives 1-24 have been synthesized and their in vitro β-glucuronidase inhibitory activitiy was evaluated. Compounds 15 (IC50=6.33+/-0.40 μM), 7 (IC50=22.0+/-0.33 μM), 2 (IC50=23.1+/-1.78 μM), 17 (IC50=23.9+/-1.46 μM), and 3 (IC50=33.8+/-1.61 μM) showed more potent β-glucuronidase inhibitory activity than the standard (D-saccharic acid 1,4 lactone, IC50=48.4+/-1.25 μM). This study has identified a new series of potential β-glucuronidase inhibitors. A structure-activity relationship has also been studied.

A reverse transcriptase-dependent mechanism plays central roles in fundamental biological processes.

PubMed

Spadafora, Corrado

2008-01-01

This review summarizes emerging evidence that LINE-1 (Long Interspersed Nuclear Elements) -encoded reverse transcriptase (RT) regulates fundamental biological processes. Earlier studies showed that sperm cells can be used as vectors of both exogenous DNA and RNA molecules in sperm-mediated gene transfer assays. During these studies, a sperm endogenous RT activity was identified, which can reverse-transcribe exogenous RNA directly, or DNA molecules through sequential transcription and reverse transcription. Resulting cDNA copies generated in sperm cells can be delivered to embryos at fertilization, further propagated in tissues as low-copy extrachromosomal structures and transmitted to the progeny in a non-mendelian fashion. Being transcriptionally competent, they can induce phenotypic variations in positive tissues. An RT activity is also present in preimplantation embryos, and its inhibition causes developmental arrest in early preimplantation stages, paralleled by an extensive reprogramming of gene expression. In analogy with this, drug-mediated inhibition of RT activity, or RNA interference-mediated silencing of human LINE-1, reduce cell proliferation and induce differentiation in a variety of cancer cell lines. Furthermore, RT inhibition in vivo antagonizes the growth of human tumors in animal models. As a whole, these data implicate a RT-dependent machinery in the genesis of new genetic information in spermatozoa and in normal and pathological developmental processes.

Development and validation of a rapid reversed-phase HPLC method for the determination of the non-nucleoside reverse transcriptase inhibitor dapivirine from polymeric nanoparticles.

PubMed

das Neves, José; Sarmento, Bruno; Amiji, Mansoor M; Bahia, Maria Fernanda

2010-06-05

The objective of this work was to develop and validate a rapid reversed-phase (RP) high-performance liquid chromatography (HPLC) method for the in vitro pharmaceutical characterization of dapivirine-loaded polymeric nanoparticles. Chromatographic runs were performed on a RP C18 column with a mobile phase comprising acetonitrile-0.5% (w/v) triethanolamine solution in isocratic mode (80:20, v/v) at a flow rate of 1 ml/min. Dapivirine was detected at a wavelength of 290 nm. The method was shown to be specific, linear in the range of 1-50 microg/ml (R(2)=0.9998), precise at the intra-day and inter-day levels as reflected by the relative standard deviation values (less than 0.85%), accurate (recovery rate of 100.17+/-0.35%), and robust to changes in the mobile phase and column brand. The detection and quantitation limits were 0.08 and 0.24 microg/ml, respectively. The method was successfully used to determine the loading capacity and association efficiency of dapivirine in poly(lactic-co-glycolic acid)-based nanoparticles and its in vitro release. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Changed terms for drug payment influenced GPs' diagnoses and prescribing practice for inhaled corticosteroids.

PubMed

Dalbak, Lene G; Rognstad, Sture; Melbye, Hasse; Straand, Jørund

2013-06-01

Inhaled glucocorticosteroids (ICS) are first-line anti-inflammatory treatment in asthma, but not in chronic obstructive pulmonary disease (COPD). To restrict ICS use in COPD to cases of severe disease, new terms for reimbursement of drug costs were introduced in Norway in 2006, requiring a diagnosis of COPD to be verified by spirometry. To describe how GPs' diagnoses and treatment of patients who used ICS before 2006 changed after a reassessment of the patients that included spirometry. From the shared electronic patient record system in one group practice, patients ≥ 50 years prescribed ICS (including in combination with long-acting beta2-agonists) during the previous year were identified and invited to a tailored consultation including spirometry to assure the quality of diagnosis and treatment. GPs' diagnoses and ICS prescribing patterns after this reassessment were recorded, retrospectively. Of 164 patients identified, 112 were included. Post-bronchodilator spirometry showed airflow limitation indicating COPD in 55 patients. Of the 57 remaining patients, five had a positive reversibility test. The number of patients diagnosed with asthma increased (from 25 to 62) after the reassessment. A diagnosis of COPD was also more frequently used, whereas fewer patients had other pulmonary diagnoses. ICS was discontinued in 31 patients; 20 with mild to moderate COPD and 11 with normal spirometry. Altered reimbursement terms for ICS changed GPs' diagnostic practice in a way that made the diagnoses better fit with the treatment given, but over-diagnosis of asthma could not be excluded. Spirometry was useful for identifying ICS overuse.

Two novel assays for the detection of haemin-binding properties of antimalarials evaluated with compounds isolated from medicinal plants.

PubMed

Steele, J C P; Phelps, R J; Simmonds, M S J; Warhurst, D C; Meyer, D J

2002-07-01

Forty-two compounds isolated from nine plants used within South America for the treatment of malaria were tested for haemin binding using two novel, rapid screening methods. The data obtained were analysed with respect to IC(50) values for in vitro toxicity to Plasmodium falciparum trophozoites. One method, a multiwell assay based on the inhibition of the interaction of haemin with glutathione (GSH), is sensitive in the 10 microM range, takes c. 1 h and is suitable for either a high throughput screen or rapid assay during natural product isolation. Of 19 compounds showing antiplasmodial activity (IC(50) < 40 microM), 16 (84%) showed >40% inhibition of GSH-haemin reaction. The sensitivity and specificity of the assay were 0.85 and 0.82, respectively. The positive predictive value was 0.81 and the negative predictive value 0.86. A more sensitive assay (0.1 microM range) is based on the reversal by haemin-binding compounds of the haemin inhibition of the L-dopachrome-methyl ester tautomerase activity of human macrophage migration inhibitory factor. This assay gives a better idea of the affinity of interaction and uses very small amounts of test compound. The log[RI(50)] of eight of the compounds that tested positive in the above assays together with those of quinine and chloroquine showed a positive correlation with log[antiplasmodial IC(50)] for strain T9-96 (r = 0.824) and strain K1 (r = 0.904). Several of the antimalarial compounds that bind haemin are isoquinolines, a class not shown previously to interact with haemin.

Differences in resistance mutations among HIV-1 non-subtype B infections: a systematic review of evidence (1996–2008)

PubMed Central

2009-01-01

Ninety percent of HIV-1-infected people worldwide harbour non-subtype B variants of HIV-1. Yet knowledge of resistance mutations in non-B HIV-1 and their clinical relevance is limited. Although a few reviews, editorials and perspectives have been published alluding to this lack of data among non-B subtypes, no systematic review has been performed to date. With this in mind, we conducted a systematic review (1996–2008) of all published studies performed on the basis of non-subtype B HIV-1 infections treated with antiretroviral drugs that reported genotype resistance tests. Using an established search string, 50 studies were deemed relevant for this review. These studies reported genotyping data from non-B HIV-1 infections that had been treated with either reverse transcriptase inhibitors or protease inhibitors. While most major resistance mutations in subtype B were also found in non-B subtypes, a few novel mutations in non-B subtypes were recognized. The main differences are reflected in the discoveries that: (i) the non-nucleoside reverse transcriptase inhibitor resistance mutation, V106M, has been seen in subtype C and CRF01_AE, but not in subtype B, (ii) the protease inhibitor mutations L89I/V have been reported in C, F and G subtypes, but not in B, (iii) a nelfinavir selected non-D30N containing pathway predominated in CRF01_AE and CRF02_AG, while the emergence of D30N is favoured in subtypes B and D, (iv) studies on thymidine analog-treated subtype C infections from South Africa, Botswana and Malawi have reported a higher frequency of the K65R resistance mutation than that typically seen with subtype B. Additionally, some substitutions that seem to impact non-B viruses differentially are: reverse transcriptase mutations G196E, A98G/S, and V75M; and protease mutations M89I/V and I93L. Polymorphisms that were common in non-B subtypes and that may contribute to resistance tended to persist or become more frequent after drug exposure. Some, but not all, are recognized as minor resistance mutations in B subtypes. These observed differences in resistance pathways may impact cross-resistance and the selection of second-line regimens with protease inhibitors. Attention to newer drug combinations, as well as baseline genotyping of non-B isolates, in well-designed longitudinal studies with long duration of follow up are needed. PMID:19566959

Applications of 2D IR spectroscopy to peptides, proteins, and hydrogen-bond dynamics

PubMed Central

Kim, Yung Sam; Hochstrasser, Robin M.

2010-01-01

Following a survey of 2D IR principles this Feature Article describes recent experiments on the hydrogen-bond dynamics of small ions, amide-I modes, nitrile probes, peptides, reverse transcriptase inhibitors, and amyloid fibrils. PMID:19351162

Evaluation of Four RNA Extraction Methods for Gene Expression Analyses of Cryptosporidium parvum and Toxoplasma gondii Oocys

EPA Science Inventory

Cryptosporidium spp. and Toxoplasma gondii are important coccidian parasites that have caused waterborne and foodborne disease outbreaks worldwide. Techniques like subtractive hybridization, microarrays, and quantitative reverse transcriptase real-time polymerase chain reaction (...

Epigenetic Characterization of Ovarian Cancer

DTIC Science & Technology

2008-12-01

Gusberg, A. H., Whitaker, R. S., Gray , J. W., Fujii, S., Berchuck, A. and S. K. Murphy. YY1/E2F3 modulates antimicrotubule drug response in epithelial... GTG GGT TTT TGG TGT TGG GTA TT-3’; and a shared reverse primer that does not anneal to CpGs, 5’-AAC CCC ACT CCC ACC CTA CTC C-3’. PCR was performed...Superscript II RNase H- reverse transcriptase (Invitrogen). Forward primer: 5’-GCG ACA TCG GTG ACT TCA T-3’ and reverse primer 5’-ATA CAT GTC CGC CAG CTT

Quantitative expression profiling of immune response genes in rainbow trout following infectious haematopoietic necrosis virus (IHNV) infection or DNA vaccination

USGS Publications Warehouse

Purcell, Maureen K.; Kurath, Gael; Garver, Kyle A.; Herwig, Russell P.; Winton, James R.

2004-01-01

Infectious haematopoietic necrosis virus (IHNV) is a well-studied virus of salmonid fishes. A highly efficacious DNA vaccine has been developed against this virus and studies have demonstrated that this vaccine induces both an early and transient non-specific anti-viral phase as well as long-term specific protection. The mechanisms of the early anti-viral phase are not known, but previous studies noted changes in Mx gene expression, suggesting a role for type I interferon. This study used quantitative real-time reverse transcriptase PCR methodology to compare expression changes over time of a number of cytokine or cytokine-related genes in the spleen of rainbow trout following injection with poly I:C, live IHNV, the IHNV DNA vaccine or a control plasmid encoding the non-antigenic luciferase gene. The target genes included Mx-1, viral haemorrhagic septicaemia virus induced gene 8 (Vig-8), TNF-α1, TNF-α2, IL-1β1, IL-8, TGF-β1 and Hsp70. Poly I:C stimulation induced several genes but the strongest and significant response was observed in the Mx-1 and Vig-8 genes. The live IHN virus induced a significant response in all genes examined except TGF-β1. The control plasmid construct and the IHNV DNA vaccine marginally induced a number of genes, but the main difference between these two groups was a statistically significant induction of the Mx-1 and Vig-8 genes by the IHNV vaccine only. The gene expression profiles elicited by the live virus and the IHNV DNA vaccine differed in a number of aspects but this study confirms the clear role for a type I interferon-like response in early anti-viral defence.

Carvacrol derivatives as mushroom tyrosinase inhibitors; synthesis, kinetics mechanism and molecular docking studies.

PubMed

Ashraf, Zaman; Rafiq, Muhammad; Nadeem, Humaira; Hassan, Mubashir; Afzal, Samina; Waseem, Muhammad; Afzal, Khurram; Latip, Jalifah

2017-01-01

The present work describesthe development of highly potent mushroom tyrosinase inhibitor better than the standard kojic acid. Carvacrol derivatives 4a-f and 6a-d having substituted benzoic acid and cinnamic acidresidues were synthesized with the aim to possess potent tyrosinase inhibitory activity.The structures of the synthesized compounds were ascertained by their spectroscopic data (FTIR, 1HNMR, 13CNMR and Mass Spectroscopy).Mushroom tyrosinase inhibitory activity of synthesized compounds was determined and it was found that one of the derivative 6c possess higher activity (IC50 0.0167μM) than standard kojic acid (IC50 16.69μM). The derivatives 4c and 6b also showed good tyrosinase inhibitory activity with (IC50 16.69μM) and (IC50 16.69μM) respectively.Lineweaver-Burk and Dixon plots were used for the determination of kinetic mechanism of the compounds 4c and 6b and 6c. The kinetic analysis revealed that compounds 4c and 6b showed mixed-type inhibition while 6c is a non-competitive inhibitor having Ki values19 μM, 10 μM, and 0.05 μMrespectively. The enzyme inhibitory kinetics further showed thatcompounds 6b and 6c formed irreversible enzyme inhibitor complex while 4c bind reversibly with mushroom tyrosinase.The docking studies showed that compound 6c have maximum binding affinity against mushroom tyrosinase (PDBID: 2Y9X) with binding energy value (-7.90 kcal/mol) as compared to others.The 2-hydroxy group in compound 6c interacts with amino acid HIS85 which is present in active binding site. The wet lab results are in good agreement with the dry lab findings.Based upon our investigation we may propose that the compound 6c is promising candidate for the development of safe cosmetic agent.

Inhibition by tetanus toxin of sodium-dependent, high-affinity [3H]5-hydroxytryptamine uptake in rat synaptosomes.

PubMed

Inserte, J; Najib, A; Pelliccioni, P; Gil, C; Aguilera, J

1999-01-01

Tetanus toxin (TeTx) is a powerful clostridial neurotoxin that inhibits Ca2+-dependent neurotransmitter secretion as do the botulinum neurotoxins (BoNTs). We found that TeTx (but not BoNT/A) produced a specific time- and dose-dependent inhibition of Na+-dependent [3H]5-hydroxytryptamine (serotonin, 5-HT) uptake in rat CNS synaptosomes. This effect was found in all CNS tryptaminergic areas, being maximal in the hippocampus and occipital cortex. TeTx produced the maximum reduction in [3H]5-HT uptake after 30 min of preincubation, being significant also at lower doses (10(-12) M) or shorter incubation times (10 min). Serotonin transport inhibitors such as fenfluramine (IC50, 11.0 +/- 0.9 microM), paroxetine (IC50, 33.5 +/- 0.1 microM), and imipramine (IC50, 89.9 +/- 5.7 microM) were 3 or 4 orders of magnitude less potent than TeTx (IC50, 8.7 +/- 1.0 nM). Of the two fragments of TeTx, (the C-terminal portion of the neurotoxin heavy chain, which is responsible for the binding to the nerve tissue) was consistently more effective than the L-H(N) fragment (the light neurotoxin chain disulfide linked to the N-terminal portion of the heavy chain, which is responsible for the toxic metalloprotease action) as inhibitor of [3H]5-HT uptake in synaptosomal preparations (56 +/- 5% and 95 +/- 3% with respect to control, respectively). Antagonism of the toxin-induced [3H]5-HT uptake blockade could not be reversed by zinc chelators but did have the ability to antagonize the TeTx inhibition of basal and K+-evoked [3H]5-HT release in rat synaptosomes. The reduction in serotonin accumulation induced by TeTx could be responsible for some tetanic symptoms that have been related to the serotonergic system.

Biochemical, Cellular, and Biophysical Characterization of a Potent Inhibitor of Mutant Isocitrate Dehydrogenase IDH1*

PubMed Central

Davis, Mindy I.; Gross, Stefan; Shen, Min; Straley, Kimberly S.; Pragani, Rajan; Lea, Wendy A.; Popovici-Muller, Janeta; DeLaBarre, Byron; Artin, Erin; Thorne, Natasha; Auld, Douglas S.; Li, Zhuyin; Dang, Lenny; Boxer, Matthew B.; Simeonov, Anton

2014-01-01

Two mutant forms (R132H and R132C) of isocitrate dehydrogenase 1 (IDH1) have been associated with a number of cancers including glioblastoma and acute myeloid leukemia. These mutations confer a neomorphic activity of 2-hydroxyglutarate (2-HG) production, and 2-HG has previously been implicated as an oncometabolite. Inhibitors of mutant IDH1 can potentially be used to treat these diseases. In this study, we investigated the mechanism of action of a newly discovered inhibitor, ML309, using biochemical, cellular, and biophysical approaches. Substrate binding and product inhibition studies helped to further elucidate the IDH1 R132H catalytic cycle. This rapidly equilibrating inhibitor is active in both biochemical and cellular assays. The (+) isomer is active (IC50 = 68 nm), whereas the (−) isomer is over 400-fold less active (IC50 = 29 μm) for IDH1 R132H inhibition. IDH1 R132C was similarly inhibited by (+)-ML309. WT IDH1 was largely unaffected by (+)-ML309 (IC50 >36 μm). Kinetic analyses combined with microscale thermophoresis and surface plasmon resonance indicate that this reversible inhibitor binds to IDH1 R132H competitively with respect to α-ketoglutarate and uncompetitively with respect to NADPH. A reaction scheme for IDH1 R132H inhibition by ML309 is proposed in which ML309 binds to IDH1 R132H after formation of the IDH1 R132H NADPH complex. ML309 was also able to inhibit 2-HG production in a glioblastoma cell line (IC50 = 250 nm) and had minimal cytotoxicity. In the presence of racemic ML309, 2-HG levels drop rapidly. This drop was sustained until 48 h, at which point the compound was washed out and 2-HG levels recovered. PMID:24668804

Biochemical, cellular, and biophysical characterization of a potent inhibitor of mutant isocitrate dehydrogenase IDH1.

PubMed

Davis, Mindy I; Gross, Stefan; Shen, Min; Straley, Kimberly S; Pragani, Rajan; Lea, Wendy A; Popovici-Muller, Janeta; DeLaBarre, Byron; Artin, Erin; Thorne, Natasha; Auld, Douglas S; Li, Zhuyin; Dang, Lenny; Boxer, Matthew B; Simeonov, Anton

2014-05-16

Two mutant forms (R132H and R132C) of isocitrate dehydrogenase 1 (IDH1) have been associated with a number of cancers including glioblastoma and acute myeloid leukemia. These mutations confer a neomorphic activity of 2-hydroxyglutarate (2-HG) production, and 2-HG has previously been implicated as an oncometabolite. Inhibitors of mutant IDH1 can potentially be used to treat these diseases. In this study, we investigated the mechanism of action of a newly discovered inhibitor, ML309, using biochemical, cellular, and biophysical approaches. Substrate binding and product inhibition studies helped to further elucidate the IDH1 R132H catalytic cycle. This rapidly equilibrating inhibitor is active in both biochemical and cellular assays. The (+) isomer is active (IC50 = 68 nm), whereas the (-) isomer is over 400-fold less active (IC50 = 29 μm) for IDH1 R132H inhibition. IDH1 R132C was similarly inhibited by (+)-ML309. WT IDH1 was largely unaffected by (+)-ML309 (IC50 >36 μm). Kinetic analyses combined with microscale thermophoresis and surface plasmon resonance indicate that this reversible inhibitor binds to IDH1 R132H competitively with respect to α-ketoglutarate and uncompetitively with respect to NADPH. A reaction scheme for IDH1 R132H inhibition by ML309 is proposed in which ML309 binds to IDH1 R132H after formation of the IDH1 R132H NADPH complex. ML309 was also able to inhibit 2-HG production in a glioblastoma cell line (IC50 = 250 nm) and had minimal cytotoxicity. In the presence of racemic ML309, 2-HG levels drop rapidly. This drop was sustained until 48 h, at which point the compound was washed out and 2-HG levels recovered. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

TAN-1813, a novel Ras-farnesyltransferase inhibitor produced by Phoma sp. taxonomy, fermentation, isolation and biological activities in vitro and in vivo.

PubMed

Ishii, T; Hayashi, K; Hida, T; Yamamoto, Y; Nozaki, Y

2000-08-01

A novel Ras-farnesyltransferase inhibitor designated TAN-1813 was isolated from the culture broth of a fungus strain, FL-41510, isolated as a plant endophyte. The producer was taxonomically characterized as Phoma sp. FL-41510. TAN-1813 inhibited rat brain farnesyltransferase and geranylgeranyltransferase I activity with IC50 values of 23 microg/ml and 47/microg/ml, respectively. TAN-1813 showed mixed-type inhibition with respect to farnesylpyrophosphate and noncompetitive inhibition with respect to a K-Ras C-terminal peptide. It also inhibited the in situ farnesylation of cellular Ras proteins in a K-ras transformant (NIH3T3/K-ras) of mouse embryonic fibroblast cell line NIH3T3. TAN- 1813 inhibited the proliferation of various human cancer cells, some of which harbor activated ras alleles, with IC50 values of 15 approximately 110 ng/ml as well as that of NIH3T3 and NIH3T3/K-ras cells with IC50S of 540 and 310 ng/ml, respectively. Flow cytometric analysis indicated that TAN-1813 arrests NIH3T3/K-ras cells at both G1 and G2/M phases of the cell cycle. In addition, TAN-1813 was found to induce morphological reversion of NIH3T3/K-ras cells from the transformed phenotype. Antitumor activity of TAN-1813 against human fibrosarcoma HT-1080 and NIH3T3/K-ras tumors in nude mice was also verified.

Monoamine oxidase inhibitory activities of heterocyclic chalcones.

PubMed

Minders, Corné; Petzer, Jacobus P; Petzer, Anél; Lourens, Anna C U

2015-11-15

Studies have shown that natural and synthetic chalcones (1,3-diphenyl-2-propen-1-ones) possess monoamine oxidase (MAO) inhibition activities. Of particular importance to the present study is a report that a series of furanochalcones acts as MAO-B selective inhibitors. Since the effect of heterocyclic substitution, other than furan (and more recently thiophene, piperidine and quinoline) on the MAO inhibitory properties of the chalcone scaffold remains unexplored, the aim of this study was to synthesise and evaluate further heterocyclic chalcone analogues as inhibitors of the human MAOs. For this purpose, heterocyclic chalcone analogues that incorporate pyrrole, 5-methylthiophene, 5-chlorothiophene and 6-methoxypyridine substitution were examined. Seven of the nine synthesised compounds exhibited IC50 values <1 μM for the inhibition of MAO-B, with all compounds exhibiting higher affinities for MAO-B compared to the MAO-A isoform. The most potent MAO-B inhibitor (4h) displays an IC50 value of 0.067 μM while the most potent MAO-A inhibitor (4e) exhibits an IC50 value of 3.81 μM. It was further established that selected heterocyclic chalcones are reversible and competitive MAO inhibitors. 4h, however, may exhibit tight-binding to MAO-B, a property linked to its thiophene moiety. We conclude that high potency chalcones such as 4h represent suitable leads for the development of MAO-B inhibitors for the treatment of Parkinson's disease and possibly other neurodegenerative disorders. Copyright © 2015 Elsevier Ltd. All rights reserved.

8-Aryl- and alkyloxycaffeine analogues as inhibitors of monoamine oxidase.

PubMed

Strydom, Belinda; Bergh, Jacobus J; Petzer, Jacobus P

2011-08-01

Recently it was reported that a series of 8-benzyloxycaffeine analogues are potent reversible inhibitors of human monoamine oxidase (MAO) A and B. In an attempt to discover additional C8 oxy substituents of caffeine that lead to potent MAO inhibition, a series of related 8-aryl- and alkyloxycaffeine analogues were synthesized and their MAO-A and -B inhibition potencies were compared to those of the 8-benzyloxycaffeines. The results document that while the 8-substituted-oxycaffeine analogues inhibited both human MAO isoforms, they displayed a high degree of selectivity for MAO-B. 8-(3-Phenylpropoxy)caffeine, 8-(2-phenoxyethoxy)caffeine and 8-[(5-methylhexyl)oxy]caffeine were found to be the especially potent MAO-B inhibitors with IC(50) values ranging from 0.38 to 0.62 μM. These inhibitors are therefore 2.5-4.6 fold more potent MAO-B inhibitors than is 8-benzyloxycaffeine (IC(50) = 1.77 μM). It is also demonstrated that, analogous to 8-benzyloxycaffeine, halogen substitution on the phenyl ring of the C8 substituent significantly enhances MAO binding affinity. For example, the most potent MAO-B inhibitor of the present series is 8-[2-(4-bromophenoxy)ethoxy]caffeine with an IC(50) value of 0.166 μM. This study also reports possible binding orientations of selected oxy caffeines within the active site cavities of MAO-A and MAO-B. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Simultaneous sequencing of coding and noncoding RNA reveals a human transcriptome dominated by a small number of highly expressed noncoding genes.

PubMed

Boivin, Vincent; Deschamps-Francoeur, Gabrielle; Couture, Sonia; Nottingham, Ryan M; Bouchard-Bourelle, Philia; Lambowitz, Alan M; Scott, Michelle S; Abou-Elela, Sherif

2018-07-01

Comparing the abundance of one RNA molecule to another is crucial for understanding cellular functions but most sequencing techniques can target only specific subsets of RNA. In this study, we used a new fragmented ribodepleted TGIRT sequencing method that uses a thermostable group II intron reverse transcriptase (TGIRT) to generate a portrait of the human transcriptome depicting the quantitative relationship of all classes of nonribosomal RNA longer than 60 nt. Comparison between different sequencing methods indicated that FRT is more accurate in ranking both mRNA and noncoding RNA than viral reverse transcriptase-based sequencing methods, even those that specifically target these species. Measurements of RNA abundance in different cell lines using this method correlate with biochemical estimates, confirming tRNA as the most abundant nonribosomal RNA biotype. However, the single most abundant transcript is 7SL RNA, a component of the signal recognition particle. S tructured n on c oding RNAs (sncRNAs) associated with the same biological process are expressed at similar levels, with the exception of RNAs with multiple functions like U1 snRNA. In general, sncRNAs forming RNPs are hundreds to thousands of times more abundant than their mRNA counterparts. Surprisingly, only 50 sncRNA genes produce half of the non-rRNA transcripts detected in two different cell lines. Together the results indicate that the human transcriptome is dominated by a small number of highly expressed sncRNAs specializing in functions related to translation and splicing. © 2018 Boivin et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

Adenosine 3′,5′-cyclic monophosphate (cAMP)-dependent phosphoregulation of mitochondrial complex I is inhibited by nucleoside reverse transcriptase inhibitors

PubMed Central

Lund, Kaleb C.; Wallace, Kendall B.

2008-01-01

Nucleoside analog reverse transcriptase inhibitors (NRTI) are known to directly inhibit mitochondrial complex I activity as well as various mitochondrial kinases. Recent observations that complex I activity and superoxide production are modulated through cAMP-dependent phosphorylation suggests a mechanism through which NRTIs may affect mitochondrial respiration via kinase-dependent protein phosphorylation. In the current study we examine the potential for NRTIs to inhibit the cAMP-dependent phosphorylation of complex I and the associated NADH:CoQ oxidoreductase activities and rates of superoxide production using HepG2 cells. Phosphoprotein staining of immunocaptured complex I revealed that 3′-azido-3′-deoxythymidine (AZT; 10 and 50 μM), AZT monophosphate (150 μM), and 2′,3′-dideoxycytidine (ddC; 1μM) prevented the phosphorylation of the NDUFB11 subunit of complex I. This was associated with a decrease in complex I activity with AZT and AZT monophosphate only. In the presence of succinate, superoxide production was increased with 2′,3′-dideoxyinosine (ddI; 10 μM) and ddC (1 μM). In the presence of succinate + cAMP AZT showed an inverse dose-dependent effect on superoxide production. None of the NRTIs examined inhibit PKA activity suggesting that the observed effects are due to a direct interaction with complex I. These data demonstrate a direct effect of NRTIs on cAMP-dependent regulation of mitochondrial bioenergetics independent of DNA polymerase-γ activity; in the case of AZT these observations may provide a mechanism for the observed long-term toxicity with this drug. PMID:17904600

Sensitivity and specificity of a real-time reverse transcriptase polymerase chain reaction detecting feline coronavirus mutations in effusion and serum/plasma of cats to diagnose feline infectious peritonitis.

PubMed

Felten, Sandra; Leutenegger, Christian M; Balzer, Hans-Joerg; Pantchev, Nikola; Matiasek, Kaspar; Wess, Gerhard; Egberink, Herman; Hartmann, Katrin

2017-08-02

Feline coronavirus (FCoV) exists as two pathotypes, and FCoV spike gene mutations are considered responsible for the pathotypic switch in feline infectious peritonitis (FIP) pathogenesis. The aim of this study was to evaluate sensitivity and specificity of a real-time reverse transcriptase polymerase chain reaction (RT-PCR) specifically designed to detect FCoV spike gene mutations at two nucleotide positions. It was hypothesized that this test would correctly discriminate feline infectious peritonitis virus (FIPV) and feline enteric coronavirus (FECV). The study included 63 cats with signs consistent with FIP. FIP was confirmed in 38 cats. Twenty-five control cats were definitively diagnosed with a disease other than FIP. Effusion and/or serum/plasma samples were examined by real-time RT-PCR targeting the two FCoV spike gene fusion peptide mutations M1058 L and S1060A using an allelic discrimination approach. Sensitivity, specificity, negative and positive predictive values including 95% confidence intervals (95% CI) were calculated. FIPV was detected in the effusion of 25/59 cats, one of them being a control cat with chronic kidney disease. A mixed population of FIPV/FECV was detected in the effusion of 2/59 cats; all of them had FIP. RT-PCR was negative or the pathotype could not be determined in 34/59 effusion samples. In effusion, sensitivity was 68.6% (95% CI 50.7-83.2), specificity was 95.8% (95% CI 78.9-99.9). No serum/plasma samples were positive for FIPV. Although specificity of the test in effusions was high, one false positive result occurred. The use of serum/plasma cannot be recommended due to a low viral load in blood.

Impact of Human Immunodeficiency Virus Type 1 Minority Variants on the Virus Response to a Rilpivirine-Based First-line Regimen.

PubMed

Raymond, Stéphanie; Nicot, Florence; Pallier, Coralie; Bellecave, Pantxika; Maillard, Anne; Trabaud, Mary Anne; Morand-Joubert, Laurence; Rodallec, Audrey; Amiel, Corinne; Mourez, Thomas; Bocket, Laurence; Beby-Defaux, Agnès; Bouvier-Alias, Magali; Lambert-Niclot, Sidonie; Charpentier, Charlotte; Malve, Brice; Mirand, Audrey; Dina, Julia; Le Guillou-Guillemette, Hélène; Marque-Juillet, Stéphanie; Signori-Schmuck, Anne; Barin, Francis; Si-Mohamed, Ali; Avettand Fenoel, Véronique; Roussel, Catherine; Calvez, Vincent; Saune, Karine; Marcelin, Anne Geneviève; Rodriguez, Christophe; Descamps, Diane; Izopet, Jacques

2018-05-02

Minority resistant variants of human immunodeficiency virus type 1 (HIV-1) could influence the virological response to treatment based on nonnucleoside reverse transcriptase inhibitors (NNRTIs). Data on minority rilpivirine-resistant variants are scarce. This study used next-generation sequencing (NGS) to identify patients harboring minority resistant variants to nucleos(t)ide reverse transcriptase inhibitors and NNRTIs and to assess their influence on the virological response (VR). All the subjects, 541 HIV-1-infected patients started a first-line regimen containing rilpivirine. VR was defined as a HIV-1 RNA load <50 copies/mL at month 6 with continued suppression at month 12. NGS was performed at baseline (retrospectively) on the 454 GS-FLX platform (Roche). NGS revealed resistance-associated mutations accounting for 1% to <5% of variants in 17.2% of samples, for 5%-20% in 5.7% of samples, and for >20% in 29% of samples. We identified 43 (8.8%) and 36 (7.4%) patients who harbored rilpivirine-resistant variants with a 1% sensitivity threshold according to the French National Agency for Research on AIDS and Viral Hepatitis and Stanford algorithms, respectively. The VR was 96.9% at month 12. Detection of minority rilpivirine resistant variants was not associated with virological failure (VF). Multivariate analysis indicated that VF at month 12 was associated with a CD4 count <250 cells/µL at baseline, a slower decrease in viral load at month 3, and rilpivirine resistance at baseline using the Stanford algorithm with a 20% threshold. Minority resistant variants had no impact on the VR of treatment-naive patients to a rilpivirine-based regimen.

HIV Salvage Therapy Does Not Require Nucleoside Reverse Transcriptase Inhibitors: A Randomized, Controlled Trial.

PubMed

Tashima, Karen T; Smeaton, Laura M; Fichtenbaum, Carl J; Andrade, Adriana; Eron, Joseph J; Gandhi, Rajesh T; Johnson, Victoria A; Klingman, Karin L; Ritz, Justin; Hodder, Sally; Santana, Jorge L; Wilkin, Timothy; Haubrich, Richard H

2015-12-15

Nucleoside reverse transcriptase inhibitors (NRTIs) are often included in antiretroviral regimens in treatment-experienced patients in the absence of data from randomized trials. To compare treatment success between participants who omit versus those who add NRTIs to an optimized antiretroviral regimen of 3 or more agents. Multicenter, randomized, controlled trial. (ClinicalTrials.gov: NCT00537394). Outpatient HIV clinics. Treatment-experienced patients with HIV infection and viral resistance. Open-label optimized regimens (not including NRTIs) were selected on the basis of treatment history and susceptibility testing. Participants were randomly assigned to omit or add NRTIs. The primary efficacy outcome was regimen failure through 48 weeks using a noninferiority margin of 15%. The primary safety outcome was time to initial episode of a severe sign, symptom, or laboratory abnormality before discontinuation of NRTI assignment. 360 participants were randomly assigned, and 93% completed a 48-week visit. The cumulative probability of regimen failure was 29.8% in the omit-NRTIs group versus 25.9% in the add-NRTIs group (difference, 3.2 percentage points [95% CI, -6.1 to 12.5 percentage points]). No significant between-group differences were found in the primary safety end points or the proportion of participants with HIV RNA level less than 50 copies/mL. No deaths occurred in the omit-NRTIs group compared with 7 deaths in the add-NRTIs group. Unblinded study design, and the study may not be applicable to resource-poor settings. Treatment-experienced patients with HIV infection starting a new optimized regimen can safely omit NRTIs without compromising virologic efficacy. Omitting NRTIs will reduce pill burden, cost, and toxicity in this patient population. National Institute of Allergy and Infectious Diseases, Boehringer Ingelheim, Janssen, Merck, ViiV Healthcare, Roche, and Monogram Biosciences (LabCorp).

HIV salvage therapy does not require nucleoside reverse transcriptase inhibitors: a randomized trial

PubMed Central

Tashima, Karen T; Smeaton, Laura M; Fichtenbaum, Carl J; Andrade, Adriana; Eron, Joseph J; Gandhi, Rajesh T; Johnson, Victoria A; Klingman, Karin L; Ritz, Justin; Hodder, Sally; Santana, Jorge L; Wilkin, Timothy; Haubrich, Richard H

2015-01-01

Background Nucleoside reverse transcriptase inhibitors (NRTIs) are often included in antiretroviral (ARV) regimens in treatment-experienced patients in the absence of data from randomized trials. Objective To compare treatment success between participants who omit versus Add NRTIs to an optimized ARV regimen of three or more agents. Design Multisite, randomized, controlled trial. Setting Outpatient HIV clinics. Participants HIV-infected patients with three-class ARV experience and/or viral resistance. Intervention Open-label optimized regimens (not including NRTIs) were selected based upon treatment history and susceptibility testing. Participants were randomized to Omit or Add NRTIs. Measurements The primary efficacy outcome was regimen failure through week 48, using a non-inferiority margin of 15%. The primary safety outcome was time to initial episode of severe sign/symptom or laboratory abnormality prior to discontinuation of NRTI assignment. Results 360 participants were randomized and 93% completed a week 48 visit. The cumulative probability of regimen failure was 29.8% in the Omit NRTI arm versus 25.9% in the Add NRTI arm (difference= 3.2%: 95% CI, −6.1 to 12.5). There were no significant differences in the primary safety endpoints or the proportion of participants with HIV RNA <50 copies/mL between arms. No deaths occurred in the Omit NRTIs arm, compared with 7 deaths in the Add NRTIs arm. Limitations Non-blinded study design and may not be applicable to resource poor settings. Conclusion HIV-infected treatment-experienced patients starting a new optimized regimen can safely omit NRTIs without compromising virologic efficacy. Omitting NRTIs will reduce pill burden, cost, and toxicity in this patient population. PMID:26595748

Synthesis of heteroaromatic tropeines and heterogeneous binding to glycine receptors.

PubMed

Maksay, Gábor; Vincze, Zoltán; Nemes, Péter

2009-10-01

Heteroaromatic carboxylic esters of (nor)tropine were synthesized. Tropine esters displaced [(3)H]strychnine binding to glycine receptors of rat spinal cord with low Hill slopes. Two-site displacement resulted in nanomolar IC(50,1) and micromolar IC(50,2) values, and IC(50,2)/IC(50,1) ratios up to 615 depending on the heteroaromatic rings and N-methyl substitution. Nortropeines displayed high affinity and low heterogeneity. IC(50,1) and IC(50,2) values of tropeines did not correlate suggesting different binding modes/sites. Glycine potentiated only the nanomolar displacement reflecting positive allosteric interactions and potentiation of ionophore function. Affinities of three (nor)tropeines were different for glycine receptors but identical for 5-HT(3) receptors.

Improved Potency of Indole-Based NorA Efflux Pump Inhibitors: From Serendipity toward Rational Design and Development.

PubMed

Buonerba, Federica; Lepri, Susan; Goracci, Laura; Schindler, Bryan D; Seo, Susan M; Kaatz, Glenn W; Cruciani, Gabriele

2017-01-12

The NorA efflux pump is a potential drug target for reversal of resistance to selected antibacterial agents, and recently we described indole-based inhibitor candidates. Herein we report a second class of inhibitors derived from them but with significant differences in shape and size. In particular, compounds 13 and 14 are very potent inhibitors in that they demonstrated the lowest IC 50 values (2 μM) ever observed among all indole-based compounds we have evaluated.

Problem-Solving Test: Catalytic Activities of a Human Nuclear Enzyme

ERIC Educational Resources Information Center

Szeberenyi, Jozsef

2011-01-01

Terms to be familiar with before you start to solve the test: ion exchange chromatography, polynucleotides, oligonucleotides, radioactive labeling, template, primer, DNA polymerase, reverse transcriptase, helicase, nucleoside triphosphates, nucleoside diphosphates, nucleoside monophosphates, nucleosides, 5'-end and 3'-end, bacteriophage,…

Literature Reference for Influenza H5N1 (Emerging Infectious Diseases. 2005. 11(8): 1303–1305)

EPA Pesticide Factsheets

Procedures are described for analysis of clinical samples and may be adapted for assessment of solid, particulate, aerosol, liquid and water samples. This is a two-step, real-time reverse transcriptase-PCR multiplex assay.

Secondary structure model of the RNA recognized by the reverse transcriptase from the R2 retrotransposable element.

PubMed Central

Mathews, D H; Banerjee, A R; Luan, D D; Eickbush, T H; Turner, D H

1997-01-01

RNA transcripts corresponding to the 250-nt 3' untranslated region of the R2 non-LTR retrotransposable element are recognized by the R2 reverse transcriptase and are sufficient to serve as templates in the target DNA-primed reverse transcription (TPRT) reaction. The R2 protein encoded by the Bombyx mori R2 can recognize this region from both the B. mori and Drosophila melanogaster R2 elements even though these regions show little nucleotide sequence identity. A model for the RNA secondary structure of the 3' untranslated region of the D. melanogaster R2 retrotransposon was developed by sequence comparison of 10 species aided by free energy minimization. Chemical modification experiments are consistent with this prediction. A secondary structure model for the 3' untranslated region of R2 RNA from the R2 element from B. mori was obtained by a combination of chemical modification data and free energy minimization. These two secondary structure models, found independently, share several common sites. This study shows the utility of combining free energy minimization, sequence comparison, and chemical modification to model an RNA secondary structure. PMID:8990394

Design and Synthesis of Human ABCB1 (P-Glycoprotein) Inhibitors by Peptide Coupling of Diverse Chemical Scaffolds on Carboxyl and Amino Termini of (S)-Valine-Derived Thiazole Amino Acid

PubMed Central

2015-01-01

P-glycoprotein (P-gp) serves as a therapeutic target for the development of multidrug resistance reversal agents. In this study, we synthesized 21 novel compounds by peptide coupling at corresponding carboxyl and amino termini of (S)-valine-based bis-thiazole and monothiazole derivatives with diverse chemical scaffolds. Using calcein-AM efflux assay, we identified compound 28 (IC50 = 1.0 μM) carrying 3,4,5-trimethoxybenzoyl and 2-aminobenzophenone groups, respectively, at the amino and carboxyl termini of the monothiazole zwitter-ion. Compound 28 inhibited the photolabeling of P-gp with [125I]-iodoarylazidoprazosin with IC50 = 0.75 μM and stimulated the basal ATP hydrolysis of P-gp in a concentration-dependent manner (EC50 ATPase = 0.027 μM). Compound 28 at 3 μM reduced resistance in cytotoxicity assay to paclitaxel in P-gp-expressing SW620/Ad300 and HEK/ABCB1 cell lines. Biochemical and docking studies showed site-1 to be the preferable binding site for 28 within the drug-binding pocket of human P-gp. PMID:24773054

Impact of human immunodeficiency virus type 1 reverse transcriptase inhibitor drug resistance mutation interactions on phenotypic susceptibility.

PubMed

Trivedi, Vinod; Von Lindern, Jana; Montes-Walters, Miguel; Rojo, Daniel R; Shell, Elisabeth J; Parkin, Neil; O'Brien, William A; Ferguson, Monique R

2008-10-01

The role specific reverse transcriptase (RT) drug resistance mutations play in influencing phenotypic susceptibility to RT inhibitors in virus strains with complex resistance interaction patterns was assessed using recombinant viruses that consisted of RT-PCR-amplified pol fragments derived from plasma HIV-1 RNA from two treatment-experienced patients. Specific modifications of key RT amino acids were performed by site-directed mutagenesis. A panel of viruses with defined genotypic resistance mutations was assessed for phenotypic drug resistance. Introduction of M184V into several different clones expressing various RT resistance mutations uniformly decreased susceptibility to abacavir, lamivudine, and didanosine, and increased susceptibility to zidovudine, stavudine, and tenofovir; replication capacity was decreased. The L74V mutation had similar but slightly different effects, contributing to decreased susceptibility to abacavir, lamivudine, and didanosine and increased susceptibility to zidovudine and tenofovir, but in contrast to M184V, L74V contributed to decreased susceptibility to stavudine. In virus strains with the nonnucleoside reverse transcriptase inhibitor (NNRTI) mutations K101E and G190S, the L74V mutation increased replication capacity, consistent with published observations, but replication capacity was decreased in strains without NNRTI resistance mutations. K101E and G190S together tend to decrease susceptibility to all nucleoside RT inhibitors, but the K103N mutation had little effect on nucleoside RT inhibitor susceptibility. Mutational interactions can have a substantial impact on drug resistance phenotype and replication capacity, and this has been exploited in clinical practice with the development of fixed-dose combination pills. However, we are the first to report these mutational interactions using molecularly cloned recombinant strains derived from viruses that occur naturally in HIV-infected individuals.

Transmitted drug resistance is still low in newly diagnosed human immunodeficiency virus type 1 CRF06_cpx-infected patients in Estonia in 2010.

PubMed

Avi, Radko; Huik, Kristi; Pauskar, Merit; Ustina, Valentina; Karki, Tõnis; Kallas, Eveli; Jõgeda, Ene-Ly; Krispin, Tõnu; Lutsar, Irja

2014-03-01

The presence of transmitted drug resistance (TDR) in treatment-naive HIV-1-positive subjects is of concern, especially in the countries of the former Soviet Union in which the number of subjects exposed to antiretrovirals (ARV) has exponentially increased during the past decade. We assessed the rate of TDR among newly diagnosed subjects in Estonia in 2010 and compared it to that in 2008. The study included 325 subjects (87% of all subjects tested HIV positive from January 1 to December 31, 2010). Of the 244 sequenced viral genomic RNA in the reverse transcriptase (RT) region 214 were CRF06_cpx, nine were subtype A1, three (one each) were subtype B and subtype C, CRF02_AG, and CRF03_AB; 15 viruses remained unclassified as putative recombinant forms between CRF06_cpx and subtype A1. HIV-1 TDR mutations in 2010 and 2008 (n=145) occurred at similar frequency in 4.5% (95% CI 2.45; 7.98) and 5.5% (95% CI 1.8; 9.24) of the patients, respectively. In 2010, 2.5% (6/244) of the sequences harbored nonnucleoside reverse transcriptase inhibitor (NNRTI) (K103N and K101E), 1.6% (4/244) nucleoside reverse transcriptase inhibitor (NRTI) (M41L, M184I, and K219E), and 0.4% (1/244) protease inhibitor (PI) (V82A) mutations. Our findings indicate that in spite of the increased consumption of ARVs the rate of TDR in Estonia has remained unchanged over the past 3 years. Similar stabilizing or even decreasing trends have been described in Western Europe and North America albeit at higher levels and in different socioeconomic backgrounds.

Impact of Human Immunodeficiency Virus Type 1 Reverse Transcriptase Inhibitor Drug Resistance Mutation Interactions on Phenotypic Susceptibility

PubMed Central

Trivedi, Vinod; Von Lindern, Jana; Montes-Walters, Miguel; Rojo, Daniel R.; Shell, Elisabeth J.; Parkin, Neil; O'Brien, William A.

2008-01-01

Abstract The role specific reverse transcriptase (RT) drug resistance mutations play in influencing phenotypic susceptibility to RT inhibitors in virus strains with complex resistance interaction patterns was assessed using recombinant viruses that consisted of RT-PCR-amplified pol fragments derived from plasma HIV-1 RNA from two treatment-experienced patients. Specific modifications of key RT amino acids were performed by site-directed mutagenesis. A panel of viruses with defined genotypic resistance mutations was assessed for phenotypic drug resistance. Introduction of M184V into several different clones expressing various RT resistance mutations uniformly decreased susceptibility to abacavir, lamivudine, and didanosine, and increased susceptibility to zidovudine, stavudine, and tenofovir; replication capacity was decreased. The L74V mutation had similar but slightly different effects, contributing to decreased susceptibility to abacavir, lamivudine, and didanosine and increased susceptibility to zidovudine and tenofovir, but in contrast to M184V, L74V contributed to decreased susceptibility to stavudine. In virus strains with the nonnucleoside reverse transcriptase inhibitor (NNRTI) mutations K101E and G190S, the L74V mutation increased replication capacity, consistent with published observations, but replication capacity was decreased in strains without NNRTI resistance mutations. K101E and G190S together tend to decrease susceptibility to all nucleoside RT inhibitors, but the K103N mutation had little effect on nucleoside RT inhibitor susceptibility. Mutational interactions can have a substantial impact on drug resistance phenotype and replication capacity, and this has been exploited in clinical practice with the development of fixed-dose combination pills. However, we are the first to report these mutational interactions using molecularly cloned recombinant strains derived from viruses that occur naturally in HIV-infected individuals. PMID:18844463

Isolation of a candidate human telomerase catalytic subunit gene, which reveals complex splicing patterns in different cell types.

PubMed

Kilian, A; Bowtell, D D; Abud, H E; Hime, G R; Venter, D J; Keese, P K; Duncan, E L; Reddel, R R; Jefferson, R A

1997-11-01

Telomerase is a multicomponent reverse transcriptase enzyme that adds DNA repeats to the ends of chromosomes using its RNA component as a template for synthesis. Telomerase activity is detected in the germline as well as the majority of tumors and immortal cell lines, and at low levels in several types of normal cells. We have cloned a human gene homologous to a protein from Saccharomyces cerevisiae and Euplotes aediculatus that has reverse transcriptase motifs and is thought to be the catalytic subunit of telomerase in those species. This gene is present in the human genome as a single copy sequence with a dominant transcript of approximately 4 kb in a human colon cancer cell line, LIM1215. The cDNA sequence was determined using clones from a LIM1215 cDNA library and by RT-PCR, cRACE and 3'RACE on mRNA from the same source. We show that the gene is expressed in several normal tissues, telomerase-positive post-crisis (immortal) cell lines and various tumors but is not expressed in the majority of normal tissues analyzed, pre-crisis (non-immortal) cells and telomerase-negative immortal (ALT) cell lines. Multiple products were identified by RT-PCR using primers within the reverse transcriptase domain. Sequencing of these products suggests that they arise by alternative splicing. Strikingly, various tumors, cell lines and even normal tissues (colonic crypt and testis) showed considerable differences in the splicing patterns. Alternative splicing of the telomerase catalytic subunit transcript may be important for the regulation of telomerase activity and may give rise to proteins with different biochemical functions.

The site-specific ribosomal insertion element type II of Bombyx mori (R2Bm) contains the coding sequence for a reverse transcriptase-like enzyme.

PubMed Central

Burke, W D; Calalang, C C; Eickbush, T H

1987-01-01

Two classes of DNA elements interrupt a fraction of the rRNA repeats of Bombyx mori. We have analyzed by genomic blotting and sequence analysis one class of these elements which we have named R2. These elements occupy approximately 9% of the rDNA units of B. mori and appear to be homologous to the type II rDNA insertions detected in Drosophila melanogaster. Approximately 25 copies of R2 exist within the B. mori genome, of which at least 20 are located at a precise location within otherwise typical rDNA units. Nucleotide sequence analysis has revealed that the 4.2-kilobase-pair R2 element has a single large open reading frame, occupying over 82% of the total length of the element. The central region of this 1,151-amino-acid open reading frame shows homology to the reverse transcriptase enzymes found in retroviruses and certain transposable elements. Amino acid homology of this region is highest to the mobile line 1 elements of mammals, followed by the mitochondrial type II introns of fungi, and the pol gene of retroviruses. Less homology exists with transposable elements of D. melanogaster and Saccharomyces cerevisiae. Two additional regions of sequence homology between L1 and R2 elements were also found outside the reverse transcriptase region. We suggest that the R2 elements are retrotransposons that are site specific in their insertion into the genome. Such mobility would enable these elements to occupy a small fraction of the rDNA units of B. mori despite their continual elimination from the rDNA locus by sequence turnover. Images PMID:2439905

Giant Reverse Transcriptase-Encoding Transposable Elements at Telomeres.

PubMed

Arkhipova, Irina R; Yushenova, Irina A; Rodriguez, Fernando

2017-09-01

Transposable elements are omnipresent in eukaryotic genomes and have a profound impact on chromosome structure, function and evolution. Their structural and functional diversity is thought to be reasonably well-understood, especially in retroelements, which transpose via an RNA intermediate copied into cDNA by the element-encoded reverse transcriptase, and are characterized by a compact structure. Here, we report a novel type of expandable eukaryotic retroelements, which we call Terminons. These elements can attach to G-rich telomeric repeat overhangs at the chromosome ends, in a process apparently facilitated by complementary C-rich repeats at the 3'-end of the RNA template immediately adjacent to a hammerhead ribozyme motif. Terminon units, which can exceed 40 kb in length, display an unusually complex and diverse structure, and can form very long chains, with host genes often captured between units. As the principal polymerizing component, Terminons contain Athena reverse transcriptases previously described in bdelloid rotifers and belonging to the enigmatic group of Penelope-like elements, but can additionally accumulate multiple cooriented ORFs, including DEDDy 3'-exonucleases, GDSL esterases/lipases, GIY-YIG-like endonucleases, rolling-circle replication initiator (Rep) proteins, and putatively structural ORFs with coiled-coil motifs and transmembrane domains. The extraordinary length and complexity of Terminons and the high degree of interfamily variability in their ORF content challenge the current views on the structural organization of eukaryotic retroelements, and highlight their possible connections with the viral world and the implications for the elevated frequency of gene transfer. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Expression of Connexin 43 in Synovial Tissue of Patients With Rheumatoid Arthritis

PubMed Central

MATSUKI, Tomohiro; TSUCHIDA, Shinji; TERAUCHI, Ryu; ODA, Ryo; FUJIWARA, Hiroyoshi; MAZDA, Osam; KUBO, Toshikazu

2016-01-01

Objectives This study aims to identify the distribution and expression level of connexin 43 (Cx43) in synovial tissue in patients with rheumatoid arthritis (RA). Patients and methods The expression of Cx43 in synovial tissue from eight patients with RA (2 males, 6 females; mean age 59.5±2.7 years; range 52 to 71 years), five patients with osteoarthritis (2 males, 3 females; mean age 68.4±2.7 years; range 61 to 81 years), and one normal female subject (mean age 61 year) was analyzed by quantitative reverse transcriptase polymerase chain reaction and immunohistochemistry of tissue sections. Induction of Cx43 following stimulation of human RA synovial fibroblasts with tumor necrosis factor-alpha (TNF-a) cultures was examined by quantitative reverse transcriptase polymerase chain reaction. The effect of small interfering ribonucleic acid targeting Cx43 (siCx43) on the expression of TNF-a and interleukin-6 was examined using quantitative reverse transcriptase polymerase chain reaction and enzyme-linked immunosorbent assays. Results Connexin 43 was highly expressed in RA synovial tissue, which also expressed TNF-a, but was expressed lower in osteoarthritis and normal synovial tissue. Expression of Cx43 was markedly up-regulated in RA synovial fibroblasts after stimulation with TNF-a. The over-expression of pro- inflammatory cytokines was suppressed by transfection of siCx43. Conclusion This study shows that Cx43 is expressed in RA synovial tissue and that its expression is induced by stimulation with TNF-a. The expression of the pro-inflammatory cytokines was inhibited by transfection of siCx43. Cx43 may be a novel marker of inflammation in RA synovial tissue. PMID:29900991

Antioxidants inhibit nuclear export of telomerase reverse transcriptase and delay replicative senescence of endothelial cells.

PubMed

Haendeler, Judith; Hoffmann, Jörg; Diehl, J Florian; Vasa, Mariuca; Spyridopoulos, Ioakim; Zeiher, Andreas M; Dimmeler, Stefanie

2004-04-02

Aging is associated with a rise in intracellular reactive oxygen species (ROS) and a loss of telomerase reverse transcriptase activity. Incubation with H2O2 induced the nuclear export of telomerase reverse transcriptase (TERT) into the cytosol in a Src-family kinase-dependent manner. Therefore, we investigated the hypothesis that age-related increase in reactive oxygen species (ROS) may induce the nuclear export of TERT and contribute to endothelial cell senescence. Continuous cultivation of endothelial cells resulted in an increased endogenous formation of ROS starting after 29 population doublings (PDL). This increase was accompanied by mitochondrial DNA damage and preceded the onset of replicative senescence at PDL 37. Along with the enhanced formation of ROS, we detected an export of nuclear TERT protein from the nucleus into the cytoplasm and an activation of the Src-kinase. Moreover, the induction of premature senescence by low concentrations of H2O2 was completely blocked with the Src-family kinase inhibitor PP2, suggesting a crucial role for Src-family kinases in the induction of endothelial cell aging. Incubation with the antioxidant N-acetylcysteine, from PDL 26, reduced the intracellular ROS formation and prevented mitochondrial DNA damage. Likewise, nuclear export of TERT protein, loss in the overall TERT activity, and the onset of replicative senescence were delayed by incubation with N-acetylcysteine. Low doses of the statin, atorvastatin (0.1 micromol/L), had also effects similar to those of N-acetylcysteine. We conclude that both antioxidants and statins can delay the onset of replicative senescence by counteracting the increased ROS production linked to aging of endothelial cells.

Potent NLRP3 Inflammasome Activation by the HIV Reverse Transcriptase Inhibitor Abacavir.

PubMed

Toksoy, Atiye; Sennefelder, Helga; Adam, Christian; Hofmann, Sonja; Trautmann, Axel; Goebeler, Matthias; Schmidt, Marc

2017-02-17

There is experimental and clinical evidence that some exanthematous allergic drug hypersensitivity reactions are mediated by drug-specific T cells. We hypothesized that the capacity of certain drugs to directly stimulate the innate immune system may contribute to generate drug-specific T cells. Here we analyzed whether abacavir, an HIV-1 reverse transcriptase inhibitor often inducing severe delayed-type drug hypersensitivity, can trigger innate immune activation that may contribute to its allergic potential. We show that abacavir fails to generate direct innate immune activation in human monocytes but potently triggers IL-1β release upon pro-inflammatory priming with phorbol ester or Toll-like receptor stimulation. IL-1β processing and secretion were sensitive to Caspase-1 inhibition, NLRP3 knockdown, and K + efflux inhibition and were not observed with other non-allergenic nucleoside reverse transcriptase inhibitors, identifying abacavir as a specific inflammasome activator. It further correlated with dose-dependent mitochondrial reactive oxygen species production and cytotoxicity, indicating that inflammasome activation resulted from mitochondrial damage. However, both NLRP3 depletion and inhibition of K + efflux mitigated abacavir-induced mitochondrial reactive oxygen species production and cytotoxicity, suggesting that these processes were secondary to NLRP3 activation. Instead, depletion of cardiolipin synthase 1 abolished abacavir-induced IL-1β secretion, suggesting that mitochondrial cardiolipin release may trigger abacavir-induced inflammasome activation. Our data identify abacavir as a novel inflammasome-stimulating drug allergen. They implicate a potential contribution of innate immune activation to medication-induced delayed-type hypersensitivity, which may stimulate new concepts for treatment and prevention of drug allergies. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Comparative analysis of drug resistance mutations in the human immunodeficiency virus reverse transcriptase gene in patients who are non-responsive, responsive and naive to antiretroviral therapy.

PubMed

Misbah, Mohammad; Roy, Gaurav; Shahid, Mudassar; Nag, Nalin; Kumar, Suresh; Husain, Mohammad

2016-05-01

Drug resistance mutations in the Pol gene of human immunodeficiency virus 1 (HIV-1) are one of the critical factors associated with antiretroviral therapy (ART) failure in HIV-1 patients. The issue of resistance to reverse transcriptase inhibitors (RTIs) in HIV infection has not been adequately addressed in the Indian subcontinent. We compared HIV-1 reverse transcriptase (RT) gene sequences to identify mutations present in HIV-1 patients who were ART non-responders, ART responders and drug naive. Genotypic drug resistance testing was performed by sequencing a 655-bp region of the RT gene from 102 HIV-1 patients, consisting of 30 ART-non-responding, 35 ART-responding and 37 drug-naive patients. The Stanford HIV Resistance Database (HIVDBv 6.2), IAS-USA mutation list, ANRS_09/2012 algorithm, and Rega v8.02 algorithm were used to interpret the pattern of drug resistance. The majority of the sequences (96 %) belonged to subtype C, and a few of them (3.9 %) to subtype A1. The frequency of drug resistance mutations observed in ART-non-responding, ART-responding and drug-naive patients was 40.1 %, 10.7 % and 20.58 %, respectively. It was observed that in non-responders, multiple mutations were present in the same patient, while in responders, a single mutation was found. Some of the drug-naive patients had more than one mutation. Thymidine analogue mutations (TAMs), however, were found in non-responders and naive patients but not in responders. Although drug resistance mutations were widely distributed among ART non-responders, the presence of resistance mutations in the viruses of drug-naive patients poses a big concern in the absence of a genotyping resistance test.

RNA–protein binding interface in the telomerase ribonucleoprotein

PubMed Central

Bley, Christopher J.; Qi, Xiaodong; Rand, Dustin P.; Borges, Chad R.; Nelson, Randall W.; Chen, Julian J.-L.

2011-01-01

Telomerase is a specialized reverse transcriptase containing an intrinsic telomerase RNA (TR) which provides the template for telomeric DNA synthesis. Distinct from conventional reverse transcriptases, telomerase has evolved a unique TR-binding domain (TRBD) in the catalytic telomerase reverse transcriptase (TERT) protein, integral for ribonucleoprotein assembly. Two structural elements in the vertebrate TR, the pseudoknot and CR4/5, bind TERT independently and are essential for telomerase enzymatic activity. However, the details of the TR–TERT interaction have remained elusive. In this study, we employed a photoaffinity cross-linking approach to map the CR4/5-TRBD RNA–protein binding interface by identifying RNA and protein residues in close proximity. Photoreactive 5-iodouridines were incorporated into the medaka CR4/5 RNA fragment and UV cross-linked to the medaka TRBD protein fragment. The cross-linking RNA residues were identified by alkaline partial hydrolysis and cross-linked protein residues were identified by mass spectrometry. Three CR4/5 RNA residues (U182, U187, and U205) were found cross-linking to TRBD amino acids Tyr503, Phe355, and Trp477, respectively. This CR4/5 binding pocket is distinct and separate from the previously proposed T pocket in the Tetrahymena TRBD. Based on homologous structural models, our cross-linking data position the essential loop L6.1 adjacent to the TERT C-terminal extension domain. We thus propose that stem-loop 6.1 facilitates proper TERT folding by interacting with both TRBD and C-terminal extension. Revealing the telomerase CR4/5-TRBD binding interface with single-residue resolution provides important insights into telomerase ribonucleoprotein architecture and the function of the essential CR4/5 domain. PMID:22123986

Drug Susceptibility and Resistance Mutations After First-Line Failure in Resource Limited Settings

PubMed Central

Wallis, Carole L.; Aga, Evgenia; Ribaudo, Heather; Saravanan, Shanmugam; Norton, Michael; Stevens, Wendy; Kumarasamy, Nagalingeswaran; Bartlett, John; Katzenstein, David

2014-01-01

Background. The development of drug resistance to nucleoside reverse transcriptase inhibitors (NRTIs) and nonnucleoside reverse transcriptase inhibitors (NNRTIs) has been associated with baseline human immunodeficiency virus (HIV)-1 RNA level (VL), CD4 cell counts (CD4), subtype, and treatment failure duration. This study describes drug resistance and levels of susceptibility after first-line virologic failure in individuals from Thailand, South Africa, India, Malawi, Tanzania. Methods. CD4 and VL were captured at AIDs Clinical Trial Group (ACTG) A5230 study entry, a study of lopinavir/ritonavir (LPV/r) monotherapy after first-line virologic failure on an NNRTI regimen. HIV drug-resistance mutation associations with subtype, site, study entry VL, and CD4 were evaluated using Fisher exact and Kruskall–Wallis tests. Results. Of the 207 individuals who were screened for A5230, sequence data were available for 148 individuals. Subtypes observed: subtype C (n = 97, 66%) AE (n = 27, 18%), A1 (n = 12, 8%), and D (n = 10, 7%). Of the 148 individuals, 93% (n = 138) and 96% (n = 142) had at least 1 reverse transcriptase (RT) mutation associated with NRTI and NNRTI resistance, respectively. The number of NRTI mutations was significantly associated with a higher study screening VL and lower study screening CD4 (P < .001). Differences in drug-resistance patterns in both NRTI and NNRTI were observed by site. Conclusions. The degree of NNRTI and NRTI resistance after first-line virologic failure was associated with higher VL at study entry. Thirty-two percent of individuals remained fully susceptible to etravirine and rilpivirine, protease inhibitor resistance was rare. Some level of susceptibility to NRTI remained; however, VL monitoring and earlier virologic failure detection may result in lower NRTI resistance. PMID:24795328

Antiretroviral drug susceptibility among drug-naive adults with recent HIV infection in Rakai, Uganda

PubMed Central

Eshleman, Susan H.; Laeyendecker, Oliver; Parkin, Neil; Huang, Wei; Chappey, Colombe; Paquet, Agnes C.; Serwadda, David; Reynolds, Steven J.; Kiwanuka, Noah; Quinn, Thomas C.; Gray, Ronald; Wawer, Maria

2009-01-01

Objective To analyze antiretroviral drug susceptibility in HIV from recently infected adults in Rakai, Uganda, prior to the availability of antiretroviral drug treatment. Methods Samples obtained at the time of HIV seroconversion (1998–2003) were analyzed using the GeneSeq HIV and PhenoSense HIV assays (Monogram Biosciences, Inc., South San Francisco, California, USA). Results Test results were obtained for 104 samples (subtypes: 26A, 1C, 66D, 9A/D, 1C/D, 1 intersubtype recombinant). Mutations used for genotypic surveillance of transmitted antiretroviral drug resistance were identified in six samples: three had nucleoside reverse transcriptase inhibitor (NRTI) surveillance mutations (two had M41L, one had K219R), and three had protease inhibitor surveillance mutations (I47V, F53L, N88D); none had nonnucleoside reverse transcriptase inhibitor (NNRTI) surveillance mutations. Other resistance-associated mutations were identified in some samples. However, none of the samples had a sufficient number of mutations to predict reduced antiretroviral drug susceptibility. Ten (9.6%) of the samples had reduced phenotypic susceptibility to at least one drug (one had partial susceptibility to didanosine, one had nevirapine resistance, and eight had resistance or partial susceptibility to at least one protease inhibitor). Fifty-three (51%) of the samples had hypersusceptibility to at least one drug (seven had zidovudine hypersusceptibility, 28 had NNRTI hypersusceptibility, 34 had protease inhibitor hypersusceptibility). Delavirdine hyper-susceptibility was more frequent in subtype A than D. In subtype D, efavirenz hypersusceptibility was associated with substitutions at codon 11 in HIV-reverse transcriptase. Conclusion Phenotyping detected reduced antiretroviral drug susceptibility and hypersusceptibility in HIV from some antiretroviral-naive Ugandan adults that was not predicted by genotyping. Phenotyping may complement genotyping for analysis of antiretroviral drug susceptibility in populations with nonsubtype B HIV infection. PMID:19276794

Antiretroviral drug susceptibility among drug-naive adults with recent HIV infection in Rakai, Uganda.

PubMed

Eshleman, Susan H; Laeyendecker, Oliver; Parkin, Neil; Huang, Wei; Chappey, Colombe; Paquet, Agnes C; Serwadda, David; Reynolds, Steven J; Kiwanuka, Noah; Quinn, Thomas C; Gray, Ronald; Wawer, Maria

2009-04-27

To analyze antiretroviral drug susceptibility in HIV from recently infected adults in Rakai, Uganda, prior to the availability of antiretroviral drug treatment. Samples obtained at the time of HIV seroconversion (1998-2003) were analyzed using the GeneSeq HIV and PhenoSense HIV assays (Monogram Biosciences, Inc., South San Francisco, California, USA). Test results were obtained for 104 samples (subtypes: 26A, 1C, 66D, 9A/D, 1C/D, 1 intersubtype recombinant). Mutations used for genotypic surveillance of transmitted antiretroviral drug resistance were identified in six samples: three had nucleoside reverse transcriptase inhibitor (NRTI) surveillance mutations (two had M41L, one had K219R), and three had protease inhibitor surveillance mutations (I47V, F53L, N88D); none had nonnucleoside reverse transcriptase inhibitor (NNRTI) surveillance mutations. Other resistance-associated mutations were identified in some samples. However, none of the samples had a sufficient number of mutations to predict reduced antiretroviral drug susceptibility. Ten (9.6%) of the samples had reduced phenotypic susceptibility to at least one drug (one had partial susceptibility to didanosine, one had nevirapine resistance, and eight had resistance or partial susceptibility to at least one protease inhibitor). Fifty-three (51%) of the samples had hypersusceptibility to at least one drug (seven had zidovudine hypersusceptibility, 28 had NNRTI hypersusceptibility, 34 had protease inhibitor hypersusceptibility). Delavirdine hypersusceptibility was more frequent in subtype A than D. In subtype D, efavirenz hypersusceptibility was associated with substitutions at codon 11 in HIV-reverse transcriptase. Phenotyping detected reduced antiretroviral drug susceptibility and hypersusceptibility in HIV from some antiretroviral-naive Ugandan adults that was not predicted by genotyping. Phenotyping may complement genotyping for analysis of antiretroviral drug susceptibility in populations with nonsubtype B HIV infection.

Highly potent artemisinin-derived dimers and trimers: Synthesis and evaluation of their antimalarial, antileukemia and antiviral activities.

PubMed

Reiter, Christoph; Fröhlich, Tony; Gruber, Lisa; Hutterer, Corina; Marschall, Manfred; Voigtländer, Cornelia; Friedrich, Oliver; Kappes, Barbara; Efferth, Thomas; Tsogoeva, Svetlana B

2015-09-01

New pharmaceutically active compounds can be obtained by modification of existing drugs to access more effective agents in the wake of drug resistance amongst others. To achieve this goal the concept of hybridization was established during the last decade. We employed this concept by coupling two artemisinin-derived precursors to obtain dimers or trimers with increased in vitro activity against Plasmodiumfalciparum 3D7 strain, leukemia cells (CCRF-CEM and multidrug-resistant subline CEM/ADR5000) and human cytomegalovirus (HCMV). Dimer 4 (IC50 of 2.6 nM) possess superior antimalarial activity compared with its parent compound artesunic acid(3) (IC50 of 9.0 nM). Dimer5 and trimers6 and 7 display superior potency against both leukemia cell lines (IC50 up to 0.002 μM for CCRF-CEM and IC50 up to 0.20 μM for CEM/ADR5000) and are even more active than clinically used doxorubicin (IC50 1.61 μM for CEM/ADR5000). With respect to anti-HCMV activity, trimer6 is the most efficient hybrid (IC50 0.04 μM) outperforming ganciclovir (IC50 2.6 μM), dihydroartemisinin(IC50 >10 μM) and artesunic acid (IC50 3.8 μM). Copyright © 2015 Elsevier Ltd. All rights reserved.

Remembering Jan Svoboda: A Personal Reflection.

PubMed

Weiss, Robin A

2018-04-18

The Czech scientist Jan Svoboda was a pioneer of Rous sarcoma virus (RSV). In the 1960s, before the discovery of reverse transcriptase, he demonstrated the long-term persistence of the viral genome in non-productive mammalian cells, and he supported the DNA provirus hypothesis of Howard Temin. He showed how the virus can be rescued in the infectious form and elucidated the replication-competent nature of the Prague strain of RSV later used for the identification of the src oncogene. His studies straddled molecular oncology and virology, and he remained an active contributor to the field until his death last year. Throughout the 50 years that I was privileged to know Svoboda as my mentor and friend, I admired his depth of scientific inquiry and his steadfast integrity in the face of political oppression.

Investigation of the presence of human or bovine respiratory syncytial virus in the lungs of mink (Neovison vison) with hemorrhagic pneumonia due to Pseudomonas aeruginosa.

PubMed

Salomonsen, Charlotte M; Breum, Solvej Ø; Larsen, Lars E; Jakobsen, Jeanette; Høiby, Niels; Hammer, Anne S

2012-11-26

Hemorrhagic pneumonia is a disease of farmed mink (Neovison vison) caused by Pseudomonas aeruginosa. The disease is highly seasonal in Danish mink with outbreaks occurring almost exclusively in the autumn. Human respiratory syncytial virus (RSV) has been shown to augment infection with P. aeruginosa in mice and to promote adhesion of P. aeruginosa to human respiratory cells. We tested 50 lung specimens from mink with hemorrhagic pneumonia for bovine RSV by reverse transcriptase polymerase chain reaction (PCR) and for human RSV by a commercial real-time PCR. RSV was not found. This study indicates that human and bovine RSV is not a major co-factor for development of hemorrhagic pneumonia in Danish mink.

Remembering Jan Svoboda: A Personal Reflection

PubMed Central

Weiss, Robin A.

2018-01-01

The Czech scientist Jan Svoboda was a pioneer of Rous sarcoma virus (RSV). In the 1960s, before the discovery of reverse transcriptase, he demonstrated the long-term persistence of the viral genome in non-productive mammalian cells, and he supported the DNA provirus hypothesis of Howard Temin. He showed how the virus can be rescued in the infectious form and elucidated the replication-competent nature of the Prague strain of RSV later used for the identification of the src oncogene. His studies straddled molecular oncology and virology, and he remained an active contributor to the field until his death last year. Throughout the 50 years that I was privileged to know Svoboda as my mentor and friend, I admired his depth of scientific inquiry and his steadfast integrity in the face of political oppression. PMID:29670049

Microwave-Assisted Rapid Enzymatic Synthesis of Nucleic Acids.

PubMed

Hari Das, Rakha; Ahirwar, Rajesh; Kumar, Saroj; Nahar, Pradip

2016-07-02

Herein we report microwave-induced enhancement of the reactions catalyzed by Escherichia coli DNA polymerase I and avian myeloblastosis virus-reverse transcriptase. The reactions induced by microwaves result in a highly selective synthesis of nucleic acids in 10-50 seconds. In contrast, same reactions failed to give desired reaction products when carried out in the same time periods, but without microwave irradiation. Each of the reactions was carried out for different duration of microwave exposure time to find the optimum reaction time. The products produced by the respective enzyme upon microwave irradiation of the reaction mixtures were identical to that produced by the conventional procedures. As the microwave-assisted reactions are rapid, microwave could be a useful alternative to the conventional and time consuming procedures of enzymatic synthesis of nucleic acids.

A duplex real-time RT-PCR assay for detecting H5N1 avian influenza virus and pandemic H1N1 influenza virus.

PubMed

Kang, Xiao-ping; Jiang, Tao; Li, Yong-qiang; Lin, Fang; Liu, Hong; Chang, Guo-hui; Zhu, Qing-yu; Qin, E-de; Qin, Cheng-feng; Yang, Yin-hui

2010-06-02

A duplex real-time reverse transcriptase polymerase chain reaction (RT-PCR) assay was improved for simultaneous detection of highly pathogenic H5N1 avian influenza virus and pandemic H1N1 (2009) influenza virus, which is suitable for early diagnosis of influenza-like patients and for epidemiological surveillance. The sensitivity of this duplex real-time RT-PCR assay was 0.02 TCID50 (50% tissue culture infective dose) for H5N1 and 0.2 TCID50 for the pandemic H1N1, which was the same as that of each single-target RT-PCR for pandemic H1N1 and even more sensitive for H5N1 with the same primers and probes. No cross reactivity of detecting other subtype influenza viruses or respiratory tract viruses was observed. Two hundred and thirty-six clinical specimens were tested by comparing with single real-time RT-PCR and result from the duplex assay was 100% consistent with the results of single real-time RT-PCR and sequence analysis.

In vitro evaluation of novel antiviral activities of 60 medicinal plants extracts against hepatitis B virus.

PubMed

Arbab, Ahmed Hassan; Parvez, Mohammad Khalid; Al-Dosari, Mohammed Salem; Al-Rehaily, Adnan Jathlan

2017-07-01

Currently, >35 Saudi Arabian medicinal plants are traditionally used for various liver disorders without a scientific rationale. This is the first experimental evaluation of the anti-hepatitis B virus (HBV) potential of the total ethanolic and sequential organic extracts of 60 candidate medicinal plants. The extracts were tested for toxicity on HepG2.2.15 cells and cytotoxicity concentration (CC 50 ) values were determined. The extracts were further investigated on HepG2.2.15 cells for anti-HBV activities by analyzing the inhibition of HBsAg and HBeAg production in the culture supernatants, and their half maximal inhibitory concentration (IC 50 ) and therapeutic index (TI) values were determined. Of the screened plants, Guiera senegalensis (dichloromethane extract, IC 50 =10.65), Pulicaria crispa (ethyl acetate extract, IC 50 =14.45), Coccinea grandis (total ethanol extract, IC 50 =31.57), Fumaria parviflora (hexane extract, IC 50 =35.44), Capparis decidua (aqueous extract, IC 50 =66.82), Corallocarpus epigeus (total ethanol extract, IC 50 =71.9), Indigofera caerulea (methanol extract, IC 50 =73.21), Abutilon figarianum (dichloromethane extract, IC 50 =99.76) and Acacia oerfota (total ethanol extract, IC 50 =101.46) demonstrated novel anti-HBV activities in a time- and dose-dependent manner. Further qualitative phytochemical analysis of the active extracts revealed the presence of alkaloids, tannins, flavonoids and saponins, which are attributed to antiviral efficacies. In conclusion, P. crispa, G. senegalensis and F. parviflora had the most promising anti-HBV potentials, including those of C. decidua , C. epigeus, A. figarianum , A. oerfota and I. caerulea with marked activities. However, a detailed phytochemical study of these extracts is essential to isolate the active principle(s) responsible for their novel anti-HBV potential.

Synthesis, docking and ADMET studies of novel chalcone triazoles for anti-cancer and anti-diabetic activity.

PubMed

Chinthala, Yakaiah; Thakur, Sneha; Tirunagari, Shalini; Chinde, Srinivas; Domatti, Anand Kumar; Arigari, Niranjana Kumar; K V N S, Srinivas; Alam, Sarfaraz; Jonnala, Kotesh Kumar; Khan, Feroz; Tiwari, Ashok; Grover, Paramjit

2015-03-26

A series of novel chalcone-triazole derivatives were synthesized and screened for in vitro anticancer activity on the human cancer cell lines IMR32 (neuroblastoma), HepG2 (hepatoma) and MCF-7 (breast adenocarcinoma), DU-145 (prostate carcinoma), and A549 (lung adenocarcinoma). Among the tested compounds, 4r showed the most promising anticancer activity in all the cell lines whereas, compounds 4c (IC50 65.86 μM), 4e (IC50 66.28 μM), 4o (IC50 35.81 μM), 4q (IC50 50.82 μM) and 4s (IC50 48.63 μM) showed better activity than the standard doxorubicin (IC50 69.33 μM) in A549 cell line alone. Rat intestinal α-glucosidase inhibitory activity of the synthesized derivatives showed 4m (IC50 67.77 μM), 4p (IC50 74.94 in μM) and 4s (IC50 102.10 μM) as most active compared to others. The in silico docking of synthesized derivatives 4a-4t with DNA topoisomerase IIα revealed the LibDock score in the range of 71.2623-118.29 whereas, compounds 4h, 4m, 4p and 4s with docking target α-glucosidase were in the range of 100.372-107.784. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

DMS-MaPseq for genome-wide or targeted RNA structure probing in vivo.

PubMed

Zubradt, Meghan; Gupta, Paromita; Persad, Sitara; Lambowitz, Alan M; Weissman, Jonathan S; Rouskin, Silvi

2017-01-01

Coupling of structure-specific in vivo chemical modification to next-generation sequencing is transforming RNA secondary structure studies in living cells. The dominant strategy for detecting in vivo chemical modifications uses reverse transcriptase truncation products, which introduce biases and necessitate population-average assessments of RNA structure. Here we present dimethyl sulfate (DMS) mutational profiling with sequencing (DMS-MaPseq), which encodes DMS modifications as mismatches using a thermostable group II intron reverse transcriptase. DMS-MaPseq yields a high signal-to-noise ratio, can report multiple structural features per molecule, and allows both genome-wide studies and focused in vivo investigations of even low-abundance RNAs. We apply DMS-MaPseq for the first analysis of RNA structure within an animal tissue and to identify a functional structure involved in noncanonical translation initiation. Additionally, we use DMS-MaPseq to compare the in vivo structure of pre-mRNAs with their mature isoforms. These applications illustrate DMS-MaPseq's capacity to dramatically expand in vivo analysis of RNA structure.

The unusually large Plasmodium telomerase reverse-transcriptase localizes in a discrete compartment associated with the nucleolus

PubMed Central

Figueiredo, Luisa M.; Rocha, Eduardo P. C.; Mancio-Silva, Liliana; Prevost, Christine; Hernandez-Verdun, Danièle; Scherf, Artur

2005-01-01

Telomerase replicates chromosome ends, a function necessary for maintaining genome integrity. We have identified the gene that encodes the catalytic reverse transcriptase (RT) component of this enzyme in the malaria parasite Plasmodium falciparum (PfTERT) as well as the orthologous genes from two rodent and one simian malaria species. PfTERT is predicted to encode a basic protein that contains the major sequence motifs previously identified in known telomerase RTs (TERTs). At ∼2500 amino acids, PfTERT is three times larger than other characterized TERTs. We observed remarkable sequence diversity between TERT proteins of different Plasmodial species, with conserved domains alternating with hypervariable regions. Immunofluorescence analysis revealed that PfTERT is expressed in asexual blood stage parasites that have begun DNA synthesis. Surprisingly, rather than at telomere clusters, PfTERT typically localizes into a discrete nuclear compartment. We further demonstrate that this compartment is associated with the nucleolus, hereby defined for the first time in P.falciparum. PMID:15722485

Structural investigation of HIV-1 nonnucleoside reverse transcriptase inhibitors: 2-Aryl-substituted benzimidazoles

NASA Astrophysics Data System (ADS)

Ziółkowska, Natasza E.; Michejda, Christopher J.; Bujacz, Grzegorz D.

2009-11-01

Acquired immunodeficiency syndrome (AIDS) caused by the human immunodeficiency virus (HIV) is one of the most destructive epidemics in history. Inhibitors of HIV enzymes are the main targets to develop drugs against that disease. Nonnucleoside reverse transcriptase inhibitors of HIV-1 (NNRTIs) are potentially effective and nontoxic. Structural studies provide information necessary to design more active compounds. The crystal structures of four NNRTI derivatives of 2-aryl-substituted N-benzyl-benzimidazole are presented here. Analysis of the geometrical parameters shows that the structures of the investigated inhibitors are rigid. The important geometrical parameter is the dihedral angle between the planes of the π-electron systems of the benzymidazole and benzyl moieties. The values of these dihedral angles are in a narrow range for all investigated inhibitors. There is no significant difference between the structure of the free inhibitor and the inhibitor in the complex with RT HIV-1. X-ray structures of the investigated inhibitors are a good basis for modeling enzyme-inhibitor interactions in rational drug design.

Intracellular studies of the nucleoside reverse transcriptase inhibitor active metabolites: a review.

PubMed

Rodriguez Orengo, J F; Santana, J; Febo, I; Diaz, C; Rodriguez, J L; Garcia, R; Font, E; Rosario, O

2000-03-01

Nucleoside reverse transcriptase inhibitors (NRTIs) plasma concentrations do not correlate with clinical efficacy or toxicity. These agents need to be phosphorylated to become active against HIV-infection. Thus, the characterization of the NRTIs intracellular metabolite pharmacological parameters will provide a better understanding that could lead to the development of more rational dose regimens in the HIV-infected population. Furthermore, intracellular measurements of NRTIs may provide a better marker with respect to clinical efficacy and toxicity than plasma concentrations. Thus, in this article we review the latest information regarding the intracellular pharmacological parameters of zidovudine (ZDV) and lamivudine (3TC) active metabolites in HIV-infected patients including the results from our recent clinical studies. We will start the discussion with ZDV and 3TC clinical efficacy, followed by systemic pharmacokinetics studies. We will then discuss the in vitro and in vivo intracellular studies with particular emphasis in the method development to measure these metabolites and we will conclude with the most current data from our clinical trials.

Molecular Epidemiology of Norovirus Outbreaks in Norway during 2000 to 2005 and Comparison of Four Norovirus Real-Time Reverse Transcriptase PCR Assays

PubMed Central

Vainio, Kirsti; Myrmel, Mette

2006-01-01

During the period from January 2000 to August 2005 a total of 204 outbreaks of norovirus gastroenteritis were diagnosed at the Norwegian Institute of Public Health. A clear increase in the norovirus activity was seen in healthcare institutions during the winter seasons. Polymerase sequence analysis of norovirus strains from 122 outbreaks showed that 112 were caused by GII strains (91.8%). Two norovirus variants seen during the study period—GIIb and GII.4—were predominant between January 2000 and September 2002, whereas GII.4 was predominant from September 2002 onward. The highest norovirus activity was seen during the 2002-2003 and 2004-2005 seasons with the emergence of new GII.4 variants. This study describes the molecular epidemiology of norovirus strains circulating in Norway during the five previous seasons and compares four norovirus real-time reverse transcriptase PCR assays. A suitable assay for routine diagnostics is suggested. PMID:17021099

Gene 2 of the sigma rhabdovirus genome encodes the P protein, and gene 3 encodes a protein related to the reverse transcriptase of retroelements.

PubMed

Landès-Devauchelle, C; Bras, F; Dezélée, S; Teninges, D

1995-11-10

The nucleotide sequence of the genes 2 and 3 of the Drosophila rhabdovirus sigma was determined from cDNAs to viral genome and poly(A)+ mRNAs. Gene 2 comprises 1032 nucleotides and contains a long ORF encoding a molecular weight 35,208 polypeptide present in infected cells and in virions which migrates in SDS-PAGE as a doublet of M(r) about 60 kDa. The distribution of acidic charges as well as the electrophoretic properties of the protein are characteristic of the rhabdovirus P proteins. Gene 3 comprises 923 nucleotides and contains a long ORF capable of coding a polypeptide of 298 amino acids of MW 33,790. The putative protein (PP3) is similar in size to a minor component of the virions. Computer analysis shows that the sequence of PP3 contains three motifs related to the conserved motifs of reverse transcriptases.

TOPICAL TENOFOVIR, A MICROBICIDE EFFECTIVE AGAINST HIV, INHIBITS HERPES SIMPLEX VIRUS-2 REPLICATION

PubMed Central

Andrei, Graciela; Lisco, Andrea; Vanpouille, Christophe; Introini, Andrea; Balestra, Emanuela; van den Oord, Joost; Cihlar, Tomas; Perno, Carlo-Federico; Snoeck, Robert; Margolis, Leonid; Balzarini, Jan

2011-01-01

SUMMARY The HIV reverse transcriptase inhibitor tenofovir, was recently formulated into a vaginal gel for use as a microbicide. In human trials, a 1% tenofovir gel inhibited HIV sexual transmission by 39% and surprisingly herpes simplex virus-2 (HSV-2) transmission by 51%. We demonstrate that the concentration achieved intravaginally with a 1% tenofovir topical gel has direct anti-herpetic activity. Tenofovir inhibits the replication of HSV clinical isolates in human embryonic fibroblasts, keratinocytes, and organotypic epithelial 3D-rafts, decreases HSV replication in human lymphoid and cervical tissues ex vivo, and delays HSV-induced lesions and death of topically treated HSV-infected mice. The active tenofovir metabolite inhibits HSV DNA-polymerase and HIV reverse transcriptase. Tenofovir must be topically administered to achieve concentrations, which are higher than systemic levels after oral treatment, that exert these dual antiviral effects. These findings indicate that a single topical treatment, like tenofovir, can inhibit the transmission of HIV and its co-pathogens. PMID:22018238

Reverse transcriptase genes are highly abundant and transcriptionally active in marine plankton assemblages

PubMed Central

Lescot, Magali; Hingamp, Pascal; Kojima, Kenji K; Villar, Emilie; Romac, Sarah; Veluchamy, Alaguraj; Boccara, Martine; Jaillon, Olivier; Iudicone, Daniele; Bowler, Chris; Wincker, Patrick; Claverie, Jean-Michel; Ogata, Hiroyuki

2016-01-01

Genes encoding reverse transcriptases (RTs) are found in most eukaryotes, often as a component of retrotransposons, as well as in retroviruses and in prokaryotic retroelements. We investigated the abundance, classification and transcriptional status of RTs based on Tara Oceans marine metagenomes and metatranscriptomes encompassing a wide organism size range. Our analyses revealed that RTs predominate large-size fraction metagenomes (>5 μm), where they reached a maximum of 13.5% of the total gene abundance. Metagenomic RTs were widely distributed across the phylogeny of known RTs, but many belonged to previously uncharacterized clades. Metatranscriptomic RTs showed distinct abundance patterns across samples compared with metagenomic RTs. The relative abundances of viral and bacterial RTs among identified RT sequences were higher in metatranscriptomes than in metagenomes and these sequences were detected in all metatranscriptome size fractions. Overall, these observations suggest an active proliferation of various RT-assisted elements, which could be involved in genome evolution or adaptive processes of plankton assemblage. PMID:26613339

Expression and characterization of a novel reverse transcriptase of the LTR retrotransposon Tf1.

PubMed

Kirshenboim, Noa; Hayouka, Zvi; Friedler, Assaf; Hizi, Amnon

2007-09-30

The LTR retrotransposon of Schizosacharomyces pombe, Tf1, has several distinctive properties that can be related to the unique properties of its reverse transcriptase (RT). Consequently, we expressed, purified and studied the recombinant Tf1 RT. This monomeric protein possesses all activities typical to RTs: DNA and RNA-dependent DNA polymerase as well as an inherent ribonuclease H. The DNA polymerase activity shows preference to Mn(+)(2) or Mg(+)(2), depending on the substrate used, whereas the ribonuclease H strongly prefers Mn(+)(2). The most outstanding feature of Tf1 RT is its capacity to add non-templated nucleotides to the 3'-ends of the nascent DNA. This is mainly apparent in the presence of Mn(+)(2), as is the noticeable low fidelity of DNA synthesis. In all, Tf1 RT has a marked infidelity in synthesizing DNA at template ends, a phenomenon that can explain, as discussed herein, some of the features of Tf1 replication in the host cells.

The future of pre-exposure prophylaxis (PrEP) for human immunodeficiency virus (HIV) infection.

PubMed

Özdener, Ayşe Elif; Park, Tae Eun; Kalabalik, Julie; Gupta, Rachna

2017-05-01

People at high risk for HIV acquisition should be offered pre-exposure prophylaxis (PrEP). Tenofovir disoproxil fumarate (TDF)/emtricitabine (FTC) is currently the only medication recommended for pre-exposure prophylaxis (PrEP) by the Centers for Disease Control and Prevention (CDC) in people at high risk for HIV acquisition. This article will review medications currently under investigation and the future landscape of PrEP therapy. Areas covered: This article will review clinical trials that have investigated nontraditional regimens of TDF/FTC, antiretroviral agents from different drug classes such as integrase strand transfer inhibitors (INSTI), nucleoside reverse transcriptase inhibitors (NRTI), and non-nucleoside reverse transcriptase inhibitors (NNRTI) as potential PrEP therapies. Expert commentary: Currently, there are several investigational drugs in the pipeline for PrEP against HIV infection. Increased utilization of PrEP therapy depends on provider identification of people at high risk for HIV transmission. Advances in PrEP development will expand options and access for people and reduce the risk of HIV acquisition.

Snapshot of the equilibrium dynamics of a drug bound to HIV-1 reverse transcriptase

NASA Astrophysics Data System (ADS)

Kuroda, Daniel G.; Bauman, Joseph D.; Challa, J. Reddy; Patel, Disha; Troxler, Thomas; Das, Kalyan; Arnold, Eddy; Hochstrasser, Robin M.

2013-03-01

The anti-AIDS drug rilpivirine undergoes conformational changes to bind HIV-1 reverse transcriptase (RT), which is an essential enzyme for the replication of HIV. These changes allow it to retain potency against mutations that otherwise would render the enzyme resistant. Here we report that water molecules play an essential role in this binding process. Femtosecond experiments and theory expose the molecular level dynamics of rilpivirine bound to HIV-1 RT. Two nitrile substituents, one on each arm of the drug, are used as vibrational probes of the structural dynamics within the binding pocket. Two-dimensional vibrational echo spectroscopy reveals that one nitrile group is unexpectedly hydrogen-bonded to a mobile water molecule, not identified in previous X-ray structures. Ultrafast nitrile-water dynamics are confirmed by simulations. A higher (1.51 Å) resolution X-ray structure also reveals a water-drug interaction network. Maintenance of a crucial anchoring hydrogen bond may help retain the potency of rilpivirine against pocket mutations despite the structural variations they cause.

Pausing kinetics dominates strand-displacement polymerization by reverse transcriptase

PubMed Central

Malik, Omri; Khamis, Hadeel; Rudnizky, Sergei; Marx, Ailie

2017-01-01

Abstract Reverse transcriptase (RT) catalyzes the conversion of the viral RNA into an integration-competent double-stranded DNA, with a variety of enzymatic activities that include the ability to displace a non-template strand concomitantly with polymerization. Here, using high-resolution optical tweezers to follow the activity of the murine leukemia Virus RT, we show that strand-displacement polymerization is frequently interrupted. Abundant pauses are modulated by the strength of the DNA duplex ∼8 bp ahead, indicating the existence of uncharacterized RT/DNA interactions, and correspond to backtracking of the enzyme, whose recovery is also modulated by the duplex strength. Dissociation and reinitiation events, which induce long periods of inactivity and are likely the rate-limiting step in the synthesis of the genome in vivo, are modulated by the template structure and the viral nucleocapsid protein. Our results emphasize the potential regulatory role of conserved structural motifs, and may provide useful information for the development of potent and specific inhibitors. PMID:28973474

Reverse transcriptase inhibitors as microbicides.

PubMed

Lewi, Paul; Heeres, Jan; Ariën, Kevin; Venkatraj, Muthusamy; Joossens, Jurgen; Van der Veken, Pieter; Augustyns, Koen; Vanham, Guido

2012-01-01

The CAPRISA 004 study in South Africa has accelerated the development of vaginal and rectal microbicides containing antiretrovirals that target specific enzymes in the reproduction cycle of HIV, especially reverse transcriptase inhibitors (RTI). In this review we discuss the potential relevance of HIV-1 RTIs as microbicides, focusing in the nucleotide RTI tenofovir and six classes of nonnucleoside RTIs (including dapivirine, UC781, urea and thiourea PETTs, DABOs and a pyrimidinedione). Although tenofovir and dapivirine appear to be most advanced in clinical trials as potential microbicides, several issues remain unresolved, e.g., the importance of nonhuman primates as a "gatekeeper" for clinical trials, the emergence and spread of drug-resistant mutants, the combination of microbicides that target different phases of viral reproduction and the accessibility to microbicides in low-income countries. Thus, here we discuss the latest research on RTI as microbicides in the light of the continuing spread of the HIV pandemic from the point of view of medicinal chemistry, virological, and pharmaceutical studies.

Expanded-spectrum nonnucleoside reverse transcriptase inhibitors inhibit clinically relevant mutant variants of human immunodeficiency virus type 1.

PubMed

Corbett, J W; Ko, S S; Rodgers, J D; Jeffrey, S; Bacheler, L T; Klabe, R M; Diamond, S; Lai, C M; Rabel, S R; Saye, J A; Adams, S P; Trainor, G L; Anderson, P S; Erickson-Viitanen, S K

1999-12-01

A research program targeted toward the identification of expanded-spectrum nonnucleoside reverse transcriptase inhibitors which possess increased potency toward K103N-containing mutant human immunodeficiency virus (HIV) and which maintain pharmacokinetics consistent with once-a-day dosing has resulted in the identification of the 4-cyclopropylalkynyl-4-trifluoromethyl-3, 4-dihydro-2(1H)quinazolinones DPC 961 and DPC 963 and the 4-cyclopropylalkenyl-4-trifluoromethyl-3, 4-dihydro-2(1H)quinazolinones DPC 082 and DPC 083 for clinical development. DPC 961, DPC 963, DPC 082, and DPC 083 all exhibit low-nanomolar potency toward wild-type virus, K103N and L100I single-mutation variants, and many multiply amino acid-substituted HIV type 1 mutants. This high degree of potency is combined with a high degree of oral bioavailability, as demonstrated in rhesus monkeys and chimpanzees, and with plasma serum protein binding that can result in significant free levels of drug.

The ORF1 Protein Encoded by LINE-1: Structure and Function During L1 Retrotransposition

PubMed Central

Martin, Sandra L.

2006-01-01

LINE-1, or L1 is an autonomous non-LTR retrotransposon in mammals. Retrotransposition requires the function of the two, L1-encoded polypeptides, ORF1p and ORF2p. Early recognition of regions of homology between the predicted amino acid sequence of ORF2 and known endonuclease and reverse transcriptase enzymes led to testable hypotheses regarding the function of ORF2p in retrotransposition. As predicted, ORF2p has been demonstrated to have both endonuclease and reverse transcriptase activities. In contrast, no homologs of known function have contributed to our understanding of the function of ORF1p during retrotransposition. Nevertheless, significant advances have been made such that we now know that ORF1p is a high affinity RNA binding protein that forms a ribonucleoprotein particle together with L1 RNA. Furthermore, ORF1p is a nucleic acid chaperone and this nucleic acid chaperone activity is required for L1 retrotransposition. PMID:16877816

Sodium-hydrogen exchanger inhibitory potential of Malus domestica, Musa × paradisiaca, Daucus carota, and Symphytum officinale.

PubMed

Verma, Vivek; Singh, Nirmal; Jaggi, Amteshwar Singh

2014-02-01

The involvement of sodium-hydrogen exchangers (NHE) has been described in the pathophysiology of diseases including ischemic heart and brain diseases, cardiomyopathy, congestive heart failure, epilepsy, dementia, and neuropathic pain. Synthetic NHE inhibitors have not achieved much clinical success; therefore, plant-derived phytoconstituents may be explored as NHE inhibitors. In the present study, the NHE inhibitory potential of hydroalcoholic and alkaloidal fractions of Malus domestica, Musa × paradisiaca, Daucus carota, and Symphytum officinale was evaluated. The different concentrations of hydroalcoholic and alkaloidal extracts of the selected plants were evaluated for their NHE inhibitory activity in the platelets using the optical swelling assay. Among the hydroalcoholic extracts, the highest NHE inhibitory activity was shown by M. domestica (IC50=2.350 ± 0.132 μg/mL) followed by Musa × paradisiaca (IC50=7.967 ± 0.451 μg/mL), D. carota (IC50=37.667 ± 2.517 μg/mL), and S. officinale (IC50=249.330 ± 1.155 μg/mL). Among the alkaloidal fractions, the highest NHE inhibitory activity was shown by the alkaloidal fraction of Musa × paradisiacal (IC50=0.010 ± 0.001 μg/mL) followed by D. carota (IC50=0.024 ± 0.002 μg/mL), M. domestica (IC50=0.031 ± 0.005 μg/mL), and S. officinale (IC50=4.233 ± 0.379 μg/mL). The IC50 of alkaloidal fractions was comparable to the IC50 of synthetic NHE inhibitor, EIPA [5-(N-ethyl-N-isopropyl)amiloride] (IC50=0.033 ± 0.004 μg/mL). It may be concluded that the alkaloidal fractions of these plants possess potent NHE inhibitory activity and may be exploited for their therapeutic potential in NHE activation-related pathological complications.

Impact of Noncoding Satellite Repeats on Pancreatic Cancer Metastasis

DTIC Science & Technology

2014-09-01

nucleoside reverse transcriptase inhibitor ddC as a small molecule inhibitor of HSATII reverse transcription. Initial data indicates there are anti...proliferative effects of ddC in cancer cell lines. We will evaluate ddC and anti-sense locked nucleic acids as methods for inhibiting this process and...of these hybrids, we tested the effect of the nucleoside analog RT inhibitor (NRTI) 2’,3’-dideoxycytidine ( ddC ) in COLO205 cells (Fig. 2e). Notably

Synergistic effect of sevoflurane and isoflurane on inhibition of the adult-type muscle nicotinic acetylcholine receptor by rocuronium.

PubMed

Liu, Li; Li, Wei; Wei, Ke; Cao, Jun; Luo, Jie; Wang, Bin; Min, Su

2013-06-01

Inhaled anesthetics increase the incidence of postoperative residual neuromuscular blockade, and the mechanism is still unclear. We have investigated the synergistic effect of low-concentration inhaled anesthetics and rocuronium on inhibition of the inward current of the adult-type muscle nicotinic acetylcholine receptor (ε-nAChR). Adult-type mouse muscle ε-nAChR was expressed in HEK293 cells by liposome transfection. The inward current of the ε-nAChR was activated by use of 10 μmol/L acetylcholine alone or in combination with different concentrations of sevoflurane, isoflurane, or rocuronium. The concentration-response curves of five cells were constructed, and the data yielded the 5, 25, and 50 % inhibitory concentrations (IC5, IC25, and IC50, respectively) for single-drug application. Subsequently, the functional channels were perfused by adding 0.5 IC5 of either sevoflurane or isoflurane (aqueous concentrations 140 and 100 μmol/L, respectively) to the solution, followed by addition of IC5, IC25, or IC50 rocuronium. The amount of inhibition was calculated to quantify their synergistic effect. The inhibitory effect of rocuronium was enhanced by sevoflurane or isoflurane in a concentration-dependent manner. Sevoflurane or isoflurane (0.5 IC5) with rocuronium at IC5, IC25, and IC50 synergistically inhibited the current amplitude of adult-type muscle ε-nAChR. When the IC5 of rocuronium was used, isoflurane had a stronger synergistic effect than sevoflurane (p < 0.05). When rocuronium was applied at higher concentrations (IC25 and IC50), sevoflurane had an effect similar to that of isoflurane. For both inhaled anesthetics, the synergistic effect was more intense for rocuronium at IC5 than for rocuronium at IC25 or IC50. Residual-concentration sevoflurane or isoflurane has a strong synergistic effect with rocuronium at clinically relevant residual concentrations. A lower rocuronium concentration resulted in a stronger synergistic effect.

TRIM25 is associated with cisplatin resistance in non-small-cell lung carcinoma A549 cell line via downregulation of 14-3-3σ.

PubMed

Qin, Xia; Qiu, Feng; Zou, Zhen

2017-11-04

Lung cancer, in particular, non-small cell lung cancer (NSCLC), is the leading cause of cancer-related mortality. Cis-Diamminedichloroplatinum (cisplatin, CDDP) as first-line chemotherapy for NSCLC, but resistance occurs frequently. We previously reported that Tripartite motif protein 25 (TRIM25) was highly expressed in cisplatin-resistant human lung adenocarcinoma A549 cells (A549/CDDP) in comparison with its parental A549 cells. Herein, we take a further step to demonstrate the association of TRIM25 and cisplatin resistance and also the underlying mechanisms. Knockdown of TRIM25 by RNA interference in A549/CDDP cells decreased half maximal inhibitory concentration (IC 50 ) values and promoted apoptosis in response to cisplatin, whereas overexpression of TRIM25 had opposite effects. More importantly, we found that concomitant knockdown of 14-3-3σ and TRIM25 absolutely reversed the decreased MDM2, increased p53, increased cleaved-Capsese3 and decreased IC 50 value induced by knockdown of TRIM25 individually, suggesting that TRIM25 mediated cisplatin resistance primarily through downregulation of 14-3-3σ. Our results indicate that TRIM25 is associated with cisplatin resistance and 14-3-3σ-MDM2-p53 signaling pathway is involved in this process, suggesting targeting TRIM25 may be a potential strategy for the reversal of cisplatin resistance. Copyright © 2017 Elsevier Inc. All rights reserved.

Lignan from Thyme Possesses Inhibitory Effect on ASIC3 Channel Current*

PubMed Central

Dubinnyi, Maxim A.; Osmakov, Dmitry I.; Koshelev, Sergey G.; Kozlov, Sergey A.; Andreev, Yaroslav A.; Zakaryan, Naira A.; Dyachenko, Igor A.; Bondarenko, Dmitry A.; Arseniev, Alexander S.; Grishin, Eugene V.

2012-01-01

A novel compound was identified in the acidic extract of Thymus armeniacus collected in the Lake Sevan region of Armenia. This compound, named “sevanol,” to our knowledge is the first low molecular weight natural molecule that has a reversible inhibition effect on both the transient and the sustained current of human ASIC3 channels expressed in Xenopus laevis oocytes. Sevanol completely blocked the transient component (IC50 353 ± 23 μm) and partially (∼45%) inhibited the amplitude of the sustained component (IC50 of 234 ± 53 μm). Other types of acid-sensing ion channel (ASIC) channels were intact to sevanol application, except ASIC1a, which showed more than six times less affinity to it as compared with the inhibitory action on the ASIC3 channel. To elucidate the structure of sevanol, the set of NMR spectra in two solvents (d6-DMSO and D2O) was collected, and the complete chemical structure was confirmed by liquid chromatography-mass spectrometry with electrospray ionization (LC-ESI+-MS) fragmentation. This compound is a new lignan built up of epiphyllic acid and two isocitryl esters in positions 9 and 10. In vivo administration of sevanol (1–10 mg/kg) significantly reversed thermal hyperalgesia induced by complete Freund's adjuvant injection and reduced response to acid in a writhing test. Thus, we assume the probable considerable role of sevanol in known analgesic and anti-inflammatory properties of thyme. PMID:22854960

Fused heterocycles bearing bridgehead nitrogen as potent HIV-1 NNRTIs. Part 4: design, synthesis and biological evaluation of novel imidazo[1,2-a]pyrazines.

PubMed

Huang, Boshi; Liang, Xin; Li, Cuicui; Chen, Wenmin; Liu, Tao; Li, Xiao; Sun, Yueyue; Fu, Lu; Liu, Huiqing; De Clercq, Erik; Pannecouque, Christophe; Zhan, Peng; Liu, Xinyong

2015-03-26

Through a structure-guided core-refining approach, a series of novel imidazo[1,2-a]pyrazine derivatives were designed, synthesized and evaluated as HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs). Biological results of antiviral assay in MT-4 cell cultures showed that 12 target compounds displayed moderate activities against wild-type (wt) HIV-1 strain (IIIB) with EC50 values ranging from 0.26 μM to 19 μM. Among them, 4a and 5a were found to be the two most active analogues possessing EC50 values of 0.26 μM and 0.32 μM respectively, comparable to delavirdine (DLV, EC50 = 0.54 μM) and nevirapine (NVP, EC50 = 0.31 μM) in a cell-based assay. Additionally, 9 compounds showed RT inhibitory activity superior to that of NVP. Moreover, some predicted drug-like properties of representative compounds 4a and 5a, as well as the structure-activity relationship (SAR) analysis were discussed in detail. The binding mode of compound 4a was investigated by molecular simulation studies. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Water-soluble polysaccharides from agro-industrial by-products: functional and biological properties.

PubMed

Sila, Assaâd; Bayar, Nadia; Ghazala, Imen; Bougatef, Ali; Ellouz-Ghorbel, Raoudha; Ellouz-Chaabouni, Semia

2014-08-01

Water-soluble polysaccharides were isolated from almond (AWSP) and pistachio (PWSP) juice processing by-products. Their chemical and physical characteristics were determined using NMR and Infrared spectroscopic analysis. The complexities of the spectra reflected the heterogeneity of these polysaccharides. The ACE inhibitory activities (IC50 AWSP=2.81mgmL(-1) and IC50 PWSP=2.59mgmL(-1)) and antioxidant properties of AWSP and PWSP were investigated based on the DPPH radical-scavenging capacity assay (IC50 AWSP=2.87mgmL(-1) and IC50 PWSP=1.61mgmL(-1)). Reducing power, β-carotene bleaching inhibition (IC50AWSP=4.46mgmL(-1) and IC50 PWSP=3.39mgmL(-1)), and ferrous chelating assays (IC50 AWSP=0.22mgmL(-1) and IC50 PWSP=0.19mgmL(-1)) were also performed. The findings revealed that water-soluble polysaccharides exhibited antioxidant and antihypertensive activities. AWSP and PWSP showed excellent interfacial concentration-dependent properties. Overall, the results suggested that both AWSP and PWSP are promising sources of natural antioxidants and ACE inhibitory agents and could, therefore, be used as alternative additives in food, pharmaceutical and cosmetic preparations. Copyright © 2014 Elsevier B.V. All rights reserved.

Preformulation studies of EFdA, a novel nucleoside reverse transcriptase inhibitor for HIV prevention

PubMed Central

Zhang, Wei; Parniak, Michael A.; Mitsuya, Hiroaki; Sarafianos, Stefan G.; Graebing, Phillip W.; Rohan, Lisa C.

2014-01-01

4′-Ethynyl-2-fluoro-2′-deoxyadenosine (EFdA) is a novel nucleoside analog of great interest because of its superior activity against wild-type and multidrug-resistant HIV-1 strains, and favorable safety profiles in vitro and in vivo. The aim of this work was to provide preformulation information of EFdA important for delivery system development. A simple, accurate and specific reverse-phase high performance liquid chromatographic (RP-HPLC) method with UV detection was developed for quantification of EFdA. In addition, physicochemical characterizations including pH solubility profile, octanol/water partition coefficient (Log Po/w), DSC analysis, field emission scanning electron microscopy, and stability studies under various conditions were conducted. EFdA existed in planar or flake shape, with a melting point of ~130 °C, and had a pH dependent solubility. The log Po/w value of EFdA was −1.19. The compound was stable upon exposure to pH levels from 3 to 9 and showed good stability at elevated temperature (65 °C). In vitro cytotoxicity assessments were performed in two different epithelial cell lines. In cell-based studies, the EFdA selectivity index (50% cytotoxic concentration [CC50] values/50% effective concentration [EC50]) was found to be greater than 1 × 103. Permeability studies using cell- and tissue-based models showed that EFdA had an apparent permeability coefficient (Papp) <1 × 10−6cm/s and that the paracelluar pathway was the dominant transport route for EFdA. Overall, EFdA possesses favorable characteristics for further formulation development. PMID:23841536

Preformulation studies of EFdA, a novel nucleoside reverse transcriptase inhibitor for HIV prevention.

PubMed

Zhang, Wei; Parniak, Michael A; Mitsuya, Hiroaki; Sarafianos, Stefan G; Graebing, Phillip W; Rohan, Lisa C

2014-08-01

4'-Ethynyl-2-fluoro-2'-deoxyadenosine (EFdA) is a novel nucleoside analog of great interest because of its superior activity against wild-type and multidrug-resistant HIV-1 strains, and favorable safety profiles in vitro and in vivo. The aim of this work was to provide preformulation information of EFdA important for delivery system development. A simple, accurate and specific reverse-phase high performance liquid chromatographic (RP-HPLC) method with UV detection was developed for quantification of EFdA. In addition, physicochemical characterizations including pH solubility profile, octanol/water partition coefficient (Log Po/w), DSC analysis, field emission scanning electron microscopy, and stability studies under various conditions were conducted. EFdA existed in planar or flake shape, with a melting point of ∼130 °C, and had a pH dependent solubility. The log Po/w value of EFdA was -1.19. The compound was stable upon exposure to pH levels from 3 to 9 and showed good stability at elevated temperature (65 °C). In vitro cytotoxicity assessments were performed in two different epithelial cell lines. In cell-based studies, the EFdA selectivity index (50% cytotoxic concentration [CC50] values/50% effective concentration [EC50]) was found to be greater than 1 × 10(3). Permeability studies using cell- and tissue-based models showed that EFdA had an apparent permeability coefficient (Papp) <1 × 10(-6)cm/s and that the paracelluar pathway was the dominant transport route for EFdA. Overall, EFdA possesses favorable characteristics for further formulation development.

Differential modulation of microglia superoxide anion and thromboxane B2 generation by the marine manzamines

PubMed Central

Mayer, Alejandro MS; Hall, Mary L; Lynch, Sean M; Gunasekera, Sarath P; Sennett, Susan H; Pomponi, Shirley A

2005-01-01

Background Thromboxane B2 (TXB2) and superoxide anion (O2-) are neuroinflammatory mediators that appear to be involved in the pathogenesis of several neurodegenerative diseases. Because activated-microglia are the main source of TXB2 and O2- in these disorders, modulation of their synthesis has been hypothesized as a potential therapeutic approach for neuroinflammatory disorders. Marine natural products have become a source of novel agents that modulate eicosanoids and O2- generation from activated murine and human leukocytes. With the exception of manzamine C, all other manzamines tested are characterized by a complex pentacyclic diamine linked to C-1 of the β-carboline moiety. These marine-derived alkaloids have been reported to possess a diverse range of bioactivities including anticancer, immunostimulatory, insecticidal, antibacterial, antimalarial and antituberculosis activities. The purpose of this investigation was to conduct a structure-activity relationship study with manzamines (MZ) A, B, C, D, E and F on agonist-stimulated release of TXB2 and O2- from E. coli LPS-activated rat neonatal microglia in vitro. Results The manzamines differentially attenuated PMA (phorbol 12-myristate 13-acetate)-stimulated TXB2 generation in the following order of decreasing potency: MZA (IC50 <0.016 μM) >MZD (IC50 = 0.23 μM) >MZB (IC50 = 1.6 μM) >MZC (IC50 = 2.98 μM) >MZE and F (IC50 >10 μM). In contrast, there was less effect on OPZ (opsonized zymosan)-stimulated TXB2 generation: MZB (IC50 = 1.44 μM) >MZA (IC50 = 3.16 μM) >MZC (IC50 = 3.34 μM) >MZD, MZE and MZF (IC50 >10 μM). Similarly, PMA-stimulated O2- generation was affected differentially as follows: MZD (apparent IC50<0.1 μM) >MZA (IC50 = 0.1 μM) >MZB (IC50 = 3.16 μM) >MZC (IC50 = 3.43 μM) >MZE and MZF (IC50 >10 μM). In contrast, OPZ-stimulated O2- generation was minimally affected: MZB (IC50 = 4.17 μM) >MZC (IC50 = 9.3 μM) >MZA, MZD, MZE and MZF (IC50 > 10 μM). From the structure-activity relationship perspective, contributing factors to the observed differential bioactivity on TXB2 and O2- generation are the solubility or ionic forms of MZA and D as well as changes such as saturation or oxidation of the β carboline or 8-membered amine ring. In contrast, the fused 13-membered macrocyclic and isoquinoline ring system, and any substitutions in these rings would not appear to be factors contributing to bioactivity. Conclusion To our knowledge, this is the first experimental study that demonstrates that MZA, at in vitro concentrations that are non toxic to E. coli LPS-activated rat neonatal microglia, potently modulates PMA-stimulated TXB2 and O2- generation. MZA may thus be a lead candidate for the development of novel therapeutic agents for the modulation of TXB2 and O2- release in neuroinflammatory diseases. Marine natural products provide a novel and rich source of chemical diversity that can contribute to the design and development of new and potentially useful anti-inflammatory agents to treat neurodegenerative diseases. PMID:15762999

Safety, tolerability and pharmacokinetics of doravirine, a novel HIV non-nucleoside reverse transcriptase inhibitor, after single and multiple doses in healthy subjects.

PubMed

Anderson, Matt S; Gilmartin, Jocelyn; Cilissen, Caroline; De Lepeleire, Inge; Van Bortel, Luc; Dockendorf, Marissa F; Tetteh, Ernestina; Ancona, June K; Liu, Rachael; Guo, Ying; Wagner, John A; Butterton, Joan R

2015-01-01

Doravirine is a novel non-nucleoside inhibitor of HIV-1 reverse transcriptase with potent activity against wild-type virus (95% inhibitory concentration 19 nM, 50% human serum). Doravirine has low potential to cause drug-drug interactions since it is primarily eliminated by oxidative metabolism and does not inhibit or significantly induce drug-metabolizing enzymes. The pharmacokinetics and safety of doravirine were investigated in two double-blind, dose-escalation studies in healthy males. Thirty-two subjects received single doses of doravirine (6-1,200 mg) or matching placebo tablets; 40 subjects received doravirine (30-750 mg) or matching placebo tablets once daily for 10 days. In addition, the effect of doravirine (120 mg for 14 days) on single-dose pharmacokinetics of the CYP3A substrate midazolam was evaluated (10 subjects). The maximum plasma concentration (Cmax) of doravirine was achieved within 1-5 h with an apparent terminal half-life of 12-21 h. Consistent with single-dose pharmacokinetics, steady state was achieved after approximately 7 days of once daily administration, with accumulation ratios (day 10/day 1) of 1.1-1.5 in the area under the plasma concentration-time curve during the dosing interval (AUC0-24 h), Cmax and trough plasma concentration (C24 h). All dose levels produced C24 h>19 nM. Administration of 50 mg doravirine with a high-fat meal was associated with slight elevations in AUC time zero to infinity (AUC0-∞) and C24 h with no change in Cmax. Midazolam AUC0-∞ was slightly reduced by coadministration of doravirine (geometric mean ratio 0.82, 90% CI 0.70, 0.97). There was no apparent relationship between adverse event frequency or intensity and doravirine dose. No rash or significant central nervous system events other than headache were reported. Doravirine is generally well tolerated in single doses up to 1,200 mg and multiple doses up to 750 mg once daily for up to 10 days, with a pharmacokinetic profile supportive of once-daily dosing. Doravirine at steady state slightly reduced the exposure of coadministered midazolam, to a clinically unimportant extent.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Jun Ho; College of Medicine, Korea University, Seoul 136-701; Kim, Tae Hyung

Mast cells, constituents of virtually all organs and tissues, are critical cells in IgE-mediated allergic responses. The aim of this study was to investigate the effect and mechanism of an indoxyl chromogenic compound, 5-bromo-4-chloro-3-indolyl 1,3-diacetate, CAC-0982, on IgE-mediated mast cell activation and allergic responses in mice. CAC-0982 reversibly suppressed antigen-stimulated degranulation in murine mast cells (IC{sub 50}, ~ 3.8 μM) and human mast cells (IC{sub 50}, ~ 3.0 μM). CAC-0982 also inhibited the expression and secretion of IL-4 and TNF-α in mast cells. Furthermore, CAC-0982 suppressed the mast cell-mediated allergic responses in mice in a dose-dependent manner (ED{sub 50} 27.9more » mg/kg). As for the mechanism, CAC-0982 largely suppressed the phosphorylation of Syk and its downstream signaling molecules, including LAT, Akt, Erk1/2, p38, and JNK. Notably, the tyrosine kinase assay of antigen-stimulated mast cells showed that CAC-0982 inhibited Fyn kinase, one of the upstream tyrosine kinases for Syk activation in mast cells. Taken together, these results suggest that CAC-0982 may be used as a new treatment for regulating IgE-mediated allergic diseases through the inhibition of the Fyn/Syk pathway in mast cells. - Highlights: • The anti-allergic effect of 5-bromo-4-chloro-3-indolyl 1,3-diacetate, CAC-0982, was measured. • CAC-0982 reversibly suppressed the activation of mast cells by IgE and antigen. • CAC-0982 inhibited passive cutaneous anaphylaxis in mice. • CAC-0982 suppresses mast cells through inhibition of Fyn activation in mast cells.« less

Marine-Derived Penicillium Species as Producers of Cytotoxic Metabolites

PubMed Central

Su, Mingzhi; Song, Shao-Jiang; Jung, Jee H.

2017-01-01

Since the discovery of penicillin, Penicillium has become one of the most attractive fungal genera for the production of bioactive molecules. Marine-derived Penicillium has provided numerous excellent pharmaceutical leads over the past decades. In this review, we focused on the cytotoxic metabolites * (* Cytotoxic potency was referred to five different levels in this review, extraordinary (IC50/LD50: <1 μM or 0.5 μg/mL); significant (IC50/LD50: 1~10 μM or 0.5~5 μg/mL); moderate (IC50/LD50: 10~30 μM or 5~15 μg/mL); mild (IC50/LD50: 30~50 μM or 15~25 μg/mL); weak (IC50/LD50: 50~100 μM or 25~50 μg/mL). The comparative potencies of positive controls were referred when they were available). produced by marine-derived Penicillium species, and on their cytotoxicity mechanisms, biosyntheses, and chemical syntheses. PMID:29064452

Chemical composition and in vitro antitrypanosomal activity of fractions of essential oil from Cymbopogon nardus L.

PubMed

Muhd Haffiz, J; Norhayati, I; Getha, K; Nor Azah, M A; Mohd Ilham, A; Lili Sahira, H; Roshan Jahn, M S; Muhd Syamil, A

2013-03-01

Essential oil from Cymbopogon nardus was evaluated for activity against Trypanosoma brucei brucei BS221 (IC50 = 0.31 ± 0.03 μg/mL) and cytotoxic effect on normal kidney (Vero) cells (IC50 = >100 μg/mL). The crude essential oil was subjected to various chromatography techniques afforded active sub fractions with antitrypanosomal activity; F4 (IC50 = 0.61 ± 0.06 μg/mL), F6 (IC50= 0.73 ± 0.33 μg/mL), F7 (IC50 = 1.15 ± 0 μg/mL) and F8 (IC50 = 1.11 ± 0.01 μg/mL). These active fractions did not exhibit any toxic effects against Vero cell lines and the chemical profiles investigation indicated presence of α-and γ-eudesmol, elemol, α-cadinol and eugenol by GC/MS analysis.

Long-term effectiveness of initiating non-nucleoside reverse transcriptase inhibitor- versus ritonavir-boosted protease inhibitor-based antiretroviral therapy: implications for first-line therapy choice in resource-limited settings

PubMed Central

Lima, Viviane D; Hull, Mark; McVea, David; Chau, William; Harrigan, P Richard; Montaner, Julio SG

2016-01-01

Introduction In many resource-limited settings, combination antiretroviral therapy (cART) failure is diagnosed clinically or immunologically. As such, there is a high likelihood that patients may stay on a virologically failing regimen for a substantial period of time. Here, we compared the long-term impact of initiating non-nucleoside reverse transcriptase inhibitor (NNRTI)- versus boosted protease inhibitor (bPI)-based cART in British Columbia (BC), Canada. Methods We followed prospectively 3925 ART-naïve patients who started NNRTIs (N=1963, 50%) or bPIs (N=1962; 50%) from 1 January 2000 until 30 June 2013 in BC. At six months, we assessed whether patients virologically failed therapy (a plasma viral load (pVL) >50 copies/mL), and we stratified them based on the pVL at the time of failure ≤500 versus >500 copies/mL. We then followed these patients for another six months and calculated their probability of achieving subsequent viral suppression (pVL <50 copies/mL twice consecutively) and of developing drug resistance. These probabilities were adjusted for fixed and time-varying factors, including cART adherence. Results At six months, virologic failure rates were 9.5 and 14.3 cases per 100 person-months for NNRTI and bPI initiators, respectively. NNRTI initiators who failed with a pVL ≤500 copies/mL had a 16% higher probability of achieving subsequent suppression at 12 months than bPI initiators (0.81 (25th–75th percentile 0.75–0.83) vs. 0.72 (0.61–0.75)). However, if failing NNRTI initiators had a pVL >500 copies/mL, they had a 20% lower probability of suppressing at 12 months than pVL-matched bPI initiators (0.37 (0.29–0.45) vs. 0.46 (0.38–0.54)). In terms of evolving HIV drug resistance, those who failed on NNRTI performed worse than bPI in all scenarios, especially if they failed with a viral load >500 copies/mL. Conclusions Our results show that patients who virologically failed at six months on NNRTI and continued on the same regimen had a lower probability of subsequently achieving viral suppression and a higher chance of evolving HIV drug resistance. These results suggest that improving access to regular virologic monitoring is critically important, especially if NNRTI-based cART is to remain a preferred choice for first-line therapy in resource-limited settings. PMID:27499064

Phenolic contents, antioxidant and anticholinesterase potentials of crude extract, subsequent fractions and crude saponins from Polygonum hydropiper L

PubMed Central

2014-01-01

Background We investigated Polygonum hydropiper L. (P. hydropiper) for phenolic contents, antioxidant, anticholinesterase activities, in an attempt to rationalize its use in neurological disorders. Methods Plant crude extract (Ph.Cr), its subsequent fractions: n-hexane (Ph.Hex), chloroform (Ph.Chf), ethyl acetate (Ph.EtAc), n-Butanol (Ph.Bt), aqueous (Ph.Aq) and saponins (Ph.Sp) were evaluated for 1,1-diphenyl,2-picrylhydrazyl (DPPH), 2,2-azinobis[3-ethylbenzthiazoline]-6-sulfonic acid (ABTS) free radical scavenging potential. Further, acetylcholinesterase (AChE) & butyrylcholinesterase (BChE) inhibitory activities were performed using Ellman's assay. Moreover, total phenolic contents of plant extracts were determined and expressed in mg of gallic acid equivalent per gram of dry sample (mg GAE/g dry weight). Results Among different fractions, Ph.Cr (90.82), Ph.Chf (178.16), Ph.EtAc (203.44) and Ph.Bt (153.61) exhibited high phenolic contents. All fractions showed concentration dependent DPPH scavenging activity, with Ph.EtAc 71.33% (IC50 15 μg/ml), Ph.Bt 71.40% (IC50 3 μg/ml) and Ph.Sp 71.40% (IC50 35 μg/ml) were most potent. The plant extracts exhibited high ABTS scavenging ability i.e. Ph.Bt (91.03%), Ph.EtAc (90.56%), Ph.Sp (90.84%), Ph.Aq (90.56%) with IC50 < 0.01 μg/ml. All fractions showed moderate to high AChE inhibitory activity as; Ph.Cr, 86.87% (IC50 330 μg/ml), Ph.Hex, 87.49% (IC50 35 μg/ml), Ph.Chf, 84.76% (IC50 55 μg/ml), Ph.Sp, 87.58% (IC50 108 μg/ml) and Ph.EtAc 79.95% (IC50 310 μg/ml) at 1 mg/ml). Furthermore the BChE inhibitory activity was most prominent in Ph.Hex 90.30% (IC50 40 μg/ml), Ph.Chf 85.94% (IC50 215 μg/ml), Ph.Aq 87.62% (IC50 3 μg/ml) and Ph.EtAc 81.01% (IC50 395 μg/ml) fractions. Conclusions In this study, for the first time, we determined phenolic contents, isolated crude saponins, investigated antioxidant and anticholinestrase potential of P. hydropiper extracts. The results indicate that P. hydropiper is enriched with potent bioactive compounds and warrant further investigation by isolation and structural elucidation to find novel and affordable compounds for the treatment of various neurological disorders. PMID:24884823

Phenolic contents, antioxidant and anticholinesterase potentials of crude extract, subsequent fractions and crude saponins from Polygonum hydropiper L.

PubMed

Ayaz, Muhammad; Junaid, Muhammad; Ahmed, Jawad; Ullah, Farhat; Sadiq, Abdul; Ahmad, Sajjad; Imran, Muhammad

2014-05-03

We investigated Polygonum hydropiper L. (P. hydropiper) for phenolic contents, antioxidant, anticholinesterase activities, in an attempt to rationalize its use in neurological disorders. Plant crude extract (Ph.Cr), its subsequent fractions: n-hexane (Ph.Hex), chloroform (Ph.Chf), ethyl acetate (Ph.EtAc), n-Butanol (Ph.Bt), aqueous (Ph.Aq) and saponins (Ph.Sp) were evaluated for 1,1-diphenyl,2-picrylhydrazyl (DPPH), 2,2-azinobis[3-ethylbenzthiazoline]-6-sulfonic acid (ABTS) free radical scavenging potential. Further, acetylcholinesterase (AChE) & butyrylcholinesterase (BChE) inhibitory activities were performed using Ellman's assay. Moreover, total phenolic contents of plant extracts were determined and expressed in mg of gallic acid equivalent per gram of dry sample (mg GAE/g dry weight). Among different fractions, Ph.Cr (90.82), Ph.Chf (178.16), Ph.EtAc (203.44) and Ph.Bt (153.61) exhibited high phenolic contents. All fractions showed concentration dependent DPPH scavenging activity, with Ph.EtAc 71.33% (IC50 15 μg/ml), Ph.Bt 71.40% (IC50 3 μg/ml) and Ph.Sp 71.40% (IC50 35 μg/ml) were most potent. The plant extracts exhibited high ABTS scavenging ability i.e. Ph.Bt (91.03%), Ph.EtAc (90.56%), Ph.Sp (90.84%), Ph.Aq (90.56%) with IC50<0.01 μg/ml. All fractions showed moderate to high AChE inhibitory activity as; Ph.Cr, 86.87% (IC50 330 μg/ml), Ph.Hex, 87.49% (IC50 35 μg/ml), Ph.Chf, 84.76% (IC50 55 μg/ml), Ph.Sp, 87.58% (IC50 108 μg/ml) and Ph.EtAc 79.95% (IC50 310 μg/ml) at 1 mg/ml). Furthermore the BChE inhibitory activity was most prominent in Ph.Hex 90.30% (IC50 40 μg/ml), Ph.Chf 85.94% (IC50 215 μg/ml), Ph.Aq 87.62% (IC50 3 μg/ml) and Ph.EtAc 81.01% (IC50 395 μg/ml) fractions. In this study, for the first time, we determined phenolic contents, isolated crude saponins, investigated antioxidant and anticholinestrase potential of P. hydropiper extracts. The results indicate that P. hydropiper is enriched with potent bioactive compounds and warrant further investigation by isolation and structural elucidation to find novel and affordable compounds for the treatment of various neurological disorders.

Suicide Inhibitors of Reverse Transcriptase in the Therapy of AIDS and Other Retroviruses

DTIC Science & Technology

1990-07-01

I and 10 nanonolar) and compared to the E . Coli recombinant HIV-RT (Kindly donated by Dr. Steven Hughes Fort Detrick M.D.) and the wild type HIV-RT...Both the wild type and E . Coli HIV-RT’s were resistant to PFA showing essentially no inhibition at the lOnM level. Previous studies have shown that...10 nanomolar PFA. j, Sentivitv of Recombinant HIV-Reverse Transcriotase to Foscarnet. RECOMBINANT HIV RT ( E . COLI) + FOSCARNET 350001R 300000 PFA .001

Evaluation of Cytokine Synthesis in Human Whole Blood by Enzyme Linked Immunoassay (ELISA), Reverse Transcriptase Polymerase Chain Reaction (RT-PCR), and Flow Cytometry

DTIC Science & Technology

2007-05-08

deoxynucleotide triphosphates, from Sigma. Sequences for glyceraldehyde-3-phosphate dehydrogenase ( G3PDH ), IL-8,and TNF-a were amplified with primer...This was accomplished by normalizing all samples to the mRNA for the moderately expressed housekeeping function glyceraldehyde-3 -phosphate...without and with isolation of cells before reverse transcription and PCR. G3PDH mRNA target amplifies at 983 base pairs. The 630 base pair band is the

First report of Cocksfoot mottle virus infecting wheat (Triticum aestivum) in Ohio

USDA-ARS?s Scientific Manuscript database

Cocksfoot mottle virus (CfMV) was discovered in Ohio wheat during a 2016 field survey utilizing RNA-Seq to identify virus-like sequences. Virus sequences were confirmed by reverse transcriptase-polymerase chain reaction (RT-PCR) and Sanger sequencing, and CfMV was transmitted to orchardgrass and pas...

RNA Extraction Methods for Reverse Transcriptase Real-Time PCR and Microarray Analysis of Cryptosporidium and Toxoplasma gondii Oocysts

EPA Science Inventory

The ability of infectious oocyst forms of Toxoplasma gondii and Cryptosporidium spp. to resist disinfection treatments and cause disease may have significant public health implications. Currently, little is known about oocyst-specific factors involved during host cell invasion p...

Problem-Solving Test: Expression Cloning of the Erythropoietin Receptor

ERIC Educational Resources Information Center

Szeberenyi, Jozsef

2008-01-01

Terms to be familiar with before you start to solve the test: cytokines, cytokine receptors, cDNA library, cDNA synthesis, poly(A)[superscript +] RNA, primer, template, reverse transcriptase, restriction endonucleases, cohesive ends, expression vector, promoter, Shine-Dalgarno sequence, poly(A) signal, DNA helicase, DNA ligase, topoisomerases,…

Isolation and characterization of an AGAMOUS homolog from Fraxinus pennsylvanica

Treesearch

Ningxia Du; Paula M. Pijut

2010-01-01

An AGAMOUS homolog (FpAG) was isolated from green ash (Fraxinus pennsylvanica) using a reverse transcriptase polymerase chain reaction method. Southern blot analysis indicated that FpAG was present as a single-copy sequence in the genome of green ash. RNA accumulated in the reproductive tissues (female...

In-vitro Cell Culture and Real-time Reverse Transcriptase PCR-based Assays to Detect Infective Toxoplas gondii Oocysts

EPA Science Inventory

Toxoplasma gondii is an obligate intracellular, apicomplexan parasite that infects humans. It is ubiquitous in nature and seroprevalence in the United States and in Europe ranges from 25->70%. Although typically associated with causing foodborne outbreaks, recent studies in Canad...

Quantification of HTLV-1 reverse transcriptase activity in ATL patients treated with zidovudine and interferon-α.

PubMed

Macchi, Beatrice; Balestrieri, Emanuela; Frezza, Caterina; Grelli, Sandro; Valletta, Elena; Marçais, Ambroise; Marino-Merlo, Francesca; Turpin, Jocelyn; Bangham, Charles R; Hermine, Olivier; Mastino, Antonio; Bazarbachi, Ali

2017-05-09

The therapeutic efficacy of the AZT and IFN combination in ATL presumably reflects the inhibition of RT-related functions.HTLV-1-RT activity from short-term cultured PBMCs may represent a predictive correlate of clinical response to AZT/IFN in ATL patients.

Variability in P-Glycoprotein Inhibitory Potency (IC50) Using Various in Vitro Experimental Systems: Implications for Universal Digoxin Drug-Drug Interaction Risk Assessment Decision Criteria

PubMed Central

Bentz, Joe; O’Connor, Michael P.; Bednarczyk, Dallas; Coleman, JoAnn; Lee, Caroline; Palm, Johan; Pak, Y. Anne; Perloff, Elke S.; Reyner, Eric; Balimane, Praveen; Brännström, Marie; Chu, Xiaoyan; Funk, Christoph; Guo, Ailan; Hanna, Imad; Herédi-Szabó, Krisztina; Hillgren, Kate; Li, Libin; Hollnack-Pusch, Evelyn; Jamei, Masoud; Lin, Xuena; Mason, Andrew K.; Neuhoff, Sibylle; Patel, Aarti; Podila, Lalitha; Plise, Emile; Rajaraman, Ganesh; Salphati, Laurent; Sands, Eric; Taub, Mitchell E.; Taur, Jan-Shiang; Weitz, Dietmar; Wortelboer, Heleen M.; Xia, Cindy Q.; Xiao, Guangqing; Yabut, Jocelyn; Yamagata, Tetsuo; Zhang, Lei

2013-01-01

A P-glycoprotein (P-gp) IC50 working group was established with 23 participating pharmaceutical and contract research laboratories and one academic institution to assess interlaboratory variability in P-gp IC50 determinations. Each laboratory followed its in-house protocol to determine in vitro IC50 values for 16 inhibitors using four different test systems: human colon adenocarcinoma cells (Caco-2; eleven laboratories), Madin-Darby canine kidney cells transfected with MDR1 cDNA (MDCKII-MDR1; six laboratories), and Lilly Laboratories Cells—Porcine Kidney Nr. 1 cells transfected with MDR1 cDNA (LLC-PK1-MDR1; four laboratories), and membrane vesicles containing human P-glycoprotein (P-gp; five laboratories). For cell models, various equations to calculate remaining transport activity (e.g., efflux ratio, unidirectional flux, net-secretory-flux) were also evaluated. The difference in IC50 values for each of the inhibitors across all test systems and equations ranged from a minimum of 20- and 24-fold between lowest and highest IC50 values for sertraline and isradipine, to a maximum of 407- and 796-fold for telmisartan and verapamil, respectively. For telmisartan and verapamil, variability was greatly influenced by data from one laboratory in each case. Excluding these two data sets brings the range in IC50 values for telmisartan and verapamil down to 69- and 159-fold. The efflux ratio-based equation generally resulted in severalfold lower IC50 values compared with unidirectional or net-secretory-flux equations. Statistical analysis indicated that variability in IC50 values was mainly due to interlaboratory variability, rather than an implicit systematic difference between test systems. Potential reasons for variability are discussed and the simplest, most robust experimental design for P-gp IC50 determination proposed. The impact of these findings on drug-drug interaction risk assessment is discussed in the companion article (Ellens et al., 2013) and recommendations are provided. PMID:23620485

Brief Report: Long-Term (96-Week) Efficacy and Safety After Switching From Tenofovir Disoproxil Fumarate to Tenofovir Alafenamide in HIV-Infected, Virologically Suppressed Adults

PubMed Central

Raffi, François; Orkin, Chloe; Clarke, Amanda; Slama, Laurence; Gallant, Joel; Daar, Eric; Henry, Keith; Santana-Bagur, Jorge; Stein, David K.; Bellos, Nicholaos; Scarsella, Anthony; Yan, Mingjin; Abram, Michael E.; Cheng, Andrew

2017-01-01

Abstract: In a double-blind, phase 3 trial, 663 HIV-infected, virologically suppressed adults were randomized to switch to tenofovir alafenamide (TAF; n = 333) vs. remain on tenofovir disoproxil fumarate (TDF; n = 330), each coformulated with emtricitabine (FTC), while continuing their third agent (boosted protease inhibitor or unboosted third agent). At week 96, 88.6% on FTC/TAF and 89.1% on FTC/TDF had HIV-1 RNA <50 copies per milliliter [adjusted difference −0.5% (95% confidence interval: −5.3 to 4.4%)]. Proteinuria, albuminuria, proximal renal tubular function, and bone mineral density improved after switching to TAF- from TDF-containing regimens. These longer-term data support FTC/TAF as a safe, well-tolerated, and durable nucleotide reverse transcriptase inhibitor backbone. PMID:28272164

Identification and characterization of jute LTR retrotransposons:

PubMed Central

Ahmed, Salim; Shafiuddin, MD; Azam, Muhammad Shafiul; Islam, Md. Shahidul; Ghosh, Ajit

2011-01-01

Long Terminal Repeat (LTR) retrotransposons constitute a significant part of eukaryotic genomes and play an important role in genome evolution especially in plants. Jute is an important fiber crop with a large genome of 1,250 Mbps. This genome is still mostly unexplored. In this study we aimed at identifying and characterizing the LTR retrotransposons of jute with a view to understanding the jute genome better. In this study, the Reverse Transcriptase domain of Ty1-copia and Ty3-gypsy LTR retrotransposons of jute were amplified by degenerate primers and their expressions were examined by reverse transcription PCR. Copy numbers of reverse transcriptase (RT) genes of Ty1-copia and Ty3-gypsy elements were determined by dot blot analysis. Sequence analysis revealed higher heterogeneity among Ty1-copia retrotransposons than Ty3-gypsy and clustered each of them in three groups. Copy number of RT genes in Ty1-copia was found to be higher than that of Ty3-gypsy elements from dot blot hybridization. Cumulatively Ty1-copia and Ty3-gypsy may constitute around 19% of the jute genome where two groups of Ty1-copia were found to be transcriptionally active. Since the LTR retrotransposons constitute a large portion of jute genome, these findings imply the importance of these elements in the evolution of jute genome. PMID:22016842

Active methamphetamine use is associated with transmitted drug resistance to non-nucleoside reverse transcriptase inhibitors in individuals with HIV infection of unknown duration.

PubMed

Cachay, Edward R; Moini, Niousha; Kosakovsky Pond, Sergei L; Pesano, Rick; Lie, Yolanda S; Aiem, Heidi; Butler, David M; Letendre, Scott; Mathews, Wm Christopher; Smith, Davey M

2007-01-01

Frequent methamphetamine use among recently HIV infected individuals is associated with transmitted drug resistance (TDR) to non-nucleoside reverse transcriptase inhibitors (NNRTI); however, the reversion time of TDR to drug susceptible HIV may exceed 3 years. We assessed whether recreational substance use is associated with detectable TDR among individuals newly diagnosed with HIV infection of unknown duration. Cross-sectional analysis. Subjects were enrolled at the University California, San Diego Early Intervention Program. Demographic, clinical and substance use data were collected using structured interviews. Genotypic resistance testing was performed using GeneSeq, Monogram Biosciences. We analyzed the association between substance use and TDR using bivariate analyses and the corresponding transmission networks using phylogenetic models. Between April 2004 and July 2006, 115 individuals with genotype data were enrolled. The prevalence of alcohol, marijuana and methamphetamine use were 98%, 71% and 64% respectively. Only active methamphetamine use in the 30 days prior to HIV diagnosis was independently associated with TDR to NNRTI (OR: 6.6; p=0.002). Despite not knowing the duration of their HIV infection, individuals reporting active methamphetamine use in the 30 days prior to HIV diagnosis are at an increased risk of having HIV strains that are resistant to NNRTI.

A novel application of t-statistics to objectively assess the quality of IC50 fits for P-glycoprotein and other transporters.

PubMed

O'Connor, Michael; Lee, Caroline; Ellens, Harma; Bentz, Joe

2015-02-01

Current USFDA and EMA guidance for drug transporter interactions is dependent on IC50 measurements as these are utilized in determining whether a clinical interaction study is warranted. It is therefore important not only to standardize transport inhibition assay systems but also to develop uniform statistical criteria with associated probability statements for generation of robust IC50 values, which can be easily adopted across the industry. The current work provides a quantitative examination of critical factors affecting the quality of IC50 fits for P-gp inhibition through simulations of perfect data with randomly added error as commonly observed in the large data set collected by the P-gp IC50 initiative. The types of errors simulated were (1) variability in replicate measures of transport activity; (2) transformations of error-contaminated transport activity data prior to IC50 fitting (such as performed when determining an IC50 for inhibition of P-gp based on efflux ratio); and (3) the lack of well defined "no inhibition" and "complete inhibition" plateaus. The effect of the algorithm used in fitting the inhibition curve (e.g., two or three parameter fits) was also investigated. These simulations provide strong quantitative support for the recommendations provided in Bentz et al. (2013) for the determination of IC50 values for P-gp and demonstrate the adverse effect of data transformation prior to fitting. Furthermore, the simulations validate uniform statistical criteria for robust IC50 fits in general, which can be easily implemented across the industry. A calibration of the t-statistic is provided through calculation of confidence intervals associated with the t-statistic.

A novel application of t-statistics to objectively assess the quality of IC50 fits for P-glycoprotein and other transporters

PubMed Central

O'Connor, Michael; Lee, Caroline; Ellens, Harma; Bentz, Joe

2015-01-01

Current USFDA and EMA guidance for drug transporter interactions is dependent on IC50 measurements as these are utilized in determining whether a clinical interaction study is warranted. It is therefore important not only to standardize transport inhibition assay systems but also to develop uniform statistical criteria with associated probability statements for generation of robust IC50 values, which can be easily adopted across the industry. The current work provides a quantitative examination of critical factors affecting the quality of IC50 fits for P-gp inhibition through simulations of perfect data with randomly added error as commonly observed in the large data set collected by the P-gp IC50 initiative. The types of errors simulated were (1) variability in replicate measures of transport activity; (2) transformations of error-contaminated transport activity data prior to IC50 fitting (such as performed when determining an IC50 for inhibition of P-gp based on efflux ratio); and (3) the lack of well defined “no inhibition” and “complete inhibition” plateaus. The effect of the algorithm used in fitting the inhibition curve (e.g., two or three parameter fits) was also investigated. These simulations provide strong quantitative support for the recommendations provided in Bentz et al. (2013) for the determination of IC50 values for P-gp and demonstrate the adverse effect of data transformation prior to fitting. Furthermore, the simulations validate uniform statistical criteria for robust IC50 fits in general, which can be easily implemented across the industry. A calibration of the t-statistic is provided through calculation of confidence intervals associated with the t-statistic. PMID:25692007

GLC-3: a novel fipronil and BIDN-sensitive, but picrotoxinin-insensitive, L-glutamate-gated chloride channel subunit from Caenorhabditis elegans

PubMed Central

Horoszok, Lucy; Raymond, Valérie; Sattelle, David B; Wolstenholme, Adrian J

2001-01-01

We report the cloning and expression of a novel Caenorhabditis elegans polypeptide, GLC-3, with high sequence identity to previously cloned L-glutamate-gated chloride channel subunits from nematodes and insects. Expression of glc-3 cRNA in Xenopus oocytes resulted in the formation of homo-oligomeric L-glutamate-gated chloride channels with robust and rapidly desensitizing currents, an EC50 of 1.9±0.03 mM and a Hill coefficient of 1.5±0.1. GABA, glycine, histamine and NMDA all failed to activate the GLC-3 homo-oligomer at concentrations of 1 mM. The anthelminthic, ivermectin, directly and irreversibly activated the L-glutamate-gated channel with an EC50 of 0.4±0.02 μM. The GLC-3 channels were selective for chloride ions, as shown by the shift in the reversal potential for L-glutamate-gated currents after the reduction of external Cl− from 107.6 to 62.5 mM. Picrotoxinin failed to inhibit L-glutamate agonist responses at concentrations up to 1 mM. The polycyclic dinitrile, 3,3-bis-trifluoromethyl-bicyclo[2,2,1]heptane-2,2-dicarbonitrile (BIDN), completely blocked L-glutamate-induced chloride currents recorded from oocytes expressing GLC-3 with an IC50 of 0.2±0.07 μM. The phenylpyrazole insecticide, fipronil, reversibly inhibited L-glutamate-gated currents recorded from the GLC-3 receptor with an IC50 of 11.5±0.11 μM. In this study, we detail the unusual antagonist pharmacology of a new GluCl subunit from C. elegans. Unlike all other native and recombinant nematode GluCl reported to date, the GLC-3 receptor is insensitive to picrotoxinin, but is sensitive to two other channel blockers, BIDN and fipronil. Further study of this receptor may provide insights into the molecular basis of non-competitive antagonism by these compounds. PMID:11250875

Inhibitory Effects of Amorphigenin on the Mitochondrial Complex I of Culex pipiens pallens Coquillett (Diptera: Culicidae)

PubMed Central

Ji, Mingshan; Liang, Yaping; Gu, Zumin; Li, Xiuwei

2015-01-01

Previous studies in our laboratory found that the extract from seeds of Amorpha fruticosa in the Leguminosae family had lethal effects against mosquito larvae, and an insecticidal compound amorphigenin was isolated. In this study, the inhibitory effects of amorphigenin against the mitochondrial complex I of Culex pipiens pallens (Diptera: Culicidae) were investigated and compared with that of rotenone. The results showed that amorphigenin and rotenone can decrease the mitochondrial complex I activity both in vivo and in vitro as the in vivo IC50 values (the inhibitor concentrations leading to 50% of the enzyme activity lost) were determined to be 2.4329 and 2.5232 μmol/L, respectively, while the in vitro IC50 values were 2.8592 and 3.1375 μmol/L, respectively. Both amorphigenin and rotenone were shown to be reversible and mixed-I type inhibitors of the mitochondrial complex I of Cx. pipiens pallens, indicating that amorphigenin and rotenone inhibited the enzyme activity not only by binding with the free enzyme but also with the enzyme-substrate complex, and the values of KI and KIS for amorphigenin were determined to be 20.58 and 87.55 μM, respectively, while the values for rotenone were 14.04 and 69.23 μM, respectively. PMID:26307964

Angiotensin I-Converting Enzyme Inhibitor Derived from Cross-Linked Oyster Protein

PubMed Central

Xie, Cheng-Liang; Kim, Jin-Soo; Ha, Jong-Myung; Choung, Se-Young

2014-01-01

Following cross-linking by microbial transglutaminase, modified oyster proteins were hydrolyzed to improve inhibitory activity against angiotensin-converting enzyme (ACE) inhibitory activity with the use of a single protease, or a combination of six proteases. The oyster hydrolysate with the lowest 50% ACE inhibitory concentration (IC50) of 0.40 mg/mL was obtained by two-step hydrolysis of the cross-linked oyster protein using Protamex and Neutrase. Five ACE inhibitory peptides were purified from the oyster hydrolysate using a multistep chromatographic procedure comprised of ion-exchange, size exclusion, and reversed-phase liquid chromatography. Their sequences were identified as TAY, VK, KY, FYN, and YA, using automated Edman degradation and mass spectrometry. These peptides were synthesized, and their IC50 values were measured to be 16.7, 29.0, 51.5, 68.2, and 93.9 μM, respectively. Toxicity of the peptides on the HepG2 cell line was not detected. The oyster hydrolysate also significantly decreased the systolic blood pressure of spontaneously hypertensive rats (SHR). The antihypertensive effect of the oyster hydrolysate on SHR was rapid and long-lasting, compared to commercially obtained sardine hydrolysate. These results suggest that the oyster hydrolysate could be a source of effective nutraceuticals against hypertension. PMID:25140307

Report: screening of selected medicinal plants for their enzyme inhibitory potential - a validation of their ethnopharmacological uses.

PubMed

Khuda, Fazli; Iqbal, Zafar; Khan, Ayub; Zakiullah; Shah, Yasar; Khan, Abad

2014-05-01

In present study four medicinal plants namely Valeriana wallichii, Xanthium strumarium, Achyranthes aspera and Duchesnea indica belonging to different families were collected in Khyber Pakhtunkhwa province and crude extract and subsequent fractions were analyzed for their inhibitory potential against acetylcholinesterase, butyrylcholinesterase and α-glucosidase enzymes. Valeriana wallichii, Xanthium strumarium and Achyranthes aspera were significantly active against cholinesterases. Chloroform and ethylacetate fractions of Valeriana wallichii exhibited significant activity against acetylcholinesterase (IC50: 61μg/ml) and butyrylcholinesterase enzymes (IC50: 58μg/ml), respectively. Similarly ethylacetate fraction of Achyranthes aspera showed significant activity against acetylcholinesterase (IC50: 61 μg/ml) and butyrylcholinesterase enzymes (IC50: 61 μg/ml), respectively. In case of α-glucosidase enzyme, the chloroform fraction of Xanthium strumarium exhibited significant inhibitory activity (IC50: 72 μg/ml) as compared to the standard compound acarbose (IC50: 483 μg/ml). Duchesnea indica showed no such activities.

2,4,6-Trichlorophenylhydrazine Schiff bases as DPPH radical and super oxide anion scavengers.

PubMed

Khan, Khalid Mohammed; Shah, Zarbad; Ahmad, Viqar Uddin; Khan, Momin; Taha, Muhammad; Rahim, Fazal; Ali, Sajjad; Ambreen, Nida; Perveen, Shahnaz; Choudhary, M Iqbal; Voelter, Wolfgang

2012-05-01

Syntheses of thirty 2,4,6-trichlorophenylhydrazine Schiff bases 1-30 were carried out and evaluated for their in vitro DPPH radical and super oxide anion scavenging activities. Compounds 1-30 have shown a varying degree of DPPH radical scavenging activity and their IC50 values range between 4.05-369.30 µM. The compounds 17, 28, 18, 14, 8, 15, 12, 2, 29, and 7 exhibited IC50 values ranging between 4.05±0.06-24.42±0.86 µM which are superior to standard n-propylgallate (IC50=30.12±0.27 µM). Selected compounds have shown a varying degree of superoxide anion radical scavenger activity and their IC50 values range between 91.23-406.90 µM. The compounds 28, 8, 17, 15, and 14, showed IC50 values between 91.23±1.2-105.31±2.29 µM which are superior to standard n-propylgallate (IC50=106.34±1.6 µM).

Integration of maternal genome into the neonate genome through breast milk mRNA transcripts and reverse transcriptase.

PubMed

Irmak, M Kemal; Oztas, Yesim; Oztas, Emin

2012-06-07

Human milk samples contain microvesicles similar to the retroviruses. These microvesicles contain mRNA transcripts and possess reverse transcriptase activity. They contain about 14,000 transcripts representing the milk transcriptome. Microvesicles are also enriched with proteins related to "caveolar-mediated endocytosis signaling" pathway. It has recently been reported that microvesicles could be transferred to other cells by endocytosis and their RNA content can be translated and be functional in their new location. A significant percentage of the mammalian genome appears to be the product of reverse transcription, containing sequences whose characteristics point to RNA as a template precursor. These are mobile elements that move by way of transposition and are called retrotransposons. We thought that retrotransposons may stem from about 14,000 transcriptome of breast milk microvesicles, and reviewed the literature.The enhanced acceptance of maternal allografts in children who were breast-fed and tolerance to the maternal MHC antigens after breastfeeding may stem from RNAs of the breast milk microvesicles that can be taken up by the breastfed infant and receiving maternal genomic information. We conclude that milk microvesicles may transfer genetic signals from mother to neonate during breastfeeding. Moreover, transfer of wild type RNA from a healthy wet-nurse to the suckling neonate through the milk microvesicles and its subsequent reverse transcription and integration into the neonate genome could result in permanent correction of the clinical manifestations in genetic diseases.

The Reverse Transcription Inhibitor Abacavir Shows Anticancer Activity in Prostate Cancer Cell Lines

PubMed Central

Molinari, Agnese; Parisi, Chiara; Bozzuto, Giuseppina; Toccacieli, Laura; Formisano, Giuseppe; De Orsi, Daniela; Paradisi, Silvia; Grober, OlÌ Maria Victoria; Ravo, Maria; Weisz, Alessandro; Arcieri, Romano; Vella, Stefano; Gaudi, Simona

2010-01-01

Background Transposable Elements (TEs) comprise nearly 45% of the entire genome and are part of sophisticated regulatory network systems that control developmental processes in normal and pathological conditions. The retroviral/retrotransposon gene machinery consists mainly of Long Interspersed Nuclear Elements (LINEs-1) and Human Endogenous Retroviruses (HERVs) that code for their own endogenous reverse transcriptase (RT). Interestingly, RT is typically expressed at high levels in cancer cells. Recent studies report that RT inhibition by non-nucleoside reverse transcriptase inhibitors (NNRTIs) induces growth arrest and cell differentiation in vitro and antagonizes growth of human tumors in animal model. In the present study we analyze the anticancer activity of Abacavir (ABC), a nucleoside reverse transcription inhibitor (NRTI), on PC3 and LNCaP prostate cancer cell lines. Principal Findings ABC significantly reduces cell growth, migration and invasion processes, considerably slows S phase progression, induces senescence and cell death in prostate cancer cells. Consistent with these observations, microarray analysis on PC3 cells shows that ABC induces specific and dose-dependent changes in gene expression, involving multiple cellular pathways. Notably, by quantitative Real-Time PCR we found that LINE-1 ORF1 and ORF2 mRNA levels were significantly up-regulated by ABC treatment. Conclusions Our results demonstrate the potential of ABC as anticancer agent able to induce antiproliferative activity and trigger senescence in prostate cancer cells. Noteworthy, we show that ABC elicits up-regulation of LINE-1 expression, suggesting the involvement of these elements in the observed cellular modifications. PMID:21151977

Integration of maternal genome into the neonate genome through breast milk mRNA transcripts and reverse transcriptase

PubMed Central

2012-01-01

Human milk samples contain microvesicles similar to the retroviruses. These microvesicles contain mRNA transcripts and possess reverse transcriptase activity. They contain about 14,000 transcripts representing the milk transcriptome. Microvesicles are also enriched with proteins related to “caveolar-mediated endocytosis signaling” pathway. It has recently been reported that microvesicles could be transferred to other cells by endocytosis and their RNA content can be translated and be functional in their new location. A significant percentage of the mammalian genome appears to be the product of reverse transcription, containing sequences whose characteristics point to RNA as a template precursor. These are mobile elements that move by way of transposition and are called retrotransposons. We thought that retrotransposons may stem from about 14,000 transcriptome of breast milk microvesicles, and reviewed the literature. The enhanced acceptance of maternal allografts in children who were breast-fed and tolerance to the maternal MHC antigens after breastfeeding may stem from RNAs of the breast milk microvesicles that can be taken up by the breastfed infant and receiving maternal genomic information. We conclude that milk microvesicles may transfer genetic signals from mother to neonate during breastfeeding. Moreover, transfer of wild type RNA from a healthy wet-nurse to the suckling neonate through the milk microvesicles and its subsequent reverse transcription and integration into the neonate genome could result in permanent correction of the clinical manifestations in genetic diseases. PMID:22676860

Arm-specific cleavage and mutation during reverse transcription of 2΄,5΄-branched RNA by Moloney murine leukemia virus reverse transcriptase

PubMed Central

Döring, Jessica

2017-01-01

Abstract Branchpoint nucleotides of intron lariats induce pausing of DNA synthesis by reverse transcriptases (RTs), but it is not known yet how they direct RT RNase H activity on branched RNA (bRNA). Here, we report the effects of the two arms of bRNA on branchpoint-directed RNA cleavage and mutation produced by Moloney murine leukemia virus (M-MLV) RT during DNA polymerization. We constructed a long-chained bRNA template by splinted-ligation. The bRNA oligonucleotide is chimeric and contains DNA to identify RNA cleavage products by probe hybridization. Unique sequences surrounding the branchpoint facilitate monitoring of bRNA purification by terminal-restriction fragment length polymorphism analysis. We evaluate the M-MLV RT-generated cleavage and mutational patterns. We find that cleavage of bRNA and misprocessing of the branched nucleotide proceed arm-specifically. Bypass of the branchpoint from the 2΄-arm causes single-mismatch errors, whereas bypass from the 3΄-arm leads to deletion mutations. The non-template arm is cleaved when reverse transcription is primed from the 3΄-arm but not from the 2΄-arm. This suggests that RTs flip ∼180° at branchpoints and RNases H cleave the non-template arm depending on its accessibility. Our observed interplay between M-MLV RT and bRNA would be compatible with a bRNA-mediated control of retroviral and related retrotransposon replication. PMID:28160599

Inhibition of P-glycoprotein in Caco-2 cells: effects of herbal remedies frequently used by cancer patients.

PubMed

Engdal, S; Nilsen, O G

2008-06-01

1. The herbal products Natto K2, Agaricus, mistletoe, noni juice, green tea and garlic were investigated for in vitro inhibitory potential on P-glycoprotein (P-gp)-mediated transport of digoxin (30 nM) in differentiated and polarized Caco-2 cells. 2. Satisfactory cell functionality was demonstrated through measurements of assay linearity, transepithelial electric resistance (TEER), cytotoxicity, mannitol permeability, and inclusion of the positive inhibition control verapamil. 3. The most potent inhibitors of the net digoxin flux (IC(50)) were mistletoe > Natto K2 > Agaricus > green tea (0.022, 0.62, 3.81, >4.5 mg ml(-1), respectively). Mistletoe also showed the lowest IC(25) value, close to that obtained by verapamil (1.0 and 0.5 microg ml(-1), respectively). The IC(50)/IC(25) ratio was found to be a good parameter for the determination of inhibition profiles. Garlic and noni juice were classified as non-inhibitors. 4. This study shows that mistletoe, Natto K2, Agaricus and green tea inhibit P-gp in vitro. Special attention should be paid to mistletoe due to very low IC(50) and IC(25) values and to Natto K2 due to a low IC(50) value and a low IC(50)/IC(25) ratio.

A virtual screening method for inhibitory peptides of Angiotensin I-converting enzyme.

PubMed

Wu, Hongxi; Liu, Yalan; Guo, Mingrong; Xie, Jingli; Jiang, XiaMin

2014-09-01

Natural small peptides from foods have been proven to be efficient inhibitors of Angiotensin I-converting enzyme (ACE) for the regulation of blood pressure. The traditional ACE inhibitory peptides screening method is both time consuming and money costing, to the contrary, virtual screening method by computation can break these limitations. We establish a virtual screening method to obtain ACE inhibitory peptides with the help of Libdock module of Discovery Studio 3.5 software. A significant relationship between Libdock score and experimental IC(50) was found, Libdock score = 10.063 log(1/IC(50)) + 68.08 (R(2) = 0.62). The credibility of the relationship was confirmed by testing the coincidence of the estimated log(1/IC(50)) and measured log(1/IC(50)) (IC(50) is 50% inhibitory concentration toward ACE, in μmol/L) of 5 synthetic ACE inhibitory peptides, which was virtual hydrolyzed and screened from a kind of seafood, Phascolosoma esculenta. Accordingly, Libdock method is a valid IC(50) estimation tool and virtual screening method for small ACE inhibitory peptides. © 2014 Institute of Food Technologists®

Antioxidant Effect of Berberine and its Phenolic Derivatives Against Human Fibrosarcoma Cells.

PubMed

Pongkittiphan, Veerachai; Chavasiri, Warinthorn; Supabphol, Roongtawan

2015-01-01

Berberine (B1), isolated from stems of Coscinium fenestratum (Goetgh.) Colebr, was used as a principle structure to synthesize three phenolic derivatives: berberrubine (B2) with a single phenolic group, berberrubine chloride (B3) as a chloride counter ion derivative, and 2,3,9,10-tetra-hydroxyberberine chloride (B4) with four phenolic groups, to investigate their direct and indirect antioxidant activities. For DPPH assay, compounds B4, B3, and B2 showed good direct antioxidant activity (IC50 values=10.7±1.76, 55.2±2.24, and 87.4±6.65 μM, respectively) whereas the IC50 value of berberine was higher than 500 μM. Moreover, compound B4 exhibited a better DPPH scavenging activity than BHT as a standard antioxidant (IC50=72.7±7.22 μM) due to the ortho position of hydroxyl groups and its capacity to undergo intramolecular hydrogen bonding. For cytotoxicity assay against human fibrosarcoma cells (HT1080) using MTT reagent, the sequence of IC50 value at 7-day treatment stated that B1

Antiproliferative activities and phenolic acid content of water and ethanolic extracts of the powdered formula of Houttuynia cordata Thunb. fermented broth and Phyllanthus emblica Linn. fruit.

PubMed

Kumnerdkhonkaen, Piyawan; Saenglee, Somprasong; Asgar, Md Ali; Senawong, Gulsiri; Khongsukwiwat, Kanoknan; Senawong, Thanaset

2018-04-11

Houttuynia cordata Thunb. and Phyllanthus emblica Linn. are native plants with medicinal and nutritive significance in Asia. The present study was aimed at evaluating antiproliferative effects on human cancer cell lines and identifying the phenolic acid composition of water and ethanolic extracts of the powdered formula of H. cordata fermented broth and P. emblica fruit. Anticancer activity of the extracts was evaluated against HeLa, HT29, HCT116, MCF7 and Jurkat cells using an MTT assay and flow cytometric analysis of apoptosis induction and cell cycle arrest. Reverse phase HPLC was exploited for identification and quantification of some phenolic acids. MTT assay showed that both water and ethanolic extracts significantly decreased the viability of cancer cells in a dose- and time-dependent fashion. Based on the IC 50 values, ethanolic extract (IC 50 values = 0.12-0.65 mg/mL) was more cytotoxic than water extract (IC 50 values = 0.22-0.85 mg/mL) and Jurkat cells were the most sensitive to both extracts (IC 50 values = 0.12-0.69 mg/mL). The underlying mechanism for antiproliferative activity was apoptosis induction, especially in HT29, HCT116, MCF7 and Jurkat cells. HT29 cells were the most sensitive to extract-induced apoptosis. Ethanolic extract was more effective at inducing apoptosis than water extract. Moreover, cell cycle arrest was found to be another mechanism behind growth inhibition in Jurkat and HCT116 cells. However, these extracts were relatively less toxic to non-cancer Vero cells. HPLC analysis demonstrated that the powder mix extracts contained seven identified phenolic acids namely gallic, p-hydroxybenzoic, vanillic, syringic, p-coumaric, ferulic and sinapinic acids, where p-coumaric acid was detected in the highest concentration followed by ferulic acid. Overall, the results of this study suggest the powdered formula of H. cordata fermented broth and P. emblica fruit as an alternative medicine for cancer prevention and treatment.

Anti-spasmodic assessment of hydroalcoholic extract and essential oil of aerial part of Pycnocycla caespitosa Boiss. & Hausskn on rat ileum contractions.

PubMed

Sadraei, Hassan; Asghari, Gholamreza; Alipour, Mahdi

2016-01-01

Pycnocycla caespitosa is an essential oil-containing plant naturally growing in southwest of Iran. The extract of this plant has been used as remedy in traditional medicine. Another species of Pycnocyla (P. spinosa) possessed antispasmodic activity. The pharmacological objective of this study was to look for relaxant effect of hydroalcoholic extract and essential oil of P. caespitosa on rat isolated ileum contractions for comparison with loperamide. The essential oil and the hydroalcoholic extract were prepared by hydrodistillation and percolation techniques, respectively. For antispasmodic studies a section of rat ileum was suspended in an organ bath containing Tyrode's solution. The tissue was stimulated with electrical field stimulation (EFS), KCl (80 mM) and acetylcholine (ACh 0.5 μM). The tissue was kept under 1 g tension at 37°C and continuously gassed with O2. The essential oil content in the aerial parts of P. caespitosa was found to be 0.16 % ml/g. The essential oil was analyzed by gas chromatography and gas chromatography-mass spectrometry. Seventy constituents, representing 97 % of the oil were identified. The major components of the oil were carvacrol (7.1%), β-eudesmol (6.4 %), ρ-cymene (5.7%), caryophyllene oxide (3.6%), α-pinine (1.4%) and α-phelandrene (1.1%). The hydroalcoholic extract of P. caespitosa inhibited the response to KCl (IC50 = 48 ± 3 μg/ml), ACh (IC50 = 61 ± 14.7 μg/ml) and EFS (IC50 = 77 ± 17 μg/ml) in a concentration-dependent manner. The essential oil of P. caespitosa also inhibited rat ileum contractions. The IC50 values for KCl, ACh and EFS were 9.2 ± 1.2 μg/ml, 7.6 ± 0.8 μg/ml and 6.4 ± 0.8 μg/ml, respectively. The inhibitory effect of both the essential oil and the extract were reversible. This research confirms the anti-spasmodic activity of both the essential oil and the extract of P. caespitosa on smooth muscle contraction of ileum.

High expression of S100A8 gene is associated with drug resistance to etoposide and poor prognosis in acute myeloid leukemia through influencing the apoptosis pathway.

PubMed

Yang, Xiao-Yan; Zhang, Ming-Ying; Zhou, Qi; Wu, Shui-Yan; Zhao, Ye; Gu, Wei-Ying; Pan, Jian; Cen, Jian-Nong; Chen, Zi-Xing; Guo, Wen-Ge; Chen, Chien-Shing; Yan, Wen-Hua; Hu, Shao-Yan

2016-01-01

S100A8 has been increasingly recognized as a biomarker in multiple solid tumors and has played pivotal roles in hematological malignancies. S100A8 is potentially an indicator for poor survival in acute myeloid leukemia (AML) in retrospective studies. However, the mechanisms of S100A8 are diverse in cancers. In this study, we investigated the correlation of S100A8 at the transcription level with clinical parameters in 91 de novo AML patients and explored its mechanisms of chemoresistance to etoposide in vitro. The transcription level of S100A8 was significantly lower at initial and relapse stages of AML samples than at complete remission (P<0.001) and than in the control group (P=0.0078), while no significant difference could be found between initial and relapse stages (P=0.257). Patients with high transcription levels of S100A8 exhibited a shorter overall survival (P=0.0012). HL-60 cells transfected with S100A8 showed resistance to etoposide with a higher level IC50 value and lower apoptosis rate compared with HL-60 cells transfected with empty vector. Thirty-six genes were significantly downregulated and 12 genes were significantly upregulated in S100A8 overexpression group compared with control group in which 360 genes involved in apoptotic genes array were performed by real-time reverse transcriptase polymerase chain reaction. Among them, the caspase-3, Bcl-2, and Bax were verified by Western blot analysis which indicated that the role of S100A8 in resistance to chemotherapy was closely related with antiapoptosis. In conclusion, critical S100A8 provided useful clinical information in predicting the outcome of AML. The main mechanism of S100A8 which promoted chemoresistance was antiapoptosis.

High expression of S100A8 gene is associated with drug resistance to etoposide and poor prognosis in acute myeloid leukemia through influencing the apoptosis pathway

PubMed Central

Yang, Xiao-yan; Zhang, Ming-ying; Zhou, Qi; Wu, Shui-yan; Zhao, Ye; Gu, Wei-ying; Pan, Jian; Cen, Jian-nong; Chen, Zi-xing; Guo, Wen-ge; Chen, Chien-shing; Yan, Wen-hua; Hu, Shao-yan

2016-01-01

S100A8 has been increasingly recognized as a biomarker in multiple solid tumors and has played pivotal roles in hematological malignancies. S100A8 is potentially an indicator for poor survival in acute myeloid leukemia (AML) in retrospective studies. However, the mechanisms of S100A8 are diverse in cancers. In this study, we investigated the correlation of S100A8 at the transcription level with clinical parameters in 91 de novo AML patients and explored its mechanisms of chemoresistance to etoposide in vitro. The transcription level of S100A8 was significantly lower at initial and relapse stages of AML samples than at complete remission (P<0.001) and than in the control group (P=0.0078), while no significant difference could be found between initial and relapse stages (P=0.257). Patients with high transcription levels of S100A8 exhibited a shorter overall survival (P=0.0012). HL-60 cells transfected with S100A8 showed resistance to etoposide with a higher level IC50 value and lower apoptosis rate compared with HL-60 cells transfected with empty vector. Thirty-six genes were significantly downregulated and 12 genes were significantly upregulated in S100A8 overexpression group compared with control group in which 360 genes involved in apoptotic genes array were performed by real-time reverse transcriptase polymerase chain reaction. Among them, the caspase-3, Bcl-2, and Bax were verified by Western blot analysis which indicated that the role of S100A8 in resistance to chemotherapy was closely related with antiapoptosis. In conclusion, critical S100A8 provided useful clinical information in predicting the outcome of AML. The main mechanism of S100A8 which promoted chemoresistance was antiapoptosis. PMID:27540302

Apparent intermediate K conductance channel hyposmotic activation in human lens epithelial cells.

PubMed

Lauf, Peter K; Misri, Sandeep; Chimote, Ameet A; Adragna, Norma C

2008-03-01

This study explores the nature of K fluxes in human lens epithelial cells (LECs) in hyposmotic solutions. Total ion fluxes, Na-K pump, Cl-dependent Na-K-2Cl (NKCC), K-Cl (KCC) cotransport, and K channels were determined by 85Rb uptake and cell K (Kc) by atomic absorption spectrophotometry, and cell water gravimetrically after exposure to ouabain +/- bumetanide (Na-K pump and NKCC inhibitors), and ion channel inhibitors in varying osmolalities with Na, K, or methyl-d-glucamine and Cl, sulfamate, or nitrate. Reverse transcriptase polymerase chain reaction (RT-PCR), Western blot analyses, and immunochemistry were also performed. In isosmotic (300 mosM) media approximately 90% of the total Rb influx occurred through the Na-K pump and NKCC and approximately 10% through KCC and a residual leak. Hyposmotic media (150 mosM) decreased K(c) by a 16-fold higher K permeability and cell water, but failed to inactivate NKCC and activate KCC. Sucrose replacement or extracellular K to >57 mM, but not Rb or Cs, in hyposmotic media prevented Kc and water loss. Rb influx equaled Kc loss, both blocked by clotrimazole (IC50 approximately 25 microM) and partially by 1-[(2-chlorophenyl) diphenylmethyl]-1H-pyrazole (TRAM-34) inhibitors of the IK channel KCa3.1 but not by other K channel or connexin hemichannel blockers. Of several anion channel blockers (dihydro-indenyl)oxy]alkanoic acid (DIOA), 4-2(butyl-6,7-dichloro-2-cyclopentylindan-1-on-5-yl)oxybutyric acid (DCPIB), and phloretin totally or partially inhibited Kc loss and Rb influx, respectively. RT-PCR and immunochemistry confirmed the presence of KCa3.1 channels, aside of the KCC1, KCC2, KCC3 and KCC4 isoforms. Apparently, IK channels, possibly in parallel with volume-sensitive outwardly rectifying Cl channels, effect regulatory volume decrease in LECs.

Overexpression of Telomerase Reverse Transcriptase Induces Autism-like Excitatory Phenotypes in Mice.

PubMed

Kim, Ki Chan; Rhee, Jeehae; Park, Jong-Eun; Lee, Dong-Keun; Choi, Chang Soon; Kim, Ji-Woon; Lee, Han-Woong; Song, Mi-Ryoung; Yoo, Hee Jeong; Chung, ChiHye; Shin, Chan Young

2016-12-01

In addition to its classical role as a regulator of telomere length, recent reports suggest that telomerase reverse transcriptase (TERT) plays a role in the transcriptional regulation of gene expression such as β-catenin-responsive pathways. Silencing or over-expression of TERT in cultured NPCs demonstrated that TERT induced glutamatergic neuronal differentiation. During embryonic brain development, expression of transcription factors involved in glutamatergic neuronal differentiation was increased in mice over-expressing TERT (TERT-tg mice). We observed increased expression of NMDA receptor subunits and phosphorylation of α-CaMKII in TERT-tg mice. TERT-tg mice showed autism spectrum disorder (ASD)-like behavioral phenotypes as well as lowered threshold against electrically induced seizure. Interestingly, the NMDA receptor antagonist memantine restored behavioral abnormalities in TERT-tg mice. Consistent with the alteration in excitatory/inhibitory (E/I) ratio, TERT-tg mice showed autism-like behaviors, abnormal synaptic organization, and function in mPFC suggesting the role of altered TERT activity in the manifestation of ASD, which is further supported by the significant association of certain SNPs in Korean ASD patients.

Incorporation of deoxyribonucleotides and ribonucleotides by a dNTP-binding cleft mutated reverse transcriptase in hepatitis B virus core particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Hee-Young; Kim, Hye-Young; Jung, Jaesung

2008-01-05

Our recent observation that hepatitis B virus (HBV) DNA polymerase (P) might initiate minus-strand DNA synthesis without primer [Kim et al., (2004) Virology 322, 22-30], raised a possibility that HBV P protein may have the potential to function as an RNA polymerase. Thus, we mutated Phe 436, a bulky amino acid with aromatic side chain, at the putative dNTP-binding cleft in reverse transcriptase (RT) domain of P protein to smaller amino acids (Gly or Val), and examined RNA polymerase activity. HBV core particles containing RT dNTP-binding cleft mutant P protein were able to incorporate {sup 32}P-ribonucleotides, but not HBV coremore » particles containing wild type (wt), priming-deficient mutant, or RT-deficient mutant P proteins. Since all the experiments were conducted with core particles isolated from transfected cells, our results indicate that the HBV RT mutant core particles containing RT dNTP-binding cleft mutant P protein could incorporate both deoxyribonucleotides and ribonucleotides in replicating systems.« less

Emergence of a replicating species from an in vitro RNA evolution reaction

NASA Technical Reports Server (NTRS)

Breaker, R. R.; Joyce, G. F.

1994-01-01

The technique of self-sustained sequence replication allows isothermal amplification of DNA and RNA molecules in vitro. This method relies on the activities of a reverse transcriptase and a DNA-dependent RNA polymerase to amplify specific nucleic acid sequences. We have modified this protocol to allow selective amplification of RNAs that catalyze a particular chemical reaction. During an in vitro RNA evolution experiment employing this modified system, a unique class of "selfish" RNAs emerged and replicated to the exclusion of the intended RNAs. Members of this class of selfish molecules, termed RNA Z, amplify efficiently despite their inability to catalyze the target chemical reaction. Their amplification requires the action of both reverse transcriptase and RNA polymerase and involves the synthesis of both DNA and RNA replication intermediates. The proposed amplification mechanism for RNA Z involves the formation of a DNA hairpin that functions as a template for transcription by RNA polymerase. This arrangement links the two strands of the DNA, resulting in the production of RNA transcripts that contain an embedded RNA polymerase promoter sequence.

Appearance of drug resistance-associated mutations in human immunodeficiency virus type 1 protease and reverse transcriptase derived from drug-treated Indonesian patients.

PubMed

Khairunisa, Siti Qamariyah; Kotaki, Tomohiro; Witaningrum, Adiana Mutamsari; Yunifiar M, Muhammad Qushai; Sukartiningrum, Septhia Dwi; Nasronudin; Kameoka, Masanori

2015-02-01

Although HIV-1 drug resistance is a major obstacle in Indonesia, information on drug resistance is limited. In this study, the viral subtype and appearance of drug resistance mutations in the HIV-1 protease (PR) and reverse transcriptase (RT) genes were determined among drug-treated, HIV-1-infected patients in Surabaya. HIV-1 patients who received antiretroviral therapy (ART) more than 2 years were randomly recruited regardless of the viral load or ART failure. Fifty-eight HIV-1 PR genes and 53 RT genes were sequenced. CRF01_AE viruses were identified as the predominant strain. Major drug resistance mutations were not detected in the PR genes. In contrast, 37.7% (20/53) of the participants had one or more major drug resistance mutations in the RT genes, predominantly M184V (28.3%), K103N (11.3%), and thymidine analogue mutations (TAMs) (20.8%). The high prevalence of drug resistance mutations in RT genes indicated the necessity of monitoring the effectiveness of ART in Indonesia.

Molecular Characterization of the Human Immunodeficiency Virus Type 1 in Women and Their Vertically Infected Children.

PubMed

Vaz, Sara Nunes; Giovanetti, Marta; Rego, Filipe Ferreira de Almeida; Oliveira, Tulio de; Danaviah, Siva; Gonçalves, Maria Luiza Freire; Alcantara, Luiz Carlos Junior; Brites, Carlos

2015-10-01

Approximately 35 million people worldwide are infected with human immunodeficiency virus (HIV) around 3.2 million of whom are children under 15 years. Mother-to-child-transmission (MTCT) of HIV-1 accounts for 90% of all infections in children. Despite great advances in the prevention of MTCT in Brazil, children are still becoming infected. Samples from 19 HIV-1-infected families were collected. DNA was extracted and fragments from gag, pol, and env were amplified and sequenced directly. Phylogenetic reconstruction was performed. Drug resistance analyses were performed in pol and env sequences. We found 82.1% of subtype B and 17.9% of BF recombinants. A prevalence of 43.9% drug resistance-associated mutations in pol sequences was identified. Of the drug-naive children 33.3% presented at least one mutation related to protease inhibitor/nucleoside reverse transcriptase inhibitor/nonnucleoside reverse transcriptase inhibitor (PI/NRTI/NNRTI) resistance. The prevalence of transmitted drug resistance mutations was 4.9%. On env we found a low prevalence of HR1 (4.9%) and HR2 (14.6%) mutations.

Reverse transcriptase polymerase chain reaction on fine needle aspirates for rapid detection of translocations in synovial sarcoma.

PubMed

Nilsson, G; Wang, M; Wejde, J; Kanter, L; Karlén, J; Tani, E; Kreicbergs, A; Larsson, O

1998-01-01

To evaluate the utilization of fine needle aspiration (FNA) biopsy to obtain material for reverse-transcriptase polymerase chain reaction (RT-PCR) in the detection of the t(X;18)(p11.2;q11.2) translocation in synovial sarcomas. We applied RT-PCR to detection of synovial sarcoma fusion gene transcripts on fine needle aspirates. Five clinical samples were first analyzed: one was a tumor previously diagnosed as malignant hemangiopericytoma, one was a poorly defined tumor, and three were suspected synovial sarcomas. FNA material was transferred directly to the RT-PCR reaction tube without RNA extraction. The t(X;18) translocation could be detected on the limited amount of material that FNA provides. In each of the cases studied the representivity of the tumor samples was confirmed microscopically. Our protocol permits analysis directly on representative samples without extraction of RNA. The results imply that RT-PCR offers reliable detection of sarcoma fusion gene transcripts on fine needle aspirates. The procedure, apart from being applicable to outpatients, is rapid and sensitive.

Effect of saliva stabilisers on detection of porcine reproductive and respiratory syndrome virus in oral fluid by quantitative reverse transcriptase real-time PCR.

PubMed

Decorte, Inge; Van der Stede, Yves; Nauwynck, Hans; De Regge, Nick; Cay, Ann Brigitte

2013-08-01

This study evaluated the effect of extraction-amplification methods, storage temperature and saliva stabilisers on detection of porcine reproductive and respiratory syndrome virus (PRRSV) RNA by quantitative reverse transcriptase real-time PCR (qRT-PCR) in porcine oral fluid. The diagnostic performance of different extraction-amplification methods was examined using a dilution series of oral fluid spiked with PRRSV. To determine RNA stability, porcine oral fluid, with or without commercially available saliva stabilisers, was spiked with PRRSV, stored at 4°C or room temperature and tested for the presence of PRRSV RNA by qRT-PCR. PRRSV RNA could be detected in oral fluid using all extraction-amplification combinations, but the limit of detection varied amongst different combinations. Storage temperature and saliva stabilisers had an effect on the stability of PRRSV RNA, which could only be detected for 7 days when PRRSV spiked oral fluid was kept at 4°C or stabilised at room temperature with a commercial mRNA stabiliser. Copyright © 2013 Elsevier Ltd. All rights reserved.

Crystal structures of the reverse transcriptase-associated ribonuclease H domain of xenotropic murine leukemia-virus related virus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Dongwen; Chung, Suhman; Miller, Maria

2012-06-19

The ribonuclease H (RNase H) domain of retroviral reverse transcriptase (RT) plays a critical role in the life cycle by degrading the RNA strands of DNA/RNA hybrids. In addition, RNase H activity is required to precisely remove the RNA primers from nascent (-) and (+) strand DNA. We report here three crystal structures of the RNase H domain of xenotropic murine leukemia virus-related virus (XMRV) RT, namely (i) the previously identified construct from which helix C was deleted, (ii) the intact domain, and (iii) the intact domain complexed with an active site {alpha}-hydroxytropolone inhibitor. Enzymatic assays showed that the intactmore » RNase H domain retained catalytic activity, whereas the variant lacking helix C was only marginally active, corroborating the importance of this helix for enzymatic activity. Modeling of the enzyme-substrate complex elucidated the essential role of helix C in binding a DNA/RNA hybrid and its likely mode of recognition. The crystal structure of the RNase H domain complexed with {beta}-thujaplicinol clearly showed that coordination by two divalent cations mediates recognition of the inhibitor.« less

Apoptosis and reduced cell proliferation of HL-60 cell line caused by human telomerase reverse transcriptase inhibition by siRNA.

PubMed

Miri-Moghaddam, Ebrahim; Deezagi, Abdolkhaleg; Soheili, Zahra Sohaila; Shariati, Parvin

2010-01-01

The close correlation between telomerase activity and human telomerase reverse transcriptase (hTERT) expression has made hTERT to be considered as a selective molecular target for human cancer therapy. In this study, the ability of short-interfering RNA (siRNA) to downregulate hTERT expression and its correlation with cell growth and apoptosis in the promyelocytic cell line HL-60 was evaluated. hTERT siRNA was designed and transfected to HL-60. hTERT mRNA expression, cell proliferation and apoptotic cells were measured. The results indicated that hTERT siRNA resulted in 97.2 ± 0.6% downregulation of the hTERT mRNA content; inhibition of the cell proliferation rate was about 52.8 ± 2.3% and the apoptotic index of cells was 30.5 ± 1.5%. hTERT plays an essential role in cell proliferation and control of the viability of leukemic cells, thus promising the development of drugs for leukemia. Copyright © 2010 S. Karger AG, Basel.

A novel Met-to-Thr mutation in the YMDD motif of reverse transcriptase from feline immunodeficiency virus confers resistance to oxathiolane nucleosides.

PubMed Central

Smith, R A; Remington, K M; Lloyd, R M; Schinazi, R F; North, T W

1997-01-01

Variants of feline immunodeficiency virus (FIV) that possess a unique methionine-to-threonine mutation within the YMDD motif of reverse transcriptase (RT) were selected by culturing virus in the presence of inhibitory concentrations of (-)-beta-L-2',3'-dideoxy-5-fluoro-3'-thiacytidine [(-)-FTC]. The mutants were resistant to (-)-FTC and (-)-beta-L-2',3'-dideoxy-3'-thiacytidine (3TC) and additionally exhibited low-level resistance to 2',3'-dideoxycytidine (ddC). DNA sequence analysis of the RT-encoding region of the pol gene amplified from resistant viruses consistently identified a Met-to-Thr mutation in the YMDD motif. Purified RT from the mutants was also resistant to the 5'-triphosphate forms of 3TC, (-)-FTC, and ddC. Site-directed mutants of FIV were engineered which contain either the novel Met-to-Thr mutation or the Met-to-Val mutation seen in oxathiolane nucleoside-resistant HIV-1. Both site-directed mutants displayed resistance to 3TC, thus confirming the role of these mutations in the resistance of FIV to beta-L-3'-thianucleosides. PMID:9032372

Schizosaccharomyces pombe Retrotransposon Tf2 Mobilizes Primarily through Homologous cDNA Recombination

PubMed Central

Hoff, Eleanor F.; Levin, Henry L.; Boeke, Jef D.

1998-01-01

The Tf2 retrotransposon, found in the fission yeast Schizosaccharomyces pombe, is nearly identical to its sister element, Tf1, in its reverse transcriptase-RNase H and integrase domains but is very divergent in the gag domain, the protease, the 5′ untranslated region, and the U3 domain of the long terminal repeats. It has now been demonstrated that a neo-marked copy of Tf2 overexpressed from a heterologous promoter can mobilize into the S. pombe genome and produce true transposition events. However, the Tf2-neo mobilization frequency is 10- to 20-fold lower than that of Tf1-neo, and 70% of the Tf2-neo events are homologous recombination events generated independently of a functional Tf2 integrase. Thus, the Tf2 element is primarily dependent on homologous recombination with preexisting copies of Tf2 for its propagation. Finally, production of Tf2-neo proteins and cDNA was also analyzed; surprisingly, Tf2 was found to produce its reverse transcriptase as a single species in which it is fused to protease, unlike all other retroviruses and retrotransposons. PMID:9774697

The Reverse Transcriptases Associated with CRISPR-Cas Systems.

PubMed

Toro, Nicolás; Martínez-Abarca, Francisco; González-Delgado, Alejandro

2017-08-02

CRISPR (clustered regularly interspaced short palindromic repeats) and associated proteins (Cas) act as adaptive immune systems in bacteria and archaea. Some CRISPR-Cas systems have been found to be associated with putative reverse transcriptases (RT), and an RT-Cas1 fusion associated with a type III-B system has been shown to acquire RNA spacers in vivo. Nevertheless, the origin and evolutionary relationships of these RTs and associated CRISPR-Cas systems remain largely unknown. We performed a comprehensive phylogenetic analysis of these RTs and associated Cas1 proteins, and classified their CRISPR-Cas modules. These systems were found predominantly in bacteria, and their presence in archaea may be due to a horizontal gene transfer event. These RTs cluster into 12 major clades essentially restricted to particular phyla, suggesting host-dependent functioning. The RTs and associated Cas1 proteins may have largely coevolved. They are, therefore, subject to the same selection pressures, which may have led to coadaptation within particular protein complexes. Furthermore, our results indicate that the association of an RT with a CRISPR-Cas system has occurred on multiple occasions during evolution.

Direct and quantitative detection of HIV-1 RNA in human plasma with a branched DNA signal amplification assay.

PubMed

Urdea, M S; Wilber, J C; Yeghiazarian, T; Todd, J A; Kern, D G; Fong, S J; Besemer, D; Hoo, B; Sheridan, P J; Kokka, R

1993-11-01

To determine the relative effect of sample matrix on the quantitation of HIV RNA in plasma. Two HIV-positive specimens were diluted into five and 10 different HIV-negative plasma samples, respectively. Branched DNA signal amplification technology and reverse-transcriptase polymerase chain reaction were used to measure the viral load. In one sample the viral load by polymerase chain reaction ranged from undetectable to 1.9 x 10(5) copies/ml, and the branched DNA results ranged from 2.6 x 10(4) to 4.2 x 10(4) HIV RNA equivalent/ml. In the other sample the corresponding figures were 6.3 x 10(4) to 5.5 x 10(5) copies/ml and 5.7 x 10(4) to 7.5 x 10(4) HIV RNA equivalents/ml. In contrast to reverse-transcriptase polymerase chain reaction the branched DNA signal amplification assay does not require a separate extraction step or enzymatic amplification of the target. Therefore this measurement is less affected by the sample matrix and the signal generated is directly proportional to the viral load.

DMS-MaPseq for genome-wide or targeted RNA structure probing in vivo

PubMed Central

Zubradt, Meghan; Gupta, Paromita; Persad, Sitara; Lambowitz, Alan M.; Weissman, Jonathan S.; Rouskin, Silvi

2017-01-01

Coupling structure-specific in vivo chemical modification to next-generation sequencing is transforming RNA secondary structural studies in living cells. The dominant strategy for detecting in vivo chemical modifications uses reverse transcriptase truncation products, which introduces biases and necessitates population-average assessments of RNA structure. Here we present dimethyl sulfate mutational profiling with sequencing (DMS-MaPseq), which encodes DMS modifications as mismatches using a thermostable group II intron reverse transcriptase (TGIRT). DMS-MaPseq yields a high signal-to-noise ratio, can report multiple structural features per molecule, and allows both genome-wide studies and focused in vivo investigations of even low abundance RNAs. We apply DMS-MaPseq for the first analysis of RNA structure within an animal tissue and to identify a functional structure involved in non-canonical translation initiation. Additionally, we use DMS-MaPseq to compare the in vivo structure of pre-mRNAs to their mature isoforms. These applications illustrate DMS-MaPseq’s capacity to dramatically expand in vivo analysis of RNA structure. PMID:27819661

Micronuclei induced by reverse transcriptase inhibitors in mononucleated and binucleated cells as assessed by the cytokinesis-block micronucleus assay

PubMed Central

2010-01-01

This study evaluated the clastogenic and/or aneugenic potential of three nucleoside reverse transcriptase inhibitors (zidovudine - AZT, lamivudine - 3TC and stavudine - d4T) using the cytokinesis-block micronucleus (CBMN) assay in human lymphocyte cultures. All three inhibitors produced a positive response when tested in binucleated cells. The genotoxicity of AZT and 3TC was restricted to binucleated cells since there was no significant increase in the frequency of micronuclei in mononucleated cells. This finding indicated that AZT and 3TC caused chromosomal breakage and that their genotoxicity was related to a clastogenic action. In addition to the positive response observed with d4T in binucleated cells, this drug also increased the frequency of micronuclei in mononucleated cells, indicating clastogenic and aneugenic actions. Since the structural differences between AZT and 3TC and AZT and d4T involve the 3' position in the 2'-deoxyribonucleoside and in an unsaturated 2',3',dideoxyribose, respectively, we suggest that an unsaturated 2', 3', dideoxyribose is responsible for the clastogenic and aneugenic actions of d4T. PMID:21637587

Effect of Her-2/neu Signaling on Sensitivity to TRAIL in Prostate Cancer

DTIC Science & Technology

2005-06-01

cytokines (18), and matrix metalloprotease inhibitors (19) are able to render TRAIL-resistant tumor cells sensitive to TRAIL apoptosis. In recent...TRAIL-induced cytotoxicity. As DU-145 cells were treated with acetyl salicylic acid (ASA: aspirin), an inhibitor of IKK , we observed that TRAIL...sulfide (IC50 = 1.02 M for COX-1 and IC50 = 10.43 M for COX-2), NS-398 (a selective COX-2 inhibitor ; IC50 = 4.81 M for COX-1 and IC50 = 0.47 M for COX-2

Neurotoxicity screening of new psychoactive substances (NPS): Effects on neuronal activity in rat cortical cultures using microelectrode arrays (MEA).

PubMed

Zwartsen, Anne; Hondebrink, Laura; Westerink, Remco Hs

2018-05-01

While the prevalence and the use of new psychoactive substances (NPS) is steadily increasing, data on pharmacological, toxicological and clinical effects is limited. Considering the large number of NPS available, there is a clear need for efficient in vitro screening techniques that capture multiple mechanisms of action. Neuronal cultures grown on multi-well microelectrode arrays (mwMEAs) have previously proven suitable for neurotoxicity screening of chemicals, pharmaceuticals and (illicit) drugs. We therefore used rat primary cortical cultures grown on mwMEA plates to investigate the effects of eight NPS (PMMA, α-PVP, methylone, MDPV, 2C-B, 25B-NBOMe, BZP and TFMPP) and two 'classic' illicit drugs (cocaine, methamphetamine) on spontaneous neuronal activity. All tested drugs rapidly and concentration-dependently decreased the weighted mean firing rate (wMFR) and the weighted mean burst rate (wMBR) during a 30 min acute exposure. Of the 'classic' drugs, cocaine most potently inhibited the wMFR (IC 50 9.8 μM), whereas methamphetamine and the structurally-related NPS PMMA were much less potent (IC 50 100 μM and IC 50 112 μM, respectively). Of the cathinones, MDPV and α-PVP showed comparable IC 50 values (29 μM and 21 μM, respectively), although methylone was 10-fold less potent (IC 50 235 μM). Comparable 10-fold differences in potency were also observed between the hallucinogenic phenethylamines 2C-B (IC 50 27 μM) and 25B-NBOMe (IC 50 2.4 μM), and between the piperazine derivatives BZP (IC 50 161 μM) and TFMPP (IC 50 19 μM). All drugs also inhibited the wMBR and concentration-response curves for wMBR and wMFR were comparable. For most drugs, IC 50 values are close to the estimated human brain concentrations following recreational doses of these drugs, highlighting the importance of this efficient in vitro screening approach for classification and prioritization of emerging NPS. Moreover, the wide range of IC 50 values observed for these and previously tested drugs of abuse, both within and between different classes of NPS, indicates that additional investigation of structure-activity relationships could aid future risk assessment of emerging NPS. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Characterization of the Commercially-Available Fluorescent Chloroquine-BODIPY Conjugate, LynxTag-CQGREEN, as a Marker for Chloroquine Resistance and Uptake in a 96-Well Plate Assay

PubMed Central

Chan, Kitti W. K.; Choy, Kit-Ying; Rénia, Laurent; Russell, Bruce; Lear, Martin J.; Nosten, François H.; Tan, Kevin S. W.; Chow, Larry M. C.

2014-01-01

Chloroquine was a cheap, extremely effective drug against Plasmodium falciparum until resistance arose. One approach to reversing resistance is the inhibition of chloroquine efflux from its site of action, the parasite digestive vacuole. Chloroquine accumulation studies have traditionally relied on radiolabelled chloroquine, which poses several challenges. There is a need for development of a safe and biologically relevant substitute. We report here a commercially-available green fluorescent chloroquine-BODIPY conjugate, LynxTag-CQGREEN, as a proxy for chloroquine accumulation. This compound localized to the digestive vacuole of the parasite as observed under confocal microscopy, and inhibited growth of chloroquine-sensitive strain 3D7 more extensively than in the resistant strains 7G8 and K1. Microplate reader measurements indicated suppression of LynxTag-CQGREEN efflux after pretreatment of parasites with known reversal agents. Microsomes carrying either sensitive- or resistant-type PfCRT were assayed for uptake; resistant-type PfCRT exhibited increased accumulation of LynxTag-CQGREEN, which was suppressed by pretreatment with known chemosensitizers. Eight laboratory strains and twelve clinical isolates were sequenced for PfCRT and Pgh1 haplotypes previously reported to contribute to drug resistance, and pfmdr1 copy number and chloroquine IC50s were determined. These data were compared with LynxTag-CQGREEN uptake/fluorescence by multiple linear regression to identify genetic correlates of uptake. Uptake of the compound correlated with the logIC50 of chloroquine and, more weakly, a mutation in Pgh1, F1226Y. PMID:25343249

Anticholinesterase and antioxidant investigations of crude extracts, subsequent fractions, saponins and flavonoids of atriplex laciniata L.: potential effectiveness in Alzheimer's and other neurological disorders.

PubMed

Kamal, Zul; Ullah, Farhat; Ayaz, Muhammad; Sadiq, Abdul; Ahmad, Sajjad; Zeb, Anwar; Hussain, Abid; Imran, Muhammad

2015-04-01

Atriplex laciniata L. was investigated for phenolic, flavonoid contents, antioxidant, anticholinesterase activities, in an attempt to explore its effectiveness in Alzheimer's and other neurological disorders. Plant crude methanolic extract (Al.MeF), subsequent fractions; n-hexane (Al.HxF), chloroform (Al.CfF), ethyl acetate (Al.EaF), aqueous (Al.WtF), Saponins (Al.SPF) and Flavonoids (Al.FLVF) were investigated for DPPH, ABTS and H2O2 free radical scavenging activities. Further these extracts were subjected to acetylcholinesterase (AChE) & butyrylcholinesterase (BChE) inhibitory activities using Ellman's assay. Phenolic and Flavonoid contents were determined and expressed in mg Gallic acid GAE/g and Rutin RTE/g of samples respectively. In DPPH free radicals scavenging assay, Al.FLVF, Al.SPF and Al.MeF showed highest activity causing 89.41 ± 0.55, 83.37 ± 0.34 and 83.37 ± 0.34% inhibition of free radicals respectively at 1 mg/mL concentration. IC50 for these fractions were 33, 83 and 82 μg/mL respectively. Similarly, plant extracts showed high ABTS scavenging potential, i.e. Al.FLVF (90.34 ± 0.55), Al.CfF (83.42 ± 0.57), Al.MeF (81.49 ± 0.60) with IC50 of 30, 190 and 70 μg/ml respectively. further, H2O2 percent scavenging was highly appraised in Al.FLVF (91.29 ± 0.53, IC50 75), Al.SPF (85.35 ± 0.61, IC50 70) and Al.EaF (83.48 ± 0.67, IC50 270 μg/mL). All fractions exhibited concentration dependent AChE inhibitory activity as; Al.FLVF, 88.31 ± 0.57 (IC50 70 μg/mL), Al.SPF, 84.36 ± 0.64 (IC50 90 μg/mL), Al.MeF, 78.65 ± 0.70 (IC50 280 μg/mL), Al.EaF, 77.45 ± 0.46 (IC50 270 μg/mL) and Al.WtF 72.44 ± 0.58 (IC50 263 μg/mL) at 1 mg/mL. Likewise the percent BChE inhibitory activity was most obvious in Al.FLVF 85.46 ± 0.62 (IC50 100 μg/mL), Al.CfF 83.49 ± 0.46 (IC50 160 μg/mL), Al.MeF 82.68 ± 0.60 (IC50 220 μg/mL) and Al.SPF 80.37 ± 0.54 (IC50 120 μg/mL). These results stipulate that A. laciniata is enriched with phenolic and flavonoid contents that possess significant antioxidant and anticholinestrase effects. This provide pharmacological basis for the presence of compounds that may be effective in Alzheimer's and other neurological disorders.

Geissoschizine methyl ether, a corynanthean-type indole alkaloid from Uncaria rhynchophylla as a potential acetylcholinesterase inhibitor.

PubMed

Yang, Zhong-Duo; Duan, Dong-Zhu; Du, Juan; Yang, Ming-Jun; Li, Shuo; Yao, Xiao-Jun

2012-01-01

Geissoschizine methyl ether (1), a newly discovered strong acetylcholinesterase (AChE) inhibitor, along with six weakly active alkaloids, vallesiachotamine (2), hisuteine (3), hirsutine (4), isorhynchophylline (5), cisocorynoxeine (6) and corynoxeine (7) have been isolated from Uncaria rhynchophylla. Geissoschizine methyl ether (1) inhibited 50% of AChE activity at concentrations of 3.7 ± 0.3 µg mL(-1) while the IC(50) value of physostigmine as a standard was 0.013 ± 0.002 µg mL(-1). The mode of AChE inhibition by 1 was reversible and non-competitive. In addition, molecular modelling was performed to explore the binding mode of inhibitor 1 at the active site of AChE.

Emergence of uncommon HIV-1 non-B subtypes and circulating recombinant forms and trends in transmission of antiretroviral drug resistance in patients with primary infection during the 2013-2015 period in Marseille, Southeastern France.

PubMed

Tamalet, Catherine; Tissot-Dupont, Hervé; Motte, Anne; Tourrès, Christian; Dhiver, Catherine; Ravaux, Isabelle; Poizot-Martin, Isabelle; Dieng, Thérèse; Tomei, Christelle; Bregigeon, Sylvie; Zaegel-Faucher, Olivia; Laroche, Hélène; Aherfi, Sarah; Mokhtari, Saadia; Chaudet, Hervé; Ménard, Amelie; Brouqui, Philippe; Stein, Andreas; Colson, Philippe

2018-05-24

Primary HIV-1 infections (PHI) with non-B subtypes are increasing in developed countries while transmission of HIV-1 harboring antiretroviral resistance-associated mutations (RAMs) remains a concern. This study assessed non-B HIV-1 subtypes and RAMs prevalence among patients with PHI in university hospitals of Marseille, Southeastern France, in 2005-2015 (11 years). HIV-1 sequences were obtained by in-house protocols from 115 patients with PHI, including 38 for the 2013-2015 period. On the basis of the phylogenetic analysis of the reverse transcriptase region, non-B subtypes were identified in 31% of these patients. They included 3 different subtypes (3A, 1C, 4F), 23 circulating recombinant forms (CRFs) (CRF02_AG, best BLAST hits being CRF 36_cpx and CRF30 in 7 and 1 cases, respectively), and 5 unclassified sequences (U). Non-B subtypes proportion increased significantly, particularly in 2011-2013 vs in 2005-2010 (P = .03). CRF02_AG viruses largely predominated in 2005-2013 whereas atypical strains more difficult to classify and undetermined recombinants emerged recently (2014-2015). The prevalence of protease, nucleos(t)ide reverse transcriptase, and first-generation nonnucleoside reverse transcriptase inhibitors-associated RAMs were 1.7% (World Health Organization [WHO] list, 2009/2.6% International AIDS Society [IAS] list, 2017), 5.2%/4.3%, and 5.2%/5.2%, respectively. Etravirine/rilpivirine-associated RAM (IAS) prevalence was 4.3%. Men who have sex with men (MSM) were more frequently infected with drug-resistant viruses than other patients (26% vs 7%; P = .011). The recent increase of these rare HIV-1 strains and the spread of drug-resistant HIV-1 among MSM in Southeastern France might be considered when implementing prevention strategies and starting therapies. © 2018 Wiley Periodicals, Inc.

Deep sequencing analysis of HIV-1 reverse transcriptase at baseline and time of failure in patients receiving rilpivirine in the phase III studies ECHO and THRIVE.

PubMed

Van Eygen, Veerle; Thys, Kim; Van Hove, Carl; Rimsky, Laurence T; De Meyer, Sandra; Aerssens, Jeroen; Picchio, Gaston; Vingerhoets, Johan

2016-05-01

Minority variants (1.0-25.0%) were evaluated by deep sequencing (DS) at baseline and virological failure (VF) in a selection of antiretroviral treatment-naïve, HIV-1-infected patients from the rilpivirine ECHO/THRIVE phase III studies. Linkage between frequently emerging resistance-associated mutations (RAMs) was determined. DS (llIumina®) and population sequencing (PS) results were available at baseline for 47 VFs and time of failure for 48 VFs; and at baseline for 49 responders matched for baseline characteristics. Minority mutations were accurately detected at frequencies down to 1.2% of the HIV-1 quasispecies. No baseline minority rilpivirine RAMs were detected in VFs; one responder carried 1.9% F227C. Baseline minority mutations associated with resistance to other non-nucleoside reverse transcriptase inhibitors (NNRTIs) were detected in 8/47 VFs (17.0%) and 7/49 responders (14.3%). Baseline minority nucleoside/nucleotide reverse transcriptase inhibitor (NRTI) RAMs M184V and L210W were each detected in one VF (none in responders). At failure, two patients without NNRTI RAMs by PS carried minority rilpivirine RAMs K101E and/or E138K; and five additional patients carried other minority NNRTI RAMs V90I, V106I, V179I, V189I, and Y188H. Overall at failure, minority NNRTI RAMs and NRTI RAMs were found in 29/48 (60.4%) and 16/48 VFs (33.3%), respectively. Linkage analysis showed that E138K and K101E were usually not observed on the same viral genome. In conclusion, baseline minority rilpivirine RAMs and other NNRTI/NRTI RAMs were uncommon in the rilpivirine arm of the ECHO and THRIVE studies. DS at failure showed emerging NNRTI resistant minority variants in seven rilpivirine VFs who had no detectable NNRTI RAMs by PS. © 2015 Wiley Periodicals, Inc.

A Combination Microbicide Gel Protects Macaques Against Vaginal Simian Human Immunodeficiency Virus-Reverse Transcriptase Infection, But Only Partially Reduces Herpes Simplex Virus-2 Infection After a Single High-Dose Cochallenge

PubMed Central

Hsu, Mayla; Aravantinou, Meropi; Menon, Radhika; Seidor, Samantha; Goldman, Daniel; Kenney, Jessica; Derby, Nina; Gettie, Agegnehu; Blanchard, James; Piatak, Michael; Lifson, Jeffrey D.; Fernández-Romero, Jose A.; Zydowsky, Thomas M.

2014-01-01

Abstract Herpes simplex virus-2 (HSV-2) infection increases HIV susceptibility. We previously established a rhesus macaque model of vaginal HSV-2 preexposure followed by cochallenge with HSV-2 and simian/human immunodeficiency virus-reverse transcriptase (SHIV-RT). Using this model, we showed that a gel containing the nonnucleoside reverse transcriptase inhibitor (NNRTI) MIV-150 in carrageenan (CG) reduced SHIV-RT infection. To evaluate the efficacy of new generation microbicides against both viruses, we first established dual infection after single vaginal cochallenge with SHIV-RT and HSV-2 in HSV-2-naive macaques. All animals (6/6) became HSV-2 infected, with 4/6 coinfected with SHIV-RT. In a control group cochallenged with SHIV-RT and UV-inactivated HSV-2, 2/4 became SHIV-RT infected, and none had detectable HSV-2. Low-level HSV-2-specific antibody and T cell responses were detected in some HSV-2-infected animals. To test a CG gel containing MIV-150 and zinc acetate (MZC), which provided naive animals full protection from SHIV-RT for at least 8 h, MZC (vs. CG) was applied daily for 14 days followed by cochallenge 8 h later. MZC prevented SHIV-RT infection (0/9 infected, p=0.04 vs. 3/6 in CG controls), but only reduced HSV-2 infection by 20% (6/9 infected vs. 5/6 in CG, p=0.6). In HSV-2-infected animals, none of the gel-treated animals seroconverted, and only the CG controls had measurable HSV-2-specific T cell responses. This study shows the promise of MZC to prevent immunodeficiency virus infection (even in the presence of HSV-2) and reduce HSV-2 infection after exposure to a high-dose inoculum. Additionally, it demonstrates the potential of a macaque coinfection model to evaluate broad-spectrum microbicides. PMID:24117013

A combination microbicide gel protects macaques against vaginal simian human immunodeficiency virus-reverse transcriptase infection, but only partially reduces herpes simplex virus-2 infection after a single high-dose cochallenge.

PubMed

Hsu, Mayla; Aravantinou, Meropi; Menon, Radhika; Seidor, Samantha; Goldman, Daniel; Kenney, Jessica; Derby, Nina; Gettie, Agegnehu; Blanchard, James; Piatak, Michael; Lifson, Jeffrey D; Fernández-Romero, Jose A; Zydowsky, Thomas M; Robbiani, Melissa

2014-02-01

Herpes simplex virus-2 (HSV-2) infection increases HIV susceptibility. We previously established a rhesus macaque model of vaginal HSV-2 preexposure followed by cochallenge with HSV-2 and simian/human immunodeficiency virus-reverse transcriptase (SHIV-RT). Using this model, we showed that a gel containing the nonnucleoside reverse transcriptase inhibitor (NNRTI) MIV-150 in carrageenan (CG) reduced SHIV-RT infection. To evaluate the efficacy of new generation microbicides against both viruses, we first established dual infection after single vaginal cochallenge with SHIV-RT and HSV-2 in HSV-2-naive macaques. All animals (6/6) became HSV-2 infected, with 4/6 coinfected with SHIV-RT. In a control group cochallenged with SHIV-RT and UV-inactivated HSV-2, 2/4 became SHIV-RT infected, and none had detectable HSV-2. Low-level HSV-2-specific antibody and T cell responses were detected in some HSV-2-infected animals. To test a CG gel containing MIV-150 and zinc acetate (MZC), which provided naive animals full protection from SHIV-RT for at least 8 h, MZC (vs. CG) was applied daily for 14 days followed by cochallenge 8 h later. MZC prevented SHIV-RT infection (0/9 infected, p=0.04 vs. 3/6 in CG controls), but only reduced HSV-2 infection by 20% (6/9 infected vs. 5/6 in CG, p=0.6). In HSV-2-infected animals, none of the gel-treated animals seroconverted, and only the CG controls had measurable HSV-2-specific T cell responses. This study shows the promise of MZC to prevent immunodeficiency virus infection (even in the presence of HSV-2) and reduce HSV-2 infection after exposure to a high-dose inoculum. Additionally, it demonstrates the potential of a macaque coinfection model to evaluate broad-spectrum microbicides.

HIV type-1 genotypic resistance profiles in vertically infected patients from Argentina reveal an association between K103N+L100I and L74V mutations.

PubMed

Aulicino, Paula C; Rocco, Carlos A; Mecikovsky, Debora; Bologna, Rosa; Mangano, Andrea; Sen, Luisa

2010-01-01

Patterns and pathways of HIV type-1 (HIV-1) antiretroviral (ARV) drug resistance-associated mutations in clinical isolates are conditioned by ARV history and factors such as viral subtype and fitness. Our aim was to analyse the frequency and association of ARV drug resistance mutations in a group of long-term vertically infected patients from Argentina. Plasma samples from 71 patients (38 children and 33 adolescents) were collected for genotypic HIV-1 ARV resistance testing during the period between February 2006 and October 2008. Statistically significant pairwise associations between ARV resistance mutations in pol, as well as associations between mutations and drug exposure, were identified using Fisher's exact tests with Bonferroni and false discovery rate corrections. Phylogenetic analyses were performed for subtype assignment. In protease (PR), resistance-associated mutations M46I/L, I54M/L/V/A/S and V82A/F/T/S/M/I were associated with each other and with minor mutations at codons 10, 24 and 71. Mutations V82A/F/T/S/M/I were primarily selected by the administration of ritonavir (RTV) in an historical ARV regimen. In reverse transcriptase, thymidine analogue mutation (TAM)1 profile was more common than TAM2. The non-nucleoside K103N+L100I mutations were observed at high frequency (15.5%) and were significantly associated with the nucleoside mutation L74V in BF recombinants. Associations of mutations at PR sites reflect the frequent use of RTV at an early time in this group of patients and convergent resistance mechanisms driven by the high exposure to protease inhibitors, as well as local HIV-1 diversity. The results provide clinical evidence of a molecular interaction between K103N+L100I and L74V mutations at the reverse transcriptase gene in vivo, limiting the future use of second-generation non-nucleoside reverse transcriptase inhibitors such as etravirine.

Detection of Anti-Hepatitis B Virus Drug Resistance Mutations Based on Multicolor Melting Curve Analysis.

PubMed

Mou, Yi; Athar, Muhammad Ammar; Wu, Yuzhen; Xu, Ye; Wu, Jianhua; Xu, Zhenxing; Hayder, Zulfiqar; Khan, Saeed; Idrees, Muhammad; Nasir, Muhammad Israr; Liao, Yiqun; Li, Qingge

2016-11-01

Detection of anti-hepatitis B virus (HBV) drug resistance mutations is critical for therapeutic decisions for chronic hepatitis B virus infection. We describe a real-time PCR-based assay using multicolor melting curve analysis (MMCA) that could accurately detect 24 HBV nucleotide mutations at 10 amino acid positions in the reverse transcriptase region of the HBV polymerase gene. The two-reaction assay had a limit of detection of 5 copies per reaction and could detect a minor mutant population (5% of the total population) with the reverse transcriptase M204V amino acid mutation in the presence of the major wild-type population when the overall concentration was 10 4 copies/μl. The assay could be finished within 3 h, and the cost of materials for each sample was less than $10. Clinical validation studies using three groups of samples from both nucleos(t)ide analog-treated and -untreated patients showed that the results for 99.3% (840/846) of the samples and 99.9% (8,454/8,460) of the amino acids were concordant with those of Sanger sequencing of the PCR amplicon from the HBV reverse transcriptase region (PCR Sanger sequencing). HBV DNA in six samples with mixed infections consisting of minor mutant subpopulations was undetected by the PCR Sanger sequencing method but was detected by MMCA, and the results were confirmed by coamplification at a lower denaturation temperature-PCR Sanger sequencing. Among the treated patients, 48.6% (103/212) harbored viruses that displayed lamivudine monoresistance, adefovir monoresistance, entecavir resistance, or lamivudine and adefovir resistance. Among the untreated patients, the Chinese group had more mutation-containing samples than did the Pakistani group (3.3% versus 0.56%). Because of its accuracy, rapidness, wide-range coverage, and cost-effectiveness, the real-time PCR assay could be a robust tool for the detection if anti-HBV drug resistance mutations in resource-limited countries. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Protein-mediated antagonism between HIV reverse transcriptase ligands nevirapine and MgATP.

PubMed

Zheng, Xunhai; Mueller, Geoffrey A; DeRose, Eugene F; London, Robert E

2013-06-18

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) play a central role in the treatment of AIDS, but their mechanisms of action are incompletely understood. The interaction of the NNRTI nevirapine (NVP) with HIV-1 reverse transcriptase (RT) is characterized by a preference for the open conformation of the fingers/thumb subdomains, and a reported variation of three orders of magnitude between the binding affinity of NVP for RT in the presence or absence of primer/template DNA. To investigate the relationship between conformation and ligand binding, we evaluated the use of methionine NMR probes positioned near the tip of the fingers or thumb subdomains. Such probes would be expected to be sensitive to changes in the local environment depending on the fractions of open and closed RT. Comparisons of the NMR spectra of three conservative mutations, I63M, L74M, and L289M, indicated that M63 showed the greatest shift sensitivity to the addition of NVP. The exchange kinetics of the M63 resonance are fast on the chemical shift timescale, but become slow in the presence of NVP due to the slow binding of RT with the inhibitor. The simplest model consistent with this behavior involves a rapid open/closed equilibrium coupled with a slow interaction of the inhibitor with the open conformation. Studies of RT in the presence of both NVP and MgATP indicate a strong negative cooperativity. Binding of MgATP reduces the fraction of RT bound to NVP, as indicated by the intensity of the NVP-perturbed M230 resonance, and enhances the dissociation rate constant of the NVP, resulting in an increase of the open/closed interconversion rate, so that the M63 resonance moves into the fast/intermediate-exchange regime. Protein-mediated interactions appear to explain most of the affinity variation of NVP for RT. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

High Rates of Baseline Drug Resistance and Virologic Failure Among ART-naive HIV-infected Children in Mali.

PubMed

Crowell, Claudia S; Maiga, Almoustapha I; Sylla, Mariam; Taiwo, Babafemi; Kone, Niaboula; Oron, Assaf P; Murphy, Robert L; Marcelin, Anne-Geneviève; Traore, Ban; Fofana, Djeneba B; Peytavin, Gilles; Chadwick, Ellen G

2017-11-01

Limited data exist on drug resistance and antiretroviral treatment (ART) outcomes in HIV-1-infected children in West Africa. We determined the prevalence of baseline resistance and correlates of virologic failure (VF) in a cohort of ART-naive HIV-1-infected children <10 years of age initiating ART in Mali. Reverse transcriptase and protease genes were sequenced at baseline (before ART) and at 6 months. Resistance was defined according to the Stanford HIV Genotypic Resistance database. VF was defined as viral load ≥1000 copies/mL after 6 months of ART. Logistic regression was used to evaluate factors associated with VF or death >1 month after enrollment. Post hoc, antiretroviral concentrations were assayed on baseline samples of participants with baseline resistance. One-hundred twenty children with a median age 2.6 years (interquartile range: 1.6-5.0) were included. Eighty-eight percent reported no prevention of mother-to-child transmission exposure. At baseline, 27 (23%), 4 (3%) and none had non-nucleoside reverse transcriptase inhibitor (NNRTI), nucleoside reverse transcriptase inhibitor or protease inhibitor resistance, respectively. Thirty-nine (33%) developed VF and 4 died >1 month post-ART initiation. In multivariable analyses, poor adherence [odds ratio (OR): 6.1, P = 0.001], baseline NNRTI resistance among children receiving NNRTI-based ART (OR: 22.9, P < 0.001) and protease inhibitor-based ART initiation among children without baseline NNRTI resistance (OR: 5.8, P = 0.018) were significantly associated with VF/death. Ten (38%) with baseline resistance had detectable levels of nevirapine or efavirenz at baseline; 7 were currently breastfeeding, but only 2 reported maternal antiretroviral use. Baseline NNRTI resistance was common in children without reported NNRTI exposure and was associated with increased risk of treatment failure. Detectable NNRTI concentrations were present despite few reports of maternal/infant antiretroviral use.

HIV-1 transmitted drug resistance and genetic diversity among patients from Piauí State, Northeast Brazil.

PubMed

Moura, Maria Edileuza Soares; da Guarda Reis, Mônica Nogueira; Lima, Yanna Andressa Ramos; Eulálio, Kelsen Dantas; Cardoso, Ludimila Paula Vaz; Stefani, Mariane Martins Araújo

2015-05-01

HIV-1 transmitted-drug-resistance and genetic diversity are dynamic and may differ in distinct locations/risk groups. In Brazil, increased AIDS incidence and related mortality have been detected in the Northeast region, differently from the epicenter in the Southeast. This cross-sectional study describes transmitted-dru- resistance and HIV-1 subtypes in protease/PR and reverse transcriptase/RT regions among antiretroviral naïve patients from Piauí State, Northeast Brazil. Among 96 patients recruited 89 (92.7%) had HIV-1 PR/RT regions sequenced: 44 females and 45 males, 22 self-declared as men who have sex with men. Transmitted-drug-resistance was investigated by CPR tool (Stanford HIV-1 Drug Resistance/SDRM). HIV-1 subtypes were assigned by REGA and phylogenetic inference. Overall, transmitted-drug-resistance rate was 11.2% (10/89; CI 95%: 5.8-19.1%); 22.7% among men who have sex with men (5/22; CI 95%: 8.8-43.4%), 10% in heterosexual men (2/20; CI 95%: 1.7-29.3%) and 6.8% in women (3/44; CI 95%: 1.8-17.4%). Singleton mutations to protease-inhibitor/PI, nucleoside-reverse-transcriptase-inhibitor/NRTI or non-nucleoside-reverse-transcriptase-inhibitor/NNRTI predominated (8/10): PI mutations (M46L, V82F, L90M); NRTI mutations (M41L, D67N) and NNRTI mutations (K103N/S). Dual class resistance mutations to NRTI and NNRTI were observed: T215L (NRTI), Y188L (NNRTI) and T215N (NRTI), F227L (NNRTI). Subtype B prevailed (86.6%; 77/89), followed by subtype F1 (1.1%, 1/89) and subtype C (1.1%, 1/89). B/F1 and B/C intersubtype recombinants represented 11.2% (10/89). In Piauí State extensive testing of incidence and transmitted-drug-resistance in all populations with risk behaviors may help control AIDS epidemic locally. © 2015 Wiley Periodicals, Inc.

Novel Method for Simultaneous Quantification of Phenotypic Resistance to Maturation, Protease, Reverse Transcriptase, and Integrase HIV Inhibitors Based on 3′Gag(p2/p7/p1/p6)/PR/RT/INT-Recombinant Viruses: a Useful Tool in the Multitarget Era of Antiretroviral Therapy▿†

PubMed Central

Weber, Jan; Vazquez, Ana C.; Winner, Dane; Rose, Justine D.; Wylie, Doug; Rhea, Ariel M.; Henry, Kenneth; Pappas, Jennifer; Wright, Alison; Mohamed, Nizar; Gibson, Richard; Rodriguez, Benigno; Soriano, Vicente; King, Kevin; Arts, Eric J.; Olivo, Paul D.; Quiñones-Mateu, Miguel E.

2011-01-01

Twenty-six antiretroviral drugs (ARVs), targeting five different steps in the life cycle of the human immunodeficiency virus type 1 (HIV-1), have been approved for the treatment of HIV-1 infection. Accordingly, HIV-1 phenotypic assays based on common cloning technology currently employ three, or possibly four, different recombinant viruses. Here, we describe a system to assess HIV-1 resistance to all drugs targeting the three viral enzymes as well as viral assembly using a single patient-derived, chimeric virus. Patient-derived p2-INT (gag-p2/NCp7/p1/p6/pol-PR/RT/IN) products were PCR amplified as a single fragment (3,428 bp) or two overlapping fragments (1,657 bp and 2,002 bp) and then recombined into a vector containing a near-full-length HIV-1 genome with the Saccharomyces cerevisiae uracil biosynthesis gene (URA3) replacing the 3,428 bp p2-INT segment (Dudley et al., Biotechniques 46:458–467, 2009). P2-INT-recombinant viruses were employed in drug susceptibility assays to test the activity of protease (PI), nucleoside/nucleotide reverse transcriptase (NRTI), nonnucleoside reverse transcriptase (NNRTI), and integrase strand-transfer (INSTI) inhibitors. Using a single standardized test (ViralARTS HIV), this new technology permits the rapid and automated quantification of phenotypic resistance for all known and candidate antiretroviral drugs targeting all viral enzymes (PR, RT, including polymerase and RNase H activities, and IN), some of the current and potential assembly inhibitors, and any drug targeting Pol or Gag precursor cleavage sites (relevant for PI and maturation inhibitors) This novel assay may be instrumental (i) in the development and clinical assessment of novel ARV drugs and (ii) to monitor patients failing prior complex treatment regimens. PMID:21628544

High Levels of Transmitted HIV Drug Resistance in a Study in Papua New Guinea.

PubMed

Lavu, Evelyn; Kave, Ellan; Mosoro, Euodia; Markby, Jessica; Aleksic, Eman; Gare, Janet; Elsum, Imogen A; Nano, Gideon; Kaima, Petronia; Dala, Nick; Gurung, Anup; Bertagnolio, Silvia; Crowe, Suzanne M; Myatt, Mark; Hearps, Anna C; Jordan, Michael R

2017-01-01

Papua New Guinea is a Pacific Island nation of 7.3 million people with an estimated HIV prevalence of 0.8%. ART initiation and monitoring are guided by clinical staging and CD4 cell counts, when available. Little is known about levels of transmitted HIV drug resistance in recently infected individuals in Papua New Guinea. Surveillance of transmitted HIV drug resistance in a total of 123 individuals recently infected with HIV and aged less than 30 years was implemented in Port Moresby (n = 62) and Mount Hagen (n = 61) during the period May 2013-April 2014. HIV drug resistance testing was performed using dried blood spots. Transmitted HIV drug resistance was defined by the presence of one or more drug resistance mutations as defined by the World Health Organization surveillance drug resistance mutations list. The prevalence of non-nucleoside reverse transcriptase inhibitor transmitted HIV drug resistance was 16.1% (95% CI 8.8%-27.4%) and 8.2% (95% CI 3.2%-18.2%) in Port Moresby and Mount Hagen, respectively. The prevalence of nucleoside reverse transcriptase inhibitor transmitted HIV drug resistance was 3.2% (95% CI 0.2%-11.7%) and 3.3% (95% CI 0.2%-11.8%) in Port Moresby and Mount Hagen, respectively. No protease inhibitor transmitted HIV drug resistance was observed. The level of non-nucleoside reverse transcriptase inhibitor drug resistance in antiretroviral drug naïve individuals recently infected with HIV in Port Moresby is amongst the highest reported globally. This alarming level of transmitted HIV drug resistance in a young sexually active population threatens to limit the on-going effective use of NNRTIs as a component of first-line ART in Papua New Guinea. To support the choice of nationally recommended first-line antiretroviral therapy, representative surveillance of HIV drug resistance among antiretroviral therapy initiators in Papua New Guinea should be urgently implemented.

Comparison of reverse transcriptase PCR, reverse transcriptase loop-mediated isothermal amplification, and culture-based assays for Salmonella detection from pork processing environments.

PubMed

Techathuvanan, Chayapa; Draughon, Frances Ann; D'Souza, Doris Helen

2011-02-01

Novel rapid Salmonella detection assays without the need for sophisticated equipment or labor remain in high demand. Real-time reverse transcriptase PCR (RT-PCR) assays, though rapid and sensitive, require expensive thermocyclers, while a novel RT loop-mediated isothermal amplification (RT-LAMP) method requires only a simple water bath. Our objective was to compare the detection sensitivity of Salmonella Typhimurium from the pork processing environment by RT-LAMP, RT-PCR, and culture-based assays. Carcass and surface swabs and carcass rinses were obtained from a local processing plant. Autoclaved carcass rinses (500 ml) were spiked with Salmonella Typhimurium and filtered. Filters were placed in stomacher bags containing tetrathionate broth (TTB) and analyzed with or without 10-h enrichment at 37 °C. Natural swabs were stomached with buffered peptone water, and natural carcass rinses were filtered, preenriched, and further enriched in TTB. Serially-diluted enriched samples were enumerated by spread plating on xylose lysine Tergitol 4 agar. RNA was extracted from 5 ml of enriched TTB with TRIzol. RT-LAMP assay using previously described invA primers was conducted at 62 °C for 90 min in a water bath with visual detection and by gel electrophoresis. SYBR Green I-based-real-time RT-PCR was carried out with invA primers followed by melt temperature analysis. The results of RT-LAMP detection for spiked carcass rinses were comparable to those of RT-PCR and cultural plating, with detection limits of 1 log CFU/ml, although they were obtained significantly faster, within 24 h including preenrichment and enrichment. RT-LAMP showed 4 of 12 rinse samples positive, while RT-PCR showed 1 of 12 rinse samples positive. For swabs, 6 of 27 samples positive by RT-LAMP and 5 of 27 by RT-PCR were obtained. This 1-day RT-LAMP assay shows promise for routine Salmonella screening by the pork industry. Copyright ©, International Association for Food Protection

Transmitted drug resistance in patients with acute/recent HIV infection in Brazil.

PubMed

Ferreira, Ana Cristina G; Coelho, Lara E; Grinsztejn, Eduarda; Jesus, Carlos S de; Guimarães, Monick L; Veloso, Valdiléa G; Grinsztejn, Beatriz; Cardoso, Sandra W

The widespread use of antiretroviral therapy increased the transmission of antiretroviral resistant HIV strains. Antiretroviral therapy initiation during acute/recent HIV infection limits HIV reservoirs and improves immune response in HIV infected individuals. Transmitted drug resistance may jeopardize the early goals of early antiretroviral treatment among acute/recent HIV infected patients. Patients with acute/recent HIV infection who underwent resistance test before antiretroviral treatment initiation were included in this analysis. HIV-1 sequences were obtained using an in house protease/reverse transcriptase genotyping assay. Transmitted drug resistance was identified according to the Stanford HIV Database for Transmitted Drug Resistance Mutations, based on WHO 2009 surveillance list, and HIV-1 subtyping according to Rega HIV-1 subtyping tool. Comparison between patients with and without transmitted drug resistance was made using Kruskal-Wallis and Chi-square tests. Forty-three patients were included, 13 with acute HIV infection and 30 with recent HIV infection. The overall transmitted drug resistance prevalence was 16.3% (95% confidence interval [CI]: 8.1-30.0%). The highest prevalence of resistance (11.6%, 95% CI: 8.1-24.5) was against non-nucleoside reverse transcriptase inhibitors, and K103N was the most frequently identified mutation. The high prevalence of nonnucleoside reverse transcriptase inhibitors resistance indicates that efavirenz-based regimen without prior resistance testing is not ideal for acutely/recently HIV-infected individuals in our setting. In this context, the recent proposal of including integrase inhibitors as a first line regimen in Brazil could be an advantage for the treatment of newly HIV infected individuals. However, it also poses a new challenge, since integrase resistance test is not routinely performed for antiretroviral naive individuals. Further studies on transmitted drug resistance among acutely/recently HIV-infected are needed to inform the predictors of transmitted resistance and the antiretroviral therapy outcomes among these population. Copyright © 2017 Sociedade Brasileira de Infectologia. Published by Elsevier Editora Ltda. All rights reserved.

Evaluation of in vitro anti-Leishmanial activity of some brown, green and red algae from the Persian Gulf.

PubMed

Fouladvand, M; Barazesh, A; Farokhzad, F; Malekizadeh, H; Sartavi, K

2011-06-01

Leishmaniasis is a protozoan parasitic disease which is transmitted by the female Phlebotomus sand fly and is prevalent in four continents.The first-choice treatment for the leishmaniasis is pentavalent antimonials, which are potentially toxic and often ineffective and use of them exhibit therapeutic failure. These pharmaceutical problems point towards the need to develop novel chemotherapeutic agents. Seaweeds are considered as source of bioactive metabolites characterized by a broad spectrum of biological activities. In this experimental study, cold and hot water crude extracts of four species of green, brown and red marine algae "Caulerpa sertularioides, Gracilaria corticata, Gracillaria salicornia and Sargassum oligocystum" collected along the Bushehr coast of the Persian Gulf (southwest of Iran), prepared and their in vitro activities against Leishmania major promastigote were evaluated by using the MTT assay test. The cold and hot water crude extracts of four algae species exhibited different anti-Leishmanial activities. The minimum inhibitory concentration of hot water extracts calculated as IC50 was as follows: Caulerpa sertularioides (IC50 < or =85 microg/ml), Gracilaria corticata (IC50 < or =38 microg/ml), Gracillaria salicornia (IC50 < or =46 microg/ml) and Sargassum oligocystum (IC(50)9 < or =78 microg/ml, while these values for cold water extracts were (IC50 >125 microg/ml) for Caulerpa Sertularioides (IC50 >65 microg/ml) for Gracilaria corticata (IC50 >74 microg/ml) for Gracilaria salicornia and (IC50 >105 microg/ml) for Sargassum oligocystum, IC50 values for reference drug (Amphotericin B) was (0.16-0.2 microg/ml). According to the results, inhibitory effects of the crude extracts from these four species algae specially hot water crude extracts from "Gracilaria corticata, Gracillaria salicornia and Sargassum oligocystum" are significant and in accordance with other studies that has been done on different algae species. So these results are sufficiently promising to be followed with further studies on isolation and characterization of pure compounds from these algae species as well as in vivo experiments, a work that is already under way in our laboratory.

ITC commentary on the prediction of digoxin clinical drug-drug interactions from in vitro transporter assays.

PubMed

Lee, C A; Kalvass, J C; Galetin, A; Zamek-Gliszczynski, M J

2014-09-01

The "P-glycoprotein" IC50 working group reported an 18- to 796-fold interlaboratory range in digoxin transport IC50 (inhibitor concentration achieving 50% of maximal inhibition), raising concerns about the predictability of clinical transporter-based drug-drug interactions (DDIs) from in vitro data. This Commentary describes complexities of digoxin transport, which involve both uptake and efflux processes. We caution against attributing digoxin transport IC50 specifically to P-glycoprotein (P-gp) or extending this composite uptake/efflux IC50 variability to individual transporters. Clinical digoxin interaction studies should be interpreted as evaluation of digoxin safety, not P-gp DDIs.

Biotransformation of a potent anabolic steroid, mibolerone, with Cunninghamella blakesleeana, C. echinulata, and Macrophomina phaseolina, and biological activity evaluation of its metabolites.

PubMed

Siddiqui, Mahwish; Ahmad, Malik Shoaib; Wahab, Atia-Tul-; Yousuf, Sammer; Fatima, Narjis; Naveed Shaikh, Nimra; Rahman, Atta-Ur-; Choudhary, M Iqbal

2017-01-01

Seven metabolites were obtained from the microbial transformation of anabolic-androgenic steroid mibolerone (1) with Cunninghamella blakesleeana, C. echinulata, and Macrophomina phaseolina. Their structures were determined as 10β,17β-dihydroxy-7α,17α-dimethylestr-4-en-3-one (2), 6β,17β-dihydroxy-7α,17α-dimethylestr-4-en-3-one (3), 6β,10β,17β-trihydroxy-7α,17α-dimethylestr-4-en-3-one (4), 11β,17β-dihydroxy-(20-hydroxymethyl)-7α,17α-dimethylestr-4-en-3-one (5), 1α,17β-dihydroxy-7α,17α-dimethylestr-4-en-3-one (6), 1α,11β,17β-trihydroxy-7α,17α-dimethylestr-4-en-3-one (7), and 11β,17β-dihydroxy-7α,17α-dimethylestr-4-en-3-one (8), on the basis of spectroscopic studies. All metabolites, except 8, were identified as new compounds. This study indicates that C. blakesleeana, and C. echinulata are able to catalyze hydroxylation at allylic positions, while M. phaseolina can catalyze hydroxylation of CH2 and CH3 groups of substrate 1. Mibolerone (1) was found to be a moderate inhibitor of β-glucuronidase enzyme (IC50 = 42.98 ± 1.24 μM) during random biological screening, while its metabolites 2-4, and 8 were found to be inactive. Mibolerone (1) was also found to be significantly active against Leishmania major promastigotes (IC50 = 29.64 ± 0.88 μM). Its transformed products 3 (IC50 = 79.09 ± 0.06 μM), and 8 (IC50 = 70.09 ± 0.05 μM) showed a weak leishmanicidal activity, while 2 and 4 were found to be inactive. In addition, substrate 1 (IC50 = 35.7 ± 4.46 μM), and its metabolite 8 (IC50 = 34.16 ± 5.3 μM) exhibited potent cytotoxicity against HeLa cancer cell line (human cervical carcinoma). Metabolite 2 (IC50 = 46.5 ± 5.4 μM) also showed a significant cytotoxicity, while 3 (IC50 = 107.8 ± 4.0 μM) and 4 (IC50 = 152.5 ± 2.15 μM) showed weak cytotoxicity against HeLa cancer cell line. Compound 1 (IC50 = 46.3 ± 11.7 μM), and its transformed products 2 (IC50 = 43.3 ± 7.7 μM), 3 (IC50 = 65.6 ± 2.5 μM), and 4 (IC50 = 89.4 ± 2.7 μM) were also found to be moderately toxic to 3T3 cell line (mouse fibroblast). Interestingly, metabolite 8 showed no cytotoxicity against 3T3 cell line. Compounds 1-4, and 8 were also evaluated for inhibition of tyrosinase, carbonic anhydrase, and α-glucosidase enzymes, and all were found to be inactive.

In vitro anti-plasmodial activity of some traditionally used medicinal plants against Plasmodium falciparum.

PubMed

Venkatesalu, V; Gopalan, N; Pillai, C R; Singh, Vineeta; Chandrasekaran, M; Senthilkumar, A; Chandramouli, N

2012-07-01

The anti-plasmodial activity of different solvent extracts of Adhatoda vasica (root), Caesalpinia pulcherrima (leaf), Carica papaya (pulp), Erythroxylum monogynum (leaf), Lantana camara (whole plant), Ocimum sanctum (root) and Phyllanthus niruri (whole plant) were studied against Plasmodium falciparum. Of the 35 extracts tested, seven extracts showed good anti-plasmodial activity. Methanol extract of C. pulcherrima showed the lowest IC50 value (10.96 μg/mL) followed by methanol extract of A. vasica (IC(50)=11.1 μg/mL), chloroform extract of O. sanctum (IC(50)=11.47 μg/mL), methanol extract of E. monogynum (IC(50)=12.23 μg/mL), acetone extract of C. pulcherrima (IC(50)=12.49 μg/mL), methanol extract of O. sanctum and acetone extract of A. vasica (IC(50)=14.04 μg/mL). The results of the present study justify the use of these medicinal plants in traditional practice, and also, a further study on the isolation of anti-plasmodial molecules from their active crude extracts is in progress.

Membrane depolarization-induced RhoA/Rho-associated kinase activation and sustained contraction of rat caudal arterial smooth muscle involves genistein-sensitive tyrosine phosphorylation

PubMed Central

Mita, Mitsuo; Tanaka, Hitoshi; Yanagihara, Hayato; Nakagawa, Jun-ichi; Hishinuma, Shigeru; Sutherland, Cindy; Walsh, Michael P.; Shoji, Masaru

2013-01-01

Rho-associated kinase (ROK) activation plays an important role in K+-induced contraction of rat caudal arterial smooth muscle (Mita et al., Biochem J. 2002; 364: 431–40). The present study investigated a potential role for tyrosine kinase activity in K+-induced RhoA activation and contraction. The non-selective tyrosine kinase inhibitor genistein, but not the src family tyrosine kinase inhibitor PP2, inhibited K+-induced sustained contraction (IC50 = 11.3 ± 2.4 µM). Genistein (10 µM) inhibited the K+-induced increase in myosin light chain (LC20) phosphorylation without affecting the Ca2+ transient. The tyrosine phosphatase inhibitor vanadate induced contraction that was reversed by genistein (IC50 = 6.5 ± 2.3 µM) and the ROK inhibitor Y-27632 (IC50 = 0.27 ± 0.04 µM). Vanadate also increased LC20 phosphorylation in a genistein- and Y-27632-dependent manner. K+ stimulation induced translocation of RhoA to the membrane, which was inhibited by genistein. Phosphorylation of MYPT1 (myosin-targeting subunit of myosin light chain phosphatase) was significantly increased at Thr855 and Thr697 by K+ stimulation in a genistein- and Y-27632-sensitive manner. Finally, K+ stimulation induced genistein-sensitive tyrosine phosphorylation of proteins of ∼55, 70 and 113 kDa. We conclude that a genistein-sensitive tyrosine kinase, activated by the membrane depolarization-induced increase in [Ca2+]i, is involved in the RhoA/ROK activation and sustained contraction induced by K+. Ca2+ sensitization, myosin light chain phosphatase, RhoA, Rho-associated kinase, tyrosine kinase PMID:24133693