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A series of hitherto unknown 3′-α-[1,2,3]-substituted triazolo-2′,3′-dideoxypyrimidine nucleoside analogues of the anti-HIV 3′-azido-3′-deoxythymidine (AZT) were synthesized through catalyzed alkyne-azide 1,3-dipolar cycloaddition (Huisgen reaction). Those 3′-[1,2,3]-triazolo analogues bearing an azido alkyl chain were evaluated for their anti-HIV activity against HIV-1 in primary human lymphocytes as well as for their cytotoxicity in different cells. None of them inhibit HIV replication (EC(50) > 20 μM); two of them were converted to their triphosphate form to evaluate their HIV-RT inhibition.

Nucleoside reverse transcriptase inhibitors (NRTI) require intracellular phosphorylation, which involves multiple enzymatic steps to inhibit the human immunodeficiency virus type 1 (HIV-1). NRTI-triphosphates (NRTI-TP) compete with endogenous 2'-deoxyribonucleosides-5'-triphosphates (dNTP) for incorporation by the HIV-1 reverse transcriptase (RT). Thus, a highly sensitive analytical methodology capable of quantifying at the low femtomoles/10(6) cells level was necessary to understand the intracellular metabolism and antiviral activity of NRTIs in human peripheral blood mononuclear (PBM) cells and in macrophages. A novel, rapid, and a reproducible ion-pair chromatography-tandem mass spectrometry (MS/MS) method was developed to simultaneously quantify the intracellular phosphorylated metabolites of abacavir, emtricitabine, tenofovir disoproxil fumarate, amdoxovir, and zidovudine, as well as four natural endogenous dNTP. Positive or negative electrospray ionization was chosen with specific MS/MS transitions for improved selectivity on all the compounds studied. The sample preparation, the ion-pair reagent concentration, and buffer composition were optimized, resulting in the simultaneous quantification of 13 different nucleotides in a total run time of 30 min. This novel method demonstrated optimal sensitivity (limit of detection 1-10 nM for various analytes), specificity, and reproducibility to successfully measure NRTI-TP and dNTP in human PBM cells and macrophages.

Entecavir (ETV) is a potent antiviral nucleoside analogue that is used to treat hepatitis B virus (HBV) infection. Recent clinical studies have demonstrated that ETV is also active against the human immunodeficiency virus type 1 (HIV-1). Unlike all approved nucleoside analogue reverse transcriptase RT) inhibitors (NRTIs), ETV contains a 3′-hydroxyl group that allows further nucleotide incorporation events to occur. Thus, the mechanism of inhibition probably differs from classic chain termination. Here, we show that the incorporated ETV-monophosphate (MP) can interfere with three distinct stages of DNA synthesis. First, incorporation of the next nucleotide at position n + 1 following ETV-MP is compromised, although DNA synthesis eventually continues. Second, strong pausing at position n + 3 suggests a long range effect, referred to as “delayed chain-termination.” Third, the incorporated ETV-MP can also act as a “base pair confounder” during synthesis of the second DNA strand, when the RT enzyme needs to pass the inhibitor in the template. Enzyme kinetics revealed that delayed chain termination is the dominant mechanism of action. High resolution foot-printing experiments suggest that the incorporated ETV-MP “repels” the 3′-end of the primer from the active site of HIV-1 RT, which, in turn, diminishes incorporation of the natural nucleotide substrate at position n + 4. Most importantly, delayed chain termination protects ETV-MP from phosphorolytic excision, which represents a major resistance mechanism for approved NRTIs. Collectively, these findings provide a rationale and important tools for the development of novel, more potent delayed chain terminators as anti-HIV agents.

The novel 2'-deoxyguanosine analog Entecavir (ETV) is a potent inhibitor of hepatitis B virus (HBV) replication and is recommended for treatment in human immunodeficiency virus type 1 (HIV-1) and HBV-co-infected patients because it had been reported that ETV is HBV-specific. Recent clinical observations, however, have suggested that ETV may indeed demonstrate anti-HIV-1 activity. To investigate this question at a molecular level, kinetic studies were used to examine the interaction of 5'-triphosphate form of ETV with wild type (WT) HIV-1 reverse transcriptase (RT) and the nucleoside reverse transcriptase inhibitor-resistant mutation M184V. Using single turnover kinetic assays, we found that HIV-1 WT RT and M184V RT could use the activated ETV triphosphate metabolite as a substrate for incorporation. The mutant displayed a slower incorporation rate, a lower binding affinity, and a lower incorporation efficiency with the 5'-triphosphate form of ETV compared with WT RT, suggesting a kinetic basis for resistance. Our results are supported by cell-based assays in primary human lymphocytes that show inhibition of WT HIV-1 replication by ETV and decreased susceptibility of the HIV-1 containing the M184V mutation. This study has important therapeutic implications as it establishes ETV as an inhibitor for HIV-1 RT and illustrates the mechanism of resistance by the M184V mutant.

F-theory, as Theory of Everything is compactified on Calabi-Yau threefolds or fourfolds. Using toric approximation of Batyrev and mirror symmetry of Calabi-Yau manifolds it is possible to present Calabi-Yau in the form of dual integer polyhedra. With the help of Gelfand, Zelevinsky, Kapranov algorithm were calculated the numbers of BPS-states in F-theory, and by application of Tate algorithm were determined the enhanced symmetries. As the result, any integral dual polyhedron representing a Calabi-Yau manifold, is characterized by its own set of topological invariants - the numbers of BPS states, whose central charges are classified by enhanced symmetries., 8 pages, 1 figure, iopams.sty

The state of natural-technogenic and environmental safety of Kyiv is extremely complicated. The natural component of the hazard is caused, primarily, by the complex relief. Thus, among natural threats and risks are landslide processes, flooding, complex meteorological phenomena, etc. The relatively small territory of the city is oversaturated with complex engineering structures and production (radiation, chemical, hydrodynamic, explosion fire hazard) and has one of the highest population density. At the risk of emergency situation (ES) there will be a few million people in the affected area. According to the State Service of Emergencies of Ukraine, during 2014 the death toll as a result of emergencies accounted for 3 people and 33 people suffered. In 2013 there were 7 ES, the number of sufferers and dead were 95 and 3 people, respectively.

Amdoxovir, currently in Phase II clinical trials, is rapidly converted to 9-(β-D-1,3-dioxolan-4-yl)guanine (DXG) by adenosine deaminase in vitro and in humans. The cellular pharmacology of DXG in primary human lymphocytes, including dose-response relationships, intracellular half-life of DXG triphosphate (DXG-TP), and combination studies were determined. DXG produced high levels of DXG-TP with a long half-life (16 h) in activated human peripheral blood mononuclear cells. Since zidovudine (ZDV) and DXG select for different resistance mutations, co-formulation of the these two drugs is an attractive proposition. A combination study between DXG and ZDV showed no reduction of DXG-TP or ZDV-TP. Taken together, these results suggest that an appropriately designed DXG prodrug could be given once a day and that co-formulation with ZDV might be a possibility.

β-d-Dioxolane-thymine (D-DOT) has potent and selective in vitro activity against several clinically important resistant human immunodeficiency virus (HIV) mutants and is in advanced preclinical development. Therefore, the single-dose intravenous and oral pharmacokinetics of D-DOT were studied with three rhesus monkeys. The pharmacokinetic profiles of D-DOT in serum and urine were adequately described by a two-compartment open pharmacokinetic model. D-DOT was rapidly and almost completely absorbed (absorption rate constant = 2.7 h−1; fraction of oral dose absorbed = 0.82 to 1.06). The average serum beta half-life was 2.16 h. The average central and steady-state volumes of distributions were 0.52 and 1.02 liter/kg of body weight, respectively, and the average systemic and renal clearance values were 0.36 liter/h/kg and 0.18 liter/h/kg. Four or eight percent of administered D-DOT was eliminated in the urine as glucuronide within 8 h after intravenous or oral administration, respectively. D-DOT reached levels in the cerebrospinal fluid in excess of 10 to 20 times the median effective concentration for wild-type HIV and resistant mutants. The potent antiretroviral activity of D-DOT against a lamivudine- and zidovudine-resistant HIV-1 mutant, together with an excellent pharmacokinetic profile for rhesus monkeys, suggest that further development is warranted.

F-theory has been receiving more attention in the past few years because its rich structure allows to solve many problems of the Standard Model and Grand Unification Theory. This theory is also important because of the necessity to solve the problem of vacuum stability. A simpler solution of F-theory is used to describe the Type IIB string theory. For the classification of D-brane charges in superstring theory of Type IIB is applied K-theory. This approach provides an access to gauge fields connected with vector bundles, classified by K-theory. This technique implements the resolution of issues related to the structure of scales and hierarchies, the gauge group and charged matter content., В последние несколько лет Ф-теория привлекает большее внимание благодаря ее богатой структуре, позволяющей решить многие проблемы Стандартной Модели и Теории Великого Объединения. Эта теория также важна из-за необходимости решить проблему стабильности вакуума. Более простая реализация Ф-теории используется для описания струнной теории типа IIB. Для классификации зарядов D-бран в суперструнной теории типа IIB применяется К-теория. Этот подход обеспечивает выход на калибровочные поля, связанные с векторными расслоениями, классифицированными К-теорией. Эта техника реализует решение вопросов, связанных со структурой масштабов и иерархий, калибровочной группой и составом заряженных полей., Останні декілька років Ф-теорія привертає більшу увагу завдяки її багатій структурі, що дозволяє вирішити багато проблем Стандартної Моделі і Теорії Великого Об'єднання. Ця теорія також важлива через необхідність вирішити проблему стабільності вакууму. Більш проста реалізація Ф-теорії використовується для опису струнної теорії типу IIB. Для класифікації зарядів D-бран в суперструнній теорії типу IIB застосовується К-теорія. Цей підхід забезпечує вихід на калібрувальні поля, пов'язані з векторними розшаруваннями, класифікованими К-теорією. Ця техніка реалізує вирішення питань, пов'язаних зі структурою масштабів та ієрархій, калібрувальної групою і складом заряджених полів.

Search for supersymmetry is carried out in the framework of the Minimal Supersymmetric Standard Model (MSSM). Using the software programs SOFTSUSY and PROSPINO, the mass spectrum and the production cross-sections of superpartners are calculated. The results obtained are of importance for searching the new physics at the LHC., 11 pages, 2 figures

The article examines prerequisites for the formation of the global environmental safety as an integral part of international relations and politics against the background of the long-term ecological crisis. Features of the global environmental safety and levels of its operation on a territorial basis are singled out and grounded. Attention is focused on transboundary character of the manifestation of most environmental threats and hazards, making it impossible for countries to overcome the consequences on their own. Emphasized are global threats and hazards that will determine areas of cooperation in the global environmental safety in the near future. Parity basis and principles of formation of global ecologically safe space are outlined. Considering the world experience of the implementation of forms and methods of economical use of natural resources and observance of safety of existence, directions of strategic planning of national environmental safety are suggested. Розкриваються передумови становлення глобальної екологічної безпеки як невід’ємної частини міжнародних відносин та політики на фоні довготривалої екологічної кризи. Виділяються та обґрунтовуються характерні ознаки глобальної екологічної безпеки та рівні її функціонування за територіальним принципом. Акцентується увага на транскордонності прояву більшості екологічних загроз та небезпек, що унеможливлює подолання наслідків державами самостійно. Виділено глобальні загрози та небезпеки, що визначатимуть у найближчій перспективі напрями співпраці у світовій екологічній безпеці. Окреслюються паритетні засади та принципи формування глобального екологобезпечного простору. Виходячи із світового досвіду форм і методів ощадливого використання природних ресурсів та дотримання безпеки існування, запропоновано напрями стратегічного планування національної екологічної безпеки.

The analysis of recent experimental data received from LHC (CMS) restricts the range of MSSM parameters. Using computer programs SOFTSUSY, SDECAY the mass spectrum and partial width of superpatners are calculated. With the help of computer program PROSPINO the calculations of the next-to-leading order (NLO) corrections to the production cross sections of superpartners are made. With the help of computer program PYTHIA the NLO corrections on differential distributions of pT and η for squarks and gluino are represented. Анализ последних экспериментальных данных, полученных из БАК (КМС), ограничил пространство МССМ параметров. С помощью компьютерных программ SOFTSUSY, SDECAY посчитаны спектры масс и ширины распадов суперчастиц. Проведены расчеты next-to-leading order (NLO) поправок к поперечному сечению образования суперчастиц с помощью компьютерной программы PROSPINO. Представлены NLO поправки к дифференциальному сечению распределения по pT и η для скварков и глюино. Аналiз останнiх експериментальних даних отриманих на ВАК (КМС) звузив простiр МССМ параметрiв. За допомогою комп'ютерних програм SOFTSUSY, SDECAY розраховано спектри мас i ширини розпадiв суперчастинок. Проведено розрахунки next-to-leading order (NLO) поправок до поперечного перерiзу утворення суперчастiнок за допомогою комп'ютерної програми PROSPINO. Представлено NLO поправки до диференцiйного перерiзу розподiлу по pT i η для скваркiв i глюiно.

Searches for SUSY with R-parity conservation are connected with LSP particle - the best dark matter candidate. Using the new Minimal Supersymmetric Standard Model (MSSM) parameters received from recent experimental data at the LHC (CMS) it is possible to calculate the mass spectrum, partial width and production cross sections of superpatners. In the context of MSSM model histograms of mass distributions for superpartners ~qR and ~g are constructed. Поиски SUSY с сохранением R-четности связаны с LSP-частицей – лучшим кандидатом темной материи. Используя новые MSSM параметры, полученные из последних экспериментальных данных на LHC(CMS), можно посчитать массы, ширины распадов и сечения рождения суперчастиц. В контексте MSSM модели построены гистрограммы распределения масс суперчастиц ~qR и ~q. Пошуки SUSY iз збереженням R-порностi пов'язанi з LSP-частинкою кращим кандидатом темної матерiї. Викормстання нових MSSM параметрiв, отриманих iз останнiх експериментальних даних на LHC(CMS), дає можливiсть розрахувати маси, ширини розпадiв i перерiзи породження суперчастинок. В контекстi MSSM моделi побудованi гiстограми розподiлу мас суперчастинок ~qR i ~g .

We study D-branes on Calabi-Yau threefolds, which are realized through the blowing up the singularity of orbifold. This D-branes are represented as sheaves, which can be stable or unstable, what is connected with the transition in the Teichm$\ddot{u}$ller space. Using the derived category of McKay quiver representations, which describe D-branes as quivers and open superstrings between them by Ext groups, we can represent Higgs multiplets by the moduli space of an open superstring, connecting two McKay quivers. Through the equivalence between the derived category of coherent sheaves and triangulated category of distinguished triangles over the abelian category of McKay quivers we can associate D-branes with quivers or with sheaves, defined on Calabi-Yau. After the dimensional reduction of the ten-dimensional space-time we can receive matter content of the four-dimensional space-time. Thus, a higher-dimensional breaking mechanism is associated with four-dimensional GUT Higgs multiplets and symmetry breaking higgs mechanism., Comment: 6 pages, 4 figures, jheppub.sty. arXiv admin note: text overlap with arXiv:hep-th/0403166 by other authors

7-Deazapurines are known to possess broad antiviral activity, however the 2′-C-methylguanosine analogue displays poor cell permeation and limited phosphorylation, thus is not an efficient inhibitor of hepatitis C virus (HCV) replication. We previously reported the 6-O-methyl entity as a prodrug moiety to increase liphophilicity of guanine nucleosides and the ProTide approach applied to 2′-C-methyl-6-O-methylguanosine has lead to potent HCV inhibitors now in clinical trials. In this Letter, we report the synthesis and biological evaluation of 2′-C-methyl-6-O-methyl-7-deaza guanosine and ProTide derivatives. In contrast to prior studies, removal of the N-7 of the nucleobase entirely negates anti-HCV activity compared to the 2′-C-methyl-6-O-methylguanosine analogues. To understand better this significant loss of activity, enzymatic assays and molecular modeling were carried out and suggested 2′-C-methyl-6-O-methyl-7-deaza guanosine and related ProTides do not act as efficient prodrugs of the free nucleotide, in marked contrast to the case of the parent guanine analogue.

A series of hitherto unknown 3′-α-[1,2,3]-substituted triazolo-2′,3′-dideoxypyrimidine nucleoside analogues of the anti-HIV 3′-azido-3′-deoxythymidine (AZT) were synthesized through catalyzed alkyne-azide 1,3-dipolar cycloaddition (Huisgen reaction). Those 3′-[1,2,3]-triazolo analogues bearing an azido alkyl chain were evaluated for their anti-HIV activity against HIV-1 in primary human lymphocytes as well as for their cytotoxicity in different cells. None of them inhibit HIV replication (EC50 > 20 μM); two of them were converted to their triphosphate form to evaluate their HIV-RT inhibition.

We herein report phosphorodiamidates as a significant new phosphate prodrug motif. Sixty-seven phosphorodiamidates are reported of two 6-O-alkyl 2′-C-methyl guanosines, with significant variation in the diamidate structure. Both symmetrical and asymmetric phosphorodiamidates are reported, derived from various esterified amino acids, both d and l, and also from various simple amines. All of the compounds were evaluated versus hepatitis C virus in replicon assay, and nanomolar activity levels were observed. Many compounds were noncytotoxic at 100 μM, leading to high antiviral selectivities. The agents are stable in acidic, neutral, and moderately basic media and in selected biological media but show efficient processing by carboxypeptidases and efficiently yield the free nucleoside monophosphate in cells. On the basis of in vitro data, eight leads were selected for additional in vivo evaluation, with the intent of selecting one candidate for progression toward clinical studies. This phosphorodiamidate prodrug method may have broad application outside of HCV and antivirals as it offers many of the advantages of phosphoramidate ProTides but without the chirality issues present in most cases.

Based on the promising drug resistance profile and potent anti-HIV activity of beta-d-3'-azido-2',3'-dideoxyguanosine, a series of purine modified nucleosides were synthesized by a chemical transglycosylation reaction and evaluated for their antiviral activity, cytotoxicity, and intracellular metabolism. Among the synthesized compounds, several show potent and selective anti-HIV activity in primary lymphocytes.

Detailed structural and biochemical studies with the human cytomegalovirus (HCMV UL54) DNA polymerase are hampered by difficulties to obtain this enzyme in large quantities. The crystal structure of the related RB69 DNA polymerase (gp43) is often used as a model system to explain mechanisms of inhibition of DNA synthesis and drug resistance. However, here we demonstrate that gp43 is approximately 400-fold less sensitive to the pyrophosphate analog foscarnet, when compared with UL54. The RB69 enzyme is also able to discriminate against the nucleotide analog inhibitor acyclovir. In contrast, the HCMV polymerase is able to incorporate this compound with similar efficiency as observed with its natural counterpart. In an attempt to identify major determinants for drug activity, we replaced critical regions of the nucleotide-binding site of gp43 with equivalent regions of the HCMV enzyme. We show that chimeric gp43-UL54 enzymes that contain residues of helix N and helix P of UL54 are resensitized against foscarnet and acyclovir. Changing a region of three amino acids of helix N showed the strongest effects, and changes of two segments of three amino acids in helix P further contributed to the reversal of the phenotype. The engineered chimeric enzyme can be produced in large quantities and may therefore be a valuable surrogate system in drug development efforts. This system may likewise be used for detailed structural and biochemical studies on mechanisms associated with drug action and resistance.

It has recently been demonstrated that the anti-herpetic drug acyclovir (ACV) also displays antiviral activity against the human immunodeficiency virus type 1 (HIV-1). The triphosphate form of ACV is accepted by HIV-1 reverse transcriptase (RT), and subsequent incorporation leads to classical chain termination. Like all approved nucleoside analogue RT inhibitors (NRTIs), the selective pressure of ACV is associated with the emergence of resistance. The V75I mutation in HIV-1 RT appears to be dominant in this regard. By itself, this mutation is usually not associated with resistance to currently approved NRTIs. Here we studied the underlying biochemical mechanism. We demonstrate that V75I is also selected under the selective pressure of a monophosphorylated prodrug that was designed to bypass the bottleneck in drug activation to the triphosphate form (ACV-TP). Pre-steady-state kinetics reveal that V75I discriminates against the inhibitor at the level of catalysis, whereas binding of the inhibitor remains largely unaffected. The incorporated ACV-monophosphate (ACV-MP) is vulnerable to excision in the presence of the pyrophosphate donor ATP. V75I compromises binding of the next nucleotide that can otherwise provide a certain degree of protection from excision. Collectively, the results of this study suggest that ACV is sensitive to two different resistance pathways, which warrants further investigation regarding the detailed resistance profile of ACV. Such studies will be crucial in assessing the potential clinical utility of ACV and its derivatives in combination with established NRTIs.

A series of 3,9-dihydro-9-oxo-5H-imidazo[1,2-A]purine nucleosides (tricylic nucleosides) were synthesized from 9-[4-alpha-(hydroxymethyl)cyclopent-2-ene-1-alpha-yl]guanine (CBV) 5, (-)-beta-D-(2R,4R)-1,3-dioxolane-guanosine (DXG) 6, 3'-azido-3'-deoxy-guanosine (AZG) 7, and 2'-C-methylguanosine 8. Their in vitro activity against HIV and HCV was evaluated and correlated to their ability to degrade to their purine counterpart.

Superstring theory is applied to construction of the Minimal Supersymmetric Standard Model.

Amdoxovir, currently in Phase II clinical trials, is rapidly converted to 9-(beta-D-1,3-dioxolan-4-yl)guanine (DXG) by adenosine deaminase in vitro and in humans. The cellular pharmacology of DXG in primary human lymphocytes, including dose-response relationships, intracellular half-life of DXG triphosphate (DXG-TP), and combination studies were determined. DXG produced high levels of DXG-TP with a long half-life (16 h) in activated human peripheral blood mononuclear cells. Since zidovudine (ZDV) and DXG select for different resistance mutations, co-formulation of the these two drugs is an attractive proposition. A combination study between DXG and ZDV showed no reduction of DXG-TP or ZDV-TP. Taken together, these results suggest that an appropriately designed DXG prodrug could be given once a day and that co-formulation with ZDV might be a possibility.

β- d -2′-Deoxy-2′-fluoro-2′- C -methylcytidine (PSI-6130) is a potent specific inhibitor of hepatitis C virus (HCV) RNA synthesis in Huh-7 replicon cells. To inhibit the HCV NS5B RNA polymerase, PSI-6130 must be phosphorylated to the 5′-triphosphate form. The phosphorylation of PSI-6130 and inhibition of HCV NS5B were investigated. The phosphorylation of PSI-6130 by recombinant human 2′-deoxycytidine kinase (dCK) and uridine-cytidine kinase 1 (UCK-1) was measured by using a coupled spectrophotometric reaction. PSI-6130 was shown to be a substrate for purified dCK, with a K m of 81 μM and a k cat of 0.007 s −1 , but was not a substrate for UCK-1. PSI-6130 monophosphate (PSI-6130-MP) was efficiently phosphorylated to the diphosphate and subsequently to the triphosphate by recombinant human UMP-CMP kinase and nucleoside diphosphate kinase, respectively. The inhibition of wild-type and mutated (S282T) HCV NS5B RNA polymerases was studied. The steady-state inhibition constant ( K i ) for PSI-6130 triphosphate (PSI-6130-TP) with the wild-type enzyme was 4.3 μM. Similar results were obtained with 2′- C -methyladenosine triphosphate ( K i = 1.5 μM) and 2′- C -methylcytidine triphosphate ( K i = 1.6 μM). NS5B with the S282T mutation, which is known to confer resistance to 2′- C -methyladenosine, was inhibited by PSI-6130-TP as efficiently as the wild type. Incorporation of PSI-6130-MP into RNA catalyzed by purified NS5B RNA polymerase resulted in chain termination.