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Search Results: 1 - 10 of 148395 matches for " Alexander V. Glushakov "
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Contribution of PGE2 EP1 receptor in hemin-induced neurotoxicity
Shekher Mohan,Alexander V. Glushakov,Alexander deCurnou,Sylvain Doré
Frontiers in Molecular Neuroscience , 2013, DOI: 10.3389/fnmol.2013.00031
Abstract: Although hemin-mediated neurotoxicity has been linked to the production of free radicals and glutamate excitotoxicity, the role of the prostaglandin E2 (PGE2)-EP1 receptor remains unclear. Activation of the EP1 receptor in neurons results in increased intracellular calcium levels; therefore, we hypothesize that the blockade of the EP1 receptor reduces hemin neurotoxicity. Using postnatal primary cortical neurons cultured from wild-type (WT) and EP1?/? mice, we investigated the EP1 receptor role in hemin neurotoxicity measured by lactate dehydrogenase (LDH) cell survival assay. Hemin (75 μM) induced greater release of LDH in WT (34.7 ± 4.5%) than in EP1?/? (27.6 ± 3.3%) neurons. In the presence of the EP1 receptor antagonist SC-51089, the hemin-induced release of LDH decreased. To further investigate potential mechanisms of action, we measured changes in the intracellular calcium level [Ca2+]i following treatment with 17-phenyl trinor PGE2 (17-pt-PGE2) a selective EP1 agonist. In the WT neurons, 17-pt-PGE2 dose-dependently increased [Ca2+]i. However, in EP1?/? neurons, [Ca2+]i was significantly attenuated. We also revealed that hemin dose-dependently increased [Ca2+]i in WT neurons, with a significant decrease in EP1?/? neurons. Both 17-pt-PGE2 and hemin-induced [Ca2+]i were abolished by N-methyl-D-aspartic (NMDA) acid receptor and ryanodine receptor blockers. These results suggest that blockade of the EP1 receptor may be protective against hemin neurotoxicity in vitro. We speculate that the mechanism of hemin neuronal death involves [Ca2+]i mediated by NMDA acid receptor-mediated extracellular Ca2+ influx and EP1 receptor-mediated intracellular release from ryanodine receptor-operated Ca2+ stores. Therefore, blockade of the EP1 receptor could be used to minimize neuronal damage following exposure to supraphysiological levels of hemin.
Electron-Irradiation and Photo-Excitation Darkening and Bleaching of Yb Doped Silica Fibers: Comparison  [PDF]
Alexander V. Kir’yanov
Optics and Photonics Journal (OPJ) , 2011, DOI: 10.4236/opj.2011.14026
Abstract: We report a comparative experimental study of the attenuation spectra transformations for a series of Yb doped alumino-germano silicate fibers with different contents of Yb3+ dopants, which arise as the result of irradiation either by a beam of high-energy electrons or by resonant (into the 977-nm absorption peak of YbYb3+ ions) optical pumping. The experimental data obtained reveal that in the two circumstances, substantial and complex but different in appearance changes occur within the resonant absorption band of YbYb3+ ions and in the off-resonance background loss of the fibers. Possible mechanisms responsible for these spectral changes are discussed.
Post-Procedure Mortality after Cardiovascular Treatment Procedures in Patients with Pneumoconiosis  [PDF]
Alexander V. Sergeev
Occupational Diseases and Environmental Medicine (ODEM) , 2015, DOI: 10.4236/odem.2015.31002
Pneumoconiosis (PNC) is a major occupational disease that develops as a result of occupational exposure to dust via inhalation. In addition to its harmful effects on the respiratory system, PNC can increase vulnerability to coronary heart disease (CHD)—the leading cause of death in the United States and in the world. Currently, two types of cardiovascular intervention procedures for CHD treatment are percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG). The objective of this study was to investigate comparative effectiveness of the two major cardiovascular intervention procedures—PCI and CABG—in PNC patients with CHD. Data from 1094 hospitalizations of adult patients with PNC and CHD (CHD-PNC patients) and 534,120 hospi-talizations of CHD patients without PNC (CHD-nonPNC) were investigated. Adjusted odds ratios for in-hospital death in relation to the type of procedure, adjusted for patient socio-demographic and clinical characteristics and hospital characteristics, were calculated using multivariable logistic regression. Men constituted 97.8% of CHD-PNC patients and 68.6% of CHD-nonPNC patients. Within the CHD-PNC group, crude (unadjusted) in-hospital mortality after CABG and PCI did not differ significantly (1.35% vs. 2.00%, p = 0.425) and remained insignificant in the multivariable analysis, adjusted for patient and hospital characteristics (adjusted OR = 0.714, 95% CI 0.220 - 2.323, p = 0.576). But in the CHD-nonPNC group, in-hospital mortality after CABG was significantly higher than after PCI both in crude analysis (2.83% vs. 1.28%, p < 0.001) and adjusted analysis (adjusted OR = 1.637, 95% CI 1.541 - 1.738, p < 0.001). The study results indicate that CABG is as safe as PCI in male CHD-PNC patients, in terms of in-hospital mortality. Further studies investigating comparative effectiveness of cardiovascular procedures in PNC patients using more detailed data are warranted.
Application Concept of Zero Method Measurement in Microwave Radiometers  [PDF]
Alexander V. Filatov
Modern Instrumentation (MI) , 2015, DOI: 10.4236/mi.2015.43003
Abstract: This article examined in detail microwave radiometer functioning algorithm with synchronously using of the two types of pulse modulation: amplitude pulse modulation and pulse-width modulation. This allows a zero-radiometer measurement method to realize when the fluctuation effect of the receiver gain and the influence of its own noise changes are minimized. A zero balance automatically maintains in radiometer. The antenna signal is indirectly determined through the signal duration that controls the pulse-width modulation. An analytical expression of the fluctuation sensitivity was obtained in a general form. From its analysis gain in sensitivity, conditions were defined by the optimizing of the radiometer input knot’s construction. Three modifications of the radiometer input knot were researched. Fluctuation sensitivity at different measurement range was determined for modification of the radiometer input knot.
Gravitational Telescope  [PDF]
Alexander V. Lukanenkov
Journal of High Energy Physics, Gravitation and Cosmology (JHEPGC) , 2016, DOI: 10.4236/jhepgc.2016.22019
Abstract: It’s proposed to use a global seismic antenna (GSA) as a gravitational telescope, arbitrary “quiet” seismic stations are its elements, and aperture of GSA must be of the order 10,000 km. The relative displacements of various points of the Earth are detected by GSA, these displacements are described as quasi-harmonic elliptical signals generated by gravitational waves, their amplitude ≈ 2.5 * 0?15 m. It is found that these waves cause deformation (strain) of the order h ≈ 10?21. Pulsars are a natural source of periodic waves. The fact of confident registration of gravitational wave is confirmed by detection of quasi-harmonic signals in the frequency band near 6.023 Hz for 90 hours (confidence probability of detection is close to 1). It is found that a small part of the rotation energy of associated pulsar (ε ≈ 10?5) is expended on the radiation corresponding to the gravitational wave.
Experimental Confirmation of the Doubts about Authenticity of Event GW150914  [PDF]
Alexander V. Lukanenkov
Journal of Applied Mathematics and Physics (JAMP) , 2017, DOI: 10.4236/jamp.2017.52046
Abstract: It was produced processing of the LIGO 14.09.2015 registration data. It was established that the chirp signals (signals of merger of black holes) are absent in the data. This is proved by using a coherent filtering and also two-stage causal filtering. Soliton-like signals such as wavelet “Mexican hat” are found by filtering based on the Butterworth filter. These signals are different in polarity, and their spectra are quite different. Doubts about the authenticity of the detection of chirp signals, which announced on February 11, 2016, are justified by the results the conducted analysis.
The Chemical Mechanism of the Formation of Fluorite-Barite-Siderite Carbonatite in Karasug Fe-F-Ba-Sr-REE Deposit  [PDF]
Alexander V. Bolonin
Open Journal of Geology (OJG) , 2018, DOI: 10.4236/ojg.2018.84023
Abstract: Intrusive fluorite-barite-siderite carbonatite of Karasug deposit (Tuva) crystallized from ionic salt melt is dominated by iron chloride with the participation of alkali metal salts. Melt composition and main reaction of mineral formation: NaFeCl3 + 4KF + 2Na2Ca(CO3)2 + Na2Ba(CO3)2 + Na2SO4 = 6FeCO3 + 2CaF2 + BaSO4 + 14NaCl + 4KCl. The highest temperature (550°C - 650°C) brine-melt inclusions in minerals are pseudo-primary. Their predominant Na-K-chloride composition does not correspond to the primary melt, but is close to the residual brine-melt.
Epitaxial Ge Growth on Si(111) Covered with Ultrathin SiO2 Films  [PDF]
Alexander A. Shklyaev, Konstantin N. Romanyuk, Alexander V. Latyshev
Journal of Surface Engineered Materials and Advanced Technology (JSEMAT) , 2013, DOI: 10.4236/jsemat.2013.33027

The epitaxial growth of Ge on Si(111) covered with the 0.3 nm thick SiO2 film is studied by scanning tunneling microscopy. Nanoareas of bare Si in the SiO2 film are prepared by Ge deposition at a temperature in the range of 570℃-650℃ due to the formation of volatile SiO and GeO molecules. The surface morphology of Ge layers grown further at 360℃-500℃ is composed of facets and large flat areas with the Ge(111)-c(2 × 8) reconstruction which is typical of unstrained Ge. Orientations of the facets, which depend on the growth temperature, are identified. The growth at 250℃-300℃ produces continuous epitaxial Ge layers on Si(111). A comparison of the surface morphology of Ge layers grown on bare and SiO2-film covered Si(111) surfaces shows a significantly lower Ge-Si intermixing in the latter case due to a reduction in the lattice strain. The found approach to reduce the strain suggests the opportunity of the thin continuous epitaxial Ge layer formation on Si(111).

The capabilities of the calculated approach for the astroclimatic assessment in radioastronomy  [PDF]
Nikolay V. Ruzhentsev, Alexander S. Mihailov
Natural Science (NS) , 2010, DOI: 10.4236/ns.2010.25052
Abstract: The work is dedicated to calculation of daily variability of monthly averaged full vertical at-mospheric absorption for six well-known moun- tain locations of sub-millimeter wave band ra-diotelescopes obtained with usage of chosen by authors models combination. Test locations we- re defined as follows: Chajnantor plateau in the Atacama mountain desert (Chile), Hanle (India), South Pole (Antarctic), Mauna Kea (Hawaii, USA), Sierra Negra (Puebla, Mexico) and El Leoncito (Argentine). The data of these calculations were compared with the data of long term radiometric observations of other authors. Se- arching for new alternative places to complement existing sub-millimeter telescopes locations was attempted too.
Computer-assisted anti-AIDS drug development: cyclophilin B against the HIV-1 subtype A V3 loop  [PDF]
Alexander M. Andrianov, Ivan V. Anishchenko
Health (Health) , 2010, DOI: 10.4236/health.2010.27100
Abstract: Aim: The objects of this study originated from the experimental observations, whereby the HIV -1 gp120 V3 loop is a high-affinity ligand for immunophilins, and consisted in generating the structural complex of cyclophilin (Cyc) B belonging to immunophilins family with the virus subtype A V3 loop (SA-V3 loop) as well as in specifying the Cyc B segment forming the binding site for V3 synthetic copy of which, on the assumption of keeping the 3D peptide structure in the free state, may present a forwardlooking basic structure for anti-AIDS drug development. Methods: To reach the objects of view, molecular docking of the HIV-1 SA-V3 loop structure determined previously with the X-ray conformation of Cyc B was put into practice by Hex 4.5 program (http://www.loria.fr/~ritchied/ hex/) and the immunophilin stretch responsible for binding to V3 (Cyc B peptide) was identified followed by examination of its 3D structure and dynamic behavior in the unbound status. To design the Cyc B peptide, the X-ray conformation for the identical site of the native protein was involved in the calculations as a starting model to find its best energy structural variant. The search for this most preferable structure was carried out by consecutive use of the molecular mechanics and simulated annealing methods. The molecular dynamics computations were implemented for the Cyc B peptide by the GROMACS computer package (http:// www.gromacs.org/). Results: The overmolecular structure of Cyc B with V3 was built by computer modeling tools and the immunophilinderived peptide able to mask effectively the structurally invariant V3 segments embracing the functionally crucial amino acids of the HIV-1 gp120 envelope protein was constructed and analyzed. Conclusions: Starting from the joint analysis of the results derived with those of the literature, the generated peptide was suggested to offer a promising basic structure for making a reality of the protein engineering projects aimed at developing the anti-AIDS drugs able to stop the HIV’s spread.
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