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排序方式: 共有401条查询结果,搜索用时 15 毫秒
141.
Pradip Kumar Sunil Dutt Sharma Rakesh Mohan Chandola Devesh Ramdhar Mishra Bhushan Dhabekar Narender Singh Rawat Sonal Kadam Sadhana Agrawal 《Luminescence》2019,34(4):444-449
Dental orthopantogram (OPG)/cone beam computed tomography (CBCT) scanners are gaining popularity due to their 3D imaging with multiplanar view that provides clinical benefits over conventional dental radiography systems. Dental OPG/CBCT provides optimal visualization of adjacent overlaying anatomical structures that will be superpositioned in any single projection. The characteristics of indigenously developed optically stimulated luminescence dosimeters, namely, aluminium oxide doped with carbon (Al2O3:C), lithium magnesium phosphate doped with terbium and boron (LiMgPO4:Tb,B) and lithium calcium aluminium fluoride doped with europium and yttrium (LiCaAlF6:Eu,Y) were evaluated for their use in dental dosimetry. The dose?response of these dosimeters was studied at X‐ray energies 60 kV, 70 kV and 81 kV. Radiation doses were also measured using Gafchromic film for comparison. Radiation dose was measured at eight different locations of a polymethyl methacrylate (PMMA) head phantom including eyes. The optically stimulated luminescence (OSL) sensitivity of LiMgPO4:Tb,B is about 1.5 times and LiCaAlF6:Eu, is about 20 times higher than the sensitivity of Al2O3:C. It was found that measured radiation doses by the three optically stimulated luminescence dosimeters (OSLDs) and Gafchromic film in the occipital region (back side) of a PMMA phantom, were consistent but variations in dose at other locations were significantly higher. The three OSLDs used in this study were found to be suitable for radiation dose measurement in dental units. 相似文献
142.
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144.
Two selective novel triterpene glycosides from sea cucumber,Telenata Ananas: inhibitors of chemokine receptor-5 总被引:5,自引:0,他引:5
Hegde VR Chan TM Pu H Gullo VP Patel MG Das P Wagner N Parameswaran PS Naik CG 《Bioorganic & medicinal chemistry letters》2002,12(21):3203-3205
The aqueous methanolic extract of a sea cucumber was found to contain two triterpene glycosides 1 and 2. The structures of 1 and 2 were established based on high-resolution NMR studies. Compounds 1 and 2 exhibited inhibitory activity (K(i)) of 30 and 5microM, respectively, in a chemokine receptor subtype 5 (CCR5) assay. Both compounds did not show any significant inhibition in a CXCR2 assay at 50microM, suggesting their selectivity for the CCR5 receptor. 相似文献
145.
Pradip?K. Tarafdar Hirak Chakraborty S.?Moses Dennison Barry?R. Lentz 《Biophysical journal》2012,103(9):1880-1889
PEG-mediated fusion of SUVs composed of dioleoylphosphatidylcholine, dioleoylphosphatidylethanolamine, sphingomyelin, cholesterol, and dioleoylphosphatidylserine was examined to investigate the effects of PS on the fusion mechanism. Lipid mixing, content mixing, and content leakage measurements were carried out with vesicles containing from 0 to 8 mol % PS and similar amounts of phosphatidylglycerol. Fitting these time courses globally to a 3-state (aggregate, intermediate, pore) sequential model established rate constants for each step and probabilities of lipid mixing, content mixing, and leakage in each state. Charged lipids inhibited both the rates of intermediate and pore formation as well as the extents of lipid and contents mixing, although electrostatics were not solely responsible for inhibition. Ca2+ counteracted this inhibition and increased the extent of fusion in the presence of PS to well beyond that seen in the absence of charged lipids. The effects of both PS and Ca2+ could be interpreted in terms of a previous proposal for the nature of lipid fluctuations that account for transition states for the two steps of the fusion process examined. The results suggest a more significant role for Ca2+-lipid interactions than is acknowledged in current thinking about cell membrane fusion.Abbreviations used: SUVs, small unilamellar vesicles; DOPC, 1,2-dioleoyl-3-sn-phosphatidylcholine; DOPE, 1,2-dioleoyl-3-sn-phosphatidylethanolamine; SM, sphingomyelin (bovine brain); CH, Cholesterol; DOPS, 1,2-dioleoyl-3-sn-phosphatidylserine; PS, phosphatidylserine; DOPG, 1,2-dioleoyl-3-sn-phosphatidylglycerol; PG, phosphatidylglycerol; TES, N- tris(hydroxymethyl)methyl}2-2-aminoethane sulfonic acid; PEG, poly(ethylene glycol); CM, contents mixing; LM, lipid mixing 相似文献
146.
Hegde VR Pu H Patel M Das PR Butkiewicz N Arreaza G Gullo VP Chan TM 《Bioorganic & medicinal chemistry letters》2003,13(17):2925-2928
The 70% aq methanolic extract of the Peruvian plant Stylogne cauliflora was found to contain two novel oligophenolic compounds SCH 644343 (1) and SCH 644342 (2), which were identified as inhibitors of HCV NS3 protease. The structure of 1 and 2 was established based on high-resolution NMR studies. Compound 1 inhibited HCV NS3 protease with an IC(50) of 0.3 microM, while compound 2 showed an IC(50) of 0.8 microM. 相似文献
147.
Nandan CK Patra P Bhanja SK Adhikari B Sarkar R Mandal S Islam SS 《Carbohydrate research》2008,343(18):3120-3122
A water-soluble polysaccharide, isolated from the hot aqueous extract of an edible mushroom, Agaricus bitorquis, was found to consist of d-glucose only. On the basis of total hydrolysis, methylation analysis, and NMR studies (1H, 13C, TOCSY, DQF-COSY, NOESY, ROESY, HMQC, and HMBC), the structure of the repeating unit was established as→6)-β-d-Glcp-(1→ 相似文献
148.
Himmatsinh U. Solanki Pradip C. Mankodi Rashmin M. Dwivedi Shailesh R. Nayak 《Hydrobiologia》2008,612(1):269-279
Ecological associations are the inter-relationship between the species and their environment. Oceanographic processes like
upwelling events and formation of eddies, rings, and fronts have been monitored using National Oceanic and Atmospheric Administration
Advanced Very High Resolution (NOAA AVHRR) and Indian Remote Sensing Satellite-P4-Ocean Colour Monitor (IRS-OCM) data. Sea
Surface Temperature (SST) and chlorophyll concentration (CC) images were derived from AVHRR and OCM, respectively. Upwelling
event was monitored using AVHRR-SST by detecting the differences in surface water temperature. The formation of eddies, rings,
cyclonic eddies, and anti-cyclonic eddies and their biological responses were studied using CC. Eddies and rings were found
with high phytoplankton production in the form of bloom, which provide grazing ground for fishes. The anti-cyclonic eddies
were found with very low CC, indicating the biological deserts in the ocean. The impacts of these processes on fish catch
were studied using fishing operations data procured from Fishery Survey of India. In this paper, the occurrence of different
oceanographic processes, their persistence, and relevance with catch statistics of fishery resources in the study area are
discussed. The study explains the potentials of satellite remote sensing to establish the habitat linkage between oceanographic
processes and fishery resources.
Guest editor: V. D. Valavanis
Essential Fish Habitat Mapping in the Mediterranean 相似文献
149.
Thakur M Chaba R Mondal AK Chakraborti PK 《The Journal of biological chemistry》2008,283(12):8023-8033
Eukaryotic type Ser/Thr protein kinases have recently been shown to regulate a variety of cellular functions in bacteria. PknA, a transmembrane Ser/Thr protein kinase from Mycobacterium tuberculosis, when constitutively expressed in Escherichia coli resulted in cell elongation and therefore has been thought to be regulating morphological changes associated with cell division. Bioinformatic analysis revealed that PknA has N-terminal catalytic, juxtamembrane, transmembrane, and C-terminal extracellular domains, like known eukaryotic type Ser/Thr protein kinases from other bacteria. To identify the minimum region capable of exhibiting phosphorylation activity of PknA, we created several deletion mutants. Surprisingly, we found that the catalytic domain itself was not sufficient for exhibiting phosphorylation ability of PknA. However, the juxtamembrane region together with the kinase domain was necessary for the enzymatic activity and thus constitutes the catalytic core of PknA. Utilizing this core, we deduce that the autophosphorylation of PknA is an intermolecular event. Interestingly, the core itself was unable to restore the cell elongation phenotype as manifested by the full-length protein in E. coli; however, its co-expression along with the C-terminal region of PknA can associate them in trans to reconstitute a functional protein in vivo. Therefore, these findings argue that the transmembrane and extracellular domains of PknA, although dispensable for phosphorylation activities, are crucial in responding to signals. Thus, our results for the first time establish the significance of different domains in a bacterial eukaryotic type Ser/Thr kinase for reconstitution of its functionality. 相似文献
150.
Saxena R Kanudia P Datt M Dar HH Karthikeyan S Singh B Chakraborti PK 《The Journal of biological chemistry》2008,283(35):23754-23764
Genes encoding the peptide deformylase enzyme (def) are present in all eubacteria and are involved in the deformylation of the N-formyl group of newly synthesized polypeptides during protein synthesis. We compared the amino acid sequences of this enzyme in different mycobacterial species and found that they are highly conserved (76% homology with 62% identity); however, when this comparison was extended to other eubacterial homologs, it emerged that the mycobacterial proteins have an insertion region containing three consecutive arginine residues (residues 77-79 in Mycobacterium tuberculosis peptide deformylase (mPDF)). Here, we demonstrate that these three arginines are important for the activity of mPDF. Circular dichroism studies of wild-type mPDF and of mPDF containing individual conservative substitutions (R77K, R78K, or R79K) or combined substitutions incorporated into a triple mutant (R77K/R78K/R79K) indicate that such mutations cause mPDF to undergo structural alterations. Molecular modeling of mPDF suggests that the three arginines are distal to the active site. Molecular dynamics simulations of wild-type and mutant mPDF structures indicate that the arginines may be involved in the stabilization of substrate binding pocket residues for their proper interaction with peptide(s). Treatment with 5'-phosphothiorate-modified antisense oligodeoxyribonucleotides directed against different regions of def from M. tuberculosis inhibits growth of Mycobacterium smegmatis in culture. Taken together, these results hold out the possibility of future design of novel mycobacteria-specific PDF inhibitors. 相似文献