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Search Results: 1 - 10 of 130458 matches for " Sreevidya .V "
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Spectrophotometric determination of nevirapine using tetrathiocyanatocobalt(II) ion as a reagent
Sreevidya, T. V;Narayana, B;
Eclética Química , 2010, DOI: 10.1590/S0100-46702010000300008
Abstract: a simple and rapid spectrophotometric method for the determination of nevirapine is described. the method is based on the reaction of nevirapine with tetrathiocyanatocobalt(ii) ion in buffer of ph 4 to form the corresponding complex. beer's law is obeyed in the range of 0.2 - 2.0 μg ml-1 for nevirapine. the optical parameters such as molar absorptivity, sandell's sensitivity, detection limit and quantitation limit were found to be 1.16× 104 lmol-1cm-1, 2.09 x 10-3 μg cm-2, 0.073 μg ml-1 and 0.222 μg ml-1 respectively. the optimum reaction conditions and other analytical parameters were evaluated. the statistical evaluation of the method was examined by determining intra-day and inter-day precision. the proposed method has been successfully applied for the determination of nevirapine in pharmaceutical formulations.
(E)-1-(1,3-Benzodioxol-5-yl)-3-(3-bromophenyl)prop-2-en-1-one
Hongqi Li,T. V. Sreevidya,B. Narayana,B. K. Sarojini
Acta Crystallographica Section E , 2008, DOI: 10.1107/s1600536808037446
Abstract: In the title compound, C16H11BrO3, the molecules adopt an E configuration with respect to the C=C double bond of the propenone unit. The 13 non-H atoms of the benzodioxole and propenone units are approximately coplanar (r.m.s. deviation = 0.027 ) and the bromobenzene ring plane forms a dihedral angle of 10.8 (1)° to this plane. The structure is layered, with the molecules forming a herring-bone arrangement within each layer.
ACID RESISTANCE OF FLYASH BASED GEOPOLYMER MORTAR UNDER AMBIENT CURING AND HEAT CURING
V.Sreevidya,R. Anuradha,D.Dinakar,Dr.R.Venkatasubramani
International Journal of Engineering Science and Technology , 2012,
Abstract: An Experimental study was conducted to assess the Acid resistance of flyash based geopolymer mortar specimens of size 50x50x50mm with a ratio of flyash to sand as 1:3.The ratio between solution(Sodiumhydroxide and Sodium silicate solution) to flyash were 0.376,0.386,0.396 and 0.416. After casting the specimens were subjected to both ambient curing and heat curing. In heat curing the specimens were kept continuously at 60oC for 24 hrs. Durability of specimens was assessed by immersing them in 5% of sulfuric acid and 5%hydrochloric acid for a period of 14 weeks. Evaluation of its resistance in terms of change in weight, compressive strength and visual appearance at regular intervals was carried out. After exposure in the acid solutions for 14 weeks, the samples showed very low weight loss. Results obtained from the present study indicate that Geopolymers are highly resistance to sulfuric acid and hydrochloric acid.
Comparative Study on Cold Form Purlins for Distortional Buckling Behaviour
Govindasamy.P,Sreevidya .V,Dr.L.S.Jayagopal
International Journal of Engineering Sciences & Research Technology , 2013,
Abstract: This paper presents the comparative study on cold form purlin sections under distortional buckling behaviour. The “C” purlins are now-a-days widely used in all industrial buildings. It is made up of steel sheets, thickness ranges from 0.8mm to 5mm and formed by cold process. It is extensively used for the advantage of lightweight, low cost and easy manufacturing. In the present study, an analysis has been made to understand the behaviour of cold formed “C” purlins for gravity and wind load conditions. In actual practice compression flanges and tension flanges are laterally restrained by roof sheeting in gravity and wind loading respectively. For this study, actual full scale model test have been conducted in laboratory, for above said boundary conditions. Uniformly distributed load was applied and vertical and lateral deflection was measured. In addition, a numerical study using finite element analysis was done for the above said case. For the analysis ANSYS 10.0 software was used. Finally a comparative study is made between theoretical and experimental results.
Antibacterial and antioxidant activity of methanol extract of Evolvulus nummularius
Pavithra P,Sreevidya N,Verma Rama
Indian Journal of Pharmacology , 2009,
Abstract: Objective : To evaluate the antibacterial and antioxidant activity of methanol extract of Evolvulus nummularius (L) L. Materials and Methods : Disc diffusion and broth serial dilution tests were used to determine the antibacterial activity of the methanol extract against two Gram-positive bacterial strains (Bacillus subtilus NCIM 2718, Staphylococcus aureus ATCC 25923) and three Gram-negative bacterial strains (Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae ATCC 70063 and Escherichia coli ATCC 25922). The methanol extract was subjected to preliminary phytochemical analysis. Free radical scavenging activity of the methanol extract at different concentrations was determined with 2, 2-diphenyl-1picrylhydrazyl (DPPH). Results : The susceptible organisms to the methanol extract were Escherichia coli (MIC=12.50 mg/ml) and Bacillus subtilus (MIC=3.125 mg/ml) and the most resistant strains were Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa. The methanol extracts exhibited radical scavenging activity with IC50 of 350 μg/ml. Conclusion : The results from the study show that methanol extract of E.nummularius has antibacterial activity. The antioxidant activity may be attributed to the presence of tannins, flavonoids and triterpenoids in the methanol extract. The antibacterial and antioxidant activity exhibited by the methanol extract can be corroborated to the usage of this plant in Indian folk medicine.
Mitochondrial and Plasma Membrane Citrate Transporters: Discovery of Selective Inhibitors and Application to Structure/Function Analysis
Jiakang Sun,Sreevidya Aluvila,Rusudan Kotaria,June A. Mayor
Molecular and Cellular Pharmacology , 2010,
Abstract: Cytoplasmic citrate is the prime carbon source for fatty acid, triacylglycerol, and cholesterol biosyntheses, and also regulates glucose metabolism via its allosteric inhibition of phosphofructokinase. It originates either via the efflux of citrate from the mitochondrial matrix on the inner membrane citrate transport protein (CTP) or via the influx of extracellular citrate on the plasma membrane citrate transporter (PMCT). Despite their common substrate, the two transport proteins share little sequence similarity and they transport citrate via fundamentally different mechanisms. We tested the ability of a set of previously identified CTP inhibitors, to inhibit the PMCT. We found that of the top 10 CTP inhibitors only one substantially inhibited the PMCT. Conversely, we identified two other inhibitors that inhibited the PMCT but had little effect on the CTP. All three identified PMCT inhibitors displayed a noncompetitive mechanism. Furthermore, models to explain inhibitor interactions with the CTP are proposed. As part of the present studies a PMCT homology model has been developed based on the crystal structure of the leucine transporter, and a possible citrate binding site has been identified and its composition compared with the two known citrate binding sites present within the CTP. The ability to selectively inhibit the PMCT may prove key to the pharmacologic amelioration of metabolic disorders resulting from the synthesis of excess lipid, cholesterol, and glucose, including human obesity, hyperlipidemia, hyper-cholesterolemia, and Type 2 diabetes.
Antineoplastic Effects of α-Santalol on Estrogen Receptor-Positive and Estrogen Receptor-Negative Breast Cancer Cells through Cell Cycle Arrest at G2/M Phase and Induction of Apoptosis
Sreevidya Santha, Ajay Bommareddy, Brittny Rule, Ruth Guillermo, Radhey S. Kaushik, Alan Young, Chandradhar Dwivedi
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0056982
Abstract: Anticancer efficacy and the mechanism of action of α-santalol, a terpenoid isolated from sandalwood oil, were investigated in human breast cancer cells by using p53 wild-type MCF-7 cells as a model for estrogen receptor(ER)-positive and p53 mutated MDA-MB-231 cells as a model for ER-negative breast cancer. α-Santalol inhibited cell viability and proliferation in a concentration and time-dependent manner in both cells regardless of their ER and/or p53 status. However, α-santalol produced relatively less toxic effect on normal breast epithelial cell line, MCF-10A. It induced G2/M cell cycle arrest and apoptosis in both MCF-7 and MDA-MB-231 cells. Cell cycle arrest induced by α-santalol was associated with changes in the protein levels of BRCA1, Chk1, G2/M regulatory cyclins, Cyclin dependent kinases (CDKs), Cell division cycle 25B (Cdc25B), Cdc25C and Ser-216 phosphorylation of Cdc25C. An up-regulated expression of CDK inhibitor p21 along with suppressed expression of mutated p53 was observed in MDA-MB-231 cells treated with α-santalol. On the contrary, α-santalol did not increase the expression of wild-type p53 and p21 in MCF-7 cells. In addition, α-santalol induced extrinsic and intrinsic pathways of apoptosis in both cells with activation of caspase-8 and caspase-9. It led to the activation of the executioner caspase-6 and caspase-7 in α-santalol-treated MCF-7 cells and caspase-3 and caspase-6 in MDA-MB-231 cells along with strong cleavage of poly(ADP-ribose) polymerase (PARP) in both cells. Taken together, this study for the first time identified strong anti-neoplastic effects of α-santalol against both ER-positive and ER-negative breast cancer cells.
Comparing Imputation Procedures for Affymetrix Gene Expression Datasets Using MAQC Datasets
Sreevidya Sadananda Sadasiva Rao,Lori A. Shepherd,Andrew E. Bruno,Song Liu,Jeffrey C. Miecznikowski
Advances in Bioinformatics , 2013, DOI: 10.1155/2013/790567
Abstract: Introduction. The microarray datasets from the MicroArray Quality Control (MAQC) project have enabled the assessment of the precision, comparability of microarrays, and other various microarray analysis methods. However, to date no studies that we are aware of have reported the performance of missing value imputation schemes on the MAQC datasets. In this study, we use the MAQC Affymetrix datasets to evaluate several imputation procedures in Affymetrix microarrays. Results. We evaluated several cutting edge imputation procedures and compared them using different error measures. We randomly deleted 5% and 10% of the data and imputed the missing values using imputation tests. We performed 1000 simulations and averaged the results. The results for both 5% and 10% deletion are similar. Among the imputation methods, we observe the local least squares method with is most accurate under the error measures considered. The k-nearest neighbor method with has the highest error rate among imputation methods and error measures. Conclusions. We conclude for imputing missing values in Affymetrix microarray datasets, using the MAS 5.0 preprocessing scheme, the local least squares method with has the best overall performance and k-nearest neighbor method with has the worst overall performance. These results hold true for both 5% and 10% missing values. 1. Introduction In microarray experiments, randomly missing values may occur due to scratches on the chip, spotting errors, dust, or hybridization errors. Other nonrandom missing values may be biological in nature, for example, probes with low intensity values or intensity values that may exceed a readable threshold. These missing values will create incomplete gene expression matrices where the rows refer to genes and the columns refer to samples. These incomplete expression matrices will make it difficult for researchers to perform downstream analyses such as differential expression inference, clustering or dimension reduction methods (e.g., principal components analysis), or multidimensional scaling. Hence, it is critical to understand the nature of the missing values and to choose an accurate method to impute the missing values. There have been several methods put forth to impute missing data in microarray experiments. In one of the first papers related to microarrays, Troyanskaya et al. [1] examine several methods of imputing missing data and ultimately suggest a -nearest neighbors approach. Researchers also explored applying previously developed schemes for microarrays such as the nonlinear iterative partial least
Induction of B-cell lymphoma by UVB Radiation in p53 Haploinsufficient Mice
Nahum Puebla-Osorio, Yasuko Miyahara, Sreevidya Coimbatore, Alberto Y Limón-Flores, Nasser Kazimi, Stephen E Ullrich, Chengming Zhu
BMC Cancer , 2011, DOI: 10.1186/1471-2407-11-36
Abstract: UVB-irradiated p53+/- mice developed enlargement of the spleen. Isolated spleen cells were transplanted into Rag deficient hosts. The UV-induced tumor cells were analyzed by flow cytometry. The tumor cells were tagged with GFP to study their metastatic potential. SKY and karyotypic analysis were carried out for the detection of chromosomal abnormalities. Functional assays included in vitro class switch recombination assay, immunoglobulin rearrangement assay, as well as cytokine profiling.UVB-exposed mice showed enlargement of the spleen and lymph nodes. Cells transplanted into Rag deficient mice developed aggressive tumors that infiltrated the lymph nodes, the spleen and the bone marrow. The tumor cells did not grow in immune competent syngeneic C57Bl/6 mice yet showed a modest growth in UV-irradiated B6 mice. Phenotypic analysis of these tumor cells revealed these cells are positive for B cell markers CD19+, CD5+, B220+, IgM+ and negative for T cell, NK or dendritic cell markers. The UV-induced tumor cells underwent robust in vitro immunoglobulin class switch recombination in response to lipopolysaccharide. Cytogenetic analysis revealed a t(14;19) translocation and trisomy of chromosome 6. These tumor cells secret IL-10, which can promote tumor growth and cause systemic immunosuppression.UV-irradiated p53+/- mice developed lymphoid tumors that corresponded to a mature B cell lymphoma. Our results suggest that an indirect mechanism is involved in the development of internal tumors after chronic exposure to UV light. The induction of B cell lymphoma in UV-irradiated p53 heterozygous mice may provide a useful model for lymphoma development in humans.The incidence of non-Hodgkin's lymphoma has increased over recent years, an increase that cannot be totally explained by improvements in diagnosis or reporting. The exact etiology of lymphoma remains unknown but viral infection, chronic antigen stimulation, and/or immunosuppression, either primary or acquired immunodeficie
Nonsmooth Optimization Algorithms in Some Problems of Fracture Dynamics  [PDF]
V. V. Zozulya
Intelligent Information Management (IIM) , 2010, DOI: 10.4236/iim.2010.211073
Abstract: Mathematical statement of elastodynamic contact problem for cracked body with considering unilateral restrictions and friction of the crack faces is done in classical and weak forms. Different variational formulations of unilateral contact problems with friction based on boundary variational principle are considered. Nonsmooth optimization algorithms of Udzawa’s type for solution of unilateral contact problem with friction have been developed. Convergence of the proposed algorithms has been studied numerically.
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