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Tirupati, India

Seshadri M.,University of Campinas | Ferencz Junior J.A.P.,University of Campinas | Ratnakaram Y.C.,Sri Venateswara University | Barbosa L.C.,University of Campinas
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

Several papers were reported on spectroscopic properties of rare earth doped different host glasses. A complete knowledge of fluorescence properties of rare earth ions in laser materials is necessary to achieve efficient, compact and cheap sources of laser radiation for NIR and mid-IR region. Tellurite glasses are potentially useful for generation of NIR and mid-IR laser radiation due to its special features such as lowest phonon energy (750 cm-1) among oxide glasses, reasonably wide transmission region (0.35 - 5μm), good glass stability, good rare earth ion solubility, high linear and non-linear refractive index. In the present work, authors prepared Ho3+ and Tm3+ singly doped and Ho3+/Tm3+ co-doped tellurite glasses using conventional melt-quenching method. Spectroscopic measurements and analysis of energy transfer process in Ho3+, Tm 3+ and Ho3+ /Tm3+ co-doped glasses pumped with 785nm and 451 nm excitation wavelengths have been performed. There are some spectroscopic properties which are important in understanding and modeling of rare earth doped laser materials. Using Judd-Ofelt theory, radiative transition rates (Arad), radiative lifetimes (τR) and branching ratios (β) were estimated for certain excited states of Ho3+ and Tm3+ doped tellurite glasses. The emission cross-sections and gain coefficients have been determined from the absorption spectra of Ho3+ and Tm3+ ions in tellurite glasses. The energy transfer process such as ion cross-relaxation, Tm3+-Ho3+ energy transfer and energy transfer upconversion were studied and identified to specific candidate for laser operation. © 2014 SPIE. Source


Murthy J.,Sri Ramachandra University | Gurramkonda V.B.,Sri Ramachandra University | Lakkakula S.,Sri Venateswara University | Pathapati R.M.,Narayana Medical College | And 2 more authors.
Turkish Journal of Biochemistry | Year: 2013

Objective: Nonsyndromic cleft lip with or without cleft palate (NSCLP) is a common birth defect with substantial clinical and social impact, and whose causes include both genetic and environmental factors. Folate and homocysteine metabolism have been indicated to play a role in the etiology of NSCLP. The aim of this study was to determine the prevalence of NOS3 27-bp VNTR and to evaluate whether this polymorphism contributed to the risk of NSCLP. Material and methods: We studied the 27 base pair tandem repeat polymorphism in intron 4 of the endothelial nitric oxide synthase (NOS3) gene in 230 unrelated individuals belong to 7 Indian populations along with 141 NSCLP cases and 142 unrelated controls. The genotyping was performed by polymerase chain reaction and electrophoresis. The data were statistically analysed using the χ2-test. Results: The NOS3 27-bp VNTR 4a allele is present in six of the seven populations analysed and allele frequencies range from 6.8% in Sugali to 23.5% in Madiga populations. NOS3 showed protective association with predisposition towards NSCLP for the heterozygous (4b/a) genotypes (4b/b vs. 4b/a: OR =0.58, 95% CI =0.34 to 0.99, p=0.044). Conclusions: The current study suggests significant differences in the frequency of the NOS3 VNTR allele across the populations. There is protective association between NOS3 27-bp VNTR polymorphism and NSCLP in the Indian population. © TurkJBiochem.com. Source


Lakkakula S.,Sri Venateswara University | Maram R.,Sri Venateswara University | Munirajan A.K.,University of Madras | Pathapati R.M.,Narayana Medical College | And 2 more authors.
Journal of Cell and Molecular Biology | Year: 2013

CYP1A1 is a phase I detoxifying enzyme which catalyzes the conversion of environmental procarcinogens to reactive, carcinogenic intermediates. Certain polymorphic variants of CYP1A1 gene are known to cause enhanced enzyme activity and play a major role in the pathogenesis of several cancers. The present study was conducted to investigate the allele frequency variations in Indian populations. Two hundred and twelve subjects belong to six populations were screened for tagSNPs of CYP1A1 (IVS1-728G>A and Ile462Val) using TaqMan allelic discrimination. Both IVS1-728G>A and Ile462Val are polymorphic and followed the Hardy-Weinberg equilibrium in all populations. The Ile462Val "C" allele frequencies ranging from 0.088 to 0.189 and IVS1-728G>A "A" allele frequency ranging from 0.261 to 0.411 in the study populations. The genotypes and haplotypes showed wide variation among populations. There is no strong and significant linkage disequilibrium (LD) between these polymorphisms. Comparison of the data with HapMap world populations also reflected the similar LD patterns. The variations that observed in CYP1A1 allelic distribution may presumably due to geographically determined selection pressures. In conclusion, our results provide a solid base for the future association studies on the relevance of CYP1A1 variants in response to drugs that are substrates of CYP1A1. Source


Murthy J.,Sri Ramachandra University | Lakkakula S.,Sri Venateswara University | Gurramkonda V.B.,Sri Ramachandra University | Pathapati R.M.,Narayana Medical College | And 2 more authors.
Cleft Palate-Craniofacial Journal | Year: 2015

Introduction: Nonsyndromic cleft lip with or without cleft palate (NSCLP) is a common birth defect with substantial clinical and social impact. Folate deficiency is one of the factors that have been associated with increased risk for NSCLP. Polymorphisms in folate and homocysteine pathway genes may act as susceptibility factors. Objective: The objective of this study was to evaluate prevalence estimates of cystathionine beta-synthase (CBS) insertion of 68-bp (c.844ins68) polymorphisms and their correlation with NSCLP. Material and Methods: A total of 236 unrelated individuals from seven Indian populations and an additional 355 cases with NSCLP and 357 controls without NSCLP were included in this study. We investigated the CBS c.844ins68 polymorphism in all samples. Genotyping was performed with polymerase chain reaction and electrophoresis. The data were statistically analyzed using the chi-square test. Results: The CBS c.844ins68 allele is present in six of the seven populations analyzed, and allele frequencies range from 1.5% in Balija to 9.1% in Sugali populations. The CBS c.844ins68 polymorphism showed a significant protective effect on NSCLP at both genotype (WW versus WI: odds ratio [OR] = 0.54, 95% confidence interval [CI] = 0.31 to 0.95, P = .149) and allele levels (W versus I: OR = 0.56, 95% CI = 0.32 to 0.96, P = .033). Conclusions: The current study observed significant differences in the frequency of the CBS 844ins68 allele across populations. There is a significant association between CBS c.844ins68 polymorphism and cleft lip and palate in the Indian population. Additional studies are warranted to identify the functional variants in the genes controlling homocysteine as etiological contributors to the formation of oral clefts. Source

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