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S Das

Publications and source records attributed to S Das.

At least 73 records · Page 4Linked to original sources
PubMed2004

Purification, substrate specificity, and N-terminal amino acid sequence analysis of a beta-lactamase-free penicillin amidase from Alcaligenes sp.

A beta-lactamase-free penicillin amidase from Alcaligenes sp. active against various beta-lactams was purified to homogeneity. The enzyme can hydrolyze penicillin G to 6-amino penicillanic acid (6-APA) and furnish penicillin G from 6-APA and phenyl acetic acid by condensation. The penicillin amidase is a heterodimer of subunit masses of 63 kDa and 22 kDa, respectively. Its isoelectric point is at pH 8.5. Cephalothin was found to be the best substrate. This is a novel type II penicillin amidase which shares the properties of both type II and type III enzymes. It is thermostable and, unlike penicillin amidase from A. faecalis, its stability remains unperturbed even in presence of reductant. An inhibition study by 2-hydroxy-5-nitro benzylbromide indicated the involvement of tryptophan in catalysis by the enzyme.

Alcaligenes↗
PubMed2004

Multistrange baryon production in Au-Au collisions at sqrt[s(NN)]=130 GeV.

The transverse mass spectra and midrapidity yields for Xis and Omegas are presented. For the 10% most central collisions, the (-)Xi(+)/h(-) ratio increases from the Super Proton Synchrotron to the Relativistic Heavy Ion Collider energies while the Xi(-)/h(-) stays approximately constant. A hydrodynamically inspired model fit to the Xi spectra, which assumes a thermalized source, seems to indicate that these multistrange particles experience a significant transverse flow effect, but are emitted when the system is hotter and the flow is smaller than values obtained from a combined fit to pi, K, p, and Lambdas.

Journal Article↗
PubMed2004

Cross sections and transverse single-spin asymmetries in forward neutral-pion production from proton collisions at sqrt[s]=200 GeV.

Measurements of the production of forward high-energy pi(0) mesons from transversely polarized proton collisions at sqrt[s]=200 GeV are reported. The cross section is generally consistent with next-to-leading order perturbative QCD calculations. The analyzing power is small at x(F) below about 0.3, and becomes positive and large at higher x(F), similar to the trend in data at sqrt[s]< or =20 GeV. The analyzing power is in qualitative agreement with perturbative QCD model expectations. This is the first significant spin result seen for particles produced with p(T)>1 GeV/c at a polarized proton collider.

Journal Article↗
PubMed2004

Identified particle distributions in pp and Au+Au collisions at square root of (sNN)=200 GeV.

Transverse mass and rapidity distributions for charged pions, charged kaons, protons, and antiprotons are reported for square root of [sNN]=200 GeV pp and Au+Au collisions at Relativistic Heary Ion Collider (RHIC). Chemical and kinetic equilibrium model fits to our data reveal strong radial flow and long duration from chemical to kinetic freeze-out in central Au+Au collisions. The chemical freeze-out temperature appears to be independent of initial conditions at RHIC energies.

Journal Article↗
PubMed2004

Rho0 production and possible modification in Au+Au and p+p collisions at square root [sNN] = 200 GeV.

We report results on rho(770)(0)-->pi(+)pi(-) production at midrapidity in p+p and peripheral Au+Au collisions at sqrt[s(NN)]=200 GeV. This is the first direct measurement of rho(770)(0)-->pi(+)pi(-) in heavy-ion collisions. The measured rho(0) peak in the invariant mass distribution is shifted by approximately 40 MeV/c(2) in minimum bias p+p interactions and approximately 70 MeV/c(2) in peripheral Au+Au collisions. The rho(0) mass shift is dependent on transverse momentum and multiplicity. The modification of the rho(0) meson mass, width, and shape due to phase space and dynamical effects are discussed.

Journal Article↗
PubMed2004

Monitoring methotrexate-induced hepatic fibrosis in patients with psoriasis: are serial liver biopsies justified?

BACKGROUND: Reports that up to 26% of subjects with psoriasis develop cirrhosis have led to a recommendation of serial liver biopsies after each cumulative dose of 1500 mg of methotrexate. AIM: To evaluate the progression of liver injury in patients with psoriasis and the impact of monitoring by liver biopsy on their management. METHODS: One hundred and twenty-one liver biopsies from 66 subjects (aged 11-79 years) with psoriasis, receiving a median cumulative dose of 3206 mg of methotrexate over a period of 280.5 weeks, were evaluated. RESULTS: The assessment of advanced fibrosis according to the Ishak system (>or= 4) correlated perfectly with that of the Scheuer system (>or= 3) and poorly with that of the Roenigk scale (>or= 3b) (r2 = 1.0 and 0.31, respectively). Two of 24 pre-treatment biopsies showed advanced fibrosis and both subjects were heavy drinkers. The cumulative probabilities of advanced fibrosis (Ishak >or= 4) were 0%, 2.6%, 2.6%, 8.2% and 8.2% at cumulative doses of 1500, 3000, 4500, 5000 and 6000 mg, respectively. None of the subjects developed cirrhosis during follow-up or discontinued therapy on the basis of liver biopsy findings. CONCLUSIONS: Advanced hepatic fibrosis with low-dose methotrexate therapy is much less frequent than previously reported. Pre-treatment or monitoring liver biopsies in accordance with the current guidelines have little impact on patient management.

Adolescent↗
PubMed2004

Azimuthal anisotropy at the relativistic heavy ion collider: the first and fourth harmonics.

We report the first observations of the first harmonic (directed flow, v(1)) and the fourth harmonic (v(4)), in the azimuthal distribution of particles with respect to the reaction plane in Au+Au collisions at the BNL Relativistic Heavy Ion Collider (RHIC). Both measurements were done taking advantage of the large elliptic flow (v(2)) generated at RHIC. From the correlation of v(2) with v(1) it is determined that v(2) is positive, or in-plane. The integrated v(4) is about a factor of 10 smaller than v(2). For the sixth (v(6)) and eighth (v(8)) harmonics upper limits on the magnitudes are reported.

Journal Article↗
PubMed2004

Particle-type dependence of azimuthal anisotropy and nuclear modification of particle production in Au+Au collisions at square root of sNN=200 GeV.

We present STAR measurements of the azimuthal anisotropy parameter v(2) and the binary-collision scaled centrality ratio R(CP) for kaons and lambdas (Lambda+Lambda) at midrapidity in Au+Au collisions at square root of s(NN)=200 GeV. In combination, the v(2) and R(CP) particle-type dependencies contradict expectations from partonic energy loss followed by standard fragmentation in vacuum. We establish p(T) approximately 5 GeV/c as the value where the centrality dependent baryon enhancement ends. The K(0)(S) and Lambda+Lambda v(2) values are consistent with expectations of constituent-quark-number scaling from models of hadron formation by parton coalescence or recombination.

Journal Article↗
PubMed2004

Phylogenetic conservation of the stem-loop III structure of the 5' untranslated region of Hepatitis C virus RNA among natural variants in samples collected from Southern India.

The stem-loop III (SLIII) structure within the 5' untranslated region has been shown to be critical for internal initiation of translation of Hepatitis C virus (HCV). Using 'Single Strand Conformation Polymorphism (SSCP)' of the SLIII region we have investigated for natural mutations and demonstrated presence of some non-covariant changes in certain sub-domains. However, overall SLIII-RNA structure was found to be phylogenetically conserved. Additionally, by SSCP analysis we have determined the genotype of 50 HCV isolates collected from Southern India, 25 random samples were confirmed by DNA sequencing. Results showed the prevalence of genotype 1 in this part of India.

5' Untranslated Regions↗
PubMed2004

The burden of diabetes and impaired fasting glucose in India using the ADA 1997 criteria: prevalence of diabetes in India study (PODIS).

This random multistage cross sectional population survey was undertaken to determine the prevalence of diabetes mellitus (DM) and impaired fasting glycemia/glucose (IFG) in subjects aged 25 years and above in India. The study was carried out in 108 centers (49 urban and 59 rural) to reflect the size and heterogeneity of the Indian population. 41,270 (20,534 males and 20,736 females) subjects were studied. 21,516 (10,865 males and 10,651 females) were from urban areas and 19,754 (9669 males and 10,085 females) from rural areas. Blood samples were taken after a fast of 10-12h and the subjects were categorized as having IFG or DM using the 1997 American Diabetes Association criteria. The age and gender standardized prevalence rate for DM and IFG in the total Indian population was 3.3 and 3.6% respectively (P < 0.001). The standardized prevalence of DM and IFG in urban areas was significantly higher than that for the rural population (urban DM prevalence 4.6% versus rural DM prevalence 1.9%, P < 0.001; urban IFG prevalence 4.8% versus rural IFG prevalence 2.5%, P < 0.001). There was no statistically significant difference in the prevalence between DM (4.6%) and IFG (4.8%) in the urban population. The rural prevalence of IFG (2.5%) was significantly (P <0.001) more than the rural prevalence of DM (1.9%). Type 2 diabetes is a major health problem is India.

Adult↗
PubMed2004

The burden of diabetes and impaired glucose tolerance in India using the WHO 1999 criteria: prevalence of diabetes in India study (PODIS).

This random multistage cross-sectional population survey was undertaken to determine the prevalence of diabetes mellitus (DM) and impaired glucose tolerance (IGT) in subjects aged 25 years and above in India. The study was carried out in 77 centers (40 urban and 37 rural). 18363 (9008 males and 9355 females) subjects were studied. 10617 (5379 males and 5238 females) were from urban areas and 7746 (3629 males and 4117 females) from rural areas. Blood samples were taken after a fast of 10-12 h and 2 h after 75 g of oral glucose. Subjects were categorized as having IGT or DM using the World Health Organisation (WHO) (1999) criteria. The standardized prevalence rate for DM in the total Indian, urban and rural populations was 4.3, 5.9 and 2.7%, respectively. The corresponding IGT rates in the three populations was 5.2, 6.3 and 3.7%, respectively. The urban prevalence of DM and IGT was significantly greater than in the rural population (P < 0.001 in both instances). The prevalence of DM was significantly, more than that of IGT (P < 0.001) within both the rural and urban populations. Type 2 diabetes is a major health problem is India.

Adult↗
PubMed2004

Comparing the ADA 1997 and the WHO 1999 criteria: Prevalence of Diabetes in India Study.

This random multistage cross-sectional population survey was undertaken to determine the prevalence of type 2 diabetes mellitus (DM) in subjects aged 25 years and above in India. The study was carried out in 77 centres (42 urban and 35 rural) to reflect the size and heterogeneity of the Indian population. 18,363 (9008 male and 9355 female) subjects were studied. 10,617 (5379 males and 5238 females) were from urban areas and 7746 (3629 males and 4117 females) from rural areas. Blood samples were taken after a fast of 10-12 and 2 h after 75 g of oral glucose. Subjects were categorized as having impaired fasting glycemia (IFG) or DM using the 1997 ADA or having impaired glucose tolerance (IGT) or DM using the 1999 WHO criteria. The age- and gender-standardized prevalence rate for DM using the ADA criteria was 3.6% whilst that using the WHO criteria was 4.3% (P < 0.001). The respective standardized prevalence of DM, using the two criteria was, 4.7 and 5.6%, respectively (P < 0.001) in the urban Indian population and 2.0 and 2.7% (P < 0.02) in the rural Indian population. Using the WHO criteria, 581 subjects were newly diagnosed whilst the ADA criteria newly diagnosed 437 subjects. The respective numbers for the urban population were 425 and 323, and for the rural population were 146 and 114, respectively. The ADA criteria could diagnose 75.2, 76.0 and 73.0% of the subjects who had DM as per the WHO criteria. Of 739 Indian subjects who had IFG, 106 (14.3%) were diagnosed as having DM by the WHO criteria whilst 505 (68.3%) had values compatible with a diagnosis of IGT. Of the 536 urban subjects with IFG, 74 (13.8%) had DM and 350 (65.3%) had IGT using the WHO criteria. Of the 302 rural subjects with IFG, 32 (15.8%) had DM and 155 (76.3%) had IGT using the WHO criteria. 505 (49.9%) of 1012 Indian subjects with IGT as per the WHO criteria had IFG. 350 (47.7%) of 733 urban subjects and 155 (55.5%) of 279 rural subjects with IGT had values compatible with IFG as per the ADA criteria. Type 2 diabetes is a major health problem is India. The use of the ADA criteria would underestimate the prevalence of DM by not diagnosing subjects showing a poor response to a glucose challenge. This along with the discrepancies between subjects showing IGF or IGT could be a challenge to any prevention program.

Adult↗
PubMed2004

Inhibition of DMBA/croton oil-induced two-stage mouse skin carcinogenesis by diphenylmethyl selenocyanate.

Selenium, an essential micronutrient, is associated with antioxidant functions, physiological defence mechanisms against different diseases including several types of cancers. Search for new selenium compounds with more chemopreventive activities and lesser toxicities are in progress. In the present study, the antioxidative roles of a synthetic organoselenium compound, diphenylmethyl selenocyanate, were evaluated against 7,12-dimethylbenz(a)anthracene (DMBA)/croton oil-induced two-stage mouse skin carcinogenesis model. The compound was administered orally in carcinogen-induced mice in two different non-toxic doses: 2 mg/kg body weight and 3 mg/kg body weight. Significant inhibition in the incidence of papilloma formation (58-80%) as well as in the cumulative number of papilloma per papilloma-bearing mouse were observed in the treated groups as compared with the carcinogen control group. The compound was also found to significantly upregulate different phase II detoxifying enzymes in liver cytosol such as glutathione-S-transferase (P<0.01), catalase (P<0.01) and superoxide dismutase (SOD) (P<0.01) when measured after 15 days and also after 12 weeks of first DMBA treatment. Lipid peroxidation measured as the thiobarbituric acid reactive substances in liver microsomes was significantly inhibited (P<0.05) in a dose-dependent manner by diphenylmethyl selenocyanate. Thus the compound exerts its chemopreventive activity by reducing papilloma formation during chemically induced carcinogenesis, which in turn, may be through modulating the level of lipid peroxidation and phase II detoxifying enzyme system at the doses evaluated.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2004

Provocation testing in polymorphic light eruption using fluorescent ultraviolet (UV) A and UVB lamps.

BACKGROUND: Provocation testing is frequently performed during investigation of patients with suspected polymorphic light eruption (PLE). Techniques are not standardized between centres. OBJECTIVES: We sought to evaluate the efficacy of different fluorescent ultraviolet (UV) radiation lamps for provocation testing in PLE. METHODS: We analysed results in 68 patients referred consecutively for phototesting in whom a diagnosis of PLE seemed likely based on clinical history. Patients' case notes were reviewed and responses recorded to provocation testing on forearm skin over three consecutive days using broadband UVA, narrowband and broadband UVB lamps. RESULTS: A positive papular response to broadband UVA exposure was seen in 38 patients [56%, estimated 95% population confidence interval (CI) 43-67.9]. Thirty-four patients (50%) had a positive papular response to narrowband UVB exposure (95% CI 37.6-62.4). The probability of a positive provocation test following irradiation with both lamps was 80.9% (95% CI 69.5-89.4). From April 1999, 34 patients also had provocation testing with broadband UVB. Although six patients (18%) had a positive papular response, they all showed a positive response to one or both of the other lamp types. CONCLUSIONS: Provocation testing with fluorescent UVA and UVB lamps is a cheap and readily available method that can be used as a diagnostic aid to investigate patients with suspected PLE. Using both broadband UVA and narrowband UVB lamps for testing increases the likelihood of confirming the diagnosis than if either lamp is used alone.

Adolescent↗