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Biomedical subjects

K Das

Publications and source records attributed to K Das.

At least 19 recordsLinked to original sources
PubMed2007

A randomized controlled trial of lamivudine to treat acute hepatitis B.

UNLABELLED: The role of antivirals in patients with acute viral hepatitis B (AVH-B) has not been evaluated in controlled trials. The aim of this study was to evaluate the efficacy of lamivudine in patients with AVH-B. AVH-B patients with serum bilirubin of more than 5 mg/dL were randomized to receive either 100 mg of lamivudine daily for 3 months (group 1, n = 31) or placebo (group 2, n = 40). Patients were considered to have severe AVH-B if they fulfilled 2 of 3 criteria: (1) hepatic encephalopathy; (2) serum bilirubin > or = 10.0 mg/dL; and (3) international normalized ratio (INR) > or = 1.6. At week 4, HBV DNA levels were significantly lower (P = 0.037) in group 1 (median: 3.6721 log copies/mL) than group 2 (median: 4.2721 log copies/mL). Thereafter, HBV DNA levels were comparable in the 2 groups. The improvement in serum bilirubin, ALT, and INR values was similar in the 2 groups. Twenty-two patients (71%) in group 1 and 25 patients (62.5%) in group 2 had severe AVH-B. Results were similar when patients with severe AVH-B were analyzed separately. After 12 and 18 months, 93.5% and 92.5%, respectively, of patients in the lamivudine group and 96.7% and 97.5%, respectively, of patients in the placebo group lost HBsAg. There were no deaths in either group. After 1 year, 21 patients (67.7%) in group 1 and 34 patients (85%) in group 2 developed protective anti-HBs titers (P = 0.096). All HBeAg-positive patients in both groups lost e antigen and anti-HBe developed in 71% and 87.5% of patients in groups 1 and 2, respectively (P = 0.132). CONCLUSION: Though lamivudine causes a greater decrease in levels of HBV DNA, it does not cause significantly greater biochemical and clinical improvement as compared to placebo in patients with acute hepatitis B.

Acute Disease↗
PubMed2007

Differential utilization of pyrene as the sole source of carbon by Bacillus subtilis and Pseudomonas aeruginosa strains: role of biosurfactants in enhancing bioavailability.

AIMS: Our goal is to compare the efficiency of utilization of pyrene as the sole source of carbon for growth and energy by two nonactinomycetous groups of bacteria viz., Bacillus subtilis DM-04 and Pseudomonas aeruginosa mucoid (M) and nonmucoid (NM) strains, isolated from a petroleum-contaminated soil sample of north-east India. METHODS AND RESULTS: Bacillus subtilis DM-04 and P. aeruginosa M and NM bacterial strains were capable of secreting biosurfactant in the culture medium while growing on pyrene and their pyrene utilizing efficiency was demonstrated by correlating the bacterial growth in the presence of pyrene as the sole source of carbon along with a concomitant decrease in pyrene content from the culture medium with respect to time. The biosurfactant secreted by the respective bacterial strains enhanced the apparent solubility of pyrene by factors of 5-7 and influenced the bacterial cell surface hydrophobicity resulting in higher uptake and utilization of pyrene by bacteria. The growth of B. subtilis DM-04 and P. aeruginosa M and NM strains at the expense of pyrene after 96 h showed an assimilation of about 48.0 +/- 1.1% (mean +/- SD) and 32.0 +/- 0.6% (mean +/- SD) of pyrene carbon, respectively, showing differences in metabolism of pyrene by these bacterial strains. CONCLUSIONS: Bacillus subtilis DM-04 strain exhibited higher utilization and cellular assimilation of pyrene compared with P. aeruginosa M and NM strains. Further, the biosurfactants produced by the bacteria under study are capable of enhancing the solubility of pyrene in aqueous media and can influence the cell surface hydrophobicity of the biosurfactant-producing strains that results in a higher uptake of pyrene. SIGNIFICANCE AND IMPACT OF THE STUDY: It may be suggested that the bacteria used in this study are suitable candidates for practical field application for effective in situ bioremediation of pyrene-contaminated sites.

Bacillus subtilis↗
PubMed2006

Prevalence of beta-thalassaemia in subcastes of Indian Sindhis: Results from a two-phase survey.

OBJECTIVE: To estimate the prevalence of beta-thalassaemia in different subcastes of the Indian Sindhi population who, in general, have a high prevalence of this disease. STUDY DESIGN: A two-phase, community-based survey. METHODS: Asymptomatic, Sindhi volunteers from Nagpur, central India, were recruited into the present study over a 7-year period. The first phase included the use of the Naked Eye Single Tube Red cell Osmotic Fragility Test (NESTROFT). Those positive for NESTROFT or those volunteering for haemoglobin A(2) (HbA(2)) quantification entered the second phase of the survey. Appropriate statistical methods for estimating prevalence from two-phase surveys were used. RESULTS: The prevalence of beta-thalassaemia carriers across the five major Sindhi subcastes varied substantially in the study population. Larkana Sindhis had the highest (17%) whereas Dadu Sindhis had the lowest (8%) frequency of the beta-thalassaemia allele. As a corollary, the projected incidence of beta-thalassaemia major in newborn babies greatly varied by the subcastes of the parents. CONCLUSION: Ethnic subgroups within populations known to commonly carry the beta-thalassaemia gene provide further information that is useful from epidemiological and public health perspectives.

Adolescent↗
PubMed2006

Nontraumatic spinal epidural hematoma associated with clopidogrel.

A 73-year-old female treated with clopidogrel for vascular disease presented with sudden onset of back pain, urinary retention and paraplegia. MRI scans demonstrated a thoracolumbar epidural hematoma and the patient underwent emergency laminectomy for evacuation of the hematoma. A possible causal link between clopidogrel and occurrence of the hemorrhage is discussed and the literature on spontaneous spinal hematomas is reviewed.

Aged↗
PubMed2006

Microstructure and deformation behavior of biocompatible TiO2 nanotubes on titanium substrate.

Titanium oxide coatings have been shown to exhibit desirable properties as biocompatible coatings. We report on the quantitative microstructure characterization and deformation behavior of TiO(2) nanotubes on Ti substrate. Nanotubes were processed using anodic oxidation of Ti in a NaF electrolyte solution. Characterization of the as-processed coatings was conducted using scanning electron microscopy and focused ion beam milling. Increases in anodization time had no significant effect on tube diameter or tube wall thickness. Coating thickness, however, increased with time up to 2h of anodization, at which point an equilibrium thickness was established. Nanoindentation was used to probe the mechanical response in terms of Young's modulus and hardness. Progressively higher values of elastic modulus were obtained for thinner films consistent with increasing effects of the Ti substrate. A possible deformation mechanism of densification of the porous oxide and wear of the dense surface is suggested and discussed.

Biomechanical Phenomena↗
PubMed2006

Azimuthal angle correlations for rapidity separated Hadron pairs in d+Au collisions at square root of sNN=200 GeV.

Deuteron-gold (d+Au) collisions at the Relativistic Heavy Ion Collider provide ideal platforms for testing QCD theories in dense nuclear matter at high energy. In particular, models suggesting strong saturation effects for partons carrying small nucleon momentum fraction (x) predict modifications to jet production at forward rapidity (deuteron-going direction) in d+Au collisions. We report on two-particle azimuthal angle correlations between charged hadrons at forward/backward (deuteron/gold going direction) rapidity and charged hadrons at midrapidity in d+Au and p+p collisions at square root of sNN=200 GeV. Jet structures observed in the correlations are quantified in terms of the conditional yield and angular width of away-side partners. The kinematic region studied here samples partons in the gold nucleus with x~0.1 to ~0.01. Within this range, we find no x dependence of the jet structure in d+Au collisions.

Journal Article↗
PubMed2006

Genetic variation of 13 STR loci in the four endogamous tribal populations of Eastern India.

We have analysed 13 autosomal STR loci in four endogamous tribal populations from two eastern states (Orissa and Nagaland) of India. The Gadaba, Kuvi Khond and Lotha Naga populations have not been analysed for microsatellite genetic variation previously. The allele frequencies for all loci are within the range observed in the geographical region and racial background, though some alleles showed greater variation. Departures from the Hardy-Weinberg equilibrium were tested by three methods and two loci (THO1 and TPOX) showed significant departures for all measures in Gadaba and Lotha Naga populations. The exclusion probability and discrimination probability were high for all analysed loci in all populations. There is no evidence for association of alleles among the STR loci studied. This allele frequency information will be useful for forensic, paternity and population genetic studies.

DNA Fingerprinting↗
PubMed2006

Hydrogen bonding properties of Coumarin 151, 500, and 35: the effect of substitution at the 7-amino position.

The steady-state spectral properties (absorption and emission) of three structurally similar Coumarin dyes, C151, C500, and C35 were investigated in 13 different solvents. A Kamlet-Taft (KT) analysis of the spectral peak frequencies reveals that, in addition to polarity, hydrogen bonding between the carbonyl oxygen and a protic solvent in the excited state imparts maximum stabilization for C151 and minimum for C35, while that for C500 lies in between. The spectral properties of the three dyes in two solvents, chloroform and THF, which have similar polarity in the KT scale but have only hydrogen-bond donor (chloroform) and hydrogen-bond acceptor (THF) properties, are seen to be sensitive to the substitution pattern at the 7-amino position. In addition, a slow emission spectral relaxation is observed for C151 and C500 having a time constant of approximately 500 ps in chloroform. For C35 this was too fast to be detected by the time resolution of our setup. The exact reason for this slow spectral relaxation in chloroform is unclear at present, and further studies are needed to understand clearly the structural effects on the hydrogen bonding dynamics of these dyes.

Chloroform↗
PubMed2006

J/psi production and nuclear effects for d + Au and p + p collisions at square root of S(NN) = 200 GeV.

J/psi production in d + Au and p + p collisions at square root of S(NN) = 200 GeV has been measured by the PHENIX experiment at rapidities -2.2 < y < +2.4. The cross sections and nuclear dependence of J/psi production versus rapidity, transverse momentum, and centrality are obtained and compared to lower energy p + A results and to theoretical models. The observed nuclear dependence in d + Au collisions is found to be modest, suggesting that the absorption in the final state is weak and the shadowing of the gluon distributions is small and consistent with Dokshitzer-Gribov-Lipatov-Altarelli-Parisi-based parametrizations that fit deep-inelastic scattering and Drell-Yan data at lower energies.

Journal Article↗
PubMed2005

Saturation of azimuthal anisotropy in Au + Au collisions at (square root)s(NN) = 62-200 GeV.

New measurements are presented for charged hadron azimuthal correlations at midrapidity in Au+Au collisions at (square root)s(NN) = 62.4 and 200 GeV. They are compared to earlier measurements obtained at (square root)s(NN) = 130 GeV and in Pb + Pb collisions at (square root)s(NN) = 17.2 GeV. Sizeable anisotropies are observed with centrality and transverse momentum (pT) dependence characteristic of elliptic flow (upsilon2). For a broad range of centralities, the observed magnitudes and trends of the differential anisotropy, upsilon2(pT), change very little over the collision energy range (square root)s(NN) = 62-200 GeV, indicating saturation of the excitation function for upsilon2 at these energies. Such a saturation may be indicative of the dominance of a very soft equation of state for (square root)s(NN) approximately 60-200 GeV.

Journal Article↗
PubMed2005

Nuclear modification factors for hadrons at forward and backward rapidities in deuteron-gold collisions at sqrt[s(NN)]=200 GeV.

We report on charged hadron production in deuteron-gold reactions at sqrt[s(NN)]=200 GeV. Our measurements in the deuteron direction cover 1.4<eta<2.2, referred to as forward rapidity, and in the gold direction -2.0<eta<-1.4, referred to as backward rapidity, and a transverse momentum range p(T)=0.5-4.0 GeV/c. We compare the relative yields for different deuteron-gold collision centrality classes. We observe a suppression relative to binary collision scaling at forward rapidity, sensitive to low momentum fraction (x) partons in the gold nucleus, and an enhancement at backward rapidity, sensitive to high momentum fraction partons in the gold nucleus.

Journal Article↗
PubMed2005

Feeding ecology of five commercial shark species of the Celtic Sea through stable isotope and trace metal analysis.

In order to trace their feeding habits, stable carbon and nitrogen isotope ratios (delta15N and delta13C), as well as trace metal concentrations (Zn, Cd, Fe, Cu, Se and Hg) were analysed in the tissues of five commercial shark species from the Celtic Sea: the tope shark Galeorhinus galeus, the black-mouthed catshark Galeus melastomus, the starry smooth hound Mustelus asterias, the spiny dogfish Squalus acanthias and the lesser-spotted dogfish Scyliorhinus canicula. Our results were compared to previously described stomach contents and isotopic composition of potential preys. Isotopic ratio delta15N suggested that tope sharks fed at a higher trophic level (16.7 per thousand in the muscle) than the other species, reflecting its piscivorous diet. The lower values of spiny dogfish (11.6 per thousand in the muscle) might be explained, amongst other things, by either its migratory behaviour or its preference for preys from lower trophic levels. Cd and Hg were correlated with isotopic ratios delta13C and delta15N, and were shown to be diet-related whereas Zn, Fe and Cu seemed much more linked to species-specific metabolism. Although this multidisciplinary approach is revealed as a useful tool for the study of shark ecology, the lack of known trophic fractionation suggests that isotopic data be compared to traditional diet analyses.

Animals↗
PubMed2005

Chromosomal changes in prostate cancer: a fluorescence in situ hybridization study.

The incidence of prostate cancer (PC) is increasing steadily with the aging population in Singapore. As the pattern of chromosomal aberrations in Asian men with PC is poorly understood, we investigated the numerical aberrations for chromosomes 7, 8, 11, and 17 by fluorescence in situ hybridization (FISH). FISH was performed on standard sections and tissue microarrays of 54 PC and 33 benign prostatic hyperplasia (BPH) specimens. Among the 54 PC specimens, FISH detected 44 cases as aneusomy and two as disomy and was unsuccessful for eight cases. Cytogenetic alterations of two or more chromosomes per tumor were detected in 33/46 (72%) PCs. The most frequent alteration was aneusomy of chromosome 8 detected in 34/46 (74%) cases followed by numerical aberrations in chromosome 7 (61%). Gain of 8q24, loss of chromosome 7, and gain of 11q13 were associated with higher Gleason score and were statistically significant. Gain of chromosome 7 was more common in locally advanced disease, while gain of chromosome 11q13 and chromosome 7 was more common in metastatic disease.

Adult↗
PubMed2005

Non-alcoholic steatohepatitis.

Non-alcoholic steatohepatitis (NASH) represents only a part of a wide spectrum of non-alcoholic fatty liver disease (NAFLD) and its prevalence is only 2 - 3% in the general population. Obesity, diabetes, hyperlipidemia and female sex are important risk factors for NASH. Two hit theory describes very well the pathogenesis of NASH wherein hepatic steatosis, the first hit is followed up by the second hit, one of which may be reactive oxygen species. Mitochondria is the main source of reactive oxygen species which may trigger steatohepatitis by lipid peroxidation, cytokine induction or induction of fas-ligand. Insulin resistance syndrome is the only metabolic syndrome that has been consistently associated with NASH. The diagnosis rests on the hallmark histological features and rigorous exclusion of significant alcohol consumption. Most patients are asymptomatic, have mild-to-moderate elevations of serum aminotransferase levels, clinical hepatomegaly and features of fatty liver on imaging. Liver biopsy is essential for positive diagnosis and prognostication of NASH. Histologically, fat deposition is typically macrovesicular and inflammation of steatohepatitis is predominantly lobular. Neutrophilic cells in lobular inflammatory infilterate are a distinguishing feature of steatohepatitis and differentiate it from other chronic hepatitis. The pattern of collagen deposition is perivenular & peri-sinusoidal spaces in zone 3. NASH is a progressive disease in more than one in four and has spontaneous regression in less than one in six. Therapy options include weight reduction in obese, good control in diabetics and exercise. Ursodeoxycholic acid has membrane stabilizing, cytoprotective and immunological effect and normalizes raised transaminases. Liver transplantation has been done in NASH but transplanted liver shows re-development in more than two thirds. Many more therapies are in the pipeline and show promise for the future.

Adult↗
PubMed2004

Double helicity asymmetry in inclusive midrapidity pi0 production for polarized p+p collisions at square root s = 200 GeV.

We present a measurement of the double longitudinal spin asymmetry in inclusive pi(0) production in polarized proton-proton collisions at sqrt[s]=200 GeV. The data were taken at the Relativistic Heavy Ion Collider with average beam polarizations of 0.27. The measurements are the first in a program to study the longitudinal spin structure of the proton, using strongly interacting probes, at collider energies. The asymmetry is presented for transverse momenta 1-5 GeV/c at midrapidity, where next-to-leading-order perturbative quantum chromodynamic (NLO pQCD) calculations well describe the unpolarized cross section. The observed asymmetry is small and is compared to a NLO pQCD calculation with a range of polarized gluon distributions.

Journal Article↗
PubMed2004

Pediatric tracheostomy: a 13-year experience.

Pediatric tracheostomy has been reported to be a surgical procedure with significant morbidity and mortality. The use of tracheostomy in airway management has changed over time as regards indication and outcome. A review of the last 13 years' experience in our institution was carried out to focus on this group of patients and the recent trends in airway management. A retrospective analysis of hospital records was done and information collected with respect to age, gender, indication for tracheostomy, duration, complications, and follow-up. Thirty-nine tracheotomies were done in 36 patients, of whom males outnumbered females 2:1. The mean patient age was 41.6 months while nearly a third were newborns. The indications were congenital and acquired obstructive lesions. Apart from nine cases, all have been treated and decannulated. Follow-up ranged from 1 month to 8 years, and decannulation time from 48 h to 45 months. Home tracheostomy care was very well managed by the parents. One tracheostomy-related death was encountered. Complications were minor and transient and occurred post-decannulation in our series, in contrast to the major complications, both acute and chronic, reported in the literature. More neonates and infants are undergoing tracheostomy and surviving. Pediatric tracheostomy is a safe procedure with home care by parents feasible.

Child↗