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Biomedical subjects

A Ghosh

Publications and source records attributed to A Ghosh.

At least 19 recordsLinked to original sources
PubMed2006

Transport properties of CdS nanowire embedded poly(3-hexyl thiophene) nanocomposite.

Electrical transport properties of CdS nanowire embedded regioregular poly(3-hexyl thiophene) (P3HT) nanocomposite are investigated and the results are compared with those of the pure P3HT polymer. Both dc and ac conductivities of P3HT and CdS-P3HT nanocomposites show semiconducting nature and conductivity of CdS-P3HT is much less than that of the pure P3HT conducting polymer. The difference in the electrical behavior is attributed to the formation of nanowires in the CdS-P3HT nanocomposite. The dc conductivity data at high and low temperatures are qualitatively consistent with the optical-photon-assisted hopping and variable-range hopping models, respectively. However, the multiphonon-assisted hopping models of small polarons in nonadiabatic regime, which consider strong interactions with electrons with the optical as well as acoustical phonons, are the best to interpret quantitatively the experimental data in the entire temperature range for both P3HT and CdS-P3HT nanocomposites. We observe that the quantum tunneling model of small polarons is consistent with almost every respect of the loss data of P3HT conducting polymer, while for CdS-P3HT nanocomposite the ac conductivity varies with temperature in a different manner, which is explained in terms of simple quantum tunneling model of electrons in contrast to that of pure P3HT conducting polymer.

Journal Article↗
PubMed2006

Comparison of anthropometric, metabolic and dietary fatty acids profiles in lean and obese dyslipidaemic Asian Indian male subjects.

OBJECTIVES: To compare obesity measures, metabolic profiles and dietary fatty acids in lean and obese dyslipideamic Asian Indian male subjects. DESIGN: Cross-sectional. SETTINGS: Asian Indians living in the eastern part of India. SUBJECTS: One hundred and thirty (Group I: lean control, n=50; Group II: lean dyslipidaemic, n=40 and Group III: obese dyslipidaemic, n=40) Asian Indian male subjects (> or =30 years) living in the eastern part of India. METHODS: Anthropometric measures namely height, weight, circumferences of waist (WC) and hip, lipids (total cholesterol (TC) and triglycerides (TG)), lipoproteins (high- (HDL) and low-density lipoproteins (LDL)), fasting plasma glucose (FPG) and dietary fatty acids were obtained from each participant. Obesity measures, that is, body mass index (BMI), waist-hip ratio (WHR) and conicity index (CI) were subsequently calculated from anthropometric measures. Obesity was defined as individuals having BMI> or =25 kg/m(2). SUBJECTS with one or more of the following conditions were considered as dyslipidaemic: TG> or =2.3 mmol/l, TC> or =6.2 mmol/l, or TC/HDL> or =4.4 mmol/l. Daily intake of nutrients as well as saturated (SFA), monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA) were estimated by adding together all the foodstuffs consumed on weekly and monthly manner. Conversion of foodstuffs into nutrients was performed according to standard nutritive values of Indian foodstuffs. RESULTS: Analysis of variance with Scheffe's post hoc test revealed that Group I had significantly lower mean compared to both Group II and Group III for age, WC, WHR, CI, TC, TG, LDL, FPG, total carbohydrates intake and intake of trans fatty acids. On the other hand, Group I had significantly lower mean than Group III only for BMI as well as intake of total proteins, total fats, total energy and erucic acids. Although, Group I had significantly greater mean compared to both Group II and Group III for HDL, UFA/SFA, MUFA/SFA and PUFA/SFA. Pearson's partial correlations (controlling for age and total energy) revealed that central obesity measures (WC, WHR and CI) had significant association with dietary fatty acids and their ratios. Furthermore, partial correlations (controlling for age) also showed that the ratios of unsaturated to SFA had significant negative association with lipids, lipoproteins (except HDL) and plasma glucose. Discriminant function analysis revealed that overall 78% of all entries were positively (correctly) classified in three groups using fatty acids and their ratios. CONCLUSION: It seems rational to argue that while dealing with dyslipidaemic Asian Indians, clinicians should consider obesity measures, metabolic profiles and dietary fatty acids simultaneously to better comprehend the condition (s).

Adult↗
PubMed2006

Dynamics of lithium ions in bismuthate glasses: influence of strontium ions.

The influence of strontium ions on the relaxation dynamics of lithium ions in bismuthate glasses has been investigated in the frequency range of 10 Hz to 2 MHz. We have observed that the conductivity increases and the activation energy decreases with the increase of SrO content in the glass compositions with fixed Li2O content. We have also observed that the conductivity increases and the activation energy decreases when Sr2+ ions are replaced by Li+ ions, keeping the glass former content fixed. We have shown that the estimated mobile ion concentration is almost independent of temperature and SrO content in the compositions. We have further shown that a fraction of total lithium ions are mobile for all glass compositions. The results have been interpreted on the basis of the modification of the bismuthate network by the addition of SrO, which enhances the mobility of Li ions, without altering the mobile Li+ ion concentration. We have also shown that the conductivity relaxation in these glasses is independent of temperature and composition, and the nonexponential parameter is less than that for the lithium bismuthate glasses without SrO.

Journal Article↗
PubMed2006

Pregnancy outcomes, infant mortality, and arsenic in drinking water in West Bengal, India.

Between 2001 and 2003, the authors studied pregnancy outcomes and infant mortality among 202 married women in West Bengal, India. Reproductive histories were ascertained using structured interviews. Arsenic exposure during each pregnancy, including all water sources used, was assessed; this involved measurements from 409 wells. Odds ratios for spontaneous abortion, stillbirth, neonatal mortality, and infant mortality were estimated with logistic regression based on the method of generalized estimating equations. Exposure to high concentrations of arsenic (> or =200 microg/liter) during pregnancy was associated with a sixfold increased risk of stillbirth after adjustment for potential confounders (odds ratio (OR) = 6.07, 95% confidence interval (CI): 1.54, 24.0; p = 0.01). Arsenic-related skin lesions were found in 12 women who had a substantially increased risk of stillbirth (OR = 13.1, 95% CI: 3.17, 54.0; p = 0.002). The odds ratio for neonatal death was 2.81 (95% CI: 0.73, 10.8). No association was found between arsenic exposure and spontaneous abortion (OR = 1.01, 95% CI: 0.38, 2.70) or overall infant mortality (OR = 1.33, 95% CI: 0.43, 4.04). This study adds to the limited evidence that exposure to high concentrations of arsenic during pregnancy increases the risk of stillbirth. However, there was no indication of the increased rates of spontaneous abortion and overall infant mortality that have been reported in some studies.

Arsenic Poisoning↗
PubMed2006

Prenatal detection of a de novo Yqh-acrocentric translocation.

OBJECTIVES: To identify the extra chromosomal material on 46,XX,21p+ for prenatal diagnosis. DESIGN AND METHODS: Conventional cytogenetic studies using GTG (G bands by trypsin using Giemsa) and CBG (C bands by barium hydroxide using Giemsa) techniques were performed on chromosomes at metaphase obtained from cultured amniocytes and parental blood lymphocytes. Molecular cytogenetic techniques, QF-PCR (quantitative fluorescent polymerase chain reaction), FISH (fluorescent in-situ hybridization), and DA-DAPI (Distamycin A and 4,6-diamino-2-phenylindole) staining, were then used to clarify the extra material present on fetal chromosome 21 p. RESULTS: The extra material on fetal chromosome 21 p has originated from Yqh, most likely at PAR2 (the secondary pseudoautosomal region). The karyotype should be 46,XX,der(21)t(Y;21)(q12;p13)de novo.ish der(21)t(Y;21)(q12;p13) (EST Cdy16c07+). CONCLUSION: This case demonstrates the usefulness of molecular techniques in the investigation of rare chromosomal rearrangements.

Adult↗
PubMed2006

Euler buckling-induced folding and rotation of red blood cells in an optical trap.

We investigate the physics of an optically driven micromotor of biological origin. When a single, live red blood cell (RBC) is placed in an optical trap, the normal biconcave disc shape of the cell is observed to fold into a rod-like shape. If the trapping laser beam is circularly polarized, the folded RBC rotates. A model based on geometric considerations, using the concept of buckling instabilities, captures the folding phenomenon; the rotation of the cell is rationalized using the Poincaré sphere. Our model predicts that (i) at a critical power of the trapping laser beam the RBC shape undergoes large fluctuations, and (ii) the torque that is generated is proportional to the power of the laser beam. These predictions are verified experimentally. We suggest a possible mechanism for the emergence of birefringent properties in the RBC in the folded state.

Animals↗
PubMed2006

Long-term correction of murine glycogen storage disease type Ia by recombinant adeno-associated virus-1-mediated gene transfer.

Glycogen storage disease type Ia (GSD-Ia) is caused by a deficiency in glucose-6-phosphatase-alpha (G6Pase-alpha), a nine-transmembrane domain, endoplasmic reticulum-associated protein expressed primarily in the liver and kidney. Previously, we showed that infusion of an adeno-associated virus (AAV) serotype 2 vector carrying murine G6Pase-alpha (AAV2-G6Pase-alpha) into neonatal GSD-Ia mice failed to sustain their life beyond weaning. We now show that neonatal infusion of GSD-Ia mice with an AAV serotype 1-G6Pase-alpha (AAV1-G6Pase-alpha) or AAV serotype 8-G6Pase-alpha (AAV8-G6Pase-alpha) results in hepatic expression of the G6Pase-alpha transgene and markedly improves the survival of the mice. However, only AAV1-G6Pase-alpha can achieve significant renal transgene expression. A more effective strategy, in which a neonatal AAV1-G6Pase-alpha infusion is followed by a second infusion at age one week, provides sustained expression of a complete, functional, G6Pase-alpha system in both the liver and kidney and corrects the metabolic abnormalities in GSD-Ia mice for the 57 week length of the study. This effective use of gene therapy to correct metabolic imbalances and disease progression in GSD-Ia mice holds promise for the future of gene therapy in humans.

Animals↗
PubMed2006

Generation and characterization of a novel hematopoietic progenitor cell line with DC differentiation potential.

Studies of hematopoietic stem cell (HSC)-derived dendritic cells (DCs) are often limited by the rarity of HSC. To facilitate the study of DCs, we have generated a novel cell line (CR1) by retroviral Notch(IC) gene transfer into Sca1(+)ckit(+)lin- HSC. CR1 cells proliferated in vitro in the presence of recombinant interleukin-3. They maintained an immature progenitor cell phenotype and an intact karyotype. In the presence of granulocyte-macrophage colony-stimulating factor or Flt3L, CR1 cells differentiated into myeloid and plasmacytoid DCs, respectively. Functionally, CR1 cells were comparable to primary bone-marrow-derived DCs with respect to Toll-like-receptor-mediated maturation, cytokine release and capacity to induce effective antitumor immunity. CR1 cells thus provide an elegant new cellular tool to study DC development, function and preclinical DC-based immunotherapies.

Cell Differentiation↗
PubMed2006

Automated sensitivity analysis of stiff biochemical systems using a fourth-order adaptive step size Rosenbrock integration method.

Sensitivity analysis is one of the most effective approaches for studying mathematical models of biochemical systems. A stiff Rosenbrock integrator has been developed for sensitivity analysis using a direct sensitivity approach. Automated sparse Jacobian and Hessian calculations of the coupled system (the original model equations and the sensitivity equations) have been implemented in the freely available software package CellSim. The accuracy and efficiency of the integrator are tested extensively on the complex mitogen-activated protein kinase (MAPK) pathway model of Bhalla and Iyengar. Both time-dependent concentration and parameter-based sensitivity coefficients are measured using several integration schemes. The method is shown to perform sensitivity analysis in a manner that is cost effective with moderate accuracy. The error control strategy between the decoupled direct method and the Rosenbrock with direct method is discussed and their computational accuracies are compared. The method is used to analyse the positive feedback loop within the MAPK signal transduction pathway.

Algorithms↗
PubMed2006

Anti-phospholipid antibodies as a cause of recurrent pregnancy loss: a study in Calcutta, India.

This prospective, observational study was carried out in a teaching hospital in Calcutta, India. The aim of the study was to evaluate the prevalence of anti-phospholipid syndrome (APS) among women with recurrent miscarriages/late pregnancy loss when no other apparent causes were identified, in the study population. The women were put through a variety of investigations to determine the cause of miscarriage/pregnancy loss. Only those women who had a normal result for all the investigation went for the anti-phospholipid antibodies (APLA) test. The expelled products of conception/placenta were also sent for histopathological confirmation. A total of 445 women were studied over a 4-year period. A total of 155 women were offered a screening for APLA antibodies. Out of them, 43 women (27.7%) tested positive for APLA. Histopathological evidence was present in all the specimens. Interestingly, one woman had histopathological evidence of thrombosis, but her blood tests for the antibody were negative.

Abortion, Habitual↗
PubMed2006

Enterotoxigenicity of mature 45-kilodalton and processed 35-kilodalton forms of hemagglutinin protease purified from a cholera toxin gene-negative Vibrio cholerae non-O1, non-O139 strain.

Cholera toxin gene-negative Vibrio cholerae non-O1, non-O139 strain PL-21 is the etiologic agent of cholera-like syndrome. Hemagglutinin protease (HAP) is one of the major secretory proteins of PL-21. The mature 45-kDa and processed 35-kDa forms of HAP were purified in the presence and absence of EDTA from culture supernatants of PL-21. Enterotoxigenicities of both forms of HAP were tested in rabbit ileal loop (RIL), Ussing chamber, and tissue culture assays. The 35-kDa HAP showed hemorrhagic fluid response in a dose-dependent manner in the RIL assay. Histopathological examination of 20 microg of purified protease-treated rabbit ileum showed the presence of erythrocytes and neutrophils in the upper part of the villous lamina propria. Treatment with 40 microg of protease resulted in gross damage of the villous epithelium with inflammation, hemorrhage, and necrosis. The 35-kDa form of HAP, when added to the lumenal surface of rat ileum loaded in an Ussing chamber, showed a decrease in the intestinal short-circuit current and a cell rounding effect on HeLa cells. The mature 45-kDa form of HAP showed an increase in intestinal short-circuit current in an Ussing chamber and a cell distending effect on HeLa cells. These results show that HAP may play a role in the pathogenesis of PL-21.

Animals↗
PubMed2005

Relaxation dynamics in AgI-doped silver vanadate superionic glasses.

Relaxation dynamics of Ag+ ions in several series of AgI-Ag2O-V2O5 superionic glasses has been studied in the frequency range from 10 Hz to 2 MHz and in the temperature range from 93 to 323 K. The composition dependence of the dc conductivity and the activation energy of these glasses has been compared with those of AgI-doped silver phosphate and borate glasses. The frequency-dependent electrical data have been analyzed in the framework of conductivity formalism. We have obtained the mobile ion concentration and the power-law exponent from the analysis of the conductivity spectra. We have observed that the concentration of Ag+ ions is independent of temperature and the conductivity is primarily determined by the mobility. A fraction of the Ag+ ions in the glass compositions are involved in the dynamic process. We have also shown that the power-law exponent is independent of temperature. The results are also supported by the temperature and composition independence of the scaling of the conductivity spectra.

Journal Article↗
PubMed2005

Different approaches of gene therapy used in prostate cancer.

Prostate cancer is the second leading malignancy next to lung cancer among American males. Estimated number of new cases of prostate cancer by the year 2004 will be 230,110 and number of deaths due to this disease will be 29,900 (American Cancer Society, Surveillance Research, 2004). Major progress have been made in gene therapy due to significant advancement of biology including specialized fields like Molecular Biology, Cell Biology, Immunology and Molecular Virology which includes development of viral and non-viral vectors and delivery system, of which targeted delivery of suicide genes using tissue specific promoter-enhancer, combined therapy, gene replacement therapy are most notable. In this report, we will review about various aspects of gene therapy including most recent discoveries in this field.

Animals↗
PubMed2005

Zero-bias anomaly and kondo-assisted quasiballistic 2D transport.

Nonequilibrium transport measurements in mesoscopic quasiballistic 2D electron systems show an enhancement in the differential conductance around the Fermi energy. At very low temperatures, such a zero-bias anomaly splits, leading to a suppression of linear transport at low energies. We also observed a scaling of the nonequilibrium characteristics at low energies which resembles electron scattering by two-state systems, addressed in the framework of two-channel Kondo model. Detailed sample-to-sample reproducibility indicates an intrinsic phenomenon in unconfined 2D systems in the low electron-density regime.

Journal Article↗
PubMed2005

Dynamics of lithium ions in calcium bismuthate glasses.

Ion transport in Li(2)O-CaO-Bi(2)O(3) glasses has been studied in the frequency range from 10 Hz to 2 MHz and in the temperature range from 293 to 543 K. The variation of the dc conductivity and the activation energy of these glasses with composition have been compared with those of binary lithium bismuthate glasses. It has been observed that the introduction of CaO in small amount does not effect the dc conductivity and the corresponding activation energy, but the larger amount of CaO changes them to some extent. The frequency-dependent conductivity has been studied using both conductivity and modulus formalisms. The values of the nonexponential parameter and frequency exponent are found to differ for the Li(2)O-CaO-Bi(2)O(3) glasses from those for the binary Li(2)O-Bi(2)O(3) glasses. The concentration of mobile Li(+) ions does not change appreciably with the change in the Li(2)O as well as CaO content in the compositions. The increasing amount of CaO in the glass compositions for fixed Li(2)O content points out that CaO dilates the glass network, enhancing the migration of Li(+) ions.

Journal Article↗
PubMed2005

Comparative study of oestrogenic properties of eight phytoestrogens in MCF7 human breast cancer cells.

Previous studies have compared the oestrogenic properties of phytoestrogens in a wide variety of disparate assays. Since not all phytoestrogens have been tested in each assay, this makes inter-study comparisons and ranking oestrogenic potency difficult. In this report, we have compared the oestrogen agonist and antagonist activity of eight phytoestrogens (genistein, daidzein, equol, miroestrol, deoxymiroestrol, 8-prenylnaringenin, coumestrol and resveratrol) in a range of assays all based within the same receptor and cellular context of the MCF7 human breast cancer cell line. The relative binding of each phytoestrogen to oestrogen receptor (ER) of MCF7 cytosol was calculated from the molar excess needed for 50% inhibition of 3H]oestradiol binding (IC50), and was in the order coumestrol (35x)/8-prenylnaringenin (45x)/deoxymiroestrol (50x)>miroestrol (260x)>genistein (1000x)>equol (4000x)>daidzein (not achieved: 40% inhibition at 10(4)-fold molar excess)>resveratrol (not achieved: 10% inhibition at 10(5)-fold molar excess). For cell-based assays, the rank order of potency (estimated in terms of the concentration needed to achieve a response equivalent to 50% of that found with 17beta-oestradiol (IC50)) remained very similar for all the assays whether measuring ligand ability to induce a stably transfected oestrogen-responsive ERE-CAT reporter gene, cell growth in terms of proliferation rate after 7 days or cell growth in terms of saturation density after 14 days. The IC50 values for these three assays in order were for 17beta-oestradiol (1 x 10(-11)M, 1 x 10(-11)M, 2 x 10(-11)M), and in rank order of potency for the phytoestrogens, deoxymiroestrol (1 x 10(-10)M, 3 x 10(-11)M, 2 x 10(-11)M)>miroestrol (3 x 10(-10)M, 2 x 10(-10)M, 8 x 10(-11)M)>8-prenylnaringenin (1 x 10(-9)M, 3 x 10(-10)M, 3 x 10(-10)M)>coumestrol (3 x 10(-8)M, 2 x 10(-8)M, 3 x 10(-8)M)>genistein (4 x 10(-8)M, 2 x 10(-8)M, 1 x 10(-8)M)/equol (1 x 10(-7)M, 3 x 10(-8)M, 2 x 10(-8)M)>daidzein (3 x 10(-7)M, 2 x 10(-7)M, 4 x 10(-8)M)>resveratrol (4 x 10(-6)M, not achieved, not achieved). Despite using the same receptor context of the MCF7 cells, this rank order differed from that determined from receptor binding. The most marked difference was for coumestrol and 8-prenylnaringenin which both displayed a relatively potent ability to displace [3H]oestradiol from cytosolic ER compared with their much lower activity in the cell-based assays. Albeit at varying concentrations, seven of the eight phytoestrogens (all except resveratrol) gave similar maximal responses to that given by 17beta-oestradiol in cell-based assays which makes them full oestrogen agonists. We found no evidence for any oestrogen antagonist action of any of these phytoestrogens at concentrations of up to 10(-6)M on either reporter gene induction or on stimulation of cell growth.

Biological Assay↗