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Biomedical subjects

P Bhattacharya

Publications and source records attributed to P Bhattacharya.

At least 19 recordsLinked to original sources
PubMed2003

Direct measurement of the photoelectric response time of bacteriorhodopsin via electro-optic sampling.

The photovoltaic signal associated with the primary photochemical event in an oriented bacteriorhodopsin film is measured by directly probing the electric field in the bacteriorhodopsin film using an ultrafast electro-optic sampling technique. The inherent response time is limited only by the laser pulse width of 500 fs, and permits a measurement of the photovoltage with a bandwidth of better than 350 GHz. All previous published studies have been carried out with bandwidths of 50 GHz or lower. We observe a charge buildup with an exponential formation time of 1.68 +/- 0.05 ps and an initial decay time of 31.7 ps. Deconvolution with a 500-fs Gaussian excitation pulse reduces the exponential formation time to 1.61 +/- 0.04 ps. The photovoltaic signal continues to rise for 4.5 ps after excitation, and the voltage profile corresponds well with the population dynamics of the K state. The origin of the fast photovoltage is assigned to the partial isomerization of the chromophore and the coupled motion of the Arg-82 residue during the primary event.

Bacteriorhodopsins↗
PubMed2002

Oncogenic human papillomavirus (HPV) infection and uterine cervical cancer: a screening strategy in the perspective of rural India.

The predominance of cervical cancer in India can mostly be attributed to the lack of early screening. The objective of the present study has been, therefore, to determine a cost-effective oncogenic human papillomavirus (HPV)-based cervical cancer screening plan for rural Indian women. The results showed that in normal women, highest prevalence of HPV 16/18 infection was in the age group < or =23 years and lowest in > or =44 years with an insignificant change in between. HPV 16/18 infection was significantly associated with cervical erosion at age < or =23 years, but not with cytology or visual inspection with acetic acid testing at any age. The low-grade cytological lesions, however, increased only with increase in age. Fourteen per cent of the cervical malignancy was also found to be present in the age group 24-33 years with an 87% HPV infection. Here we proposed a cost-effective screening scheme in which HPV testing must be performed in women (a) < or =23 years with cervical erosion and (b) 24-43 years, as an adjunct to Pap smears (both HPV and cytology were prevalent in this group). For women > or =44 years, HPV testing might not be useful, since abnormal cytology was more prominent over the viral infection. We infer that by not performing HPV test in the group < or =23 years, approximately 76% of the high-risk HPV-infected individuals potentially "at risk" for developing cervical cancer might be missed.

Acetic Acid↗
PubMed2002

Antibiotic sensitivity pattern of the bacteria isolated from nosocomial infections in ICU.

The incidence of nosocomial infections in ICU is 4-5 times greater than in general ward. Critically ill patients are always at higher risk of developing nosocomial infections with resistant strains. This study is an attempt to know the antibiotic sensitivity pattern of the common isolates in ICU. Samples comprising urine, blood, endotracheal secretions and throat swabs were collected from 102 ICU patients of them, 56 patients showed evidence of nosocomial infection (54.9%), from whom 120 different organisms were isolated. Antibiotic sensitivity test was done according to Kirby Bauer method. Klebsiella pneumoniae were the most prevalent isolates from respiratory tract infections followed by Proteus spp, Escherichia coli, Staphylococci spp. and Acinetobacter spp. The gram negative enteric bacilli were uniformly resistant to betalactam antibiotics as well as betalactam-betalactamase inhibitors. Resistance to Ciprofloxacin and Ceftriaxone ranged from 50-100% and 25-83.3% respectively. Staphylococci were 100% resistant to penicillin and tetracycline, 80% to cotrimoxazole, 60% to erythromycin and gentamicin and 40% to amikacin. Acinetobacter spp. were highly resistant to most of the antibacterial agents except gentamicin while Pseudomonas spp. showed 75% resistance to it. The increased prevalence of resistant organisms in ICU probably reflects lack of proper antibiotic policy resulting in prolonged and indiscriminate use of antimicrobial agent.

Bacterial Infections↗
PubMed2001

Observation of phonon bottleneck in quantum dot electronic relaxation.

Time-resolved differential transmission measurements of self-assembled In0.4Ga0.6As quantum dots clearly indicate a phonon bottleneck between the n = 2 and n = 1 electronic levels. The key to this observation is the generation of electrons in dots where there are no holes so that electron-hole scattering does not mask the bottleneck. We use a simple carrier capture model consisting of two capture configurations to explain the bottleneck signal and offer arguments to rule out other possible sources of the signal.

Journal Article↗
PubMed2001

Prominence of symptoms and level of stigma among depressed patients in Calcutta.

A pilot study of 29 patients for research on clinical depression employed the framework of cultural epidemiology to examine illness-related experience, meaning, behaviour with a Bengali version of the explanatory Model Interview Catalogue (EMIC). This report examined patterns of distress and stigma with reference to the most troubling patient-specified symptom. All subjects were psychiatric outpatients in the Institute of Psychiatry, Calcutta, and met Diagnostic and Statistical Manual (DSM)-IV criteria for a major depressive episode. Only 5 patients (17.2%) identified sadness as the most troubling problem, and 48.3% specified pains and other somatic symptoms instead. An internally consistent stigma scale with Cronbach's alpha of .67, comprised 13 items, was used to assess stigma. In addition to the scale score for each subject, the contribution of each item was reported and compared. A suggestive, though not significantly lower value of the stigma score for patients reporting somatic symptoms as most troubling, compared with sadness, was consistent with findings from prior studies showing a positive relationship between the magnitude of depression and stigma. These findings are discussed with reference to their impact on recognition and help seeking among patients, and recognition and management of depression by general practitioner. Culturally distinctive presentations and social contexts of depression and other mental illnesses should be addressed in professional training and public health communications.

Adult↗
PubMed2001

Effect of purified glutaminase from human ascites fluid on experimental tumor bearing mice.

Glutamine is the major respiratory fuel and energy source of the rapidly proliferating tumor cells and that is why glutamine clearance by glutaminase therapy provides an opportunity to fight against the neoplasm. Glutaminase from bacterial source was tried on experimental models but had to be excluded because of its limited efficacy. Search for a better glutaminase continued exploiting the mammalian sources. In the present study, glutaminase purified from human ovarian cancer ascites fluid was used in experimental solid and ascites mice model alone and in combination with Cu-Sulphate and heparin. Cumulative findings indicate that the enzyme alone is quite effective in lowering tumor burden and reducing not only the tumor induced angiogenesis, but also an angiogenic inducer, heparin mediated angiogenesis. However, the presence of Cu with the enzyme, amplified the antineoplastic response by improving anti-angiogenic potential and hematological status of the tumor bearing host. Therefore, Cu-glutaminase combination strengthened the hypothesis that together they may provide a better therapeutic regimen in experimental mice tumor model.

Angiogenesis Inhibitors↗
PubMed2000

Studies on the modeling and simulation of a sequential bienzymatic reaction system immobilized in emulsion liquid membrane.

Experiments have been carried out to study the reaction engineering behavior of the liquid membrane-encapsulated, sequential bienzymatic reaction system, n 2n glucose. A dynamic mathematical model, free from adjustable parameters, has been developed taking into account peri-emulsion mass transfer, intra-emulsion diffusion, membrane-related mass transfer limitations and substrate and product inhibitions. A finite difference-based, user-friendly software has been developed to solve the model equations. Experimental data satisfactorily correlate with the model. While it is understood that study of sequential bienzymatic reaction system immobilized in emulsion liquid is essential for their industrial exploitation, reaction engineering behavior of such a system in presence of both substrate and product inhibitions has not yet been reported in the literature. Therefore, the model predictions of the present investigations are expected to pave the way for scale-up and design of industrial bioreactors in this field.

Journal Article↗
PubMed2000

Effects of intraseptal zolpidem and chlordiazepoxide on spatial working memory and high-affinity choline uptake in the hippocampus.

Injection of GABA(A)/benzodiazepine receptor ligands into the medial septum (MS) alters the activity of cholinergic neurons that innervate the hippocampus and can produce bidirectional modulation of spatial memory. Recent evidence suggests that two subtypes of the GABA(A) receptor are differentially localized to either GABAergic (alpha(1)/beta(2)/gamma(2)) or cholinergic (alpha(3)/beta(3)/gamma(2)) neurons within the MS. The present studies characterized the dose-related behavioral and neurochemical effects of intraseptal infusions of two benzodiazepine (BDZ) agonists that appear to exhibit different profiles of pharmacological specificity for these receptor subtypes. Male Sprague-Dawley rats were cannulated and then artificial CSF, chlordiazepoxide (CDP: 8 or 12 microg), or zolpidem (4, 8, or 12 microg) was injected into the MS. Spatial working memory was assessed in a delay radial-arm maze task and the activity of cholinergic neurons in the MS was evaluated by high-affinity choline uptake (HA-ChU) in the hippocampus. Intraseptal injection of either CDP or zolpidem produced dose-related impairments in spatial working memory and decreases in hippocampal HAChU. Both BDZ agonists were found to produce retrograde memory deficits and a decrease in HAChU following the highest dose tested (12 microg). However, intraseptal injection of 8 microg of zolpidem produced a behavioral deficit comparable to the high dose of CDP, but did not alter HAChU within the HPC. Although the cholinergic component of the septohippocampal pathway has been shown to be important in modulating hippocampal physiology and spatial memory processes, data from the present experiments suggest that the GABAergic component may also play an important role in the behavioral functions of the septohippocampal pathway.

Animals↗
PubMed2000

Localization of phosphate dependent glutaminase in ascites fluid of ovarian cancer patient.

Phosphate dependent glutaminase was purified from ascites fluid of ovarian cancer patients. The purified enzyme showed a final specific activity of 110 unit / mg protein with 72 fold purification and 21% yield. Purified enzyme gives one dark band of Mr approximately 65.5 KD and two light bands of Mr approximately 47.5 KD and approximately 45 KD respectively on 10% SDS-PAGE. One major immunoreactive band was found in trans-immunoblot analysis using antibodies against rat kidney and ascites fluid glutaminase raised in rabbit and mice respectively. Phosphate dependent glutaminase enzyme purified from mitochondria of malignant and non malignant ovarian tissue also showed bands of same molecular weight on 10% SDS-PAGE and gave same immunoreactive bands in trans-immunoblot like the purified glutaminase from ascites fluid. This result was confirmed by using the specific activity stain for glutaminase, which indicates that same enzyme activity is probably due to leakage of the same enzyme from malignant tissue into the ascites fluid. The purified enzyme from human peritoneal fluid showed a high specificity toward glutamine, therefore is a true glutaminase. Moreover, ascites fluid taken from patients of different age group with different stages of ovarian carcinoma revealed the presence of same glutaminase on 10% SDS-PAGE, and exhibited immunoreaction on ELISA, trans-immunoblot and dot immunoblot analysis.

Adult↗
PubMed2000

A general survey of glutamine level in different tissues of murine solid tumor bearing mice before and after therapy with purified glutaminase.

Distribution of glutamine level in different tissues of tumor bearing mice such as brain, liver, kidney, spleen, large and small intestine and the tumor itself were studied in three solid tumor models, viz, Ehrlich ascites carcinoma, Sarcoma-180 and methylcholanthrene induced carcinoma. Tumor bearing mice were subjected to therapy for 7 days with the glutaminase purified from malignant S-180 cell. The results exhibit a significant decrease in tumor burden after enzyme therapy. Host tissue glutamine levels were significantly elevated in tumor bearing untreated mice in comparison to the normal ones, while significant lower values were obtained after enzyme therapy. It therefore appears that elevated levels of glutamine in host tissue are associated with the tumor burden.

Animals↗
PubMed2000

Neovascularisation offers a new perspective to glutamine related therapy.

Angiogenesis or the generation of new blood vessel, is an important factor in the growth of a solid tumor. Hence, it becomes a necessary parameter of any kind of therapeutic study. Glutamine is an essential nutrient of tumor tissue and glutamine related therapy involves clearance of circulatory glutamine by glutaminase. Therefore, using different murine solid tumor models, the present study was undertaken to find out whether the S-180 cell glutaminase has any effect on angiogenesis of solid tumor, or not. Result indicates that the purified S-180 cell glutaminase reduces tumor volume and restrict the generation of neo blood vessels. Therefore, it can be concluded that this enzyme may be an effective device against the cancer metastasis.

Angiogenesis Inhibitors↗
PubMed1999

Angiogenesis a putative new approach in glutamine related therapy.

Angiogenesis or the generation of new blood vessels, is an important factor regarding the growth of a tumor. Hence, it becomes a necessary parameter of any kind in therapeutic studies. Glutamine is an essential nutrient of tumor tissue and glutamine related therapy involves clearance of circulatory glutamine by glutaminase. So, whether this enzyme has any effect on angiogenesis of a tumor or not becomes an obvious question. To address this question, this study has been carried out with different murine tumor models. The results indicate that purified glutaminase reduces tumor volume as well as restricts the generation of new blood vessels. Glutaminase is effective in the case of solid as well as ascites tumor models. In the case of induced cancer, the host exhibits delayed onset of neoplasia following enzyme treatment and tumor host interactions determine the intensity of the neovascularisation process. Therefore, it can be concluded that this enzyme might be an effective agent against cancer metastasis.

Animals↗
PubMed1999

Risk assessment of cardiovascular diseases among bank employees--a biochemical approach.

In different epidemiological studies, an association between sedentary life style and incidence of cardiovascular diseases has been demonstrated. This study was carried out among 50 sedentary bank employees working at different nationalized banks within Calcutta City, India and 50 individuals with non-sedentary jobs matched for age group and sex for the control group. Body mass index (BMI), blood pressure (BP), plasma level of glucose, total cholesterol, low density lipoprotein (LDL), very low density lipoprotein (VLDL) and triglycerides (Tgs) were found to be significantly higher whereas high density lipoprotein (HDL) and reduced glutathione were found to be significantly lower among the bank employees as compared with the control subjects. Further, significant alteration in the activity of different enzymes (e.g., glutathione reductase, glutathione S-transferase, glucose 6 phosphate dehydrogenase, catalase and superoxide dismutase) involved in glutathione-mediated antioxidant scavenging systems and increases in lipid peroxidation were also observed in the bank employees. From the study, it appears that the relative risk for cardiovascular disease is increased among bank employees due to the sedentary nature of their jobs.

Adult↗
PubMed1999

Comparative study of beta-adrenoceptor blocking efficacy of two formulations of esmolol in vivo and in vitro.

The objective of the present study was to compare the cardiovascular beta-blocking activity of two different formulations of esmolol. Spontaneously beating guinea-pig isolated atria and the heart rate and blood pressure of anaesthetized cat were employed in the study to compare the beta-blocking efficacy of the two formulations of esmolol using isoprenaline as an agonist. In guinea-pig isolated atria the standard esmolol formulation (Brevibloc) reduced basal atrial rate more significantly than the indigenously formulated esmolol (test formulation). Both the formulations produced similar parallel rightward shift of cumulative concentration response curves of isoprenaline with closely comparable pA2 values. In anaesthetized cats, only indigenous esmolol formulation significantly decreased basal heart rate. Both the formulations did not modify the basal blood pressure and isoprenaline-induced fall in blood pressure, despite significantly blocking isoprenaline-induced tachycardia. It is suggested that both the formulations produced similar degree of beta-1 adrenoceptor blocking activity.

Adrenergic beta-Antagonists↗
PubMed1999

Isolation and purification of phosphate dependent glutaminase from sarcoma-180 tumor and its antineoplastic effects on murine model system.

High rate of glutamine use is a characteristic of tumor cell both in vivo and in vitro and experimental cancer therapies have developed by depriving tumor cells of glutamine. In several investigations, bacterial glutaminase was found to be a potent therapeutic agent against varieties of tumor, but it showed suppressive effects on haematopoietic systems and inhibitory effects on normal lymphocytic blastogenesis. No antineoplastic study has nevertheless been undertaken with glutaminase enzyme purified from mammalian source. In the present study we report the purification of glutaminase enzyme from mitochondria of highly malignant S-180 cell using ion exchange chromatography and affinity column chromatography of glutamine. Purified enzyme is a kidney type phosphate dependent glutaminase with Mr 64 KD. Effect of enzyme therapy has been investigated in transplantable as well as induced tumor model in both ascites and solid form. It has been observed that the enzyme at the total dose of 10 unit/mouse successfully inhibited the tumor burden both in ascitic and solid tumor and subsequently increases the host's life span. There was no significant toxic effect on the peripheral blood cells.

Animals↗
PubMed1999

Evidence for integration of IS1 and IS10 in recombinant plasmid containing rearrangement hot-spot(rhs) common-shared block(CSB) in Escherichia coli K-12.

The integration of IS1 and IS10 was reported in the recombinant plasmid containing the 3070 bp rearrangement hotspot(rhs) common-shared block(CSB) in Escherichia coli K-12. The integration of IS1 was found to be in rhs(CSB) portion, whereas the integration of IS10 was found to be in both rhs(CSB) and vector portions. The bacterial cells containing the recombinant plasmid grew very slowly. But the integration of IS1 or IS10 in rhs(CSB) portion made the host grow rapidly and overgrew the slow-growing population inheriting the recombinant plasmids without IS-sequences. The sites of integration of IS1 and IS10 were different as was judged from restriction endonuclease mapping. These are rare examples of interchromosomal mobilisation of IS1 and IS10 from host chromosome into plasmid.

DNA Transposable Elements↗
PubMed1999

TSH assay using dried blood samples: a screening method for congenital hypothyroidism.

Capillary blood samples from three hundred healthy, full-term newborn within 48 and 120 hours of delivery, were collected on filter paper for analysis of thyroid-stimulating hormone (TSH). Blood was collected by pricking the heel of the newborn and spotted and dried on filter paper cards. The samples were analysed by immunoradiometric assay (IRMA) to determine the TSH level. Some fifteen percent of a total 1928 deliveries at two hospitals during a period of one year were included in the study. Male:female ratio was 1.1:1. There was no maternal history of thyroid disease. None of the babies had any clinical feature of hypothyroidism. On analysis, TSH level ranged from 0.6-19.3 microU/ml with a mean (SD) of 7.19 (4.21) microU/ml. TSH assay from dried filter paper blood spot is technically possible and is a cost-effective and reliable method for a screening programme. This is the first time in Bangladesh that this method has been successfully carried out.

Bangladesh↗