Search PubMed⌕ Search

Biomedical subjects

S Ghosh

Publications and source records attributed to S Ghosh.

At least 577 records · Page 32Linked to original sources
PubMed1995

Comparative pathology of microcystin-LR in cultured hepatocytes, fibroblasts, and renal epithelial cells.

The cyanobacterial toxin microcystin-LR (MCLR) is a potent inhibitor of protein phosphatases 1 and 2A, and is selectively toxic to the liver in vivo and to isolated hepatocytes in vitro. This selectivity is believed to be due to toxin uptake via bile acid carriers. We investigated at the light and ultrastructural levels the effects of high concentrations of MCLR and long incubation times to determine in vitro whether fibroblasts and kidney cells (non-target cells) respond in the same manner as do hepatocytes (target cells) at low concentrations and short incubation times. Cultured rat skin fibroblasts (ATCC 1213) and rat kidney epithelial cells (ATCC 1571) were incubated with with MCLR at 133 microM for 1-24 hr. Lesions in these cells were compared with those in cultured hepatocytes incubated MCLR at 13.3 microM from 1 to 32 min. Lesions in hepatocytes, kidney cells, and fibroblasts were noted at 4 min, 1 hr, and 8 hr, respectively, after initial exposure to MCLR. Lesions in all three cell types progressed and included plasma membrane blebbing, loss of cell-to-cell contact, clumping and rounding of cells, cytoplasmic vacuolization, and redistribution of cytoplasmic organelles. Loss of microvilli, whorling of rough endoplasmic reticulum, dense staining and dilated cristae in mitochondria, and pinching off of membrane blebs were noted only in hepatocytes. Nuclear changes typical of apoptosis were observed only in fibroblasts and kidney cells. Similarities in responses of different cell types to MCLR exposure probably reflect a common biochemical mechanism of action, i.e., inhibition of protein phosphatases 1 and 2A as described by others.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Effects of microcystin-LR on actin and the actin-associated proteins alpha-actinin and talin in hepatocytes.

Microcystin-LR (MCLR) is a commonly encountered blue-green algal hepatotoxin and a known inhibitor of cellular protein phosphatase types 1 and 2A. The toxin causes alterations in, and redistribution of, intermediate filaments, microtubules, and actin microfilaments (MFs) in affected cells. In this study, the effect of MCLR on the sequence of alterations in MFs and actin-associated proteins (AAPs) of isolated hepatocytes was examined in an effort to determine whether morphologic changes induced in MFs by microcystins are a result of prior dislocation of AAPs. We studied the effects of MCLR exposure on alpha-actinin and talin, two AAPs that play a role in the orientation of the MFs. Primary hepatocytes were incubated with 10 microns MCLR for 0-64 min. The distribution of actin, alpha-actinin, and talin were examined using fluorescence microscopy. MCLR induced similar changes in the distribution of actin and the AAPs. Actin filament redistribution was first observed after 12 min of MCLR exposure, and was characterized by detachment of MFs from the cell periphery, followed by condensation at distinct focal points and progressive collapse into the interior of affected cells. Changes in alpha-actinin and talin distribution were first observed after 20 min of toxin exposure. The AAPs appeared to detach from focal contacts on the cytoplasmic surface of the plasma membrane, condense into cytoplasmic aggregates, and ultimately collapse into a juxtanuclear bundle. The results of this study indicate that, in hepatocytes exposed to MCLR, the collapse of actin MFs occurs prior to the dislocation of alpha-actinin and talin. Changes in these actin associated proteins are not likely to account for the initial changes in actin MFs.

Actin Cytoskeleton↗
PubMed1995

Crystallization and preliminary crystallographic data for class I deoxyribose-5-phosphate aldolase from Escherichia coli: an application of reverse screening.

X-ray quality crystals of class I-deoxyribose-5-phosphate aldolase from Escherichia coli have been obtained for the unliganded enzyme and in complex with its substrate, 2-deoxyribose-5-phosphate. The enzyme catalyzes the reversible cleavage of 2-deoxyribose-5-phosphate to acetaldehyde and D-glyceraldehyde-3-phosphate. The unliganded and complex crystals are prismatic long rods and belong to the orthorhombic space group P2(1)2(1)2(1) with cell dimensions a = 183.1 A, b = 61.4 A, c = 49.3 A and a = 179.2 A, b = 60.5, A, c = 49.1 A, respectively. Two molecules in the asymmetric unit are related by a noncrystallographic 2-fold axis. The crystals are stable in the X-ray beam and diffract to at least 2.6 A. A new method, reverse screening, designed to minimize protein utilization during the screening process was used to determine supersaturation and crystallization conditions.

Aldehyde-Lyases↗
PubMed1995

Some aspects of the causes of enhanced immune response of in vitro frozen ascites fibrosarcoma tumor cells in mice.

Estimation of 3 M KCl-extracted ascites fibrosarcoma (AFS) tumor cell membrane peripheral proteins in native and frozen tumor cells showed approximately a three-, four-, and fivefold increase per 1 x 10(6) cells of single-, three-, and programmed three-cycle frozen AFS tumor cells, respectively, compared to the same number of native cells, indicating an increase in surface membrane protein concentration with freezing. The 10% gel (homogeneous) electrophoretic (SDS-PAGE) study of 3 M KCl-extracted native and frozen cell membrane proteins showed (i) membrane proteins of native cells resolve into many more components compared to those of any frozen membranes, i.e., single, three, and programmed three cycle, the components decreasing in that order; (ii) the concentration of larger-molecular-weight protein fractions (> or = 75 kDa) decreases while those of smaller fractions (14 to 24 kDa) increase in frozen cells, with the maximum being in the programmed three-cycle frozen group. In contrast, the native cell membrane is rich in higher-molecular-weight proteins (> or = 75 kDa) with concentrations slowly decreasing toward lower-molecular weight fractions. Thus, the probable reasons for increased immune response of animals immunized with frozen AFS tumor cells are (i) absolute increase in cell surface protein concentrations as given by 3 M KCl extraction of cell membrane peripheral protein estimation in AFS tumor cells postfreeze; (ii) cell-surface protein pattern which is heterogeneous before freezing becomes relatively more homogeneous following freezing of AFS tumor cells; and (iii) depolymerization and breaking of higher-molecular-weight components which increase the concentration of terminal-sequence antigenic determinants and increase accessibility of determinant grouping by removing steric hindrance following freezing.

Animals↗
PubMed1995

Electronic quality of life questionnaires: a comparison of pen-based electronic questionnaires with conventional paper in a gastrointestinal study.

The use of pen-based electronic questionnaires and conventional paper questionnaires was compared in a randomized crossover study. Forty-six patients, aged 17-81 years, suffering from gastro-intestinal disorders, initially filled in a paper quality of life questionnaire for familiarization purposes, then on two subsequent visits completed electronic and paper questionnaires in randomized order. At the last visit they completed a preference survey. The results showed a high degree of acceptability of the electronic questionnaire, with 57% of patient preferring electronic and 13% preferring paper, while the remaining 30% expressed no preference. Neither age, gender nor familiarity with technology showed any marked association with patients' preferences. All patients found both paper and electronic questionnaires easy to use. Data were more complete on the electronic questionnaire (100%) than on the paper (99.1%). Data handling procedures were greatly simplified. These results show that major benefits in completeness of data, speed of data flow, and data handling workload can be obtained from the use of pen-based electronic questionnaires.

Adolescent↗
PubMed1995

Purification, properties, and immunological characterization of GalT-3 (UDP-galactose: GM2 ganglioside, beta 1-3 galactosyltransferase) from embryonic chicken brain.

A beta 1-3 galactosyltransferase (GalT-3; UDP-Gal; GM2 beta 1-3 galactosyltransferase) was purified over 5100-fold from 19-day-old embryonic chicken brain homogenate employing detergent solubilization, alpha-lactalbumin Sepharose, Q-Sepharose, UDP-hexanolamine Sepharose, and GalNAc beta 1-4Gal beta-Synsorb column chromatography. The purified enzyme was resolved into two bands on reducing gels with apparent molecular weights of 62 kDa and 65 kDa, respectively. GalT-3 activity was also localized in the same regions by activity gel analysis and sucrose-density gradient centrifugation of a detergent-solubilized extract of 19-day-old embryonic chicken brain. Purified GalT-3 exhibited apparent Kms of 33 microM, and 14.4 mM with respect to the substrates GM2, UDP-galactose, and MnCl2, respectively. Substrate specificity studies with the purified enzyme and a variety of glycosphingolipids, glycoproteins, and synthetic substrates revealed that the enzyme was highly specific only for the glycosphingolipid acceptors, GM2 and GgOse3Cer (asialo-GM2). Ovine-asialo-agalacto submaxillary mucin inhibited the transfer of galactose to GM2 but did not act as an acceptor in the range of concentrations tested. Polyclonal antibodies raised against purified GalT-3 inhibited GalT-3 activity in vitro and Western-immunoblot analysis of purified GalT-3 showed immunopositive bands at 62 and 65 kDa.

Animals↗
PubMed1995

Randomized, controlled trial of antioxidant vitamins and cardioprotective diet on hyperlipidemia, oxidative stress, and development of experimental atherosclerosis: the diet and antioxidant trial on atherosclerosis (DATA).

The effects of administration of guava and papaya fruit (100 g/day), vegetables, and mustard oil (5 g/day) (group A); antioxidant vitamins C (50 mg/day) and E (30 mg/day), plus betacarotene (10 mg/day) (group B); a high-fat (5-10 g/day) (group C); or a low-fat (4-5 g/day) diet (group D) were compared over 24 diet weeks in a randomized fashion, while all groups of rabbits (five in each of four groups) received a hydrogenated fat diet (5-10 g/day) for a period of 36 weeks. After 12 weeks on the high-fat diet, each group of rabbits had an increase in blood lipoproteins. The fruit and vegetable-enriched prudent diet (group A) caused a significant decline in blood lipids at 24 and 36 weeks, whereas the lipid levels increased significantly in groups C and D. Group A also had a significant rise in vitamin E (2.1 Umol/l), C (10.5 Umol/l), A (0.66 Umol/l), and carotene (0.08 Umol/l) and a decrease in lipid peroxides (0.34 nmol/ml at 36 weeks, whereas the levels were unchanged in groups C and D. Group B rabbits had a significant and greater increase than group A in plasma vitamins E, C, A, and carotene; a rise in HDL cholesterol; and a greater decrease in lipid peroxides after 24 and 36 weeks of treatment. After stimulation of lipid peroxidation in all rabbits, 3 of 5 group C and 2 of 5 group D rabbits died due to coronary thrombosis, whereas in groups A and B there were no deaths, indicating that antioxidant therapy can provide protection against lipid peroxidation and free radical generation. Aortic lipids and sudanophilia, indicating atherosclerosis, were significantly higher in groups C and D than in groups A and B. Fatty streaks and atheromatous and fibrous plaques were noted in all the rabbits in groups C and D. Intimal fibrosis and medial degeneration were also present in the group C rabbits. While group A (36.4 +/- 4.4 microns) and group B (37.1 +/- 4.2 microns) rabbits had minimal coronary artery plaque sizes, group C (75.4 +/- 10.6 microns) and group D rabbits (69.5 +/- 6.2 microns) had significantly greater plaque sizes. Aortic plaque sizes were also greater in groups C and D than in groups A and B. It is possible that combined therapy with antioxidant vitamins C, E, and carotene, and a diet rich in antioxidants, could independently inhibit free radical generation and the development of atherosclerosis.

Animals↗
PubMed1995

An anthropometric survey of Indian schoolchildren aged 3-5 years.

Kindergartens of age group 3-5 years, a distinct and small subgroup of Indian schoolchildren, need special emphasis on human factors. The paper presents the results of an anthropometric survey conducted on schoolchildren. These data, previously lacking in India, can be of benefit for the designers of kindergartens. A set of 81 different body dimensions was taken from a sample of 198 children of age group 3-4 years and 4.1-5 years. Simple anthropometric techniques were used to collect the data. Statistical analyses of the data have been presented in a tabular form for designers as well as for non-technical users. It is emphasized that such data have to be developed at the national level, including every ethnic group, or on a regional basis. Designers, manufacturers and importers of goods should have access to these data.

Journal Article↗
PubMed1995

Higher environmental temperature-induced increase of body temperature: involvement of central opioidergic-GABAergic interaction.

Exposure (2 h) of male albino rats to higher environmental temperature (HET, 40 degrees C) significantly increased the body temperature (BT). Administration of bicuculline (1 mg/kg, i.p.), physostigmine (0.2 mg/kg, i.p.), or their combination significantly raised the BT of normal rats (kept at 28 degrees C) or of HET-exposed rats. Atropine (5 mg/kg, i.p.) abolished the hyperthermic effect of bicuculline in normal and HET-exposed rats. The BT of normal and HET-exposed rat was increased with morphine (1 mg/kg, i.p.) and was reduced with naloxone (1 mg/kg, i.p.). Bicuculline or physostigmine-induced rise in BT of HET-exposed rats was potentiated following cotreatment of physostigmine with morphine. Atropine-induced hypothermia was abolished due to the cotreatment of atropine with morphine with physostigmine but was attenuated with atropine. In normal rats (kept at 28 degrees C), only atropine attenuated (morphine + bicuculline)-induced hyperthermia. L-Dopa + carbidopa or haloperidol did not significantly affect the BT of rats under similar conditions. These results suggest that short-term (2 h) exposure to HET activates the opioidergic neuron, which activates cholinergic activity through the inhibition of GABAergic system and, thus, enhances the BT.

Animals↗
PubMed1995

Protective effects of lazaroid U74389F (16-desmethyl tirilazad) on endrin-induced lipid peroxidation and DNA damage in brain and liver and regional distribution of catalase activity in rat brain.

Endrin, a poly-halogenated cyclic hydrocarbon, induces hepatic lipid peroxidation, modulates calcium homeostasis, decreases membrane fluidity, and increases nuclear DNA damage. Little information is available on the neurotoxicity of endrin. The effects of endrin on lipid peroxidation, DNA damage, and regional distribution of catalase activity were assessed in rat brain and liver 24 h following an acute oral dose of 4.5 mg endrin/kg. Lipid peroxidation associated with whole brain mitochondria increased 2.4-fold, whereas microsomal lipid peroxidation increased 2.8-fold following endrin administration. Lipid peroxidation also increased 2.0-fold both in hepatic mitochondria and microsomes. Catalase activity decreased 24% in the hypothalamus, 23% in the cortex, 38% in the cerebellum, and 11% in the brain stem in response to endrin. A 4.3-fold increase in brain nuclear DNA-single strand breaks (SSB) was observed in endrin-treated rats. Pretreatment of rats intraperitoneally with the lazaroid U74389F (16-desmethyl tirilazad) (10 mg/kg in two doses) attenuated the biochemical consequences of endrin-induced oxidative stress. The administration of U74389F in citrate buffer (pH 3.8) provided better protection than administering the lazaroid in corn oil, decreasing endrin-induced lipid peroxidation by 50-80% and DNA-SSB by approximately 72% in liver and 85% in brain, while ameliorating the suppressed catalase activity. The data suggest an involvement of an oxidative stress in the neurotoxicity and hepatotoxicity induced by endrin, which can be attenuated by the lazaroid U74389F.

Animals↗
PubMed1995

Alpha 2-adrenergic receptor gene polymorphism and hypertension in blacks.

alpha 2-Adrenergic receptors are found on presynaptic neurons of the central and peripheral nervous systems, on blood vessels, on platelets, on adipocytes, and in the kidney and pancreas. Activation of these ubiquitous adrenoreceptors results in decreased neuronal norepinephrine release, vasodilation, a fall in blood pressure, platelet aggregation, increased sodium excretion, and decreased insulin release. We hypothesized that defects in alpha 2-adrenergic receptors, or postreceptor defects, could explain the increased prevalence of hypertension in blacks. To test our hypothesis, we first determined whether or not a polymorphism of the alpha 2-adrenergic receptor gene was associated with pathologic elevations in blood pressure in American blacks. Dra-I identified a restriction fragment-length polymorphism (RFLP) of 6.3 and 6.7 kb of the alpha 2-adrenergic receptor gene on chromosome 10 in humans. Of 227 patients studied, 13/107 hypertensive subjects were homozygous for the 6.3-kb allele, whereas only 3/120 normotensive volunteers were homozygotes (P = .008). When analyzed by race, 13/82 black hypertensive subjects were homozygous for the 6.3-kb allele, whereas only 2/59 normotensive blacks were homozygous for the 6.3-kb alleles (P = .02). However, only 1/61 white normotensive and 0/25 white hypertensive subjects were homozygous for the 6.3-kb allele (P = 1.00). Ethnic variation among blacks may explain our findings. Alternatively, a genetic polymorphism in, or near, the alpha 2-adrenergic receptor on chromosome 10 can contribute to the development of hypertension in blacks.

Alleles↗
PubMed1995

Immortalization of cat iris sphincter smooth muscle cells by SV40 virus: growth, morphological, biochemical and pharmacological characteristics.

The purpose of this study was to establish immortalized cell cultures of cat iris sphincter smooth muscle cells for a model investigating ocular receptors and their signal transduction pathways. Cultured cat iris sphincter muscle cells were immortalized by viral transformation with SV40 virus and the morphological and immunocytochemical properties of the normal and immortalized cells were investigated. The transformed cell clone, SV-CISM-2, was further characterized biochemically and pharmacologically. The normal muscle cells showed characteristics of smooth muscle cells, as judged by their growth and the presence of smooth muscle alpha-actin and desmin. After seven passages the normal cells ceased to proliferate. In contrast, the immortalized cells retained their proliferative ability for more than 220 population doublings over 55 passages. The transformation phenotype in these cells was confirmed by their expression of the large T-antigen, the incorporation of viral DNA into cellular DNA, growth in agarose and in low-serum medium, and complete loss of contact inhibition. The immortalized cells expressed smooth muscle alpha-actin, desmin and MLC protein. Biochemical and pharmacological studies on the SV-CISM cells revealed the presence of several functional receptors including muscarinic cholinergic, beta-adrenergic, peptidergic (substance P and endothelin). Platelet-activating factor, and prostaglandin (PG). Muscarinic stimulation of these cells resulted in: (a) a dose-dependent increase in the release of arachidonic acid (AA) and (PGs) and enhancement in the production of inositol trisphosphate (IP3); and (b) a substantial increase in MLC phosphorylation (118%), an indicator of smooth muscle contractility. The stimulatory effects of carbachol on these responses were completely blocked by atropine, a muscarinic receptor antagonist. This study constitutes the first successful immortalization of iris sphincter smooth muscle cells. The SV-CISM-2 cells can serve as an important model system for investigations on the biochemical and pharmacological properties of receptors and their signal transduction pathways in smooth muscle. The advantage of these cells over normal iris sphincter cells is that they can be propagated over many generations without alterations in their morphological, biochemical and physiological characteristics.

Animals↗
PubMed1995

Epidemiology of Vibrio cholerae O139 with special reference to intrafamilial transmission in Calcutta.

A total of 27 families of hospitalised patients (index case families) suffering from acute watery diarrhoea caused by Vibrio cholerae O139, and 14 neighbourhood families were bacteriologically screened for 4 consecutive days to determine the extent of V. cholerae O139 infection amongst healthy contacts and other suspected vehicles of transmission at the intrafamilial level. V. cholerae O139 was isolated from faeces of 14.6% of healthy contacts in index case families as compared to none in neighbourhood families (P = 0.002). The organism could be recovered from 3.7% of handwashings of contacts of index cases and also from stored drinking water (8.0%), open well water (28.6%), flies (3.8%) and pond water (25.0%) used by the index case families and none from neighbourhood families. The large number of asymptomatic infected persons indicate an epidemiological similarity to that of eltor cholera. The organisms may be carried on hands and may act as a potential source of infection to other inmates through contamination of stored drinking water, open wells etc. The results will be useful in formulating strategies for intervention of transmission of V. cholerae O139 at the community level.

Cholera↗
PubMed1995

Epidemiological study of coronary artery disease and its risk factors in an elderly urban population of north India.

OBJECTIVE: In view of the rapid increase in the prevalence of coronary artery disease (CAD) in developing countries, our aim was to determine the prevalence of CAD and its risk factors and lifestyle factors in an elderly population from north India. METHODS: A random sample of 595 elderly subjects between 50 to 84 years of age was obtained from the urban population of Moradabad. The response rate was 90.1%. The survey methods included a questionnaire containing information on 7-day food intake, other lifestyle factors, Rose questionnaire for diagnosis of angina pectoris, a standard 12-lead electrocardiogram, blood pressure measurements and blood examination. RESULTS: The total prevalence of CAD based on clinical history and electrocardiogram was 121/1000 (95% CI 72 to 165). The prevalence rate was slightly higher in males (130/1000) than in females (110/1000). The prevalence of CAD based on the Rose questionnaire was 57/1000 and based on electrocardiogram in 561 asymptomatic subjects was 67/1000. CAD was significantly higher in the elderly (65 to 84 years) group than in the middle-aged (50 to 64 years) group (168 vs. 97 per 1000), respectively. While the prevalence of hypertension was significantly higher in the elderly than middle-aged group respectively (214 vs. 168 per 1000), the prevalence of central obesity was significantly higher in the middle-aged than elderly group (674 vs. 632 per 1000). Other risk factors including smoking were comparable in the two subgroups. Prevalence of major risk factors and central obesity were significantly higher among patients with CAD than in the rest of the subjects. Prevalence of CAD was significantly higher in the middle and higher socio-economic groups compared to the lower income group. These higher income groups were also eating significantly higher amounts of visible fat and had a higher prevalence of physical inactivity (93.3%) compared to the lower income group. CONCLUSIONS: CAD and its risk factors such as hypertension, hypercholesterolemia, diabetes and central obesity are of sufficient magnitude in the elderly population of India to be a major public health problem. The findings also indicate that CAD is more commonly associated with middle and higher socio-economic status which may be due to greater consumption of dietary fat and more sedentariness compared to lower socioeconomic groups.

Aged↗
PubMed1995

Pharmacokinetics of analgesics, sedatives and anaesthetic agents during cardiopulmonary bypass.

CPB produces changes in the blood-gas partition coefficient dependent on the prime used and temperature. Fortunately, the overall effect for hypothermic CPB and a crystalloid prime is only +2%. A volatile agent started during hypothermic CPB takes longer to equilibrate and agents already in use need to re-equilibrate, potentially changing the depth of anaesthesia, until equilibration is complete. As these agents are metabolized to a small degree and washout is fast, the duration of action is not prolonged after CPB.

Analgesics, Opioid↗