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S Ghosh

Publications and source records attributed to S Ghosh.

At least 469 records · Page 26Linked to original sources
PubMed1997

Sustained stress and fixed interval performance.

The effects of sustained stress on response rate and temporal patterning (quarter-life) of rats performing either a previously learned fixed-interval schedule (FI 60) or learning an FI 60 simultaneously with stress onset were determined. Rats lived 24 h/day in operant cages, where they earned all of their food via lever-pressing. During the stress portion of each experiment, one group of rats was able to avoid or escape signalled intermittent footshock (Avoidance/ Escape Group), a second group (Yoked) did not have control over shock termination, a third group never received shock (Control). Shock trials were presented around the clock at approximately 5-min intervals and the stress portion of each study lasted 1-2 weeks. We have previously reported that rats tolerate this paradigm well and avoid/escape 99% of the shock trials. In rats previously trained on the FI task, both rate of responding and quarter-life values were significantly decreased on the first day of stress for both the Avoidance/Escape and Yoked Groups. Food intakes and quarter-life values were not significantly different from the controls by stress Days 3 and 2, respectively. In the acquisition study, controls learned the F1 task by Day 4 as judged by quarter-life of responding. FI task acquisition was significantly impaired in stressed rats compared to controls, not reaching asymptotic performance until Day 9 of stress. There were no major differences between the 2 stress groups in either study. These data demonstrate that stress may impair both the rate and patterning of behavior, and suggest that this rodent paradigm may usefully model some aspects of the effects of stress in humans.

Animals↗
PubMed1997

Cloning and expression of chitinases of Entamoebae.

Entamoeba histolytica (Eh) and Entamoeba dispar (Ed) are protozoan parasites that infect hundreds of millions of persons. In the colonic lumen, amebae form chitin-walled cysts, the infectious stage of the parasite. Entamoeba invadens (Ei), which infects reptiles and is a model for amebic encystation, produces chitin synthase and chitinase during encystation. Ei cysts formation is blocked by the chitinase-inhibitor allosamidin. Here molecular cloning techniques were used to identify homologous genes of Eh, Ed, and Ei that encode chitinases (EC 3.2.1.14). The Eh gene (Eh cht1) predicts a 507-amino acid (aa) enzyme, which has 93 and 74% positional identities with Ed and Ei chitinases, respectively. The Entamoeba chitinases have signal sequences, followed by acidic and hydrophilic sequences composed of multiple tandemly arranged 7-aa repeats (Eh and Ed) or repeats varying in length (Ei). The aa compositions of the chitinase repeats are similar to those of the repeats of the Eh and Ed Ser-rich proteins. The COOH-terminus of each chitinase has a catalytic domain, which resembles those of Brugia malayi (33% positional identity) and Manduca sexta (29%). Recombinant entamoeba chitinases are precipitated by chitin and show chitinase activity with chitooligosacharide substrates. Consistent with previous biochemical data, chitinase mRNAs are absent in Ei trophozoites and accumulate to maximal levels in Ei encysting for 48 h.

Amino Acid Sequence↗
PubMed1997

Mercury and organomercurial resistance in bacteria isolated from freshwater fish of wetland fisheries around Calcutta.

Mercury-resistant bacteria belonging to the genera Bacillus, Escherichia, Klebsiella, Micrococcus, Pseudomonas, Salmonella, Sarcina, Shigella, Staphylococcus and Streptococcus were isolated from gills and guts of fresh water fish collected from wetland fisheries around Calcutta, India, contaminated with mercury compounds. The total number of bacteria, as well as Hg-resistant bacteria, were always higher in guts than gills. Bottom-dwelling fish contained higher number of bacteria, including Hg-resistant bacteria, than surface and middle water dwelling fish. They belonged either to narrow-spectrum or to broad-spectrum Hg-resistant groups and they also possessed other heavy metal and antibiotic resistant properties. In the presence of toxic levels of HgCl(2), phenylmercuric acetate (PMA) and methylmercuric chloride (MMC), the lag in growth of the bacterial strains gradually increased with increasing concentration of Hg-compounds. Narrow-spectrum Hg-resistant bacterial strains volatilized only HgCl(2) from the liquid medium in the range of 64-89%, whereas the broad-spectrum group exhibited a high level of HgCl(2) (80-94%), PMA (72-84%) and MMC (64-80%) volatilizing capacity with inducible mercuric reductase and organomercurial lyase enzyme activities in their cell-free extracts. Cell-free extracts prepared from narrow-spectrum Hg-resistant bacterial strains induced by HgCl(2) exhibited Hg(+2)-dependent NADPH oxidation, indicating the presence of only mercuric reductase enzyme.

Journal Article↗
PubMed1997

Opiate modulation of striatal dopamine and hippocampal norepinephrine release following morphine withdrawal.

When opiates are abruptly withdrawn after chronic treatment, increases in hippocampal noradrenergic function are observed which are accompanied by decreases in striatal dopamine release. The latter effects have to shown to persist for several weeks following the onset of opiate withdrawal. We examined the long-term effects of opiate withdrawal on 4-aminopyridine and potassium stimulated release of striatal dopamine and hippocampal norepinephrine. Tissue samples were obtained either from rats that had been exposed to opiate withdrawal following a seven day morphine infusion or sham treated control subjects. At 48 hours after the onset of withdrawal (cessation of morphine infusions), slices were loaded with [3H] neurotransmitter, washed extensively, and exposed to different drug treatments. 4-aminopyridine induced concentration related increases in striatal dopamine release, which was 36% calcium independent. Similar values for fractional release of striatal dopamine were obtained in morphine withdrawn and control subjects, for both potassium and 4-aminopyridine induced release. In addition, thresholds for 4-aminopyridine or potassium induced release of striatal dopamine did not differ between control and morphine withdrawn subjects. Treatment with 1.0 microM morphine sulfate potentiated potassium evoked release of norepinephrine to an equal extent in both morphine withdrawn and sham treated hippocampal tissue. Exposure to a threshold concentration of potassium (8.0 mM), stimulated increased release of hippocampal norepinephrine in a significantly greater fraction of tissue samples obtained from morphine withdrawn animals. Although these results do not support changes in striatal dopamine release following opiate withdrawal, opiate mechanisms appear to be important determinants of in vitro hippocampal norepinephrine release.

4-Aminopyridine↗
PubMed1997

Fas activates NF-kappaB and induces apoptosis in T-cell lines by signaling pathways distinct from those induced by TNF-alpha.

The p55 tumor necrosis factor (TNF) receptor and the Fas (CD95/APO-1) receptor share an intracellular domain necessary to induce apoptosis, suggesting they utilize common signaling pathways. To define pathways triggered by Fas and TNF-alpha we utilized human CEM-C7 T-cells. As expected, stimulation of either receptor induced apoptosis and TNF-alpha-induced signaling included the activation of NF-kappaB. Surprisingly, Fas-induced signaling also triggered the activation of NF-kappaB in T cells, yet the kinetics of NF-kappaB induction by Fas was markedly delayed. NF-kappaB activation by both pathways was persistent and due to the sequential degradation of IkappaB-alpha and IkappaB-beta. However, the kinetics of IkappaB degradation were different and there were differential effects of protease inhibitors and antioxidants on NF-kappaB activation. Signaling pathways leading to activation of apoptosis were similarly separable and were also independent of NF-kappaB activation. Thus, the Fas and TNF receptors utilize distinct signal transduction pathways in T-cells to induce NF-kappaB and apoptosis.

Journal Article↗
PubMed1997

Epidemiological study of hypertension and its determinants in an urban population of North India.

OBJECTIVES: To determine age-specific prevalence of hypertension and blood pressure (BP) levels in relation to diet and lifestyle factors in North Indians. DESIGN AND SETTING: Cross-sectional survey in 20 randomly selected streets in Moradabad, North India. SUBJECTS AND METHODS: A total of 1806 subjects from North India (904 males and 902 females) age range 25-64 years. The survey methods were as follows: dietary diaries for 7 days food intake record; BP measurements; physician administered questionnaire and anthropometric measurements. Diagnosis of hypertension was based on new World Health Organization/International Society of Hypertension (WHO/ISH) criteria. Risk factors were assessed based on WHO guidelines. RESULTS: The prevalence of hypertension according to WHO/ISH criteria was 23.7% and by old WHO criteria 13.3%. In the WHO/ISH hypertensive group, isolated diastolic hypertension was present in 47.3% males and 40.6% females. Males have a slightly higher prevalence than females in the young age group, however, the prevalence rates are comparable in the older age groups. In both sexes, the prevalence rates and BP level increased with older age. Multivariate analysis revealed that age, higher body mass index, central obesity and higher socioeconomic status were independently and strongly associated with hypertension in both sexes. Higher dietary fat and salt intake and lower physical activity were weakly but significantly associated with hypertension. CONCLUSION: Association of higher socioeconmic status, higher body mass index and central obesity in North Indian adults with higher fat intake, lower physical activity and higher prevalence and level of hypertension indicate that these populations may benefit by decreasing the dietary fat intake and increasing physical activity, with an aim to decrease central obesity for decreasing hypertension in North Indians.

Adult↗
PubMed1997

Cerebral calcium fluxes and calcium homeostasis in the rat: a minimal model.

Disturbance of calcium homeostasis and unregulated increase in intracellular calcium have been implicated in cell damage and cell death in the central nervous system in particular. To determine the specific pathway(s) of cerebral Ca transport of importance in a pathophysiological situation, we have measured long term Ca flux in brain in vivo in rat, and developed a kinetic model incorporating physiologically relevant pathways of cerebral Ca transport. 45Ca was injected into a tail vein in conscious rats. Plasma 45Ca was monitored up to 4 days post-injection and 45Ca uptake determined in samples of cerebrospinal fluid (CSF) and at several sites of brain at euthanasia. Uptake of the tracer by tissues peaked after 1 h, isotopic equilibration taking longer. The uptake at hippocampus was the highest. Computer simulation of the kinetics of the plasma, CSF and tissue data was performed using a compartmental model, which included two subcompartments (intra- and extra-cellular) and two pathways from plasma to the brain: directly across the blood-brain barrier and via CSF, which included a delay. The analysis based on this model enabled estimation of the fractional rates of transport of Ca to cerebral and noncerebral tissues across all the barriers of the model.

Animals↗
PubMed1997

Epidemiologic study of trace elements and magnesium on risk of coronary artery disease in rural and urban Indian populations.

OBJECTIVE: To determine the association of trace elements and magnesium with risk of coronary artery disease (CAD) in rural and urban populations of India. DESIGN AND SETTING: Cross-sectional surveys on the randomly selected municipal streets in Moradabad city and one village in Moradabad tahsil in North India. SUBJECTS AND METHODS: There were 162 rural (86 men and 96 women) and 152 urban (80 men and 72 women) subjects between 26 to 65 years of age. Evaluations were obtained by physician- and dietitian-administered, validated questionnaires, physical examination, electrocardiogram and blood examination. RESULTS: The prevalence of CAD and coronary risk factors was 2.5 times higher in the urban population compared to rural subjects (8.6 vs. 3.0%). In rural subjects, dietary intakes and plasma levels of vitamins and minerals were comparable with those of urban subjects except for higher dietary intake of magnesium in rural subjects and higher plasma vitamin A level in urban subjects. In both rural and urban subjects, low serum zinc (80 +/- 82 vs. 110 +/- 11.0 micrograms/dl, p < 0.05) and magnesium levels (1.60 +/- 0.36 vs. 1.71 +/- 0.41 mEQ/L, p < 0.05) and lower zinc/copper ratio (0.58 +/- 0.08 vs. 1.11 +/- 0.25 p < 0.50) were inversely associated with CAD. Serum levels of copper and iron were significantly higher and plasma levels of antioxidant vitamins A, E and C and beta-carotene were significantly lower in patients with CAD compared to the rest of the subjects. In both rural (7.1 +/- 1.2 mg/day) and urban subjects (8.6 +/- 1.6 mg/day), zinc consumption was half of the recommended dietary allowances. Higher prevalence of CAD in urban compared to rural subjects was attributed to higher dietary fat intake and higher prevalence of risk factors in urban subjects. CONCLUSIONS: The findings suggest that lower serum levels of zinc and magnesium and lower zinc copper ratio were inversely associated with CAD. It is possible that urban populations with higher risk of CAD may benefit by decreasing dietary fat intake and by increasing their intake of foods rich in zinc and magnesium.

Adult↗
PubMed1997

Selective excitation of tryptophans in OmpF: a fluorescence emission study.

The fluorescence studies of E. coli porin OmpF at pH 7.5 were carried out using excitation at 280 and 305 nm. Similar studies were performed in presence of a denaturant (urea) and a quencher (KI). Results show that both the tryptophans present in OmpF (residue numbers 61 and 214) contribute to fluorescence at 280 nm excitation, whereas only one residue shows fluorescence emission when excited at 305 nm. Based on these findings and the available crystal structure, it is speculated that tryptophan 61 of OmpF is selectively excited at 305 nm. The present studies point out some interesting features of the tryptophan microenvironments in OmpF.

Bacterial Outer Membrane Proteins↗
PubMed1997

Social class and coronary disease in rural population of north India. The Indian Social Class and Heart Survey.

OBJECTIVE: To demonstrate the association of socio-economic status with prevalence of coronary artery disease and coronary risk factors. DESIGN AND SETTING: Cross-sectional survey in two randomly selected villages in the Moradabad district in North India. SUBJECTS AND METHODS: One thousand seven hundred and sixty-seven subjects (894 males and 875 females; 25-64 years of age) were randomly selected from two villages. They were divided into social classes 1 to 4, according to education, occupation, housing conditions, ownership of land, ownership of consumer durables and per capita income. The survey was based on questionnaires administered by dietitians and physicians, physical examination and electrocardiography. RESULTS: Social classes 1 and 2 were mainly high and middle socio-economic groups and 3 and 4 low income groups. The prevalence of coronary artery disease was significantly higher among classes 1 and 2 in both sexes, and there was a higher prevalence of hypercholesterolaemia, hypertension, and sedentary lifestyle. This population also showed a significant association with higher serum cholesterol, body mass index, triglycerides and blood pressures. Logistic regression analysis with adjustment for age showed that social class positively related to coronary disease (odds ratio: men 0.83, women 0.61), hypercholesterolaemia (men 0.85, women 0.87), hypertension (men 0.89, women 0.87), body mass index (men 0.91, women 0.93) and smoking in men (0.68). Smoking and sedentary lifestyle were not associated with social class in women. The association between coronary artery disease and social class abated after adjustment for smoking, sedentary lifestyle, body mass index and blood pressure (odds ratio: men 0.96, women 0.81). CONCLUSION: Subjects in social classes 1 and 2 in rural North India have a higher prevalence of coronary artery disease and of the coronary risk factors hypercholesterolaemia, hypertension, higher body mass index and sedentary lifestyle. The overall prevalence of coronary artery disease was 3.3%.

Adult↗
PubMed1997

A receptor for the oocyte maturation-inducing hormone 17alpha,20beta,21-trihydroxy-4-pregnen-3-one on ovarian membranes of striped bass.

Previous studies have shown that blood plasma levels of 17alpha, 20beta-dihydroxy-4-pregnen-3-one (DHP) and 17alpha, 20beta, 21-trihydroxy-4-pregnen-3-one (20beta-S) increase in striped bass (Morone saxatilis) undergoing final oocyte maturation (FOM). Both hormones are produced by ovarian fragments undergoing hCG-induced germinal vesicle breakdown (GVBD) in vitro. In the present study, we investigated binding of DHP and 20beta-S to ovarian membranes from striped bass undergoing FOM. Saturable binding sites for DHP were not detected. Saturation of 20beta-S binding sites with 5 nM [3H]20beta-S occurred within 40 min at 0 degrees C (at 3 min, half of the maximum specific binding of steroid was calculated to have occurred), and the binding was pH-dependent. Scatchard analyses revealed the presence of a single class of high-affinity (dissociation constant [Kd] = 1.4 +/- 0.2 nM), limited-capacity (estimated concentration [Bmax] = 2.7 +/- 0.3 pmol/g ovary) 20beta-S binding sites on membranes from striped bass ovaries undergoing FOM. In contrast, only low levels of specific binding (Bmax < 0.04 pmol/g tissue) were detected on membranes from testes, liver, brain, and muscle. Ovarian membranes prepared from vitellogenic females also had low levels (Bmax < 0.1 pmol/g ovary) of specific 20beta-S binding, less than 5% of that found during FOM. Results of competition assays showed that DHP was approximately 250 times less effective than 20beta-S for displacing 20beta-S from ovarian membranes. In contrast, 20beta, 21-dihydroxy-4-pregnen-3-one was a very effective competitor, although it is only a weak inducer of oocyte GVBD in vitro. Of several other steroids tested, only progesterone showed affinity for the 20beta-S binding site within a physiological range of concentrations. Taken together with previous studies of striped bass FOM, these findings indicate that 20beta-S is the oocyte maturation-inducing steroid hormone in striped bass.

Animals↗
PubMed1997

Lipid biochemistry: functions of glycerolipids and sphingolipids in cellular signaling.

Products of glycerolipid and sphingolipid metabolism are now known to fulfill second messenger functions in a variety of cellular signaling pathways. Evidence for glycerolipid-derived second messengers was first obtained from the "phosphatidylinositol cycle," which involves a signal-dependent hydrolysis of phosphatidylinositol bisphosphate yielding diacylglycerol and inositol trisphosphate. The role of diacylglycerol in the regulation of protein kinase C activity and its site of interaction with PKC are now well known. Recently, another glycerolipid second messenger, phosphatidic acid, was found to interact with the protooncogenic Raf-1 kinase. In cultured cells, a signal-induced generation of phosphatidic acid was critical for Raf-1 translocation to the cell membrane. Thus, different glycerolipid second messengers appear to regulate distinct targets with exquisite specificity. Analogous to the PI cycle, a "sphingomyelin cycle" was also found to exist, generating sphingolipid second messengers. Ceramide, derived from the agonist-induced hydrolysis of sphingomyelin, is a potent biomolecule with effects in multiple cell signaling pathways. The steroid hormone progesterone stimulated sphingomyelin hydrolysis in Xenopus oocytes. Ceramide, derived from the "sphingomyelin cycle," was sufficient for meiotic cell cycle progression in the oocytes. These results demonstrate the various effects of lipid-derived second messengers and promise exciting discoveries into the roles of lipids in cell signaling.

Animals↗
PubMed1997

Detection of insulin-like growth factor-I and transforming growth factor-beta in whole gut lavage fluid: a novel method of studying intestinal fibrosis.

BACKGROUND: Insulin-like growth factor-I (IGF-I) and/or transforming growth factor-beta (IGF-beta), may be involved in gut fibrous strictures. METHODS: Concentrations of these two peptides have been measured by enzyme-linked immunosorbent assays (ELISAs) in whole gut lavage fluid from 57 patients, of whom 14 had strictures of the small intestine or colon associated with Crohn's disease, irradiation injury, ischaemia or diverticulitis. RESULTS: IGF-I was detected in fluid from 11 of 14 patients with strictures, and 5 of 43 others (P < 0.01). TGF-beta was detectable in all 57 samples and concentrations were unrelated to the presence or absence of strictures. CONCLUSION: Clinical studies of growth factors in intestinal fluid should facilitate research on intestinal fibrogenesis, and the diagnosis of fibrous stricturing in Crohn's disease.

Crohn Disease↗
PubMed1997

Diagnostic use of endoscopic mucosal resection.

We report two cases of gastric carcinoma where repeated, multiple conventional endoscopic biopsies were falsely negative. Endoscopic mucosal resection gave a positive diagnosis in both these patients. New equipment for aspiration mucosectomy makes the technique easier to perform, and a larger, deeper biopsy is obtained.

Adenocarcinoma↗
PubMed1997

Successful pregnancy in a patient with chronic intestinal pseudo-obstruction while on ambulatory percutaneous endoscopic gastrostomy feeding.

We report a case of ambulatory endoscopic gastrostomy feeding via a low profile button device using a portable feeding pump. This provided successful nutritional support to a patient with chronic intestinal pseudo-obstruction who became pregnant while on gastrostomy feeding. She successfully completed her pregnancy with nutritional support through the gastrostomy. The portable feeding pump gave her excellent quality of life both indoors and outdoors, and she could continue feeding without interrupting her daily housework, shopping and babycare.

Adult↗
PubMed1997

Body composition at the bedside.

OBJECTIVE: To evaluate the use of an inexpensive hand-held bioelectric impedance analysis machine which measures lean body mass, by technical comparisons against standard instruments and techniques (an in-house bioelectric impedance machine and dual energy X-ray absorptiometry), and by performing body composition analyses in groups of potentially malnourished patients. DESIGN: Prospective simultaneous comparison of measurements made by the hand-held and in-house bioelectric analysis machines and dual energy x-ray absorptiometry. SETTING: Medical Physics Department and Gastrointestinal Unit in a university teaching hospital. SUBJECTS/METHODS: One hundred and sixty subjects were recruited into the study. Data from 58 adolescent and 14 adult volunteers and from 42 adult patients were used for technical comparisons (n = 114). Body composition information was evaluated (n = 102) for 60 adult volunteers and 42 patients (17 with eating disorders, 7 with chronic alcoholic pancreatitis and 18 with inflammatory bowel disease). OUTCOME MEASURES: Estimation of bias, limits of agreement and correlations on data from the three machines. Relationships between percentage body mass as lean, absolute weights and body mass index, in the adult subjects. RESULTS: Both resistance and calculated impedance measured by the hand-held machine significantly correlated with the impedance measured by the in-house machine (r = 0.996; P < 0.0001). An estimation of the level of agreement in percentage lean measurement between dual energy x-ray absorptiometry and hand-held bioelectrical impedance analysis machine by the Bland and Altman method showed a bias of -0.07% and satisfactory limits of agreement from -7.97% to 7.76%. Body mass index was similar in the groups of healthy men and women, but proportion of weight as lean was significantly higher in men than women. In underweight patients with eating disorders, the ratio of lean to fat varied widely; in inflammatory bowel disease patients, proportions of lean and fat were similar to controls; however patients with alcoholic pancreatitis had values for body mass index similar to controls, but had significantly lower proportion of their body weight as lean (P < 0.05). CONCLUSION: In non-obese and thin adults, an accurate two-compartment (lean, fat) measurement of body composition can be made in 10 min by using an inexpensive, hand-held, bioelectric impedance analysis machine.

Absorptiometry, Photon↗