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S Das Gupta

Publications and source records attributed to S Das Gupta.

At least 19 recordsLinked to original sources
PubMed2003

Ptychodiscus brevis toxin enhances the frequency-dependent depression of the monosynaptic reflex in neonatal rat spinal cord in vitro.

The involvement of frequency-dependent depression (FDD) of synaptic transmission for the depressant action of the Ptychodiscus brevis toxin (PbTx) was investigated in neonatal rat spinal cord in vitro. The stimulation of a dorsal root by train of pulses (five stimuli) at different frequencies evoked potentials in the ventral root (monosynaptic reflex, MSR). Amplitude of the fifth response as percent of first response at 0.1, 0.2, 0.5, 1.0 and 2.0 Hz were 90, 80, 75, 70 and 50%, respectively. In Mg2+-free medium, PbTx depressed the MSR and also enhanced the FDD in a concentration-dependent manner. Further, the PbTx-induced depression can well be correlated with the enhancement of FDD (r=0.98). In the presence of Mg2+ (1.3 mM), the FDD was greater than that in the absence of Mg2+. But in the presence of Mg2+ PbTx did not alter FDD, even though there was 25% depression at 28 microM (significantly lesser than in Mg2+-free medium). The results indicate that the Mg2+-sensitive component of PbTx-induced depression of MSR is mediated via the neuronal systems involving FDD.

Action Potentials↗
PubMed2002

Relative potency of synthetic analogs of Ptychodiscus brevis toxin in depressing synaptic transmission evoked in neonatal rat spinal cord in vitro.

Effects of Ptychodiscus brevis toxin (PbTx) analogs on the spinal synaptic transmission in neonatal rats in vitro were evaluated. PbTx1/PbTx2 had aromatic groups and PbTx3/PbTx4 had aliphatic groups. All the analogs depressed monosynaptic reflex (MSR) and polysynaptic reflex (PSR) in a concentration-dependent manner. The maximal depression of MSR (75% from initial) and PSR (96%) was at 84 microM for PbTx1. Concentration to produce 25% inhibition from initial (IC25) by PbTx1 for MSR and PSR was < or =2.8 microM. The maximal depression of MSR (80%) was at 96 microM and PSR (100%) was at 32 microM by PbTx2. IC25 for MSR and PSR were 5.5 microM and <3.2 microM, respectively. PbTx3 decreased MSR by 25% maximally (=IC25) at 36 microM. The depression of PSR fluctuated and was maximal (75%) at 108 microM and IC25 was 6.2 microM. PbTx4 depressed MSR and PSR at the maximum of 35% at 32 microM and IC25 for MSR was 8.3 microM and for PSR was 35 microM. Rank order of potency of toxins for depressing MSR was PbTx1>PbTx2>>PbTx4>PbTx3; and for PSR it was PbTx2>PbTx1>PbTx3>>PbTx4. Results indicate that the toxins having aromatic groups exhibited greater neurotoxicity.

Animals↗
PubMed2002

Changing scenario of transfusion-related viral infections.

OBJECTIVE: To study the changing incidence of blood transfusion-related viral infections consequent to compulsory screening of blood and greater awareness of the problem, over the last five years. METHODS: This is a cross-sectional study carried out at Medical College, Calcutta. Three groups each consisting of 100 subjects were selected for this study. Group A comprised multiple transfused patients who have also received transfusion before 1995. Group B comprised patients who had received transfusions only since 1995. Group C comprised of control patients who have never been transfused. The incidence of HBsAg +ve, anti-HCV +ve and HIV +ve cases were calculated and expressed as percentages and compared using the chi square test. RESULTS: The incidences of HBsAg +ve and anti-HCV +ve cases in the three groups were 20% and 16% in Group A, 7% and 6% in Group B and 4% and 2% in Group C. The difference between Group A and Group B were statistically significant. CONCLUSION: The incidence of HBsAg and anti-HCV positive cases among the multi-transfused has decreased over the last five years.

Adolescent↗
PubMed2001

Tuberculosis and patient gender in Bangladesh: sex differences in diagnosis and treatment outcome.

SETTING: The public health sector of Bangladesh. OBJECTIVE: To assess gender differences in access to tuberculosis diagnosis and in tuberculosis treatment outcome in Bangladesh. METHODS: Information on the age and sex of a sample of patients in 1997 was collected from out-patient registers and tuberculosis laboratory and treatment registers in 59 thanas in three divisions in Bangladesh. RESULTS: The female/male ratio was 0.79 among 42,877 out-patients with respiratory complaints, 0.51 among 5,665 tuberculosis suspects undergoing sputum smear microscopy, 0.36 among 869 tuberculosis suspects with positive sputum smears, and 0.35 among 5,632 patients registered for tuberculosis treatment. Treatment was successful (cured or treatment completed) in 86% of female and 84% of male patients. CONCLUSION: Women in Bangladesh appear to have less access to public out-patient clinics than men, and if they present with respiratory symptoms they are less likely to undergo sputum smear examination. If examined, women are less likely than men to be smear-positive. No gender bias was observed in tuberculosis treatment outcome. It is recommended to focus further research on exploration of sex differences in the incidence of respiratory conditions, identification of constraints among women in accessing out-patient clinics and verification of the quality of sputum submitted by women for examination.

Adolescent↗
PubMed1999

Effect of high arsenic content in drinking water on rat brain.

The permissible limit of arsenic content in drinking water is 0.05 ppm, whereas, in many parts of West Bengal the arsenic level in drinking water is 0.1 ppm, frequently 0.3 ppm and even 3.0 ppm, though rarely. In order to assess possible risk to brain function by drinking such water, rats were given arsenic mixed in drinking water at the above four concentrations for 40 days. There was increased lipid peroxidation at all doses of arsenic, including the 'permissible limit', decrease in glutathione level, superoxide dismutase and glutathione reductase activities, indicating the free-radical-mediated degeneration of brain.

Animals↗
PubMed1998

A report of diphtheria surveillance from a rural medical college hospital.

A 5-year sentinel surveillance of diphtheria from 1989 to 1993 was undertaken at a rural medical college hospital. No significant change in the number of diphtheria cases was observed in spite of sustained high level of diphtheria, pertussis, tetanus vaccine-3 doses (DPT3) coverage. Most of the diphtheria cases occurred during July to November. Age distribution of diphtheria cases showed that more than 75% occurred above 2 years age (except in 1989) and around 65% cases above 3 years age. The age shift in diphtheria signified success of primary diphtheria immunisation, as well as indicated the lack of coverage with booster doses at appropriate ages. Because of high coverage with primary diphtheria immunisation there was decrease in circulating toxigenic C diphtheriae resulting in less natural boosting of antibody titre. Thus, in absence of booster immunisation, the older children and adults were more vulnerable to diphtheria. The findings of the study justified the need of emphasising importance of booster diphtheria immunisation at appropriate ages for effective control of diphtheria.

Adult↗
PubMed1995

A comparative study of delayed neurotoxicity in hens following repeated administration of organophosphorus compounds.

Hens treated with Mipafox (10 mg/kg, sc), sarin (50 micrograms/kg, sc) or parathion (1 mg/kg, sc) daily for 10 days exhibited severe, moderate and no ataxia respectively on 14th day after the start of exposure. The neurotoxic esterase (NTE) activity was significantly inhibited in the brain, spinal cord and platelets of hens treated with mipafox or sarin whereas no change was noticed with parathion treatment. All three compounds significantly inhibited acetylcholinesterase (AChE) activity in the platelets. Spinal cord of hens treated with mipafox, sarin or parathion showed axonal degeneration heavy, moderate and none respectively. It is concluded that repeated administration of equitoxic doses of mipafox, sarin and parathion to hens are marked, moderate and non-delayed neurotoxic respectively.

Animals↗
PubMed1993

Biphasic action of sarin on monosynaptic reflex in the neonatal rat spinal cord in vitro.

The action of sarin, an organophosphorus (OP) compound, was examined in vitro for its effects on the spinal monosynaptic reflex (MSR) in neonatal rats. The effects of sarin were biphasic, i.e. facilitation at lower concentrations (2-20 nM) followed by depression of the MSR at concentrations above 30 nM. Facilitation of MSR was maximal (150% of control) at 20 nM sarin. The depression of MSR was maximal (70% of control) at 200 nM sarin, with half maximal inhibition occurring at 90 nM sarin. Atropine (200-500 nM) effectively reversed the depression caused by sarin, while pretreatment with low concentrations of atropine (10 nM) completely blocked the depression otherwise observed with sarin. Benactyzine was also effective in preventing sarin-induced depression, while pirenzepine was less effective. The nicotinic blocking agents tubocurarine and mecamylamine were, however, ineffective in preventing or reversing sarin-induced depression. The facilitation of MSR seen with lower concentrations (2-20 nM) correlated well with the blockade of late phase inhibition (between 30 and 50 ms conditioning-test interval) elicited in spinal cord by stimulating the adjacent dorsal root at various condition-test intervals, which has been shown elsewhere to be sensitive to bicuculline (Deshpande and Warnick 1988). Thus it is speculated that sarin at lower concentrations blocks GABA transmission, producing facilitation, and at higher concentrations activates the muscarinic receptors producing depression of MSR. The beneficial action of pretreatment with antimuscarinic agents may be attributed to the protection of the muscarinic receptors.

Animals↗
PubMed1993

Mobilization and distribution of beryllium over the course of chelation therapy with some polyaminocarboxylic acids in the rat.

The efficacy of three common polyaminocarboxylic acids in the treatment of experimental beryllium intoxication was investigated in male rats. N-(2-hydroxyethyl) ethylene diamine triacetic acid (HEDTA) was more effective than calcium disodium ethylenediamine tetraacetic acid (CaNa2EDTA) in reducing the beryllium concentration of the blood, kidneys and spleen and reducing beryllium-induced inhibition of hepatic alkaline phosphatase activity. HEDTA was also most effective in reducing histopathological lesions in the liver and spleen. Compared to these two chelators, the third amino chelator, calcium trisodium diethylene triaminepenta acetic acid (CaNa3DTPA) produced severe deleterious effects in the liver and systemic toxicity. The results suggest that HEDTA is a promising chelator for beryllium toxicity while DTPA enhances the toxic manifestation of beryllium.

Animals↗
PubMed1993

Protection against cyanide poisoning by the co-administration of sodium nitrite and hydroxylamine in rats.

1. The protectiveness of combined treatment with sodium nitrite (SN) and hydroxylamine (HA) in cyanide intoxication was investigated in male rats. 2. Pretreatment with equimolar dose of SN or HA produced a significant protection against cyanide poisoning as shown by the protection index (LD50 of cyanide in protected rats/LD50 of cyanide in saline-treated rats). 3. The co-administration of SN and HA as a split dose produced an optimal and sustained methaemoglobinaemia. 4. Pretreatment with combined SN and HA administration at different time intervals offered sustained protection against cyanide and resultant cytochrome oxidase inhibition. 5. Adjunction of sodium thiosulphate (STS) in the SN+HA regimen further augmented the protection against cyanide poisoning. 6. The results suggest that pretreatment with SN+HA co-administration could significantly reduce the toxic manifestation of cyanide.

Animals↗
PubMed1993

Influence of pretreatment of carbamates on dynamic pulmonary mechanics in rats exposed to sarin aerosols.

The effect of pretreatment of two carbamates, pyridostigmine and physostigmine on dynamic pulmonary mechanics has been studied in rats exposed to sarin aerosols. Sign-free dose of pyridostigmine (0.075 mg/kg, i.m.) or physostigmine (0.1 mg/kg, i.m.) did not significantly alter the parameters of the dynamic pulmonary mechanics 20 min after treatment. However, sarin (51.2 mg/m3, for 15 min) depressed the respiratory rate, air flow and minute volume and enhanced the transthoracic pressure and tidal volume. Pretreatment with carbamates 20 min prior to sarin exposure significantly modified or counteracted the above induced changes. It is concluded that the protective effect of carbamates is mainly due to the correction of respiratory changes caused by sarin aerosols in rats.

Aerosols↗
PubMed1993

Sarin induced lung pathology and protection by standard therapy regime.

The effects of atropine, diazepam and pralidoxime were studied for their ability to block the pathological lesions induced by sarin. Rats were exposed to an aerosol of sarin at a concentration of 51.2mg.m-3 for 15 min following the pretreatment with one of the following combinations: atropine (10 mg/kg, i.m.) and diazepam (0.5 mg/kg, i.m.); atropine and pralidoxime (25 mg/kg, i.m.); diazepam and pralidoxime; atropine, diazepam and pralidoxime. Lung exposed to sarin aerosols revealed an increased cellular proliferation with progressive diffused interstitial thickening on the 4th day following exposure. On the 16th day, loss of alveolar space and consolidation of large areas of all lobes were observed. Sarin also caused damage to the respiratory bronchioles. All the therapy regime blocked the development of lung lesions in the descending orders: atropine, diazepam and pralidoxime, atropine and diazepam > diazepam and pralidoxime > atropine and pralidoxime. The result suggests that diazepam in combination with atropine and pralidoxime could be an effective drug combination regime for the lung lesions.

Animals↗
PubMed1992

Effect of single gallium arsenide exposure on some biochemical variables in porphyrin metabolism in rats.

Gallium arsenide (GaAs) inhibited, dose dependently, delta-aminolevulinic acid dehydratase (ALAD) activity in blood (as observed on days 1, 7 and 15), liver and brain (on day 15) after a single oral treatment. Levels of blood zinc protoporphyrin (ZPP) and urinary delta-aminolevulinic acid (ALA) excretion were elevated on day 7 and day 15 following exposure to 2000 mg kg-1 GaAs. A dose-dependent increase in blood As contents was observed while blood Ga was detectable only at higher doses.

Administration, Oral↗
PubMed1992

The 3,3'-bis-pyridinium mono-oximes as antidotes against organophosphorous intoxication.

In an attempt to develop effective antidotes against organophosphorous intoxication, three new structurally related bispyridinium mono-oximes with a 2-oxopropane bridge were synthesized. The compounds were evaluated for in-vivo therapeutic protection and cholinesterase reactivation in blood and various brain regions. In neuromuscular function studies against diisopropyl-fluorophosphate and isopropyl methylphosphonofluoridate poisoning, the oximes produced significant protection. The compounds produced marked peripheral reactivation and beneficial effects on neuromuscular transmission. The reactivation of cholinesterase in cerebral cortex by the oximes, in spite of their being quaternary salts is a notable feature.

Animals↗