Persistence and transformation of thiamethoxam, a neonicotinoid insecticide, in soil of different agroclimatic zones of India.
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Carbon↗
Biomedical subjects
R Karmakar
Publications and source records attributed to R Karmakar.
Precise toppling balance, quenched disorder, and universality for sandpiles.
A single sandpile model with quenched random toppling matrices captures the crucial features of different models of self-organized criticality. With symmetric matrices avalanche statistics falls in the multiscaling Bak-Tang-Wiesenfeld universality class. In the asymmetric case the simple scaling of the Manna model is observed. The presence or absence of a precise toppling balance between the amount of sand released by a toppling site and the total quantity the same site receives when all its neighbors topple once determines the appropriate universality class.
Journal Article↗
Sandpile model on a quenched substrate generated by kinetic self-avoiding trails.
Kinetic self-avoiding trails are introduced and used to generate a substrate of randomly quenched flow vectors. A sandpile model is studied on such a substrate with asymmetric toppling matrices where the precise balance between the net outflow of grains from a toppling site, and the total inflow of grains to the same site when all its neighbors topple once, is maintained at all sites. Within numerical accuracy this model behaves in the same way as the multiscaling Bak, Tang, and Wiesenfeld model.
Journal Article↗
Directed fixed energy sandpile model.
We numerically study the directed version of the fixed energy sandpile. On a closed square lattice, the dynamical evolution of a fixed density of sand grains is studied. The activity of the system shows a continuous phase transition around a critical density. While the deterministic version has the set of nontrivial exponents, the stochastic model is characterized by mean field like exponents.
Journal Article↗
Phase-transfer catalyst-induced changes in the absorption and fluorescence behavior of some electron donor-acceptor molecules.
The quaternary ammonium salts find extensive use in a variety of chemical applications as surfactants and phase-transfer catalysts. Even though the interaction of the surfactants with various systems has been studied rather extensively, very little information is available on how the phase-transfer catalysts (PTC) interact with the dipolar systems in nonpolar media and how/whether these solubilizing agents affect the properties of the dissolved molecules. In this paper, the interaction of several tetraalkylammonium salts, commonly used as PTC, with a number of electron donor-acceptor (EDA) systems has been studied by absorption and fluorescence spectroscopy. The phase-transfer catalysts have been found to affect both the absorption and fluorescence properties of the EDA systems. The spectral changes of the EDA molecules induced by the tetraalkylammonium salts suggest the formation of an 1:1 complex between the two in nonpolar media. An electrostatic interaction between the phase-transfer catalysts (which exist as ion pairs in nonpolar media) and the dipolar molecules is shown to be the driving force for the formation of the complex. The dependence of the formation constant of the complex on the polarity of the media suggests a charge-transfer nature of the complex. It is shown that the anionic component of the salts serves as a source of electron to the positive end of the dipolar molecule, while the tetraalkylammonium cation, besides helping solubilization of its anionic counterpart in the nonpolar media, serves neutralizing the negative charge at the acceptor end of the EDA molecule. In effect, a cooperative influence of the cationic and anionic components of the PTC enhances the charge separation within the dipolar fluorophores. On the basis of the PTC-induced changes in the photophysical behavior of the EDA molecules, a possible structure for the 1:1 complex has been proposed. It has been concluded that a phase-transfer catalyst should not be treated as an innocuous substance that merely helps transfer of a polar substance from a polar to a nonpolar environment. Instead, it is demonstrated that the association of a PTC with a dipolar species can significantly change various properties of the latter.
Journal Article↗
Anticlastogenic potential of 1alpha,25-dihydroxyvitamin D3 in murine lymphoma.
Vitamin D3, having gained scientific interest for so long because of its role in mineral homeostasis, has now received great importance as a possible antitumor agent. This study was undertaken in an attempt to visualize the possible anticlastogenic potential of the vitamin in an ascitic mouse lymphoma model namely, Dalton's lymphoma. Frequencies of structural type chromosomal aberrations, sister chromatid exchanges and micronucleus assays have been chosen as the genotoxic endpoints in the proposed investigation. All these cytogenetic markers have been found to be markedly elevated during the progression of lymphoma in bone marrow cells. Vitamin D3 effectively suppressed the frequencies of chromosomal aberrations and sister chromatid exchanges in the lymphoma-bearing mice during the entire phase of tumor growth that significantly coupled with almost two-fold increase in survival time (37 +/- 2 and 68 +/- 2 days in lymphoma controls and vitamin D3-treated lymphoma-bearing mice, respectively), thus substantiating the antineoplastic efficacy of this secosteroid. The outcome of this study also is clearly reflected in the depletion of circulating (serum) vitamin D3 levels in the lymphoma control mice compared with normal (vehicle) controls while a still higher level was maintained in the VD3-treated lymphoma mice. This anticlastogenic property of the vitamin has so far been neglected and this is the first attempt to unravel the vitamin D3's effect in combating tumor development in vivo by limiting the frequencies of chromosomal aberrations, sister chromatid exchanges and micronuclei at least in transplantable murine model studied herein.
Animals↗
Biochemical, haematological and histopathological study in relation to time-related cadmium-induced hepatotoxicity in mice.
In the present investigation sub-chronic hepatic necrosis was induced by cadmium chloride and was examined biochemically, haematologically and histopathologically in order to study the time-dependent effect and correlation among the parameters. Male Balb/c mice were injected with cadmium chloride (2.5 mg/kg bw s.c.) for each other day and, sacrificed on the 7th day, 14th day and 21th day post exposure. Body weight and relative liver weight did not show alteration at any of the time point following the treatment but the tissue cadmium level showed progressive significant increment values with the advancement of time exposure. Most of the biochemical parameters (total protein, DNA, RNA, cytochrome P450 cotents, alkaline phosphatase and UDP glucuronyl transferase activities), haematological parameters (total red blood cells, total white blood cell, differential white blood cell counts, haemoglobin, erythrocyte sedimentation rate, serum glutamic oxaloacetic transaminase, serum glutamic pyruvic transaminase, plasma protein) indicated either no or less on the alterations/7th day following cadmium exposure. Both the light and transmission electron microscopy, on the other hand, indicated the fact that a minimum of 21 day-exposure was needed to alter the cellular architecture. So, a certain amount of cadmium load might be required to adversely affect the cellular architecture preceeded by biochemical and haematological alterations. In this connection, in the present study a possible mechanism of cadmium-induced hepatoxicity was discussed.
Animals↗
Effect of vitamin D3 on carcinogen-modified liver enzymes and tumour incidence in experimental rat mammary carcinogenesis.
The anticarcinogenic effect of vitamin D3 in relation to biochemical and morphological markers in 7,12-dimethylbenz(alpha)anthracene (DMBA)-induced mammary carcinogenesis was investigated in two different sets of experiments. For each set, female Sprague-Dawley rats were divided into four groups, to allow comparison among treated and non-treated groups. At 50 days of age, animals of group B and C were given DMBA injection (0.5 mg/100 g body weight) through the tail vein, and normal control (group A) animals received the oil emulsion vehicle alone. Vitamin D3 at the dose of 0.3 microgram/0.1 ml propylene glycol was given orally twice a week, in carcinogen as well as non-carcinogen treated animals (group C and c), until the termination of the experiments (22-24 weeks for biochemical markers, and 35 weeks for morphology). At approximately 22-24 weeks, when marked lobular hyperplasia in DMBA control groups were confirmed through histology, the biochemical markers were modulated towards normal value for vitamin D3 in the treatment group, in comparison to the disturbed values caused by carcinogen administration in group B animals. Again, vitamin D3 supplementation was effective in reducing the tumour incidence (70% in comparison to 90% in group B). The results thus clearly concluded the antineoplastic potential of vitamin D3, and the existing correlation between biological and biochemical markers.
9,10-Dimethyl-1,2-benzanthracene↗
Influence of cadmium intoxication on hepatic lipid peroxidation, glutathione level, and glutathione S-transferase and gamma-glutamyl transpeptidase activities: correlation with chromosome aberrations in bone marrow cells.
We examined whether there was any correlation between chromosome aberrations (CAs) in bone marrow cells with hepatic lipid peroxidation (LPO), reduced glutathione (GSH) level, glutathione S-transferase (GST), and gamma-glutamyl transpeptidase (GGT) activity after cadmium (Cd) intoxication in both a dose- and a time-dependent manner. Cadmium chloride was administered subcutaneously in doses of 0.5, 1.5, 2.5, and 5.0 mg/kg body weight to Swiss albino Balb/c male mice. The animals were exposed for 8, 16, and 24 days, i.e., 4, 8, and 12 doses, respectively. Biochemical parameters were measured in hepatic tissue for a correlation with chromosome aberrations in bone marrow. With the increment of dose and advancement of time points, the biochemical, as well as the cytogenetic, parameters altered significantly. Hepatic lipid peroxidation and GGT activity increased significantly along with an increased percentage of chromosome aberrations in the bone marrow, but the hepatic reduced glutathione level and GST activity were found to decrease following Cd administration. Up to 5.0 mg Cd/kg body weight, lipid peroxidation did not exhibit threshold levels of toxicity as shown by the two-way (fixed effect) analysis of variance test. In contrast, the observed values of reduced glutathione levels, GST and GGT activity, and chromosome aberrations in bone marrow showed threshold activity levels. Therefore, there might be a relationship between an increase in the frequency of chromosome aberrations, elevated lipid peroxidation, and depleted glutathione levels and GST and GGT activity. The clastogenic efficacy of Cd may be mediated through the biochemical pathways.
Animals↗
The effects of cadmium on the hepatic and renal levels of reduced glutathione, the activity of glutathione S-transferase and gamma glutamyl transpeptidase.
Cadmium chloride, injected subcutaneously in mice at doses of 1.0, 1.5, and 2.0 mg/Kg body weight, resulted in the alteration of body weight and relative liver and kidney weights, the hepatic and renal reduced glutathione levels, and the activity of the enzymes glutathione S-transferase and gamma-glutamyl transpeptidase in a dose-dependent manner. Body weight increased insignificantly with dosage, but significant elevations in relative liver weight (29% of control) and particularly in kidney weight (93% of control) were documented in the cases that received the highest dose of cadmium chloride (2.0 mg/Kg body weight). The treatment significantly lowered hepatic and renal reduced glutathione levels and glutathione S-transferase activity. On the other hand, the gamma-glutamyl transpeptidase activity was found to increase significantly after treatment, with the highest values in the liver (137% of control) and in the kidneys (204% of control). We found that cadmium chloride at 2.0 mg/Km body weight produced the greatest changes in the abovementioned parameters. A significant correlation (r) was observed in some cases among the abovementioned biomolecules between, as well as within, the organs. The present study showed that the effects of cadmium could be correlated with a decreased level of reduced glutathione and glutathione S-transferase activity and an increased activity of gamma-glutamyl transpeptidase in liver and kidney.
Animals↗
Cadmium-induced alterations of hepatic lipid peroxidation, glutathione S-transferase activity and reduced glutathione level and their possible correlation with chromosomal aberration in mice: a time course study.
Cadmium, a heavy metal, has been found to possess a potent toxic effect on liver and bone marrow. In the present study, attempts were made to understand whether or not any correlation existed between hepatic lipid peroxidation, glutathione S-transferase activity, reduced glutathione level and chromosome aberrations, micronucleus and mitotic index in bone marrow cells of Balb/C male mice. Cadmium chloride (2.5 mg/kg b.wt.), when administered subcutaneously for 7 alternate days, exerted duration-dependent toxic effects on hepatic biochemical and cytogenetic parameters of bone marrow. A shorter time interval (5 days) elicited no significant alteration in the case of biochemical parameters, but with the advancement of time (i.e. after 10 and 15 days) lipid peroxidation showed 102% (p < 0.001) elevation and after 15 days, glutathione S-transferase activity and reduced glutathione level decreased by 35%, (p < 0.001) and 32% (p < 0.001), respectively, from the control values with concomitant elevation of chromosomal aberrations (30%) and micronucleus (2.32%) but the mitotic index was inhibited by 1.26%. The results of our study, provided evidence of cadmium-induced duration-dependent depression of GSH-mediated GST-catalysed detoxication capacity of the host and that this was presumably related to the induction of chromosomal aberrations. The clastogenic efficacy of this heavy metal was thus evident from the study.
Animals↗
Antihepatotoxic potential of Trianthema portulacastrum in carbon tetrachloride-induced chronic hepatocellular injury in mice: reflection in haematological, histological and biochemical characteristics.
The effect of an ethanolic extract of the plant Trianthema portulacastrum L. on the CCl4-induced chronic hepatocellular damage of Swiss albino mice has been investigated. The normal mice received olive oil (0.2 ml/mouse) for five weeks. The CCl4 control mice, on the other hand, received CCl4 (0.05 ml/mouse) in olive oil for five weeks. The extract was administered at the dose of 100 mg/kg or 150 mg/kg for five weeks by gastric intubation in addition to CCl4 treatment. The CCl4 administration alone caused hepatocellular necrosis, severe anemia, leucopaenia, lymphocytopaenia, neutrophilia, eosinophilia and haemoglobinaemia along with the alterations of plasma albumin and globulin. The administration of plant extract (at 100 or 150 mg/kg) restored the CCl4-induced alterations of the haematological parameters to the normal level. The extract of T. portulacastrum elicited a marked protection against CCl4-induced hepatotoxicity as indicated by the several haematological parameters, related indices of formed elements, and different fractions of plasma protein. We also observed the dose-dependent antihepatotoxic effect of the extraction on these mice. The 150 mg/kg of extract was found to be more effective in normalizing the toxic effects of CCl4 on the above parameters of mice. These results suggest that the hepatoprotective effect of T. portulacastrum could be caused by its critical involvement in modulating several factors associated with erythropoiesis, and the boosting of general immunity of the host.
Animals↗
Vanadium toxicology--an assessment of general health, haematological aspects and energy response in an Indian catfish Clarias batrachus (Linn).
The pervasive occurrence of vanadium in nature and its use in various industrial processes has increased its inputs in the environment. This has prompted us to elucidate the impact of vanadium on aquatic environment, the primary body for industrial effluent discharge. The energy response of the fish, Clarias batrachus, its haematological status including haemoglobin (Hb), haematocrit (Ht), leutocrit (Lt), mean corpuscular haemoglobin (MCH), mean corpuscular volume (MCV), mean corpuscular haemoglobin concentration (MCHC) etc. And overall general health conditions have been observed to be significantly hampered leading to deleterious alterations in the general metabolism of the fish following long term exposure to vanadate. The increase in muscle and tissue lactic acid (2-12 fold) in association with decrease in pyruvic acid (72% in muscle; 26% in liver) reflect a shift towards an anaerobic metabolism of the fish. We conclude that vanadium could be toxic for the fish in question under long term exposure at the doses under observation (2-10 mg L-1).
Anaerobiosis↗
Prednisolone-induced alteration in hepatic and muscular protein and glycogen level: its correlation with blood glucose level in mice.
Prednisolone, a potent glucocorticoid, is well known for its immunosuppressive effects on animals. A single dose of 100 microg, 200 microg and 300 microg prednisolone/kg body weight was administered in Swiss albino male mice. Seven days after treatment, the animals were sacrificed to investigate the effect of prednisolone on hepatic and muscular protein contents and glycogen levels along with the level of blood glucose. A catabolic effect on the protein level was evidenced but at the same time the mice became hypoglycemic.
Animals↗
Vanadium-mediated chemoprotection against chemical hepatocarcinogenesis in rats: haematological and histological characteristics.
The trace element vanadium was investigated for its anti-neoplastic role in relation to haematological status, hepatic histopathology and histochemical analysis of glycogen in liver. Its impact on the survival of male Sprague-Dawley rats subjected to a two-stage hepatocarcinogenesis regimen was also assessed. Initiation was performed using a single intraperitoneal injection of diethylnitrosamine (DENA) (200 mg/kg) followed by promotion with phenobarbital (0.05%) in a basal diet. Vanadium supplementation as ammonium monovanadate at 0.5 ppm vanadium in drinking water was given ad libitum throughout the experiment (20 weeks), before the initiation (4 weeks), or during the promotional period (14 weeks). At the end of the study, there was a significant decrease in red blood cell count, haemoglobin content, haematocrit value, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, plasma volume change and total white cell count, with a concurrent alteration in lymphoid:myeloid ratio in DENA control animals compared with their normal counterparts. Vanadium supplementation throughout the study or before the initiation significantly reversed the DENA-induced alterations in most of the haematological indices. A single intraperitoneal injection of DENA also depleted the plasma albumin concentration, raised the plasma globulin content, and decreased the ratio of albumin to globulin. These altered features began to return to normal following vanadium supplementation. Supplementary vanadium also elicited substantial protection against DENA-mediated rat liver carcinogenesis. This was fairly evident from hepatic histology and evaluation of glycogen accumulation by periodic acid-Schiff reaction. The survival of DENA-treated animals was considerably increased in the presence of vanadium. The critical involvement of vanadium in modulating several factors associated with erythropoiesis under carcinogenic challenge may thus have a possible impact on the eventual increased survival of the host.
Administration, Oral↗
Variations in diurnal rhythm of leucocytes in white Leghorn chicks of two different ages.
Blood leucocytes in 4-week-old and 5-7-month-old White Leghorn cockerels show a diurnal rhythm. This diurnal rhythm has been observed to vary with age. The variations observed may be due to the different hormonal status of the two groups of birds. The effects of drugs at different phases of the diurnal rhythm will be of great interest in medical practice and should be considered during clinical treatment.
Age Factors↗
Some host factors and seasonal variations in the fatal road traffic accidents occurring in eastern suburban Calcutta.
An extensive study of road traffic accident cases occurring within eastern suburban Calcutta during April 1992 to March 1993 was done. Of which 276 fatal cases having minimum medical aids were taken into consideration to avoid erroneous interpretation. Male pedestrians of age group of 50 years and above were mostly involved during the time period of 5 A.M. to 12 Noon. Fatal Accidents mostly occurred during winter and on the broader roads (Highways) and in majority of cases victims were at fault.
Accidents, Traffic↗