Biomedical subjects

M Chatterjee

Publications and source records attributed to M Chatterjee.

At least 19 recordsLinked to original sources

PubMed1999

Diagnostic and prognostic potential of antibodies against O-acetylated sialic acids in canine visceral leishmaniasis.

Employing bovine submaxillary mucin (BSM) as the coating agent, an enzyme-linked immunosorbent assay (BSM-ELISA) was developed to detect antibodies directed against O-acetylated sialic acids (O-AcSA) in canine visceral leishmaniasis (CVL). Serum samples were collected from 50 dogs previously screened by a parasite-ELISA to detect anti-leishmanial antibodies and designated as seropositive (n = 30) and seronegative (n = 20). The BSM-ELISA detected anti-O-AcSA antibodies in 29 out of 30 seropositive dogs and was negative in 15 out of 20 seronegative dogs; the sensitivity and specificity of the assay being 96.6% and 75%, respectively. Seven dogs from an endemic area in central Israel were longitudinally monitored for 15 months clinically, serologically and cultured for parasite. The levels of antibodies directed against O-AcSA increased with the appearance of clinical symptoms and/or seropositivity, disappeared when the disease was self-limiting as also with chemotherapeutic response and reappeared with relapse. The BSM-ELISA, therefore, represents a valuable tool for assessment of disease progression.

Acetylation↗

PubMed1999

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↗

PubMed1999

Effects of stimulation mode on threshold and loudness growth in multielectrode cochlear implants.

The effect of increasing the separation between the two members of a stimulating electrode pair was studied in four users of the Nucleus-22 cochlear implant. Two experiments were performed. In experiment 1, detection threshold for a 200-ms, 500-pulses/s biphasic pulse train was measured as the spatial separation between the active and return electrodes was increased. In experiment 2, loudness-growth functions were measured as the electrode separation was increased. The results of experiment 1 indicate that (a) threshold decreases monotonically toward an asymptote (monopolar threshold) as the electrode separation is increased and (b) the threshold versus electrode separation function is similar across subjects and electrode location. The results of experiment 2 indicate that loudness L is related to the current amplitude I by a simple exponential function: L = e beta I, where beta, the exponent of the loudness function, is, to a first approximation, linearly related to the separation between the electrodes of the stimulating pair. Thus, dynamic range and the shape of loudness growth can be directly linked to the spatial separation between active and return electrodes.

Auditory Threshold↗

PubMed1999

Temporal mechanisms underlying recovery from forward masking in multielectrode-implant listeners.

This paper describes a detailed study of recovery from forward masking in six users of the Nucleus-22 cochlear implant with a range of performance in speech-recognition tests. Recovery from a 300-ms-long pulse train presented at 1000 pps was found to be fastest in the poorer performers. The shape of the recovery function was found to be most strongly influenced by masker duration, suggesting that temporal integration plays a prominent role in recovery from forward masking. The recovery functions are reasonably well described by a sum of two exponentially decaying processes. Their relative weights depend on the amount of temporal integration occurring during the masker, and show strong intersubject variability. Nonmonotonicities sometimes observed in the recovery functions may be accounted for by considering the influence of neural adaptation.

Adult↗

PubMed1999

Diagnostic and prognostic potential of a competitive enzyme-linked immunosorbent assay for leishmaniasis in India.

A Leishmania donovani species-specific monoclonal antibody (monoclonal antibody D2) was evaluated for its diagnostic and prognostic potential by a competitive enzyme-linked immunosorbent assay (C-ELISA) in sera from Indian patients with visceral leishmaniasis (VL) and seven patients with post-kala-azar dermal leishmaniasis (PKDL). These results were compared with those obtained by microscopy with Giemsa-stained tissue smears and a direct enzyme-linked immunosorbent assay (direct ELISA) with crude parasite antigen. Of 121 patients with clinically diagnosed VL examined, 103 (85.1%) were positive and 11 (9.1%) were negative by all three methods. An additional 7 (5.8%) who were negative by microscopy were positive by both C-ELISA and direct ELISA. Seven PKDL patients were also examined and were found to be positive by all three methods. Analysis of the chemotherapeutic response to sodium antimony gluconate of these 110 serologically positive VL patients showed that 57 (51.8%) were drug responsive and 53 (48.2%) were drug resistant. The C-ELISA with sera from 20 longitudinally monitored VL patients before and after chemotherapy showed a significant decrease in percent inhibition of monoclonal antibody D2 in drug-responsive patients. However, in drug-unresponsive patients, the percent inhibition of D2 was unchanged or was slightly increased. Our results therefore indicate (i) the applicability of L. donovani species-specific monoclonal antibody D2 for sensitive and specific serodiagnosis by C-ELISA, (ii) that the C-ELISA is more sensitive than microscopy, especially for early diagnosis, (iii) that L. donovani is still the main causative agent of VL, irrespective of the chemotherapeutic response, and (iv) that the C-ELISA can be used to evaluate the success of drug treatment.

Animals↗

PubMed1999

Characterization of selective induction and alteration of xenobiotic biotransforming enzymes by vanadium during diethylnitrosamine-induced chemical rat liver carcinogenesis.

Our recent studies have shown that vanadium, a dietary micronutrient, has an inhibitory response against experimentally induced rat liver carcinogenesis. In the present study, the effect of vanadium on hepatic xenobiotic biotransformation in rats exposed to diethylnitrosamine (DENA, 200 mg/kg, IP) was investigated to elucidate a possible mechanism of vanadium-mediated prevention of chemical carcinogenesis. Supplementary vanadium in drinking water at 0.5 parts per million (ppm) was employed ad lib before and after the intiation with DENA, before the initiation only, or during the promotional event. After 20 weeks, there was a significant reduction of hepatocyte nodules (HNs) (P<0.01), nodule multiplicity (P<0.001), and the number of nodules more than 3 mm in size in the long-term vanadium-supplemented rats than their DENA control counterparts. Total cytochrome P450 and b5 contents as well as cytochrome P450 2E1 (CYP2E1, EC 1.5.99), aryl hydrocarbon hydroxylase (AHH, EC 1.14.14.2), and UDP-glucuronyl transferase (UDPGT, EC 2.4.1.17) activities in the microsomal fractions of HNs and nonnodular surrounding parenchyma (NNSP) were found to be significantly decreased in DENA control group compared to untreated normal control. Though supplementary vanadium had little or no influence on the contents of cytochrome P450 and b5 and activities of CYP2E1 and AHH in HNs and NNSP, it substantially elevated the UDPGT activity in both HNs and NNSP liver areas. DENA treatment alone also brought about a sharp decrease in cytosolic UDP-glucose dehydrogenase (EC 1.1.1.22), DT-diaphorase (EC 1.6.99.2), and glutathione S-transferase (EC 2.5.1.18) activities in HNs and NNSP compared to normal liver. Supplementary vanadium was found to exert a marked induction in these cytosolic enzymes in HNs as well as NNSP when compared to DENA control. A positive correlation of phase I and phase II drug metabolizing enzymes in HNs or NNSP was always observed in DENA or DENA plus long-term vanadium-treated group. It is concluded that the chemoprotective effect of vanadium may be attributed to the substantial elevation of phase II conjugating enzymes, which may lead to a move and shift of the metabolic profile that may reduce the intracellular concentration of carcinogen-derived reactive intermediates.

Animals↗

PubMed1999

Inhibitory effect of Trianthema portulacastrum L. diethylnitroso-amine-induced phenobarbital promoted hepatocarcinogenesis.

The chloroform extract (active components from the exotic weed Trianthema portulacastrum L. of Aizoaceae, showed remarkable effect in the reduction of DENA-induced rat hepatocarcinogenesis. Hepatocarcinogenesis was induced in male Sprague-Dawley rats by a single intraperitonial injection of diethylnitrosoamine (DENA) at a dose of 200 mg/kg body weight. Chloroform extract of T. portulacastrum at a dose of 100 mg/kg/body wt. to the basal medium/per animal once daily was administered following DENA injection. Morphometric evaluation revealed that the fraction reduced the incidence, numerical preponderance, multiplicity and size distribution of visible pre-neoplastic nodules. Further focal lesions showed a reduction of altered liver cell foci/cm2 and a reduction of average focal area. A decrease in the percentage of liver parenchyma occupied by foci all seem to suggest the anticarcinogenic potential of Trianthema portulacastrum in DENA-induced rat hepatocarcinogenesis.

Animals↗

PubMed1999

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↗

PubMed1998

Expression and activity of p67 are induced during heat shock.

p67, a cellular glycoprotein, protects eIF2 alpha from phosphorylation by inhibitory kinases such as PKR and HCR. p67 promoter contains heat shock element (HSE). To investigate whether this HSE of p67 has any role during heat-shock, rat tumor hepatoma cells were transiently transfected with CAT reporters linked to p67 promoter with HSE and without HSE. Heat shock induced CAT activity when p67 promoter contained HSE and this induction was not observed when HSE was deleted from the p67 promoter. In response to heat-shock, the endogenous p67 mRNA was also induced to more than 36-fold, and much of it translated into protein which was modified by GlcNAc moieties. The time of induced glycosyl modification at the later stages of the heat-shock correlates with the reduced level of eIF2 alpha phosphorylation. During later stages of the heat shock of animal cells, there is a preferential translation of a small class of messages encoding heat shock proteins. Our results suggest that the expression and activity of p67 are induced at the later stages of the heat-shock, and may be involved in the preferential translation of the heat-shock messages.

Aminopeptidases↗

PubMed1998

Protective role of Trianthema portulacastrum against diethylnitrosoamine-induced experimental hepatocarcinogenesis.

The chemopreventive efficacy of the Indian medicinal plant Trianthema portulacastrum L. Aizoaceae was tested in a chemical rat hepatocarcinogenesis model in male Sprague-Dawley rats. Hepatocarcinogenesis was induced by the potent carcinogen diethylnitrosoamine (DENA). Treatment of the rats to the basal medium with aqueous, ethanolic and chloroform fractions of the plant extract at a dose of 100 mg/kg body weight once daily reduced the incidence, numerical preponderance, multiplicity and size distribution of visible neoplastic nodules. Morphometric evaluation of focal lesions showed a reduction of altered liver cell foci/cm2 and a reduction of the average focal area. A decrease in the percentage of liver parenchyma occupied by foci seems to suggest the anticarcinogenic potential of the plant extract in DENA-induced hepatocarcinogenesis.

Animals↗

PubMed1998

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↗

PubMed1998

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↗

PubMed1998

Cochlear mechanisms of frequency and intensity coding. II. Dynamic range and the code for loudness.

Our preceding paper described SPL-dependent changes in the shape of transfer functions recorded from inner and outer hair cells as well as supporting cells, in the 500-2500 Hz regions of the Mongolian gerbil cochlea. As SPL was increased, large shifts were observed in the peak of the transfer function. A strongly compressive nonlinearity was also observed at CF. This paper examines the data from the perspective of intensity coding in the auditory periphery. Based on the data, we offer a new explanation for the mechanisms underlying the different dynamic ranges of low and high threshold auditory neurons. We also find that, for pure tone stimuli, the growth of excitation at the characteristic place saturates rapidly, and cannot encode the wide dynamic range of loudness. The data are analyzed to explore other excitation pattern candidates for loudness coding. The growth of the peak of the IHC transfer function, as well as the growth of the response area, have been found to be linearly related to loudness growth over most of its dynamic range. Implications of the data for auditory intensity coding are discussed.

Animals↗

PubMed1998

Novel implications of the potential role of selenium on antioxidant status in streptozotocin-induced diabetic mice.

Levels of blood glucose, lipid peroxidation, glutathione (GSH), glutathione peroxidase (GPx), glutathione S-transferase (GST) activities and blood selenium levels were determined in streptozotocin (STZ)-induced diabetic mice. The effect of oral administration of sodium selenite was studied on the above parameters. Diabetes caused hyperglycemia (2.8-fold increase) with a significant increase in the malondialdehyde levels (89% in liver and 83% in blood) and GST activity (55%) and marked decreases in GSH levels (approximately 73% in blood and 79% in liver) in the 5th week after STZ treatment as compared to normal control animals. Treatment of STZ-induced diabetic mice with sodium selenite changed these parameters to near control values in almost all cases. These results suggest that selenium plays a role in reducing the oxidative stress associated with diabetes.

Animals↗

PubMed1998

Identification of antibodies directed against O-acetylated sialic acids in visceral leishmaniasis: its diagnostic and prognostic role.

A significantly increased O-acetylated sialic acid (O-AcSA) binding fraction was purified from serum of visceral leishmaniasis (VL) patients by affinity chromatography on immobilized bovine submaxillary mucin (BSM) and found to be immunoglobulin in origin. The serodiagnostic and prognostic potential of BSM as a capture antigen was established by ELISA with no cross reactivity with coendemic diseases like malaria, tuberculosis, leprosy, chagas disease and cutaneous leishmaniasis; however, a strong cross reactivity was present with trypanosomiasis patients. In 56 clinically diagnosed VL patients, the BSM-ELISA was compared with diagnosis by microscopy using Giemsa stained tissue smears and direct ELISA using crude parasite antigen (parasite-ELISA); 49/56(87.5%) and 5/56(9.0%) were positive and negative respectively by all 3 methods. The BSM-ELISA failed to diagnose 2/56(3.5%) patients which were biopsy and parasite-ELISA positive. The prognostic potential of the BSM-ELISA in 18 longitudinally monitored VL patients before and after conventional antimonial treatment showed a significant decrease in anti O-AcSA titres in drug responsive patients whereas anti O-AcSA levels persisted in drug unresponsive patients. The IgG subclass distribution of antibodies directed against O-AcSA showed increased IgG2 levels in VL patients as compared to healthy controls. The BSM-based ELISA holds great promise as a serodiagnostic and prognostic assay for VL.

Acetylation↗

PubMed1998

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↗

PubMed1998

Distribution of IgG subclasses in antimonial unresponsive Indian kala-azar patients.

Sodium antimony gluconate (SAG) is the mainstay of treatment for visceral leishmaniasis (VL) or kala-azar. In view of the increasing incidence of refractoriness to SAG in India, we compared the levels of parasite-specific IgG and IgG subclasses in 20 longitudinally followed up kala-azar patients. In both SAG-responsive (n = 10) and unresponsive patients (n = 10), the levels of total IgG, IgG1, IgG2, IgG3 and IgG4 were increased, the rank order being IgG1 > IgG2 > IgG3 = IgG4. Following treatment, a significant decrease in total IgG and the four subclasses occurred in the SAG-responsive group, whereas in the SAG-unresponsive group these levels were unchanged or slightly increased. Therefore, monitoring of IgG1 and IgG2 levels in Indian kala-azar patients is a good serologic alternative to monitoring the disease status.

Animals↗

PubMed1998

Accessing the tonotopic organization of the ventral cochlear nucleus by intranuclear microstimulation.

This study is part of a program to develop an auditory prosthesis for the profoundly deaf, based on multichannel microstimulation in the cochlear nucleus. The functionality of such a device is dependent on its ability to access the tonotopic axis of the human ventral cochlear nucleus in an orderly fashion. In these studies, we utilized the homologies between the human and feline ventral cochlear nuclei and the known tonotopic organization of the central nucleus of the inferior colliculus (IC). In anesthetized cats, stimuli were delivered to three or four locations along the dorsal-to-ventral axis of the posteroventral cochlear nucleus (PVCN), and for each stimulus location, we recorded the multiunit neuronal activity and the field potentials at 20 or more locations along the dorsolateral-ventromedial (tonotopic) axis of the IC. The current source-sink density (CSD), which delimits regions of neuronal activity, was computed from the sequence of field potentials recorded along this axis. The multiunit activity and the CSD analysis both showed that the tonotopic organization of the PVCN can be accessed in an orderly manner by intranuclear microstimulation in several regions of the PVCN, using the range of stimulus pulse amplitudes that have been shown in previous studies to be noninjurious during prolonged intranuclear microstimulation via chronically implanted microelectrodes. We discuss the applicability of these findings to the design of clinical auditory prostheses for implantation into the human cochlear nucleus.

Action Potentials↗