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Biomedical subjects

S Biswas

Publications and source records attributed to S Biswas.

At least 181 records · Page 10Linked to original sources
PubMed1991

Substance P and substance K in the rat hypothalamus following monosodium glutamate lesions of the arcuate nucleus.

Adult rats treated neonatally with monosodium glutamate (MSG) exhibit lesions in the arcuate nucleus of the hypothalamus. Following MSG lesioning, dopamine content in median eminence/arcuate nucleus (ME/AN) tissue extracts declined by 60-70%. Substance P (SP) content as determined by radioimmunoassay was significantly decreased in the paraventricular nucleus (PVN) (531 +/- 30 pg, mean +/- SEM) compared to controls (871 +/- 110 pg) but was unchanged in ME/AN extracts. Substance K (SK) content decreased to 257 +/- 20 pg in the PVN of lesioned animals compared to controls (367 +/- 31 pg) and the ME/AN content of SK was also significantly decreased (236 +/- 36 pg compared to control levels of 619 +/- 65 pg). The CRF-41 content of the PVN and ME/AN was unchanged by MSG lesioning, indicating that these areas are not affected by MSG. The partial depletion of SP and SK in the PVN following MSG treatment provides evidence that at least some of the neurokinin content of the PVN may originate in cell bodies of the arcuate nucleus. However, the lack of response of ME/AN SP to MSG treatment may suggest that the arcuate nucleus is not the major source of SP in the median eminence.

Animals↗
PubMed1991

Human response to a malaria vaccine candidate antigen.

The Plasmodium falciparum heat-shock protein 70 (PFHSP70) has been proposed as a potential candidate antigen for a malaria vaccine. In this study the human immune response to this antigen has been evaluated. Enzyme-linked immunosorbent assays (ELISA) were performed on serum samples collected from individuals during and after malarial infection. Only 70% of falciparum malaria patients responded to this antigen during the natural course of infection and 54% of the recovered cases who had no parasitaemia at the time of blood collection lacked detectable antibody. The non-responders to PFHSP70 exhibited an antibody response to total schizont antigens. There was no correlation between the response against total schizont antigens and PFHSP70 antigen. The non-responsiveness against PFHSP70 was not related to age, sex or regional variations. These qualities are undesirable for a vaccine candidate antigen.

Adolescent↗
PubMed1991

Lower environmental temperature: effect of long-term exposure on diazepam-induced changes in brain GABA.

Long-term diazepam (DZ) treatment (5 mg/kg, i.p. for 15-30 consecutive days) reduced GABAergic activity in hypothalamus and cerebellum with the alteration of GABA synthesis and its release process. This long-term DZ-induced inhibition in GABAergic activity in hypothalamus and cerebellum was not altered when DZ-treated rats were exposed (2 h/day) to lower environmental temperature (LET; 12 degrees C) for 7-30 consecutive days. Although repeated exposure to LET did not affect the GABA system in cerebellum and hypothalamus, striatal GABAergic activity was significantly enhanced under similar conditions. This LET-induced (repeated exposure) stimulation in striatal GABAergic activity was prevented when rats were treated with DZ along with repeated LET exposure (2 h/day) under long-term conditions.

Animals↗
PubMed1991

Antimalarial effect of cyclosporin-A on murine P. berghei and human P. falciparum.

The effects of Cyclosporin-A (CsA) on the growth of Plasmodia were investigated in an experimental murine model in vivo and on human malaria in vitro. Mice were inoculated with Plasmodium berghei and then treated with different doses of CsA at the patent period. The development and course of this normally lethal parasitaemia in mice was affected by treatment with CsA which is a known immunosuppressant. The drug showed complete protection at a dose of 20 mg/kg wt/day without any recrudescence. Antibody level was at the detection limit after first bout of drug-cured infection. CsA was found to be an inhibitor of P. falciparum growth in a dose dependent fashion, as the concentrations of drug in culture medium increased, a significant reduction in parasitaemia was observed.

Animals↗
PubMed1990

A novel tubulin from Mimosa pudica. Purification and characterization.

From Mimosa pudica fresh leaves and pulvinar callus cells, we have purified tubulin protein using an anion-exchange resin, DEAE-Sephadex A-50, followed by ammonium sulfate fractionation and Sephadex G-200 gel filtration. The purified protein consisted of alpha and beta subunits and trace quantities of other proteins. When analysed by sodium dodecyl sulfate/polyacrylamide gel electrophoresis at pH 8.8, both alpha and beta subunits of tubulin almost comigrated with their counterparts from goat brain. Two-dimensional electrophoresis revealed that this tubulin contains one major alpha-tubulin having a pI value of 7.1 and three beta species having pI values of 6.70, 6.46 and 6.40. Morphologically normal microtubules were observed by electron microscopy; self-polymerization in vitro, even in the cold, can also be achieved. Radioimmunoassays, and also immunoblotting with the antibodies raised against alpha- and beta-tubulins of this plant, showed that the nature of alpha-tubulin is different from that obtained from other sources. This is an example of plant tubulin where strong colchicine binding at 1 microM was observed. This protein constitutes 5-6% of the total extractable protein in the leaves. We propose that movement of the leaves of this plant may be regulated by the presence of a high amount of this protein.

Blotting, Western↗
PubMed1990

Effect of short- and long-term exposure to low environmental temperature on brain regional GABA metabolism.

Single exposure of adult male rats to low environmental temperature (LET, 12 +/- 0.5 degrees C) for 2 h significantly increased the hypothalamic and striatal GABA levels without affecting those in other regions of brain. The activity of glutamate decarboxylase (GAD) was elevated in hypothalamus (H) and corpus striatum (CS) under these conditions. GABA accumulation rate (measured with ethanolamine-O-sulfate, an inhibitor of GABA-transaminase) was also increased in both H and CS of rats exposed to LET for 2 h. Unlike after a single exposure, the repeated exposure (2 h/day) for 7, 15, and 30 consecutive days did not change the hypothalamic GABA metabolism. No change in GABA metabolism was observed in CS when rats were repeatedly exposed to LET for 7 consecutive days. Prolongation of repeated exposure to LET (2 h/day) for 15 and 30 consecutive days decreased the striatal GABA level and increased the activity of GABA-transaminase, although GAD activity was not altered under these conditions. These results suggest that single exposure to LET accelerates GABA synthesis and may reduce the GABAergic activity in both H and CS; whereas repeated exposure to LET for 15 or 30 consecutive days enhances GABAergic activity with the stimulation of GABA utilization only in CS without affecting its synthesizing process. Thus, it may be suggested that the hypothalamic and striatal GABA system may play a characteristic role in response to short- and long-term exposure to LET.

4-Aminobutyrate Transaminase↗
PubMed1990

Ethnic differences in self poisoning: a comparative study between an Asian and white adolescent group.

A preliminary retrospective case note study is presented comparing various characteristics of self poisoning between a White and an Asian group of adolescents. A group of 38 Asian and 34 White adolescents of ages 17 years and below, was studied. The results showed that the sex ratio of both samples was similar. Also, "Culture Conflict" was implicated in slightly more of the Asian female self poisoning as compared to the males. Asian females used "non ingestants" significantly more than their White counterparts, and significantly more described their overdose as "accidental". Significantly more White females were in care at the time of the overdose.

Adolescent↗
PubMed1990

Natural killer activity against human K562 tumour cells during Plasmodium cynomolgi malarial infection of rhesus monkeys.

This study assessed the natural killer (NK) cell activity profile during Plasmodium cynomolgi infection in rhesus monkeys. There was a significant decrease in the NK cell activity in the peripheral blood leukocytes of infected monkeys during the early, ascending phase of infection. However, as the parasite load decreased, NK cell activity returned to normal levels. This could be correlated with the peak increase in lymphocyte counts. This indicated that a decrease in NK cell activity observed at an earlier stage during an active P. vivax malarial infection was a temporary phenomenon.

Animals↗
PubMed1990

Coexistence of nerve conduction deficit with increased Na(+)-K(+)-ATPase activity in galactose-fed mice. Implications for polyol pathway and diabetic neuropathy.

We measured motor nerve conduction velocity (MNCV), Na(+)-K(+)-ATPase activity, polyol-pathway metabolites, and myo-inositol in sciatic nerves from control mice, galactose-fed (20% wt/wt diet) mice, and galactose-fed mice given the aldose reductase inhibitor ponalrestat (300-mg/kg diet). Treatments were maintained for 4 wk. Galactose feeding was associated with a 21.5% reduction in MNCV (P less than 0.001), which was almost completely prevented by ponalrestat. Galactose-fed mice showed an 81% increase in Na(+)-K(+)-ATPase (P less than 0.01), an effect completely prevented by aldose reductase inhibition. Treatment of a separate galactose-fed group with sorbinil (300 mg/kg diet) also attenuated the MNCV deficit and prevented the increased Na(+)-K(+)-ATPase activity associated with galactosemia. Accumulation of galactitol in the nerves of galactose-fed mice was prevented by aldose reductase inhibition, but there were no alterations in myo-inositol levels in the sciatic nerves of any group. These data show that exaggerated flux through the polyol pathway can cause an MNCV deficit that is unrelated to either myo-inositol levels or NA(+)-K(+)-ATPase activity.

Aldehyde Reductase↗
PubMed1990

Does GABA act through dopaminergic/cholinergic interaction in the regulation of higher environmental temperature-induced change in body temperature?

Acute exposure of adult male albino rats to higher ambient temperature (40 degrees C) for 2 h significantly increased body temperature (BT). Administration of either bicuculline (1 mg/kg, i.p.), a GABA antagonist, or physostigmine (0.1 mg/kg, i.p.), an inhibitor of acetylcholinesterase, significantly increased BT of normal and heat-exposed rats. Treatment with muscimol (1 mg/kg, i.p.), a GABA agonist, produced hypothermia in normal rats and prevented an increase in BT of heat-exposed rats. The dopamine agonist, L-dopa (100 mg/kg, p.o.) along with carbidopa (10 mg/kg, p.o.) reduced BT of normal rats. Further, the bicuculline-or physostigmine-induced enhancement of BT in normal and heat-exposed rats was potentiated when both drugs were administered concomitantly. But this potentiating effect remained unaltered when dopamine antagonist haloperidol (1 mg/kg, i.p.) was administered along with bicuculline and physostigmine. Treatment with atropine (5 mg/kg, i.p.), a cholinergic antagonist, abolished the hyperthermic effect of bicuculline but potentiated the hypothermic effect of muscimol either at 28 degrees C or at 40 degrees C. Bicuculline-induced hyperthermia was attenuated at normal or higher temperature by pretreatment with L-dopa + carbidopa. The administration of L-dopa + carbidopa either abolished or reduced the hyperthermic effect of physostigmine at room temperature or at higher ambient temperature. These results suggest that (a) GABAergic, cholinergic and dopaminergic systems are involved in thermoregulation, (b) exposure to high environmental temperature may inhibit central GABAergic activity which activates the cholinergic system without affecting the dopaminergic system and raises BT, (c) central dopaminergic and GABAergic systems act independently through the modulation of cholinergic activity in the regulation of BT under normal ambient temperature.

Animals↗
PubMed1990

The natural occurrence of circulating antibodies in populations of endemic malarious areas.

The magnitude of humoral response to soluble antigen extracted from Plasmodium falciparum schizonts and merozoites was assessed in 744 blood samples collected from different parts of India. In this study, parasitological and immunological data were considered for assessment of antibody during natural infections at various seasons. The antibody response has been measured by enzyme-immuno assay. Survey was done in all age groups. Overall antimalarial IgG level had started increasing after five years which shows that the rate of infection was high in the small age groups. Elevated level of IgG in populations indicates that the study area is undergoing a period prevalence of the disease. In most of the individuals with active infection, IgG and IgM levels were high. Positivity in IgM denoted the active transmission of malaria. Elevated levels of antigen specific IgA was observed in some cases but the mechanism is not yet understood. Presence of circulating immune complexes during acute infection shows the failure of detection of circulating free antibodies in some individuals. The significance of findings in relation to serological status in individuals exposed naturally to malaria has been discussed.

Animals↗
PubMed1989

Method of stochastic prediction of population estimates based on Kendall's birth and death process.

"An attempt has been made to incorporate density and time-dependent birth and death rates into the generalized birth and death process given by Kendall (1948). The probability generating function of the process has also been investigated. A simple method of estimating the parameters of the process has been illustrated in the text. The applicability of the method for predicting the population of India, starting from the several deterministic projection figures given for any base year, is also discussed in the text."

Asia↗
PubMed1988

Differential effects of hypothalamic catecholamine depletion on the release of arginine vasopressin and CRF-41 into hypothalamo-hypophyseal portal blood.

The effects of 6-hydroxydopamine lesions of the ventral noradrenergic bundle (VNAB) and of intracerebroventricular 6-hydroxydopamine on hypothalamo-hypophyseal portal blood (HPB) concentrations of arginine vasopressin (AVP), corticotrophin releasing factor (CRF-41), and noradrenaline have been investigated. VNAB lesions and intracerebroventricular 6-hydroxydopamine caused a reduction of HPB CRF-41 concentration, while AVP remained unchanged. HPB noradrenaline concentration was reduced in animals treated with lateral ventricular 6-hydroxydopamine, but was unchanged in VNAB lesioned animals. Our results suggest differential effects of noradrenaline on the release of AVP and CRF-41 into HPB.

Adrenergic Fibers↗
PubMed1988

Hypothalamo-hypophyseal portal blood sampling from laboratory rats. The effects of endocrine manipulations on portal blood catecholamine concentrations.

We have obtained hypothalamo-hypophyseal portal blood using a modified Worthington-Fink technique, and measured the concentrations of catecholamines with a high pressure liquid chromatography - electrochemical detection system. The concentrations of noradrenaline, adrenaline and dopamine have been measured in portal blood after various endocrine manipulations, including adrenalectomy, orchidectomy and chemically induced hypothyroidism. After the induction of hypothyroidism, dopamine concentrations in portal blood increased. After orchidectomy, there was an increase in portal adrenaline concentration, though noradrenaline and dopamine were unchanged.

Adrenalectomy↗