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Biomedical subjects

R Biswas

Publications and source records attributed to R Biswas.

At least 55 records · Page 3Linked to original sources
PubMed1996

Aetiology of acute diarrhoea in hospitalized children in Hong Kong.

To determine the role of enteric pathogens in acute childhood diarrhoea in Hong Kong, 388 children with diarrhoea and 306 children of similar age without diarrhoea were evaluated in a hospital-based study during a one-year period from August 1994 to July 1995. Of the diarrhoeal cases, 55% were under 1 year and 95% were below 5 years of age. On admission, 22% had some dehydration but none was severely dehydrated. All children were well nourished. Oyer 60% of children with diarrhoea had one or more pathogens in their stool. Rotavirus was the most commonly isolated pathogen (34.6%), followed by Salmonella (23.3%), Campylobacter (4.7%) and Shigella (2.1%). Rotavirus was not assessed in the controls and was detected mainly during the winter months December to February. Bacterial pathogens were identified more commonly in diarrhoea patients (30%) than in controls (5.6%) (P < 0.001). Despite rapid recent socioeconomic development in Hong Kong, non-typhoidal Salmonella diarrhoea remains a significant local problem in infants under 1 year. Further detailed assessment of the transmission and prevention of this infection is required.

Acute Disease↗
PubMed1996

Molecular epidemiology of Escherichia coli diarrhea in children in Hong Kong.

This pediatric hospital-based study of 388 diarrhea cases and 306 controls analyzed predominant E. coli colonies from primary culture (253 cases and 177 controls) with eight DNA probes for enteropathogenic, enterotoxigenic, enteroaggregative, and diffusely adherent E. coli. Only enteropathogenic E. coli adherence factor was identified significantly more frequently in cases (10) than in controls (0).

Adolescent↗
PubMed1995

Gonadotropin releasing hormone stimulation of cyclic 3',5'-AMP in the pituitary cell of a teleost (Channa punctatus, Bloch) requires extracellular calcium: its relationship to gonadotropin release.

Pituitary cells were prepared by enzymatic dispersion and incubated in vitro. To observe the effect of gonadotropin releasing hormone (GnRH) and Ca2+ on the murrel pituitary cyclic 3',5'-AMP (cAMP), cells were dispersed by 0.3% collagenase plus 0.05% trypsin in Earle's minimum essential medium without Ca2+ and a considerably high yield of viable cells were obtained. Addition of a murrel, Channa punctatus, GnRH (cGnRH, 10 micrograms/incubation) to pituitary cell incubation (6 x 10(4) cells/well) containing 4 mM theophylline, a phosphodiesterase (PDE) inhibitor, stimulated cAMP accumulation in the pituitary cell 2.4-fold and its release into the medium about 2-fold as compared to control. The extent of stimulation was greatly increased on addition of Ca2+ (2 mM/incubation) with cGnRH: accumulation 5.8-fold and release 3.7-fold, respectively, in comparison to control. A time-course study with cGnRH (20 micrograms/incubation) plus Ca2+ (2 mM/incubation) on pituitary cell cAMP accumulation showed that the peak of cAMP level was reached at 15 min and remained at the same level until 60 min in the presence of theophylline; this peak was drastically reduced (5-fold) at 30 min in the absence of theophylline, indicating rapid hydrolysis of cAMP by PDE. Ca(2+)-augmented cGnRH stimulatory effect on cAMP accumulation and release could be significantly (P < 0.01) inhibited by verapamil (3 microM/incubation), a specific calcium channel blocker, suggesting requirement of extracellular Ca2+ influx in this process. Calmodulin (CaM), a Ca2+ carrier protein, addition to cGnRH and Ca2+ incubation further augmented the increase of cellular accumulation of cAMP and its release by 39.5 and 45%, respectively, in comparison to cGnRH and Ca2+ (both were statistically significant, P < 0.01). CaM effect could be blocked by calmidazolium (1 microM/incubation), a specific inhibitor of CaM, indicating specificity of the stimulatory action of CaM. Addition of radioiodinated 125I-CaM, in the presence of Ca2+ or cGnRH plus Ca2+ resulted in the binding of 125I-CaM to pituitary cells and to the pellet of the lysed cells. 125I-CaM specifically binds to pituitary cell plasma membrane preparation and saturation of 125I-CaM binding occurred at 9 ng of 125I-CaM. To investigate whether cGnRH plus Ca(2+)-stimulation of pituitary cells cAMP is linked to gonadotropin (GtH) release, similar protocols were followed. It was found that GtH release was augmented to 7-fold by cGnRH plus Ca2+, which was inhibited by verapamil and stimulated by CaM in a similar manner as observed in the case of cAMP.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

Simultaneous amplification and detection of specific hepatitis B virus and hepatitis C virus genomic sequences in serum samples.

A sensitive and specific two-stage polymerase chain reaction (PCR) technique was developed for the simultaneous amplification and detection of specific genomic sequences of hepatitis B virus (HBV) and hepatitis C virus (HCV) in serum samples. Initially, HCV-RNA was reverse transcribed to cDNA. This cDNA and DNA from HBV were then co-amplified using primer pairs derived from conserved regions of HBV and HCV nucleotide sequences. The specificity of PCR products was confirmed by liquid hybridization analysis using 32P end-labeled oligomer probes specific for the target HBV and HCV nucleotide sequences. Independent human serum samples, positive and negative by PCR for both HBV-DNA and HCV-RNA, were used as controls. We tested sera from nine donors, of which seven were reactive for HBsAg, anti-HBc, and anti-HCV (multiantigen test), one of whom was reactive for anti-HCV and anti-HBc, and one of whom was reactive for HBsAg and anti-HBc. The assay detected HBV- and HCV-specific genomic sequences in eight of eight sera reactive for both HBV and HCV serological markers and also in the serum that was reactive for HBV markers only.

Base Sequence↗
PubMed1994

High levels of viral replication during acute hepatitis B infection predict progression to chronicity.

To assess the pattern of development of serologic markers during acute hepatitis B, levels of HBsAg, HBeAg, and hepatitis B virus (HBV) DNA were assayed in stored serum samples obtained sequentially from 12 subjects infected with HBV during experimental studies conducted in the 1950s. Six patients developed acute self-limited hepatitis, three developed chronic hepatitis, and three had an asymptomatic infection without HBsAg. HBsAg was the first serologic marker detected (mean = 52 days after exposure), followed by HBeAg (62 days) and HBV DNA (72 days). Peak HBsAg levels occurred before onset of symptoms and correlated with peak titers of HBeAg and HBV DNA. Patients who developed chronic hepatitis had higher peak levels of viral markers than those with self-limited disease: HBsAg (30 versus 5.4 micrograms/ml), HBeAg (1:2,000 versus 1:60 titer) and HBV DNA (3,192 versus 444 pg/ml). Thus, chronic HBV infection is characterized by high levels of viral replication appearing early during the acute phase of infection.

Acute Disease↗
PubMed1994

Effect of vitamin A supplementation on diarrhoea and acute respiratory tract infection in children. A double blind placebo controlled trial in a Calcutta slum community.

To determine the effect of a massive single oral dose of vitamin A (200,000 IU) supplementation on diarrhoea and acute respiratory infection (ARI), a double-blind placebo controlled trial involving 174 children under six years of age (excluding infants) was carried out in a Calcutta slum community. Ninety-one children received vitamin A supplementation (experimental group) and 83 children received a placebo (control group). All the children were followed up for six months by active fortnightly surveillance for occurrence of diarrhoea or ARI and their duration. There was no statistically significant difference in the incidence of diarrhoeal episodes or ARI. However, there was a significant difference (p < 0.05) in the average duration of diarrhoea per episode (2.1 vs. 3 days) between the experimental and control groups. Possible beneficial effects of a single oral dose of vitamin A supplementation on the incidence of diarrhoea and ARI could not be demonstrated in the present study.

Acute Disease↗
PubMed1994

Effect of thyroidectomy, and thyroxine and alpha 2u-globulin replacement therapy on testicular steroidogenic and gametogenic activities in rats.

Adult male rats were thyroidectomized and killed after 22 days of treatment. Thyroidectomy lowered the weights of testes and accessory sex organs, decreased the activities of testicular delta 5-3 beta- and 17 beta-hydroxysteroid dehydrogenases (HSD), and diminished spermatogenesis, serum levels of testosterone and alpha 2u-globulin. Supplementation with thyroxine at a dose of 5 micrograms/100 g body weight per day for 21 days or supplementation with alpha 2u-globulin at a dose of 1.5 mg/rat per day for 21 days in thyroidectomized animals partially reversed the decrease in HSD activities and serum concentrations of testosterone and alpha 2u-globulin, while spermatogenesis was restored to normal. The weights of testes and accessory sex organs were also reinstated after supplementation with thyroxine or alpha 2u-globulin in thyroidectomized rats in comparison with thyroidectomized animals. It was concluded that alpha 2u-globulin may be an intermediary in the thyroid hormone control of testicular function.

17-Hydroxysteroid Dehydrogenases↗