PubMed Health⌕ Search

Biomedical subjects

R Bhadra

Publications and source records attributed to R Bhadra.

At least 37 records · Page 2Linked to original sources
PubMed1987

Lectin-binding assay by polyethylene glycol 8000.

A quantitative lectin-binding assay using a precipitation technique and polyethylene glycol 8000 (PEG) as a precipitating agent has been described. Carcinoscorpin, a sialic acid-binding lectin isolated from the hemolymph of Indian horseshoe crab, Carcinoscorpius rotunda cauda, and iodinated fetuin, a sialoglycoprotein, were appropriately incubated as the components of the binding assay. The specific interaction between these two components developed the lectin-glycoprotein-bound complex. This was subsequently precipitated by the addition of PEG together with a coprecipitant gamma-globulin. Radioactivity of the precipitated bound complex was estimated to quantify the binding. The formation of the bound complex was effectively inhibited by a specific sialodisaccharide, O-(N-acetylneuraminyl)-(2----6)-2-acetamido-2-deoxygalactitol, implying the specific interaction for such precipitation. The probable effect of PEG was to stabilize the bound complex, precipitating it along with added gamma-globulin. This was further evident from the prevention of dissociation of the bound complex and increased binding of glycoprotein to the immobilized lectin in the presence of PEG. The assay was also applicable to other sialoglycoproteins such as alpha 1-acid glycoprotein and human chorionic gonadotropin. Moreover, the method yielded a saturation plateau with a characteristic hyperbolic binding curve. The assay was simple, quick, safe, economic, and highly sensitive.

Drug Stability↗
PubMed1985

Effect of amines on fibrinogen synthesis.

L-Epinephrine, serotonin, and isoproterenol stimulate the incorporation of [14C]leucine into thrombin-induced clottable protein; this stimulation was abolished by actinomycin D. The incorporation of 32P into total RNA of rat liver, the site of fibrinogen synthesis, was stimulated by epinephrine and was highest at 2 h after 32P administration. [14C]Orotic acid incorporation into polysomal RNA of liver was also increased significantly by epinephrine and serotonin. The immunoprecipitation of newly synthesized protein by monospecific antibody raised against pure rat fibrinogen clearly demonstrates that L-epinephrine increased fibrinogen formation in vivo under the experimental condition. Translation of poly (A)-containing RNA from total polysomal RNA clearly indicates that L-epinephrine increased mRNA specific for fibrinogen.

Animals↗
PubMed1985

Bioassay of fish gonadotrophin by ovarian mitochondrial cholesterol depletion.

Murrel (Channa punctatus Bloch) ovarian tissues were incubated in vitro with or without piscine gonadotrophins and then subjected to subcellular fractionation followed by nonesterified cholesterol (cholesterol) assay. Gonadotrophin from salmon (SG-G100), tilapia (TL1MS), and sturgeon (S27MS) depleted cholesterol in the mitochondrial fraction, whereas cholesterol remained unchanged in other subcellular fractions. Aminoglutethimide, an inhibitor of mitochondrial cholesterol side-chain cleavage, blocked the depletion of mitochondrial cholesterol in response to SG-G100 and murrel pituitary extract. When ovarian tissue containing [4-14C]cholesterol was challenged with SG-G100 in vitro, a dose-dependent decrease of mitochondrial [4-14C]cholesterol was observed. Increasing concentrations (1, 2, 4, 6, or 8 micrograms/incubation) of SG-G100, TL1MS, and S27MS resulted in a clear linear depletion of mitochondrial cholesterol. The slope of the dose-response curve in different individual fish was found to be distinctly uniform and parallel. The slopes of the standard curves obtained with TL1MS and S27MS were greater than that with SG-G100, indicating that tilapia and sturgeon gonadotrophins are more potent. Carp pituitary gonadotrophin content, determined by using these standard curves, showed the sensitivity and precision of this bioassay.

Aminoglutethimide↗
PubMed1983

Effect of glucagon on alanine 2-oxoglutarate aminotransferase.

Alanine-2-oxoglutarate aminotransferase activity in mouse liver is stimulated by the intravenous injection of glucagon. The stimulation is abolished by pretreatment with actinomycin D indicating that the increased activity is probably due to new enzyme formation. Administration of dibutyryl cyclic AMP, isoproterenol, an activator of adenyl cyclase and theophylline, an inhibitor of phosphodiesterase also increases the enzyme activity suggesting the involvement of cyclic AMP in glucagon-mediated increase of enzyme activity.

Alanine Transaminase↗
PubMed1978

Biodegradative threonine dehydratase. Reduction of ferricyanide by an intermediate of the enzyme-catalyzed reaction.

The threonine-dependent reduction of ferricyanide catalyzed by the purified biodegradative threonine dehydratase of Escherichia coli has been studied. The rate of production of 2-oxobutyrate in the presence of ferricyanide was lower than that found in the absence of ferricyanide. The concentrations of threonine required for half-maximal effects for the reduction of ferricyanide and, in the presence of the dye, for 2-oxobutyrate production, were 3 mM and 9mM, respectively. Reduction of ferricyanide was accompanied by evolution of CO2, and even within a very short incubation time with the enzyme, the ratio of ferricyanide reduced over CO2 evolved was approximately 7. Stopping the enzyme activity after a brief exposure to threonine at pH 9.7 resulted in the accumulation of an intermediate (with a half-life of 4 min at 25 degrees C) which formed an adduct with N-ethylmaleimide; the accumulated intermediate, in the absence of N-ethylmaleimide, reduced ferricyanide with concomitant evolution of CO2. We conclude from these results that 2-aminocrotonate is the intermediate which serves as a source of reducing equivalent for ferricyanide, and nonstoichiometric amount of ferricyanide reduction may be attributed to some secondary reactions of ferricyanide with compounds derived from the oxidation product of 2-aminocrotonate.

Escherichia coli↗