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Biomedical subjects

S Bala

Publications and source records attributed to S Bala.

63 records · Page 4Linked to original sources
PubMedDate not supplied

An improved method for the analysis of sennosides in Cassia angustifolia by high-performance liquid chromatography.

A reversed-phase column liquid chromatographic method for the analysis of sennosides A and B present in leaf and pod extracts of Cassia angustifolia has been developed using a Symmetry C18 column and a linear binary gradient profile. The method can be utilised for the quantitative determination of other sennosides as a baseline resolution for most of the constituents was achieved. The method is economical in terms of the time taken and the amount of solvent used (25 mL) for each analysis. The validity of the method with respect to analysis was confirmed by comparing the UV spectra of each peak with those of reference compounds using a photodiode array detector.

Anthraquinones↗
PubMedDate not supplied

Relevance of empirical optimization for cross-linking DNA by using an ordinary ultraviolet-light source.

For cross-linking DNA onto nitrocellulose or nylon membranes by using ordinary ultraviolet (UV) light, empirical optimization with respect to exposure time is crucial for obtaining complete hybridization signals. Longer than optimal UV exposure reduces the signal intensity particularly in the larger DNA fragments, whereas shorter exposure due to insufficient immobilization produces incomplete signals. Relevance of using ordinary source of UV light with respect to fixing DNA on a large number of circular filters during library screening is discussed.

Animals↗
PubMedDate not supplied

Divergent structure and function of the bicoid gene in Muscoidea fly species.

We have investigated the evolution of the bicoid (bcd) gene in fly species of the Muscoidea Superfamily. We obtained the complete bcd sequence from the housefly Musca domestica and found polymorphism in the coding region among Musca strains. In addition to Musca, we cloned most of the bcd coding sequences from two blowfly species Calliphora vicina and Lucilia sericata. The 5' and 3' regulatory regions flanking the Musca bcd gene are widely diverged in sequence from Drosophila; however, some important sequence motifs identified in Drosophila bcd are present. The predicted RNA secondary structures of the 3' UTRs are similar, despite sequence divergence. Comparison of Bicoid (Bcd) proteins shows a serine-rich domain of unknown function is present in the Muscoidea species, but is absent in other species. The in vivo function of bcd in Musca was tested by RNAi to mimic loss of function phenotype. We obtained a head defect phenotype similar to weak bcd alleles of Drosophila. Although our comparisons initially suggest functional conservation between species, closer inspection reveals significant differences. Divergence of structural motifs, such as regulatory elements in flanking regions and conservation of protein domains in some species but not in others, points to functional divergence between species. We suggest that the larger embryonic size in Muscoidea species restricts the morphogenetic activity of a weak Bcd activator, which has evolved a more specialized role in head determination and lost some functions in thoracic development.

3' Untranslated Regions↗
PubMedDate not supplied

Effect of glucagon on arrhythmias induced by coronary artery occlusion and ouabain in dogs.

The effect of glucagon in arrhythmias induced by coronary artery occlusion and ouabain was studied in dogs. Intravenous administration of glucagon (50 microgram/kg) to 6 dogs with more than 70% ectopic activity after coronary artery occlusion, resulted in significant (P less than 0.01) decrease in ectopics and increase in heart rate. Infusion of glucagon (2.5 microgram/kg/min) for 30 min caused complete elimination of ectopic activity during infusion period. In another series of 7 experiments, glucagon failed to abolish the ouabain-induced ectopic beats. In fact the hormone itself caused a significant (P less tha 0.01) increase in ectopic activity and heart rate. However, in 7 dogs with complete heart block produced after ouabain conversion to normal sinus rhythm was observed after glucagon.

Animals↗
PubMedDate not supplied

Effect of glucagon on the perfused rat hind-quarter vessles and on perfused coronary arteries of rabbit.

In rat hind-quarter perfusion experiments, glucagon (1 microgram) produced a significant vasodilation. On the other hand, in experiments with isolated perfused rabbit heart, glucagon (1 microgram) caused coronary vasoconstriction irrespective of whether noradrenaline was added to perfusion fluid or not. Glucagon had no effect on rate or force of contraction of heart.

Animals↗