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Biomedical subjects

G S Kumar

Publications and source records attributed to G S Kumar.

48 records · Page 3Linked to original sources
PubMed1991

Circular dichroism studies of the structure of DNA complex with berberine.

The binding of the benzodioxolo-benzoquinolizine alkaloid, berberine chloride to natural and synthetic DNAs has been studied by intrinsic and extrinsic circular dichroic measurements. Binding of berberine causes changes in the circular dichroism spectrum of DNA as shown by the increase of molar ellipticity of the 270nm band, but with very little change of the 240nm band. The molar ellipticity at the saturation depends strongly on the base composition of DNA and also on salt concentration, but always larger for the AT rich DNA than the GC rich DNA. The features in the circular dichroic spectral changes of berberine-synthetic DNA complexes were similar to that of native DNA, but depends on the sequence of base pairs. On binding to DNA and polynucleotides, the alkaloid becomes optically active. The extrinsic circular dichroism developed in the visible absorption region (300-500nm) for the berberine-DNA complexes shows two broad spectral bands in the regions 425-440nm and 340-360nm with the maximum varying depending on base composition and sequence of DNA. While the 425nm band shows less variation on the binding ratio, the 360nm band is remarkably dependent on the DNA/alkaloid ratio. The generation of the alkaloid associated extrinsic circular dichroic bands is not dependent on the base composition or sequence of base pairs, but the nature and magnitude of the bands are very much dependent on these two factors and also on the salt concentration. The interpretation of the results with respect to the modes of the alkaloid binding to DNA are presented.

Animals↗
PubMed1990

Persistent buccopharyngeal membrane with cleft palate. A case report.

A case of persistent buccopharyngeal membrane associated with cleft palate is reported. Persistence of the buccopharyngeal membrane results in partial fusion of the jaws and inability in opening and should be labeled as partial syngnathia. An association of this condition with cleft palate occurs as a part of the aglossia-adactylia and the popliteal pterygium syndromes. Though infrequently reported in the literature, presence of a persistent buccopharyngeal membrane associated with only cleft palate, without the other characteristics of the syndromes, does occur and should be recognized as a separate developmental defect.

Adolescent↗
PubMed1990

Training of primary health care medical officers in mental health care. Errors in clinical judgment before and after training.

This investigation examined the nature and frequency of errors in clinical judgment that were displayed by primary health care medical officers before and after short-term training in mental health care. Thirty-nine medical officers who underwent inservice training for 2 weeks were evaluated using standardized case vignettes. Before the training, doctors displayed a sizable percentage of major and minor errors, which dropped significantly following training. Errors were not unique to psychiatric presentations alone, but occurred with respect to vignettes representing physical disorders as well. The results on the whole demonstrate a satisfactory gain in clinical skills of medical officers following the training and highlight the need for continuation of a program of this nature.

Adult↗
PubMed1989

Interaction of berberine chloride with deoxyribonucleic acids: evidence for base and sequence specificity.

The interaction of berberine chloride with natural and synthetic DNAs of differing base composition and sequences was followed by various spectroscopic and viscometric studies. The binding of berberine chloride was characterized by hypochromism and bathochromism in the absorption bands, enhancement of fluorescence intensity, stabilization against thermal denaturation, perturbations in the circular dichroic spectrum, increase in the contour length of sonicated rod-like DNA and induction of unwinding-rewinding process of covalently closed superhelical DNA, depending on the base composition and sequences of base pairs. Binding parameters determined from absorbance and fluorescence titration by Scatchard analysis, according to an excluded-site model, indicated a very high specificity of berberine to AT-rich DNAs and alternate AT polymer. Fluorescence quantum yield was maximum for the complexes with AT-rich DNAs and alternate AT polymer. Taken together, these results suggest that berberine chloride exhibits considerable specificity towards alternating AT polymer and binds to AT-rich DNAs by a mechanism of classical intercalation.

Berberine↗
PubMed1988

Vasopressin: a model for the study of effects of additives on the oral and rectal administration of peptide drugs.

We previously observed, using a relatively primitive assay, that small oral doses (on the order of 1 microgram = 1 nmol = 1000 pmol per rat) of vasopressin can produce antidiuresis in hydrated rats, and that the oral activity was enhanced by simultaneous administration of an inhibitor of intestinal proteolysis. A more sensitive semi-automated computer-linked apparatus was used to conveniently and quickly compare the antidiuretic activities of the two natural and one synthetic vasopressin peptides by several routes of administration. (The approximate dose in pmol that resulted in a 50% decrease in urine flow is indicated in square brackets.) Intravenous lysine vasopressin was used as the benchmark dose [5]. Arginine and lysine vasopressin [3500], and the synthetic analogue, 1-deamino-8-D-arginine vasopressin (DDAVP) [20], were active by oral administration. The oral activities of arginine and lysine vasopressin were always enhanced by the simultaneous administration of aprotinin [1000], a natural inhibitor of trypsin; the effect of aprotinin on the oral activity of DDAVP was inconsistent. The vasopressins were more active when administered by the rectum: arginine vasopressin [20] and DDAVP [10]. The rectal activities of the peptides were increased by the absorption adjuvant, 5-methoxysalicylate (arginine vasopressin [10]; DDAVP [0.5]). The vasopressin peptides were also delivered by mouth in an impermeable coating of an azoaromatic cross-linked polymer, which is degraded by bacteria in the colon, to release the peptides in the upper colon for absorption (lysine vasopressin [525]).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1987

Diffusion-in-gel enzyme-linked immunosorbent assay, ELISA and IFA test in the detection of malarial antibodies.

Malarial antibodies in 80 patients were measured using the diffusion-in-gel enzyme linked immunosorbent assay (DIG-ELISA), enzyme-linked immunosorbent assay (ELISA) and the indirect fluorescent antibody (IFA) test. Good correlations were obtained between all three tests in terms of sensitivity and reliability. DIG-ELISA has the advantage of being a rapid diagnostic tool for the detection of malarial antibodies.

Animals↗
PubMed1986

A new approach to the oral administration of insulin and other peptide drugs.

The oral administration of peptide drugs is well known to be precluded by their digestion in the stomach and small intestine. As a new approach to oral delivery, peptide drugs were coated with polymers cross-linked with azoaromatic groups to form an impervious film to protect orally administered drugs from digestion in the stomach and small intestine. When the azopolymer-coated drug reached the large intestine, the indigenous microflora reduced the azo bonds, broke the cross-links, and degraded the polymer film, thereby releasing the drug into the lumen of the colon for local action or for absorption. The ability of the azopolymer coating to protect and deliver orally administered peptide drugs was demonstrated in rats with the peptide hormones vasopressin and insulin.

Administration, Oral↗
PubMedDate not supplied

Dietary carbohydrates and synthesis and secretion of apolipoprotein B-containing lipoproteins in rat hepatocytes.

The influence of glucose-, sucrose- and starch-containing diets on the synthesis and secretion of lipoprotein in the density range of very-low-density lipoproteins (VLDLs) and low-density lipoproteins (LDLs) was studied via primary cultures of rat hepatocytes. Apolipoprotein B secreted by hepatocytes from rats fed a sucrose diet was significantly more than in rats fed starch or glucose. This was further confirmed by pulse labeling with [3H]leucine and chase study. Increased synthesis and secretion of cholesterol in lipoproteins of the VLDL and LDL density range and decreased synthesis and secretion of triglyceride in the VLDL fraction were observed in hepatocytes from sucrose-fed animals compared with those fed glucose. This indicates that the VLDL secreted by hepatocytes from sucrose-fed animals was richer in cholesterol but poorer in triglycerides than from glucose/starch- and glucose-fed animals. These findings also suggest an increase in the synthesis and secretion of apolipoprotein B by hepatocytes on sucrose feeding, indicating an association with an increase in cholesterogenesis.

Animals↗