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Biomedical subjects

R V Kumar

Publications and source records attributed to R V Kumar.

13 recordsLinked to original sources
PubMed1992

Antidiabetic effect of a glycoside of pelargonidin isolated from the bark of Ficus bengalensis Linn.

The antidiabetic effect of a dimethoxy derivative of perlargonidin 3-O-alpha-L rhamnoside (250 mg/kg, single dose study and 100 mg/kg/day long term study) isolated from the bark of Ficus bengalensis Linn. has been compared with that of glibenclamide (2 mg/kg and 0.5 mg/kg/day respectively) in moderately diabetic rats. The single dose glycoside treatment decreased fasting blood glucose by 19% and improved glucose tolerance by 29%. The corresponding effects of glibenclamide were 25% and 66% respectively over the control values. On one-month treatment the fasting blood glucose levels went down almost to half of the pretreatment levels in both the groups and their glucose tolerance improved by 41% in glibenclamide group and by 15% in glycoside treated group. Urine sugar decreased to traces in both the groups and they appeared healthy. In vitro studies showed that insulin secretion by beta-cells was more in presence of the pelargonidin derivative than in presence of a leucocyanidin derivative, reported to be a good anti-diabetic agent.

Animals↗
PubMed1992

Frozen sections--a retrospective study.

Two hundred and forty-four (244) specimens were examined by frozen section (FS) from 1987 through 1988 at the Kidwal Memorial Institute of Oncology. Of these, eleven (11) were performed for evaluation of the surgical margin of tumours and fifty four (54) for detection of lymph node metastasis. All these examinations (65) proved to be hundred percent (100%) accurate. The remaining 179 frozen sections were performed for the diagnosis of an unknown pathologic process. Of these, 44.69 percent were precisely diagnosed, in 41.9 percent the pathologic process was correctly but not precisely diagnosed, in 11.17 per cent the diagnosis was deferred and remaining 2.24 percent were incorrectly diagnosed with no harmful consequences to the patients. By eliminating the cases where diagnosis was deferred and combining results of "precise diagnosis" with those of "correct pathologic process", the overall accuracy rate was 98.2 percent. Thus, FS has greater benefit when used for the general diagnosis of an unknown pathologic process rather than for an exact or precise diagnosis.

Evaluation Studies as Topic↗
PubMed1991

The nature of inhibition of 3-hydroxy-3-methylglutaryl CoA reductase by garlic-derived diallyl disulfide.

A concentration dependent inhibition of 3-hydroxy-3-methylglutaryl CoA (HMG CoA) reductase was found on preincubation of microsomal preparations with diallyl disulfide, a component of garlic oil. This inhibited state was only partially reversed even with high concentrations of DTT. Glutathione, a naturally occurring reducing thiol agent, was ineffective. The substrate, HMG CoA, but not NADPH, was able to give partial protection for the DTT-dependent, but not glutathione-dependent activity. The garlic-derived diallyl disulfide is the most effective among the sulfides tested for inhibition of HMG CoA reductase. Formation of protein internal disulfides, inaccessible for reduction by thiol agents, but not of protein dimer, is likely to be the cause of this inactivation.

Allyl Compounds↗
PubMed1991

Inhibition of protein synthesis by antagonists of calmodulin in Ehrlich ascites tumor cells.

Several recent publications indicate that Ca2+ is required for protein synthesis in mammalian cells, including the Ehrlich ascites tumor cell. The present communication examines whether the effects of Ca2+ might be mediated through calmodulin or a related protein. Four calmodulin antagonists belonging to different chemical categories were used to provide evidence of calmodulin involvement. Three of the antagonists inhibited protein synthesis in intact cells; 50% inhibitory concentrations were 10 microM calmidazolium, 12 microM N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W7) and 17.5 microM trifluoperazine (TFP). Initiation was preferentially inhibited as indicated by an increase in the 80S monomers accompanied by a significant disaggregation of polyribosomes. All the antagonists also inhibited protein synthesis initiation in the cell-free protein-synthesizing system; 50% inhibitory concentrations for compound 48/80, calmidazolium, TFP, and W7 were 10 microM, 125 microM, 300 microM and 500 microM, respectively. A weak analogue of W7 inhibited only 20% at 1000 microM. Inhibition in the cell-free system was reversed by the addition of exogenous calmodulin in all four cases. The levels of 43S complexes were significantly elevated with all four antagonists, indicating a block in the utilization of 43S complexes. The similarity of the effects of four distinct classes of antagonists and their ready reversal by exogenous calmodulin leads us to suggest that there may be a role for calmodulin or a very similar calcium-binding protein in protein synthesis.

Animals↗
PubMed1991

Unusual splenic metastasis from oesophageal cancer.

The most common visceral metastasis from oesophageal carcinomas are lungs and liver. A case of splenic metastasis from a squamous carcinoma of oesophagus is reported. To our knowledge, splenic metastasis without any nodal disease has not been described previously. The pattern of reported metastasis is summarised.

Carcinoma, Squamous Cell↗
PubMed1990

Malignant fibrous histiocytoma of bone.

Malignant fibrous histiocytoma (MFH) of bone is a malignant primary bone tumour that is being increasingly recognised, as more details emerge in the literature regarding its natural history and precise (although sometimes diverse) histological appearance. When the whole bulk of a malignant bone tumour fits the criteria laid down, the designation of MFH seems appropriate. Seven cases of MFH of bone were encountered from a total of 220 primary malignant bone tumours in our files over a 4-year period. The metaphyses of long bones were the most common sites harbouring the tumour, and a wide age range was represented. Amputation was the treatment of choice in all cases. The relevant literature is reviewed.

Adolescent↗
PubMed1990

Extraskeletal myxoid chondrosarcoma--a review of three cases.

During a ten year period, only three cases of extraskeletal myxoid chondrosarcoma were seen at Kidwai Memorial Institute of Oncology, South India. All were adults; the youngest patient was twenty-six years old and the oldest was seventy five years old. The tumours arose in the soft tissues of the extremities Our findings indicated that tumour size, site and morphology had no bearing on prognosis. With surgery radiotherapy and chemotherapy, two patients survived for four years and nine months respectively and one patient is still on follow up, five months after treatment.

Adult↗
PubMed1989

Mechanism of inhibition of polypeptide chain initiation in calcium-depleted Ehrlich ascites tumor cells.

Protein synthesis in Ehrlich ascites tumor cells is inhibited when cellular calcium is depleted by the addition of EGTA to the growth medium. This inhibition is at the level of polypeptide chain initiation as evidenced by a disaggregation of polyribosomes accompanied by a significant elevation in 80-S monomers. To identify direct effects of calcium on the protein synthesis apparatus we have developed a calcium-dependent, cell-free protein-synthesizing system from the Ehrlich cells by using 1,2-bis(O-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid (BAPTA), a recently developed chelator with a high (greater than 10(5)) selectivity for calcium (pKa = 6.97) over magnesium (pKa = 1.77). BAPTA inhibits protein synthesis by 70% at 1 mM and 90% at 2 mM. This effect was reversed by calcium but not by other cations tested. The levels of 43-S complexes (i.e., 40-S subunits containing bound methionyl-tRNAf.eIF-2.GTP) were significantly lower in the calcium-deprived incubations, indicating either inhibition of the rate of formation or decreased stability of 43-S complexes. Analysis of 43-S complexes on CsCl gradients showed that in BAPTA-treated lysates, 40-S subunits containing eIF-3, completely disappeared and the residual methionyl-tRNA-containing complexes were bound to 40-S subunits lacking eIF-3. Our results demonstrate a direct involvement of Ca2+ in protein synthesis and we have localized the effect of calcium deprivation to decreased binding of eIF-2 and eIF-3 to 40-S subunits.

Animals↗
PubMed1989

Histomorphology of Wilms' tumour.

Eleven cases of Wilms' tumour received at Banglore Medical College, Bangalore are being studied focussing on the histopathological appearance of these tumours. One case exhibiting neuronal and glial differentiation, which is a rare observation, was noticed and is reported. The clinicopathological features and a brief review of literature are being presented.

Child↗
PubMed1989

Antidiabetic effect of a leucocyanidin derivative isolated from the bark of Ficus bengalensis Linn.

A dimethoxy derivative of leucocyandin 3-O-beta-D-galactosyl cellobioside isolated from the bark of F. bengalensis Linn demonstrated antidiabetic action. On oral administration, it decreased blood sugar very significantly both in normal and moderately diabetic rats and increased serum insulin significantly in the latter at a dosage of 250 mg/kg for a 2 hr period. During one month treatment of the diabetic rats orally with the active principle, at a dosage of 100 mg/kg, there was a significant decrease in blood and urine sugar, certain lipid components in serum and tissues and glucose-6-phosphatase activity in liver, but significant increase in body weight and the activities of hexokinase and HMGCOA reductase in tissues as compared to diabetic control. The mechanism of action of the principle may be related to its protective/inhibitory action against the insulin degradative processes.

Animals↗
PubMed1987

Pharmacokinetics of methotrexate in Indian children and its relationship to nutritional status.

Any significant change in the pharmacokinetics of an anticancer drug would have a bearing on its therapeutic efficacy and toxicity. Nutritional deficiencies have been shown to affect the pharmacokinetics of a drug. Since malnutrition and undernutrition are widely prevalent in India, the effect of initial nutritional status on the overall kinetics of methotrexate (MTX) administered to cancer patients appeared to be of practical importance. A study of 6 Indian children with malignancies was made to examine the pharmacokinetics of low dose MTX and its relationship to the nutritional status. The results indicate that the relative weight correlates well with the anthropometric parameters, nutritional parameters and dietary intake and may be used as a marker of nutritional status.

Adolescent↗