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Biomedical subjects

K Chopra

Publications and source records attributed to K Chopra.

At least 37 records · Page 2Linked to original sources
PubMed1996

Comparative antioxidant effects of beta-adrenoceptor blockers, calcium antagonists and U-74500A against iron-dependent lipid peroxidation in murine ventricular microsomal membranes.

Recently we have shown that ACE inhibitors and platelet activating factor antagonists inhibit iron-dependent lipid peroxidation in murine ventricular membranes and possess beneficial effects on ischemia and ischemia reperfusion-induced myocardial injury, which has been ascribed to their capacity to scavenge or impair oxygen free radical generation. In the present study we investigated the effects of beta-adrenoceptor blockers and calcium antagonists on iron-dependent lipid peroxidation (LPO) in murine ventricular membranes and compared them with the lazaroid U-74500A, a potent antioxidant. Fe(2+)-vitamin C induced LPO in a concentration- and time-dependent manner, measured as thiobarbituric acid reactive substances (TBARS) formation. Pretreatment of ventricular membranes with gallopamil, verapamil, propranolol and metaprolol at concentrations of 5 microM and higher inhibited Fe(2+)-vitamin C-induced LPO in a concentration-dependent manner with IC50 values of 192.8-208.3 microM; however, they were less potent than U-74500A (IC50 6.8 microM). In contrast, atenolol, timolol, diltiazem and nifedipine inhibited LPO at very high concentrations with IC50 values of 864.5-971.5 microM. Inhibition of LPO may not be due to the drugs' classical pharmacological actions, but rather to their characteristic chemical structures or physicochemical interactions with biological membranes. In view of the pathological importance of LPO in cardiac ischemic injury, inhibition of LPO by gallopamil, verapamil, propranolol and metaprolol may provide additional cardioprotective activity and thus reinforces their beneficial effects in the treatment of ischemic heart disease.

Adrenergic beta-Antagonists↗
PubMed1995

Association of gastroesophageal reflux (GER) with bronchial asthma.

Eighty children with bronchial asthma and ten control cases underwent radionuclide gastroesophagography for the detection of gastroesophageal reflux. Thirty nine per cent asthmatic children demonstrated esophageal reflux on scintiscanning. The ten control subjects had no reflux. The presence of reflux correlated strongly with the presence of nocturnal exacerbation of symptoms. Bronchodilator therapy did not affect the prevalence of GER in asthmatic children.

Asthma↗
PubMed1993

Involvement of oxygen free radicals in the action of BN 52021 (PAF antagonist) to limit myocardial infarct size.

The ability of a PAF antagonist, BN 52021, to limit myocardial infarct size in rat was assessed. Anesthetized rats were subjected to coronary artery ligation for 72 h and infarct size was measured macroscopically using TTC staining. Systolic blood pressure and ECG were monitored. BN 52021 (2.5 and 5 mg/kg i.v.) markedly reduced the infarct size, prevented the loss of R wave, an electrophysiological parameter of ischemic injury, reduced elevated serum MDA levels and demonstrated an inhibition of luminal-enhanced chemiluminescence. There was no marked change in glutathione peroxidase activity with BN 52021 treatment measured at various time intervals after coronary artery ligation. The beneficial effect of BN 52021 on ischemic injury may be due to specific inhibition of PAF-induced activation of neutrophils and consequent decreased amount of cytotoxic reactive oxygen species.

Analysis of Variance↗
PubMed1993

Evaluation of radionuclide gastroesophagography as a suitable screening test for detection of gastroesophageal reflux.

Thirty cases of recurrent pulmonary infection and ten control cases underwent radionuclide gastroesophagography endoscopy, histopathology and barium esophagography to evaluate the clinical efficacy of scintigraphic technique in, detection of gastroesophageal reflux. After ingesting 500 micro curie of Tc-Sulphur colloid mixed in milk, patients esophageal activity was monitored using the gamma camera for forty-five minutes continuously. By using histopathology as standard of comparison, the sensitivity and specificity of radionuclide esophagography was 78.54 and 81.25%, respectively. Because of its physiologic nature, low radiation exposure and convenience, radionuclide esophagography is recommended as a suitable screening test for detecting gastroesophageal reflux where available.

Barium Sulfate↗
PubMed1993

Stomach in portal hypertension.

365 consecutive patient of portal hypertension [Cirrhosis 285, Non-cirrhotic portal fibrosis (NCPF) 50, Extrahepatic portal vein obstruction (EHPVO)-30] were evaluated prospectively over a period of 2 years. Of these, 33 patients underwent successful sclerotherapy with evaluation before and after the same. Portal hypertensive gastropathy (PHG) was found in 56.4% (mild 28.2%, Severe 28.2%) of total patients; while its incidence was 60.6% in cirrhosis, 54% in NCPF and 20% in EHPVO. Incidence of PHG was significantly higher in cirrhotics when compared with non-cirrhotics (60.7% vs 41.25%: p < 0.05). PHG is more common in patients with large esophageal varices as compared to those with small varices (64.1% vs 50.8%: p < 0.05). Overall incidence of gastric varices was 29.3% while its incidence in cirrhosis, NCPF and EHPVO was 22.1%, 44% and 73.3% respectively. Incidence of gastric varices was significantly higher in non-cirrhotics (NCPF + EHPVO) when compared with cirrhotic (p < 0.05) and in patients with large esophageal varices when compared with patients having small esophageal varices (p < 0.05). Peptic ulcer was found in 10.9% patients with portal hypertension. (More than 90% were cirrhotics, mainly alcoholics). 33 patients underwent successful sclerotherapy of which 11 had PHG (mild--6, severe--5) at the beginning of sclerotherapy. After successful sclerotherapy 26 patients had PHG (mild--14, severe--12) p < 0.001). There was no significant difference in incidence of gastric varices before and after sclerotherapy. Incidence of PHG was significantly higher in cirrhotics while gastric varices were seen more commonly in patients with non-cirrhotic portal hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Decrease of myocardial infarct size with desferrioxamine: possible role of oxygen free radicals in its ameliorative effect.

The ability of an iron chelator, desferrioxamine, to inhibit the infarct size in in vivo rat heart was assessed. Anaesthetised rats were subjected to coronary artery ligation (CAL) for 72 hr and infarct size was measured macroscopically using TTC staining. Systolic blood pressure and ECG were monitored. Desferrioxamine (10 mg/kg and 20 mg/kg i.v.) administered half an hour after CAL markedly reduced the infarct size. However, drug treatment did not alter the systolic blood pressure of animals. In addition, desferrioxamine in vitro and in vivo demonstrated an inhibition of rat PMN-evoked and luminol-enhanced chemiluminescence. The capacity of desferrioxamine to impair the generation or to scavenge directly oxygen free radicals may be responsible for its beneficial effect on myocardial infarct size in rats.

Animals↗
PubMed1990

Raised stool and serum IgA levels in undernourished infants with chronic diarrhoea and associated parasitic infestations.

Sixty children with chronic diarrhoea, age ranging from 9 months to 3 years and 15 normal healthy children of same age group, all belonging to the low socio-economic families formed the basis of this study. Fifty-six out of these 60 children were undernourished and were marasmic. Stool examination showed enteropathogenic E. coli in 24 (40 per cent), Ascaria lumbricoides in 12 (20 per cent) and Giardia lamblia in 6 (10 per cent). Coeliac disease was detected in 2 (3 per cent) and combined IgA-IgG deficiencies were found in one case (2 per cent). No cause could be found in 15 (25 per cent) cases. Multiple aetiological factors were found in 7 (12 per cent) cases. Stool IgA levels were significantly elevated in the patients than in the controls and more so in the patients with giardiasis and also in patients with coeliac disease. Serum IgA levels were remarkably raised in the patients with diarrhoea due to enteropathogenic E. coli, indicating probable spilling of gut-associated IgA into the circulation. No IgA was detected in the stool of a dysgammaglobulimic patient, who had both serum IgA and IgG deficiencies.

Child, Preschool↗
PubMed1990

Use of human colostrum in the management of chronic infantile diarrhoea due to enteropathogenic E. coli infection with associated intestinal parasite infestations and undernutrition.

This study reports the management of infants with chronic diarrhoea by colostrum feeding. Eight children with chronic diarrhoea, ranging from 9 months to 3 years of age and all from low socio-economic families, formed the basis of this study. They were undernourished and marasmic. Stool examination showed enteropathogenic E. coli in all eight cases, Ascaris lambricoidis in four, and Giardia lamblia in one. Patients with chronic diarrhoea, in whom no cause was found were excluded from this study. All eight patients were administered 20 ml fresh human colostrum daily for 7 days. In addition, those patients, who had giardiasis, received metronidazole treatment, while cases with ascariasis were given antihelminthic therapy irrespective of the groups they belonged to. Our results indicated effective antidiarrhoea action of colostrum in some patients with chronic diarrhoea of infective origin.

Ascariasis↗
PubMed1990

The dopaminergic actions of B-HT 920.

B-HT 920 (2-amino-6-allyl-5,6,7,8-tetrahydro-4H-thiazolo-[4,5-d]-azepine), an alpha 2-adrenoceptor agonist has been reported to modulate dopamine (DA) receptor activity. Earlier studies speculated the DA autoreceptor action of B-HT 920. However, some recent studies have indicated that the stimulatory effects of B-HT 920 are sensitive to blockade by sulpiride and haloperidol, suggesting a postsynaptic D2-dopamine receptor action. The article briefly reviews the current concepts about DAergic actions of B-HT 920.

Animals↗
PubMed1989

Antibody response of infants in tropics to five doses of oral polio vaccine.

Sixty-two infants 1-12 months of age were administered five doses of trivalent oral polio vaccine (TOPV) at intervals of 4 weeks. The seroconversion achieved were 88.7, 93.5 and 96.5 per cent for type I, II, and III polioviruses. These seroconversion rates are significantly better when compared to seroconversion achieved after two and three doses of trivalent oral polio vaccine. Factors which were considered in previous studies to be responsible for low seroconversion rates viz. interference by enteroviruses, breast feeding, malnutrition, and age were found to be insignificant when five doses of oral polio vaccine were given. It is possible that these effects were overcome by increasing the number of doses of trivalent oral polio vaccine.

Antibody Formation↗