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Biomedical subjects

M K Sinha

Publications and source records attributed to M K Sinha.

80 records · Page 5Linked to original sources
PubMedDate not supplied

Serum and pancreatic immunoreactive insulin (IRI) and proinsulin-like component (PLC), serum IRI and PLC response to different stimuli in normal subjects and organic hyperinsulinism.

The serum levels of total immunoreactive insulin (IRI) and proinsulin-like component (PLC) in the fasting state and following the administration of insulin secretagogues in 5 patients with organic hyperinsulinism and age and sex matched normal subjects are reported. Diagnosis of organic hyperinsulinism could be established in all instances on the basis of the inappropriately high total serum IRI levels for the corresponding blood glucose values; such an abnormal relationship was not seen in normal subjects, and was further enhanced by insulin secretagogues. Unrestrained insulin secretion in organic hyperinsulinism was enhanced following the administration of glucose, tolbutamide, glucagon or amino acids; the last 2 stimuli are known to be ineffective in causing insulin secretion in the presence of hypoglycemia in normal subjects. Four patints had insulinomas and one probably had islet cell hyperplasia or abnormal function of islet cells. Chromatography of serum IRI to quantitate PLC is a useful adjunct to the diagnosis of organic hyperinsulinism as in the fasting state the proportion of PLC is always elevated, above the normal range of 5-22%. Following the administration of insulin secretagogues there was pronounced increase in total serum IRI in organic hyperinsulinism but the proportion of PLC generally decreased, suggesting thereby that mojor increase in IRI was due to release of stored granular IRI which is known to have a low proportion of PLC.

Adenoma, Islet Cell↗
PubMedDate not supplied

Orally administered liposome-entrapped insulin in diabetic animals. A critical assessment.

We investigated the effects of liposome-entrapped insulin (LEI) administered orally one-half to one-tenth of previously reported doses, on plasma glucose and insulin in the spontaneously diabetic BB Wistar rat and in alloxan-induced diabetic rabbits. Incorporation of insulin within the liposome fraction ranged from 15 to 23%. Radioimmunoassay of Triton X-100 treated LEI yielded insulin values in high agreement (82 +/- 10%) with those predicted based on estimated incorporation. Whereas insulin alone, or liposomes devoid of insulin had no effect, LEI 5 U/kg significantly reduced glucose and raised insulin in 54% of rats (13 of 24) and 67% of the rabbits (6 of 9). Among the rats that responded, blood glucose fell from a basal of 318 +/- 21 mg/dl to a nadir of 186 +/- 22 mg/dl at 2 h (p less than 0.001); values at 1, 2 and 4 h were all significantly less (58-69%) than basal. Similarly, glucose declined significantly for 3 h post LEI in the rabbits while IRI rose from 30 +/- 7 micro U/ml to a peak of 399 +/- 75 micro U/ml at 1 h (p less than 0.001); values at 2 and 3 h remained significantly elevated. Some batches of LEI failed to reduce glucose despite apparently adequate incorporation, while even with effective batches some animals failed to respond. Thus, although orally administered LEI can be effective, their stability and effectiveness are not completely predictable.

Administration, Oral↗
PubMedDate not supplied

Oxidative stress in patients with essential hypertension.

BACKGROUND: Free oxygen radicals react with membrane lipids to form lipid hydroperoxides, a destructive process known as lipid peroxidation. Lipid hydroperoxides decompose to form a variety of products including malondialdehyde, which is used as an indicator of the oxidative damage of cells and tissues. Endogenous antioxidant enzymes such as superoxide dismutase counteract the oxidative damage from oxidative stress. There is increasing evidence that free radicals are involved in the pathogenesis of hypertension by altering endothelial function. We evaluated the oxidative stress and endogenous enzymatic antioxidant status in patients with essential hypertension before and 3 months after treatment with antihypertensives. METHODS: Fifty patients with essential hypertension attending the outpatient services of the Department of Medicine, Institute of Medical Sciences, Banaras Hindu University and 20 age- and sex-matched healthy controls were studied. The serum malondialdehyde and superoxide dismutase levels were measured in patients at the time of presentation and after 3 months of antihypertensive treatment. No antioxidants were given to the patients during the period of the study. RESULTS: The mean (SD) serum malondialdehyde level was found to be significantly higher (0.33 [0.07] mmol/L) in patients with hypertension compared with controls (0.21 [0.05] mmol/L; p < 0.001). This showed a significant decrease following antihypertensive therapy (0.23 [0.06] mmol/L; p < 0.001) compared with pre-treatment values. The serum superoxide dismutase activity was significantly lower in patients (6.93 [1.35] mg protein/ml of serum) compared with controls (20.12 [3.65] mg protein/ml serum; p < 0.001) at the time of presentation and, compared with the pre-treatment values, increased significantly after 3 months of treatment (10.66 [2.91] mg protein/ml of serum; p < 0.001). CONCLUSION: Our study shows that essential hypertension is associated with increased oxidative stress and reduced antioxidant status. Adequate control of blood pressure with antihypertensive therapy decreases oxidative stress and improves the antioxidant status in these patients.

Case-Control Studies↗