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Biomedical subjects

M Viswanathan

Publications and source records attributed to M Viswanathan.

At least 163 records · Page 9Linked to original sources
PubMed1986

Suppression of sympathetic nervous system by short photoperiod and melatonin in the Syrian hamster.

Exposure to short photoperiod or melatonin treatment brings about gonadal regression in Syrian hamsters. The possible influence of these treatments on the sympathetic nervous system (SNS) in these animals was investigated. Male Syrian hamsters were exposed to either long or short photoperiod or subjected to administration of melatonin or its vehicle solution. Exposure of hamsters to 10 weeks of short photoperiod, significantly reduced the noradrenaline (NA) turnover in the heart. Daily administration of melatonin for 8 weeks also resulted in a similar suppression of NA turnover in the heart. Hamsters that were treated with melatonin maintained a lowered metabolic rate as well, at and below thermoneutral temperature. These findings suggest that in a deep hibernator, short photoperiod could suppress the peripheral sympathetic activity and that melatonin may act as the endogenous mediator.

Animals↗
PubMed1986

Significance of impaired glucose tolerance in an Asian Indian population: a follow-up study.

A prospective study was undertaken in 107 Indians with impaired glucose tolerance (IGT) for a period ranging from 2 to 10 years. On follow-up, 32% still had an impaired glucose tolerance, 32% reverted to normal glucose tolerance and 36% developed diabetes. Careful dietary adherence and weight reduction were found to favour normalisation of glucose tolerance. Poor dietary adherence, persistent obesity and weight gain were found to precipitate diabetes. The study stresses the need for intensive diet therapy in individuals with IGT. Insulin responses were heterogeneous in IGT and non-predictive of the follow-up changes in glucose tolerance.

Adult↗
PubMed1986

Beta cell function in long term NIDDM (type 2) patients and its relation to treatment.

Pancreatic beta cell function was assessed by estimation of fasting and post prandial plasma C-peptide in 183 non-insulin dependent diabetic patients, who were treated with oral hypoglycaemic drugs, for more than 10 years. One-hundred-and-forty-one patients, continued to respond to oral hypoglycaemic agents (Group I) and in 42 the control was not satisfactory and had to be changed over to insulin (secondary failure, Group II). Significant beta cell reserve (PP CP greater than or equal to 0.6 pmol/ml) was present in 89 out of 183 patients (48%) and 83 (93%) of them responded to oral hypoglycaemic agents. Among the 94 patients with low beta cell reserve, 58 (62%) were on oral hypoglycaemic agents and the other 36 (38%) were on insulin. Of the 42 patients with secondary failure to the oral drugs, 36 (86%) had low C-peptide while 6 (14%) had significant C-peptide values. Secondary failure to oral hypoglycaemic agents can also occur in spite of good beta cell reserve. Beta cell reserve was not correlated either to the duration of diabetes or the age at diagnosis of the patients.

Administration, Oral↗
PubMed1986

Insulin response in obese and nonobese offspring of conjugal Indian diabetic parents with increasing glucose intolerance.

Pancreatic beta cell function in response to glucose was assessed in three different groups of offspring of conjugal diabetic parents (OCDP): those with normal glucose tolerance, those with impaired glucose tolerance (IGT), and those with diabetes. Serum immunoreactive insulin (IRI), C-peptide (CP), insulin/glucose (I/G) ratio, and IRI/CP ratios were estimated at fasting and 90 min after glucose load. Insulin secretion, measured as CP, was found to be low even in normal nonobese OCDP, but the change was not reflected in IRI value as the IRI/CP ratio was found to be elevated. The values decreased with increasing glucose intolerance. In obese OCDP, all the parameters were abnormal even among those with normal glucose tolerance, and further deterioration occurred with increasing glucose intolerance. The study shows that insulin secretory defects are detectable even in normal OCDP, and these changes deteriorate with increasing glucose intolerance. Differences are noted in the peripheral concentrations of IRI and CP between obese and nonobese OCDP before development of diabetes. After development of diabetes mellitus, these differences disappear, and the CP and IRI values in both groups are similar and low.

Adult↗
PubMed1986

Beta cell function in insulin-treated non-insulin-dependent diabetic patients.

Non--insulin-dependent diabetes mellitus (NIDDM) patients, 94 in number, who were treated with insulin for various reasons for periods ranging from 2 to 10 years, were investigated to study the effect of long-term insulin therapy and also the effect of anti-insulin antibodies on the beta cell function. Insulin antibody titer and the stimulated C-peptide (CP) did not correlate with the duration of insulin therapy, dose of insulin, or the severity of hyperglycemia. The antibody titers were low in 45%, moderate in 10%, and high in 45%; no correlation was found between the antibody titers and the CP values. Satisfactory control of hyperglycemia was obtained in 54 patients after change of treatment to oral hypoglycaemic agents (OHA). The other 40 patients required continued insulin therapy. The initial CP values were similar in both the groups before initiating the new therapeutic patterns. Those who responded to OHA showed improved CP values on follow-up. The beta cell response to exogenous insulin is heterogeneous in NIDDM patients. In many patients, adequate preservation of beta cell function is present even after long-term insulin therapy. Many of them respond to OHA. Insulin antibodies do not influence the secretory status of the beta cells in NIDDM patients.

Adult↗
PubMed1986

Effects of short photoperiod and melatonin treatment on thermogenesis in the Syrian hamster.

This study investigated whether short photoperiod or melatonin-treatment could alter the thermogenic capacity of Syrian hamsters. Exposure of hamsters to short photoperiod and to exogenous melatonin treatment induced gonadal regression and hypertrophy of brown adipose tissue (BAT). Short photoperiod and melatonin-induced BAT hypertrophy was not accompanied by any change in noradrenaline (NA) turnover in this tissue. The concentration of NA was significantly decreased in hypertrophied BAT, indicating that sympathetic innervation in BAT did not effect its hypertrophy. No improvement in nonshivering thermogenic capacity was noticed in hamsters with increased BAT mass. However, capability for shivering thermogenesis seemed to be enhanced in melatonin-treated hamsters. These observations suggest that melatonin, in addition to mediating short photoperiod-induced gonadal regression in the Syrian hamster, also brings about thermoregulatory adjustments necessary for hibernation.

Adipose Tissue, Brown↗
PubMed1985

Retinopathy in tropical pancreatic diabetes.

In a study of the retinopathy profile of 40 patients with tropical pancreatic diabetes, a form of secondary diabetes seen in tropical countries, diabetic retinopathy was detected in 13 patients. Ten patients had background retinopathy and three patients had proliferative retinopathy requiring laser photocoagulation. In two patients, fibrous retinitis proliferans was present. Three patients had evidence of diabetic maculopathy. To our knowledge, this is the first report of severe and sight-threatening retinopathy occurring with secondary diabetes. Retinopathy in these forms of diabetes has hitherto been considered to be rare or, if present, only of a mild background type.

Adult↗
PubMed1985

Tropical pancreatic diabetes in South India: heterogeneity in clinical and biochemical profile.

Clinical and biochemical studies were carried out in 33 patients with diabetes secondary to chronic calcific, non-alcoholic pancreatitis (tropical pancreatic diabetes) and in 35 Type 2 (non-insulin-dependent) diabetic patients and 35 non-diabetic subjects. Despite lower body mass indices, only 25% of patients with tropical pancreatic diabetes had clinical evidence of malnutrition. There was no history of cassava ingestion. Mean serum cholesterol concentration was significantly lower in the tropical pancreatic diabetic patients (p less than 0.01) in comparison with the Type 2 diabetic patients or non-diabetic subjects, due to a significantly decreased concentration of LDL cholesterol (p less than 0.01) and VLDL cholesterol (p less than 0.05). Basal and post-glucose stimulated concentrations of serum C-peptide were highest in those pancreatic diabetic patients (n = 11) who responded to oral hypoglycaemic drugs, intermediate in the majority (n = 17), who were insulin dependent and ketosis resistant and negligible in a small sub-group (n = 5) who were ketosis prone. The occurrence of microangiopathy in pancreatic diabetic patients was common and similar to that in Type 2 diabetic patients. Thus, tropical pancreatic diabetes in South India appears to be heterogeneous with respect to level of nutrition, severity of glucose intolerance, B-cell function, response to therapy and the occurrence of microvascular complications.

C-Peptide↗
PubMed1985

High prevalence of type 2 (non-insulin-dependent) diabetes among the offspring of conjugal type 2 diabetic parents in India.

The prevalence of Type 2 (non-insulin-dependent) diabetes among offspring of conjugal Type 2 diabetic parents in India was determined by performing oral glucose tolerance tests. Diabetes was present in 50% of offspring, and 12% had impaired glucose tolerance according to the National Diabetes Data Group criteria. Thus, 62% of all offspring had abnormal glucose tolerance tests. This is the highest prevalence rate for diabetes among offspring of conjugal diabetic parents and might represent an ethnic variation of the genetic factors operating in Indian patients with Type 2 (non-insulin-dependent) diabetes.

Adult↗
PubMed1985

HLA, complement C2, C4, properdin factor B and glyoxalase types in South Indian diabetics.

A series of diabetic patients from 3 centres in South India have been tested for HLA A, HLA B, BF, C2, C4A, C4B and GLO types. For insulin-dependent diabetes mellitus (IDDM) patients there was a significant increase in HLA B8, of BF F and decrease of C4 A6. No significant variation in HLA, BF, C2 or GLO frequencies was found in non-insulin-dependent diabetes mellitus (NIDDM) patients, but there was a significant decrease in C4B 1 and an increase in C4B 2. The HLA and BF association in South Indian IDDM patients is very different from that reported previously in North India.

Adolescent↗
PubMed1985

Insulin and C-peptide responses to glucose load in cystic fibrosis.

Immunoreactive Insulin and C-peptide responses to glucose load were estimated in patients with cystic fibrosis and in controls. Both insulin and C-peptide responses were low in cystic fibrosis patients and the changes were more marked in those with glucose intolerance. There appears to be true pancreatic hyposecretion of insulin in patients with cystic fibrosis whereas the peripheral sensitivity of insulin seems to be normal or enhanced.

Adolescent↗
PubMed1984

Serum uric acid concentrations in offspring of conjugal diabetic parents.

Serum uric acid concentrations were measured in offspring of conjugal diabetic parents, in diabetic patients, and in matched nondiabetic controls. The mean uric acid level in offspring of conjugal diabetic parents was significantly higher than in the controls and diabetic patients (P less than 0.001 in the nonobese and P less than 0.05 in the obese). Diabetic patients did not show significant differences in the serum uric acid concentration compared to the controls. The elevated level of serum uric acid in offspring of conjugal diabetic parents could possibly be an early biochemical marker of diabetes.

Adult↗
PubMed1984

Pancreatic beta cell function in offspring of conjugal diabetic parents. Assessment by IRI and C-peptide ratio.

Serum C-peptide and insulin responses to oral glucose load were measured in 69 offspring of conjugal diabetic parents (OCDP). The insulin responses were varied. The non obese OCDP showed higher mean insulin levels than non obese controls while the obese OCDP did not have significant differences in the mean insulin responses compared to obese controls. The C-peptide levels were, however, low in both obese and non-obese OCDP. The IRI/CP ratios were elevated in both groups of OCDP. These results suggest that OCDP have low beta cell function and also possibly a change in the metabolism of insulin at the hepatic level, which is more pronounced in non obese OCDP.

Adolescent↗
PubMed1984

Pinealectomy has no effect on diet-induced thermogenesis and brown adipose tissue proliferation in rats.

The role of the pineal gland in diet-induced thermogenesis (DIT) and growth of brown adipose tissue (BAT) in rats during voluntary overfeeding was studied using pinealectomized and sham-pinealectomized rats. Overfeeding was induced by offering the animals a cafeteria-diet (CD) which contained a selection of highly palatable food items. Rats which were fed CD had significantly increased interscapular brown adipose tissue (IBAT) mass and increased tail-skin temperature indicating the importance of the tail in thermoregulation during DIT. Pinealectomy had no effect on the increase in tail-skin temperature and deposition of IBAT, which were stimulated by CD feeding. These findings suggest that the pineal is not directly involved in modulating the metabolism of BAT in rats.

Adipose Tissue, Brown↗