Pancreatic beta cell function in normoglycaemic offspring of diabetic parents

The aim of the study was to look for any time-realted fluctuation in the pancreatic beta cell function in normal offspring of diabetic parents, over a period of three years. Serum insulin (IRI) and C-peptide (CP) responses to oral glucose were reevaluated three years after the initial study in 25 normoglycaemic offspring of conjugal Type 2 diabetic parents. The mean area under the curve of IRI (AUC IRI) response was higher than normal control value in the offspring at both time points (P < 0.01) and the two values did not differ much. The 2 hr IRI was also significantly higher (P < 0.05) than the control value. CP responses at both time points in the offspring did not differ from the mean control value. Wide fluctuations in the individual IRI were noted on follow-up despite similar plasma glucose response. Follow-up IRI was higher in 6, lower in 5 (+/- 25% of the initial) and remained unaltered in the other 4 offspring. The corresponding CP showed increased values in 3, decreased values in 5 and no change in 7 offspring. The fluctuations were nonuniform in nature among the individuals studied. Disparity between the IRI and CP responses were present in 5 offspring during the follow-up. This study thus shows that wide fluctuations in insulin responses occur even in the normoglycaemic offspring of diabetic parents.

Differences in plasma insulin responses in urban and rural Indians: a study in southern-Indians

Fasting and 2 h post glucose plasma immunoreactive insulin (fasting IRI and 2 h IRI) responses were measured in urban (n = 149) and rural (n = 40) individuals with normal glucose tolerance during an epidemiological survey. In this survey, 900 urban and 1038 rural subjects were screened for glucose intolerance by capillary blood sampling. The respective response rates were 91% and 88%. We had planned to collect venous blood for IRI estimation, i.e. from 180 urban and 200 rural subjects. The compliance for the same was poor from the rural subjects and therefore the number available for IRI estimation was small. The mean +/- SD ages of the urban and rural groups were similar (35.3 +/- 9.9 and 38.6 +/- 13.1 years, respectively). The rural population had lower body mass index (BMI) and subscapular:triceps ratio compared to the urban group (p < 0.001). The total calorie consumption was lower and physical activity was higher in rural population. Fasting and 2 h insulin values in urban population were 16.6 +/- 9.4 mU l-1 and 60.6 +/- 42.5 mU l-1 and in rural 6.7 +/- 5.1 mU l-1 and 32.4 +/- 27.8 mU l-1, respectively; the values being significantly lower in the rural population (p < 0.001). Multiple regression analysis showed that in urban population the fasting insulin was correlated to the BMI and the 2h IRI to 2 h glucose, BMI and the subscapular:triceps ratio. In the rural population, similar results were obtained, except in that the 2 h IRI was influenced by the gender also.(ABSTRACT TRUNCATED AT 250 WORDS)

Specific, non-angiotensin, [125I]CGP 42112 binding sites in rat spleen macrophages

We report the novel expression of a high affinity non-angiotensin II binding site to [125I]CGP 42112, predominantly localized to the red pulp of the rat spleen and to isolated rat spleen macrophages. Binding is not inhibited by angiotensin II, related peptides or AT1 or AT2 receptor ligands, and is not affected by several growth factors and cytokines involved in macrophage function. Thus, CGP 42112 recognizes binding sites other than angiotensin II AT2 sites in rat macrophages. CGP 42112 and related peptides might influence the regulation of macrophage function.

Height at onset of insulin-dependent diabetes in children in southern India

A total of 250 children with insulin-dependent diabetes mellitus (IDDM), having age at onset of diabetes < or = 18 years were studied. Their height at onset of diabetes was compared with that of the normal age- and sex-matched control population. No differences were observed in the heights of the two groups of children. Therefore, our results were similar to that found in Japan and differed from the reports in European children with IDDM in whom an increased growth velocity was noted before the onset of IDDM.

[125I]CGP 42112 reveals a non-angiotensin II binding site in 1-methyl-4-phenylpyridine (MPP+)-induced brain injury

1. Intracerebral injection of the oxidative metabolite of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), 1-methyl-4-phenylpyridine (MPP+), into the substantia nigra of adult rats resulted in a lesion at the injection site. 2. Using autoradiography, we localized specific [125I]CGP 42112 binding that was not recognized by angiotensin II or angiotensin II AT1 or AT2 receptor-selective ligands. 3. Our results suggest that [125I]CGP 42112 may be binding to activated microglia that appear at the lesion site.

Heterogeneous expression of angiotensin II AT1 receptors in neointima of rat carotid artery and aorta after balloon catheter injury

We examined the expression of angiotensin II receptor subtypes and angiotensin-converting enzyme in the rat aorta and carotid artery at 1, 2, 4, 8, 15, and 30 days after balloon catheter injury or sham surgery. The AT1 receptor expression was enhanced in the neointima at 8 days in the aorta and carotid artery compared to that in intact media. Maintenance of the high expression of AT1 receptors in the neonintimal tissue at 15 and 30 days was localized to a subpopulation of neointimal cell close to the lumen of the vessel and was correlated to the distribution of smooth muscle cells immunoreactive to proliferating cell nuclear antigen. During the initial stages after injury, binding of [125I]351A to angiotensin-converting enzyme was significantly decreased in both the intima/media layers as well as adventitia in carotid artery and aorta. Binding of [125I] 351A to angiotensin-converting enzyme was significantly lower in the neointima compared to that in the intima/media of intact vessels. Our results reveal that the expression of AT1 receptors is heterogeneous in the neointima, and suggest that enhanced expression of AT1 receptors in the balloon catheter-injured carotid artery and aorta may be limited to proliferating intimal smooth muscle cells.

Risk of pancreatic carcinoma in tropical calcifying pancreatitis: an epidemiologic study

To assess the risk of pancreatic cancer in subjects with tropical calcifying pancreatitis (TCP), we have followed 185 patients with TCP from the Diabetes Research Center in Madras, India for an average of 4.5 years. The diagnosis of TCP was based upon long-standing epigastric pain, laboratory tests, presence of pancreatic calculi, endoscopic retrograde cholangiopancreatography (ERCP) findings, and ultrasonography. During the follow-up period, 24 patients died from all causes, with 6 deaths (25%) from cancer of the pancreas. Three pancreatic cancers were biopsy positive. Average age at onset of pancreatic cancer was 45.6 +/- 7.3 years--considerably younger than for Western populations. When compared with the background pancreatic cancer rate, subjects with TCP appear to have a significantly increased risk of pancreatic cancer: relative risk = 100, 95% CI = 37-218. Even under the most stringent assumptions (restricting the analysis to biopsy-proven cases, assuming that the true background rate of pancreatic cancer in Madras resembles high-risk Western populations, assuming that tropical pancreatitis begins at birth) the risk is still elevated: relative risk = 5, 95% CI = 1.03-3-14.6. The exact mechanism linking various forms of pancreatitis to pancreatic cancer remains to be elucidated.

Autoradiographic localization and characterization of angiotensin II receptor subtypes in the rat thymus

Angiotensin II (ANG II) receptors were present in the thymus of newborn rats (179 +/- 34 fmol/mg protein). In newborns, binding was predominantly localized in the trabecula, and was selectively displaced by the AT2 ligand CGP 42112A (83-85%) and to a lower extent by the AT1 antagonist losartan (15-17%), indicating a marked predominance of AT2 receptors. Angiotensin II binding was very low in the cortical and medullary areas in the thymus of newborn rats and was no longer detected in the thymus of 4- and 8-week-old rats. No detectable binding for the ACE inhibitor [125I]351A was observed in the thymus of the rat, regardless of the age studied. Our results indicate a possible role for circulating ANG II during development of the thymus with no clear correlation to lymphocyte maturation.

Delayed onset of diabetes in children of low economic stratum--a study from southern India

Influence of the socioeconomic status on the age at onset of insulin-dependent diabetes mellitus (IDDM) was analysed in 614 patients who developed diabetes < or = 20 years. The peak occurrence was seen at 11 years in girls (n = 293). The boys (n = 321) showed multiple peaks between 11 and 18 years. In the urban patients (n = 463), the peak was at 11 years in contrast to a delayed peak at 18 years in the rural group (n = 151). When analysed with respect to the family income, the higher income group (HIG) (Rs > 2000/month) showed a sharp peak at 11 years whereas the lower income group (LIG) showed a peak at 18 years (chi 2 = 7.2, P = 0.007). The median body weight of the LIG was lower compared to the HIG. Although the exact cause for the delayed age at onset of IDDM in the rural or LIG is not known, it is likely to be a consequence of the lower socioeconomic and nutritional status (indicated by low body weight) and probably indicates the influence of environmental factors in the pathogenesis of the disease.

Fasting plasma glucose in the diagnosis of diabetes mellitus: a study from southern India

The usefulness of fasting plasma glucose (FPG) in the diagnosis of diabetes mellitus was assessed in Asian Indians in South India. Oral GTT values in 570 newly screened adults were studied. Taking the WHO criteria of 2 h plasma glucose (PG) of > or = 11.1 mmol l-1 for diagnosis of diabetes, the validity of a FPG of > or = 7.8 mmol l-1 cut off value for diabetes was assessed. Using the regression analysis, the correlations of the FPG to 2 h PG were examined. Among the 268 with 2h PG value of > or = 11.1 mmol l-1, 205 (76.5%) had FPG > or = 7.8 mmol l-1. Sensitivity of FPG was 76.5% for diagnosis of diabetes and its specificity was 99%. An exponential regression model gave the best fit for FPG vs 2 h PG and using the regression equation, the predicted FPG for a 2 h PG of 11.1 mmol l-1 was 7.05 mmol l-1. Sensitivity increased to 90.3% with FPG of 7.05 mmol l-1 while the specificity remained at 92%. It is concluded that in the south Indian subjects, the sensitivity for diagnosis of diabetes with FPG of > or = 7.8 mmol l-1 was 76.5%; and it increased to 90.3% with FPG of > or = 7.05 mmol l-1.

Glomerular angiotensin II receptor subtypes during development of rat kidney

We used quantitative autoradiography to investigate distribution of angiotensin II (ANG II) receptor subtypes during development of the kidney in the rat. In fetal, newborn, and 3-day-old rats, immature glomeruli in the form of comma and S-shaped bodies, located in the nephrogenic zone of the renal cortex, expressed only the angiotensin AT2 receptor subtype. Conversely, the juxtamedullary glomeruli, in more advanced developmental stages, expressed only the AT1 subtype. Similarly, maturing and fully developed glomeruli, present in 1-, 2-, and 8-wk-old rats, expressed only AT1 receptors. In the kidney medulla, there was a similar change in ANG II receptor subtype expression, with the AT2 subtype expressed earlier and the AT1 subtype later during development. Our results demonstrate a selective expression of ANG II receptor subtypes during kidney development. We have found glomerular and medullary AT1 receptors only at developmental stages when kidney function has matured. Conversely, AT2 receptors are expressed only in immature structures, suggesting that they may have a role during kidney organogenesis.

Positive association in the absence of linkage suggests a minor role for the glucokinase gene in the pathogenesis of type 2 (non-insulin-dependent) diabetes mellitus amongst south Indians

Mutations of the glucokinase gene have been implicated in the development of glucose intolerance in pedigrees with maturity-onset diabetes of the young. However, the contribution of the glucokinase gene to the aetiology of common Type 2 (non-insulin-dependent) diabetes mellitus is uncertain. We have studied the role of the glucokinase gene in the pathogenesis of Type 2 diabetes in South Indians, using both population-association and linkage methodology. A pair of CA-repeat sequences (GCK(3') and GCK(5')) straddling the glucokinase gene were employed as markers, each subject being typed using the polymerase chain reaction and polyacrylamide gel electrophoresis. Comparisons of allele frequencies at these markers were made between 168 Type 2 diabetic subjects and 70 racially-matched control subjects. No differences in allele frequencies were apparent at the GCK(5') marker; however, there were significant differences in allele frequencies at the GCK(3') marker between the Type 2 diabetic subjects and control subjects (chi 2 = 11.6, df = 3, p = 0.009) with an increase of the z allele (78.0% vs 66.4%) and a decrease of the z + 2 allele (13.7% vs 25.0%) amongst the diabetic subjects. Linkage between glucose intolerance and the glucokinase gene was studied in 53 nuclear pedigrees under a variety of genetic models. Linkage was excluded (lod score < -2) at a recombination fraction of zero under five of the ten models used and highly unlikely (-2 < lod score < -1) under the others. The combination of positive association and negative linkage suggests that glucokinase acts as a minor gene influencing the development of Type 2 diabetes within this population.

Vascular melatonin receptors

High-affinity melatonin receptors are expressed in the tail artery of the rat and arteries forming the circle of Willis of the rat and certain primates. The characteristics of the vascular melatonin receptors seem to be similar to the ones described in the central nervous system. The expression of vascular melatonin receptors in the rat is differentially regulated by factors such as strain and age, and in the female by reproductive hormones. Functional studies using the caudal artery of the rat suggest that melatonin regulates vascular tone. The highly restricted distribution of melatonin receptors in arteries involved in regulating blood flow to areas involved in heat dissipation suggests that vascular melatonin receptors may have a specific function in thermoregulatory homeostasis.

Localization of angiotensin AT1 receptors in the rat heart conduction system

We characterized angiotensin II receptor subtypes in the conduction system of the rat heart using quantitative autoradiography. In both the sinoatrial and atrioventricular nodes, binding could be totally displaced by losartan, and was insensitive to PD 123177, indicating that angiotensin II receptors in the conduction system of the rat heart belong to the AT1 subtype. Angiotensin AT1 receptors could play a direct role in the regulation of the heart chronotropic properties.

Maternal age and birth order of young IDDM patients. A study from southern India

OBJECTIVE

To assess the effects of maternal age and birth order on the risk of IDDM in Asian Indians.

RESEARCH DESIGN AND METHODS

Data from a diabetes registry in Madras, India, was used to find IDDM patients diagnosed before 20 yr of age. A questionnaire was used to elicit clinical details of subjects.

RESULTS

Children with mothers < or = 24 yr of age had a higher percentage of IDDM. Children with lower birth orders had a higher prevalence of IDDM.

CONCLUSIONS

The risk of IDDM in children is increased in children with lower birth orders, born of younger mothers.

Differential expression of melatonin receptors in spontaneously hypertensive rats

Quantitative autoradiography was used to compare melatonin receptors in brain areas and arteries of young (4 weeks old) and adult (14 weeks old) spontaneously hypertensive rats (SHR) to those in age-matched normotensive controls, Wistar-Kyoto (WKY) rats. Age and strain influenced the number of melatonin receptors in an anatomically selective manner, and the most striking changes occurred in arterial receptors. Melatonin receptors were not detectable in the anterior cerebral arteries of adult SHR. In the caudal artery, melatonin receptors decreased with age in both strains, but the decrease was more pronounced in SHR. When compared to age-matched WKY rats, the number of caudal artery receptors was higher in young and lower in adult SHR. The number of melatonin receptors was higher in the area postrema of adult SHR when compared to adult WKY rats, but in the suprachiasmatic nucleus, no such differences between the two strains were present. Alterations in receptor density were not accompanied by changes in binding affinity. Our results indicate that in the rat melatonin receptors show different developmental patterns according to location and that the receptors may be expressed differentially in genetic hypertension.

The genetics of non-insulin-dependent diabetes mellitus in south India: an overview

Non-insulin-dependent diabetes mellitus affects approximately 10% of urban Indian and Indian migrant populations and as such carries major health implications for these groups. Whilst a strong genetic component to the aetiology of non-insulin-dependent diabetes mellitus is incontestable, progress in identifying the specific genetic determinants involved in its pathogenesis has been slow. In studies of South Indian pedigrees, preliminary segregation analysis indicates that non-insulin-dependent diabetes mellitus is likely to be a polygenic disease. A number of candidate genes have been studied with the aim of demonstrating either association or linkage with the disease; in South Indians the only positive results thus far have been associations between non-insulin-dependent diabetes mellitus and the genes for insulin, apolipoprotein D and complement component C4B. However, it seems likely that these genes contribute only a small proportion of the genetic susceptibility to non-insulin-dependent diabetes mellitus in this ethnic group and that the major genes underlying glucose intolerance remain to be determined.

Glucagon response to glucose load in offspring of conjugal type 2 diabetic parents in south India

Immunoreactive glucagon responses were measured in 21 normoglycaemic adult offspring of non-insulin dependent (Type 2) diabetic parents, in the fasting state and during an oral glucose tolerance test. In 7 of the 21 offspring, the mean fasting immunoreactive glucagon value was significantly lower than the control value (p < 0.001). In this group, glucose stimulation did not produce inhibition of immunoreactive glucagon secretion. The insulin response in this group was not significantly different from the values in the other study groups. In the other 14 offspring, the pattern of glucagon response to glucose stimulation was similar to controls. It is likely that this non-suppressive effect of glucose on immunoreactive glucagon in some of the "prediabetic" individuals is an early change in the alpha cell function during the natural history of non-insulin dependent diabetes in Asian Indian subjects.

Balloon angioplasty enhances the expression of angiotensin II AT1 receptors in neointima of rat aorta

Angiotensin II is a vasoactive peptide and may act as a growth factor in vascular smooth muscle cells. Experimental injury of the rat aorta causes rapid migration of medial smooth muscle cells and their proliferation resulting in the formation of neointima. We have examined, using quantitative autoradiography, the expression of angiotensin II receptor subtypes AT1 and AT2, and angiotensin-converting enzyme, in the neointima formed in the rat thoracic aorta 15 d after balloon-catheter injury. In contrast to the normal aortic wall, which contained both AT1 and AT2 receptors (80% and 20%, respectively), neointimal cells expressed almost exclusively angiotensin II AT1 receptors. The apparent number of these receptors was fourfold higher in the neointima compared to that in the normal aortic wall. The affinities of the neointimal receptors to angiotensin II or to the AT1 receptor antagonist, losartan, were not different from those in the normal aortic wall. Angiotensin-converting enzyme binding in the neointima was not different from that in the media of the uninjured aorta. Our data suggest that angiotensin II AT1 receptors may have a significant role in injury-induced vascular smooth muscle proliferation and migration.

The islet amyloid polypeptide gene and non-insulin-dependent diabetes mellitus in south Indians

Islet amyloid polypeptide (IAPP), otherwise called amylin, is the monomeric component of islet amyloid. Deposition of this amyloid is a characteristic feature of non-insulin-dependent diabetes mellitus in humans and may play a role in the pathogenesis of the disease. As such, abnormalities in the structure or expression of the IAPP gene might contribute to the inheritance of this condition. The IAPP gene was studied in a well-characterised population of 62 unrelated Dravidian subjects with non-insulin-dependent diabetes mellitus and 56 normal Dravidian controls, using a restriction fragment length polymorphism generated by PvuII digestion. Genotype and allele frequencies did not differ between diabetic subjects and controls. Taken together with recent findings in Europid and other racial groups, an abnormality of the IAPP gene is highly unlikely to represent a major gene for the development of non-insulin-dependent diabetes mellitus.

Prevalence of glucose intolerance in Asian Indians. Urban-rural difference and significance of upper body adiposity

OBJECTIVE

To evaluate the prevalence of NIDDM and IGT in the urban and rural areas in southern India.

RESEARCH DESIGN AND METHODS

Two populations of the same ethnic background, but different socioeconomic background were chosen for this study. Nine-hundred urban people and 1038 rural subjects were studied. Fasting and 2-h post-glucose capillary blood samples after a 75 g oral glucose load (WHO criteria) were obtained in these randomly selected adults (greater than or equal to 20 yr of age).

RESULTS

Using the WHO criteria, the prevalence of NIDDM, adjusted to the age of the respective general population, was 8.2% in the urban and 2.4% in the rural populations. The prevalence was 8.4 and 7.9%, respectively, in urban men and women, and 2.6 and 1.6% in rural men and women. The age-adjusted prevalence of IGT was 8.7 and 7.8% in the urban and rural areas, respectively. The prevalence of IGT was 8.8% in urban men and 8.3% in women; the corresponding values for rural men and women were 8.7 and 6.4%. The prevalence of NIDDM increased with age, markedly so in the urban people. The urban-rural difference was significant for NIDDM (chi 2 = 29.4, P less than 0.001) but not for IGT. In the urban population, 65% of the NIDDM patients were known cases, whereas in the rural area, the known cases accounted for only 24%. Bivariate analysis showed an association of BMI, STR, and WHR with prevalence of NIDDM plus IGT. In the multiple logistic regression analysis, age, BMI, STR, and WHR were associated significantly with glucose intolerance in the urban population, whereas only age was significant in the rural population. The best predictors of NIDDM were age, BMI, WHR, and urbanization.

CONCLUSIONS

The study showed a high prevalence of NIDDM in the urban southern Indian population. The prevalence of NIDDM in the same ethnic group in rural areas was significantly lower. The prevalence of IGT was similar in both populations. Upper body adiposity was a significant predictor of NIDDM in this population with low rates of obesity.

Prevalence of childhood diabetes in an urban population in south India

The objective of the study was to estimate the prevalence of insulin-dependent diabetes in children less than or equal to 15 years in an urban area in south India, by a population study. Three zones from the northeastern part of the city demarcated by the Directorate of Census were chosen. Ascertainment of the cases from these zones was made (a) by collecting data from the major hospitals and diabetes clinics by personal visit; (b) by questionnaire sent to medical practitioners in the area; and (c) from the chemists and druggists who sell insulin. Recommendations of the Diabetes Epidemiology Research International Registry Group were used. Thirty children with insulin-dependent diabetes with age at diagnosis less than or equal to 15 years were identified. The prevalence was 0.26/1000. The peak age at diagnosis was 12 years. This first population-based study of prevalence of insulin-dependent diabetes in south India shows that insulin-dependent diabetes is not rare. It is higher than reported from many other Asian countries.

Expression of angiotensin II AT2 receptors in the rat skin during experimental wound healing

We localized and characterized angiotensin II AT1 and AT2 receptors in the skin of 2-week-old rats during experimental wound healing. Both AT1 and AT2 were present in the skin. Three days after wounding, the expression of angiotensin II receptors was significantly enhanced in the dermis as well as in a localized band within the superficial dermis of the skin surrounding the wound. The major proportion of this increase was due to angiotensin II AT2 receptors. Our results suggest a physiological role for AT2 receptors in the process of tissue repair.

Insulin responses to varying hyperglycaemia in newly diagnosed non-insulin dependent diabetic patients

The effect of varying degrees of hyperglycaemia on insulin secretion was studied in newly diagnosed non-insulin dependent diabetic patients, stratified according to the fasting plasma glucose values. Of the 116 patients studied, 62 were non-obese and 54 obese. Insulin response patterns during 2h oral glucose tolerance test were analysed in comparison with the values in weight matched control subjects and also with respect to the degree of hyperglycaemia. The effect of hyperglycaemia on beta cell secretion differed in obese and non-obese patients. In the non-obese, fasting insulin levels were within normal range even in those with severe hyperglycaemia while the corresponding values in response to glucose stimulation showed a decreasing pattern. In obese patients, even fasting immunoreactive insulin (IRI) value was decreased and with increasing hyperglycaemia the reduction in IRI response to glucose stimulation was of greater magnitude compared to non-obese patients. Thus the modulating effect of obesity on insulin secretion appears to disappear with development of hyperglycaemia. The insulinogenic index was low in all the diabetic patients.