Enhanced complement activation is part of the unfavourable cardiovascular risk profile in South Asians

South Asian immigrants in western societies exhibit a high burden of diabetes and subsequent vascular complications. Diabetic vascular complications are associated with vascular inflammation. We hypothesize that enhanced complement activation is involved. Therefore, levels of complement C3 and SC5b-9 - the soluble end product of complement activation - in a group of 200 South Asians were compared with an age- and sex-matched control group of native Caucasians. In addition, the association between complement levels and albuminuria, an indicator of renal damage and a cardiovascular risk marker, was assessed in the diabetic South Asian group. Compared with native Caucasians, South Asians had significantly higher levels of both serum C3 and plasma SC5b-9, even when only non-diabetic South Asians were considered. Diabetic South Asians had significantly higher C3 levels compared with non-diabetic South Asians. In diabetic South Asians, higher levels of SC5b-9 were associated with an increased prevalence of albuminuria (odds ratio 5.4, 95% confidence interval 1.8-15.8). These results suggest that enhanced complement activation is part of the unfavourable cardiovascular risk profile in South Asians.

Lower frequency of the 5/5 homozygous CNDP1 genotype in South Asian Surinamese

We investigated the frequency of the 5/5 homozygous CNDP1 (carnosinase) genotype, which was found to be associated with a reduced risk of developing diabetic nephropathy, in three ethnic groups in The Netherlands. Particularly interesting were the South Asian Surinamese, who have a high prevalence of diabetic nephropathy. Furthermore, we investigated the association between this gene and carnosinase activity in South Asian Surinamese and whether carnosinase was expressed in the kidney. We genotyped 290 South Asian Surinamese, 532 African Surinamese, and 472 White Dutch in a cross-sectional population study. Furthermore, an independent cohort of South Asian Surinamese was genotyped. In this population, carnosinase activity was measured in serum. Immunostaining and in situ hybridization for CNDP1 were performed on kidney tissue. Both South Asian populations had lower frequencies of the 5/5 homozygous genotype than African Surinamese and White Dutch (23.0%, 27.2%, 38.2%, and 41.3%, respectively; chi-square, p<0.001). This genotype showed a lower carnosinase activity in South Asian Surinamese (Wilcoxon rank-sum, p=0.03). CNDP1 was expressed in the kidney. South Asian Surinamese have a lower frequency of the 5/5 homozygous genotype, which was associated with lower carnosinase activity. Our study provides an indication that South Asian Surinamese are genetically at risk for developing diabetic nephropathy.

Renal disease in relatives of Indo-Asian Type 2 diabetic patients with end-stage diabetic nephropathy

AIMS/HYPOTHESIS

Indo-Asian immigrants in The Hague, The Netherlands, have a nearly 40-fold higher risk of end-stage diabetic nephropathy compared to the Caucasian population. To detect a genetic susceptibility for nephropathy within the Indo-Asian population, we assessed whether familial clustering of nephropathy occurs in families of Indo-Asian Type 2 diabetic patients.

METHODS

We compared nephropathy prevalence between two groups of first-degree relatives of Indo-Asian patients with Type 2 diabetes; the first group (case relatives) consisted of 169 relatives of patients with end-stage diabetic nephropathy; the second group (control relatives) consisted of 161 relatives of diabetic patients who had no nephropathy. The case and control relatives were examined for diabetes, blood pressure, renal function, microalbuminuria and urine dipstick measurements.

RESULTS

The mean age was 41 years and similar in the case and control relatives. Diabetes was distributed equally in both family groups. We did not find more nephropathy in first-degree relatives of Indo-Asian Type 2 diabetic patients with end-stage diabetic nephropathy in comparison with the control-relatives.

CONCLUSION/INTERPRETATION

We could not detect a genetic susceptibility for diabetic nephropathy within the Indo-Asian population. The lack of familial clustering of renal disease in Indo-Asian diabetic patients points to a general genetic or environmental susceptibility for diabetic nephropathy in this population.

Increased end-stage diabetic nephropathy in Indo-Asian immigrants living in the Netherlands

AIMS/HYPOTHESIS

We aimed to investigate the risk of end-stage diabetic nephropathy due to Type II (non-insulin-dependent) diabetes mellitus in Indo-Asian immigrants from Surinam.

METHODS

A demographically based case-control study was carried out in Surinamese Indo-Asian immigrants and Dutch Caucasian subjects. All patients with end-stage diabetic nephropathy who had started dialysis between 1990 and 1998 were identified through a national registry of all patients entering a renal replacement program in the Netherlands. The general population of native Dutch and Surinamese Indo-Asians were considered the control subjects.

RESULTS

Among Indo-Asian immigrants, the age adjusted relative risk of end-stage diabetic nephropathy was 38 (95 % CI 16 to 91) compared with the native Dutch population. The duration of diabetes until the start of dialysis treatment was similar in both ethnic groups, about 17 years.

CONCLUSION/INTERPRETATION

The Indo-Asian subjects had a nearly 40-fold increase in the risk for end-stage diabetic nephropathy due to Type II diabetes, compared with the native Dutch population. This was higher than expected on the basis of the eightfold higher prevalence of diabetes in the Indo-Asian population. The similar duration of diabetes until the start of dialysis treatment in both ethnic groups supports the hypothesis of a higher incidence of diabetic nephropathy in the Indo-Asian diabetic population. Early and frequent screening for diabetes and microalbuminuria is recommended in Indo-Asian subjects.

Food choice in hyperthyroidism: potential influence of the autonomic nervous system and brain serotonin precursor availability

We explored energy and macronutrient intake in patients with Graves' hyperthyroidism. We specifically hypothesized that hyperthyroidism is associated with increased appetite for carbohydrates, because of enhanced sympathetic tone and diminished serotonin mediated neurotransmission in the brain. To test this hypothesis, we measured food intake by dietary history and food selected for lunch in the laboratory in 14 patients with Graves' hyperthyroidism. Twenty-four-hour catecholamine excretion was used as a measure of activity of the sympathetic nervous system (SNS) and the plasma [Trp]/[NAA] ratio was measured to estimate (rate limiting) precursor availability for brain 5-hydroxytryptamine synthesis. All measurements were repeated after the subjects had been treated to establish euthyroidism. In addition, the effects of nonselective beta-adrenoceptor blockade upon these parameters were studied to evaluate the influence of beta-adrenergic hyperactivity on food intake. Hyperthyroidism was marked by increased SNS activity and reduced plasma [Trp]/[NAA] ratio. Accordingly, energy intake was considerably and significantly increased in hyper vs. euthyroidism, which was fully attributable to enhanced carbohydrate consumption, as protein and fat intake were not affected. These results suggest that hyperthyroidism alters the neurophysiology of food intake regulation. Increased SNS activity and reduced Trp precursor availability for 5-hydroxytryptamine synthesis in the brain may drive the marked hyperphagia and craving for carbohydrates that appears to characterize hyperthyroid patients. Because propranolol did not affect food intake in hyperthyroidism, the potential effect of catecholamines on food intake might be mediated by alpha-adrenoceptors.

[The thrombosis service as a source of information for studies in patients with heart valve prostheses]

A new study design was evaluated for the estimation of the incidence of thromboembolic complications, bleeding complications and endocarditis in patients with prosthetic heart valves. Thromboembolism is a serious complication in patients with artificial heart valves. Consequently lifelong anticoagulation therapy is indicated for such patients. In the Netherlands the intensity of the anticoagulation is monitored by a network of regional anticoagulation services. The computerized patient information system of the Leiden anticoagulation service was used for a two year follow-up study of patients with mechanical heart valves. In these years anticoagulation was monitored in 273 patients with a total follow-up period of 442 patient-years. The incidence figures for thromboembolism, bleeding complications and endocarditis were 0.9/100 patient-years, 5.6/100 patient-years and 0.2/100 patient-years, respectively. The findings are similar to those of classical follow-up studies. This method is not suitable for detection of the direct early postoperative mortality or for follow-up of patient with heterografts. We conclude that the detection and follow-up by means of regional anticoagulation service offers an opportunity to investigate patients with mechanical heart valves in an efficient way without notable selection.