High prevalence of NIDDM and impaired glucose tolerance in Indian, Creole, and Chinese Mauritians. Mauritius Noncommunicable Disease Study Group

Mauritius, a multiethnic island nation in the southwestern Indian Ocean, has one of the world's highest diabetes mortality rates. The prevalence of both impaired glucose tolerance (IGT) and non-insulin-dependent diabetes mellitus (NIDDM) was investigated in 5080 Muslim and Hindu Indian, Creole (mixed African, European, and Indian origin), and Chinese Mauritian adults aged 25-74 yr who were selected by random cluster sampling. Based on a 75-g oral glucose tolerance test and World Health Organization criteria, the age-standardized prevalence of IGT was significantly greater in women (19.7%, 95% confidence interval [CI] 18.1-21.2) than in men (11.7%, CI 10.5-12.8). By contrast, the prevalence of NIDDM was similar in men (12.1%, CI 10.9-13.4) and women (11.7%, CI 10.5-12.8) for all ethnic groups combined. The sex difference in IGT prevalence was seen in all ethnic groups, but for NIDDM, the sex difference was not consistent across ethnic groups. However, age- and sex-standardized prevalence of IGT and NIDDM was remarkably similar across ethnic groups (16.2 and 12.4% in Hindu Indians, 15.3 and 13.3% in Muslim Indians, 17.5 and 10.4% in Creoles, and 16.6 and 11.9% in Chinese, respectively). Three new cases of diabetes were diagnosed for every two known cases. The high prevalence of abnormal glucose tolerance in Indian subjects is consistent with studies of other migrant Indian communities, but the findings in Creole and, in particular, Chinese subjects are unexpected. Potent environmental factors shared between ethnic groups in Mauritius may be responsible for the epidemic of glucose intolerance.     

High-resolution analysis of locomotor activity rhythms indisconnected,a visual-system mutant ofDrosophila melanogaster

Free-running locomotor activity and eclosion rhythms ofDrosophila melanogaster, mutant at thedisconnected (disco) locus, are substantially different from the wild-type phenotype. Initial periodogram analysis revealed little or no rhythmicity (Dushayet al., 1989). We have reanalyzed the locomotor activity data using high-resolution signal analysis (maximum-entropy spectral analysis, or MESA). These analyses, corroborated by autocorrelograms, uncovered significant residual circadian rhythmicity and strong ultradian rhythms in most of the animals tested. In this regard thedisco mutants are much like flies expressing mutant alleles of theperiod gene, as well as wild-type flies reared throughout life in constant darkness. We hypothesize that light normally triggers the coupling of multiple ultradian oscillators into a functional circadian clock and that this process is disrupted indisco flies as a result of the neural lesion.This work was supported in part by NIH Grant FM-33205.     

Identification of a new locus for autosomal dominant non-syndromic hearing impairment (DFNA7) in a large Norwegian family

Hereditary hearing impairment affects about 1 in 1000 newborns. In most cases hearing loss is non-syndromic with no other clinical features, while in other families deafness is associated with specific clinical abnormalities. Analysis of large families with non-syndromic and syndromic deafness have been used to identify genes or gene locations that cause hearing impairment. The present report describes a large Norwegian family with autosomal dominant non-syndromic, progressive high tone hearing loss with linkage to 1q21-q23. A maximum LOD score of 7.65 (theta = 0.00) was obtained with the microsatellite marker D1S196. Analysis of recombinant individuals maps the deafness gene (DFNA7) to a 22 cM region between D1S104 and D1S466. The region contains several attractive candidate genes. This report supports the idea of extensive genetic heterogeneity in hereditary hearing impairment and represents the first localization of a deafness gene in a Norwegian family.      

Multiple cerebral metastases: detectability with Gd-DTPA-enhanced MR imaging

Sixteen patients with suspected cerebral metastases were studied with magnetic resonance (MR) imaging before and after the intravenous administration of 0.1 mmol/kg of gadolinium diethylenetriaminepenta-acetic acid. The images were interpreted blindly by two neuroradiologists; all clinical, radiologic (computed tomographic and MR imaging), and pathologic data were reviewed to arrive at a final "best diagnosis," which was then compared with the prior blinded interpretations. Of seven patients found to have multiple metastases, six (86%) had at least one tumor nodule depicted by postinfusion MR imaging that was missed by one or both observers on review of preinfusion images alone. Lesions missed on preinfusion studies were usually small nodules hidden by or not detected next to regions of high-signal edema thought to be related to the adjacent tumor nodule. The authors believe that contrast enhancement improves detection of metastatic foci with MR imaging and that the findings indicate broader implications for the detection of multiple lesions from other causes.     

CLINICO-EPIDEMIOLOGICAL ALGORITHM FOR PREDICTING SYSTEMIC ARTERIAL HYPERTENSION AT HIGH ALTITUDE THROUGH MATHEMATICAL MODELLING

A population based hybrid design combining element of cohort and cross-sectional approach was used to develop a simple clinical algorithm to predict individual probability of developing hypertension (systolic BP > 140 mm Hg and/or diastolic BP > 90 mmHg). 3615 soldiers initially normotensive at the time of induction into high altitude, were studied by systematic random sampling. Multiple logistic regression analysis showed a high significant association between hypertension and age, body mass index (BMI), tobacco smoking and alcohol consumption. Using the constant/coefficient values obtained from the logistic model and the receiver operating characteristics (ROC) curve analysis, the following predictive rule was developed – To the age in years, add (BMIx 3.86); also add 5.53 if he is a smoker; and add 19.81 if he consumes alcohol. If the total exceeds 142, the individual is at high risk of developing hypertension. This algorithm carries a sensitivity of 68.2% and specificity of 78.5%.KEY WORDS: Hypertension, High altitude     

The relation of physical activity to cardiovascular disease risk factors in Mauritians. Mauritius Noncommunicable Disease Study Group

The authors investigated the relation between physical activity and cardiovascular disease risk factors in a random sample of 4,658 Asian Indian, Creole, and Chinese adults aged 25-74 years from the island nation of Mauritius. Subjects known to have diabetes were excluded from analyses. Subjects were divided into "active" and "inactive" groups on the basis of a combined leisure and occupational physical activity score determined at interview (April 1987). Two-hour plasma glucose concentration and fasting and 2-hour serum insulin concentrations were significantly lower and high density lipoprotein (HDL) cholesterol was significantly higher in active subjects of both sexes. Plasma uric acid and fasting triglyceride levels were also lower among active subjects, but significantly so only in females. Systolic and diastolic blood pressure levels, body mass index (weight (kg)/height (m)2), and waist:hip ratio varied little between the two activity groups. In multiple linear regression analyses, physical activity made an independent negative contribution to the models for 2-hour glucose and insulin in both males and females, as well as for fasting insulin in males. When glucose and insulin were not included, physical activity also made an independent contribution to the models for plasma triglycerides (inversely) in females and HDL cholesterol and HDL cholesterol as a proportion of total cholesterol (positively) in males. The authors have demonstrated improved cardiovascular disease profiles associated with physical activity in Mauritians. The data suggest that much of the effect is modulated via an effect on insulin-glucose metabolism. Promotion of exercise should become an important strategy in the prevention of cardiovascular disease and glucose intolerance in this population.