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A histochemical study of muscle in club foot.

A histochemical analysis was made of 103 muscle biopsies taken from 62 patients with idiopathic club feet. Any reduction in the diameter of the muscle fibres associated with wasting of the calf muscle was recorded. Histochemical abnormalities existing in these biopsies were revealed by comparison with normal biopsies obtained from the normal legs of 13 children with unilateral deformities. No significant difference was found between the diameter of the muscle fibres taken from normal and affected legs aged under six months. This indicates that wasting of the calf muscle is due to a reduction in the number of fibres rather than their size. The muscle structure was normal excluding denervation and reinnervation. The soleus muscle in patients aged under six months contained 61 per cent Type 1 fibres in the affected legs, compared to 44.3 per cent in normal legs. Similar values were found in the normal and abnormal tibialis posterior muscles, long flexors of the toe and peroneal muscles. The change in composition of the soleus muscle and the reduction in the number of fibres may be caused by a defective neural influence on the development of the limb in club foot.

Adolescent↗

Indonesian mitochondrial DNA and its opposition to a Pleistocene era origin of proto-Polynesians in island southeast Asia.

The origin of modern Polynesians, the route of their expansion into the Pacific Ocean, and the timing of their movements all remain contentious topics in modern anthropology. Numerous studies have used molecular data to elucidate settlement patterns in the Indo-Pacific region, but the same evidence is often interpreted in opposing ways by different researchers. Above all, mitochondrial DNA (mtDNA) diversity has been used to discriminate between competing migration models and has narrowed the probable source of proto-Polynesian peoples to southern China and Taiwan or eastern Indonesia. Richards et al. (1998) used a dating method employing the p statistic to argue for an origin of Polynesian peoples in eastern Indonesia during the Pleistocene (> 10,000 years ago). Here, the time to the most recent common ancestor (TMRCA) is recalculated for a new series of Indonesian mtDNA sequences with Polynesian affinities. These data, which incorporate additional sequences published after 1998, produce dates that cannot rule out the possibility of a common ancestor for these sequences during the Holocene (< 10,000 years ago). This implies that previous estimates of TMRCA dates for Indonesian sequences lacked the statistical robustness necessary for replicability. The extant mtDNA evidence can no longer be viewed as favoring a Polynesian origin in eastern Indonesia, but instead remains consistent with an origin of proto-Polynesian peoples in southern China and Taiwan.

Asia, Southeastern↗

Genetic diversity and linkage disequilibrium in the Polynesian population of Niue Island.

Isolated populations that recently have been derived from small homogeneous groups of founders should have low genetic diversity and high levels of linkage disequilibrium and should be ideal for mapping ancestral polymorphisms that influence complex genetic disease susceptibility. Populations that fulfill these criteria have been difficult to identify. We have been looking for Polynesian populations with these characteristics, because Polynesians have high rates of complex genetic diseases. In Niue Islanders all ancestral female (mitochondrial HSVI sequence) and 90.4% of ancestral male (Y-chromosome haplogroup) lineages are of Southeast Asian origin. The frequency of European Y-chromosome haplogroups is 7.2%. The diversities of mitochondrial HSV1 sequences (h = 0.18 +/- 0.05) and Y-chromosome haplo-groups (h = 0.18 +/- 0.05) are lower than values published for any other population. Ten autosomal microsatellites spaced over 5.8 cM show low allele numbers in Niue Islanders relative to Europeans (55 vs. 88 total alleles, respectively) and a modest reduction in heterozygous loci (0.71 +/- 0.02 vs. 0.78 +/- 0.02, p = 0.04). The higher linkage disequilibrium (d2) between these loci in Niue Islanders relative to Europeans (p = 0.001) is negatively correlated (r = -0.47, p = 0.01) with genetic distance. In summary, Niue Islanders are genetically isolated and have a homogeneous Southeast Asian ancestry. They have reduced autosomal genetic diversity and high levels of linkage disequilibrium that are consistent with the influence of genetic drift mechanisms, such as a founder effect or bottlenecks. High-powered linkage disequilibrium studies designed to map ancestral polymorphisms that influence complex genetic disease susceptibility may be feasible in this population.

DNA, Mitochondrial↗

Traces of archaic mitochondrial lineages persist in Austronesian-speaking Formosan populations.

Genetic affinities between aboriginal Taiwanese and populations from Oceania and Southeast Asia have previously been explored through analyses of mitochondrial DNA (mtDNA), Y chromosomal DNA, and human leukocyte antigen loci. Recent genetic studies have supported the "slow boat" and "entangled bank" models according to which the Polynesian migration can be seen as an expansion from Melanesia without any major direct genetic thread leading back to its initiation from Taiwan. We assessed mtDNA variation in 640 individuals from nine tribes of the central mountain ranges and east coast regions of Taiwan. In contrast to the Han populations, the tribes showed a low frequency of haplogroups D4 and G, and an absence of haplogroups A, C, Z, M9, and M10. Also, more than 85% of the maternal lineages were nested within haplogroups B4, B5a, F1a, F3b, E, and M7. Although indicating a common origin of the populations of insular Southeast Asia and Oceania, most mtDNA lineages in Taiwanese aboriginal populations are grouped separately from those found in China and the Taiwan general (Han) population, suggesting a prevalence in the Taiwanese aboriginal gene pool of its initial late Pleistocene settlers. Interestingly, from complete mtDNA sequencing information, most B4a lineages were associated with three coding region substitutions, defining a new subclade, B4a1a, that endorses the origin of Polynesian migration from Taiwan. Coalescence times of B4a1a were 13.2 +/- 3.8 thousand years (or 9.3 +/- 2.5 thousand years in Papuans and Polynesians). Considering the lack of a common specific Y chromosomal element shared by the Taiwanese aboriginals and Polynesians, the mtDNA evidence provided here is also consistent with the suggestion that the proto-Oceanic societies would have been mainly matrilocal.

Asian People↗

Mucociliary transport and ultrastructural abnormalities in Polynesian bronchiectasis.

Ciliated bronchial or nasal epithelium from 20 Polynesian bronchiectatic patients was examined in an electron microscope. In all patients there was a partial or complete loss of dynein arms. Also, in many patients other ciliary abnormalities were present with a high proportion, often over 25%, of cilia affected. This contrasts with a control group where ciliary abnormalities were infrequent. Mucociliary clearance, measured by imaging 99mTc sulfide dust with a gamma camera, was either absent or markedly reduced in these bronchiectatic patients.

Bronchi↗

Spirometry and maximal expiratory flow-volume curve reference standards for Polynesian, European, and Chinese teenagers.

Lung function was compared and reference standards were determined in 1,007 Polynesian, European, and Chinese teenagers attending school in Tahiti (517 boys, 490 girls; mean age, 14.4 years). Spirometric study results and maximal expiratory flow-volume curves were measured using techniques recommended by the American Thoracic Society. Age, standing height, and weight were chosen as the independent variables for males, and age and standing height for females. Regression equations constructed with logarithmically transformed dependent variables provided accurate predictions. We observed significant racial differences: in the Europeans, forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were higher than the mean values predicted for the whole study population, while forced expiratory flow during the middle half of the FVC (FEF25-75%) and maximal expiratory flows after 25, 50, and 75 percent of FVC had been exhaled (V max 25, 50, and 75, respectively) were about equal to the mean values; in the Polynesians, volumes and flows were mostly lower than the mean; in the Chinese, FVC in boys and girls, and FEV1 in girls only, were lower, while the other flows were higher. The FEV1/FVC, FEF25-75%/FVC, Vmax25/FVC, Vmax50/FVC, and Vmax75/FVC were significantly higher than the mean in the Chinese boys and girls and often lower in the Europeans.

Adolescent↗

Blood pressure, obesity and urine cation excretion in two populations of the Cook Islands.

As part of a physical anthropological and linguistic research in the Cook Islands, blood pressure levels, the degree of obesity, and urine cation excretion were measured in the residents of Rarotonga (the most westernized) and Mangaia (a less westernized island) in 1986. The rise of blood pressure with age was observed in both sexes in each island, with the mean systolic pressures of the oldest male group (155.8 vs. 137.3 mmHg) significantly higher, and those of older female groups (137.4 vs. 127.1 and 154.7 vs. 145.9 mmHg) relatively higher in Rarotonga than in Mangaia. The mean body mass index was much the same between the two islands, but mean skinfolds at triceps and subscapular sites were thicker in Rarotonga than in Mangaia in each sex and age group. The mean sodium to potassium excretion ratio fell with age (2.97 to 0.94 in males, 2.24 to 1.09 in females) in Rarotonga, and was consistently low (1.09 to 0.73) in Mangaia. Body mass index correlated with both systolic and diastolic pressures in each sex and island group but indeces of sodium excretion did not. Obesity was considered a more important risk factor for hypertension than sodium-intake in the surveyed population, and skinfolds, related to daily physical activity, probably associated with the difference in blood pressure levels observed between the two islands.

Adolescent↗

Hedruris hanleyae n. sp. (Nematoda: Hedruridae) from Hemidactylus garnotii (Sauria: Gekkonidae) from the Cook Islands, Oceania.

Hedruris hanleyae n. sp. (Nematoda: Hedruridae) from the stomach of Hemidactylus garnotii collected in 1989 on Atiu, Cook Islands is described and illustrated. Hedruris hanleyae n. sp. represents the 21st species to be assigned to the genus and is distinguished from other oriental species by the distribution pattern of caudal papillae of the male: 10 pairs posterior subventral papillae; 2 pairs precloacal and 8 pairs postcloacal.

Animals↗

Multivariate prediction of total and cardiovascular mortality in an obese Polynesian population.

The effects of body weight and blood pressure on the risk of total mortality and mortality from cardiovascular diseases (CVD) were examined in a prospective sample of 5,866 adult residents of American Samoa, a Polynesian population noted for exhibiting high levels of obesity. Data collected during 1975-76 were linked to mortality records from 1976 through 1981. In logistic regression models which did not include blood pressure, percent of desirable weight was an important risk factor for mortality from CVD, but it was not an important risk factor when diastolic blood pressure was included in the model. Percent of desirable weight was not related to mortality from all causes combined in either Samoan men or women. Age and diastolic blood pressure were predictors of total and CVD mortality in men and women. These results, in an obese population, suggest that body weight and obesity are not independently related to excess mortality in the very obese, although they may associate with high blood pressure. These results also suggest that relations between physiological characteristics and mortality may vary with cultural, genetic, or other factors not examined in this study.

Adult↗

Diabetes mellitus in an urbanized, isolated Polynesian population. The Funafuti survey.

An epidemiologic study of diabetes in the urbanized Polynesian population of Funafuti has established a prevalence of 8 per cent in subjects aged 10 years and over. Of these, 0.9 per cent were known diabetics, and the remainder were diagnosed on the basis of a plasma glucose level of at least 160 mg./100 ml. two hours after a 75 gm. glucose load. A further 5.9 per cent had borderline diabetes as judged by a two-hour postload plasma glucose of 140-159 mg./100 ml. In those aged 20 years and over, the prevalence of diabetes was 10.1 per cent, similar to that reported in other acculturated Polynesian groups. The prevalence of both borderline diabetes and frank diabetes was twice as high in the females as in males. This difference appeared to be related to the greater degree of obesity in the females, but the prevalence was not related to parity. The increase in frequency of diabetes among these islanders coincides with a change of traditional island life style to that of urbanized Western populations. The results suggest that there may be 10 times the actual number of known diabetics in some Pacific populations.

Adolescent↗

Ethnic variability in the plasma insulin response to oral glucose in Polynesian and Micronesian subjects.

The pattern of insulin response to oral glucose over a wide range of glucose tolerance has been studied in two separate ethnic groups--Polynesians and Micronesians. Fasting insulin concentrations were relatively unchanged over the entire range of glucose tolerance in both populations, irrespective of whether comparable lean or obese samples of both groups were studied. The patterns of 2-h plasma insulins were similar over the whole range of glucose tolerance in Polynesians and Micronesians. However, in the comparisons of all subjects, or lean or obese groups of these populations, the plasma insulin concentrations of the Micronesians were both consistently and significantly higher. As the data analysis was arranged to take into account groups with identical 2-h plasma glucose concentrations and comparable degrees of obesity, the differences cannot be attributed to differences in the glucose levels or in obesity. In the presence of similar fasting insulin concentrations, these findings imply an ethnic variability in the pancreatic beta-cell response to oral glucose.

Adolescent↗

Relationship between prevalence of impaired glucose tolerance and NIDDM in a population.

OBJECTIVE: To study the relationship between the prevalence of impaired glucose tolerance (IGT) and non-insulin-dependent diabetes mellitus (NIDDM) across populations of the Pacific Ocean region to assess whether variability in those two proportions followed some predictable pattern related to modernization of life-style and risk factor levels. RESEARCH DESIGN AND METHODS: Prevalence estimates from studies with 75-g oral glucose loads and World Health Organization criteria were age standardized. RESULTS: The linear correlation between IGT and NIDDM prevalence was poor (0.22 in men and 0.24 in women), although it was improved when the outlying data of Micronesian Nauruans and Australian Aborigines were excluded (r = 0.65, P less than 0.01 in men and r = 0.54, P less than 0.01 in women). However, an epidemicity index calculated as the percentage of total glucose intolerance (TGI) made up by IGT (i.e., IGT/TGI) had the strongest correlation with NIDDM prevalence (r = -0.81, P less than 0.001 in men and r = -0.77, P less than 0.001 in women) and also explained more of its variance, with no population having undue influence on the relationship. When IGT/TGI was plotted against NIDDM prevalence for the genetically homogeneous rural (relatively traditional) and urban (modernized) segments of five Pacific island populations, there was a clear tendency for IGT/TGI to decline as the prevalence of NIDDM increased in association with worsening risk factor levels. However, longitudinal data for the high prevalence population of Nauru demonstrated that at least in a stabilizing epidemic, changes in the prevalence of IGT and NIDDM may not be easily predictable. CONCLUSIONS: The epidemicity index may be useful as an indicator of the potential for higher future NIDDM prevalence in whole populations. Populations will probably equilibrate at a certain NIDDM prevalence dependent on the strength of their genetic susceptibility to the disease and their degree of exposure to adverse environmental risk factors, including modern diet, physical inactivity, and obesity.

Adult↗

Diabetic nephropathy and microalbuminuria in the community. The South Auckland Diabetes Survey.

OBJECTIVE: To compare the clinical, anthropometric, and metabolic characteristics of New Zealand Europeans, Maori, and Pacific Islanders with non-insulin-dependent diabetes mellitus (NIDDM) with emphasis on risk factors for the development of diabetic nephropathy. RESEARCH DESIGN AND METHODS: A cross-sectional survey of 555 (74% of 750 available) diabetic patients attending diabetes clinics and randomly selected primary care centers was conducted in Auckland, New Zealand. RESULTS: Among those with NIDDM, Maori and Pacific Islanders were younger at diagnosis, more obese, and had poorer glucose control when compared with the Europeans (fructosamine in mumol/l: Maori 335 +/- 78, Pacific Islanders 367 +/- 90, Europeans 318 +/- 55; overall P < 0.001). Systolic blood pressure (sBP) was higher in Maori (145 +/- 31 mmHg) and lower in Pacific Islanders (135 +/- 25 mmHg) when compared with Europeans (141 +/- 25 mmHg; overall P < 0.005). Mean estimated daily urinary albumin excretion (UAE) was 18.2 (15.5-1.3) mg/day in Europeans, 94.8 (60.5-148.7) mg/day in Maori, and 44.2 (32.3-60.3) mg/day in Pacific Islanders. The prevalence of proteinuria and end-stage renal failure were also higher in Maori and Pacific Islanders. The excess prevalence of microalbuminuria and proteinuria in Maori was present within 5 years of diagnosis. Europeans with impaired renal function were least likely to have associated proteinuria or microalbuminuria. Microalbuminuria and nephropathy were not consistently associated with either higher blood pressure or worse glucose control. CONCLUSIONS: NIDDM in Maori and Pacific Islanders is associated with a greater degree of proteinuria and end-stage renal failure than that in Europeans. This observation is not explained by conventional risk factors.

Adolescent↗

High prevalence of diabetic retinopathy and nephropathy in Polynesians of Western Samoa.

OBJECTIVE: To determine the prevalence of diabetic retinopathy and nephropathy retinopathy and nephropathy and to define associated risk factors in Polynesian Western Samoans with non-insulin-dependent diabetes mellitus (NIDDM) or impaired glucose tolerance (IGT). RESEARCH DESIGN AND METHODS: A 1991 population-based study in Samoan adults (ages 25-74 years) included a 75-g oral glucose tolerance test, anthropometric measurements, and blood pressure recordings. Subjects with NIDDM or IGT had 45-degree stereo photographs taken (n = 263) (three standard fields of the right eye), and retinopathy was graded in comparison with Airlie House photographs. First-morning urine samples (n = 304) were also collected from these subjects and from a subsample with normal glucose tolerance. Urinary albumin concentration (UAC) was measured by radioimmunoassay: microalbuminuria was defined as UAC of 30-299 micrograms/ml; and macroalbuminuria among subjects with Proliferative diabetic retinopathy was found in 4.5% of known diabetic subjects. The prevalence of elevated UAC was 15.0% in subjects with IGT, 26.0% in newly diagnosed diabetes subjects, and 23.4% in known diabetes subjects. For all diabetic subjects (n = 162), the factors independently associated with diabetic retinopathy (logistic regression) were duration of diabetes, fasting plasma glucose, and body mass index (inversely). Duration of diabetes, serum triglyceride concentrations, and systolic blood pressure were independently associated with elevated UAC in all diabetic subjects (n = 138), and fasting plasma glucose had borderline significance. CONCLUSIONS: Diabetic retinopathy and albuminuria are common in Polynesian Western Samoans. Duration of diabetes and level of glycemia were the most important associated factors. These data underline the need for cost-effective programs for the detection and early treatment of diabetes in Western Samoa and other developing populations with high susceptibility to NIDDM.

Adult↗

Use of insulin pumps in pregnancies complicated by type 2 diabetes and gestational diabetes in a multiethnic community.

OBJECTIVE: To describe the use of insulin pump therapy in women with gestational diabetes mellitus (GDM) or type 2 diabetes in pregnancy and persistent hyperglycemia despite multiple injections of subcutaneous insulin. RESEARCH DESIGN AND METHODS: As part of a service audit, deliveries to women with diabetes at a single South Auckland hospital were reviewed from 1991 through 1994. Glycemic control was estimated by the mean of self-recorded and laboratory postprandial glucose concentrations. In a nested case-control study, pregnancies complicated by GDM/type 2 diabetes with use of an insulin pump were compared with those without insulin pump therapy and peak insulin requirements of 100-199 units/ day, matched for ethnicity and type of diabetes. RESULTS: A total of 30 of 251 Polynesian, European, and South Asian women with singleton pregnancies complicated by insulin-requiring GDM/type 2 diabetes used an insulin pump. An additional two women with high insulin requirements discontinued pump therapy. None of the women with GDM/type 2 diabetes experienced severe hypoglycemia, whereas 79% of the women had improved glycemic control within 1-4 weeks. Mothers using a pump had greater insulin requirements (median maximum 246 vs. 130 units per day) and greater weight gain (10.6 vs. 5.0 kg). Their babies were more likely to be admitted to the Special Care Baby Unit but were neither significantly heavier nor experienced greater hypoglycemia than control subjects. CONCLUSIONS: Insulin pump therapy seems to be safe and effective for maintaining glycemic control in pregnancies complicated by GDM/type 2 diabetes and requiring large doses of insulin.

Adult↗