Minato Nakazawa

FTO polymorphisms in oceanic populations

AbstractIt has been suggested that Neels “thrifty genotype” model may account for high body weights in some Oceanic populations, which presumably arose in modern times. In European populations, common variants (rs1421085-C, rs17817449-G, and rs9939609-A) in the fat mass and obesity (FTO associated) were recently found to be associated with body mass index (BMI) or obesity. In this study, we investigated the population frequencies of these variants in six Oceanic populations (Melanesians, Micronesians, and Polynesians) and tested for an association with BMI. Unlike European populations, the Oceanic populations displayed no significant association between the FTO polymorphisms and BMI. These variants were in strong linkage disequilibrium. The population frequencies ranged between 4.2 and 30.3% in the six Oceanic populations, and were similar to those in southeast and east Asian populations. Our study of the FTO polymorphisms has generated no evidence to support the thrifty genotype hypothesis for Oceanic populations.

Gene Flow and Natural Selection in Oceanic Human Populations Inferred from Genome-Wide SNP Typing

It is suggested that the major prehistoric human colonizations of Oceania occurred twice, namely, about 50,000 and 4,000 years ago. The first settlers are considered as ancestors of indigenous people in New Guinea and Australia. The second settlers are Austronesian-speaking people who dispersed by voyaging in the Pacific Ocean. In this study, we performed genome-wide single-nucleotide polymorphism (SNP) typing on an indigenous Melanesian (Papuan) population, Gidra, and a Polynesian population, Tongans, by using the Affymetrix 500K assay. The SNP data were analyzed together with the data of the HapMap samples provided by Affymetrix. In agreement with previous studies, our phylogenetic analysis indicated that indigenous Melanesians are genetically closer to Asians than to Africans and European Americans. Population structure analyses revealed that the Tongan population is genetically originated from Asians at 70% and indigenous Melanesians at 30%, which thus supports the so-called Slow train model. We also applied the SNP data to genome-wide scans for positive selection by examining haplotypic variation and identified many candidates of locally selected genes. Providing a clue to understand human adaptation to environments, our approach based on evolutionary genetics must contribute to revealing unknown gene functions as well as functional differences between alleles. Conversely, this approach can also shed some light onto the invisible phenotypic differences between populations.

The Hair-Organ Relationship in Mercury Concentration in Contemporary Japanese

The hair-organ relationship of mercury concentration was investigated in 46 autopsy samples in Tokyo, Japan. Hair mercury levels were highly significantly correlated with organ Hg levels in the cerebrum, cerebellum, heart, spleen, liver, kidney cortex, and kidney medulla, when the total mercury or methyl mercury value in the organ was compared with the hair total mercury or organic mercury, respectively. When the inorganic mercury value was tested, significant correlations remained, with weaker coefficients in all the organs but the spleen. Stepwise multiple regression analysis evidenced that the hair organic mercury value was the major explanatory variable for the organ total mercury or organ methyl mercury value in all the organs. To explain the organ inorganic mercury value, the hair organic mercury value was the major variable for the cerebrum and kidney (both cortex and medulla), the hair inorganic mercury value was the major variable for the cerebellum and heart, and the hair phosphorous and hair organic mercury were the major variables for the liver; no explanatory variable existed for the spleen. Auxiliary explanatory variables accounted for the organ total mercury and inorganic mercury levels, among which the hair selenium value was conspicuous with negative regression coefficients.

Lack of significantly positive correlations between elemental concentrations in hair and in organs.

Elemental concentrations (Ca, Cu, Fe, Mg, P, Se and Zn) in the hair of Japanese were examined in relation to those in internal organs (cerebrum, cerebellum, heart, spleen, liver, kidney and rib). No significantly positive correlation was found between elemental concentration in hair and that in internal organ. This result indicates the restricted use of hair as a medium for the estimation of nutritional status of the essential elements examined in the present study, at least on an individual basis. The correlations between the concentrations in organs are also presented.

Health status and lifestyle factors as predictors of depression in middle-aged and elderly Japanese adults: a seven-year follow-up of the Komo-Ise cohort study.

BackgroundDepression is a common mental disorder. Several studies suggest that lifestyle and health status are associated with depression. However, only a few large-scale longitudinal studies have been conducted on this topic.MethodsThe subjects were middle-aged and elderly Japanese adults between the ages of 40 and 69 years. A total of 9,650 respondents completed questionnaires for the baseline survey and participated in the second wave of the survey, which was conducted 7 years later. We excluded those who complained of depressive symptoms in the baseline survey and analyzed data for the remaining 9,201 individuals. In the second-wave survey, the DSM-12D was used to determine depression. We examined the risks associated with health status and lifestyle factors in the baseline survey using a logistic regression model.ResultsAn age-adjusted analysis showed an increased risk of depression in those who had poor perceived health and chronic diseases in both sexes. In men, those who were physically inactive also had an increased risk of depression. In women, the analysis also showed an increased risk of depression those with a BMI of 25 or more, in those sleeping 9 hours a day or more and who were current smokers. A multivariate analysis showed that increased risks of depression still existed in men who had chronic diseases and who were physically inactive, and in women who had poor perceived health and who had a BMI of 25 or more.ConclusionsThese results suggest that lifestyle and health status are risk factors for depression. Having a chronic disease and physical inactivity were distinctive risk factors for depression in men. On the other hand, poor perceived health and a BMI of 25 or more were distinctive risk factors for depression in women. Preventive measures for depression must therefore take gender into account.

An Acute Mercuric Mercury Poisoning: Chemical Speciation of Hair Mercury Shows a Peak of Inorganic Mercury Value

A woman ingested a dose of sublimate (approximately 0.9 g) in an attempted suicide. She survived and recovered in response to a combination of therapies including chelate (BAL) therapy, plasma exchange, haemodialysis and peritoneal dialysis. Serum inorganic mercury concentration, urinary inorganic mercury excretion and hair inorganic and organic mercury and selenium concentrations, along the length from the scalp to the distal part, were measured. Longitudinal analysis of hair, revealed a peak in inorganic mercury corresponding to the time of mercury ingestion. Organic mercury and selenium in the hair had different patterns of longitudinal variation from that of inorganic mercury. The biological half-life (23.5 d) of serum inorganic mercury levels was in good agreement with values previously reported in the literature.

Interrelationship between the concentrations of some elements in the organs of Japanese with special reference to selenium-heavy metal relationships.

Multi-element analyses were conducted on internal organs (cerebrum, cerebellum, heart, spleen, liver and kidney) of Japanese obtained from 45 forensic medical autopsy cadavers. Elements analyzed and analytical methods were as follows: Ca, Cd, Cu, Fe, K, Mg, Na, P and Zn by inductively coupled plasma atomic emission spectrometry; total Hg (T-Hg) and inorganic Hg (I-Hg) by cold vapour atomic absorption spectrometry; methyl Hg (MeHg) by gas chromatography; and Se by fluorometry. A significantly positive correlation between Se and T-Hg was observed in kidney, liver, heart and spleen. The T-Hg/Se molar ratio was less than 1 in all the organs examined. The correlation between Zn and Cd was significant in liver and kidney. Multiple regression analyses using Se as a dependent and I-Hg, MeHg, Zn, Cd, Cu as independent variables were conducted on each organ. Inorganic Hg was a significant independent variable in kidney, whereas in liver and spleen it was MeHg. Cadmium was significant in explaining the variations in Se in liver and kidney medulla, indicating Cd-Se co-accumulation in humans.

Can an individualized and comprehensive care strategy improve urinary incontinence (UI) among nursing home residents

Urinary incontinence (UI) is one of the most common and distressing conditions among nursing home residents. Although scheduled care is usually provided for them, incontinence care should be individualized regarding going to the toilet, changing diapers, and taking food and water. We have developed an individualized and comprehensive care strategy to address the problem. We conducted an intervention study that involved training chiefs of staffs, who in turn trained other staffs, and encouraging residents. A total of 153 elderly subjects selected from 1290 residents in 17 nursing homes were eligible to receive our individualized and comprehensive care. The goals of the care strategy were (i) to complete meal intake; (ii) to take fluids up to 1500 ml/day; (iii) to urinate in a toilet; (iv) to spend over 6h out of bed; and (v) to reduce time spent in wet diapers. We explained the aims of our strategy to the chiefs of staff of each nursing home and instructed them to encourage residents to take an active part in our individualized and comprehensive care strategy for 12 weeks. For 3 days before and after that period, we assessed the changes in fluid volume intake, time spent in wet diapers, size of diaper pads, and urination habits. The result was that fluid volume intake significantly increased (p<0.001) while time spent in wet diapers decreased (p<0.001). The number of residents wearing diapers decreased as did the size of pads during the day (p=0.0017). The proportion of residents using diapers at night was reduced and those using toilets at night increased (p=0.007). This study suggests that such an individualized and comprehensive care strategy can offer a measurable improvement in UI care.

Distribution of a 27-bp deletion in the band 3 gene in South Pacific islanders

AbstractDistribution of a 27-bp deletion in the band 3 gene (B3Δ27) that causes Southeast Asian/Melanesian ovalocytosis has scarcely been studied in remote insular Southeast Asia and New Guinea. Here the presence of the B3Δ27 was surveyed among a total of 756 subjects from the indigenous populations inhabiting New Guinean islands and remote insular Southeast Asia by using a polymerase chain reaction method. In remote insular Southeast Asia where Austronesian-speaking peoples inhabit, the B3Δ27 frequency ranged between 0.04 and 0.15. In New Guinea Island, hinterland or Papuan groups showed the absence of the B3Δ27 or a very low gene frequency (0.01 in the Gidra) of the B3Δ27. However, groups of the coastal regions (Asmat, Sorong, and others) and of the nearby islands (Biak and Manus) where Austronesian infiltration had occurred showed substantial frequencies of the deletion (0.02-0.09). It is likely that the B3Δ27 was introduced into this region about 3,500 years ago with the arrival of Austronesian-speaking peoples. Once being introduced, the B3Δ27 may have been selected because of its resistance against malaria, while founder effect and genetic drift might have occurred in the New Guinean tribes with small population size, which helped to generate a variety of the B3Δ27 frequencies.

Polymorphisms in the ABO blood group gene in three populations in the New Georgia group of the Solomon Islands

AbstractTo examine genetic affinity among Oceanian populations, polymorphisms of exons six and seven of the ABO blood group gene (ABO) were investigated in three populations—Munda town, Paradise village, and Rawaki village—in the New Georgia group of the Solomon Islands. The Munda and Paradise populations consist of Austronesian (AN)-speaking Melanesians; the Rawaki population consists of AN-speaking Micronesians who migrated from the Gilbert Islands to the New Georgia Islands approximately 30 years ago. We recently described the polymorphisms of ABO in three other Oceanian populations—Balopa Islanders (AN-speaking Melanesians), Gidra (non-AN-speaking Melanesians), and Tongans (AN-speaking Polynesians). The results from these six Oceanian populations suggest: (1) the main alleles in Oceanian populations are ABO*A101, ABO*A102, ABO*B101, ABO*O01, and ABO*O02, among which the most predominant is ABO*O01, and (2) there are marked differences in the ABO allele frequency spectrum among Oceanian populations. The different geographical distribution of ABO alleles provides insight into the migration history of AN-speaking populations in Oceania.