Yuji Ataka

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.

Influence of Environmental Factors on Performance of Sorptive Building Materials

Recently, sorptive building materials have been used to improve indoor air quality in Japan. By making use of sorptive building materials, the concentration of volatile organic compounds (VOCs) within rooms can be reduced without the need to install any special equipment. In this paper, the effect of sorptive building materials with respect to reducing toluene concentrations in the air of small test chambers has been assessed using sorption flux. We have also examined how environmental parameters influence concentration reduction performance. The effectiveness of activated carbon at reducing toluene concentrations when used as a sorptive building material depend considerably on the air exchange rate of the chamber, the load factor of the sorptive materials and the mass transfer coefficient. In order to evaluate and compare the sorptive performance of various building materials, it is necessary to conduct tests under identical parameter conditions. The experimental results and computational fluid dynamics analysis show that sorptive building materials are a fairly effective agent for reducing indoor VOC concentrations, and that this effect can be expected to be replicated during practical use.

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.

A missense variant, rs373863828-A (p.Arg457Gln), of CREBRF and body mass index in Oceanic populations

It has been suggested that a ‘thrifty’ genotype hypothesis can account for high prevalence of obesity in the island populations of Oceania. A recent genome-wide association study revealed that a missense variant, rs373863828-A (p.Arg457Gln), of the CREBRF gene (encoding CREB3 regulatory factor) was associated with an excessive increase in body mass index (BMI) in Samoans. In the present study, the association of rs373863828-A with an increase in BMI was examined in four Austronesian (AN)-speaking populations in Oceania. We found that rs373863828-A was frequently observed (frequency of 0.15) in Tongans (Polynesians), and was strongly associated with higher BMI (P=6.1 × 10−4). A single copy of the rs373863828-A allele increased BMI by 3.09 kg m−2 after adjustment of age and sex. No significant association was detected in the other three AN-speaking populations (Melanesians and Micronesians) living in Solomon Islands. This was probably due to the low allele frequency (0.02–0.06) of rs373863828-A as well as small sample size. The rs373863828-A allele was not found in both AN-speaking and non-AN-speaking Melanesians living in Papua New Guinea. Our results suggest that rs373863828-A of CREBRF, a promising thrifty variant, arose in recent ancestors of AN-speaking Polynesians.

A functional SNP upstream of the beta-2 adrenergic receptor gene ( ADRB2 ) is associated with obesity in Oceanic populations

OBJECTIVE:Obesity is a growing health concern in the Oceanic populations. To investigate the genetic factors associated with adult obesity in the Oceanic populations, the association of single nucleotide polymorphisms (SNPs) of the beta-2 adrenergic receptor (ADRB2) gene with obesity was examined in 694 adults living in Tonga and Solomon Islands.RESULTS:A screening for variation in 16 Oceanic subjects detected 17 SNPs in the entire region of ADRB2, of which nine SNPs including two non-synonymous ones, rs1042713 (Arg16Gly) and rs1042714 (Gln27Glu), were further genotyped for all subjects. The rs34623097-A allele, at a SNP located upstream of ADRB2, showed the strongest association with risk for obesity in a logistic regression analysis adjusted for age, sex, and population (P=5.6 × 10−4, odds ratio [OR]=2.5, 95% confidence interval [CI]=1.5–4.2). The 27Glu was also significantly associated with obesity in the single-point association analysis (P=0.013, OR=2.0, 95%CI=1.2–3.4); however, this association was no longer significant after adjustment for rs34623097 since these SNPs were in linkage disequilibrium with each other. A copy of the obesity-risk allele, rs34623097-A, led to a 1.6 kg/m2 increase in body mass index (BMI; defined as weight in kilograms divided by height in meters squared) (P=0.0019). A luciferase reporter assay indicated that rs34623097-A reduced the transcriptional activity of the luciferase reporter gene by approximately 10% compared with rs34623097-G. An electrophoretic mobility shift assay demonstrated that rs34623097 modulated the binding affinity with nuclear factors. An evolutionary analysis implies that a G>A mutation at rs34623097 occurred in the Neandertal genome and then the rs34623097-A allele flowed into the ancestors of present-day humans.CONCLUSION:The present results suggest that rs34623097-A, which would lead to lower expression of ADRB2, contributes to the onset of obesity in the Oceanic populations.

Variation in malaria endemicity in relation to microenvironmental conditions in the Admiralty Islands, Papua New Guinea.

For 197 adults and adolescents in four villages of three small islands in the Admiralty Islands, Papua New Guinea, antimalarial antibody titers were examined using the indirect fluorescent antibody test (IFAT) and malaria parasites were detected by the microtiter plate hybridisation (MPH) method using polymerase chain reaction (PCR) technique. The parasite rate (either Plasmodium falciparum or P. vivax, or both) averaged 39.2 %, varying from 31.1 % to 44.8 % among the four villages due to natural and artificial microenvironmental conditions related to breeding sites of mosquitoes (Anopheles farauti). The lack of flat zones owing to geomorphological formation contributed to the lowest parasite rate in the extremely small island. However, human-modified environments such as a wet-land (naturally formed but artificially reformed) and an open well played significant roles in other inter-village differences. The present findings imply significant roles of microenvironment in diversified malaria prevalence and suggest some ways of mitigation of malarial hazards. Asia Pac J Public Health 2001; 13(2): 85-90

Hypertension-susceptibility gene prevalence in the Pacific Islands and associations with hypertension in Melanesia

Human essential hypertension is partly caused by genetic factors. Angiotensinogen (AGT), G-protein β3-subunit (GNB3) and cytochrome P450 3A5 (CYP3A5) are candidate hypertension susceptibility genes and risk alleles at these loci have been thought to arise owing to human adaptation to climatic changes following the migration out-of-Africa. This study aimed to reveal the frequencies of hypertension-susceptibility genotypes in Pacific Island populations and associations of these single-nucleotide polymorphisms (SNPs) to hypertension. Genotyping was conducted for 804 individuals from Melanesian, Micronesian and Polynesian populations at SNPs in the genes encoding AGT (rs699, rs5049 and rs5051), GNB3 (rs5443) and CYP3A5*1/*3 (rs776746). Associations between these SNPs and hypertension were tested for 383 Melanesian Solomon Islanders. We found that the A/A genotype at rs5049 was a risk factor for hypertension (P=0.025) in the Melanesian Solomon Islanders; three SNPs for AGT were in linkage disequilibrium. The ancestral alleles of rs699, rs5051 and rs776746, and the derived allele of rs5443 were as frequent in the populations surveyed here as in other equatorial populations. Although other polymorphisms associated with hypertension and additional populations remain to be studied, these findings suggest that the Pacific Islanders’ susceptibility to hypertension arose because of human migration and adaptation.

Long/Short-Term Performance Test for Evaluating the Reduction of Indoor Formaldehyde Using Sorptive Building Materials

In this paper, a test method for evaluating the ability of sorptive building materials to reduce the concentration of formaldehyde is examined. The authors developed a new method that uses a small chamber to test the suppressive effect of sorptive building material on formaldehyde-emitting materials. Two small chambers were prepared, with the formaldehyde-emitting building material placed in one chamber and a composite building material comprised of sorptive building material attached to the formaldehyde-emitting building material in the other. The formaldehyde emission factors of the two chambers were compared, and the equivalent ventilation rate Qads was calculated. The test method would enable the indoor concentration reducing performance and the suppressive performance of the sorptive building materials to be evaluated at the same time. The suppressive effects of several kinds of sorptive building materials were examined, and accordingly the validity of the test method was verified. The continuous reduction performance of indoor formaldehyde for sorptive building materials using sorption breakthrough capacity method was also evaluated.