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Biomedical subjects

R Ohtsuka

Publications and source records attributed to R Ohtsuka.

At least 37 records · Page 2Linked to original sources
PubMed1999

Seasonal fluctuation in energy balance among farmers in Northeast Thailand: the lack of response of energy intake to the change of energy expenditure.

OBJECTIVE: The study aimed to clarify the seasonal fluctuations in energy balance and their factors among rice-growing farmers in Northeast Thailand whose rice production was enough to their food energy demand. DESIGN: Prospective and repeated measurements in the field. SETTING: A rain-fed rice-farming village. SUBJECTS: Eight pairs of husband and wife. INTERVENTIONS: In each of four periods in a year, anthropometry, energy expenditure survey with heart-rate monitoring and minute-by-minute activity recording, and food consumption survey were conducted for each subject for 4 days. RESULTS: The change of body weight was modest but differed significantly (P < 0.001) between pre-harvest and post-harvest seasons: 1.3 kg (2.3%) for males, 2.5 kg (4.3%) for females. Total energy expenditure (TEE) fluctuated markedly between the 4 seasons (P < 0.001 for males and females), but total energy intake (TEI) fluctuated to lesser extents (P < 0.05 for females only). In relation to energy expenditure, physiological indicators (except respiratory quotient) did not fluctuate throughout the year but behavioral indicators did. The changes in body weight were significantly correlated with the changes in TEE (r = 0.60, P < 0.05 for males; r = 0.83, P < 0.01 for females) but not with the changes in TEI; TEE and TEI were not correlated. CONCLUSIONS: The modest seasonal changes in body weight among rain-fed rice farmers in Northeast Thailand were caused by the lack of response of TEI to the change of TEE.

Adult↗
PubMed1999

Accumulation of soybean glycinin and its assembly with the glutelins in rice

Saline-soluble glycinins and insoluble glutelins are the major storage proteins in soybean (Glycine max) and rice (Oryza sativa), respectively. In spite of their differences in solubility properties, both proteins are members of the 11S globulin gene family based on their similarities in primary sequences and processing of the coded protein. Wild-type and methionine-modified glycinin coding sequences were expressed in transgenic rice plants under the control of the rice glutelin GluB-1 promoter. Glycinins were specifically synthesized in the endosperm tissue and co-localized with glutelins in type II protein bodies. They assembled into 7S and 11S species, similar to what was observed in developing soybean seeds. This pattern was quite different from that displayed by the rice glutelins in untransformed plants, in which processed subunits sedimenting at 2S were apparent. In glycinin-expressing transgenic plants, however, glutelins were observed sedimenting at 7S and 11S with lesser amounts in the 2S region. A portion of the glycinins was also found associated in the insoluble glutelin fraction. Renaturation experiments suggested that the hybrid glycinin-glutelin oligomers were formed through specific interactions. Overall, these results indicate that despite significant differences in the assembly of soybean glycinin and rice glutelin, both proteins can assemble with each other to form soluble hexameric oligomers or insoluble aggregates.

Journal Article↗
PubMed1999

Sleep patterns and sleep disorders among female shift workers in a computer factory of Japan.

Using a repeated questionnaire survey for female workers in a computer factory of Japan, consisting of 45 daytime workers and 84 weekly rotating shift workers (of whom 40 and 44 were respectively engaged in early-shift work and late-shift work during the survey week), the present study aimed to clarify the effects of shift work on their sleep patterns and sleep disorders. The time of retiring, time of rising, duration of sleep, and self-evaluated sleep quality based on four sleep-related problems were investigated for four days (Sunday-Monday, Tuesday-Wednesday, Thursday-Friday, and Saturday-Sunday) in a week. The intergroup comparison revealed that the earlier the rising time and the shorter the duration of sleep, the lower the sleep quality; the lowest sleep quality was observed in the early-shift workers.

Analysis of Variance↗
PubMed1999

Growth and residential conditions of a slum community in Colombo, Sri Lanka.

Based on the authors' fieldwork, this article examined the spatial and demographic growth of a slum community in Colombo, Sri Lanka, in association with the inhabitants' socioeconomic conditions. In this slum community, which is near the industrial and commercial centers and has developed especially since the early 1970s, most dwellers are migrants from other parts of Colombo. The increase of dwellers resulted in a high-density residential condition, represented by an extremely small floor area per person, despite an income level that is not extremely low.

Humans↗
PubMed1998

Impact of rural-urban migration on fertility: a population ecology analysis in the Kombio, Papua New Guinea.

The Anjangmui dialect group of the Kombio in Papua New Guinea has experienced a rapid increase in rural-urban migration since European contact commenced in the 1930s. Population ecology analyses of birth and migration histories for 240 Anjangmui women showed a higher total marital fertility rate in the cohort born in 1940-59 than that born in 1920-39. A decline in the age at menarche for nutritional reasons, and reduction in the birth interval for behavioral reasons, may explain the fertility difference between cohorts. Comparison of age-specific marital fertility rates between migrants in urban areas and non-migrants in rural areas revealed higher rates among migrants in the 15-19 and 20-24 year age groups, but lower rates in the 25-29 year or older age groups; the total marital fertility rate for migrants was lower than that for non-migrants. The differences may be attributable to the different influences of birth control practices on fertility reduction between the migrants in urban areas and non-migrants in rural areas. It is suggested that rural-urban migration in the Anjangmui during the post-contact period has had the effect of reducing fertility in the population as a whole.

Adolescent↗
PubMed1997

Analysis of completed parity using microsimulation modeling.

"This paper aims to construct a demographic microsimulation model, which is easily applicable to gene transmission..., and to examine the distribution of completed parity as a fertility measure at a population level according to the schedule of individual life course....The simulation model was applied to the data of the Gidra-speaking people living in the lowlands of Papua New Guinea."

Birth Rate↗
PubMed1997

Histological characteristics of respiratory system in Brown Norway rat.

It is well known that the Brown Norway (BN) rat strain exhibits airway hyperresponsiveness to exposure to allergens or some chemicals. We investigated the histological characteristics of the trachea and lungs of this strain (10-week-old and retired animals) and compared them with those of age-matched Fischer 344 (F344) rat strain. No histological differences between two strains in tracheal epithelial cells were detected, but differences in the distribution and development of submucosal glands were clarified by the observation of serial sections cut at intervals of 100 microns. Submucosal glands of BN strain were larger in the number and better-developed than those of F344 strain, especially in the middle and lower trachea. Similar results were also obtained in scanning electron microscopic observation of resin casts. There were no significant differences between two strains in the lectin histochemical characteristics of the cytoplasm of glandular epithelial cells. No age-related changes in these morphological characteristics in the two strains were observed. These results suggest that mucin from submucosal glands is quantitatively different but qualitatively similar in the two strains. In addition, microgranuloma mainly composed of histiocytes and eosinophils was observed in the lungs of the BN strain rats.

Animals↗
PubMed1997

Response of respiratory epithelium of BN and F344 rats to formaldehyde inhalation.

BN rats are well-known for their high capacity for IgE production and hyperresponsiveness to exposure to allergens or other chemicals. We examined the histological changes in the nasal cavity, trachea and lungs of BN and F344 rats after the inhalation of aerosol formaldehyde (HCHO), which exerts direct toxic effects on the respiratory system. The incidence of clinical signs such as sneezing and abnormal respiration in HCHO-treated F344 rats was higher than that in HCHO-treated BN rats. The mean body weight of HCHO-treated F344 rats apparently decreased in comparison with control F344 rats, but that of HCHO-treated BN rats was not significantly different from that of control BN rats. Changes such as squamous metaplasia, stratification, degeneration and desquamation were observed by light microscopy in nasal, tracheal and bronchial mucosa in the lungs of the HCHO-treated F344 rats. In the HCHO-treated BN rats, similar but milder lesions were restricted to the nasal mucosa. Scanning electron microscopic observation supported these light microscopic observations. These results suggest that BN rats have lower sensitivity to HCHO inhalation than F344 rats.

Administration, Inhalation↗
PubMed1997

Aging and efficacy of work: a methodological discussion.

Based on a comparison of various human work systems in different cultures, the relationship between efficacy of work and aging is highlighted as a basic component. Age-dependent and age-independent individual variations in labor efficiency in subsistence or nonindustrial societies, which were disclosed in the author's field investigations, are compared with those in industrial societies. Human ergological implications for industrial workers' retirements because of their contracts are also discussed in relation to the behaviorally similar but freely organized work patterns in subsistence societies.

Activities of Daily Living↗
PubMed1996

Stable carbon and nitrogen isotopic composition of diet and hair of Gidra-speaking Papuans.

The carbon and nitrogen stable isotopic composition of the scalp hair and diet of Gidra-speaking people in four villages in Papua New Guinea is presented. The isotopic composition of hair was measured, while that of the diet was estimated from food consumption survey data and the measured isotopic composition and protein and carbohydrate contents of food items. The average isotopic ratios of the hair samples and of the diet varied among the four study villages, which were selected because of their diverse ecological settings. Comparison was made between hair and calculated dietary isotopic compositions. Two of the four diet-hair enrichment values obtained for 13C (+1.8 and 2.2%) were similar to those previously reported (1.4-2.0%), but the other two values (3.7 and 4.8%) were greater than in earlier reports. 15N enrichment was systematically greater (by 1.0%) than reported values (4.3%) except for one village, where a much greater enrichment (6.9%) was found. The factors potentially relevant to these deviations are discussed. Possible errors in estimating the dietary isotopic composition and minor modifications of dietary habits revealed by food consumption surveys could explain most of the discrepancies. However, the great enrichment of 15N found in one of the villages remains unexplained.

Adult↗
PubMed1996

Cold-induced salt intake in mice and catecholamine, renin and thermogenesis mechanisms.

Cold induces increased intake of salt in mice. To examine involvement of renin and catecholamines, male ICR mice were exposed to cold (7-9 degrees C; 6 h/day; 4 days), and half of them were allowed to choose between water and 0.9% NaCl. Plasma renin activity (PRA) and catecholamine concentrations in plasma, adrenal gland, kidney, brown adipose tissue (BAT) and brain were examined in three phases: for 9 h before exposure to cold, during 6 h of cold exposure and for 9 h after the exposure. The amount of salt intake from NaCl solution and from food, PRA and noradrenaline (NE) concentrations in kidney and medulla oblongata were higher during cold and the 9 h after exposure to cold than during the 9 h before the exposure. These results are consistent with the suggestion that cold induced catecholamine metabolism enhanced activity in the renin-angiotensin system, which played an important role in the arousal of salt appetite. During cold exposure, concentrations of NE and dopamine in BAT were higher in mice with access to NaCl solution than those without NaCl to drink. These results suggest that cold-induced salt intake enhanced non-shivering thermogenesis, and are consistent with our previous report that high salt intake helped to maintain colonic temperature under cold exposure.

Adipose Tissue, Brown↗
PubMed1996

Iron nutrition and anaemia in a malaria-endemic environment: haematological investigation of the Gidra-speaking population in lowland Papua New Guinea.

Blood examination was conducted for the four Gidra-speaking village groups in Papua New Guinea, who were characterized by high Fe intake and high malaria prevalence with marked inter-village differences. The northern riverine villagers, whose Fe intake was higher than the other three village groups, did not suffer from Fe-deficiency anaemia in their malaria-endemic environment; nor did the inland villagers, with their second highest Fe intake and their malaria-free environment, suffer from Fe-deficiency anaemia. However, several individuals of the southern riverine village suffered from anaemia in a malaria-endemic environment, although their Fe intake was almost the same as the inland villagers'. A considerable proportion of the coastal villagers were anaemic, reflecting the lowest Fe intake and the highest malaria prevalence. An inter-village comparison of the relationships between haemoglobin levels and transferrin saturation revealed that the southern riverine villagers needed smaller amounts of circulating Fe for erythropoiesis than the northern riverine and inland villagers, reflecting the long-term human-environment conditions such as the density of malaria vectors and the people's dietary habits. Fe supplementation was not judged effective against hypoferraemia and/or anaemia in such a population. As the incidence of malaria had no significant long-lasting effect on Fe stores or circulating Fe concentration, but did have an effect on anaemia, the hypothesis that malaria causes a transfer of Fe from the blood to parenchymal tissues as a defence against infectious diseases was not supported.

Anemia, Iron-Deficiency↗
PubMed1995

HLA-DRB1 frequencies of non-Austronesian-speaking Gidra in south New Guinea and their genetic affinities with Oceanian populations.

DNA typing of HLA-DRB1 genes was conducted for 192 samples from the Gidra who speak one of the non-Austronesian languages and inhabit the southern lowlands of New Guinea. Comparison of the allele frequencies with those of eight other Oceanian populations reveals that the Gidra are genetically closest to the non-Austronesian-speaking Goroka and, next, to the Aboriginal Australian groups, but are remote from the Austronesian-speaking groups in mainland New Guinea and the rest of Melanesia. This finding clearly supports the hypothesis that non-Austronesians and Aboriginal Australians are descendants of the first-stage migrants to Oceania.

Adolescent↗
PubMed1995

Adaptation of the resettled Kenyah Dayak villagers to riverine environment in east Kalimantan: a preliminary report.

The Kenyah Dayak in East Kalimantan (Indonesia), who migrated from their mountainous homeland to a riverine village in the 1940s, have subsisted on slash-and-burn rice cultivation. To cope with rapidly increasing population, the villagers have not changed their farming practice to increase land productivity but instead have exploited fields in remote riverbanks, using motorized canoes.

Agriculture↗
PubMed1995

Hand-arm vibration in tropical rain forestry workers.

Working conditions and health hazards including vibration syndrome related to forestry work using chain-saws were studied in Papua New Guinea and Indonesia. The subjects comprised 291 workers including 97 chain-saw operators. The health examination consisted of peripheral circulatory and sensory tests in the upper extremities. The vibration spectrum measured at the handle of the chain-saw indicated that these acceleration levels would lead to a moderately high risk of hand-arm vibration syndrome (HAVS). The peripheral circulatory function tests revealed dysfunction after more than five years vibration exposure. However, in general, the results of the function tests and subjective complaints showed fewer health problems compared to those of Japanese forestry workers. The reason of such differences of vibration effects seem to be the following: (1) warmer climate (more than 25 degrees C throughout the year), (2) young workers and short work experience. (3) short time vibration exposures on working days in the natural forests, (4) seasonal changes in logging work (5) healthy workers effects. Thus, we found no clear evidence that the workers of our study suffered from HAVS. A principal component analysis was applied. The factor score of the components of the reactive dynamics of peripheral circulation differed significantly after more than five years' exposure. On the other hand, we cannot deny the possibility that subclinical dysfunction of peripheral circulation may be caused by chain-saw operation in the tropics in future. Further investigations on the HAVS among forestry workers in the tropic environment are needed.

Adult↗
PubMed1994

Subsistence ecology and carrying capacity in two Papua New Guinea populations.

This article examines the mechanisms of subsistence adaptation of two Papua New Guinea populations, the Metroxylon sago-depending lowland Gidra and the taro-monoculture Mountain Ok, surviving in low population densities of 0.5 and 1.4 persons per km2. Observation of the groups' land use systems strongly suggests that their population densities have not been far below the carrying capacity, although the territory of each population is markedly heterogeneous. Both groups have maintained their sustainable food production not only for resource management but also for survival at a population level, either expanding their territory or changing the sustainable level in tandem with changes of subsistence system.

Adult↗
PubMed1994

Health status comparison by urinalysis (dipstick test) among four populations in Papua New Guinea.

The health status of four populations depending on traditional subsistence in Papua New Guinea was compared by the dipstick test urinalysis. Conspicuous inter-population difference in the distribution of urinary pH was attributed to the levels of protein intake and the balances of sodium and potassium intake. The percentage of positive findings on protein differed by population along with the percentages of urobilinogen and bilirubin; the higher percentage of protein positives (12-16%) found in less urbanized populations suggests a high risk of hepatic and/or renal disorders in traditional societies. The very low percentage, 0.3 percent, of positive findings on glucose among 1,132 urine samples tested indicated that diabetes mellitus was not yet the major problem. Simultaneously, however, the fact that glucose positives were found only in the most urbanized villages indicates increasing risk of diabetes even in the traditional populations during future urbanization.

Adolescent↗