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Biomedical subjects

R Ohtsuka

Publications and source records attributed to R Ohtsuka.

At least 55 records · Page 3Linked to original sources
PubMed1994

Urinary mercury monitoring of university staff and students occasionally exposed to mercury vapor.

To monitor the exposure to mercury (Hg) vapor among university staff members and students who occasionally handle elemental Hg in laboratory experiments, urine samples were collected at health examinations conducted by the Health Service Center, University of Tokyo, for six years. Geometric mean of urinary Hg concentrations of 343 samples collected from 234 subjects was 1.61 micrograms Hg/g creatinine (Cr), with the range of 0.30 to 9.31 micrograms Hg/g Cr. Elevated urinary Hg levels, i.e. 3 micrograms Hg/g Cr or higher, were found only among the subjects who worked in several laboratories. This urinary Hg level is judged to correspond to 1-2 micrograms/m3 of air Hg concentration in working areas. The contribution of dental amalgam fillings to urinary Hg excretion, though it exists, was concluded to be small from the result of multiple regression analysis.

Dental Amalgam↗
PubMed1994

Differential malaria prevalence among villages of the Gidra in lowland Papua New Guinea.

Antibody titres against Plasmodium falciparum and P. vivax were examined using the indirect fluorescent antibody test (IFAT) for 183 Gidra-speaking adults and adolescents in four ecologically different villages of lowland Papua New Guinea. The findings highlight that 1) in Gidraland P. falciparum was more prevalent than P. vivax, 2) the proportion of antibody titres of 1:64 or higher markedly differed among the villages, ranging from 35.3% to 100% for males and from 31.6% to 100% for females, and 3) in the two villages with high prevalences, these were higher among males than females. The inter-village and sex differences can be largely explained by microenvironmental conditions and behavioural patterns of the population. The population-based analyses of this study intend to contribute to a better understanding of the prevalence of malaria in human-environment settings and thus to the planning of malaria prevention.

Adolescent↗
PubMed1993

HTLV-I, HIV-I, and hepatitis B and C viruses in Western Province, Papua New Guinea: a serological survey.

Seven hundred and twenty-three serum samples from individuals in 13 Gidra-speaking villages in Western Province, Papua New Guinea were tested for evidence of infection with human T-lymphotropic virus type I (HTLV-I), human immunodeficiency virus type I (HIV-I), hepatitis B virus (HBV) and hepatitis C virus (HCV). No samples were positive for antibodies to HIV-I. Antibodies to HTLV-I were found in 13 samples (1.8%), HBV surface antigens (HBsAg) were found in 86 samples (11.9%), and antibodies to HCV were found in 30 samples (4.1%). Six (46.2%) of 13 HTLV-I positive samples were positive for HCV or HBsAg. The seropositive rate varied in different villages and the incidence of HTLV-I and HCV was higher in coastal and riverine areas than inland.

Female↗
PubMed1993

Changing population structure and commuting situation in Tokyo Megalopolis: a municipality-based analysis.

Census data was analyzed for 20 municipalities along the Tohoku Line in Tokyo Megalopolis to elucidate the changes in the population structure and the commuting situation in the last two decades. The major findings were: (1) the changing pattern of population structure markedly varied among the municipalities, and (2) the long-distance commuting workers have increased particularly among those 50 km or more from central Tokyo.

Adolescent↗
PubMed1992

Mercury concentration correlates with the nitrogen stable isotope ratio in the animal food of Papuans.

The relationships among element concentrations (Na, Mg, Al, P, K, Ca, Cr, Fe, Mn, Cu, Zn, Sr, total Hg, organic Hg, inorganic Hg, Pb) and stable carbon and nitrogen isotope ratios (13C/12C and 15N/14N) in animals consumed by the people called Gidra, who inhabit the lowland of Papua New Guinea, were examined. Animals analyzed included mammal, bird, fish, shellfish, reptile, crustacean, and insect. Highly significantly positive correlations were observed between total Hg concentrations and 15N/14N (r = 0.796), between organic Hg concentrations and 15N/14N (r = 0.781), and between inorganic Hg concentrations and 15N/14N (r = 0.739). This was interpreted to indicate that Hg was an element which accumulates in animals along the food chain. Based on the regression function of Hg on delta 15N, the bioconcentration factor for total, organic, and inorganic Hg was estimated to be 5.

Diet↗
PubMed1991

[Neurosurgical management of dialyzed patients].

Cerebrovascular disease is a lethal complication for patients with renal failure because of the hemostatic disturbance and equivocality about management of the central nervous system. Appropriate management of the renal failure in neurosurgical patients was considered on the basis of experience. Hemodialysis (HD), which is the most common dialysis method, has a serious disadvantage: the elevation of intracranial pressure during dialysis due to the "disequilibrium syndrome." It is important to stabilize the serum osmolarity during dialysis in order to prevent the disequilibrium syndrome. From this point of view, continuous ambulatory peritoneal dialysis (CAPD) has great advantages; serum osmolarity is not rapidly changed and no anticoagulants are required during dialysis. CAPD is recommended as the first method of choice in neurosurgical management of renal failure patients. However, if a patient has to be maintained with HD because of a history of laparotomy or peritonitis, it is essential to keep the serum osmolarity as stable as possible using the extracorporeal ultrafiltration method, hypernatremic HD, bicarbonate HD, and intravenous administration of glycerol.

Adult↗
PubMed1991

A preliminary study on the function tests of the vibration syndrome in tropical rain forest workers.

Working situations and health hazards directly related to the work of the tropical rain forest workers were studied in Papua New Guinea. The results of the function tests of the vibration syndrome were reported in the preliminary step of this study. Among 61 workers including 16 chain saw operators no clear evidence was found that was related to the health effects of hand-arm vibration, but a possibility existed of an occurrence of subclinical dysfunction of peripheral circulation and peripheral neuropathies. The principal component analysis suggests that the reactiveness of peripheral circulation significantly reflects the duration of the chain saw operation.

Adult↗
PubMed1989

Hunting activity and aging among the Gidra Papuans: a biobehavioral analysis.

From the individual-based records of hunting practice for 1,633 hr in total and from the hunters' visual acuity and grip strength observed among the Gidra Papuans in lowland Papua New Guinea, this paper aims to analyze the relationship between the hunting activity and aging. The sensori-motor functions determine the range of age in which the individuals act as active or productive hunters: determined to be from the late teen-age years to about 45 years among the present subjects. In this age range, hunting efficiency increases with age. In terms of weight of animals killed per hunting time, the efficiency of the elder married (aged about 35 to 45 years) was almost four times higher than that of the unmarried (16-17 to late 20s). This aging effect is judged to depend on behavioral abilities that increase in accordance with experience and cumulative knowledge. Simultaneously, the comparison of individual hunters' records in 1971-72 and in 1981 reveals that hunting efficiency is associated with the individualities of the hunters.

Adolescent↗
PubMed1988

Combined biochemical and immunochemical comparison of peptidylarginine deiminases present in various tissues.

We have performed a combined biochemical and immunochemical study on the identity of peptidylarginine deiminases (EC 3.5.3.15) present in various mammalian tissues. First, we purified peptidylarginine deiminase from rat skeletal muscle. It gave a single band of molecular weight 83,000 in sodium dodecyl sulfate polyacrylamide gel electrophoresis. Next we immunized rabbits with the purified enzyme. The resulting antibodies reacted specifically with the antigen in Western blot assay. Most of the enzyme activities present in rat skeletal muscle, brain, spinal cord, submaxillary gland and spleen could be characterized as the same muscle-type enzyme by immunoprecipitation and Western blot assay. The antibodies did not react with enzyme samples obtained from rat hair follicles and bovine epidermis. The lack of immunoreactivity of the epidermal enzyme could not be accounted for by the species difference, since the antibodies reacted with a 83 kDa polypeptide of bovine brain, which was thought to represent a bovine counterpart of the muscle-type enzyme. The epidermal enzyme could be distinguished from the other enzyme samples by its high activity towards benzoylarginine. These data suggest the existence of at least three types of peptidylarginine deiminase in mammalian tissues, i.e., a muscle type, a hair follicle type, and an epidermal type.

Animals↗
PubMed1987

[Studies on cytosol thyroid hormone binding proteins in the rat liver: Part II. Alterations of thyroid hormone binding proteins in various thyroid function states].

Alterations of binding characteristics of cytosolic thyroid hormone binding proteins (CTHBPs) were examined in livers of rats with different thyroid function. Seven days after thyroidectomy, rats were divided into three groups. Group I received no treatment. Group II was treated with 230 ng triiodothyronine (T3)/100 g body weight per day for three days, and Group III with 40 micrograms T3/100 g body weight per day for three days. On the fourth day, each rat was given 0.7 microCi of 125I-T3/100 g body weight intraperitoneally and exsanguinated two hours later. During three days' treatment, body weight in Group II increased significantly compared with that in Group I (P less than 0.05), and body weight in Group III actually decreased. The ratio of liver weight to body weight in Group II was significantly higher than that in Group I or Group III (P less than 0.01). Percent distributions of 125I-T3 in cytosol fraction per liver or concentrations of cytosolic protein did not differ significantly among these three groups. Serum T3 concentrations (mean +/- SD ng/ml: Group I; not detectable, Group II; 0.50 +/- 0.27, Group III; 7.10 +/- 2.31), cytosolic T3 concentrations (mean +/- SD ng/ml: Group I; not detectable, Group II; 0.59 +/- 0.26, Group III; 10.38 +/- 3.08) and mitochondrial alpha-glycerophosphate dehydrogenase activities (mean +/- SD delta OD500 millimicrons/min/mg: Group I; 28.0 +/- 1.5, Group II; 46.7 +/- 7.3, Group III; 267.7 +/- 9.1) suggested that Group I was in hypothyroid state, Group II in euthyroid state and Group III in thyrotoxic state. Binding characteristics of cytosolic T3 binding protein (CT3BP) were different among the three groups.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

[Studies on cytosol thyroid hormone binding proteins in the rat liver: Part III. Partial purification and binding characteristics of thyroxine-binding protein in hypothyroid rat liver cytosol and serum].

Cytosolic thyroxine-binding protein (CT4BP) was partially purified from rat liver cytosol obtained 10 days after thyroidectomy using Sephadex G-200 gel filtration, and its binding characteristics were analyzed in displacement experiments using a charcoal binding method to separate bound and free hormones. Serum T4-binding proteins were also partially purified, and their binding characteristics were similarly determined. Sephadex G-200 gel filtration of liver cytosol from thyroidectomized rats revealed that CT4BP had an apparent molecular weight of 100 X 10(3) daltons. CT4BP had a very high affinity constant (Ka) of 2.2 +/- 10(10) M-1 and a small maximum binding capacity (MBC) of 5.1 X 10(-9) g/mg. protein for T4. Relative affinities of T4 analogues for CT4BP (if the affinity of L-T4 was assigned a value of 100, then D-T4 would have a value of 25.3; L-T3, 16.6; D-T3, 2.3; reverse T3, 1.4 and both Tetrac and Triac less than 1) showed that CT4BP had a rigid specificity for alanine-side chain of T4-molecule. This CT4BP was not demonstrated when cytosol from normal rat liver was used. Sephadex G-200 gel filtration of rat serum obtained 10 days after thyroidectomy revealed two T4-binding proteins. The faster peak (Peak I; MW about 100 X 10(3) daltons) was eluted before the albumin peak, and the slower peak (Peak II; MW about 56 X 10(3) daltons) appeared after the albumin peak. Peak I was barely detectable when normal rat serum was used. Peak I had a higher Ka of 2.0 X 10(10) M-1 and a smaller MBC of 3.9 X 10(-9) g/mg. protein than Peak II (Ka; 8.9 X 10(8) M-1, MBC; 3.7 +/- 10(-7) g/mg. protein). Relative affinities of T4 analogues for Peak I (L-T4 100, D-T4, 34.9, L-T3 11.1, D-T3 1.8, reverse T3 6.8, Tetrac 0.25 and Triac 0.1) showed that Peak I had a rigid specificity to alanine-side chain of T4 molecule, but Peak II had little specificity to this side chain (L-T4 100, D-T4 9.2, L-T3 2.1, D-T3 1.0, reverse T3 14.3, Tetrac 69 and Triac 26.3). Thus, Peak I had a similar binding characteristics to those of human thyroxine-binding globulin (TBG), and Peak II was comparable to human thyroxine-binding prealbumin (TBPA). The results that both molecular weight and binding characteristics were similar between CT4BP and Peak I suggest that both proteins are identical, being comparable to human TBG. This must be clarified in future.

Animals↗
PubMed1986

Low rate of population increase of the Gidra Papuans in the past: a genealogical-demographic analysis.

The population increase rate of the Gidra in lowland Papua in the past was estimated using the rate of intergenerational replacement of females based on genealogical records involving 889 women, alive or deceased, who completed reproduction. During the period from a century ago to the time of manifest influence of civilization several decades ago, the Gidra had a constant annual increase rate of about 0.2%. The discussion includes a historical assessment of this rate with reference to the local conditions and an ecological explanation for its microenvironmental variation and suggests a reassessment of the methodology for studying fertility and population growth in anthropological and prehistoric populations.

Female↗