Evaluation of body composition using dual-energy X-ray absorptiometry, skinfold thickness and bioelectrical impedance analysis in Japanese female college students.

We compared three methods for evaluating body composition: dual-energy X-ray absorptiometry (DXA), skinfold thickness (Skinfolds), and bioelectrical impedance analysis (BIA). Subjects were 155 healthy young college-aged Japanese females whose mean+/-SD (range) age, body height, body weight and body mass index (BMI) were 20.1+/-0.3 (19.6-21.1) y, 158.9+/-4.7 (145.4-172.6) cm, 52.0+/-6.8 (39.4-84.6) kg and 20.6+/-2.3 (16.5-32.5), respectively. Their mean skinfold thickness at the triceps and subscapular were 16.9+/-4.7 (8.0-31.0) and 16.0+/-5.7 (7.0-40.0) mm, respectively. Mean body fat mass percentages evaluated by DXA, Skinfolds and BIA were 29.6+/-5.1, 22.8+/- 5.3 and 25.8+/-4.7%, respectively. Body fat mass was 15.4+/-4.4, 12.1+/-4.5 and 13.6+/-4.5 kg, respectively. Simple correlation coefficients between the three methods for body fat mass percentages provided the following coefficients: r=0.741 for DXA vs. Skinfolds, r=0.792 for DXA vs. BIA and r=0.781 for Skinfolds vs. BIA. Simple correlation coefficients for body fat mass were as follows: r=0.898 for DXA vs. Skinfolds, r=0.927 for DXA vs. BIA and r=0.910 for Skinfolds vs. BIA (all p<0.001). There were significant differences in the values among the three methods with the Skinfolds providing the lowest body fat mass and percentage, and DXA the highest (p<0.001). They all appear to be strongly correlated for evaluating body composition: however, different cut-off values for defining obese and lean need to be defined for each method.

Clinical investigation of the lesions responsible for sensory disturbance in Minamata disease.

To clarify the lesions responsible for sensory disturbance in Minamata disease (MD), we clinically investigated the characteristics of sensory disturbance. In all patients with the classical type MD, two-point discrimination was severely disturbed, but the involvement of superficial sensation was relatively mild. On short-latency somatosensory evoked potential study, the component corresponding to N20 was completely absent with normal N9, N11, and N13 components. Although 14 of 38 chronic MD patients demonstrated intact superficial sensation, 10 of these 14 showed mild to moderate disturbance in two-point discrimination. The two-point discrimination in chronic MD patients was significantly high irrespective of the disturbance of superficial sensation. These findings suggest that the sensory disturbance of MD patients may mainly be caused by a lesion in the sensory cortex rather than in the peripheral nerves. However, other foci could be also responsible for the sensory impairment, since 9 of 38 chronic MD patients showed intact two-point discrimination.

Health surveillance in the population living in a methyl mercury-polluted area over a long period.

It is important to follow up on the health status of inhabitants living in the methyl mercury-polluted area surrounding Minamata City, paying particular attention to diseases not only of the central nervous system but also of other organs. We have been carrying out such concentric studies for more than 10 years. We have previously studied the cause-specific standard mortality ratios in Minamata disease patients and reported that the SMRs for liver disease and renal disease were significantly raised in male and female patients, respectively. It was also found that complications arising from diabetes could be due to the large number of old people among the autopsy cases. The next step was to clarify the actual prevalence and incidence of liver disease, renal disease, and diabetes mellitus epidemiologically among the population in this area. The aim of this study was to determine the actual prevalence of these diseases and complaints, and to investigate the contribution of various risk factors to these diseases in this area. The study was a population-based cross-sectional mass screening survey. A case-control study was designed to estimate the role of various risk factors including methyl mercury exposure for these diseases. A mass multiple health examination survey was performed in 1500 subjects aged 40 years and older in Tsunagi Town, neighboring Minamata City, every summer since 1984. Tsunagi Town is located in a methyl mercury-polluted area and there are 36.9 certified Minamata disease patients per 1000 population. Data concerning liver disease, renal disease, and diabetes mellitus were collected on the basis of urine, hematological, physical, and ultrasonographic examinations. Data on risk factors and subjective complaints were collected by interview and other measures. The prevalence of these diseases was not higher in this methyl mercury-polluted area compared with other areas in Japan, contrary to what was expected based on standard mortality ratios and pathological findings. There were no positive correlations between those diseases and methyl mercury exposure. On the other hand, the population in the polluted area had more and a greater variety of complaints than those in the nonpolluted area. It is possible that not only neurological subjective complaints but also nonspecific complaints of the population in the polluted area might be influenced by past methyl mercury exposure. This health surveillance in the population living in a methyl mercury-polluted area must be maintained in the future.

An analysis of subjective complaints in a population living in a methylmercury-polluted area.

The aim of this study is to document subjective complaints, to analyze the structure of a population living in a methylmercury-polluted area, and to investigate the relationship between the subjective complaints and methylmercury pollution. A total of 1304 adults in the polluted area, who were living in the methylmercury-polluted area near Minamata City in Kumamoto Prefecture, Japan, and 446 age-matched adults in a nonpolluted area were interviewed. Comparison of prevalence, factor analysis, and cluster analysis were conducted using data drawn from a questionnaire survey about 64 subjective complaints. The population in the polluted area had more various complaints than that living in the nonpolluted area. The factor analysis proposed four factors: nonspecific, sensory, arthritic, and muscular. Each of the four factor scores was significantly higher in the population in the polluted area. Subjects who had more complaints were classified into three clusters using cluster analysis. It is possible that not only neurological subjective complaints but also nonspecific complaints of the population in the polluted area might be influenced by past methylmercury exposure.

Effect of dietary magnesium level on nephrocalcinosis and growth in rats.

We studied the extent of kidney calcification by varying dietary levels of Mg, based on pathological examinations and calcium (Ca) and magnesium (Mg) balance tests. AIN-76 diets containing varying levels of Mg--0.3 (-M), 1.3 (1/20M), 2.4 (1/10M), 9.2 (1/5M), 19 (control), 38 (2M), 102 (5M), and 187 (10M) mmol/kg diet--were fed to 3-week-old male Fischer-344 rats for 14d. Although the magnitude of abnormality was highest in kidney of rats fed the -M diet, the damage was normalized as the dietary level of Mg increased, with increasing serum Mg concentration and urinary excretion of Mg. We found almost no deposition of Ca in rats fed the 10M diet. The mechanism by which the high dietary Mg induces these effects most likely involves a competition between Mg and Ca for reabsorption in proximal and/or distal tubules, since these diets increased the urinary excretion of Ca. However, these high Mg diets decreased food intake and body weight gain compared with the control diet, although these indices were not decreased in rats fed the 2M diet. The results suggest that a dietary magnesium level approximately twice the normal level effectively reduces kidney calcification while maintaining normal growth in rats.

Whole-body vibration and health effects in the agricultural machinery drivers.

Recently farm mechanization has been widespread and developing rapidly, in particular riding farm machines are increasingly used in paddy fields in Japan. We have no information available on the actual situation regarding whole-body vibration on the seats of these farm machines from the standpoint of labour protection. Measurement and evaluation of whole-body vibration was performed on the seats of popular riding agricultural machineries. Whole-body vibration on the seats of combine harvesters and wheel tractors exceeded exposure limits and the fatigue-decreased proficiency boundary limit of 8 hr and also shortened the reduced comfort boundary limits of ISO 2631 (1985). Some combines, tractors and carieers had only less than one hour exposure duration as compared with the ISO 2631-1 standard (1997). On the other hand a questionnaire was also performed on the subject of agricultural machine operators. Any specific injury or other effects, i.e. low back injuries were not found among the group of operators as compared with those in non-operator farmers. It seems to be difficult to find out the health effects of whole-body vibration itself, because there may be a lot of causes, i.e. working posture, operating heavy materials, in farm working conditions.

Different administration schedules of the same dose of 2,5-hexanedione influence the development of neuropathy and the toxicokinetics.

The same total dose (1.2 g/kg/week) of 2,5-hexanedione (2,5-HD) was administered subcutaneously at 100 mg/kg/12 hr, 200 mg/kg/24 hr, and 400 mg/kg/48 hr to three groups of Donryu rats. The peripheral neuropathy induced by 2,5-HD was confirmed by clinical observation every day, and neurophysiological measurements every 4 weeks. During the 15th week of this experiment, 2,5-HD concentrations in plasma 0.5 to 24 hours after injection were determined. It was found that the greater the dose of 2,5-HD per treatment injected, the earlier peripheral neuropathy developed. Toxicokinetic analysis showed that both the values of the area under the plasma concentration versus time curve and the half life of 2,5-HD were increased, but the excretion parameters (Ke) were decreased, in animals treated with 200 mg/kg/24 hr and 400 mg/kg/48 hr 2,5-HD.

Risk estimation for hypertension based on follow-up health examination data in a small village in Kumamoto prefecture, Japan.

The estimation of risk for incidence of hypertension was carried out by follow-up study in a small village in Kumamoto Prefecture, Japan (N=750, 48.2±15.2months). The most significant risk in both sexes was blood pressure at entry. As for other risks, age, total cholesterol, and BMI in females were significant risks for systolic and diastolic blood pressure changes to greater than the borderline level. These factors in males were not significant. From the results of analysis using Cox's proportional hazards model, drinking in males was shown to be a significant risk for diastolic change, and in females for systolic change. It was concluded that excessive drinking in both sexes and obesity in females led to important health problems associated with hypertension among the subjects of the study.

An epidemiological study on diabetes mellitus in the population living in a methyl mercury polluted area.

The aim of this study was to determine the actual prevalence of diabetes mellitus and to investigate the contribution of various risk factors to the diabetes mellitus among the population in a methyl mercury polluted area. The study was a population based cross sectional mass screening survey. A case-control study was designed to estimate the role of various risk factors including methyl mercury exposure for diabetes mellitus. The study was confined to a small rural town 10 km north of Minamata City; 1,087 persons older than 40 years were examined. Measurement of glucose metabolism was made on the basis of urine and haematological examinations. Data on risk factors were collected by questionnaire, and by measurement of body height and weight (obesity). The prevalence rate of the diabetes mellitus was 8.4% in males and 5.3% in females. The odds ratio of family history was significantly higher, 4.63. The odds ratio of residential history in a methyl mercury high polluted area was 0.58. The prevalence of the diabetes mellitus in this methyl mercury polluted area was not increased, contrary to what was expected based on the pathological findings.

[A questionnaire study on health administration in small enterprises in a rural region].

A questionnaire study on the health administration of industrial workers was performed on 230 enterprises in city A in a rural region. Responding subjects numbered 140 and the response rate was 60.9%. Subjects by scale were: 16% with more than 50 workers, 48% with from 10 to 49 workers and 36% with less than 10 workers, and the proportions by industry were: 32% manufacturing, 22% wholesale-retail trade and 14% construction. The subject proportions classified according to the health insurance scheme were: 59% government-managed health insurance, 15% national health insurance and 11% society-managed health insurance. The rate of periodic health examination was 100% in enterprises with more than 50 workers, 67.2% in those with from 10 to 49 workers and 51.0% in those with less than 10 workers. The main reasons why then did not receive health examinations were: 40% had no time available to conduct examinations, 21% believed such examinations were not necessary, and 19% did not know of such an examination system. They encountered some difficulties in promoting health; for example, the advanced age of workers, and no time or money to spare for health administration. They desired provision of facilities close at hand for health examination, health consultation and health information. The results of this study show the difficulty of promoting health administration in small scale enterprises and also that it is difficult to obtain accurate information on actUal conditions including health administration in small enterprises.

Cancer mortality in Minamata disease patients exposed to methylmercury through fish diet.

We report here a historical cohort study on cancer mortality among Minamata disease (MD) patients (n = 1,351) in Kagoshima and Kumamoto Prefectures of Japan. Taking into account their living area, sex, age and fish eating habits, the residents (n = 5,667; 40 years of age or over at 1966) living in coastal areas of Kagoshima, who consumed fish daily, were selected as a reference group from the six-prefecture cohort study conducted by Hirayama et al. The observation periods of the MD patients and of the reference group were from 1973 to 1984 and from 1970 to 1981, respectively. Survival analysis using the Poisson regression model was applied for comparison of mortality between the MD patients and the reference group. No excess of relative risk (RR) adjusted for attained age, sex and follow-up period was observed for mortality from all causes, all cancers, and non-cancers combined. Analysis of site-specific cancers showed a statistically significant decrease in mortality from stomach cancer among MD patients (RR, 0.49; 95% confidence interval, 0.26-0.94). In addition, a statistically significant eight-fold excess risk, based on 5 observed deaths, was noted for mortality from leukemia (RR, 8.35; 95 % confidence interval 1.61-43.3). It is, however, unlikely for these observed risks to be derived from methylmercury exposure only. Further studies are needed to understand the mechanisms involved in the observed risks among MD patients.

The effects of 2,5-hexanedione and acrylamide on myosin heavy chain isoforms of slow and fast skeletal muscles of the rat.

We examined the effects of 2,5-hexanedione (2,5-HD) and acrylamide (ACR) on the muscle fiber types and myosin heavy chain (MHC) isoform composition of the slow-twitch soleus and fast-twitch plantaris muscles of rats. We employed two differently designed experiments with respect to the dosage levels and treatment periods for developing clinical neuropathies. When male Wistar rats were subcutaneously injected with 4.5 mmol of 2,5-HD/kg or 0.4 mmol of ACR/kg, 5 days a week, they developed paralysis of the hindlimbs in 4 weeks (high-dosage experiment). When they were subcutaneously injected with 3.5 mmol of 2,5-HD/kg or 0.35 mmol of ACR/kg, 5 days a week, paralysis of the hindlimbs did not develop until 6 weeks (low-dosage experiment). We examined mainly the rats treated with the neurotoxicants for 4 and 8 weeks in the high-and low-dosage experiments, respectively. Significant decreases in the maximum motor conduction velocity of the sciatic nerves were observed in the hindlimbs of the rats in both experiments. The weights of the soleus and plantaris muscles were significantly reduced in the 2,5-HD-treated rats in both experiments, while in the ACR-treated rats, the weights of both muscles decreased only in the low-dosage experiment. We could not detect any changes in the fiber type composition of the muscles by any of the treatments. However, biochemical analysis revealed decreases in the values (percentage) of the relative amounts of fast-type MHC IIa and IIb isoforms to total MHC isoforms in the 2,5-HD-treated rats, but not in the ACR-treated rats in the high-dosage experiment. In contrast, significant differences in the relative amounts of MHC isoforms were not observed after administration of the low dosage of 2,5-HD. These results suggest that 2,5-HD preferentially disorders the muscle fibers which contain the MHC II isoform. These effects may occur only after the relatively acute intoxication of 2,5-HD at a high dosage.

Vibration exposure dose dependency of clinical stage, examination results and symptoms in vibration syndrome.

The vibration exposure dose dependency of clinical stage, examination results and symptoms are valuable for evaluation of exposure effect in vibration syndrome. The 1973 national survey of 461 chain saw operators in private forests was reexamined with respect to vibration exposure dose (VD) and clinical stage (Stockholm Workshop scales: CIRP-0 to 3 and SN-0 to 3 stages). VD was calculated by the formula "ahw(eq.4h) x D (days) x Y (years)". Vibration exposure dose index (VDI) was calculated according to the VD level. Subjects were divided into five VDI, four CIRP stage and four SN stage groups, respectively. Ratio of four CIRP and SN in VDI, examination results and prevalences of symptoms were compared between VDI-1 and the other VDI groups. Vibration dose dependency was observed in Stockholm Workshop scales (CIRP and SN stage) and examination results (prevalence of CIRP, vibrotactile perception threshold, prevalence of numbness in hands, and fingertip pinch strength). Higher VDI (VDI-5) was associated with higher prevalence of hypersensitivity to cold, muscle weakness and deterioration of finger function. Which formula is more useful to evaluate cumulative vibration effects is still controversial.

[Epidemiologic survey of pleural plaques among inhabitants of Matsubase exposed to asbestos].

A high prevalence of pleural plaques (41.5%, 148/357) was found during a mass screening for lung cancer in Matsubase town in 1988. The inhabitants of this town were carefully studied each year from 1988 to 1993. The vast majority (81.2%) of inhabitants over the age of 20 years underwent chest roentgenography at least once during this period. Pleural plaques were detected by CT in 938 subjects, which is 17.3% of those studied and 4.1% of the total population. A total of 89 had an occupational history of asbestos exposure, 64 (71.9%) of whom had pleural plaques. However, these subjects with occupational exposure accounted for only 6.8% of the 938 subjects, and therefore most of the pleural plaques seemed to have been caused by general environmental exposure. The incidence of plaques was greater in older subjects: among those in the seventh decade of life it was more than eight times higher than among those in the fourth decade of life. Anthophyllite was detected in the main asbestos mill. The concentrations of asbestos fibers in the air and water near the old asbestos mills and factories were not high. The death rates and the adjusted mortality rates due to lung cancer in Matsubase were lower than in surrounding towns and lower than in Kumamoto prefecture as a whole. These results indicate that there is now no environmental contamination by asbestos fibers in Matsubase town. No cases of malignant mesothelioma have been confirmed in this town during the past 17 years.

An experimental study on changes in finger blood pressure during chain-saw operation.

In this study finger blood pressure was observed by using a new method to determine if vasoconstriction activated by sympathetic nervous system takes part in changes in peripheral circulation with exposure to vibration, noise and tool weight. Finger blood pressure was measured every one minute by ambulatory monitoring system. The time profile of a single experiment consisted of 5 minutes pre-exposure period followed by one exposure period lasting 2 minutes and a post exposure period of 5 minutes. Measurement was carried out as a factorial experiment of combination of vibration (17.8 m/s2 in X-axis, 20.0 m/s2 in Y-axis and 50 m/s2 in Z-axis), noise (105 dBA) and tool weight (7.9 kg). Finger blood pressure increased significantly under the following conditions: vibration + noise + tool weight > vibration + noise .=. vibration .=. tool weight > noise .=. control. During exposure period the combination with vibration, noise and finger grip exercise induced 29.7 mmHg of increases on average in finger blood pressure. On the other hand, finger blood pressure was increased 9.5 mmHg by vibration alone. These results agreed with our previous studies which observed the decreases of finger skin temperature and finger blood flow during the same conditions. The present study suggests that possible activation of the sympathetic nervous system may be involved in the physiological mechanisms of the changes in blood flow during chain-saw operation.

Modifications of neurofilament proteins by possible metabolites of allyl chloride in vitro.

Chronic exposure to allyl chloride (ALL) is known to produce a central-peripheral distal axonopathy. In relation to the mechanism(s), the present study was conducted to examine the abilities of ALL and its putative metabolites, i.e., epichlorohydrin, glycerol alpha-monochlorohydrin, allyl alcohol and acrolein to cross-link proteins in vitro. Neurofilament-riched cytoskeletal proteins (1mg/ml) and ovalbumin (10mg/ml) were incubated with 160 mM tested chemicals except for acrolein at 0.5 mM and 1 mM. Time-dependent studies by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) revealed that not only ALL, but also acrolein and epichlorohydrin exerted chemical modifications on axonal cytoskeletal proteins; while only acrolein-treated ovalbumin could manifest evidence of polymerization of the protein. Immunoblotting of PAGE-separated proteins confirmed that the high molecular weight proteins on the top of SDS-PAGEs were NF antigen-contained covalent cross-linked materials.

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.

Vibration dose, disturbance stage, and examination results and subjective symptoms in vibration syndrome.

The 1973 national survey of 461 chainsaw operators in private forests was reexamined with respect to vibration exposure dose and the Stockholm Workshop Scale (CIRP and SN stages). Vibration dose (VD) was calculated by the formula "ahw(eq.4h) x D (days) x Y (years)". Vibration dose index (VDI) was calculated according to the level of VD. Subjects were divided into five VDI, for CIRP stage, and four SN stage groups. Examination results and prevalence of subjective symptoms were compared between VDI-1 and other VDI groups, CIRP-0 and other CIRP groups, and SN-0 and other SN groups. VD had higher values in CIRP-2 and 3, and SN-2 and 3 than CIRP-0 and SN-0, respectively. The most severe CIRP-3 and SN-3 appeared at higher rate in VDI-4 and 5 groups than in VDI-1 group. VDI had a correlation with mean value of prevalence of CIRP, vibrotactile perception, mean SN stage and fingertip pinch strength. A correlation was observed between skin temperature and CIRP stage, and between vibrotactile perception and SN stage. Decrease of muscle strength and difficulty in fine finger movement were associated with severe sensorineural disturbance.