Biomedical subjects

M Futatsuka

Publications and source records attributed to M Futatsuka.

At least 19 recordsLinked to original sources

PubMed1998

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.

Adult↗

PubMed1997

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.

Animals↗

PubMed1996

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.

Acrylamide↗

PubMed1996

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.

Adult↗

PubMed1996

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.

Aged↗

PubMed1996

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.

Adult↗

PubMed1996

[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.

Adult↗

PubMed1996

[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.

Exercise↗

PubMed1996

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.

Adult↗

PubMed1995

Magnitudes of neurological disorders in a farming town in Kyushu, Japan: frequency of neurological symptoms and signs.

We examined 1,270 elderly residents aged 60 years and over in a cross-sectional study of a standardized clinical examination to determine the frequency of 'abnormal' neurological findings in 27 randomly selected communities in the town of Mifune, Japan. The survey showed one or more neurological symptoms in 89.1%, and one or more signs in 94.4% of the examined elderly. Most of the symptoms and signs increased with age, especially after 70 years, indicating the importance of neurological afflictions in the community health of the elderly.

Age Factors↗

PubMed1995

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.

1-Propanol↗

PubMed1995

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.

Adult↗

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

[Mercury].

Explore the source record for details and available documents.

Humans↗

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

Vibration exposure and prevention in Japan.

Working conditions of vibration exposure have generally improved, but many difficult problems must be solved such as (1) hygienic improvements in a variety of vibrating tools; (2) improving working conditions, for example, by limiting the time of operation in spite of economic difficulties such as those faced by those who work on a piece rate basis; (3) gathering more complete information about the risk population because of the large number of self-employed in informal employment sectors; and (4) finding work places after rehabilitation for patients, particularly in mountainous rural areas or in small scale industries. Historical observation of vibration and preventive measures in Japanese national forests was presented on the basis of the results of a retrospective cohort study in Kyushu, Japan. Prevalence rate of VWF remarkably changed from 58.4% in the groups that began to operate chain saws in 1960 to only a few cases in the groups who started the operation after 1971. When we compare the relationships between the results of long term cohort study and the consequences of preventive measures of vibration syndrome, the most important factor is the decrease of vibration exposure (improvement in chain saws plus the time restriction system). The comprehensive prevention system used in Japanese national forests consists of the following: (1) Health care system; (2) Work regulation system; (3) System for improving mechanized tools; (4) Warming system to protect against cold conditions; and (5) Education and training system.

Humans↗

PubMed1994

Correlations among examination findings, subjective symptoms and classification of stages in vibration syndrome.

From data collected in 1966, 1973, 1986 and 1989, we analyzed the correlations among examination findings, subjective symptoms, stages in the disorder of vibration syndrome and vibration exposure. As vibration syndrome progressed and vibration exposure accumulated, abnormality of examination findings, the prevalence of vibration induced white finger (VWF), numbness (N) and other subjective symptoms increased. Abnormality of examination findings and prevalence of subjective symptoms in the VWF(+) N(+) group were greatly different from those in the VWF(-) N(-) group. Both findings and symptoms showed closer correlations with VWF(+) than with N(+). Stages in the disorder traced the progression from VWF(-)N(-) to VWF(-)N(+), then to VWF(+)N(+/-), and finally to VWF(+/++)N(+/++). Pathophysiologically, it seems that VWF(+) and N(+) relayed many more cold and pain signals from the hand to the central nervous system. Such signals may activate autonomic nervous activity. In the recovery, subjective symptoms correlated more closely with N(+) than with VWF(+). This is because VWF involves the autonomic nervous system's hyperactivity and hypersensitivity to cold, both of which subside gradually in the recovery; N, however, involves pathological changes in nerve tissue which are irreversible.

Adult↗

PubMed1993

Comparative study of modification and degradation of neurofilament proteins in rats subchronically treated with allyl chloride, acrylamide, or 2,5-hexanedione.

Allyl chloride (ALL), acrylamide (ACR), and 2,5-hexanedione (2,5-HD) are all industrial neurotoxicants and known to produce accumulation of neurofilament (NF) proteins in both the central and peripheral nervous systems. To clarify whether any common mechanisms underlie these neurofilamentous axonopathies, the ability of ALL, ACR, and 2,5-HD to cross-link the NFs and the effects on NF degradation by Ca(2+)-activated neural protease were investigated in spinal cords from rats subchronically treated with these chemicals. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by immunoblot analysis revealed the appearance of high-molecular-weight species of NF triplets immunoreactive to each anti-68K, anti-160K, and anti-200K NF antibody in the 2,5-HD-treated rats, whereas it was not found in those treated with ALL or ACR. A time course study on the degradation of NF proteins conducted by the co-incubation with Ca2+ showed degradation resistance in all three NF subunits from animals treated with 2,5-HD, while no significant alterations in the rate of NF degradation were observed in the ALL- or ACR-treated group. The present results suggest that neurofilament-filled axonopathy induced by ALL or ACR and axonopathy induced by 2,5-HD may not share a common mechanism, though the initial step for the pathogenesis of this chemically induced neurotoxicity is not fully understood at present.

Acrylamide↗