Skin histidase activity and urine formiminoglutamic acid (FIGLU) in patients with histidinemia found by screening newborn infants.

Skin histidase activities and urine formiminoglutamic acid (FIGLU) levels were measured in 20 patients with histidinemia, identified by Guthrie's screening method, and their family members as well as control subjects. There was a significant positive correlation between skin histidase activities and the amounts of urine FIGLU. Although the difference of skin histidase activity and the amount of urinary FIGLU was significant between any two of the three groups (i.e. controls, parents and patients; p less than 0.005), these levels ranged widely and a considerable number of the cases overlapped among groups. When a discriminant function was computed to obtain the minimum probability of misclassification between the groups using the above two parameters, a better segregation was observed. However, even though the number of misclassifications decreased, the overlapping cases were still present, especially between the parent and patient groups. It is concluded that either skin histidase activity, urine FIGLU, or both, can be used as genetic markers of the disease to a large but still limited extent.

Effect of low level acoustic stimulation on temporary threshold shift in young humans.

To assess the effect of a low level acoustic stimulation on the susceptibility to noise, young human subjects were exposed to music at 70 dBA for 6 h per day during 9 days (training period). Noise sensitivity was assessed by measuring temporary threshold shift (TTS) induced by 105 dBSPL, 1/3 octave band noise at 2 kHz for 10 min. On the fifth day of the training period, a significant decrease of TTS was observed in the frequency range 3-3.5 kHz, in comparison with the baseline TTS obtained before being trained. As the training continued, the frequency range which showed a significant reduction of TTS expanded to 2-5 kHz.

Noise-induced hearing loss in relation to vibration-induced white finger in chain-saw workers.

From the viewpoint of the etiologies of noise-induced permanent threshold shift (NIPTS) and vibration-induced white finger (VWF), the association between VWF and hearing loss was examined among 499 chain-saw workers who underwent a compulsory health examination for vibration syndrome. They were classified by age, duration of noise and vibration exposure, and the severity of VWF. The severity of VWF was evaluated according to the following criteria: no prior history; VWF history, but symptoms had disappeared; VWF present but appearing rarely; frequent appearance of VWF (more than 20 times per winter season). In three age groups (ie, 40-49, 50-59, 60-69 years) with 5-9 years of exposure, the chainsaw workers with VWF had a significantly greater hearing loss at higher frequencies than those without VWF. However, in the 10- to 14-year exposure groups, a significant difference was not found between the VWF and non-VWF groups, except that the 50- to 59-year age groups showed a significant difference in mean age. It was suggested that interindividual differences in susceptibility to noise and vibration may be the reason for the synergistic effects of noise and vibration.

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.

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.

Hand-arm vibration, noise, temperature and static load--an experimental study of peripheral circulation while operating chain-saws.

From the viewpoint of elucidating the etiological mechanism of vibration-induced white finger (VWF), a model experiment was designed using a chain-saw under laboratory conditions. Finger skin temperature and finger blood flow were measured simultaneously as indicators of peripheral circulatory movement, using a thermister and an apparatus for measuring tissue blood flow based on the thermal diffusion method. In the first project (Experiment A), five healthy subjects operated a chain-saw at a high working speed with-out actually cutting anything. In the second project (Experiment B), seven healthy subjects were exposed to three different kinds of experiments with combinations of hand-arm vibration, noise and tool weight at about 15 degrees C room temperature. In the third project (Experiment C), the effects of tool weight and grip force were examined. In the fourth project (Experiment D), patients suffering from vibration disease were exposed to hand-arm vibration and the noise of a chain-saw for 2 minutes. In experiment A, the mean value of the normalized finger skin temperature decreased gradually with cyclic changes corresponding to each exposure and break period. Changes in finger blood flow had almost the same pattern as the changes of skin temperature, but the recovery of blood flow during a 30 sec break period was notable and a slight elevation of the base line was observed. In experiment B, the mean value for the normalized finger skin temperature decreased much more when the subjects operated a chain-saw at a high working speed than when they operated the chain-saw with the noise isolated by double hearing protection. On the other hand, the results obtained in experiment C indicated that the effect of tool weight should be considered as an important factor for investigating the acute changes in peripheral circulation. In experiment D, some patients showed an unusual pattern in the change of blood flow during a post exposure period which was not seen in healthy subjects.

[An analysis on a relationship between perinatal mortality and live births of low birthweight, in Kumamoto Prefecture, 1968-1994].

The aims of this investigation were to describe the relationship between perinatal mortality rates and the proportions of live births among low birth weight (LBW) infants from 1968 to 1994, and to determine risk factors in infants of low birth weight. Using vital statistics from 1968 to 1994 of the Japanese government and the Kumamoto Prefecture and Maternal and Child Health Statistics of Japan from 1968 to 1995, perinatal deaths and live births of infants of low birth weight were studied according to national statistics criteria. In Japanese and Kumamoto Prefecture, there was an association between perinatal deaths and live births of LBW. The significant decline of perinatal mortality rates from 1968 to 1976, of which the fetal death ratio at 28 weeks and over mostly declined, was closely related to the decline of live births of LBW. In this period, the improvement of socioeconomic conditions and the comprehensive health care provided by the government contributed in improving perinatal mortality rates. From 1977 to 1988, the annual variation of Kumamoto was different from that of all Japan. Both perinatal mortality rates continued to decline due to a general decrease in early neonatal mortality rates. The number of Live births of LBW infants in Kumamoto prefecture increased in 1977 and once again started to decline in 1982. In 1977, the insufficient maternal-child health care and the increase of female workers contributed to increasing rates of live births of LBW. Advances in neonatal medicine contributed to the increase in survival rates of infants of LBW. Although, after 1982, the improvement of maternal-child health care and the perinatal care system contributed to the declining rates of live births of LBW. On the other hand, those rates in all Japan continued to gradually increase from 1977 to 1988. After 1989, perinatal mortality rates continued to decline, and live births of LBW continued to increase in both Kumamoto prefecture and all Japan. These results were contrary to the above results from 1968 to 1976. It was considered that medical advances in the care of pregnant women and neonates increased survival rates of the LBW. In future, the perinatal mortality rates will appear to approach a minimum constant, that is, a minimum of fetal death rates. It is important to reduce the number of LBW infants, particularly birthweight of 2000 g-2499 g, with maternal-child health care.

[Work history, health conditions and hearing loss of Ishigaki fishermen].

Based on our previous health survey among Ishigaki fishermen in 1979, this study aimed at clarifying the relations of their work histories to physical characteristics, physiological functions, blood conditions and hearing levels. Medical examination was conducted in 1987 on 118 fishermen inclusive of 33 followed-up fishermen, and in 1989 noise-level and noise-induced temporary threshold shift of hearing was measured for different fishing methods. The results were as follows; 1) Fishing history was not specifically associated with any physical characteristics. 2) High HDL cholesterol, which was observed among divers using diving apparatus, was considered to be a survival effect for divers, since HDL cholesterol is amplified by intensive muscle work. 3) Abnormalities of ECG except for a high R wave were notably observed among the divers, who once changed from unassisted diving to diving with apparatus and then to fishing lines. The main reason for switching jobs was claimed to be caisson disease, and it was suggested that diving with apparatus was related to a high risk of health hazards in the central nervous system and/or respiro-circulatory system. 4) Acoustic acuity greatly declined with aging, and which was commonly observed in groups with different work histories. By way of explanation, exposure to ship engine sounds during daily travelling was the most likely cause. It was also revealed that several hours' exposure to the engine sounds was needed to detect a temporary threshold shift of hearing before and after work.

[A Japanese language version of the health-promoting lifestyle profile].

The development and initial psychometric evaluation of a Japanese version of the Health-Promoting Lifestyle Profile II (HPLP II) is described. The 52-item instrument was translated into Japanese and was found to be culturally relevant and reliable in a pilot study. The Japanese version was then administered to adiverse but predominantly Japanese group of 337 subjects residing in northern Japan. The Japanese version of the HPLP II was evaluated using factor analysis and reliability measurement. Six factors similar to those isolated previously during psychometric assessment of the English language version were extracted. Those six dimensions comprise the HPLP II subscales of: 1. Health responsibility, 2. Spiritual growth, 3. Physical activity, 4. Interpersonal relations, 5. Nutrition, and 6. Stress management. The alpha reliability coefficient for the total scale was 0.94 and the 2-week retest reliability was 0.91; the alpha coefficients for the subscales ranged from 0.70 to 0.87. The Japanese language version of the HPLP II appears to have sufficient validity and reliability for use by researchers who wish to describe the health-promoting components of lifestyle among the Japanese population and to explore differences and similarities in the health-promoting lifestyle of Japanese and American subjects or those of other ethnic groups. Further evaluations of measurement with different populations appears warranted. This instrument will enable researchers to investigate patterns and determinants of health-promoting lifestyle, as well as the effects of interventions to alter the lifestyle.

[An epidemiological study regarding the hearing acuity of residents in the area with high level of aircraft noise: results of hearing tests conducted in the vicinity of Kadena Air Base].

Hearing tests, primary and secondary, were conducted in two communities vicinal to Kadena US Air Base in Okinawa from May 1996 to July 1998. The noise exposure expressed in WECPNL as designated by the Defense Facilities Administration Agency ranged from 85 to 95 and above. A total of 2035 subjects aged between 25 and 69 years inclusive were considered eligible for inclusion in this study and among them 137 males and 206 females underwent the primary test. Before the test, subjects were asked about hearing difficulty, tinnitus, otological anamnesis and past experience of noise exposure at work and/or hobbies. The primary test was a pure tone audiometry using the ascending method of limits with 5 dB step at 7 test frequencies of 0.5 to 8 kHz. Forty individuals who were judged to have possible noise induced hearing loss were sent to Okinawa Chubu Hospital as subjects for the secondary test. The secondary test consisted of pure tone audiometry with 1 dB step at 9 test frequencies with the addition of 3 kHz and 6 kHz to the primary test frequencies, a Short Increment Sensitivity Index (SISI), test, tympanometry and audioscan audiometry. Based on test findings 12 subjects were considered to have noise induced hearing loss. The examiners interviewed the 12 subjects again to confirm that they had not experienced habitual or repeated intense noise exposure other than aircraft noise exposure around their homes. The geographical distribution of the subject's residences showed their proximity to the airfield, which strongly suggests that the cause of hearing loss may be exposure to aircraft noise from Kadena Air Base.

[Evaluation of hearing disorders and social support among the middle aged and elderly in the community. I. Analysis on the relationship between hearing difficulties and social participation, and self-rated health].

OBJECTIVES: To clarify the actual conditions of middle-aged and elderly community residents with hearing disabilities; and to investigate, through self-evaluation, the impact of hearing difficulties on health and social participation so that a key can be found to provide social support for residents with some degree of hearing impairment. METHODS: A questionnaire survey was conducted in Soyo village in Kumamoto Prefecture. The subjects of the survey were 2,199 residents aged 40 years and older receiving health check-ups in accordance with the Health Service Act for the Aged. The questionnaires consisted of 8 items regarding self-evaluations of health, hearing difficulties, the utilization of hearing aids, tinnitus, and social life. RESULTS: Data from 2,075 respondents who completed the questionnaire were analyzed. The results were as follows: 1. The number of residents claiming hearing difficulties according to age: 40 s--1 man (0.6%) 50 s--7 men (3.9%) and 7 women (2.8%) 60 s--26 men (8.3%) and 16 women (4.2%) 70 s(+)--42 men (17.5%) and 37 women (11.1%) The percentage of respondents suffering from hearing difficulties increased significantly with age with percentages higher in men than in women among all age groups. 2. Thirty-eight men and 32 women reported customary use of a hearing aid. Hearing aid use was 0.6% among men in their 40 s, 1.1% in men and 1.2% for women in their 50 s, 3.2% in men and 1.6% for women in their 60 s, 10.4% in men and 6.9% in women in their 70 s or older. 3. Logistic regression analysis showed a significant association between hearing difficulties and social participation (Odds ratio: 1.56; 95% Confidence Interval, 1.02-2.38). The degree of social participation (participation in a variety of activities/communication by telephone) was restricted by hearing difficulties. 4. Logistic regression analysis showed a significant association between hearing difficulties and self-evaluated health (Odds ratio: 2.47; 95% Confidence Interval, 1.38-4.42. The elderly with hering difficulties tended to show lower self-evaluated health. CONCLUSIONS: This study suggests the necessity of creating and implementing social policies that deepen residents' awareness of hearing disabilities as invisible barriers in the home, in the workplace, and in the community; and the necessity of improving the living environment through the utilization of barrier-free designs that will foster better communication.

[Survey of noise exposure level of national forestry workers].

Eighty-one national forestry workers who were using chain saws, log cutters, log cutting machines, bush cleaners, timber-collecting cable machines and forklifts were examined for their level of noise exposure in a working day by using a portable sound meter. And their noise exposure levels Leq (8 h) for a year were estimated based on the measured noise levels and on the number of noise exposure days and hours in a year recorded in their work documents. The survey was made from July to December, 1988. The maximum noise levels with all the machines except a case of the forklift were above 100 dB, and with most chain saws they were above 110 dB. The amount of time that workers were exposed to the noise of logging and lumbering with chain saws, cutting by bush cleaners and timber-collecting cable machines without a cabin was longer than the allowable time for 90 dB and 95 dB. The number of noise exposure days in a year is fewer than reported in the past. The estimated Leq (8 h) for 32 out of 34 lumbermen surveyed was more than 85 dB, and for 5 lumbermen the Leq (8 h) was more than 90 dB. From these results, it can be concluded that there is a danger of noise induced hearing loss in national forestry workers using chain saws, log cutters, log cutting machines and timber-collecting cable machines without a cabin in 1987.

A tentative proposal for classification of audiograms in noise-induced deafness: relationship between audiogram and subjective complaints in noise-exposed workers.

Audiograms obtained from workers exposed to occupational noise were classified into six stages, namely, "normal" and stages I-V of noise-induced deafness, using the audiometric chart and the classification table designed by the authors. Close correlations were observed between the severity of the stage and the degree of hearing in daily life, which support our classification method. On the other hand, the prevalence rate of tinnitus also showed a linear increase in proportion to the severity of the stage, although the mechanism of tinnitus in noise-induced deafness has not yet been elucidated. From the viewpoint of protecting workers from hearing damage due to noise exposure, further investigation is required to make the best use of our classification method in noisy workplaces.

[Acoustic reflex in workers using hand-held vibration tools. Combined effects of noise and local vibration].

Combined effects of noise and local vibration on the threshold of acoustic reflex (ART) were investigated. ARTs for three different stimuli (ARTWN, ART1k, ART4k) were determined in workers using hand-held vibration tools. The results obtained from these 72 workers (Group A) were compared with the ARTs in 100 control subjects (Group C) who had normal hearing acuity without any history of occupational noise exposure, as previously reported by the authors. The mean age in group A was 46.6 ranging from 26 to 62. The mean period of noise and vibration exposure was 11.4 years in subjects mainly using chain saws and 9.2 years in subjects mainly using bush cleaners (Table 2). ARTWN and ART1k in the exposed group showed significant differences compared to those in the non-exposed group (p less than 0.001), i.e., mean ARTWN was 89.6 dB SPL in Group A and 83.8 in Group C, mean ART1k was 96.1 dB SPL in the former and 92.2 in the latter group (Table 7). No significant difference was observed in mean ART4k between the two group (p greater than 0.1). The difference between ART1k and ARTWN, [ART1k-ARTWN], was significantly reduced in the exposed group (p less than 0.001), i.e., 2.7 dB in Group A and 12.4 in Group C (Table 8). To clarify the effects of aging on [ART1k-ARTWN], the exposed group was classified into three groups according to their HL(4k + 8k)/2. However, no significant correlation was observed between [ART1k-ARTWN] and age in any of these 3 groups (p greater than 0.1).(ABSTRACT TRUNCATED AT 250 WORDS)

Study on an evaluation index for noise susceptibility. I. Estimation of critical bandwidth in acoustic reflex.

A new method for estimating critical bandwidth in AR has been developed. The reflex activating sounds (RAS) consisted of a 1000 Hz pure tone, and thirteen kinds of noise centered on 1000 Hz with bandwidths of 100, 250 and 1/3-octave frequencies in 500 to 1000 Hz. A two-phase linear regression model was fitted to the sets of data which showed the relationships between the magnitude of acoustic reflex (AR) and bandwidth of RAS. The existence of a critical bandwidth was confirmed in 81 subjects with normal hearing acuity. The effects of bandwidth on magnitude of AR was not observed in two subjects, so critical bandwidth (CBW) was estimated at greater than or equal to 4000 Hz in their cases. The median value of CBW in AR was 1138 Hz in 83 subjects. Our new method, designed for practical use, may be a useful tool for estimating the critical bandwidth in AR.

Study on an evaluation index for noise susceptibility. II. Reduction of [ART1k-ARTWN] and critical bandwidth in acoustic reflex.

Effects of noise exposure on the difference between ART1k (acoustic reflex threshold) and ARTWN [( ART1k-ARTWN]), and on the critical bandwidth (CBW) in acoustic reflex (AR) were investigated. One hundred and eleven workers using hand-held vibrating tools (exposed group) served as subjects. The results were compared with the values obtained in the control group reported by the authors previously (Miyakita and Miura 1985). The exposed group was classified into four groups according to their hearing levels (HL) at 4 and 8 kHz; i.e. Group A (HL(4k + 8k)/2 less than 25 dB), Group B (25 dB less than or equal to HL (4k + 8k)/2 less than 50 dB), Group C (50 dB less than or equal to HL (4k + 8k)/2 less than 75 dB), and Group D (HL (4k + 8k)/2 greater than or equal to 75 dB). [ART1k-ARTWN] was reduced significantly (p less than 0.001) in the exposed groups; i.e. 12.4 dB in the control group, 6.7 dB in Group A, 2.3 dB in Group B, -0.3 dB in Group C, and -1.3 dB in Group D. On the other hand, a significant widening of the CBW was observed in the exposed group compared to that of the control group (p less than 0.05); i.e. 1138 Hz in the control group, 1410 Hz in Group A, 3287 Hz in Group B, and greater than or equal to 4000 Hz in Groups C and D. In addition, we confirmed that the reduction of [ART1k-ARTWN] might be the result of the widening of the CBW in AR.(ABSTRACT TRUNCATED AT 250 WORDS)

An experimental study of the physiological effects of chain saw operation.

This experimental study was designed to determine whether a combination of noise and vibration produced more pronounced changes in temporary shifts of finger skin temperature and temporary threshold shift (TTS) of hearing than those resulting from exposure to either stress alone. Nineteen healthy subjects were exposed to six different combinations of vibration, noise, and handle holding by using a chain saw for a pre-determined time. The mean value of normalised finger skin temperature decreased much more when the subjects operated a chain saw at high speed (exposure 1) than when they operated the chain saw with the noise isolated by double hearing protection (exposure 2). In five of the 14 subjects significantly larger TTS values at 4 kHz were observed in the former condition (exposure 1) compared with the values obtained when they stood beside someone else operating a chain saw (exposure 3). The results of this study suggest that noise may play a part in inducing the constriction of the peripheral vessels seen with local exposure to vibration, and that hand-arm vibration may produce an additive effect on the noise induced TTS.

Evaluation of noise susceptibility: effects of noise exposure on acoustic reflex.

The threshold of acoustic reflex (AR) was measured in workers exposed to occupational noise. White noise (WN), and pure tones of 1 and 4 kHz were selected as activating stimuli for AR. The results were compared with the thresholds of AR (ART) in the normal group (Group C) reported by the authors previously. To examine in relation between noise exposure and ART, the exposed group was classified into two groups by their hearing levels (HL) at 4 and 8 kHz; i.e. Group D (HL(4k + 8k)/2 less than 25 dB) and Group E (HL(4k + 8k)/2 greater than or equal to 25 dB). A significant (P less than 0.001) elevation of ARTWN was observed not only in Group E (8.8 dB) but also in D (7.5 dB) with normal hearing acuity. A significant (P less than 0.001) lowering of ART1k was observed in Group E only. The difference between ART1k and ARTWN, [ART1k-ARTWN], was reduced significantly (P less than 0.001) in the exposed groups; i.e. 12.4 dB in Group C, 3.7 dB in Group D and 0.6 dB in Group E. These results suggested that the value of [ART1k-ARTWN] may be used as a sensitive and objective indicator for detecting and evaluating the early stages of noise-induced hearing impairment and individual susceptibility to noise.

[Effects of ethyl alcohol ingestion on the disturbance of porphyrin metabolism by lead].

A study was made on the possibility of synergistic effects of ethyl alcohol and lead on porphyrin metabolism in rabbits. Experimental rabbits were divided into 4 groups. Group A was the control group not given any treatment, and the other 3 groups (Groups B, C and D) were treated with ethyl alcohol, lead, and ethyl alcohol and lead respectively, for 2 months. Ethyl alcohol solution (5%) was administered to rabbits in Groups B and D as drinking water on every weekday. The average dose of alcohol was 6 ml/kg/day (18 ml/cap/day). Lead was injected intravenously to rabbits in Groups C and D at a dose of 0.5 mg Pb/kg on alternate days (3 times per week). Furthermore, a large dose of Pb was administered to other rabbits (Group C'). In rabbits treated with alcohol alone (Group B), no effect was observed in the biochemical indicators related to porphyrin metabolism. In the groups treated with lead (Groups C and C') and with lead and alcohol combined (Group D), some biochemical changes in porphyrin metabolism developed with increase of Pb-B, i.e. increase of ALA-S activity and total porphyrin content in the bone marrow, elevation of FEP level, increase of ALA-U and CP-U, and decrease of ALA-D activity in erythrocytes. Comparison of Groups C and D showed that CP-U and ALA-U increased significantly in Group D, but no significant difference was observed between both groups in FEP and in ALA-S activity in the bone marrow and liver. The other laboratory measurements, such as total porphyrin contents in the liver and plasma, and GOT or GPT level in serum, showed no significant change in all the groups. In the present study, the biochemical changes suggesting synergism of lead and ethyl alcohol were observed slightly in ALA-U and CP-U but not in ALA-S and FEP. These results suggest that these changes are essentially due to lead rather than mutual enhancement of the direct effects of these two toxins on porphyrin metabolism. However, it still remains to be determined whether or not ethyl alcohol affects the liver and kidney functions which may be related to ALA and CP excretion.