Osmotic shock-induced neurite extension via activation of p38 mitogen-activated protein kinase and CREB.

Although it is known that sustained activation of classical mitogen-induced protein kinase (MAPK, also known as ERK) induced by nerve growth factor (NGF) plays an important role in the induction of neurite outgrowth, the role of p38 MAPK in neural cell function is still not clear. We developed two neuronal cell lines from PC12 cells, PC12m3 and PC12m32, in which NGF-induced neurite outgrowth is impaired and that show neurite outgrowth in response to hyperosmotic shock. The frequencies of neurite outgrowth of PC12m3 and PC12m32 cells induced by osmotic shock were approximately 10- and 12-fold greater, respectively, than that in PC12 parental cells. The p38 MAPK pathway inhibitor SB203580 but not the ERK pathway blocker U0126 inhibited the ability of PC12m3 and PC12m32 cells to induce neurite outgrowth in response to osmotic shock. Furthermore, expression of a nonactivable form of p38 but not that of wild-type p38 significantly blocked neurite outgrowth induced by osmotic shock. The extent of phosphorylation of p38 MAPK induced by osmotic shock in PC12m32 cells was much greater than that in PC12 parental cells. The upstream kinases MKK3 and MKK6, which phosphorylate and activate p38 MAPK, also showed higher levels in PC12m32 cells than in PC12 parental cells when treated with osmotic shock. Inhibition of p38 MAPK by SB203580 resulted in inhibition of the activity of the transcription factor CREB, which is activated by osmotic shock. These findings indicate that activation of CREB mediated by a p38 pathway distinct from the NGF signaling pathway may be required for neurite outgrowth.

Two distinct anti-allergic drugs, amlexanox and cromolyn, bind to the same kinds of calcium binding proteins, except calmodulin, in bovine lung extract.

In order to explore candidates for proteins required in exocytosis, we used two anti-allergic drugs, amlexanox and cromolyn, which inhibit IgE mediated degranulation of mast cells and basophils, as molecular probes in affinity chromatography. These two drugs chiefly bound to the same kinds of calcium binding proteins in bovine lung. These proteins were as follows: bovine calgranulin C homolog, an 8-kDa unknown protein, S-100L, calgranulin B, calcyphosine, and annexins I-V. The homologous affinity of the two drugs to these proteins is in accord with the similar anti-allergic property of both drugs. From these findings it is presumed that these drugs interact with these proteins and affect pharmacologically the degranulation.

A follow-up study of preventive effects on low back pain at worksites by providing a participatory occupational safety and health program.

Low back pain is still a common and serious issue at worksites. In order to evaluate preventive effects on low back pain by providing a participatory occupational safety and health program, we conducted a 10 year follow-up study at the Tokyo Metropolitan Bureau of Waste Management and examined yearly changes in the number of compensated and claimed low back pain. The participatory occupational safety and health program is based on a small-sized group and joint employee-employer involvements. This program includes analysis of occupational accidents, revision of the safety procedure manual, participatory training classes, improving and evaluating working procedures and personal protective equipment , and so on. The number of compensated low back pain from 1984 to 1994 has decreased from 318 to 87, and the number of claimed low back pain has decreased from 343 to 92. These results suggest that the participatory occupational safety and health program is effective in prevention of low back pain.

Improving workplace environments and working conditions at worksites providing school lunch service in Japan.

With the cooperation of All Japan Prefectural and Municipal Workers' Union, we have started an overall program on occupational safety and health from 1984. This program has several strategies aimed at preventing occupational injuries and work-related diseases. At first, we analyzed the relationship between work-related hazards and occupational factors, and to identify dangerous or hazardous factors in the workplace. Second, we have conducted a couple of intervention studies at worksites and evaluated these improvements. Third, we discussed the priority, feasibility and cost of improvements with Workers' Union members and school lunch workers. Fourth, during the last decade, Workers' Union and many researchers have demanded that regulations be implemented which would establish comprehensive safety and health programs. Fifth, we provided the workers with procedures on how to improve working environments and conditions. These education and training programs are provided for small-group working ("safety and health circle"), and demonstrate to workers their abilities to solve occupational safety and health problems and to empower them with respect to health-related issues. Finally, we discussed and evaluated the preventive effects of improving workplace environments and working conditions. The overall program on occupational safety and health at worksites is developing nationwide and is gradually taking effect.

The effects of frequently rotating shiftwork on sleep and the family life of hospital nurses.

The effects of three frequently rotating shifts in an irregular sequence on the daily activities of 239 Japanese female hospital nurses were studied by the time-budget method. The nurses recorded their daily activities for several consecutive days. The questionnaire was returned by 80.8% of the participants, and recordings of 1016 days were analysed. A two-way analysis of variance clarified that the shift combination influenced the daily activities. The most distinct result was that nurses spent significantly more time on free-time activities on the day when they worked the night shift followed by the evening shift than they did on the day when they worked any other shift combination. Nurses offset sleep deprivation either by sleeping during the day before and after working the night shift (82-100%) or by sleeping 2 to 4 h later in the morning after working the evening shift and on days off. There was a strong positive correlation between total sleep time (including day sleep) and the length of the interval between two consecutive shifts (r = 0.95, p < 0.001). This result suggests that more than 16 h between work shifts is required to allow more than 7 h of total sleep time. In an analysis by household status, nurses who had young children (average age, 2.8 years) slept less and spent less time on free-time activities than did other nurses.

Biomechanical studies on newly tailored artificial dental root.

Artificial roots must carry multiple forces during mastication. Stress distribution around a root depends upon the shape, material, and function of the root. Therefore, for biomechanical studies on artificial roots, triad research on the material, shape, and functional effect upon surrounding tissue is essential. For dental implants, there are two different functional systems against the masticatory force, i.e., gomphosis and ankylosis on osseointegration. Stress analyses of functioning new type (gomphosis) artificial roots were carried out in mandibular and maxilla models to study the triad effect using finite element analysis. The authors have already reported histological and biomechanical studies on the shape and functional effect. To observe the material effect biomechanically, artificial roots made of sintered hydroxyapatite and zirconium oxide were analyzed in the models. Thereafter, animal experiments using dogs were carried out to observe bone formation around artificial roots made of hydroxyapatite and zirconium oxide in the mandible and maxilla. The following results were obtained: The patterns of stress distribution around artificial roots of two different materials were not too different, and were exclusively dependent upon the root shape and structure of the jawbone. Around the artificial roots, bone formation coincided with a moderate stress distributing zone and principal stress trajectories. Through these experiments, the following conclusions were obtained: (a) Osteogenesis around artificial roots coincides with the stress distribution patterns. (b) Stress distribution patterns are dependent very little upon material properties but upon both the artificial root shape and the structure of the jawbone. (c) Optimization of the artificial root shape can be obtained by FEA in the models.

Biomechanical research on junction system of bone with biomaterials.

Regarding the junction of bioceramics with original bone, which have quite different material constants of Young's modulus and Poisson's ratio from each other, synostosis (ankylosis) cannot be obtained under severe loading conditions. Therefore, it is necessary to introduce a new junction system for the interface between the biomaterial mechanical organ and original bone. The jointing system of dental root to jawbone reflects on the function against mastication. The interface between different mechanical organs with different materials necessitates a specific juncture system under severe loading because of the disparity of material constants. The authors already reported the result of studies on the shape effect of artificial roots in functioning jawbone by means of finite element analysis. Studies on the functional effect of artificial roots in undulated shape were carried out biomechanically by means of finite element analysis using models to investigate an effective juncture system between bone and biomaterials. The results of finite element analysis were compared with the findings obtained from histological specimens. To observe the juncture state of bioceramics with tubular bone cortex, tubular apatite artificial bone was implanted in the femur of a dog. From these studies, the following results and conclusions were obtained: (a) The fibrous juncture system around bioceramics has an important role, after which the principal stress trajectories are converted; and (b) optimal undulated morphology compatible to the artificial bone's juncture system by means of fibrous ligament is essential for remodeling of the bone around the artificial skeletal bone.

Biomechanical studies on shape effect of hydroxyapatite artificial root upon surrounding jawbone.

To study the shape effect upon surrounding tissue of artificial dental root made of synthetic hydroxyapatite, this paper deals with the numerical analysis of the artificial root on functioning jawbone with the aid of the finite element method (FEM). The stress distribution around artificial roots in the shape of a cylinder, a cone, and three types of corrugated cone, including the newly tailored type implanted in the mandibular molar region, was analyzed in the plane strain state. The numerical results showed that the stress distribution was sensitive to the artificial root shape, and that the stress state was distributed in mitigatory way around the roots of the newly tailored form. The pattern of osteogenesis in the animal experiment and the finite element analysis (FEA) pattern showed a close correlation. Osteogenesis was assumed to occur in the weak or moderate stress distribution zone. The principal stress trajectory pattern in the lamina dura around the tailored artificial root was indicated as being either parallel or normal to the root surface. From this study, the biomechanical property of the tooth can be identified as a vehicle of mastication forces which disperse stresses moderately and equally upon surrounding tissues. Also, the periodontal ligament can be identified as a converting system of principal stress trajectories.

[Occupational dust exposure and prevalence of respiratory symptoms among conduit repair workers].

The amount of water supply in Japan was 16 billion ton as of 1989. Water from rivers and other sources is purified, sterilized and then supplied to the residents through conduits. When conduits are accidentally damaged, they must be repaired by the workers of the Waterworks Bureau of the local government. In this task, the workers are exposed to airborne dust which develops while digging and filling the ground and cutting the conduit and the concrete covering the road. The purpose of the present study was to estimate the airborne dust exposure level among the workers and to investigate its effect on their respiratory organs. First, we measured the total dust exposure concentration of 20 conduit repair workers and the total dust concentration in 10 office rooms. Second, we conducted a self-administered questionnaire survey to estimate the prevalence of respiratory symptoms among the employees of 119 Waterworks Bureaus. The subjects of the analysis were 322 conduit repair workers and as their controls 345 clerical/engineering workers. The results can be summarized as follows: 1) The average daily total dust exposure while repairing conduits ranged from 0.27 to 5.05 mg/m3 (mean = 0.91 mg/m3), while that while exchanging water meters from 0.23 to 0.52 mg/m3 (mean 0.41 mg/m3). These values were 4.6 and 2.1 fold higher than the total dust concentration in office rooms (mean = 0.20 mg/m3). 2) With the use of fluorescent X-ray method, iron and aluminum were detected in all samples collected while repairing conduits and the intensity of X-ray increased with increase in weight of collected dust. Iron exposure concentration ranged from 0.006 to 0.095 mg/m3, which is much higher than the levels in the air in urban areas. Iron and aluminum could not be detected by fluorescent X-ray method in most of the samples collected in office rooms. These findings indicate that the main element in the dust collected while repairing conduits is soil, while that in office rooms is tobacco smoke. 3) Among the smokers, the prevalence of cough and phlegm was significantly higher in conduit repair workers than in clerical/engineering workers. A similar tendency was observed among ex-smokers and non-smokers, but the difference was not significant.

[Estimation of asbestos exposure among workers repairing asbestos cement pipes used for conduits].

Asbestos cement pipes (ACPs) containing 15 to 20% chrysotile or crocidolite have been used for underground conduits. Even today 16.2% of all conduits in Japan are ACPs, though the production of ACPs was suspended in 1985. When such a conduit is accidentally damaged the workers belonging to the Waterworks Bureau of a local government cut off the damaged conduit using a high-speed disk cutter and replace it with a new conduit. This operation develops a cloud of dust and the workers involved run the risk of asbestos exposure. It was the aim of the present study to estimate asbestos exposure levels among these workers. First, in the experiment, we established the typical working conditions and requested an experienced worker to cut an ACP using a high-speed disc cutter in a hole dug in the ground as he routinely does. The experiment was repeated three times. During a bout of each experiment, dust was sampled at several points both inside and outside the hole. Second, a self-administered questionnaire survey was conducted to obtain information from the workers regarding their working conditions in cutting ACPs. The subjects of the survey were 1,048 men belonging to conduit repair sections of the Waterworks Bureau of 119 local governments. The results obtained can be summarized as follows. 1) Each bout of cutting ACPs required about five minutes. The concentration of asbestos fibers longer than 5 microns with 3:1 aspect ratio ranged from 48 to 170 fibers/ml (92 fibers/ml on an average) inside and 1.7 to 15 fibers/ml outside the hole. The concentration inside the hole exceeded the ceiling limit (10 fibers/ml) recommended for asbestos by the Japanese Association of Industrial Health. A concentration of 92 fibers/ml is equivalent to 0.96 fibers/ml as 8-h time-weighted average. 2) The number of subjects with experience of cutting ACPs was 849 (81.0%). The average length of service in conduit repair section was 14.2 yr. Based on the information obtained from each subject regarding the average working days per yr for each decade from 1946, the cumulative days to date expended in cutting ACPs was estimated to average 235 d, that is, 17 d per yr. Only 18.1% of the subjects used a protective respiratory device.(ABSTRACT TRUNCATED AT 400 WORDS)

[An epidemiological study on low back pain and occupational risk factors among clinical nurses].

Recently medical services and nursing system are being reformed due to high medical costs and shortage of clinical nurses. The shortage of clinical nurses influences not only their working conditions but also their own health problems. In European countries and the United States, low back pain (LBP) has been reported to be one of the most common and costly health problems among clinical nurses. To estimate the occupational risk factors of LBP among nurses, a questionnaire survey of LBP and occupational risk factors was carried out in 1987 on 947 clinical nurses and as well as on 300 female clerical workers of three local governments. First, to examine the prevalence and the magnitude of the problem, we analyzed several kinds of prevalence rates of LBP and its characteristics among nurses and clerical workers. Second, a case-control study was conducted to investigate the relationship between LBP and occupational risk factors. In analyzing occupational risk factors of LBP, odds ratios, age adjusted odds ratios and 95% confidence intervals were computed. Finally, to estimate simultaneously the effect of multiple risk factors of LBP and to confirm univariate age adjusted odds ratio analyses, several multivariate analyses were performed. Point, period (a month), and lifetime prevalence rates of LBP and prevalence rate of severe LBP among clinical nurses were significantly higher than those of clerical workers (p less than 0.05-0.001, respectively). Demographic and occupational items, such as being an assistant nurse (as opposed to a registered nurse), and working in certain departments (internal medicine, orthopedic surgery, neurosurgery, psychiatry, tuberculosis ward) showed significantly higher odds ratios for LBP (p less than 0.05-0.001, for all). Many items pertaining to working conditions connected with shift work, hospitalized conditions of patients, taking breaks and holidays, working postures, weight of patients and equipment lifting and moving, working environments and so on had significantly elevated age adjusted odds ratios (p less than 0.05-0.001, for all). Intensity of work loads estimated subjectively such as 'caring for patients who are in bed', 'supporting patients when transporting and bathing them', 'preparing drugs and injections, and treating', 'observing and monitoring patients' conditions', 'instructing and explaining procedure to patients and their family' and so on also had significantly elevated age adjusted odds ratios (p less than 0.05-0.001, for all). Moreover, many items on the problems connected with working life and interpersonal relationships showed significantly higher age adjusted odds ratios (p less than 0.05-0.001). In multivariate analyses, independent variables which made a significant contribution to the model were similar to the items which had significantly elevated age adjusted odds ratios.(ABSTRACT TRUNCATED AT 400 WORDS)

Reproducibility of pitch-matching test for tinnitus. Using a heptatonic scale.

We evaluated the reproducibility of measured values obtained using a heptachord pitch-matching test (PMT). Investigation of the measured values by considering the minimum unit width limits of the testing scale revealed that the coincidence ratios of the measured values of intra-daily variations, intra-weekly variations and eight values measured consecutively in one test were as high as 100%, 94.8% and 83.3%, respectively. We therefore concluded that the reproducibility of this method is satisfactory. The measured values obtained by both ordinary one-octave-interval and heptachord PMT are compared in this article.

Studies on motion sickness caused by high curve speed railway vehicles. Evaluation of the swing and its effects on passengers and conductors.

The high curve speed railway vehicles (HCSRVs) of the Japanese National Railway have been operating since 1973 with the aim of increasing speed on ordinary routes with many curve track sections. Although the aim of increased speed has been attained, it has been pointed out that the swing of HCSRVs is stronger than that of ordinary-type trains and it may increase motion sickness among the passengers and conductors. In this study, the authors examined motion sickness symptoms among 119 passengers and 100 conductors of both trains with a self-administered questionnaire, and evaluated the vibration acceleration on the floor by using the 1/3 Octave Band Analyzer and the Fast Fourier Transform method (FFT). The results can be summarized as follows: There were more passengers and conductors suffering from motion sickness riding on HCSRVs than those on the control trains. HCSRVs had the peak values of vibration acceleration within the range of 0.5 Hz and 1 Hz at horizontal, although the control train showed them above 1.0 Hz. These results suggest that the high rates of subjective complaints of passengers and conductors riding on HCSRVs were affected by vibration acceleration of frequency lower than 1 Hz.

Comparative study of the work load between one-man buses and two-man buses.

The differences in physiological and safety conditions of one-man buses and two-man buses were examined from the view point of occupational fatigue. This survey consisted of a work load study which included a time study, study of subsidiary behavior, auditory task, memory test, Galvanic Skin Response (GSR) and physiological function tests and a self-administered questionnaire which involved items concerning safety and subjective fatigue complaints. The visual and postural restrictions in the one-man bus were greater than in the two-man bus. The mental capacity of the one-man bus drivers was found to be less. Greater mental fatigue and stress were observed in the one-man bus. More subjective fatigue complaints were observed in the one-man bus. More cases of near accidents were observed in the one-man bus. From these results it was concluded that the one-man bus caused bus drivers a greater mental and physical work load.

Effects of consecutive night-shift work on health conditions among car-cleaners of super-express trains.

The Shinkansen Super-Express trains of the Japanese National Railways, the so-called bullet trains, run from early morning until late at night. Accordingly the car-cleaners of the Shinkansen must do late night shift work. A self-administered questionnaire survey including items about health and work conditions was given to 246 workers at Osaka Station, who were then divided into 3 groups: Group A consisted of 102 night workers working 5 successive days with 2 days off, Group B consisted of 124 alternate-day 24-hour workers working 3 days a week, while Group C included 20 day-workers working 6 days a week. A subjective fatigue inventory was administered before and after work for a week to 20 workers selected from each of three groups, group A, B above group D whose shift was 2 times 2 successive night shifts with one day off, and one holiday a week. The results of the questionnaire survey revealed that the rates of complaints such as gastroenteric disorders and general fatigue were the highest in group A. The results of the subjective fatigue inventory show a tendency for the number of complaints in group A and B to increase significantly after the last work shift of the week, but not in the case of group D. The authors demonstrated that there was a close relationship between patterns of night-shift work and various kinds of health problems, and concluded that to insert a day off on the third day of the group D shift was effective in reducing the work load.

Occupational health hazards resulting from elevated work rate situations.

Some occupational health hazards resulting from an elevated rate of work due to recent mechanization and automatization are discussed on the basis of results of health examinations. A rapid increase of a cervicobrachial disorder among young cash register and packing machine operators has been observed. Switching to the use of electronic cash registers has been shown to have only limited efficacy due to increased operation speed, and high-speed complex finger and hand movements of packer operators have also proven to be as hazardous as key-board operations. The high incidence of low-back pain, in particular gradually developing pain, among workers in electric power supply work has been suggested to be the result of quick and intensified work to meet increasing supply demand. Likewise, the workload of electric locomotive and bullet train drivers has increased in accordance with increased train speeds, and has been shown to have had significant effects on their health particularly in regards to neural strain, intra-cab environment such as air pressure change, vibration, and noise, and rotation on irregular shifts. New steps seem required therefore to meet the new health problems arising from a combination of modern technological changes and elevated working speeds.