A cross-sectional study was conducted to clarify the relationship between type A behavior pattern and life styles on 669 male and 60 female workers belonging to a financing company. A self-administered questionnaire was used to collect information on type A behavior pattern (including 11 questions), medical parameters and recent well-being. Principal component analysis was made to select the three major components concerning type A behavior pattern. The first component score represented overall irritability, the second score relaxation, and the third score etiology of irritability.
After these component scores were adjusted to age, the following findings were observed. Smoking habits and heavy alcohol intake showed a significant correlation with a high score in the first principal component. General feeling during the past month and fatigability were related to the first and second principal component scores, respectively. Discouragement, bad arousal, little worth of living and apathy were negatively related to the second principal component score. Total cholesterol showed a positive correlation with the second principal component score (r=0.140, p<0.01) in males and obesity index had a positive correlation with the second component score (r=0.259, p<0.01) in females. Other medical parameters including high density lipoprotein, systolic and diastolic blood pressure did not demonstrate any significant correlation with principal component scores. It is important that recognition of type A behavior pattern may be applied to health education programs.

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The health status of 59 wives of seamen during their absence from home being on board a ship was evaluated by THI (Tokyo University Health Inventory). There was no evidence that the absence of their husbands had any undesirable effects on their health, but those who received fewer telephone calls from their absent husbands complained more frequently of subjective symptoms related to mental problems. The same tendency was observed in those who sought advice from their neighbors and others at times of trouble with their children. A qualitative analysis of communication between the wives of seamen and their husbands or other social network and evaluation of the mother-infant relationship should be conducted in the future.

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Four mail questionnaire surveys were conducted on the incidence of aplastic anemia among industrial workers throughout Japan in collaboration with industrial doctors during a period from 1970 to 1983. The following major results were obtained.
1. Response rates were 55.5% (874/1, 574 enterprises) in the first mail questionnaire survey in 1970-1972, 65.3% (294/450) in the second survey in 1973, 49.1% (170/346) in the third survey in 1976-1980, and 76.6% (242/316) in the fourth survey in 1981-1983. There was no significant difference in industrial types among the four surveys.
2. The numbers of aplastic anemia patients newly diagnosed were 145 (112 males/33 females) in the first survey, 21 (16/5) in the second survey, 51 (41/10) in the third survey and 30 (24/6) in the fourth survey. Incidence rates per million were 14.7 (14.4 males/15.5 females) in the first and second survey, 14.2 (13.5/18.3) in the third survey and 9.1 (8.6/11.9) in the fourth survey. The rates were almost constant from 1970 through 1980, but the rates decreased thereafter. The rate was higher in females than in males, but the difference was not significant.
3. Incidence rates were high in rubber industry (26.8 per million), paper industry (24.8), and petroleum industry (22.5), but there was no industrial type demonstrating a constantly higher incidence in every survey. Manufacturing industries showed a higher incidence (14.6) than non-manufacturing industries (11.7).
4. By type of work, non-productive work (67.2%), i.e., clerical (30.8%), administrative (8.9%), technical (7.7%), were the main jobs of 247 registered aplastic anemia patients (193 males and 54 females).
5. Thirty patients had been exposed to noxious agents such as organic solvents (21 cases including 3 exposed to benzene), metals (6), and radiation (1). However, in these cases no causal relationship between exposure and disease onset could be demonstrated.
6. Thirty-nine cases had a drug-intake history before onset of the disease. Drugs given included chloramphenicol (4 cases), other antibiotics (4), antituberculosis agents (8), analgesics (6), and tranquillers (4).
The results obtained revealed no positive evidence that occupational factors peculiar to Japanese industries were involved in triggering aplastic anemia.

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Forty-three workers exposed to low levels of toluene diisocyanate (TDI) during the process of producing polyurethane forms were examined immunologically for IgG, A, M, and E and serum enzyme activities such as serum angiotensin converting enzyme (SACE), serum lysozyme (SLZM) and glycylproline dipeptidyl aminopeptidase (GP-DAP). Air concentration of TDI was annually measured in various places of work during the past five years from 1979 to 1983. The results obtained in the present study were as follows.
1. The air concentration of TDI at all places of work was below the permissible concentration level of 0.02 ppm throughout the study period.
2. Subjective symptoms and abnormal findings on chest X-ray considered directly related to TDI exposure were not observed.
3. No remarkable abnormal findings in blood cell counts and in serum biochemical studies could be seen in any of the workers.
4. The serum IgG levels in workers directly exposed to TDI were significantly higher (p<0.05) than those in workers indirectly exposed to TDI and in non-exposed workers.
5. In the study of serum enzymatic activity, SLZM activity in workers exposed directly to TDI was significantly higher (p<0.01) than those in workers indirectly exposed to TDI and in non-exposed workers.

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To evaluate the function of the central nervous system of patients with occupational vibration disease, electroencephalograms and auditory brainstem responses (ABR) were recorded in 20 male subjects with occupational vibration disease whose age ranged from 46 to 67 years (mean 57.4 yr). All the subjects had operated chain saws from 10 to 25 yr (mean 15.2 yr) and had frequently complained of many subjective symptoms induced by central nervous system disturbances such as headache, head heaviness, tinnitus, vertigo, and insomnia, which corresponded to stage 3 in the diagnostic criteria of Andreeva-Galanina. Twenty-six healthy men whose age ranged from 40 to 67 yr (mean 53.0 yr) were selected as controls. Electroencephalograms were recorded with a 12-channel electroencephalograph, using unipolar and bipolar leads. Auditory brainstem responses were recorded by signal averaging technique using 100 μs alternating clicks. The stimuli were presented at 70 dB above threshold (SL) with a rate of 10 per second. The following results were obtained.
1. By electroencephalography, the incidence of diffuse alpha pattern, slow alpha wave and drowsy pattern was 32%, 32%, and 42%, respectively.
2. Click thresholds in the patients were obviously higher than those in the healthy controls.
3. The occurrence rate of wave II of ABR in the patients (61.8%) was significantly lower than that in the healthy controls (85.0%) (p<0.05).
4. The interpeak latencies I-V and III-V of ABR in the patients were significantly longer than those in the healthy controls. These findings suggest that the conduction velocity of brainstem auditory tract is reduced in the patients.
5. In the patients, the peak latencies and interpeak latencies of ABR waves were negatively correlated with the click thresholds. Therefore, delay in the interpeak latencies I-V and III-V does not indicate the severity of hearing impairment.
6. The interpeak latencies I-V and III-V in patients who always complained of tinnitus were significantly longer than in those who sometimes complained of tinnitus or did not at all. Thus a close relationship between delay of interpeak latencies and severity of tinnitus was suggested.
These findings suggest that these examinations are useful in evaluating the function of the central nervous system in patients with occupational vibration disease.

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Conduction disturbances in the central nervous system (CNS) of rats due to 2, 5-hexanedione (2, 5-HD) were examined, using auditory brainstem responses (ABRs). Ten male rats (Jcl-Wistar) were given subcutaneous injection of 2, 5-HD of 300 mg/kg/day five days a week for three weeks. For the control group, ten male rats (Jcl-Wistar) were employed. One week after the last administration, ABRs in rats were recorded at the scalp with subcutaneously inserted needle electrodes using the monopolar method under anesthesia. Intensity of the click sound stimulation was 25 dB and 60 dB over the threshold of human hearing level (25 dBHL and 60 dBHL). Mixed nerve conduction velocity of the caudal nerve (MNCVca) and somatosensory cortical evoked potentials by electrical stimulation at the forepaw and medulla oblongata (SEP and SEP-M) were simultaneously recorded.
The significant findings observed in rats administered 2, 5-HD in comparison with the control rats were as follows:
1) Delayed latencies of Ist, IInd, IIIrd, IVth and Vth components of 60 dBHL sound ABR and Ist, IIIrd, IVth and Vth components of 25 dBHL sound ABR; 2) Increased interpeak latencies (IPLs) between Ist and Vth components, IIIrd and Vth components, and IVth and Vth components of 25 dBHL sound ABR and between Ist and Vth components of 60 dBHL sound ABR; 3) Delayed latencies of P1 and N1 components of SEP; and 4) Decreased MNCVca.
Prolongation of IPL between IVth and Vth components of 25 dBHL sound ABR was considered to be conduction disturbance of auditory afferent pathway in CNS. The present results on SEP confirmed the previous finding that nerve conduction function in somatosensory afferent pathway was damaged by 2, 5-HD. The results of ABR indicate that measurement of ABR is a sensitive method to detect early disturbance of nerve conduction in CNS by neurotoxic substances which cause the dying back type axonopathy.

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