Job strain and changes in the body mass index among working women: a prospective study.

OBJECTIVE: The relationship between job strain and weight gain has been unclear, especially for women. Using data from over 52,000 working women, we compare the association between change in job strain and change in body mass index (BMI) across different levels of baseline BMI. SUBJECTS/METHODS: We used data from participants in the Nurses' Health Study II (n=52,656, mean age=38.4 years), an ongoing prospective cohort study. Using linear regression, we modeled the change in BMI over 4 years as a function of the change in job strain, baseline BMI and the interaction between the two. Change in job strain was characterized in four categories combining baseline and follow-up levels as follows: consistently low strain (low at both points), decreased strain (high strain at baseline only), increased strain (high strain at follow-up only) and consistently high strain (high at both points). Age, race/ethnicity, pregnancy history, job types and health behaviors at baseline were controlled for in the model. RESULTS: In adjusted models, women who reported high job strain at least once during the 4-year period had a greater increase in BMI (ΔBMI=0.06-0.12, P<0.05) compared with those who never reported high job strain. The association between the change in job strain exposure and the change in BMI depended on the baseline BMI level (P=0.015 for the interaction): the greater the baseline BMI, the greater the BMI gain associated with consistently high job strain. The BMI gain associated with increased or decreased job strain was uniform across the range of baseline BMI. CONCLUSIONS: Women with higher BMI may be more vulnerable to BMI gain when exposed to constant work stress. Future research focusing on mediating mechanisms between job strain and BMI change should explore the possibility of differential responses to job strain by initial BMI.

Associations between work schedule characteristics and occupational injury and illness.

BACKGROUND: Nurses often endure working irregular day, night and evening shifts as well as mandatory overtime (i.e. employer-imposed work time in excess of one's assigned schedule). While these work characteristics are examined as potential risks for nurses' safety and health, it is not clear whether negative health impacts occur simply because of working long hours or in combination with other mechanisms. AIM: This study investigates how these work characteristics are associated with nurses' work-related injury and illness over and above long work hours. METHODS: In this cross-sectional study, questionnaire data were collected from a sample of 655 registered nurses in the Philippines. Multiple logistic regression was used to assess associations of shift work and mandatory overtime with four work-related health outcomes. RESULTS: After weekly work hours, shift length and demographic variables were accounted for, non-day shifts were associated with work-related injury [odds ratio (OR) = 1.54; 95% confidence interval (CI): 1.07, 2.24] and work-related illness (OR = 1.48; 95% CI: 1.02, 2.16). Also, frequency of working mandatory overtime was associated with work-related injury (OR = 1.22; 95% CI: 1.06, 1.41), work-related illness (OR = 1.19; 95% CI: 1.04, 1.37) and missing more than 2 days of work because of a work-related injury or illness (OR = 1.25; 95% CI: 1.08, 1.44). CONCLUSIONS: These findings suggest that non-day shifts and mandatory overtime may negatively impact nurses' health independent of working long hours. Mechanisms through which these work characteristics affect health, such as circadian rhythm disturbance, nurse-to-patient ratios and work-family conflict, should be examined in future studies.

The retroperitoneum protects prosthetic graft material from intraperitoneal contamination: an experimental study.

OBJECTIVES: To evaluate the ability of the retroperitoneum to serve as a barrier, against bacterial contamination, between the peritoneal cavity to the retroperitoneal space. METHODS: Seventy rats had a small piece of knitted Dacron graft placed in the retroperitoneal space and 10(6)-10(9) colony forming unit (cfu) Enterococcus faecalis was injected into the peritoneal cavity. In half the retroperitoneal (RP) group, the retroperitoneum was preserved and in the remainder, the open peritoneal (OP) group, needle holes were created. Grafts were harvested after 1, 4, or 7 days and cultured for E. faecalis. A blood sample was collected from three rats in each group for culture before the graft was harvested. RESULTS: Graft infection did not develop in any rat injected with 10(6) or 10(7) cfu in the RP group, while seven out of the 10 graft cultures of the OP group grew E. faecalis (P = 0.003). In rats injected with 10(8) or 10(9) cfu, five out of the 10 graft cultures in the RP group and eight out of 10 in the OP group grew E. faecalis. All blood cultures were negative when the injected bacterial count was 10(7) cfu or less. One out of the three blood cultures was positive at 10(8) cfu, and all were positive at 10(9) cfu. CONCLUSIONS: These results suggest that an intact retroperitroneum acts as a protective barrier against intraperitoneal bacterial contamination, particularly when blood cultures are negative.

Effective prevention of carotid artery atherosclerosis by following this motto for healthy habits: "Give up one, reduce two, and increase three".

OBJECTIVES: Lifestyle has a major influence on the development and progression of atherosclerosis. Our motto for healthy habits is "give up one, reduce two, and increase three". The one thing that is to be given up is smoking. The two things that are to be reduced are intake of food and alcohol. The three things that are to be increased are exercise, rest and enjoyable activities. We assessed correlation between these six health habits and plaque score indicating degree of atherosclerosis in the carotid artery. METHODS: Subjects were divided into unfavorable (practicing zero to three habits) and optimal (practicing four to six habits) healthy habits groups. RESULTS: Plaque score was significantly higher in the unfavorable group (7.6 +/- 5.8) than in the optimal group (4.9 +/- 4.2) (P<0.001). CONCLUSIONS: The healthy habits that significantly contributed to prevention of atherosclerosis were quitting smoking and increasing rest and enjoyable activities.

Changes in circadian rhythm in heart rate and parasympathetic nerve activity after an eastward transmeridian flight.

Distortions of the circadian rhythm structure of the heart rate and parasympathetic nerve activity after an eastward transmeridian flight were studied. We recorded the ambulatory electrocardiograms of 12 healthy young men for 11 days: 3 days in Tokyo before the flight and 8 days in San Francisco following it. Heart rate variability was determined by power spectrum analysis, and high frequency power (0.15-0.4 Hz) was used as the index of parasympathetic tone. The structural characteristics of the circadian rhythm were analyzed by dividing consecutive RR data into four parts: the preflight days, the second and third days, the fourth and fifth days (Days 5-6) and the sixth and seventh days. Eight of the 12 cases were analyzed completely. The circadian period of the heart rate decreased after the flight. The peak time of parasympathetic nerve activity shifted from the small hours to the daytime, the maximum shift being during days 5-6 after the flight. We concluded that a structural disturbance of the circadian rhythm of the heart rate and parasympathetic nerve activity were observed.

[Impact of indirect factors on the growing prevalence of workers with abnormal findings in periodic general health examinations: a survey on the definition and detection of such abnormal workers by occupational health organizations].

The prevalence of workers with abnormal findings in periodic general health examinations (PGHEx) has been growing recently in Japan and reached 41.2% in 1998. To clarify the indirect factors related to such an increase in workers with abnormal findings in the PGHEx, we carried out a questionnaire survey on the content of the statutory notification form of results of the PGHEx among a representative sample of 136 Occupational Health Organizations (OHOs). Questions on how those workers with abnormal findings were defined and detected and when the definition and the reference intervals for total cholesterol became available were included. Of the 107 OHOs which answered the questionnaire, 85 were included in the analyses because they actually calculated the number of workers with abnormal findings in each company and helped the employer fill out the notification form. The results revealed that there was no standardized definition of workers with abnormal findings in the PGHEx. Both reference intervals of items in the PGHEx and algorithm in detecting workers with abnormal findings in the PGHEx varied among the OHOs. When detecting the workers, 13 OHOs (15.3%) selected them taking into consideration medical background factors such as previous results of the PGHEx and current medical treatment. From the late 1980s to the early 1990s, many OHOs modified the definition of workers with abnormal findings, and have tended to reduce the upper limit of the reference interval for serum cholesterol. This is mainly due to amendment of the Industrial Safety and Health Law and a new recommendation for a reference interval/value proposed by the related scientific society. Although the prevalence of workers with abnormal findings in the PGHEx has continuously increased, it is not valid to compare the prevalence over the years because of modification in the definition of such workers. The prevalence of workers with abnormal findings in the PGHEx, which is one of the most important indices of the state of occupational health, should be measured by using an objective definition and be compatible with the future system of health examination for Japanese workers.

[An investigation on ethylene oxide sterilization management in medical institutions].

The present study describes an investigation on the use and management of ethylene oxide (EO) which is used mainly as a sterilant in medical institutions in a Cabinet-order designated city. Information was obtained from a self-administered questionnaire on safety and health matters related to sterilization with EO gas. The questionnaire was sent to 189 medical institutions including major hospitals and randomly selected clinics. 127 questionnaire were returned and the analysis was carried out for 120 respondents, excluding seven respondents whose answers were found to be inappropriate. The proportion of medical institutions, employing more than 50 workers, in which an occupational health physician and/or health supervisor was appointed was 70% and was lower than for other industries. 1.6% of the employees engaged in EO sterilization activities in the hospitals, whereas in clinics the percentage was as high as 20%. Several problems were found both in the management and work methods with EO: operations were not isolated in 46%; gas leaks and back-streaming of exhaust gas were found in 59% and 41%, respectively; and personal protective clothing was not used in 69%. Improvement was found only for three items among the institutions where an occupational health physician was appointed. These results suggest that good workplace controls and practices are essential for medical institutions using hazardous materials including EO for sterilization.

[Implication of health checkups of students from developing countries in Japan].

We investigated the prevalence of peripheral blood abnormalities, parasitic infestation, and hepatitis virus infection, by using the results of the primary screening health checkups for 423 students (male: 317, female: 106, average age +/- SD: 34.2 +/- 5.5 year-old) from abroad. Most of them were from Southeast Asia, Africa, Central and South America, and other developing countries in tropical or subtropical areas. Thalassemia-like hematological disorders, showing microcytic peripheral red blood cells without any anemia, were seen in 7.6 percent of the students, and intestinal parasites were revealed in 12.7 percent of them. The positive rate for anti-hepatitis A virus antibodies (84.3%) and the exposure rate of hepatitis B viruses (35.3%) were similar to previous reports. Compared with the positive rate for anti-hepatitis C virus antibodies (anti-HCVAb) of students from other regions (1.5%), a significantly high seropositivity for anti-HCVAb was encountered in Egyptian participants (21.1%). In recent years, population shifts and rapid transportation have facilitated the spread of certain infectious diseases from endemic to non-endemic areas. International preventive strategies, education of people regarding infectious diseases, and sufficient medical staffs for this purpose are urgently recommended.

[Remaining solvents in dry cleaned over clothes].

We examined remaining solvents in dry cleaned trousers to estimate the magnitude of environmental pollution. A cleaning solvent of petroleum hydrocarbon was analyzed by means of capillary column mass spectrum gas chromatography. Principal ingredients were identified to be nonane, decane and undecane. The same main components were detected in dry cleaned trousers. Total amounts of evaporated vapor from a pair of trousers (480 g) in 5 days after dry cleaning were nonane (0.73 mg), decane (1.53 mg) and undecane (1.09 mg). The levels on the fifth day were 5%(nonane), 18%(decane) and 32%(undecane) of the first day's concentration, respectively. The half times of the remaining solvents were 1.0 day (nonane), 1.7 days (decane) and 2.7 days (undecane), respectively.

[Examination of dust generated from a workplace where steel wire coil are unwound].

Analyses of constituents, measurement of concentrations, research of size distributions and scanning electron microscopic examinations were carried out to determine the type and amount of dust generated in a working environment where steel wire coils are unwound. In about a 700 m2 work area unit, stationary samplings, including A-sampling (24 points) and B-sampling (1 point), which are defined by the law, were carried out. The dust concentration was measured by a digital dust indicator. A low volume air sampler was used to determine the conversion factor of the values obtained by the digital dust indicator. Because the result of the dust level by A-sampling and B-sampling were 0.64 mg/m3 and 0.82 mg/m3 respectively, they can both be classified as Control Class 1. A proportion of less than 7 microns of the airborne dust made up about 15 to 20% (volume %) of the total dust in the working environments. Metallic dust and white dust were identified in the accumulated dust. By measuring with a X-ray diffractometry, it was determined that the metal dust constituent was Zn and the white dust constituent was Zn4CO3(OH)6.H2O. By a scanning electron microscopic examination, the scope of the particles was proven to be non-fibrous.

[A case of Satoyoshi syndrome with symptoms resembling neuroleptic malignant syndrome].

Satoyoshi syndrome is a rare neurological disorder of unknown etiology characterized by progressive muscle spasms, alopecia, diarrhea and skeletal abnormalities. We here describe a 25-year-old man who developed symptoms similar to neuroleptic malignant syndrome (NMS). He began to have the clinical characteristics of Satoyoshi syndrome at the age of 12 years. He was admitted to hospitals many times with painful muscle spasms and pyrexia in the early stage of the disease. He received steroid pulse therapy and oral prednisone at the age of 19, the extent and frequency of the spells being reduced thereafter. He was admitted to our hospital due to recurrence of his usual muscle spasms. He was treated with midazolam intravenously to relieve severe muscle ache, pain in the left shoulder, and insomnia. About 90 minutes later, he became comatose, with the following manifestations: hyperthermia, low blood pressure, tachycardia, profuse perspiration, acute respiratory failure, and ensuing cardiac arrest. He developed rhabdomyolysis, acute renal failure, hepatic damage, and diffuse intravascular coagulation. Serum creatine kinase level was elevated to 306,910 IU. He died of multiple organ failure 13 days after admission. His symptoms resembled NMS and malignant hyperthermia (MH). None of patients with Satoyoshi syndrome accompanied by NMS or MH have been reported. It remains to be clarified whether midazolam administration induces NMS in Satoyoshi syndrome. Nevertheless, careful attention should be paid when one administers midazolam to patients with this syndrome.

[Research on the contents of material safety data sheets].

The Material Safety Data Sheet (MSDS) system for the safe management of chemical substances was officially promulgated in 1993 and has been gradually put into practice through administrative guidance in Japan. However, little research has been done on the quality of such data sheets provided from various sectors of industries. We examined two sets of MSDSs obtained from a refractory ceramic plant. In the first survey in 1995, the set of MSDSs was from July, 1992 to March, 1994; and in the second survey in 1997, the set was from April, 1994 to November, 1996. The number of MSDSs examined in these two surveys was 159 and 81, respectively. The number of MSDSs in which "Hazard Identification" was indicated was 100 (63%) in the 1995 survey and 75 (93%) in the 1997 survey. The number of those in which "Toxicological Information (Stability and Reactivity)" was indicated was 81 (51%) and 80 (99%), respectively. The description rates for the essential items, including the above two, were found to be improving.

[Carotid blood flow volume measurement using an ultrasonic Doppler flowmeter--predictive diagnosis of ischemic cerebrovascular diseases].

BACKGROUND: It is difficult to predict ischemic cerebrovascular diseases by noninvasive methods before overt symptoms develop. Advanced carotid and cerebral atherosclerosis reduce common carotid blood flow volume due to increased resistance of peripheral circulation. According to a study in which clinical and pathological specimens were compared, the lower threshold for the flow volume in normal individuals has been confirmed to be 6.5 ml/s. We investigated the possibility that the development of ischemic cerebrovascular diseases can be predicted based on blood flow volume. METHOD: We conducted a retrospective study on 314 patients who were available for determination of common carotid blood flow volume with an ultrasonic quantitative flowmeter. RESULTS: Thirty-three patients developed ischemic cerebrovascular attacks during the observation period (onset group), while the remaining 281 did not develop attacks (non-onset group). The discriminating value for common carotid blood flow volume between the onset and non-onset groups was 6.8 ml/s. Based on an odds ratio of 6.7, it was concluded that a common carotid blood flow volume of less than 6.8 ml/s is highly likely to predict the onset of ischemic cerebrovascular accidents.

[Report on occupational health and safety practice, level 4].

Recently, because international standardization systems have been set up in many fields, it is necessary for Japanese companies to employ persons who have specific knowledge and techniques in regards to occupational health and safety. In this paper, therefore, we discuss Occupational Health and Safety Practice, Level 4, and try to compare it with Japanese licences. The standard was developed by the Occupational Health and Safety Lead Body (OHSLB) in England. This standard is intended for occupational health and safety practitioners working in general health and safety. We conclude that the training system for occupational health and safety practitioners in Japan must be developed more fully.

Relationship between ultrasound assessment of arterial wall properties and blood pressure.

Physical properties of an artery can be described in terms of stiffness, distensibility, and compliance. Changes in these properties can predict atherosclerosis disease, but it is necessary to identify an index that is independent of changes in blood pressure. We measured common carotid artery diameter and pulsatile change with an ultrasonic phase-locked, echo-tracking system in 7 subjects whose mean brachial blood pressure had varied 15 mm Hg or more within a month. Patients taking antihypertensive agents were excluded from the study. We measured changes in arterial diameter (n = 41) at least four times during the study period and calculated the pressure-strain elastic modulus (Ep), distensibility coefficient (DC), cross-sectional compliance (CC) and stiffness parameter (beta) from inner diameter, its pulsatile change, and blood pressure. The correlation coefficients of mean blood pressure with each index are as follows: Ep, 0.53; DC, 0.58; CC, 0.63; beta, 0.21. When mean blood pressure increased 1 mm Hg, the change in each index at 100 mm Hg was as follows: Ep, 1.48 +/- 1.30%; DC, -1.05 +/- 0.97%; CC, -0.69 +/- 0.90%; beta, 0.45 +/- 1.11%. Among the four indices that measure the properties of the arterial walls, stiffness parameter beta was the least dependent on blood pressure. Thus, it appears to have usefulness as an index of arterial wall sclerosis.

Acetylpolyamine amidohydrolase from Mycoplana ramosa: gene cloning and characterization of the metal-substituted enzyme.

We have cloned a gene (aphA) encoding acetylpolyamine amidohydrolase from Mycoplana ramosa ATCC 49678, (previously named Mycoplana bullata). A genomic library of M. ramosa was screened with an oligonucleotide probe designed from a N-terminal amino acid sequence of the enzyme purified from M. ramosa. Nucleotide sequence analysis revealed an open reading frame of 1,023 bp which encodes a polypeptide with a molecular mass of 36,337 Da. This is the first report of the structure of acetylpolyamine amidohydrolase. The aphA gene was subcloned under the control of the trc promoter and was expressed in Escherichia coli MM294. The recombinant enzyme was purified, and the enzymatic properties were characterized. Substrate specificities, Km values, and Vmax values were identical to those of the native enzyme purified from M. ramosa. In the analysis of the metal-substituted enzymes, we found that the acid limb of pH rate profiles shifts from 7.2 for the original zinc enzyme to 6.6 for the cobalt enzyme. This change suggests that the zinc atom is essential for the catalytic activity of the enzyme similarly to the zinc atom in carboxypeptidase A.

Alterations of hepatic drug metabolising system due to dimethylformamide (DMF).

The effect of repeated exposures to N, N-dimethylformamide (DMF) on the liver and the hepatic microsomal monooxygenase system and glutathione metabolizing enzymes were investigated. DMF was administered to Wistar male rats by subcutaneous (s.c.) injection at 1.0 ml/kg body weight (950 mg/kg), 3 times a week for 2 weeks. The gain in the body weight in the DMF group were suppressed compared with the control group at 2 week. The relative weight of the liver, spleen and kidney also appeared to increase in the DMF group as same as in the control group. Hematological examinations showed no changes. Glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) did not change in the DMF group. Hepatic microsomal protein and cytochrome P-450 did significantly decrease by 30% and 38%, respectively, while there was no change in cytochrome b5, NADPH-cytochrome c reductase and NADH-ferricyanide reductase. Glutathione peroxidase (GPx) activity was not affected by DMF administration, while glutathione reductase (GR) and glutathione S-transferase, (GST) activity were significantly increased by 16% and 64%, respectively. These results indicate that DMF alters tke hepatic drug metabolizing system without significant increase of the serum transaminase levels. These findings may contribute to elucidate the mechanism of DMF hepatotoxicity.

Common carotid artery wall properties in Takayasu's arteritis.

The vessel wall properties of the common carotid artery have been noninvasively and quantitatively assessed with an ultrasonic instrument. Stiffness parameter beta, which represents the mechanical properties of the vessel, was calculated from the relationship between blood pressure and the diameter of the artery. There are no reports that quantitatively assess wall properties in Takayasu's arteritis. The authors compared, in vivo, the vessel wall properties of the common carotid artery in 14 patients with Takayasu's arteritis versus those in 60 normal subjects (controls). They measured changes in the inner diameter of the artery between systole and diastole with an ultrasonic, phase-locked, echo-tracking system. Beta was significantly higher in Takayasu's arteritis than in normal subjects (better than a 99% confidence interval). The findings for each decade were as follows: 3rd decade (20s): 35.7 +/- 28.9 vs 5.01-6.46, P=0.0001; 4th decade (30s): 19.5 +/- 9.71 vs 6.09-7.80, P=0.02; 5th decade (40s): 26.2 +/- 11.3 vs 7.26-9.28, P = 0.0001; 6th decade (50s): 19.1 +/- 4.27 vs 8.66-11.25, P = 0.0001. Takayasu's arteritis significantly impaired the mechanical performance of the common carotid artery. Thus, beta shows promise as a useful diagnostic indicator of Takayasu's arteritis.

[Application of neurobehavioral tests in a manufacturing automotive parts factory].

Three neurobehavioral tests and a profile of mood states (POMS) test, which are included in the WHO neurobehavioral core test battery, were applied to 106 workers engaged in manufacturing automotive parts, especially for the purpose of determining the presence or absence of a significant difference in the score between a group of sixty-one workers chronically exposed to organic solvents and a group of forty-five workers unexposed. The scores of both pursuit-aiming and digit-symbol substitution tests were lower (P < 0.02 and P < 0.01, respectively, in analysis of covariance) in the group of exposed workers than in the group of unexposed workers. Furthermore, in the group of exposed workers, the pursuit-aiming and digit-symbol substitution scores showed a positive correlation (P < 0.05 and P < 0.01, respectively) to the fatigue score in the POMS test. On the other hand, the score of the digit span test showed no significant difference between the two groups. No significant correlation was found between the urinary hippuric acid level and the score of each of the three neurobehavioral tests. Therefore, among the exposed workers, the perceptual motor function evaluated in pursuit-aiming and digit-symbol tests seems to be affected. The neurobehavioral tests administered in this study are limited in number and in function, however, the comparison of their scores between the exposed and unexposed workers may suggest the presence of adversive effects of chronic exposure to organic solvents.