Biomedical subjects
E Yano
Publications and source records attributed to E Yano.
Cancer mortality among workers exposed to amphibole-free chrysotile asbestos.
The issue of whether exposure to chrysotile asbestos alone, without contamination from amphibole asbestos, causes lung cancer and mesothelioma was investigated in a 25-year longitudinal study (1972-1996) in Chongqin, China. The study cohort comprised 515 male asbestos plant workers exposed to chrysotile only; the control cohort included 650 non-dust-exposed workers. The results of analysis in which the proportional hazards model was used indicated that mortality due to all causes, all cancers, and lung cancer was related to asbestos exposure; the relative risks, adjusted for age and smoking, were 2.9, 4.3, and 6.6, respectively. Fiber concentrations in the raw material section and the textile section of the plant were 7.6 and 4.5 fibers/ml, respectively. Because of differences between the study and control plants, the authors also compared various sections of the asbestos plant that had different levels of dust exposure. The adjusted relative risk of lung cancer was 8.1 for workers exposed to high versus low levels of asbestos. Two cases of malignant mesothelioma, one pleural and the other peritoneal, were found in the asbestos cohort. These results suggest that heavy exposure to pure chrysotile asbestos alone, with negligible amphibole contamination, can cause lung cancer and malignant mesothelioma in exposed workers.
Intervention for prevention of low back pain in Japanese forklift workers.
BACKGROUND: The effectiveness of two different approaches for the prevention of low back pain (LBP) was compared in forklift workers. The first approach (personal) consisted of providing lumbar support, arctic jacket and physical exercise, and the second (facility approach) included the improvement of forklift seats and tires. METHODS: The self-reported prevalence of LBP was surveyed three times before and after the two forms of interventions, in 260 male blue-collar workers including 27 forklift workers, and 55 male white-collar workers of a copper smelter. RESULTS: The initial prevalence of LBP was 63% in the forklift workers, which was significantly higher than that found in the other blue-collar workers (32%) and in the white-collar workers (22%). One year after the first intervention (personal approach) to the forklift workers, the prevalence of LBP fell to 56%. The second intervention (facility approach), which was mainly comprised of a reduction in whole body vibration, was subsequently added, and 9 months later the prevalence of LBP in the forklift workers further decreased to 33%. The reduction of the prevalence from the initial survey was significant (P = 0.008), and that from the second survey was nearly significant (P = 0.070). CONCLUSIONS: These findings suggest that the facility approach is more effective for a reduction of LBP than the personal approach.
Test validity of periodic liver function tests in a population of Japanese male bank employees.
The validity (sensitivity and specificity) of annual liver function tests, determined by assaying blood levels of aspartate aminotransferase, alanine aminotransferase and gammaglutamyl transpeptidase, was evaluated using the results of health checkups of male bank workers. The specificity of each liver function test to detect persons with fatty liver, excess alcohol users, and hepatic virus carriers, diagnosed respectively by ultrasound, detailed inquiry, and virus marker tests, was always higher than 80%, except for alanine aminotransferase in excess alcohol users (63.5%). However, the highest sensitivity to detect virus carriers was alanine aminotransferase to detect HCV antibody-positive workers, but it was only 45.5%. The highest sensitivity of the liver function tests to detect excess alcohol users in obese subjects was only 33.3%. The highest sensitivity by liver function tests to detect fatty liver was 35.7% which was inferior to that of the body mass index. These results indicate that the liver function tests mandated in the workplace periodic health checkups in Japan exhibit very low sensitivity for the detection of any of the proposed target clinical conditions.
Pulmonary function in long-term asbestos workers in China.
The relationship of pulmonary function to exposure to asbestos and radiographic abnormalities has been controversial, especially when smoking is present as a confounder. The aim of the study was to provide further understanding on the radiographic-physiologic associations in nonsmoking and smoking asbestos workers. Radiographic asbestosis, pleural lesion, and pulmonary function were studied in 269 Chinese asbestos workers, with average exposure years of 23 for male workers and 18 for female workers. Their functional data were compared with those of 274 controls without exposure to dust. Although most of the male workers were smokers, none of the female workers smoked. In comparison with controls, asbestos workers had significantly lower lung volume and diffusing capacity, irrespective of gender. Female workers and smoking male workers had lower measurements of forced expiratory volume in 1 second and instantaneous forced expiratory flow at 50% and 25% of forced vital capacity. After adjustment for relevant covariates, asbestos exposure, asbestosis, and pleural abnormalities were associated with decreased parameters of pulmonary function, including lung volume, diffusing capacity, and airway flow. These data indicate that asbestos-related functional defects manifested by lung restriction and mild airway obstruction correlate with exposure to asbestos and with parenchymal and pleural abnormalities, independent of smoking.
Blood lead levels in copper smelter workers in Japan.
Lead exposure of workers in a Japanese copper smelter was assessed by determining lead levels in blood, air and flue cinder at the copper smelting processes. All the samples were analyzed for lead by atomic absorption spectrometry. Mean lead levels of air were highest at the anode department followed by the converter, smelter and blend departments. The mean level of blood lead of the workers in the anode department was also the highest among the four smelting departments. The mean blood lead levels of the workers in each department were positively correlated with their air lead levels (r = 0.99, p < 0.01). This study indicates therefore that workers in copper smelters have been exposed to lead in their workplace. Though this finding has already been reported in preceding studies, the Ordinance on Prevention of Lead Poisoning in Japan has not included copper smelter into its target job categories if their lead concentration in the raw material is less than 3%. The limitation of the present Ordinance which defines the targets by the types of job and not by the actual exposure, is discussed.
[A comparison between three methods to investigate falls among the elderly living in the community].
PURPOSE: Interview survey is the often selected method to investigate falls among the elderly. However, the reliability of data obtained by that method has not be confirmed. The aim of this study is to clarify the number of intervals of recollection that should be specified to ensure accurate data when we investigate falls by using interview surveys among the elderly. METHODS: We carried out a total health survey among the elderly in Shigenobu town, and reported about the frequency of falls and its relating factors. Sex, age, walking ability over a distance of 1 km and hospitalization experience for past 1 year were related to falls significantly. In this study, we set 3 groups matching for the above factors in addition to history of falls during the preceding a year, and for one year we asked about falls every month for the first group (116 participants), every 3 months for the second group (116 participants) respectively. The third group (118 participants) was asked once at the end of this study. These three groups totaled 350 persons who were participants of physical fitness measurements that we carried out in Shigenobu town. The existence of falls was investigated by mail, and the nonrespondents were questioned by direct telephone calls. RESULTS: For reasons such as death, moving out, hospitalization and answer denial, persons whose answer was not obtained were excluded from the analysis. Finally, 87.1% in the 1st group, and 89.7% in the 2nd group and 96.6% in the 3rd group were analyzed. Statistically significant difference for the above factors related to falls did not exist among the 3 groups. Annual incidence for falls tended to be more frequent in the 1st group that in the 3rd group (20.5% in the 1st group, 15.9% in the 2nd group and 6.4% in the 3rd group) in males. In females, such a difference was not observed. (26.3% in the 1st group, 18.3% in the 2nd group and 20.9% in the 3rd group). CONCLUSIONS: There were no significant differences for the factors related to falls in 3 groups, therefore, the groups had almost similar backgrounds. In men, the difference of annual reported incidence between the 1st group and the 3rd group may be due to differences in the method of recollection.
Respiratory symptoms and pulmonary function in coal miners: looking into the effects of simple pneumoconiosis.
BACKGROUND: Although severe impairment of pulmonary function is believed to occur commonly in complicated pneumoconiosis, the relationships of simple coal workers' pneumoconiosis (CWP) to pulmonary function and respiratory symptoms have remained under debate. The study aims to investigate if simple pneumoconiosis is associated with significant impairment of pulmonary function and increased risk of respiratory symptoms. METHODS: Spirometry and diffusing capacity were performed in 205 miners with simple CWP and 289 without X ray evidence of pneumoconiosis, who were selected from a large underground coal mine in China. A questionnaire on occupational history and respiratory symptoms including breathlessness, chronic cough, and phlegm was administered. The presence or absence of emphysema on their X-ray films was also evaluated. Logistic regression and multiple linear regression analysis were applied to estimate the independent effect of CWP on respiratory symptoms and parameters of pulmonary function. RESULTS: On the average, the miners with CWP had lower values of pulmonary function and higher prevalences of respiratory symptoms, and emphysema than did those without. The simple CWP was associated with increased risk of the respiratory symptoms after adjusting for age, smoking, and years underground. Regression analysis showed that the CWP had significantly independent effects on parameters of pulmonary function. Even when the effects of emphysema, respiratory symptoms indicating chronic bronchitis were taken into consideration, the significant relationship between CWP and decrements in FVC and diffusing capacity remained. CONCLUSION: The findings of this study are consistent with simple CWP being a contributor to significant decrements in pulmonary function, and to increased risk of respiratory symptoms.
Pulmonary dysfunction in silica-exposed workers: a relationship to radiographic signs of silicosis and emphysema.
BACKGROUND: It has been established that occupational exposure to silica dust may cause significant impairment of pulmonary function. To compare the contribution of silicosis and emphysema to pulmonary dysfunction, radiographic signs of silicosis and emphysema in silica exposed workers were analyzed. METHODS: Two hundred and twenty workers exposed to silica working in a Chinese refractory plant were selected as study subjects. Their findings of silicosis and emphysematous changes on radiograph were classified and evaluated. A questionnaire on respiratory symptoms, smoking, and occupational history was administered. All the workers performed measurements of spirometry and CO single-breath diffusing capacity. RESULTS: Radiographic hyperinflation was detected in 9% of the workers without silicosis and in 33% of the workers with silicosis. Silicosis was significantly associated with hyperinflation after adjusting for exposure duration, age, and smoking. Respiratory symptoms were more frequent in the more severe cases of silicosis. Regression analysis showed that silicosis was significantly associated with decreases in the parameters of pulmonary function, but the significance disappeared when the hyperinflation term was added to the models. Radiographic hyperinflation was strongly associated with decreases in FEV1 and FEV1/FVC while relevant factors were controlled. Comparison between workers with and without hyperinflation showed that the former had significantly lower pulmonary function values. CONCLUSIONS: The results suggest that emphysema associated with silicosis is likely to be responsible for pulmonary obstruction and decreased diffusing capacity occurring in silica-exposed workers.
Selection effects on an estimation of long-term changes in pulmonary function.
To reveal the association of initial pulmonary function level with subsequent mortality and participation in a follow-up reexamination, a prospective cohort study was performed. Female residents in a volcanic area of southern Kyushu, Japan, were followed up for their vital status and the pulmonary function 15 years after they received the first pulmonary function test. A cohort of 512 Japanese female residents who were examined for pulmonary function as indicated by forced expiratory volume and forced expiratory volume in one second was measured in a baseline examination in 1980. After 15 years, 35 females were lost to follow-up. Of the remaining 477 females, 340 and 137 females provided good and poor levels of pulmonary function tests (PFT) at baseline, respectively. Mortality by 1995 in the poor PFT group was significantly higher than that in the good PFT group (33.6% vs 9.4%). The mortality differences were still highly significant when the 35 lost cases were included as all alive. Among the 399 survivors, the nonparticipation rate in the reexamination in 1995 was significantly higher in the poor PFT group than that in the good PFT group (80.2% vs 69.5%). The results of the present study, a longitudinal study of pulmonary function, provide evidence of selection effects due to death or failure to participate in a subsequent reexamination.
Cardiovascular dysfunction due to shift work.
Electrocardiographic, biochemical, and physical data obtained from 237 shift and 115 day workers without any obvious disorders were assessed to clarify the impact of shift work on cardiovascular functions. The heart-rate corrected QT interval (QTc) was significantly longer in the shift workers than in the day workers. However, blood pressure, working duration, and biochemical and other data were comparable between the two work groups. When multiple regression analysis was used, shift/day work was significantly related to the QTc in all of the workers. The adjusted odds ratio of shift work to the prolonged QTc (> or = 440 ms1/2) was 8.15. The prolonged QTc has been thought to contribute to an increased risk of cardiac death. These findings, therefore, suggest that the increased risk for cardiovascular mortality in shift workers may be attributable to prolongation of the QTc.
Impact of shift work on cardiovascular functions in a 10-year follow-up study.
OBJECTIVES: The purpose of this study was to determine whether shift work affects the heart-rate-adjusted QT interval (QTc) in electorcardiography (ECG) and the blood pressure of workers without overt cardiovascular dysfunction. METHODS: At a copper smelter, 158 shift workers and 75 day workers who underwent an ECG examination and blood pressure measurements in 1986 were followed for 10 years. In 1996, biochemical indicators such as high-density lipoprotein cholesterol and triglycerides were measured, together with the QTc. RESULTS: In 1986 and 1996, the QTc was significantly longer in the shift workers than in the day workers. Of 180 workers with a normal QTc (<420 ms(1/2) in 1986, 15% had developed a prolonged QTc (420 ms(1/2) in 1996 (18% of the 117 shift workers and 11% of the 63 day workers). Among the workers with a normal QTc in 1986, the shift workers had a significantly longer QTc than the day workers when the QTc was examined in 1996. In addition, shift-day work in the group with a normal QTc was significantly related to the QTc in 1996 after control for age, work duration, biochemical indicators, smoking, and drinking habits. However, the blood pressures of the shift and day workers did not differ significantly, and in 1996 the values of both groups were significantly elevated. CONCLUSIONS: These data suggest that shift work is associated with QTc prolongation. This evidence may explain the increased risk for cardiovascular diseases due to shift work.
[Teaching hygiene and public health with student facilitators an attempt to enhance student participation].
In order to enhance student participation in lectures of hygiene and public health, we introduced a student facilitator (SF) system into the lectures of the fourth grade medical students. All students were assigned to one of the 28 classes as SF, thus each class had 4 to 5 SFs. A few weeks before the lecture, each teacher gave SFs various instructions to prepare for the class depending on the theme and teaching strategies. Some classes consisted of dialogues between the teacher and SFs in other classes gave presentations related to the theme of the lecture. For example, SFs in a class of epidemiology performed a small epidemiological survey using their fellow students as study subjects, thus allowing students to learn epidemiological design and calculation of odds ratios. In a class of care management, SFs played roles of caregiver, family member, social worker, physician, etc., showing how actual care management is conducted. The evaluation survey for the SF system showed that in general, students rated the SF system positively, especially at the time they served as SFs. Most of the students showed more interest in the subjects and felt more confident about what they learned as compared to ordinary classes. This finding is important because, previously, the largest problem with the lectures of hygiene and public health used to be the poor interest of students in the subject itself. On the other hand, students sometimes complained about the poor quality of the presentation by SFs. Also, a few students sometimes felt that for obtaining the large volume of knowledge required by the national board examination for medical practice, the SF system was inefficient. In summary, the SF system has some advantage in evoking interests in learning hygiene and public health with sufficient systematic preparation. However, it may not be an efficient way to simply obtain large amounts of knowledge. To improve the SF system, well designed teaching strategies in addition to a carefully prepared textbook are essential.
[Validity of urinary glucose test for diabetes screening in workplace regular medical checkups].
It has been acknowledged that urinary glucose level varies depending on the time after meal which may hence affect validity of urinary glucose test as a screening test for diabetes. However, sample collection time has not been standardized for urinary glucose test in workplace regular medical checkups. In this study, we investigated the effect of timing of urine sampling on results of urinary glucose screening tests, and using data obtained from the 75 g oral glucose tolerance tests (OGTT) evaluated the validity of urinary glucose test in workplace medical checkups. Also, we made a survey among industrial physicians about the timing of sample collection. Between 1991 and 1996, 455 males and 116 females who participated in a 2-day health examination including the OGTT in a hospital in Chiba were used as study subjects. These did not include an additional 22 subjects who had already been diagnosed as having diabetes but received the OGTT. The examinees observed a strict fast after supper the previous evening and urine and blood samples were collected before and 2 hours after glucose intake for the OGTT. Diagnosis of diabetes was made following the criteria of WHO (1985) and screening test results were defined positive when urinary glucose level was equal to or more than 40 mg/dl. Sensitivity and specificity were calculated for diabetes and impaired glucose tolerance separately for male and female. Industrial physicians who participated in a lecture course for qualification were surveyed about the timing of urine sample collection for urinary glucose test in workplace regular medical checkups. For the urine samples collected 2 hours after glucose intake, sensitivity was very high (male 84%, female 100%), in addition to a relatively high specificity (male 71%, female 92%). However the samples collected before glucose intake showed extremely poor sensitivity (male 11%, female 0%). Similar results were obtained when screening was made for impaired glucose tolerance and both diabetes and impaired glucose tolerance combined. The survey among the industrial physician revealed that in the majority (58%) of workplace medical checkups, the urine sample had been collected when examinees were fasting. The largest reason for this was that the urinary glucose test was performed together with upper gastro-intestinal examination or measurement of serum triglyceride both of which require fasting of examinees. The results of the present study showed that urinary glucose tests have been frequently performed at a timing that produces low validity. The procedures of workplace regular medical checkups should be evaluated with the concept of Evidence Based Medicine. The standard of the timing of urine sample collection for urinary glucose test should be carefully examined.
Ankle-arm index as an indicator of atherosclerosis: its application as a screening method.
The ankle-arm blood pressure index (AAI) is seldom used to screen for atherosclerotic diseases other than lower extremity arterial disease. This study was conducted to investigate whether the AAI can be used as a screening test for atherosclerotic diseases in general. The subjects were 446 male workers in a copper smelter. Fundoscopic examinations, electrocardiograms, serum cholesterol and triglyceride measurements, and AAI measurements were conducted. Information on past medical histories of diabetes mellitus and ischemic heart disease, smoking, alcohol intake, duration of sleep and physical activity were collected. The AAI correlated well with the results of the fundoscopic examinations, and an AAI of 1.00 gave the maximum sensitivity specificity product. The same AAI value also gave the maximum products for ST segment depression in electrocardiograms and the past history of ischemic heart disease. Multiple logistic regression analysis showed that a low AAI value was related to higher systolic blood pressure and current smoking but was inversely related to alcohol intake. Our study validated the AAI in predicting persons with risk factors of atherosclerotic diseases. The AAI measurements can be conducted at low cost, using simple techniques, and are noninvasive. We propose that the AAI be widely used to screen for atherosclerotic diseases.
Correlation between UVB irradiation and the proportion of cataract--an epidemiological study based on a nationwide patient survey in Japan.
Among the multiple factors affecting the human eye in work environment, ultraviolet B irradiation (UVB) has received much attention recently. To provide a clear information for the association between cataract and UVB irradiation, the prevalence data from the Patient Survey and UVB estimates in all the 47 prefectures in Japan were used to examine the relationship between cataract and UVB. In analyzing the relationship, we controlled possible effect modifiers; which were aged, that is 65 years old (yo.) or older, population per ophthalmologist, proportions of all the patients among the aged population and proportion of very elderly population (75 yo. or older) among the aged population. A sex-specific logistic regression analysis revealed that the adjusted odds ratio in women was 1.118 with a 95% confidence interval of 1.058-1.183. However, the adjusted odds ratio in men was not statistically significant (1.048 with 95% confidence interval 0.968-1.135). The unstable results of this study may be largely due to the non-definitive estimation of UVB exposure that this kind of study should be repeated when more valid UVB estimates is available.
[Simulation exercises, a problem oriented method of learning public health in medical education].
Using the case method of learning of American business schools, we introduced "Simulation Exercises (SE)," a problem oriented method of public health education for medical students. With SE, a group of students were given simulated cases of patients or situations (SC), and were asked to assume the role of physicians or other public health workers using their skills and knowledge of public health. Students learn on their own, with the aid of tutors, through discussion, role-play, investigation of literature, and a small field survey. There have been a whole variety of SC covering most of the current topics in public health ranging from mental health, dental health, industrial health, maternal & child health, elderly care, terminal care and international health. Each SC has 5 to 10 questions which stimulate and direct the students' group discussion. Some of the questions do not have a correct answer, but the criteria used to evaluate the students included clarity, consistency, and comprehensiveness of their ideas in addition to the positive commitment to the group discussion. At the end of the week-long group learning, each group demonstrated the results of their discussion. Role play was often used to demonstrate what they learned. As a result, students participated positively and concentrated and enjoyed the learning exercise very much. An anonymous survey shortly after SE showed that more than 80% of students felt a positive change in their rating of public health among the many subjects of study. Tutors also changed their rating of the students after observing their positive attitude and sometimes very creative ideas. In conclusion, we found SE to be useful for practical learning by medical students of public health.