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Biomedical subjects

Yukinori Kusaka

Publications and source records attributed to Yukinori Kusaka.

16 recordsLinked to original sources

Historical and geographical aspects of the increasing perfluorooctanoate and perfluorooctane sulfonate contamination in human serum in Japan.

Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) have recently received attention due to their widespread contamination in the environment, as well as in wildlife and humans. We measured the PFOS and PFOA concentrations in historically recorded human serum samples at an age range between 20 and 59 years collected in Kyoto, 20 persons per each time point (n=100), and also the PFOS and PFOA concentrations in human serum samples at an age range between 20 and 59 years from 10 locations throughout Japan (n=200). The historical samples collected from 1983 to 1999 demonstrated that the PFOA concentrations in males and females from Kyoto have increased 4.4-fold and 4.3-fold at a rate of increase of 0.49 ng/ml/year and 0.42 ng/ml/year, respectively. In contrast, serum concentrations of PFOS reached a plateau in the late 1980s. There are also regional differences in both the PFOS and PFOA serum concentrations. The concentrations in serum [geometric mean (geometric standard deviation)] (ng/ml) in 2003-2004 ranged from 7.6(1.6) in the town of Matsuoka in Fukui prefecture to 27.8(1.6) in Kyoto city, and ranged from 2.3(1.5) in Matsuoka to 14.5(1.3) in Osaka city for PFOS and PFOA, respectively.

Adult↗

Selection of reference films based on reliability assessment of a classification of high-resolution computed tomography for pneumoconioses.

OBJECTIVE: Worldwide demand has increased for the development of a computed tomography (CT) classification system that supplements the ILO classification of radiographs for pneumoconioses. The authors aimed to show preliminary reliability test results for selected referent films for the CT classification system developed through an international effort by researchers from seven countries. METHODS: Reading trials by eight physicians who have considerable experience in pneumoconioses using a total of 114 lung zones consisting of 6 lung zones of 19 CT films of dust-exposed workers were performed to assess reliability of the classification system by weighted kappa. The results were also utilized for selecting reference films. RESULTS: A good agreement was observed for both first and second reading trials for rounded opacities (weighted kappa=0.76, 0.74, first and second trial results, respectively), irregular opacities (0.60, 0.48), emphysema (0.56, 0.70) and honeycombing (0.72, 0.79). Ground glass opacities, on the other hand, showed moderate agreement (0.43, 0.38). Intra-reader agreements among eight readers were shown in the same table as the mean and standard deviation of weighted kappa statistics. The inter-reader agreement for pleural thickening was not as good as for parenchymal lesions. DISCUSSION: The CT classification development may pioneer noble and sensitive medical screening for dust-exposed workers in selected settings. This system may be applied to radiographic borderline cases of profusion 0/1 and 1/0 by the ILO classification, in a setting that assures the occupational safety and health of workers exposed to some newly developed chemical compounds.

Classification↗

Trunk muscle strength is a strong predictor of bone loss in postmenopausal women.

UNLABELLED: To clarify whether trunk muscle strength and self-reported exercise habits predict subsequent bone loss in healthy post- menopausal women, we examined 143 community-dwelling ambulatory postmenopausal Japanese women (age: 59.9 +/- 6.5 years) without any diseases affecting bone metabolism at baseline, and followed 109 of the 143 subjects for 4 years. Bone mineral density at baseline and at followup was measured at the spine by DEXA to determine the annual change in bone mineral density during the followup. Subjects who lost bone mineral density at an annual rate exceeding -1.78% (1 standard deviation below the mean rate) were defined as rapid bone losers. The isokinetic concentric and eccentric peak torques of the trunk flexors and extensors were measured at baseline. The exercise habits of the subjects were evaluated through detailed interviews. The eccentric trunk flexor and extensor torques were found to correlate with a positive dose-dependent effect on change in bone mineral density while exercise habits showed no correlation. The lower tertile group for the extensor torque showed a ten-fold greater risk for rapid bone loss compared with the upper tertile group. Postmenopausal women with decreased trunk muscle torque may be at increased risk for osteoporosis and should be a target group for preventive measures. LEVEL OF EVIDENCE: Prognostic study, level II (prospective study). See the Guidelines for Authors for a complete description of the levels of evidence.

Absorptiometry, Photon↗

Physical work load affects the maximum oxygen uptake.

PURPOSE: Maximum oxygen uptake (VO2max) is known to be influenced by life-style factors, such as exercise and smoking. We aimed to further test the hypothesis that, besides these, work form also contributes to increase VO2max among workers. METHOD: Three thousand six hundred and forty eight male workers with age 38.3 +/- 12.1 and 1,575 female workers with age 35.6 +/- 11.1, ranging from 20-year old to 69-year old, who participated in Total Health Promotion Plan at workplaces in Fukui Prefecture in 1998 were selected. Data on VO2max were analyzed for age, systolic blood pressure (SBP), body mass index (BMI), work form (sedentary, standing or ambulatory), exercise, and smoking. RESULTS: Multiple regression analysis showed that work form ("standing", "ambulatory"), and exercise habits might increase VO2max while BMI, age, and SBP might decrease VO2max in male participants. Exercise habits were suggested to increase VO2max while BMI, SBP, and age might decrease VO2max in females. In females smoking, was suggested to increase VO2max. CONCLUSION: After adjusting for age, BMI, SBP, exercise, and smoking, it was suggested that the physical work load, represented by the work form, may contribute to increases in VO2max in males. Implications of smoking among females with respect to VO2max is discussed.

Adult↗

[An evaluation of teaching objectives for seminars and clerkship of social medicine in medical schools in Japan].

OBJECTIVES: The purpose of this study was to evaluate the curriculum of seminars and clerkship for social medicine in medical schools in Japan, with special reference to teaching objectives. METHODS: A survey was conducted in December, 2002 by sending questionnaires to all the member departments of the Conference for Hygiene and Public Health Teaching in Medical Schools in Japan. Teaching objectives for seminars and clerkship of social medicine stated in their curricula were analyzed by frequencies of key words related to learner's "Knowledge, Attitude, and Behavior". Also, five professors of public health independently rated the stated teaching objectives using nine evaluation criteria divided into three levels and mean ratings were obtained. RESULTS: Although 80% of the schools described their General Instructional Objectives (GIOs), only 63% of the universities stated Specific Behavioral Objectives (SBOs). Evaluation of the contents of the descriptions revealed that, although many courses described the GIOs with the student as subjective, only a small number of courses mentioned "Attitude and Behavior" in SBO. Also, many courses did not make any apparent distinction between GIOs and SBOs. CONCLUSIONS: Practical training is a crucial component in medical education and seminars and clerkship play an important role in teaching social medicine to medical students. However, the present study revealed that many medical schools in Japan do not have adequately defined teaching objectives. Improvement of the curricula in courses of social medicine is required with particular reference to specific behavioral objectives and goals for seminars and clerkship.

Clinical Clerkship↗

Large-scale evaluation of the current level of polybrominated diphenyl ethers (PBDEs) in breast milk from 13 regions of Japan.

Polybrominated diphenyl ethers (PBDEs) were measured in 2004 in 105 breast milk samples collected from 13 regions of Japan (Hokkaido, Akita, Miyagi, Tokyo, Gifu, Fukui, Kyoto, Hyogo, Wakayama, Shimane, Yamaguchi, Kochi and Okinawa). Six congeners (BDE-28, BDE-47, BDE-99, BDE-100, BDE-153 and BDE-154) were determined by gas chromatography /mass spectrometry (GC/MS). Total PBDE levels ranged from 0.01 to 23.0 ng/g lipid (geometric mean (GM), 1.34 ng/g lipid). BDE-47 (GM, 0.66 ng/g lipid, 59% of sigmaPBDE) was the most abundant congener present in breast milk and was detected in 99% of the samples. Total PBDE levels were higher in northern Japan than in other regions. We analyzed the effects of occupation, age, smoking status, alcohol consumption and number of deliveries on total PBDE levels. None of these factors were significantly associated with the level of PBDEs. The present study revealed that the current level of exposure to PBDEs in Japan is lower than that in the USA or Sweden. GMs (ng/g lipid) (GSD, geometric standard deviation) and medians (ng/g lipid) of PBDE levels in each district are as follows: Hokkaido 2.70 (1.70), 2.74; Akita 4.49 (2.19), 5.44; Miyagi 1.77 (4.37), 1.11; Tokyo 1.39 (2.09), 1.63, Gifu 2.83 (4.79), 2.23; Fukui 1.05 (2.34), 1.18; Kyoto 1.31 (2.95), 1.33; Hyogo 1.02 (2.69), 0.88; Wakayama 1.33 (3.80), 1.70; Shimane 0.83 (2.51), 0.66; Yamaguchi 1.74 (2.82), 1.76; Kochi 0.50 (2.69), 0.74 and Okinawa 1.91 (2.75), 1.22. This is the first large-scale study of current PBDE levels in breast milk in Japan.

Environmental Exposure↗

Assessment of human exposure to polychlorinated biphenyls and polybrominated diphenyl ethers in Japan using archived samples from the early 1980s and mid-1990s.

Persistent organic pollutants have been linked to various adverse effects on human health. We conducted a retrospective exposure assessment for 11polychlorinated biphenyl (PCB) congeners and 4 polybrominated diphenyl ether (PBDE) congeners. We analyzed paired samples of blood and food duplicate portions collected in the 1980s (1980 survey, N=40) and the mid-1990s (1995 survey, N=40) from females (five participants from each of eight sites per survey) living throughout Japan, from Hokkaido to Okinawa. The study populations in the 1980 and 1995 surveys were different but had lived in the same community. We measured PCBs and PBDEs in serum and PCBs in diet. Total serum PCBs (ng/g lipid) [geometric mean (geometric standard deviation)] were similar in the 1980 [163.0 (1.7)] and the 1995 [142.6 (2.0)] surveys. In contrast, dietary intake (ng/day) between 1980 and 1995 decreased significantly, from 522.8 (2.5) to 165.9 (3.3), respectively, (P<0.05). We classified the participants by birth year-before 1941 (older generation) and equal to or after 1941 (younger generation). Serum PCB levels decreased significantly in the younger generation, from 179.1 (1.8) in the 1980 survey to 115.4 (2.0) in the 1995 survey (P<0.05). However, in the older generation, serum levels (ng/g lipid) did not change: 150.4 (1.6) in the 1980 survey and 180 (1.8) in the 1995 survey. Total PBDE serum levels (ng/g lipid) increased significantly during the 15 years, from 0.5 (3.5) to 1.8 (3.7) (P<0.05). At the Shimane site, PBDE serum levels (ng/g lipid) increased 20-fold, from 1.3 (4.8) to 26.0 (5.0). The serum levels of PCBs decreased in the younger generation but not in the older, although levels in daily intakes decreased significantly. Exposure levels of PBDEs appear to be increasing in an area-specific manner.

Adult↗

Secular trends and geographical variations in the dietary intake of polybrominated diphenyl ethers (PBDEs) using archived samples from the early 1980s and mid 1990s in Japan.

A retrospective exposure assessment among the general population for polybrominated diphenyl ethers (PBDEs) was conducted using dietary surveys. We analyzed samples of food duplicate portions collected in the early 1980s (1980 survey: N=40) and the mid 1990s (1995 survey: N=39) from female subjects (5 participants from each of 8 sites per survey except for one site) living throughout Japan, from the north (Hokkaido) to the south (Okinawa). The study populations in the 1980 and 1995 surveys were different, but lived in the same communities. We measured four PBDE congeners [2,2',4,4'-tetrabrominated diphenyl ether (tetraBDE): #47; 2,2',4,4',5-pentaBDE: #99; 2,2',4,4',6-pentaBDE: #100; and 2,2',4,4',5,5'-hexaBDE: #153] in the diet. #99 was the most abundant congener in the diet (49% of the total PBDEs), followed by #47 (33%), #100 (12%) and #153 (6%). Regional variations found in the 1980 survey decreased in the 1995 survey. The total daily intake of PBDEs (ng/d) [GM (GSD)] in the 1980 survey [91.4 (4.1)] was not significantly different from that in the 1995 survey [93.8 (3.4)] for the total population, nor did it differ among the sites including Shimane, in which a 20-fold increase in serum concentrations was observed in the same population1). In consideration of the significant increases in the serum concentration, inhalation may be more important than food ingestion as the route of human exposure to PBDEs.

Adult↗

Development of a food-frequency questionnaire to measure the dietary calcium intake of adult Japanese women.

Assessing calcium intake is necessary for epidemiological studies on osteoporosis. This study was aimed at developing a valid food frequency questionnaire (FFQ) to estimate the dietary calcium intake of Japanese people. The FFQ contains 26 items, representing common sources of calcium. The respondents, 74 women aged 15 - 79 years living in Fukui city, whose dietary calcium intake was estimated at 638 +/- 306 (S.D.) mg based on a one-day weighted food record kept during the National Nutrition Survey of 1996, were asked to indicate their consumption frequency and usual portion size (large, medium, small) for each food item. Trained dieticians interviewed the subjects to confirm their answers to the FFQs. The mean calcium intake per day according to the FFQ (655 +/- 222 mg) did not differ significantly from that according to the one-day food record. The coefficient of correlation between these methods was 0.512, a statistically significant value. The calcium intake from dairy products showed a good correlation, r = 0.717. The coefficient of correlation between the values estimated based on two FFQ filled out three days apart was 0.900, showing good test-retest reliability. Therefore, this FFQ is valid and reliable in estimating dietary calcium intake for epidemiological studies.

Adolescent↗

Direct effect of CoC12 and NiCl2 on citrate uptake by the rat renal brush border membrane.

Co and Ni are essential but relatively rare elements as to organisms. In the mammalian membrane, these metals are transported by the same carrier proteins. The aim of this study was to investigate the direct effects of CoCl2 and NiCl2 on citrate uptake by rat renal brush border membrane vesicles (BBMV). BBMV were prepared by the divalent cation precipitation methods, and citrate uptake was measured by the Millipore rapid membrane filtration technique. The time course of citrate uptake during 120-min of incubation with 1 mM CoCl2 and NiCl2 showed a rapid significant inhibition at the early phase and a slight recover at the late phase. Incubation for 1 min of BBMV with 1, 5 and 25 mM CoCl2 and NiCl2, respectively, significantly inhibited citrate uptake in a concentration-dependent manner compared with that of 0 mM. We discuss these findings from the point of view that Co and Ni are located in Group VIII of the periodic table.

Animals↗

[Mortality, causes and places of death among the elderly with dementia in a community: results of a ten-year follow-up study].

OBJECTIVES: The study was conducted to analyze risk, causes and places of death, and related factors among elderly with and without dementia in a community. METHODS: In 1994, the entire elderly population, aged 65 and older in city K were surveyed for their health status. Among them, 201 were diagnosed as suffering from dementia by psychiatric doctors, according to DSM-III-R. Date, causes and places of death were surveyed individually using the vital statistics record of the national government, for ten years from July 1, 1994. The risk of death adjusted for age-classes, was analyzed with the Cox proportional hazard model. Median survival time was calculated using the Kaplan-Maier method, and causes and places of death were analyzed with the chi2 test. Ten factors at the baseline study were examined for each sex, to analyze their relations to death. RESULTS: Among 198 elderly with dementia followed, 170 died (85.9%), while 1696 (33.9%) died in the 5004 non-dementia group. The hazard ratio for dementia/non-dementia was 2.99, and the female/male was 0.56, stratified by age-classes. The rate for death due to CVD in the elderly with dementia was particularly high accounting for 37.1% of the total. With the CVD and undifferentiated types of dementia, the rate was 47.0%. The rate for malignant tumor was low. In the dementia group, mortality at nursing homes was higher and at hospitals/clinics was lower, compared to non-dementia group (p< 0.05). When stratified by age-classes, the factors significantly related to death of the elderly with dementia were severity of dementia (male), type of dementia (female), being bed-ridden and having impaired walking or toileting capabilities (both sexes). CONCLUSIONS: Dementia is a significant death related factor for elderly people, particularly linked to mortality from cerebro-vascular disease. The type and severity of dementia, and walking or toileting activities appear significant to be factors for death of elderly with dementia.

Aged↗

Occupational allergy in medical doctors.

Allergic diseases have increased in many developed countries including Japan. Doctors are also at risk for allergic diseases from exposure to allergens in working conditions and hospital environments. We investigated the factors relating to occupational allergy in doctors. Self-administered questionnaires were mailed to all doctors (n=895) who had previously graduated from School of Medicine, Fukui Medical University. Data from 307 responders (response rate: 34.3%, male 241, female 66, mean age +/- S.D., 30.8 +/- 4.2) were analyzed. Eighty-nine doctors stated that they had occupational allergy including contact dermatitis, allergic rhinitis and/or asthma. Fifty-four had contact dermatitis caused by surgical gloves; 77 had contact dermatitis from disinfectants, e.g. 23 from chlorhexidine gluconate; 21 from povidone iodine; and 15 from ethanol. Fifteen doctors experienced allergic rhinitis and/or asthma caused by handling laboratory animals. Univariate analysis showed that profession (surgical doctors) and past histories of allergic diseases (rhinitis, sinusitis, or atopic dermatitis) were significantly related to occupational allergy in doctors, but that gender, smoking or physical exercise were not significantly related to it. A logistic regression analysis showed that past histories of allergic diseases and the profession of surgical doctors were significantly related to occupational allergy, but that gender, age or smoking were not significantly related to it. The results of the present study suggest that past history of allergic diseases is a factor predisposing to occupational allergy in doctors. It is necessary and possible to extend more prophylactic measures for doctors, especially for surgeons, because exposure to responsible agents and materials for them can be more frequent.

Adult↗

Assessment of exposure to magnetic fields in occupational settings.

OBJECTIVE: It is important to have data about occupational magnetic field intensity to consider the contribution of occupational magnetic field exposure on the human body. We conducted research on exposure to occupational magnetic fields and tried to qualify data on the distribution of magnetic field' intensity in certain general working environments with individual measurements. SUBJECTS AND METHODS: We performed sample research on the exposure to low-frequency magnetic fields of workers in certain occupations and in the working environment. We also assessed the relationship between working environmental magnetic field distribution and individual exposure. RESULTS: Some occupations were found to be exposed to high magnetic fields. We observed that some workspaces, such as the transformer substation, generally had a uniform and high magnetic field measurement but employees were exposed to a lower intensity. We also found that welders were exposed to high magnetic fields at about 600 microT in a very short time but with a geometrical value of 0.08 microT. CONCLUSION: The determination of administrative levels and control levels, not only of the time weighted average of threshold limits or short term exposure limits, but also ceiling limits should be considered. More systematic research is necessary to determine variables such as operating conditions, measuring position, and frequency bands. Also, further studies will be needed to make a job-exposure matrix for the magnetic fields for each occupation type and to combine it with exposure in non-occupational settings such as commuting and ordinary life situations to explore the causal relationship between exposure to magnetic fields and disease.

Electromagnetic Fields↗

Estimation of trunk muscle parameters for a biomechanical model by age, height and weight.

To establish more accurate equations for estimating the moment arm length and cross-sectional area of the erector spinae and rectus abdominis muscles, the effects of height, weight and age on those muscles were analyzed by using a high-order polynomial equation. Data on the moment arm length and cross-sectional area at L3/4 were obtained from MRI images of 152 males and 98 females. The statistical model used in this study has any combination of up to third-order independent variables for age, height and weight. The effective independent variables were selected by the forward step method of multiple regression analyses. The results of multiple regression analyses showed that the polynomial equations for the moment arm length of erector spinae in both genders, and that for the rectus abdominis in males, contained all three variables of age, height and weight. That for the moment arm length of female rectus abdominis contained the variables of weight and age. The multiple correlation coefficients of the erector spinae and rectus abdominis were 0.355 and 0.650 for males, 0.364 and 0.411 for females, respectively. The equations for the cross-sectional area of the erector spinae in both genders, as well as that for male rectus abdominis contained only one variable (weight). The multiple correlation coefficients of the cross-sectional area of the erector spinae were 0.576 for males and 0.469 for females. The cross-sectional area of the female rectus abdominis had no effective variables.

Abdominal Muscles↗

Comparative toxicity of standard nickel and ultrafine nickel in lung after intratracheal instillation.

A comparison was made of the bronchoalveolar lavage fluid (BALF) response to ultrafine nickel (Uf-Ni) and standard-sized nickel (Std-Ni). Rats were intratracheally instilled with 0, 0.1, 0.5, 1 and 5 mg Uf-Ni and Std-Ni, respectively. At 3 d after instillation, the body weight and wet lung weight were determined. At the same time, BALF was analyzed for lactate dehydrogenase (LDH), total protein (TP), tumor necrosis factor-alpha (TNF-alpha), and total cell and differential cell counts. The results showed that indicators of lung injury and inflammation in BALF were markedly raised with increased Uf-Ni and Std-Ni for each from 0 to 1 mg, and there were no differences in the indices between instillation of Uf-Ni at 1 mg and 5 mg. The results also showed that the effects of Uf-Ni on the indices were significantly higher than those of Std-Ni. Additional groups of rats were intratracheally instilled with 1 mg of Uf-Ni or Std-Ni, and wet lung weight and BALF profiles were analyzed at 1, 3, 7, 15 and 30 d later. The effect of Uf-Ni and Std-Ni on indices that can be presumed to reflect epithelial injury and permeability (LDH or TP), and release of proinflammatory cytokine (TNF-alpha) were increased throughout the 30 d post-exposure and the effects of Uf-Ni on these indices were significantly higher than those of Std-Ni from 1 to 30 d after instillation. Moreover, the number of neutrophils and LDH activity in BALF of rats after exposure to Uf-Ni were significantly greater than those of Std-Ni-exposed rats up to 30 d after instillation. Our findings suggest that Uf-Ni has a much more toxic effect on the lung than St-Ni, but the mechanism remains to be elucidated.

Analysis of Variance↗

Direct effect of vanadium on citrate uptake by rat renal brush border membrane vesicles (BBMV).

Vanadium pentoxide is used as a catalyst and a ferrovanadium alloy ingredient in automotive steels and in jet engines and airframes. In addition, vanadium is found in fuel oils. Thus, occupational exposures to vanadium pentoxide and trioxide may occur during the cleaning of oil-fired ship boilers, and from oil-fired power station boilers. Occupational exposure to vanadium pentoxide induces green tongue, asthmatic symptoms and albuminuria with cast. Urinary citrate is freely filtered at the glomerulus, and its reabsorption in the proximal tubule is the major determinant of the rate of renal excretion. In this study, we exposed rat renal brush border membrane vesicles (BBMV) to vanadium pentoxide and examined their citrate uptake characteristics. The preincubation of BBMV with 1 mM V2O5 for 8 hours significantly inhibited citrate uptake compared with that of BBMV without V2O5, preincubation. These findings indicate that the preincubation of BBMV with vanadium pentoxide results in a time-dependent inhibition of citrate uptake by BBMV. These findings might contribute to nephrotoxicity in vanadium exposure.

Animals↗