1.Etiological Studies on the Gallbladder Cancer Clustered in the Niigata Plains.
Journal of the Japanese Association of Rural Medicine 1996;44(6):795-803
Geographical distribution of standardized mortality ratio (SMR) for biliary tract cancer (BTC) showed a characteristic clustering pattern; high in the northeastern regions and low in the southwestern regions of Japan. Among the 47 prefectures (corresponding to counties in the U. S.) with high SMRs, Niigata Prefecture has been the highest in both sexes for the last two decades. It was found that the cities, towns and villages in Niigata where the mortalities from BTC were high were correspondent with rice producing areas.
In addition, it was revealed that the sources of tap water in the cities with high SMRs in Niigata were commonly big rivers, whereas in those with low SMRs they were either reservoirs located in the mountains, underground water or small river originating from the mountains. Based on these findings, the contamination of tap water by agricultural chemicals form paddy fields was suspected as a cause of the high mortality from BTC. Among several chemicals examined, diphenylether herbicide, chlornitrofen (CNP) and its derivative (CNP-amino) were detected high in tap water in the cities with higher SMRs and they seem to be related to the occurrence of BTC, particularly of female gallbladder cancer.
2.Epidemiological Studies on the Distribution and Determinants of Biliary Tract Cancer
Environmental Health and Preventive Medicine 2002;7(6):223-229
With the help of my colleagues, I have been conducting epidemiological studies on biliary tract cancer (BTC), including gallbladder cancer (GBC) and extrahepatic bile duct cancer (BDC), in Japan and Chile for about 19 years. Clustered areas with high mortality rates, especially for female GBC were found to correspond with places or prefectures in Japan that were famous for rice production. The roles of known risk factors, such as gallstones and cholecystitis, were examined, but no single factor was implicated in the high mortality rates for GBC in these areas. A working hypothesis, called the “rice production hypothesis” was formulated; this initial hypothesis was replaced by a new multifactorial causation hypothesis: GBC is more likely to occur in individuals with a genetic susceptibility and a past history of gallstones or cholecystitis who are exposed to geographically specific environmental factors, such as agricultural chemicals. On the basis of various analytical studies, it is concluded that a certain agricultural chemical was responsible for the occurrence of GBC. At the time of writing, no evidence has been obtained to disprove our hypothesis. We have also conducted international collaborative studies in Chile, which has the highest mortality rate for GBC in the world. Bile from Chileans was found to have a higher mutagenic activity than that from Japanese subjects; Chileans with a history of constipation or a habit of consuming red chilli pepper had a high risk of developing GBC, if they also had gallstone(s). The presence of a regional difference in p53 mutagenesis was also observed.
seconds
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Gallstones
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Mortality Vital Statistics
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Cancer of Biliary Tract
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Spatial Distribution
3.Effects of Hot Deep Seawater Bathing on the Immune Cell Distribution in Peripheral Blood from Healthy Young Men
Yasuo TSUCHIYA ; Tomihiro SHIMIZU ; Teruyuki TAZAWA ; Kazutoshi NAKAMURA ; Masaharu YAMAMOTO
Environmental Health and Preventive Medicine 2003;8(5,6):161-165
Objectives: Deep seawater (DSW) utilization technology has been developed for the fields of medicine and health, among others. To clarify the health effects of DSW as compared with surface seawater (SSW) or tap water (TW), we investigated the changes of immune cell distribution of the peripheral blood, or subjective judgment scores, after hot water bathing. Methods: Ten healthy young men were immersed for 10 min in DSW, SSW and TW heated to 42°C. Blood samples were collected before bathing, immediately after bathing and 60 min after bathing. Total and differential numbers of leucocytes and lymphocyte subsets (CD3, CD4, CD8, CD19, CD16, and CD56) were examined using an automated hematology analyzer and a flow cytometer, respectively. The subjective judgment scores were obtained by an oral comprehension test. Results: Since the pre-bathing leukocyte count in the TW group was significantly different from those in the DSW and SSW groups, we excluded the findings of TW bathing from consideration. In hot DSW bathing, CD8-lymphocytes increased significantly immediately after bathing (p<0.05), in contrast to hot SSW bathing, in which no significant changes were detected in the lymphocyte subsets. Additionally, there were no significant changes between repeated measurements in the subjective judgment scores, though the score of thermal sensation in SSW bathing showed a significantly higher value immediately after bathing than before bathing (p<0.01). Conclusions: Our findings suggest that increased CD8-lymphocytes in hot DSW bathing may improve human immune function as well as hot springs do, as compared with SSW bathing. Although hot DSW bathing may have the ability to change human immune cell distribution, well-designed studies are needed to clarify the health effects including not only DSW and SSW but also TW.
Bathing self care
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Treated with
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Cells
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Deep
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Antigens, CD8
4.Vitamin D Nutritional Status of Women Living on a Solitary Island in Japan
Kazutoshi NAKAMURA ; Mitsue NASHIMOTO ; Kazuo ENDOH ; Masaharu YAMAMOTO
Environmental Health and Preventive Medicine 2000;5(2):49-52
Objective: Serum 25−hydroxyvitamin D [25(OH)D] is a vitamin D metabolite and a good indicator of vitamin D nutritional status. Low 25(OH)D levels accelerate age−related bone loss in women. The aim of this study was to assess 25(OH)D levels using population−based samples from women in a community in Japan. Subjects and Methods: Of all 187 adult women living on a solitary island (Niigata, Japan), 150 (80.2%) were enrolled in a cross−sectional study in early June 1998. After excluding 6 subjects who were undergoing treatment for osteoporosis, 144 female subjects were analyzed. Serum 25(OH)D2 and 25(OH)D3 were determined by high−performance liquid chromatography. The sum of 25(OH)D2 and 25(OH)D3 was calculated, yielding 25(OH)D, for which a concentration of less than 30 nmol/L was defined as vitamin D insufficiency. Demographic data such as age, height, weight, and body mass index (BMI) were also recorded. Results: The average age of the subjects was 61.3 years (SD 12.8), ranging from 21 to 87. The average concentrations of 25(OH)D2 and 25(OH)D3 were 0.5nmol/L (SD 3.2) and 64.6nmol/L (SD 17.6), respectively. The number of subjects with 25(OH)D concentration less than 30nmol/L was 4 of 149(2.7%). Serum 25(OH)D concentrations were not significantly correlated with age (r=−0.065, p=0.441) or BMI (r=0.086, p=0.310). Conclusion: The present population−based study confirms adequate levels of 25(OH)D and low prevalence of vitamin D insufficiency in Japanese women. Further research should be directed toward clarifying which dietary factors determine vitamin D nutrition.
hydroxyl group
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Upper case dee
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Vitamin D
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Nutritional status
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Human Females
5.Study of the Suitability and Reliability of Evaluations of Initial Objective Structured Clinical Examinations at the Niigata University School of Medicine.
Eiichi SUZUKI ; Masaaki ITO ; Yutaka AOYAGI ; Ichiro FUSE ; Keiko TANAKA ; Makoto NAITO ; Masaharu YAMAMOTO
Medical Education 2003;34(1):37-44
At the Niigata University School of Medicine, objective structured clinical examinations (OSCEs) were performed for the first time in 2001 for 92 fourth-year medical students. The average evaluation scores students received from instructors were summarized, and the differences between scores given by different instructors were examined. We found that practice methods for the medical interview and physical examination before OSCE and the question topics and evaluation methods of OSCE were appropriate, but scores on some items were extremely low. The standardization and objectivity of the evaluation were satisfactory, perhaps because one explanatory conference and two training conferences were held for instructors before OSCE. However, some questions tended to produce differences between instructors, as did some topics, especially in the medical interview. The scores with standardized patients and those by teachers were strongly correlated, but those with the former were lower than those by the latter.
6.Changes in pancreatic cancer mortality, period patterns, and birth cohort patterns in Japan: analysis of mortality data in the period 1968-2002.
Takayuki SEINO ; Hiroto NAKADAIRA ; Kazuo ENDOH ; Masaharu YAMAMOTO
Environmental Health and Preventive Medicine 2008;13(4):234-242
OBJECTIVESThe 5-year survival rate for pancreatic cancer is known to be lower than that for cancer at any other site in the body, and the proportion of pancreatic cancer deaths among all cancer deaths has been increasing in Japan. The aim of this study was to investigate pancreatic cancer mortality in the light of temporal and geographical trends in the 47 prefectures of the country between 1968 and 2002.
METHODSTo survey the geographical aspects of pancreatic cancer mortality, we mapped the direct age-adjusted mortality rates of persons aged 40 years and older by sex in seven 5-year periods (1968-1972 to 1998-2002). We also evaluated the changes in period and birth cohort trends using estimable functions based on the age-period-cohort models in each prefecture.
RESULTSDuring the observation period the Hokkaido and Tohoku regions had high mortality rates for both sexes. No significant increase in period trends was observed from 1973 to 2002, but significant increases in cohort trends were observed from 1913 to 1962-in two prefectures, for males, and in four prefectures, for females.
CONCLUSIONSThe results of this study reveal a combination of time trends in pancreatic cancer mortality and changes in period or birth cohort trends. The changes in cohort trends in each prefecture were more variable than the period trends. This finding probably indicates the need for further investigation of the cohort-related factors involved in the prevalence of pancreatic cancer. Further research on mortality in the 47 prefectures needs to be conducted while taking the two time effects into account.
7.Randomized controlled trial to evaluate effectiveness of exercise therapy (Takizawa Program) for frail elderly.
Mitsuyo MAKITA ; Hiroto NAKADAIRA ; Masaharu YAMAMOTO
Environmental Health and Preventive Medicine 2006;11(5):221-227
OBJECTIVEAlthough exercise therapy intervention for frail elderly people was not of great interest in the past, it has recently drawn attention as a method to prevent and improve conditions requiring care since the enforcement of the Long-Term Care Insurance Law and the revision of the long-term care insurance system. This randomized controlled trial was performed to evaluate the effects of exercise therapy using the Takizawa Program.
METHODSIn this randomized controlled trial, we evaluated the effects of exercise therapy on the frail elderly, including those who need a high level of care, in terms of two factors: the range of motion and the functional independence measure. The subjects were 145 females admitted to special nursing homes for the elderly. They were stratified according to their care levels and randomly assigned to either the exercise therapy intervention group or the control group.
RESULTSThe range of motion values in the flexions of both shoulders, the right knee extension, and the dorsal flexions of both ankles significantly increased only in the exercise therapy intervention group. The functional independence measure score did not improve in the exercise therapy intervention group.
CONCLUSIONExercise therapy should be used for the frail elderly requiring a high level of care.
8.Epidemiological studies on the distribution and determinants of biliary tract cancer.
Environmental Health and Preventive Medicine 2003;7(6):223-229
With the help of my colleagues, I have been conducting epidemiological studies on biliary tract cancer (BTC), including gallbladder cancer (GBC) and extrahepatic bile duct cancer (BDC), in Japan and Chile for about 19 years. Clustered areas with high mortality rates, especially for female GBC were found to correspond with places or prefectures in Japan that were famous for rice production. The roles of known risk factors, such as gallstones and cholecystitis, were examined, but no single factor was implicated in the high mortality rates for GBC in these areas. A working hypothesis, called the "rice production hypothesis" was formulated; this initial hypothesis was replaced by a new multifactorial causation hypothesis: GBC is more likely to occur in individuals with a genetic susceptibility and a past history of gallstones or cholecystitis who are exposed to geographically specific environmental factors, such as agricultural chemicals. On the basis of various analytical studies, it is concluded that a certain agricultural chemical was responsible for the occurrence of GBC. At the time of writing, no evidence has been obtained to disprove our hypothesis. We have also conducted international collaborative studies in Chile, which has the highest mortality rate for GBC in the world. Bile from Chileans was found to have a higher mutagenic activity than that from Japanese subjects; Chileans with a history of constipation or a habit of consuming red chilli pepper had a high risk of developing GBC, if they also had gallstone(s). The presence of a regional difference in p53 mutagenesis was also observed.
9.Prevalence of attention-deficit/hyperactivity disorder (ADHD) symptoms in preschool children: discrepancy between parent and teacher evaluations.
Yukio SOMA ; Kazutoshi NAKAMURA ; Mari OYAMA ; Yasuo TSUCHIYA ; Masaharu YAMAMOTO
Environmental Health and Preventive Medicine 2009;14(2):150-154
OBJECTIVEClarifying the characteristics of attention-deficit/hyperactivity disorder (ADHD) symptoms in childhood is important for the prevention and management of this disorder. The purpose of this study was to determine the prevalence of ADHD symptoms in Japanese preschool children based on evaluations performed by parents or teachers.
METHODSA questionnaire survey was performed to evaluate the estimated prevalence of ADHD symptoms in preschool children in Niigata City, Japan. The first survey, conducted in 2003, involved an evaluation of ADHD symptoms by their school teachers. The second survey, conducted in 2006, involved an evaluation of the symptoms by parents. The teacher survey included 9,956 children, and the parent survey included 7,566 children. Parents and teachers assessed ADHD symptoms in children using a 14-item questionnaire based on DSM-III-R. Children with a score of 8 or higher were classified as having ADHD symptoms.
RESULTSThe overall prevalence of ADHD symptoms was 2,349/7,566 (31.1%) in the parent survey and 431/9,956 (4.3%) in the teacher survey, with a prevalence ratio of 7.2 (95% CI: 6.5-7.9). Likelihood ratio test indicated that variables significantly associated with the presence of ADHD symptoms were gender, age, school type, interaction between gender and observer, and interaction between school type and observer (each with P < 0.0001).
CONCLUSIONSThe large difference between the estimated prevalence of ADHD symptoms in Japanese preschool children from teacher and parent surveys suggests that compared to teachers, parents consider their children's symptoms much more serious. Thus, parental evaluation of ADHD symptoms using DSM criteria may be inappropriate for ADHD screening.
10.Effects of physical exercise on fall risk factors in elderly at home in intervention trial.
Ryosaku KOBAYASHI ; Hiroto NAKADAIRA ; Kazuo ISHIGAMI ; Keiko MUTO ; Shizuki ANESAKI ; Masaharu YAMAMOTO
Environmental Health and Preventive Medicine 2006;11(5):250-255
OBJECTIVEIn this study, we used an intervention approach to examine the effects of physical exercise on elderly people living at home in a rural area.
METHODSTwo regions in a village were randomly assigned as the control and intervention regions. The subjects were 60 years of age or older and were able to carry out their activities of daily living independently. The numbers of subjects were 56 and 81 for the control and intervention regions, respectively. In the control region, lectures on health were provided twice. In the intervention region, instructions on ten types of physical exercise were provided six times during this three-month study. In addition, the subjects in the intervention region were instructed to do, exercises by themselves at home three days per week. The effects were compared by evaluating motor functions in maximum step length, 10-m full-power walking parameters, right knee extension torque, right hip flexion torque, and stepping time on a 40-cm staircase; data were obtained before and after the intervention.
RESULTSAnalysis of covariance (ANCOVA) showed significant improvements in right maximum step length, the mean of the right and left maximum step lengths, and right hip flexion torque in the intervention region.
CONCLUSIONThe three-month physical exercise program improves the motor functions of the elderly.