Association between Dairy Product intake and Risk of Osteoporotic Fractures in Postmenopausal Japanese Women: Secondary Analysis of 15-Year Follow-Up data from the Japanese Population-Based Osteoporosis (JPOS) Cohort Study

OBJECTIVES

Few prospective cohort studies have evaluated the relationship between dairy product intake frequency and risk of osteoporotic fractures in Asians. This study aimed to investigate the association between habitual dairy product intake and risk of osteoporotic fractures.

DESIGN

Secondary analysis of prospective cohort study.

SETTING

Five municipalities of Japan.

PARTICIPANTS

This study included 1,429 postmenopausal Japanese women (age ≥45 years at baseline).

MEASUREMENTS

Baseline milk-intake frequency was obtained using nurse-administered questionnaires. Intakes of yogurt and cheese, and estimated calcium intake, were assessed using a validated food frequency questionnaire. Osteoporotic fracture was defined as a clinical fracture diagnosed using radiography. Hazard ratios (HRs) with 95% confidence intervals (CIs) were estimated using Cox proportional hazards models.

RESULTS

Over a median follow-up period of 15.1 years (interquartile range [IQR], 10.1-15.4 years; total, 18,118 person-years), 172 women sustained at least one osteoporotic fracture. The proportions of participants with milk intakes <1, 1, and ≥2 cups/d were 34.4%, 48.0%, and 17.6%, respectively. After adjustment for age, frequency of yogurt intake, frequency of cheese intake, body mass index, history of osteoporotic fractures, and frequency of natto intake, the HRs compared with that for milk intake <1 cup/d were 0.71 (95% CI: 0.51-0.98) and 0.57 (95% CI: 0.35-0.92) for 1 cup/d and ≥2 cups/d, respectively. After adjustment for bone mineral density, HR significance for milk intakes ≥2 cups/d remained significant. Yogurt and cheese intakes were not related to the risk of osteoporotic fractures.

CONCLUSION

High habitual milk intake, but not a habitual yogurt or cheese intake is associated with a decreased risk of osteoporotic fractures, independent of bone mineral density, in postmenopausal Japanese women.

Predictive ability of novel volumetric and geometric indices derived from dual-energy X-ray absorptiometric images of the proximal femur for hip fracture compared with conventional areal bone mineral density: the Japanese Population-based Osteoporosis (JPOS) Cohort Study

Areal BMD (aBMD) from DXA is not a sufficiently accurate predictor of fracture. Novel volumetric BMD derived from 3D modeling of the hip from DXA images significantly improved the predictive ability for hip fracture relative to aBMD at the femoral neck, but not aBMD at the total hip.

INTRODUCTION

To clarify whether volumetric and geometric indices derived from novel three-dimensional (3D) modeling of the hip using dual-energy X-ray absorptiometric (DXA) images improve hip fracture prediction relative to areal bone mineral density (aBMD).

METHODS

We examined 1331 women who had completed the baseline survey and at least one follow-up survey over 20 years (age 40-79 years at baseline). Each survey included aBMD measurement at the hip by DXA. Volumetric and geometric indices of the hip at baseline and the 10-year follow-up were estimated from DXA images using a 3D modeling algorithm. Incident hip fractures during the 20-year follow-up period were identified through self-report. Cox proportional hazards regression models allowing for repeated measurements of predictors and outcomes were constructed, and their predictive ability for hip fracture was evaluated using areas under receiver operating characteristic curves (AUCs) and net reclassification improvement (NRI) over aBMD at the femoral neck (FN) and total hip (TH) as references.

RESULTS

During a median follow-up of 19.8 years, 68 incident hip fractures were identified (2.22/1000 person-years). A significantly larger AUC of trabecular volumetric BMD (vBMD) at the total hip (AUC = 0.741), femoral neck (AUC = 0.748), and intertrochanter (AUC = 0.738) and significant NRI (0.177, 0.149, and 0.195, respectively) were observed compared with FN-aBMD (AUC = 0.701), but not TH-aBMD.

CONCLUSIONS

vBMD obtained from 3D modeling using routinely obtained hip DXA images significantly improved hip fracture risk prediction over conventional FN-aBMD, but not TH-aBMD.

TRIAL REGISTRATION

The Japanese Population-Based Osteoporosis (JPOS) Cohort Study was retrospectively registered as UMIN000032869 in the UMIN Clinical Trials Registry on July 1, 2018.

Correction to: Age-related normative values of trabecular bone score (TBS) for Japanese women: the Japanese Population-based Osteoporosis (JPOS) study

I have, as the Principal Investigator of this study, identified an error in the computation of TBS values in the JPOS cohort, which resulted in the publication of incorrect TBS absolute values [1]. This error was linked to the calibration process for calculating standardized TBS values in the R&D TBS.

Total 25-hydroxyvitamin D levels predict fracture risk: results from the 15-year follow-up of the Japanese Population-based Osteoporosis (JPOS) Cohort Study

We found that community-dwelling women with 25-hydroxyvitamin D levels <20 ng/mL compared to levels ≥20 ng/mL indicated increased risks for clinical, non-vertebral, and fragility fractures during 5 years. Furthermore, the increased risks of non-vertebral fractures remained significant in 10 and 15 years after adjusting for age and bone mineral density.

INTRODUCTION

We examined whether total 25-hydroxyvitamin D (25[OH]D) levels are associated with fracture risk over 15 years in a Japanese female cohort.

METHODS

Of 1437 community-dwelling women aged ≥50 years in the baseline survey, 1236 provided information regarding fractures during a 15-year follow-up period. The analysis included 1211 women without early menopause or diseases affecting bone metabolism.

RESULTS

Over 15 years, 269 clinical (224 non-vertebral, 149 fragility) fracture events were confirmed. Incidence rates categorized by 25(OH)D levels (<10, 10-20, 20-30, and ≥30 ng/mL) indicated a significant divergence for any clinical fractures in 5 years (log rank test p = 0.016) and for non-vertebral fractures in 5, 10, and 15 years (p < 0.001, p = 0.001, p = 0.017, respectively). Hazard ratios (HRs) for 25(OH)D levels <10 and 10-20 ng/mL compared to levels ≥30 ng/mL during 5 years indicated significances for clinical fractures (HR 4.93 with p = 0.009, HR 3.00 with p = 0.034) and for non-vertebral fractures (HR 6.55 with p = 0.005, HR 3.49 with p = 0.036). Those with levels <20 ng/mL compared to those with levels ≥20 ng/mL indicated significant increased risks for clinical fractures (HR 1.72 with p = 0.010), non-vertebral fractures (HR 2.45 with p < 0.001), and fragility fractures (HR 2.00 with p = 0.032) in 5 years. The HR of non-vertebral fractures for levels <20 ng/mL remained significant during 15 years (HR 1.42 with p = 0.012) after adjustment for age and femoral neck bone mineral density.

CONCLUSIONS

Low 25(OH)D levels, especially <20 ng/mL, were associated with elevated fracture risks in Japanese women.

Age-related normative values of trabecular bone score (TBS) for Japanese women: the Japanese Population-based Osteoporosis (JPOS) study

Trabecular bone score (TBS), a surrogate measure of bone microarchitecture, represents fracture risk independently of bone density. We present normative TBS values from a representative population study of Japanese women. This database would enhance our understanding of trabecular bone microarchitecture and improve osteoporosis management.

INTRODUCTION

TBS is a texture parameter that quantifies local variation in gray level distribution within dual-energy X-ray absorptiometry (DXA) images of the lumbar spine. While TBS is associated with fracture risk independently of areal bone mineral density (aBMD), normative TBS values have only been reported for Caucasian women. This study provides age-specific normative values of TBS from a representative sample of Japanese women.

METHODS

We randomly selected 4,550 women aged 15-79 years from 7 areas throughout Japan. Women younger than 20 years and those with any medical history which might affect bone metabolism were excluded, and the remaining 3,069 with at least two assessable vertebrae from the first to the fourth vertebrae were subjected to analysis. TBS values were calculated from spine DXA images using TBS iNsight software (Med-Imaps, France). Age-related models of TBS were constructed using piecewise linear regression analysis.

RESULTS

Participant age, body mass index (BMI), spine aBMD, and TBS (mean ± SD) were 48.7 ± 16.8 years, 22.9 ± 3.4, 0.888 ± 0.169 g/cm(2), and 1.187 ± 0.137, respectively. A three-piece linear regression model of TBS on age explained 70.7% of the total variance in TBS and comprised very small age-related changes in the youngest segment of the regression line, rapid loss in the middle segment, and small loss in the oldest segment. TBS was lower in Japanese women than in Caucasian women across all age ranges, with the difference increasing with age up through 65 years.

CONCLUSIONS

The normative values of TBS for Japanese women presented here would enhance our understanding of trabecular bone microarchitecture and help improve the management of osteoporosis.

Biochemical markers for bone turnover predict risk of vertebral fractures in postmenopausal women over 10 years: the Japanese Population-based Osteoporosis (JPOS) Cohort Study

We evaluated how bone turnover might predict vertebral fracture risk in postmenopausal women over 10 years. After adjusting for age and femoral neck bone mineral density, high bone-specific alkaline phosphatase and total and free deoxypyridinoline at baseline predicted increased vertebral fracture risk in women with ≥ 5 years since menopause.

INTRODUCTION

The aim was to evaluate the ability of bone turnover markers (BTMs) in predicting vertebral fractures.

METHODS

Participants in the 1996 baseline survey of the JPOS Cohort Study included 522 postmenopausal women, with no diseases or medications affecting bone metabolism. Vertebral fractures were ascertained in three follow-up surveys (1999, 2002, and 2006). Initial fracture events were diagnosed morphometrically. The Poisson regression model was applied to estimate the rate ratio (RR) of the following log-transformed BTM values at baseline: osteocalcin and bone-specific alkaline phosphatase (BAP) in serum and C-terminal cross-linked telopeptide of type I collagen, total deoxypyridinoline (tDPD), and free deoxypyridinoline (fDPD) in urine.

RESULTS

Eighty-three fracture events were diagnosed over a median follow-up period of 10.0 years. RR per standard deviation (SD) (95 % confidence interval) for BAP was 4.38 (1.45, 13.21) among 65 subjects with years since menopause (YSM) < 5 years. RRs per SD (95 % confidence interval) for BAP, tDPD, and fDPD were 1.39 (1.12, 1.74), 1.32 (1.05, 1.67), and 1.40 (1.12, 1.76), respectively, after adjusting for age and femoral neck bone mineral density (FN BMD) among 457 subjects with YSM ≥ 5 years. Of the 451 women followed at least once until 2002, RRs per SD for BAP, tDPD, and fDPD adjusted for age and FN BMD over 6 years were not significantly different from those over 10 years.

CONCLUSION

BAP was associated with vertebral fracture risk among early postmenopausal women. BTMs can predict vertebral fractures independently of BMD among late postmenopausal women over a 10-year follow-up period.

Obesity and cardiac autonomic nerve activity in healthy children: Results of the toyama birth cohort study

OBJECTIVES

To determine the relationship between obesity and cardiac autonomic nerve activity in healthy children.

METHODS

16 healthy male children comprising of 9 nonobese and 7 obese subjects (body mass index > 19.1 kg/m(2)) aged 8-9 years were selected. Electrocardiograms were measured for 10 min. under controlled ventilation (0.25 Hz) in the supine position. Consecutive 256-second RR interval data were transformed by the Fast Fourier Transform method into power spectral data. Very low frequency (VLF; 0.003-0.04 Hz), low frequency (LF; 0.04-0.15Hz), high frequency (HF; 0.15-0.40Hz), and total power (TP; 0.003-0.40Hz) were calculated and transformed into a natural logarithm (In). Normalized units (nu) were also calculated as follows: LFnu=LF/(TP-VLF)x100. HFnu=HF/(TP-VLF)x100. Low/high-frequency ratio (LHR) was calculated as LF divided by HF. Unpaired t test was performed to compare the 2 groups.

RESULTS

TP In and HFnu, reflecting cardiac parasympathetic nerve activity, in obese children were significantly lower than those in nonobese children. In contrast, LFnu and LHF, reflecting cardiac sympathetic nerve activity, in obese children were significantly higher than those in nonobese children.

CONCLUSIONS

These findings suggest that obese children have higher sympathetic nerve activity and lower parasympathetic nerve activity than nonobese children.

A meta-analysis of epidemiological studies on the relationship between occupational electromagnetic field exposure and the risk of adult leukemia

Since the first paper by Milham et al. suggested that occupational exposure to an electromagnetic field (EMF) could increase the risk of adult leukemia, many epidemiological studies on this problem have been published. In this report the method of meta-analysis was used to summarize the results from these papers quantitatively. The combined relative risk of all leukemia (RR=1.11), as well as acute lymphocytic leukemia (RR=1.38), acute myeloid leukemia (RR=1.07) and chronic lymphocytic leukemia (RR=1.14) increased but not significantly. So far, it is difficult to make a consistent conclusion about the relationship of the occupational exposure to EMF and adult leukemia. Further carefully designed case-control and cohort studies using the more valid means of exposure assessment are required.

Influence of Behavioral and Environmental Factors on the Development of Obesity in Three-year-old Children -A Case-Control Study Based on Toyama Study-

Obesity in children seems to be a risk factor for chronic diseases in adulthood. From the viewpoint of preventive medicine, factors influencing the development of obese children should be removed early in life.The purpose of this study was to the elucidate relationship between obesity in 3-year-old children and both behavioral and environmental factors by conducting a case-control study. Subjects were selected from the Toyama study. Matched-pair comparisons were performed between obese children whose Kaup's index was 18 or more (N=117) and control children (N=234) . Multivariate stepwised logistic regression analysis also applied to assess influence of confounding factors.The results indicated that the following 6 factors significantly influenced the development of obese 3-year-old children in exact Fisher's method analysis (p<0.05): person other than the mother responsible for taking care of the child, short sleep duration (9 hours or less), physical inactivity, eating snacks irregularly, overweight father (BMI≥24), and overweight mother (BMI≥24). For both sexes, after adjusting for confounders by multivariate stepwise logistic analysis, overweight mother (OR 2.54, 95 % CI 1.64-3.95), birth overweight (birth weight≥3,500g; OR 1.76, 95 % CI 1.15-2.69), the mother not responsible for taking care of the child (OR 1.65, 95% CI 1.10-2.48), overweight father (OR 1.62, 95%CI 1.09-2.40), eating snacks irregularly (OR 1.56, 95% CI 1.04-2.33), and gender (female;OR 0.51, 95% CI 0.34-0.77) had significant relationships with obesity in childhood. For boys, overweight mother (OR 2.53, 95 % CI 1.47-4.35), birth overweight (OR 2.03, 95%CI 1.22-3.39), eating snacks irregularly (OR 1.94, 95 %CI 1.19-3.18), and birth month (36-41 months; OR 0.47, 95 % CI 0.23-0.96) had significant relationships. For girls, overweight mother (OR 2.62, 1.28-5.35), and short sleep duration (OR 2.24, 1.11-4.52) had significant relationships. In neither Fisher's exact method nor multivariate logistic models, time to wake up, bedtime, duration of playing outdoors, regularity of meals, care about salty food, or frequency of eating snacks had significant relations with obesity in 3-year-old children (p<0.05).

Association between weight changes and changes in hip geometric indices in the Japanese female population during 10-year follow-up: Japanese Population-based Osteoporosis (JPOS) Cohort Study

During a 10-year follow-up of 893 women of various ages from the Japanese Population-based Osteoporosis Cohort Study, we evaluated the relationship between weight changes and hip geometric strength assessed by hip structure analysis. Our findings suggest that maintaining weight may help retain geometric strength and reduce hip fracture risk.

INTRODUCTION

The effects of changes in anthropometric indices on hip geometry in women of various ages are unclear. We evaluated these effects by analyzing 10-year longitudinal data from a representative sample of Japanese women.

METHODS

Dual-energy X-ray absorptiometry scans of the proximal femur were performed at baseline and at the 10-year follow-up. Data were analyzed with the Hip Structure Analysis (HSA) program, which yields geometric strength indices including cross-sectional area (CSA), section modulus (SM) and subperiosteal diameter (PD) at regions of interest (ROIs) in the narrow neck (NN), intertrochanter, and femoral shaft (FS) regions. Annual percent change of each HSA index was determined. Height and weight were measured at baseline and follow-up.

RESULTS

After excluding subjects with factors affecting bone metabolism, we evaluated 893 women (18-79 years old at baseline). The greatest changes in most HSA indices during the follow-up were observed in subjects aged ≥ 70 years at all ROIs. PD modestly but significantly expanded with age, but this change was not significant in subjects aged ≥ 70 years or those who had entered menopause ≥ 20 years before baseline. An increasing trend in weight was associated with an increase or smaller decline in CSA and SM at the NN and FS regions regardless of menopausal status after adjusting for age, height, and weight at baseline and change of estimated volumetric bone mineral density. Changes in height showed a much weaker association with HSA indices.

CONCLUSIONS

Maintaining weight may help retain hip geometric strength and reduce the risk of hip fracture.

Fracture risk prediction using FRAX®: a 10-year follow-up survey of the Japanese Population-Based Osteoporosis (JPOS) Cohort Study

We evaluated the predictive ability of FRAX® in a cohort of 815 Japanese women. The observed 10-year fracture rate did not differ significantly from that predicted by FRAX®. The predictive ability of FRAX® without femoral neck bone mineral density (BMD) was similar to that with femoral neck BMD.

INTRODUCTION

We evaluated the ability of the Japanese version of FRAX®, a World Health Organization fracture risk assessment tool, to predict the 10-year probability of osteoporotic fracture.

METHODS

Self-reported major osteoporotic fracture (N = 43) and hip fracture (N = 4) events were ascertained in the 10-year follow-up survey of the Japanese Population-Based Osteoporosis Cohort Study. Participants were 815 women aged 40-74 years at the baseline survey. Receiver operating characteristic curve analysis compared FRAX® with multiple logistic models based on age, body weight, and femoral neck BMD.

RESULTS

The number of observed major osteoporotic or hip fracture events did not differ significantly from the number of events predicted by the FRAX® model (with or without BMD). The area under the curve (AUC) value for FRAX® with BMD for predicting major osteoporotic fractures was similar to that of a logistic model with age, body weight, and BMD (0.69 vs. 0.71, respectively; p = 0.198); the AUC of FRAX® with BMD for predicting hip fractures was similar to that of a model based on age and BMD (0.88 vs. 0.89, respectively; p = 0.164). The AUCs of FRAX® without BMD for predicting major osteoporotic and hip fractures were similar to those with BMD (0.69 vs. 0.67, respectively; p = 0.121; 0.88 vs. 0.86, respectively; p = 0.445).

CONCLUSIONS

The Japanese version of FRAX® without BMD estimated the 10-year probability of osteoporotic fracture in this population with few clinical risk factors as similar to that of FRAX® with BMD.

Age-specific reference values of hip geometric indices from a representative sample of the Japanese female population: Japanese Population-based Osteoporosis (JPOS) Study

We analyzed 2,107 hip dual-energy X-ray absorptiometry (DXA) images from the Japanese Population-based Osteoporosis Study with the Hip Structure Analysis (HSA) program to obtain age-specific reference values of HSA indices for the Japanese female population. These references may help physicians accurately assess HSA results and aid researchers in making interracial comparisons of the indices.

INTRODUCTION

Hip geometry is expected to improve hip fracture risk assessment, which is usually assessed by bone mineral density (BMD) alone. We aimed to establish a reference database for Japanese women.

METHODS

We studied 2,107 Japanese women (15-79 years old) with no history of bone metabolism-related diseases from the Japanese Population-based Osteoporosis Study performed in 1996. Hip geometry was conducted on DXA images with the HSA program, which yielded data for cross-sectional area (CSA), subperiosteal diameter (PD), endocortical diameter (ED), mean cortical thickness (CT), section modulus (SM), and buckling ratio at the narrow neck (NN), intertrochanter (IT), and femoral shaft (FS) regions. Mean HSA indices were determined for each 5-year age group after adjustment for height and weight based on most recent Japanese population values.

RESULTS

Age-related changes in HSA indices were evident for the 50-54 year group in the NN and IT regions and for the 55-59 year group in the FS region; these changes increased with age thereafter. Age-related changes in CSA and CT were almost identical to that of BMD. Japanese subjects exhibited BMD and CT values similar to those reported for US non-Hispanic white women, but had 16-23% smaller SM values. CSA and CT were highly correlated with conventional BMD, whereas ED, SM, and PD showed lower correlations.

CONCLUSIONS

Age-specific reference values of HSA indices for the Japanese female population were obtained. This database will form the foundation for accurate HSA result evaluation.

Prevalent vertebral deformity independently increases incident vertebral fracture risk in middle-aged and elderly Japanese women: the Japanese Population-based Osteoporosis (JPOS) Cohort Study

SUMMARY

Prevalent vertebral deformity increases incident vertebral fracture risk according to studies focusing primarily on Caucasian elderly populations. We report a 3-fold increase in this risk in a population-based cohort of Japanese women after adjusting for subject propensity for having vertebral deformities. This relationship tended to be stronger in middle-aged women.

INTRODUCTION

Evidence on increased risk of incident vertebral fractures associated with vertebral deformity in middle-aged women is limited. We aimed to evaluate this risk in a population-based cohort of Japanese women.

METHODS

We followed 712 women aged 50-79 years at baseline randomly selected from 3 municipalities in Japan for 6 years. McCloskey-Kanis criteria identified vertebral deformities on X-ray absorptiometric images. At follow-up, vertebra with > or = 20% height reduction from baseline were considered incident fractures. Rate ratio (RR) of incident fracture for prevalent vertebral deformities was calculated using the Poisson regression equation adjusted for propensity of having vertebral deformities based on potential risk factors.

RESULT

Vertebral fractures occurred in 73 women (10.3%). Crude RR of vertebral deformity-associated fracture was 4.63 [95% confidence interval (CI), 3.04-7.04] and decreased to 2.96 (95% CI, 1.77-4.94) after propensity score adjustment. Adjusted RR was generally greater in younger women at 7.19 (95% CI, 1.04-49.6), 3.19 (95% CI, 1.27-7.97), and 2.34 (95% CI, 1.33-4.11) for women aged 50-59, 60-69, and 70-79 years, respectively (p = 0.0527 for those aged 50-59 vs 70-79).

CONCLUSION

Vertebral deformity was associated with a 3-fold increase in subsequent vertebral fracture risk in Japanese women, and this association was stronger in middle-aged women.

Peroxisome proliferator-activated receptor gamma polymorphism is related to peak bone mass: the JPOS study

We analyzed 1,217 women to examine the effect of peroxisome proliferator-activated receptors gamma (PPARgamma) C161 --> T on bone status. Among 664 premenopausal women, the C161 --> T is associated with low bone mineral density (BMD) at the total hip and femoral neck. Moreover, the odds ratio for osteopenia or osteoporosis at the femoral neck was 1.98 for premenopausal CT/TT genotypes.

INTRODUCTION

The impact of PPARgamma on BMD has not been conclusively established. We examined if PPARgamma C161T polymorphism is associated with BMD and its change.

METHODS

We conducted a baseline survey in 1996 and a 10-year follow-up survey, Japanese Population-based Osteoporosis Study, with a sample population representative of Japanese women. Of these, 1,217 participants in the 1996 survey were analyzed cross-sectionally, while longitudinal analysis was performed on 563 women. A P value < 0.0042 (=0.05/12 for three menstrual statuses and four skeletal sites) was considered statistically significant after Bonferroni correction in multiple testing for cross-sectional analysis.

RESULTS

The total hip and femoral neck BMDs were significantly higher for CC genotype than for CT/TT genotypes among 664 premenopausal women (P = 0.0020, P = 0.0022, respectively). Compared to the CC genotype, the odds ratio for osteopenia or osteoporosis (T-scores below -1) at the femoral neck was 1.98 for premenopausal CT/TT genotypes with statistical significance (P = 0.0041). Change of BMD at either skeletal site during the follow-up period was not significantly different for either menstrual status.

CONCLUSIONS

We conclude that the PPARgamma C161T is associated with low peak bone mass.

Low bone mass is associated with carotid atherosclerosis in postmenopausal women: the Japanese Population-based Osteoporosis (JPOS) Cohort Study

We analyzed 609 women belonging to the JPOS study in a 10-year follow-up survey, to examine the association of osteoporosis with atherosclerosis. Osteoporosis or prevalent vertebral fracture at baseline was associated with increased intima-media thickness of the carotid bifurcation in postmenopausal women, adjusted for age, BMI, and other variables at baseline.

INTRODUCTION

Whether low bone mass predicts increased carotid atherosclerosis has not been fully investigated.

METHODS

In 2006, we conducted a 10-year follow-up survey of 1,040 women (follow-up rate: 68.6%). We analyzed 609 women > or =50 years old in 2006 without a history of cardiovascular or connective tissue diseases at baseline. BMD and evaluation of vertebral fracture at baseline were used. The intima-media thickness of carotid bifurcation (BIF-IMT) was measured by B-mode ultrasonography in 2006.

RESULTS

Adjusted BIF-IMT values of subjects with spine T-score > or =-1, between-2.5 and -1, and <-2.5 or prevalent vertebral fracture were 1.19 mm, 1.34 mm, 1.57 mm, respectively, in women with less than 10 years since menopause (YSM) (n = 159), 1.30 mm, 1.32 mm, 1.53 mm, in women with YSM > or =10 without a history of hypertension at baseline (n = 144) (both with p < 0.05 for linear trend). Those values among no versus prevalent vertebral fracture in women with YSM > or =10 were 1.40 mm, 1.66 mm with p < 0.05 (n = 202). Those associations were independent of age, BMI, total cholesterol, smoking and drinking habits, history of diabetes mellitus, and hypertension (for women with YSM < 10) at baseline.

CONCLUSION

Osteoporosis including prevalent vertebral fracture may be associated with carotid atherosclerosis in the first 10 years of postmenopausal women.

Biochemical markers of bone turnover predict bone loss in perimenopausal women but not in postmenopausal women-the Japanese Population-based Osteoporosis (JPOS) Cohort Study

INTRODUCTION

The predictive value of biochemical markers of bone turnover for subsequent change in bone density in a population sample of healthy women with a wide range of ages has not been fully established.

METHODS

We followed 1,283 women aged 15-79 years at baseline selected randomly from the inhabitants of three areas in Japan for 6 years, and examined 1,130 subjects with no disease or administration of drugs affecting bone metabolism. The annual change in bone density at the spine, total hip, and distal one third of the radius was determined during the follow-up period by dual x-ray absorptiometry and was compared among the groups using different levels of biochemical markers at baseline, including serum osteocalcin (OC) and bone-specific alkaline phosphatase (bone ALP), free and total (tDPD) forms of immunoreactive deoxypyridinoline, and type I collagen crosslinked C-terminal telopeptide (CTX) in urine.

RESULTS

Premenopausal women aged 45 years or older with elevated levels of OC, bone ALP, CTX, or tDPD showed significantly greater bone loss at most skeletal sites during the follow-up period than those with lower levels, after adjustment for the effects of age, height, weight, dietary calcium intake, regular exercise, and current smoking. The greatest coefficient of determination of the model was observed in the association between CTX and bone loss at the hip during the first 3 years of follow-up (42.8%). These subjects were pooled with perimenopausal women at baseline, and those who still menstruated at follow-up in this pooled group showed significant but more modest associations, whereas those who entered menopause during the follow-up period showed clear associations. However, early postmenopausal women with less than 5 or 10 years since menopause showed an association that was limited mostly to the distal radius, and other postmenopausal groups had virtually no association.

CONCLUSION

Biochemical markers of bone turnover may predict bone loss in women undergoing menopausal transition but may not predict bone loss in postmenopausal women.

Effects of the Cdx-2 polymorphism of the vitamin D receptor gene and lifestyle factors on bone mineral density in a representative sample of Japanese women: the Japanese Population-based Osteoporosis (JPOS) Study

Using a large-scale representative sample of the Japanese female population, we examined the effects of a single nucleotide polymorphism within a binding site of Cdx-2 in the promoter region of the vitamin D receptor gene on bone mineral density (BMD), and the interactions between this polymorphism and lifestyle factors on BMD. Fifty women were randomly selected from each of the 5-year age-stratified populations (15-79 years) in each of three chosen municipalities as a part of the Japanese Population-based Osteoporosis Study. BMD at the lumbar spine, hip, and distal forearm was measured using dual-energy X-ray absorptiometry at baseline and again in a follow-up study conducted 3 years later. Information on lifestyle factors was collected in a questionnaire and followed up in interviews. The G-to-A polymorphism within the Cdx-2 binding site was determined by a TaqMan allelic discrimination assay. At baseline, 1,340 women were analyzed. The baseline BMD in the ultradistal forearm in premenopausal women with the GG genotype was significantly lower than in those with other genotypes. There was no association between the Cdx-2 genotype and the change in BMD at any of the skeletal sites. We found significant associations between daily milk consumption and baseline BMD at some skeletal sites but only in subjects with the GG genotype. In conclusion, the Cdx-2 polymorphism alone did not have a substantial effect on BMD in Japanese women. However, this polymorphism might have some effect in women with low calcium intake.

Associations of lifestyle factors with quality of life (QOL) in Japanese children: a 3-year follow-up of the Toyama Birth Cohort Study

PURPOSE

To examine the associations between lifestyle factors and quality of life (QOL) among Japanese children.

METHODS

Participants were 7794 children (3869 boys and 3925 girls) aged 9-10. They completed a questionnaire regarding lifestyles at baseline survey and were followed up for 3 years. In the follow-up survey, QOL was evaluated using a Japanese version of the COOP charts. Children rated their QOL as one of five response categories. Subjects rated as 'very well' or 'pretty good' were considered to have good QOL, and the remainder was assumed to have poor QOL. Logistic regression analysis was performed to evaluate the relationship between lifestyles or changes in lifestyles and QOL. In the multivariate analysis model, age, sex, body mass index (BMI), and lifestyle factors were simultaneously entered.

RESULTS

During the follow-up period, children became more sedentary. Compared to children participating in physical activity 'very often' at baseline, those who exercised 'almost never' were more likely to have poor QOL [OR (95% CI): 1.92 (1.26-2.93)]. Children who developed or maintained undesirable lifestyles had high OR for poor QOL. Compared to children taking breakfast 'often' during the follow-up period, those changing from 'often' to 'seldom' or those taking breakfast 'seldom' were more likely to have poor QOL [1.61 (1.24-2.07), 2.05 (1.03-4.09), respectively]. When compared with children maintaining their participation in physical activity 'often', those who changed from 'often' to 'seldom' and those who kept 'seldom' were more likely to have poor QOL [2.10 (1.84-2.39), 2.21 (1.88-2.59), respectively].

CONCLUSIONS

This study shows that unfavourable lifestyles in childhood are associated with poor QOL in early adolescence. Early intervention could be worth considering to keeping desirable lifestyles during childhood.

Bone mass and lifestyle related factors: a comparative study between Japanese and Inner Mongolian young premenopausal women

The purpose of this study was to evaluate the ethnic difference in bone mass between Japanese and Inner Mongolian young premenopausal women and to assess the contribution of lifestyle related and anthropometric factors to bone mass. We studied 33 Japanese and 44 Inner Mongolian healthy young women, aged 20-34 years, in urban area. Speed of sound (SOS), broadband ultrasound attenuation (BUA) and stiffness index (SI) were measured at the calcaneus using quantitative ultrasound (QUS) analysis. Age at menarche, regularity of menstruation and lifestyle related factors were estimated by a self-reported questionnaire. There were no differences between the two groups in age, height, weight, BMI, regularity of menstruation, frequency of meat intake, frequency of yellow-green vegetable intake and exercise habit. Japanese women had significantly lower age at menarche and higher proportion of milk consumption habit at junior high school, senior school and present. Before adjustment, Japanese women had significantly higher SOS and SI than Inner Mongolian women. However, after adjustment for age at menarche and milk consumption habit at junior high school, both of which were significantly different between groups, no group-differences remained in either SOS or SI. These results suggest that the differences in age at menarche and milk consumption habit at junior high school, which relate to hormonal and nutritional status during puberty, may account for the differences in bone mass between Japanese and Inner Mongolian young women.

Beneficial effects of taurine on serum lipids in overweight or obese non-diabetic subjects

Taurine has beneficial effects on lipid metabolism in experimental animals fed with high-cholesterol or high fat diets. Whether taurine benefits lipid metabolism in humans has rarely been investigated. The aim of this study was to evaluate the effects of taurine on serum lipids in overweight or obese young adults. Thirty college students (age: 20.3+/-1.7 years) with a body mass index (BMI) >/=25.0 kg/m(2), and with no evidence of diabetes mellitus were selected and assigned to either the taurine group (n=15) or the placebo group (n=15) by double-blind randomization. Taurine 3 g/day or placebo was taken orally for 7 weeks. Triacylglycerol (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and plasma glucose were measured before and after supplementation. The atherogenic index (AI) was calculated as (TC-HDL-C)/HDL-C. There were no differences in any baseline parameter between the two groups. Taurine supplementation decreased TG and AI significantly. Body weight also reduced significantly in the taurine group. These results suggest that taurine produces a beneficial effect on lipid metabolism and may have an important role in cardiovascular disease prevention in overweight or obese subjects.

Effects of taurine supplementation on VDT work induced visual stress

In order to evaluate the effects of dietary taurine supplementation on visual fatigue induced by visual display terminals (VDT) work, 25 male college students aged from 20 to 24 years who were not engaged in VDT work were selected to participate in the study. Volunteers were randomly assigned to either the taurine supplementation (n=13) or the placebo supplementation control group (n=12). Before and after 12 days of taurine (3 g/day) or placebo supplementation, two identical 2.5-hr VDT work tests were performed while recording the P100, N75 and N145 latencies and P100 amplitude of pattern visual evoked potential (PVEP) and the frequency of critical flicker fusion (CFF). Following 2.5-hr of VDT work, the P100 and N75 latencies of PVEP increased ( P<0.01) while the P100 amplitude decreased significantly ( P<0.01). The frequency of CFF also reduced significantly ( P<0.01). After 12 days of taurine supplementation, the reduction in P100 amplitude after VDT work alleviated significantly ( P<0.05). The results suggest that taurine supplementation alleviates visual fatigue induced by VDT work.

Role of taurine supplementation to prevent exercise-induced oxidative stress in healthy young men

To evaluate the protective effects of taurine supplementation on exercise-induced oxidative stress and exercise performance, eleven men aged 18-20 years were selected to participate in two identical bicycle ergometer exercises until exhaustion. Single cell gel assay (SCG assay) was used to study DNA damage in white blood cells (WBC). Pre-supplementation of taurine, a significant negative correlation was found between plasma taurine concentration before exercise and plasma thiobaribituric-acid reactive substance (TBARS) 6 hr after exercise (r = -0.642, p<0.05). WBC showed a significant increase in DNA strand breakage 6 hr and 24 hr after exercise. Seven-day taurine supplementation reduced serum TBARS before exercise ( p<0.05) and resulted in a significantly reduced DNA migration 24 hr after exercise ( p<0.01). Significant increases were also found in VO(2)max, exercise time to exhaustion and maximal workload in test with taurine supplementation ( p<0.05). After supplementation, the change in taurine concentration showed positive correlations with the changes in exercise time to exhaustion and maximal workload. The results suggest that taurine may attenuate exercise-induced DNA damage and enhance the capacity of exercise due to its cellular protective properties.

The characteristics of bone turnover in the second decade in relation to age and puberty development in healthy Japanese male and female subjects--Japanese Population-based Osteoporosis Study

BACKGROUND

There are few studies that clarify the characteristics of bone turnover in children and adolescents. Furthermore, little has been published on changes in urinary CrossLaps(TM) (CTx) in Japanese subjects.

AIM

To investigate biochemical markers of bone turnover in subjects, in relation to age and puberty development.

SUBJECTS AND METHODS

We measured serum bone specific alkaline phosphatase (B-Alp) and CTx in 1207 Japanese subjects aged 9-18 years. As an indicator of puberty development, the age that pubic hair appeared in males and menstruation started in females was obtained from questionnaires.

RESULTS

B-Alp and CTx/Cr (creatinine) had high values before and just after the indicators and was lower thereafter, reaching a plateau in both genders. There was no significant difference in these values in males 5-6 years, or 7 years and more after the appearance of pubic hair. B-Alp and CTx/Cr values 7 years and more after menarche were significantly lower than those 5-6 years after menarche, however the differences were relatively small.

CONCLUSIONS

Subjects in the second decade can be divided into three groups: 'before the appearance of pubic hair for males and menarche for females', 'up to and including 3-4 years after them' and '5-6 years and more after them'.

Age-specific values and cutoff levels for the diagnosis of osteoporosis in quantitative ultrasound measurements at the calcaneus with SAHARA in healthy Japanese women: Japanese population-based osteoporosis (JPOS) study

To establish the reference values of the quantitative ultrasound (QUS) indices in healthy Japanese women and to propose a diagnostic criterion for osteoporosis by means of the QUS indices, 659 healthy women aged 20-79 years recruited from a larger cohort study (JPOS study), were examined for bone mass measurements by QUS at the calcaneus (SAHARA, Hologic Inc., USA) and by dual-energy X-ray absorptiometry at the spine, hip, and distal forearm. We presented 10-year age-specific mean values and T-scores of the QUS indices. The pattern of decrease in the T-score appeared to be linear in the QUS indices and total hip BMD but not in BMD at the spine. The T-score of the QUS of indices of the subjects in their 70s were significantly higher than that of BMD at the spine. The prevalence rates of osteoporosis in the subjects aged 50 and older diagnosed by QUS (8.7% for SOS, 10.7% for BUA) were similar to that diagnosed by total hip BMD (11.5%) and significantly lower than that by the spine BMD (36.1%) when the WHO criteria were applied. We performed receiver-operating characteristic analysis to set a cutoff level of the QUS indices for the diagnosis of osteoporosis to accurately identify the subjects diagnosed by either the spine or total hip BMD. The highest likelihood ratios for SOS and BUA were obtained at the cutoff levels of 1,517.7 m/sec (T-score: -1.58) with the sensitivity of 0.65 and the specificity of 0.65 and 59.5 dB/MHz (T-score: -1.52) with 0.66 and 0.69, respectively. The diagnostic accuracy of QUS indices for osteoporosis was not superior to that of age. However, the QUS indices showed a significant contribution to forming the diagnosis of osteoporosis independently of age and body size in multivariate diagnostic models developed by the logistic regression analysis. Therefore, the cutoff values presented in this study may be used as a tentative criterion until the cutoff levels for the QUS indices are set according to the fracture risk.

A cross-sectional study on association of calcium intake with blood pressure in Japanese population

To investigate the association of calcium intake independently of other nutrients already known as predictors of hypertension, a cross-sectional study was carried out on the same population in Japan as used for the INTERSALT study. Dietary calcium intake was estimated from a 1-day 24-h recall. Sodium and potassium intakes were evaluated by 24-h urinary excretion. Data from 476 subjects aged 20-59 years, 230 men and 246 women, were analysed. The mean dietary calcium intake ranged from 557 to 608 mg/day among men, and from 528 to 639 mg/day among women. Among men, the pooled estimate of the regression coefficients of blood pressure (mm Hg) per 100 mg increase of calcium intake, adjusted for age and body mass index (BMI), were -0.42 mm Hg for systolic blood pressure (SBP) and -0.35 mm Hg for diastolic blood pressure (DBP), but there was no statistical significance. Among women, the pooled estimates of regression coefficients adjusted for age and BMI were -0.92 mm Hg for SBP and -0.83 mm Hg for DBP with statistical significance. After adjustment for age, BMI, alcohol intake and urinary excretion of sodium and potassium, the pooled estimate of calcium intake was -0.66 mm Hg for DBP with statistical significance and -0.70 mm Hg for SBP. A significant negative association of calcium intake with blood pressure was observed among the subjects in Osaka. Our study suggests that increased calcium intake may provide a benefit of lowering blood pressure independently of other minerals such as sodium and potassium.

The relationship between new stroke onset and serum thiocyanate as an indicator to cigarette smoking

The case subjects were 67 stroke patients (27 males and 40 females, mean age 65.7+/-7.1), who suffered from stroke attack and had participated in annual medical check-up between 1987 and 1988 at Oyabe Public Health Center. The controls, which were adjusted for sex, age and blood pressure level with the case subjects, were selected from participants attending their annual medical check-up in 1987-1988. The serum thiocyanate level of case subjects were significantly higher than that of controls (p<0.05). The usefulness of measurement of serum thiocyanate level as an indicator of smoking status was assessed by using multiple logistic regression analysis adjusting for body mass index, mean blood pressure, and serum cholesterol was found. An odds ratio of 3.00 (95% confidence interval: 1.06-8.48, p<0.05) in cerebral infarction. It is considered that serum thiocyanate may be useful as an indicator of smoking status to assess the relationship with stroke onset, especially for cerebral infarction.

Socioeconomic differences in behavioural and biological risk factors: a comparison of a Japanese and an English cohort of employed men

BACKGROUND

To compare socioeconomic differences in behavioural and biological risk factors in Japanese and English 39-59-year-old employed men.

METHODS

We measured systolic and diastolic blood pressure, total and high density lipoprotein (HDL) cholesterol, body mass index (BMI), waist-to-hip ratio and fibrinogen at medical screenings and smoking and alcohol consumption in health questionnaires among Japanese non-manual and manual employees of a steel products company and among English non-manual employees working in Civil Service departments.

RESULTS

In England, higher employment grades were advantaged with regard to most risk factors studied. In Japan the picture was different in that higher grades had higher BMI, waist-to-hip-ratio and lower HDL cholesterol. In Japan employment grade differences in these three risk factors are clearly larger among younger men than among older men, while in England age differentials in the grade differences are small. Similar results were obtained for education.

CONCLUSIONS

Important differences in the social patterning of risk factors were observed in our cohorts of employed Japanese and English men. The contribution that these risk factors make in explaining social differences in health may vary accordingly. Studies that identify the common and unique determinants of socioeconomic health differences in different populations are needed.

Characteristic lifestyles in 6-year-old children with obese parents: Results of the toyama birth cohort study

OBJECTIVE

The aim of this study was to identify characteristic lifestyles in children with obese parents.

METHODS

8,030 children (4,072 males and 3,958 females) aged 6 to 7 years were investigated. A questionnaire relating to the lifestyles of children was distributed through elementary schools for completion by parents. The heights and weights of parents were self-reported. A parent with a body mass index (weight in kilograms divided by the square of height in meters) greater than the 90th percentile for gender (26.7 kg/m(2) for fathers and 24.3 kg/m(2) for mothers) was defined as an obese parent. A chi-square test for each trend was applied to evaluate an increasing trend in the frequency or level of each lifestyle in children with obese parents.

RESULTS

Children with obese parents were significantly associated with increasing trends in the proportions categorized by irregular intake of breakfast, faster eating, longer TV watching, and shorter sleeping hours.

CONCLUSIONS

These lifestyles are considered to be possible risk factors for the development of obesity. These characteristic lifestyles observed in children with obese parents could strengthen the relationship between child and parental body compositions, in addition to the genetic predisposition to obesity in children with obese parents. These findings indicate that education with lifestyle modification for obese parents will be required to prevent further weight gain in children with obese parents.

[Study of remanent magnetization of the human body: lung and liver tissues]

In this study, we used lung and liver tissue specimens distracted from tissue to investigate remanant magnetization, and found that specimens with a volume of 6 mm3 had an intensity of 10(-10) Am2, which was significantly stronger than the noise level of the superconducting magnetometer. This finding indicates that both lung and liver tissues contain magnetic materials. We speculated that biological magnetite is the magnetic material in these tissues. In addition, we found that lung tissue specimens with strong magnetization had correspondingly strong magnetized findings in the liver tissue specimens. In a comparison of magnetization in lung cancer tissue specimens and normal lung tissue, no significant relationship was noted, but two of the lung cancer tissue specimens showed strong magnetization. The number of lung cancer specimens studies was insufficient to investigate the relation between the magnetization (accumulation of magnetic materials) and lung cancer, and further studies are necessary. The magnetic properties of two lung cancer tissue specimens showing strong magnetization were further investigated, and an alternating field demagnetization experiment showed that their magnetization was composed of a unit stable vector, which indicates that the lung tissue may have been magnetized after the accumulation of magnetic materials. The Wohlfarth ratio (Moskowitz et al., 1989) of them was less than 0.5, which suggests that magnetic materials are distributed in clusters in lung tissue.

Birth weight, childhood growth, and cardiovascular disease risk factors in Japanese aged 20 years

To determine whether birth weight and childhood growth, especially rate of height increase, are independently related to major cardiovascular disease risk factors in adult life, the authors conducted a 20-year follow-up study in a Japanese population, using the record-linkage method. From medical checkup data for babies and for residents aged 20 years in Ishikawa, Japan, the authors obtained 20-year follow-up data (1985-1994) on 4,626 participants (2,198 men and 2,428 women) born in 1965-1974. Using multiple linear regression analysis, the authors estimated that a 1-standard-deviation higher birth weight was significantly associated with systolic blood pressure that was lower by 1.6 mmHg in men and by 1.0 mmHg in women, and with a serum cholesterol level that was lower by 0.07 mmol/liter in men and by 0.04 mmol/liter in women, after adjustment for current weight and rate of height increase. Moreover, after adjustment for birth weight and current weight, a 1-standard-deviation higher rate of height increase from age 3 years to age 20 years was significantly associated with systolic blood pressure that was lower by 0.7 mmHg in men and by 0.5 mmHg in women, and with serum cholesterol that was lower by 0.09 mmol/liter in men and by 0.05 mmol/liter in women. The results suggest that lower birth weight and lower rate of height increase during childhood are independently associated with increases in blood pressure and serum cholesterol in adult life.

Bone mineral density of the spine, hip and distal forearm in representative samples of the Japanese female population: Japanese Population-Based Osteoporosis (JPOS) Study

Low bone mineral density (BMD) is one of the most important elements for the diagnosis of osteoporosis and screening people with higher risk of fractures. To establish the criterion value of BMD for the diagnosis of osteoporosis and to estimate the prevalence rate of osteoporosis in Japanese women, we performed a Japanese population-based osteoporosis (JPOS) study. The subjects were 4550 women aged 15 through 79 years randomly selected from seven municipalities throughout Japan. The sample size was determined to ensure that the observed mean BMD would remain within 2.5% from the real value with a probability of 0.95 in each of the 5-year age groups. The study comprised bone mass measurements by dual-energy X-ray absorptiometry at the spine (L2-4), hip and distal forearm, body size measurements and detailed interviews on medical and gynecologic history. After excluding those subjects with apparent or suggested abnormalities affecting bone mass from 3985 women (87.6%) who completed the study, 3465 women remained and served as the subjects. We present 5-year age-specific mean values of BMD and cut-off values for the diagnosis of osteoporosis according to World Health Organization (WHO) and the Japanese Society of Bone and Mineral Research (JSBMR) criteria. The cut-off levels at the spine and the distal radius proposed in this study were similar to those proposed by the JSBMR but the cut-off level at the femoral neck in this study was 4.7% higher than that of the JSBMR. The prevalence rates of osteoporosis according to WHO criteria in the present subjects aged 50 through 79 years were calculated as 38.0% at the spine, 11.6% at the femoral neck and 56.8% at the distal one-third site of the radius, and those in the Japanese female population of the same age were estimated to be 35.1%, 9.4% and 51.2%, respectively. A fivefold difference was observed among the prevalence rates at different skeletal sites, which suggests that the different definitions of osteoporosis should be established for the different skeletal sites. The prevalence rate diagnosed at the femoral neck seemed to be lower in the present study than those reported for Caucasians. This might account for a lower incidence rate of hip fracture in Japanese women.

Trends in stroke incidence and acute case fatality in a Japanese rural area : the Oyabe study

BACKGROUND AND PURPOSE

Stroke mortality in Japan has significantly declined during recent decades. To determine the cause of this decrease, we studied the trends in stroke incidence and case fatality within 28 days after stroke in a rural area in Japan.

METHODS

We used a population-based registry during 1977-1991 in Oyabe, a rural area in the central part of Japan. The average population aged 25 years and older numbered 32 859 persons. Changes in age-standardized stroke incidence rate were calculated and compared between the 3 periods 1977-1981, 1982-1986, and 1987-1991. The 28-day case fatality rate was evaluated and also compared between the 3 periods by onset year.

RESULTS

The total number of strokes was 2068. The age-standardized incidence rate of all strokes decreased during the 15-year period, from 605 to 417 per 100 000 in men and from 476 to 329 per 100 000 in women. A marked decline was found during 1977-1986 but was not apparent during 1987-1991. Moreover, there was an increase in the group aged 75 years and older. The 28-day case fatality rates for all strokes improved from 18.0% to 14.2% in men and from 26.8% to 19.1% in women during the observation period.

CONCLUSIONS

These data indicate that declines in the stroke incidence and the 28- day case fatality have been associated with a marked decrease in stroke-related mortality in Japan.

Reference data of forearm bone mineral density in healthy Japanese male and female subjects in the second decade based on calendar age and puberty onset: Japanese Population Based Osteoporosis (JPOS) study

Osteoporosis is a major public health problem in Japan. The second decade is an important period in which to attain a high peak bone mass. However, normal values of forearm bone mineral density (BMD) are not well known in children and adolescents. BMD at one-third of forearm length proximal to the ulnar end plate (BMD1/3) and the ultradistal forearm (BMDud) was measured using dual-energy X-ray absorptiometry (DXA) in 1207 (631 males, 576 females) Japanese subjects aged 9-18 years. Puberty onset was assessed by questionnaire, by obtaining the time that pubic hair appeared in males and the time that menstruation started in females. BMD1/3 and BMDud increased steadily with age in males. In relation to puberty development, these parameters also increased after puberty onset although the increase in BMD1/3 was not statistically significant after the fifth year from puberty onset and that of BMDud was not significant after the sixth year from puberty onset. BMD1/3 and BMDud increased with age and then plateaued in females. The increase in BMD1/3 was not statistically significant after 15-16 years of age and that of BMDud was not significant after 13-14 years of age. In relation to puberty development, the increase in BMD1/3 leveled out after the fourth year from puberty onset and that of BMDud also plateaued after the third year from puberty onset. We provide reference values of forearm BMD in Japanese children and adolescents by DXA according to calendar age and puberty development. Peak bone mass of the forearm may be in the late second decade in Japanese females.

Trends in blood pressure and urinary sodium and potassium excretion in Japan: reinvestigation in the 8th year after the Intersalt Study

Using the identical protocol of an Intersalt Study previously conducted, we undertook a new study (Intersalt-2) 8 years later. We measured changes in various factors affecting blood pressure (BP) including urinary sodium and potassium excretion in three districts of Japan: Osaka, Tochigi, and Toyama. Also we evaluated the trends in the relationships of those factors to BP. The Intersalt Study revealed that the average sodium excretion of all three study centres was high (particularly in Toyama) while potassium excretion was relatively low. The sodium/potassium ratio was therefore relatively high. The body mass index (BMI) was favourable, but the prevalence of heavy alcohol drinkers was high. Comparing the first to the second study reveals a decrease in sodium excretion in Toyama, although that area still had the highest value of the three study centres. The average potassium excretion increased only in Osaka. Sodium/potassium ratio decreased in all centres. BMI and the prevalence of heavy drinkers among the subjects of both studies were nearly the same. The trend of the relationship of sodium to BP in Osaka changed from negative to positive. In Toyama, it changed from positive to negative. It is thought that this negative relationship might occur in conjunction with a reduction in salt consumption in a population. In conclusion this study reveals that average sodium consumption in Japan remains high while potassium consumption is still low. As a factor in the prevention of hypertension, further efforts to reduce salt consumption and increase potassium intake are still needed.

[Physio-social activities and active life expectancy, life expectancy in Japanese elderly]

PURPOSE

Incidence of loss of activity and death in elderly people living at home were investigated to attempt to determine their relationship to physio-social activities in elderly.

METHOD

This longitudinal study of life expectancy and active life expectancies is a thirty-six months follow up study. Loss of activities were classified as follows: Long term (over six months) treatment at home, long term (over six months) admission to hospital or intermediate institute for the elderly, admission to nursing home, and death. Subjects were persons living at home in Ogi, Saga prefecture, aged 70 years or older not requiring help in active daily living (ambulating, bathing, dressing, discharging, eating).

RESULTS

6,274 (male = 2,383, female = 3,891) subjects were followed for thirty six months, and 178 people experienced long term treatment at home, 310 people had long term admission to a hospital or intermediate institute for elderly, 28 people were admitted to a nursing home and 449 people experienced death. The main results were as follows: (1) From the Cox proportional hazards model using the likelihood-ratio method of survival and active life loss, significant hazard ratios for reduction active life expectancy for male were found for age, disability score for ADL, speech disorder, inconvenient bathroom design, with attention to health, and daily activity were associated with extension of active life expectancy. Age, disability score for ADL, speech disorder, inconvenient bathroom design were associated with reduced life expecting, while, attention to health, choosing to undergo regular health examinations, and daily were associated with increased activity in life expectancy. (2) Hazard ratios for reduction active life expectancy for females were age, disability score for ADL, defect of memory deficits, inconvenient design for hallway and stairs. Participating in health examinations, Purpose in life were associated with life expectancy increase. For females were age, disability score for ADL, speech disorder, inconvenient design of bathroom were associated with decrease in life expectancy, while having a person in life was associated with increase in life expectancy.

DISCUSSION

Relationship between physio-social activities in elderly is a significant factor in many studies on elderly health. This study suggests that age, disability score for ADL, inconvenient for housing design, active health behavior, daily activities, and Losing a sense of worth in living, affect active life expectancy and life expectancy.

The relationship between lifestyle, social characteristics and obesity in 3-year-old Japanese children

It has been observed that obese children receive genetic and environmental effects that are associated with them being overweight. With regard to the latter, lifestyles such as eating habits and physical activity have been focused on. In the present study, the social characteristics which would dominate their lifestyles were investigated as background variables. For this purpose, 9668 Japanese children aged three years who were all born in Toyama prefecture, Japan, in 1998, served as birth cohort subjects. For the comparison between obese (Kaup Index; mass in kg/(height in m)2 > or = 18) and nonobese (Kaup index < 18) children, irregular snack intake, physical inactivity and reduced sleeping hours were chosen as statistically significant obesity-related lifestyle indicators for the children. For social characteristics, family construction (expanded family with grandparents/nonexpanded family), main caregiver (mother/other), attending a nursery school (yes/no) and mother's employment (full-time worker/other) were chosen. These were significantly associated with the obesity-related lifestyles mentioned above using multiple logistic regression analysis adjusted for other variables of social characteristics as well as for gender and birth month (July-December/January-June). The two greatest population-attributable risk percentages were observed for mother as main caregiver (-36.5%) and attending a nursery school (-28.9%) for irregular snack intake. Therefore, these two social characteristics substantially reduced the number of children with irregular snack intake. On the other hand, the two social characteristics were reversed in children with reduced sleeping hours (population-attributable risk percentage of mother as main caregiver: 15.4%; attending a nursery school: 17%). In contrast with favourable effects on snack intake these social characteristics showed an adverse influence on the sleeping habits of children.

Influence factors on the development of obesity in 3-year-old children based on the Toyama study

BACKGROUND

Obesity in childhood increases the risk of obesity in adulthood. Obesity in adulthood is a risk factor for chronic diseases such as hypertension and atherosclerosis. Therefore, it is important to eliminate factors influencing the development of obesity in children from the viewpoint of preventive medicine. The purpose of this study is to elucidate the relationship between obesity and lifestyle in 3-year-old children in a case-control study.

METHODS

Subjects were selected from the Toyama study at health checkups for 3-year-old children which are done routinely by local governments in Japan on all children of that age. A special questionnaire consisting of items on lifestyle and environmental factors of the children and past histories of parents was distributed to the Toyama study participants beforehand and was collected at the checkup. Matched-pair comparisons were performed between obese children whose body mass index was 18 or more (N = 427) and control children (N = 854) matched by sex and birth month. Multivariate stepwise conditional logistic regression analysis was also applied to assess the influence of confounding factors.

RESULTS

The following six factors significantly influenced the development of obese 3-year-old children using the Mantel-Haenszel method: the mother's job, limited playtime outdoors (1 hour or less), snacking irregularity, an overweight father (body mass index >/= 24), an overweight mother (body mass index >/= 24), and overweight at birth (birth weight >/= 3,500 g). An overweight mother or father, limited playtime outdoors, overweight at birth, and snacking irregularity were significantly related to obesity in 3-year-old children after adjusting for confounding factors by multivariate stepwise conditional logistic regression analysis.

CONCLUSIONS

We have suggested several factors influencing the development of obesity in 3-year-old Japanese children: parental overweight and overweight at birth as host factors, physical inactivity and snacking irregularity as behavioral factors, the mother's job as an environmental factor.

[Follow-up study on effects of height velocity and puberty onset on biochemical markers of bone turnover]

In order to clarify the factors which affect bone metabolism at a young age, we investigated the relationships among the change of biochemical markers of bone turnover, the height velocity (HV) and puberty onset in healthy Japanese children. One hundred and twelve children (61 boys and 51 girls) were recruited at the fourth grade level in the elementary school (9 years old) and followed for 6 years. Serum bone specific alkaline phosphatase (B-ALP), serum tartrate-resistant acid phosphatase (TR-ACP), urine hydroxyproline (Hyp) and urine calcium (Ca) were measured as the biochemical markers of bone turnover. Bone mineral density of calcaneus was also measured by ultrasound method at the first grade (12 years old) and the third grade (14 years old) of junior high school. Heights and weights of all subjects were measured every April and the HV were calculated between each year. Puberty onset was defined as the time when pubic hair appeared in boys and as the time when menarche started in girls by self-administered questionnaire. All the biochemical markers of bone metabolism except for urine Ca had a significant positive relationship with HV. The values of the markers were highest of the time when the HV was maximum. In girls, the values of the biochemical markers remained high before menarche and then decreased significantly within three years after menarche, suggesting that bone turnover changed rapidly from high turnover type to low turnover type after menarche. On the other hand, in boys, high turnover type remained for a few years after puberty onset. Bone mineral density of calcaneus by ultrasound method increased significantly in boys between the two years in junior high school, but the increase was unclear except for broadband ultrasound attenuation (BUA) in girls in the same period.

Relationship between the level of activities of daily living and chronic medical conditions among the elderly

The purpose of this study is to observe the disease-disability association through a cross-sectional study. Between 1994 and 1995, we conducted a questionnaire survey in 5 towns in Japan. Among the items included in the questionnaire, 5 related to ADL (bathing, feeding, dressing/undressing, toileting, and going out socially) were treated as purpose variables; and 5 related to the history of medical treatment received over the past year (diabetes, heart disease, cerebrovascular disease, neuralgia, and bone fractures) were used as explanatory variables. Multiple logistic models were applied to observe the relationship. The history of medical treatment for cerebrovascular disease greatly and unavoidably affects disability related to ADL. Bone fractures, diabetes, and heart diseases contributed to specific ADL disabilities.

[Active life expectancy, life expectancy and ADL in Japanese elderly]

The purpose of the present Study is to analyze the incidence of loss of active life and death rates over a 36 month period in elderly people living a home, to attempt to determine relationships of index of ADL for bed ridden elderly to incidence and expectancies of active life loss, for life and active life. The definition of loss of activities was as follows: Long term (over six months) medication at home, long term (over six months) admission to hospital or intermediate institute for elderly, admission to nursing home or death. Subjects were 6,883 people living at home in Ogi, Sage prefecture, aged 70 years or older. A total of 6,753 people could be followed up for thirty six months, with 287 people having long term medication at home, 389 people having long term admission in hospital or intermediate institute for elderly, 45 people were admission to nursing home and of these groups defined as experiencing, 490 people were died of all subjects, 746 deaths were observed. The main results were as follows: (1) Annual mortality rate was 5.4% for males, 3.0% for females, and annual rate of active life loss was 7.1% for males, 6.0% for females. Life expectancy for the 70-74 year group was 13.7 years for male, 17.9 years for female, and active life expectancy for the 70-74 year group was 12.0 year for males, 13.9 years for females. The difference between life expectancy and active life expectancy was 1.7 years for male, 4.2 years for female, which can be considered the average length of term requiring care. (2) From the relation between scale of active daily living for the handicapped elderly and the life expectancies of life and active life by Cox proportional hazard model analysis of survival, controlling for age and sex, five categories of classification for active daily living for a handicapped elderly were developed: 1-very healthy with abilities for using transportation (train and bus); 2-abilities of moving in the neighborhood by oneself; 3-abilities of moving in the neighborhood with help; 4-Chair-bound, 5-Bed-bound.

Working hours as a risk factor for acute myocardial infarction in Japan: case-control study

OBJECTIVE

To clarify the extent to which working hours affect the risk of acute myocardial infarction, independent of established risk factors and occupational conditions.

DESIGN

Case-control study.

SETTING

University and general hospitals and routine medical examinations at workplaces in Japan.

SUBJECTS

Cases were 195 men aged 30-69 years admitted to hospital with acute myocardial infarction during 1990-3. Controls were 331 men matched at group level for age and occupation who were judged to be free of coronary heart diseases at routine medical examinations in the workplace.

MAIN OUTCOME MEASURES

Odds ratios for myocardial infarction in relation to previous mean daily working hours in a month and changes in mean working hours during previous year.

RESULTS

Compared with men with mean working hours of >7-9 hours, the odds ratio of acute myocardial infarction (adjusted for age and occupation) for men with working hours of >11 hours was 2.44 (95% confidence interval 1.26 to 4.73) and for men with working hours of <=7 hours was 3.07 (1.77 to 5.32). Compared with men who experienced an increase of <=1 hour in mean working hours, the adjusted odds ratio of myocardial infarction for men who experienced an increase of >3 hours was 2.53 (1.34 to 4. 77). No appreciable change was observed when odds ratios were adjusted for established and psychosocial risk factors for myocardial infarction.

CONCLUSION

There was a U shaped relation between the mean working hours and the risk of acute myocardial infarction. There also seemed to be a trend for the risk of infarction to increase with greater increases in mean working hours.

[Studies on carcinogenicity of asbestos with special reference to interaction between viruses and cultured cells]

To investigate effects of asbestos on the process of cancer development, the capacity of asbestos which increases cellular uptake of external carcinogens was tested for asbestos-mediated viral RNA transfection in cultured cells. For the transfection, crocidolite, amosite, anthophyllite and chrysotile were placed onto Vero-E6 cells with poliovirus RNA inoculum, respectively. All asbestos samples mediated viral RNA transfection compared with the background including only viral RNA. The transfection was much greater with combined exposure to asbestos and kaolin than with exposure to asbestos alone.