Masayuki Iki

Kinki University, Ōsaka-shi, Osaka-fu, Japan

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Publications (111)327.25 Total impact

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    ABSTRACT: Abstract Context: Although there is a positive relationship between height and blood pressure (BP) levels in children, there are no reports regarding the association between height and BP levels in adolescents and adults. Objective: This study examined whether there is an association between height and BP levels in Japanese adolescents. Methods: The source population was all fifth (10 and 11-year-olds) and ninth graders (14 and 15-year-olds) who attended 11 elementary schools and five junior high schools in the Iwata area from 2002-2008. School-based screenings were conducted annually by the local government from April to June. Data obtained from health examinations were analysed, including anthropometric measurements and BP levels, for 11 780 children (98.7% of the source population). Results: Height showed significant positive relationships with systolic blood pressure (SBP) and diastolic blood pressure (DBP) in childhood and in adolescent males. In contrast, the relationship between height and SBP was significantly weaker in adolescent females than in childhood and there was no significant relationship between height and DBP in adolescent females. Conclusion: The relationship between height and SBP was attenuated by development in females and the relationship between height and DBP disappeared.
    Annals of Human Biology 08/2013; · 1.48 Impact Factor
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    ABSTRACT: Bone strength is predominantly determined by bone density, but bone microarchitecture also plays an important role. We examined whether trabecular bone score (TBS) predicts the risk of vertebral fractures in a Japanese female cohort. Of 1950 randomly selected women aged 15-79 years, we analyzed data from 665 women aged 50 years and older, who completed the baseline study and at least one follow-up survey over 10 years, and who had no conditions affecting bone metabolism. Each survey included spinal imaging by X-ray absorptiometry for vertebral fracture assessment and spine areal bone mineral density (aBMD) measurement. TBS was obtained from spine DXA scans archived in the baseline study. Incident vertebral fracture was determined when vertebral height was reduced by 20% or more and satisfied McCloskey-Kanis criteria or Genant's grade 2 fracture at follow-up. Among eligible women (mean age, 64.1 ± 8.1 years), 92 suffered incident vertebral fractures (16.7/10(3) person-years). These women were older with lower aBMD and TBS values relative to those without fractures. The unadjusted odds ratio of vertebral fractures for one standard deviation decrease in TBS was 1.98 (95% confidence interval (CI): 1.56, 2.51) and remained significant (1.64, 95% CI:1.25, 2.15) after adjusting for aBMD. The area under the receiver operating characteristic curve of TBS and aBMD combined was 0.700 for vertebral fracture prediction and was not significantly greater than that of aBMD alone (0.673). However, reclassification improvement measures indicated that TBS and aBMD combined significantly improved risk prediction accuracy compared with aBMD alone. Further inclusion of age and prevalent vertebral deformity in the model improved vertebral fracture prediction, and TBS remained significant in the model. Thus, lower TBS was associated with higher risk of vertebral fracture over 10 years independently of aBMD and clinical risk factors including prevalent vertebral deformity. TBS could effectively improve fracture risk assessment in clinical settings.
    Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research 07/2013; · 6.04 Impact Factor
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    ABSTRACT: For a general population of children, data on the relationship between vitamin D status and adiposity are limited. The aim of this study was to assess the relationships between the serum concentration of 25-hydroxyvitamin D (25-OH-D) and body fat variables measured by dual-energy X-ray absorptiometry (DXA) in a general population of Japanese children, including underweight, normal, and overweight children. The source population comprised 521 fifth-grade children who attended either of the two public schools in Hamamatsu, Japan. Total and regional body fat mass (FM) measured by DXA were evaluated along with the serum concentration of 25-OH-D. We were able to analyze the FM and 25-OH-D data of 400 of the 521 children. Among boys, significant inverse relationships were observed between serum vitamin D levels and body fat variables (total FM, r = -0.201; trunk FM, r = -0.216; appendicular FM, r = -0.187; P < 0.05 for all values). Mean values of total FM and trunk FM in the vitamin D-deficient group (25-OH-D <50 nmol/L) were larger than those in the vitamin D-sufficient group (25-OH-D ≥75 nmol/L) after adjusting for confounding factors, such as sedentary behavior (P < 0.05). No relationship was observed between vitamin D status and FM among girls. Vitamin D deficiency was associated with higher total and trunk adiposities in a general population of Japanese children, particularly boys.
    Nutrition 06/2013; · 2.86 Impact Factor
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    ABSTRACT: End-stage renal failure deteriorates bone mass and increases fracture risk. However, there are conflicting reports in the literature regarding the effects of mild to moderate renal dysfunction on bone mineral density (BMD). We investigated the association between renal function and BMD at the spine and hip and bone metabolism markers in community-dwelling elderly Japanese men. From 2174 male volunteers aged ≥65years, we examined 1477 men after excluding those with diseases or medications known to affect bone metabolism. Renal function was assessed by serum cystatin C and estimated glomerular filtration rate (eGFR) calculated using the Modification of Diet in Renal Disease study equation. Bone metabolism was evaluated using levels of serum amino-terminal propeptide of type I procollagen (PINP) and tartrate-resistant acid phosphatase isoenzyme 5b (TRACP-5b), which represent bone metabolic status independently of renal function. eGFR was inversely associated with BMD after adjusting for potential confounders (P<0.01). Cystatin C showed a weaker but significant association with BMD. eGFR was modestly positively associated with PINP levels (P=0.04), although cystatin C concentrations were neither associated with PINP nor TRACP-5b levels. Since BMD integrates bone metabolism from the past to present, inverse associations between renal function and BMD may be attributed to past factors, such as obesity. Our findings suggest that low renal function does not affect bone metabolism in a population of community-dwelling elderly Japanese men. Longitudinal studies will be necessary to clarify whether low renal function affects bone loss.
    Bone 05/2013; · 3.82 Impact Factor
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    ABSTRACT: OBJECTIVE: Metabolic syndrome contains many risks for medical diseases such as cardiovascular disease and diabetes, which might precipitate depressive symptoms in the older people. However, the association between depressive symptoms and metabolic syndrome in Japanese community-dwelling older people is unclear. This study was performed to answer this important question. METHODS: Cross-sectional analyses were performed on 3796 community-dwelling independent older people (≥65 years, 1911 men and 1885 women) from the 2007-2008 baseline examination of the Fujiwara-kyo study, a prospective cohort study on successful aging. Depressive symptoms were assessed using the 15-item short form of the Geriatric Depression Scale and metabolic syndrome was defined according to the 2005 International Diabetes Federation. Covariates were social supports, negative life events, health behavior, education, cognitive function, anthropometric status, and others. Multiple logistic regression analyses were performed to determine the relationships between depressive symptoms and these variables. RESULTS: The prevalence of depressive symptoms (Geriatric Depression Scale-15 ≥6) and metabolic syndrome were 14.8% and 16.6%, respectively. Significant protective factors against depressive symptoms were higher education, more opportunity for drinking of alcohol, better social supports, and more walking daily. Metabolic syndrome was statistically associated with depressive symptoms (adjusted odds ratio = 1.32, 95% confidence interval = 1.03-1.68). Other risk factors significantly associated with depressive symptoms were sleep disturbance, visual or hearing impairment, and negative life events. CONCLUSIONS: The present study showed an association between metabolic syndrome and depressive symptoms in ambulatory Japanese older people, as in western countries.
    International Journal of Geriatric Psychiatry 03/2013; · 2.98 Impact Factor
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    ABSTRACT: Background: Because of the lack of relevant data, we investigated the association between rapid weight gain (RWG) during early childhood and cardiovascular risk factors in Japanese adolescents.Methods: The source population comprised 2285 adolescents aged 13 to 14 years enrolled in any public school in Fukuroi City, Japan during 2008, 2009, or 2010. Since there are no private schools in this city, almost all adolescents who lived in the city went to 1 of these schools. We obtained data on blood pressure (BP), serum lipids, and anthropometry during adolescence, as well as anthropometry at birth, age 1.5 years, and age 3 years, from the Maternal and Child Health Handbook for 1624 children. RWG was defined as a change in body-weight standard deviation score greater than 0.67 from age 0 to 1.5 years or from age 1.5 to 3 years.Results: After adjusting for confounding factors, adolescents who had RWG from 0 to age 1.5 years or from age 1.5 to 3 years were more likely to be overweight. Adolescents who had RWG during both periods were more likely to be overweight (odds ratio [OR], 6.37; 95% CI, 3.06-13.24), have unfavorable lipid concentrations (OR, 2.03; 95% CI, 1.15-3.58), and have high BP (OR: 2.36, 95% CI: 1.34-4.13). The associations with unfavorable lipid concentrations and high BP disappeared after further adjusting for current body mass index.Conclusions: RWG during early childhood predicts unfavorable lipid concentrations and high BP in Japanese adolescents, and this relationship is mediated by body mass index in later life.
    Journal of Epidemiology 12/2012; · 2.11 Impact Factor
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    ABSTRACT: Background: Body fat distribution is defined as the pattern of fat deposits in different regions of the body and usually expressed as a ratio. There are few studies on the relationship between blood pressure and the ratio of central fat measured on dual-energy X-ray absorptiometry (DXA) in childhood. Methods and Results: The source population consisted of 521 fifth-grade children who attended elementary school in Hamamatsu, Japan, with 401 (77.0%) included in the study. Regional fat was determined using a DXA scanner in a mobile test room. The ratio of trunk to appendicular fat was calculated as trunk fat mass divided by appendicular (arms and legs) fat mass. In boys, the trunk-to-appendicular fat ratio was significantly related to systolic blood pressure and diastolic blood pressure after adjusting for confounding factors such as height and pubic hair appearance. In addition, an increase in trunk-to-appendicular fat ratio was related to an increase in blood pressure after adjusting for confounding factors including whole body fat volume and trunk fat volume. The relationship between fat distribution and blood pressure was not observed in girls. Conclusions: An excessive proportion of trunk fat was related to increased blood pressure in the boys in a general population of Japanese children. The relationship between fat distribution and blood pressure was independent of the relationship between fat volume and blood pressure.
    Circulation Journal 08/2012; · 3.58 Impact Factor
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    ABSTRACT: 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.
    Osteoporosis International 08/2012; · 4.04 Impact Factor
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    ABSTRACT: Screening for low bone mass is important to prevent fragility fractures in men as well as women, although men show a much lower prevalence of osteoporosis than women. The purpose of this study was to establish a screening model for low bone mineral density (BMD) using a quantitative ultrasound parameter and easily obtained objective indices for elderly Japanese men. We examined 1633 men (65-84 yr old) who were subjects of the Fujiwara-Kyo Study. Speed of sound (SOS) at the calcaneus was determined, and BMD was measured by dual-energy X-ray absorptiometry at the lumbar spine (LS), total hip (TH), and femoral neck (FN). Low BMD was defined as >1 standard deviation below the young adult mean, in accordance with World Health Organization criteria. We performed receiver operating characteristic (ROC) analysis to identify a better screening model incorporating SOS and determined the optimal cutoff value using Youden index. Prevalences of low BMD at the 3 skeletal sites were 27.8% (LS), 33.5% (TH), 48.6% (FN), and 43.3% at either LS or TH. The greatest area under the ROC curve (0.806, 95% confidence interval: 0.785-0.828) and smallest Akaike's information criterion were obtained in the multivariate model incorporating SOS, age, height, and weight for predicting low BMD at all skeletal sites. This model predicted low BMD at TH with the sensitivity of 0.726 and specificity of 0.739, whereas a similar model predicted low BMD at LS with much lower validity. We conclude that the multivariate model for TH could be used to screen for low BMD in elderly Japanese men.
    Journal of Clinical Densitometry 06/2012; 15(3):343-50. · 1.71 Impact Factor
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    ABSTRACT: Background: A few studies reported an association between body weight during early childhood and body composition in later life, as measured by dual-energy X-ray absorptiometry (DXA); however, none of those studies investigated an East Asian population. In a Japanese population, we examined the association between body weight at age 3 years and body composition at age 11 years, as measured using DXA.Methods: The source population was 726 fifth-grade school children enrolled at 3 public schools in Shizuoka Prefecture, Japan from 2008-2010. All children who lived in the study area went to 1 of these 3 schools. DXA was used to obtain data on body composition, and the Maternal and Child Health Handbook was used to calculate body mass index (BMI). The general linear model was used for statistical analysis.Results: We were able to analyze data on body composition at age 11 years and BMI in early childhood for 550 children. BMI at age 3 and change in BMI z-score from birth to age 3 were positively associated with bone mineral content (BMC), fat-free soft tissue mass (FFSTM), and fat mass (FM) at age 11. After adjusting for confounding factors, mean BMC, FFSTM, and FM were significantly lower among children who were underweight at age 3 and significantly higher among children who were overweight at age 3, as compared with values for normal-weight children at age 3.Conclusions: Among Japanese children, body weight at age 3 years predicts body composition at age 11 years.
    Journal of Epidemiology 06/2012; 22(5):411-6. · 2.11 Impact Factor
  • Masayuki Iki
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    ABSTRACT: The high prevalence and tragic consequences of related fractures make osteoporosis a major burden on modern society. According to population-based epidemiologic studies, the estimated number of people with osteoporosis in Japan is 15 million, and only 20% of them are under treatment. Osteoporosis is a highly undertreated disease. The most recent incidence rates of hip fracture in Japan were 5.1 in 10,000 men and 18.1 in 10,000 women in 2007, and the number of patients are approximately 130 thousands which are 2.8-fold higher than those of the initial survey of 1987, but are still substantially less than rates in Caucasian populations. This increase in incidence rates can be explained by an increase in the elderly population. Data on the prevalence and incidence of vertebral fractures in Japan are vague compared with those of hip fracture. Prevalence rate of vertebral fracture was reported to be comparable to those in Caucasian populations, or even higher, and is approximately 30% in women aged 70s and 40% in those aged 80s. Hip fracture increases the mortality risk by approximately 10% or 20% during one year after the index fracture. Functional level of patients with hip fracture is deteriorated in 60% of them compared with pre-fracture level. Vertebral fracture also increases the risk of mortality even in radiographically determined ones. We currently have 13 million patients with osteoporosis in Japan among whom 130 thousands are suffered from hip fracture every year among whom 20 thousands die and 60 thousands experience functional decline. Effective preventive and therapeutic measures for osteoporosis should be conducted in more efficient ways. A greater role of the new guideline is expected than ever to promote preventive measures against osteoporosis and to increase physician's awareness to this disease.
    Clinical calcium 06/2012; 22(6):797-803.
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    ABSTRACT: Current health education programs for osteoporosis prevention are not strictly evidence-based. We assessed whether distribution of an evidence-based guideline improved such programs at municipal health centers. This randomized controlled trial evaluated 100 municipal health centers throughout Japan that were randomly selected from those that planned to revise osteoporosis prevention programs. The implementation status of educational items recommended by the guideline was assessed before and after the intervention by evaluators blinded to the allocation. After the pre-intervention assessment, centers were randomly allocated in a 1:1 ratio to intervention and control groups by a minimization method defining region and city/town as stratification factors. Centers in the intervention group were given copies of the guideline; centers in the control group were instructed to use any information except the guideline. Analyses were performed on an intention-to-treat basis. The guideline was used by 50% of the intervention group. Before the intervention, there was no significant difference in the evidence-based status of health education between the groups. The post-intervention assessment showed that the implementation rates of health education on dietary calcium intake for postmenopausal women and exercise for elderly persons were higher in the intervention group. Specific advice on intakes of calcium and vitamin D and exercise became more evidence-based in the intervention group. The findings suggest that the guideline helped healthcare professionals to improve health education programs by making them more evidence-based. However, the improvements seemed to be limited to items that the professionals felt prepared to improve.
    Journal of Epidemiology 12/2011; 22(2):103-12. · 2.11 Impact Factor
  • Masayuki Iki
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    ABSTRACT: Burden of osteoporosis in men on our society is increasing with aging in population. Prevalence of osteoporosis and incidence of osteoporotic fracture are less frequent in men than in women since bone mineral density is higher, bone size is greater, and hence the bone is stronger in men than in women. In spite of these facts, the number of male patients with osteoporosis was projected to be 3 million in 2005 and is increasing thereafter. Hip fracture was estimated to occur in 33,100 men in 2007 and is increasing as well. Once a man suffers from hip fracture, prognosis is worse in men than in women. However, screening methods for osteoporosis in men are not established, and this causes delay in diagnosis and treatment. Further studies are necessary to answer whether the current young adult value of bone density necessary for diagnosis is appropriate, whether therapeutic regimens are effective in men, whether the cost for diagnosis and treatment is comparable to benefit, whether a valid screening method for osteoporosis in men exists, and whether the screening method is cost-effective.
    Clinical calcium 09/2011; 21(9):1377-83.
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    ABSTRACT: 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. 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. 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. 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. Maintaining weight may help retain hip geometric strength and reduce the risk of hip fracture.
    Osteoporosis International 08/2011; 23(5):1581-91. · 4.04 Impact Factor
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    ABSTRACT: There are no data concerning a relationship between alcohol and bone status from a large-scale community-based study of elderly Japanese men. The baseline survey for the Fujiwara-kyo Osteoporosis Risk in Men Study was performed in 2174 male participants during the period from 2007 to 2008 in Nara Prefecture, Japan. Among them 1665 fitted the following inclusion criteria: (a) age ≥65years, (b) no diseases or drug therapy that could affect bone mineral density (BMD). We analyzed 1421 men with complete information about alcohol intake. We found that alcohol intake and BMD were positively correlated after adjustment for age, body mass index, natto intake, milk intake, smoking, physical activity, education, marital status, and hypertension. Adjusted total hip BMD of men with alcohol intake >39g/day was 0.90g/cm(2) and that of abstainers was 0.85g/cm(2). With regard to bone turnover markers, alcohol intake was inversely associated with serum levels of osteocalcin and tartrate-resistant acid phosphatase isoenzyme 5b. A two-piece linear regression model revealed a positive relationship between alcohol intake and crude mean BMD for the total hip in those with alcohol intake of less than 55g/day. In contrast, alcohol intake and BMD in those with an alcohol intake of 55g/day or more was inversely correlated. The present large-scale study of elderly Japanese men revealed that although an alcohol intake of <55g/day was positively correlated to BMD, alcohol intake of ≥55g/day was inversely correlated to BMD.
    Bone 08/2011; 49(2):275-80. · 3.82 Impact Factor
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    ABSTRACT: The effect of recovery from obesity on cardiovascular risk factors is not well understood in Japanese children. We analyzed follow-up data from the Iwata city population-based study of schoolchildren in Japan. The Iwata Board of Education conducted health screenings of children aged 10 and 14 years. A total of 914 children aged 10 years (451 boys and 463 girls, 87.1% of all children in the city in 1997) were followed until 14 years of age and classified by pattern of obesity as Normal, Recovered, Worsened, or Persistent. Of the 914 children, 111 (12%) were obese at 10 years of age. Of those children, 44 (40%) were no longer obese at 14 years (ie, Recovered). At follow-up, Recovered boys had the greatest decrease in non-HDL cholesterol (mean ± SE, -21.3 ± 3.6 mg/dL) among the 4 groups, and Recovered girls had a significantly lower level of non-HDL cholesterol (Recovered, 107.1 ± 5.4 mg/dL vs. Persistent, 126.1 ± 4.5 mg/dL). The Recovered boys also had a significantly higher level of HDL cholesterol at age 14 (Recovered, 67.2 ± 2.7 mg/dL vs. Persistent, 53.3 ± 2.1 mg/dL). In the Recovered group, 68% of children who were dyslipidemic at baseline had normal cholesterol levels at age 14. The recovery rate from dyslipidemia was significantly higher in the Recovered group (cumulative incidence rate ratio, 2.5; 95% confidence interval, 1.4-4.7) as compared with the Persistent group. Dyslipidemia was reversed in children who recovered from obesity. Our findings suggest that reducing obesity is beneficial to the health of Japanese schoolchildren.
    Journal of Epidemiology 07/2011; 21(5):370-5. · 2.11 Impact Factor
  • Osteoporosis International 06/2011; · 4.04 Impact Factor
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    ABSTRACT: Trends in the prevalence rates of allergic symptoms in children have been discussed extensively, but it remains uncertain which symptoms increase or decrease over time owing to the lack of large-scale long-term consecutive cross-sectional studies performed on a representative population of children. To clarify the trends in the prevalence rates of allergic symptoms in Japanese children. Total population questionnaire surveys were conducted 15 times from 1975 to 2006 for all children attending public elementary schools in Osaka Prefecture, Japan, with the number of subjects ranging from 460,000 to 900,000. Parents of the children completed the questionnaire about allergic symptoms and other symptoms, including wheeze, physician-diagnosed atopic dermatitis, rhinitis, and itching eyes. Response rates were consistently over 90%. The prevalence of wheezing was constant until 1983, then increased from 1983 until 1993, then stabilized at about 4.4%. The lifetime prevalence of atopic dermatitis increased to 24% by 1993, and then decreased. The prevalence of rhinitis increased to 25% by 2003, whereas the prevalence of non-seasonal symptoms plateaued from 1993 on at 11% and vernal symptoms increased. The prevalence of itching eyes continued to increase to 21% in 2006, and vernal symptoms increased sharply. In Osaka Prefecture, Japan, the turning point when the prevalence of wheezing in schoolchildren had begun to increase was 1983. And the turning point when the increase in the prevalence of wheezing, atopic dermatitis, and non-seasonal allergic rhinitis turned to decrease or constant was 1993. The prevalence of rhinitis and itching eyes in spring was still increasing in 2006.
    Pediatric Allergy and Immunology 04/2011; 22(6):631-7. · 3.38 Impact Factor
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    ABSTRACT: Recent animal studies have demonstrated that undercarboxylated osteocalcin upregulates insulin secretion via osteoblast-insulin signaling. However, it remains unclear whether such a pathway exists in humans. This study showed that serum undercarboxylated osteocalcin levels were inversely associated with fasting plasma glucose, hemoglobin A(1c), and homeostasis model assessment of insulin resistance (HOMA-IR) levels in community-dwelling elderly Japanese men. Undercarboxylated osteocalcin (ucOC) was reported to increase insulin secretion and improve glucose tolerance via osteoblast-insulin signaling in animal-based studies. Whether this pathway also exists in humans is unknown. We aimed to clarify whether serum ucOC levels are associated with glycemic status and insulin resistance in the general Japanese population. We included 2,174 Japanese men (≥65 years) who were able to walk without aid from others and lived at home in four cities of Nara Prefecture. We excluded participants with a history of diseases or medications that affect bone metabolism, other than type 2 diabetes mellitus (T2DM). Fasting plasma glucose, glycated hemoglobin A(1c), and HOMA-IR levels were determined as outcome measures. Of the 1,597 participants included in the analysis, both intact OC (iOC) and ucOC levels showed significant inverse correlations with all outcome measures, even after adjusting for potential confounders. Mean values of outcome measures showed a significant decreasing trend with higher quintiles of iOC or ucOC after adjusting for confounders. This trend remained significant for ucOC quintiles after further adjustment for iOC levels, but was not significant for iOC quintiles after adjusting for ucOC levels. These results were attenuated, but still apparent, after excluding participants receiving drug therapy for T2DM. Levels of ucOC, but not iOC, were inversely associated with glycemic index and insulin resistance in a population of Japanese men. These findings will need to be confirmed with longitudinal studies.
    Osteoporosis International 03/2011; 23(2):761-70. · 4.04 Impact Factor
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    ABSTRACT: A cross-sectional analysis of 1,662 community dwelling elderly Japanese men suggested that habitual natto intake was significantly associated with higher bone mineral density (BMD). When adjustment was made for undercarboxylated osteocalcin levels, this association was insignificant, showing the natto-bone association to be primarily mediated by vitamin K. Low vitamin K intake is associated with an increased risk of hip fracture, but reports have been inconsistent on its effect on BMD. Our first aim was to examine the association between BMD and intake of fermented soybeans, natto, which contain vitamin K1 (20 μg/pack) and K2 (380 μg/pack). Our second aim was to examine the association between undercarboxylated osteocalcin (ucOC), a biomarker of vitamin K intake, and BMD to evaluate the role of vitamin K in this association. Of the Japanese men aged ≥65 years who participated in the baseline survey of the Fujiwara-kyo Osteoporosis Risk in Men study, 1,662 men without diseases or medications known to affect bone metabolism were examined for associations between self-reported natto intake or serum ucOC levels with lumbar spine or hip BMD. The subjects with greater intake of natto showed significantly lower level of serum ucOC. Analysis after adjustment for confounding variables showed an association of greater intake of natto with both significantly higher BMD and lower risk of low BMD (T-score < -1 SD) at the total hip and femoral neck. This association became insignificant after further adjustment for ucOC level. Habitual intake of natto was associated with a beneficial effect on bone health in elderly men, and this association is primarily due to vitamin K content of natto, although the lack of information on dietary nutrient intake, including vitamin K1 and K2, prevented us from further examining the association.
    Osteoporosis International 03/2011; 23(2):705-14. · 4.04 Impact Factor

Publication Stats

718 Citations
327.25 Total Impact Points


  • 1998–2013
    • Kinki University
      • • Faculty of Medicine
      • • Department of Mental Health
      Ōsaka-shi, Osaka-fu, Japan
    • Toyama University
      Тояма, Toyama, Japan
  • 1983–2013
    • Nara Medical University
      • Department of Public Health, Health Management and Policy
      Kashihara, Nara, Japan
  • 2012
    • Kio University
      Ōsaka, Ōsaka, Japan
  • 2006
    • Niigata University
      • Department of Environmental and Social Medicine
      Niahi-niigata, Niigata, Japan
  • 2005
    • Tenshi College
      Sapporo, Hokkaidō, Japan
  • 2003–2004
    • Fukuoka University
      • Department of Public Health
      Fukuoka-shi, Fukuoka-ken, Japan
  • 1995–2003
    • Toyama Medical and Pharmaceutical University
      Тояма, Toyama, Japan