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.

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.

Incident fracture associated with increased risk of mortality even after adjusting for frailty status in elderly Japanese men: the Fujiwara-kyo Osteoporosis Risk in Men (FORMEN) Cohort Study.

Frail elderly individuals have elevated risks of both fracture and mortality. We found that incident fractures were associated with an increased risk of death even after adjusting for pre-fracture frailty status as represented by physical performance tests and laboratory tests for common geriatric diseases in community-dwelling elderly Japanese men. INTRODUCTION: While fractures reportedly increase the risk of mortality, frailty may complicate this association, generating a false-positive result. We evaluated this association after adjusting for pre-fracture levels of frailty. METHODS: We examined 1998 community-dwelling ambulatory men aged ≥65 years at baseline in the Fujiwara-kyo Osteoporosis Risk in Men Study for frailty status as represented by activities of daily living (ADL), physical performance tests (grip strength, one-foot standing balance with eyes open, timed 10-m walk), and laboratory sera tests. Participants were then followed for 5 years for incident clinical fractures and death. Effects of incident fracture on death were determined by Cox proportional hazards model with the first fracture during follow-up as a time-dependent predictor and with frailty status indices as covariates. RESULTS: We identified 111 fractures in 99 men and 138 deaths during the follow-up period (median follow-up, 4.5 years). Participants with incident fractures did not have significantly worse frailty statuses, but did show a significantly higher cumulative mortality rate than those without fractures (p = 0.0047). Age-adjusted hazard ratio (HR) of death for incident fracture was 3.57 (95 % confidence interval: 2.05, 6.24). When adjusted for physical performance, this decreased to 2.77 (1.51, 5.06), but remained significant. The HR showed no significant change when adjusted for laboratory test results (3.96 (2.26, 6.94)). Exclusion of deaths within the first 24 months of follow-up did not alter these results. CONCLUSION: Incident clinical fracture was associated with an elevated risk of death independently of pre-fracture levels of frailty in community-dwelling elderly men.

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

UNLABELLED: 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.

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

UNLABELLED: 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.

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.

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

UNLABELLED: 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.

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.

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'.

Greater trunk muscle torque reduces postmenopausal bone loss at the spine independently of age, body size, and vitamin D receptor genotype in Japanese women.

Bone mineral density (BMD) is affected by muscle strength. Recently, vitamin D receptor (VDR) genotype was reported to affect muscle strength as well as BMD in Caucasian women. The aim of this study was to evaluate independent effects of muscle strength of the trunk on BMD at the spine and its change over time in Japanese women. We followed 119 healthy postmenopausal women for 4 years and determined the change in BMD at the spine by dual energy X-ray absorptiometry. Isometric peak torque and isokinetic concentric and eccentric peak torque of the trunk flexors and extensors were measured. The VDR genotype was determined by the PCR-RFLP method based on Apa I and Taq I endonuclease digestions defining the absence/existence of the restriction sites as A/a and T/t, respectively. The subjects were 60.1 +/- 6.6 years old, had 0.808 +/- 0.159 g/cm2 of BMD at baseline. The mean annual change in BMD (delta BMD) was -5.6 +/- 10.4 mg/cm2 during the follow-up period. The VDR genotype, defined by Taq I enzyme, significantly related to BMD at baseline and delta BMD showing that the subjects with genotype TT had the lowest BMD at baseline and lost bone most rapidly. However, its effect on muscle strength was not significant. All the trunk muscle strength indices showed significant positive effects on delta BMD, that is, the effects in increasing the gain and reducing the loss of BMD, after controlling for the effects of age, body size and the VDR genotype. The eccentric trunk extensor torque had a significant positive effect on delta BMD in a dose-dependent manner. The effect of this torque was the greatest among all the muscle indices. The net effect of the trunk extensor torque on delta BMD was greater than that of the VDR genotype. The trunk muscle strength was suggested to affect BMD change independently of age, body size, and the VDR genotype. Exercise programs to increase the strength of the trunk muscles would be beneficial for the prevention of osteoporosis regardless of the VDR genotypes.

Quantitative expression studies of aldolase A, B and C genes in developing embryos and adult tissues of Xenopus laevis.

We previously cloned cDNAs for all the members (A, B and C) of Xenopus aldolase gene family, and using in vitro transcribed RNAs as references, performed quantitative studies of the expression of three aldolase mRNAs in embryos and adult tissues. A Xenopus egg contains ca. 60 pg aldolase A mRNA and ca. 45 pg aldolase C mRNA, but contains only ca. 1.5 pg aldolase B mRNA. The percent composition of three aldolase mRNAs (A:B:C) changes from 56:1.5:42.5 (fertilized egg) to 54:10:36 (gastrula), to 71:14.5:14.5 (neurula) and to 73:20:7 (tadpole) during development. These results are compatible with the previous results of zymogram analysis that aldolases A and C are the major aldolases in early embryos, whose development proceeds depending on yolk as the only energy source. Aldolase B mRNA is expressed only late in development in tissues such as pronephros, liver rudiment and proctodeum which are necessary for the future dietary fructose metabolism, and the expression pattern is consistent to that in adult tissues. We also show that three aldolase genes are localized on different chromosomes as single copy genes.

Isolation of Xenopus frizzled-10A and frizzled-10B genomic clones and their expression in adult tissues and embryos.

Frizzled genes, encoding WNT receptors, play key roles in cell fate determination. Here, we isolated two Xenopus frizzled genes (Xfz10A and Xfz10B), probably reflecting pseudotetraploidy in Xenopus. Xfz10A (586 amino acids) and Xfz10B (580 amino acids) both encoded by a single exon, consisted of the N-terminal cysteine-rich domain, seven transmembrane domains, and the C-terminal Ser/Thr-X-Val motif. Xfz10A and Xfz10B were 97.0% identical at the amino acid level, and Xfz10B was 100% identical to previously reported Xfz9, yet Xfz10A was 85.3% and 62.4% identical to FZD10 and FZD9, respectively. Xfz10 mRNA appeared as 3.4 kb in adult tissues and embryos. RT-PCR analyses revealed the expression of more Xfz10A mRNA in stomach, kidney, eye, skeletal muscle, and skin, and more Xfz10B mRNA in heart and ovary, but in embryos, two mRNAs were equally expressed from the blastula stage with their peak expression at the late gastrula stage. The main site of Xfz10 mRNA expression was neural fold at the neurula stage and the dorsal region of midbrain, hindbrain, and spinal cord at the tadpole stage. These results suggest that Xfz10 has important roles in neural tissue formation.

Overexpression of S-adenosylmethionine decarboxylase (SAMDC) activates the maternal program of apoptosis shortly after MBT in Xenopus embryos.

Overexpression of S-adenosylmethionine decarboxylase (SAMDC) mRNA in 1- and 2-cell stage Xenopus embryos induces cell autonomous dissociation at the late blastula stage and developmental arrest at the early gastrula stage. The induction of cell dissociation took place "punctually" at the late blastula stage in the SAMDC-overexpressing cells, irrespective of the stage of the microinjection of SAMDC mRNA. When we examined the cells undergoing the dissociation, we found that they were TUNEL-positive and contained fragmented nuclei with condensed chromatin and fragmented DNA. Furthermore, by injecting Xenopus Bcl-2 mRNA together with SAMDC mRNA, we showed that SAMDC-overexpressing embryos are rescued completely by Bcl-2 and becometadpoles. These results indicatethat cell dissociation induced by SAMDC overexpression is due to apoptotic cell death. Since the level of S-adenosylmethionine (SAM) is greatly reduced in SAMDC-overexpressing embryos and this induces inhibition of protein synthesis accompanied by the inhibition of DNA and RNA syntheses, we conclude that deficiency in SAM induced by SAMDC overexpression activates the maternal program of apoptosis in Xenopus embryos at the late blastula stage, but not before. We propose that this mechanism serves as a surveillance mechanism to check and eliminate cells physiologically damaged during the cleavage stage.

Isolation and characterization of Xenopus laevis aldolase B cDNA and expression patterns of aldolase A, B and C genes in adult tissues, oocytes and embryos of Xenopus laevis.

Following previous cloning and expression studies of Xenopus aldolase C (brain-type) and A (muscle-type) cDNAs, we cloned here two Xenopus aldolase B (liver-type) cDNAs (XALDB1 and XALDB2, 2447 and 1490 bp, respectively) using two different liver libraries. These cDNAs had very similar ORF with only one conservative amino acid substitution, but 3'-UTR of XALDB1 contained ca. 1 kb of unrelated reiterated sequence probably ligated during library construction as shown by genomic Southern blot analysis. In adult, aldolase B mRNA (ca. 1.8 kb) was expressed strongly in kidney, liver, stomach, intestine, moderately strongly in skin, and very weakly in all the other tissues including muscles and brain, which strongly express aldolase A and C mRNAs, respectively. In oocytes and early embryos, aldolase A and C mRNAs occurred abundantly as maternal mRNAs, but aldolase B mRNA occurred only at a residual level, and its strong expression started only after the late neurula stage, mainly in liver rudiment, pronephros, epidermis and proctodeum. Thus, active expression of the gene for aldolase B, involved in dietary fructose metabolism, starts only later during development (but before the feeding stage), albeit genes for aldolases A and C, involved in glycolysis, are expressed abundantly from early stages of embryogenesis, during which embryos develop depending on yolk as the only energy source.

Maternal program of apoptosis activated shortly after midblastula transition by overexpression of S-adenosylmethionine decarboxylase in Xenopus early embryos.

When we studied polyamine metabolism in Xenopus embryos, we cloned the cDNA for Xenopus S-adenosylmethionine decarboxylase (SAMDC), which converts SAM (S-adenosylmethionine), the methyl donor, into decarboxylated SAM (dcSAM), the aminopropyl donor, and microinjected its in vitro transcribed mRNA into Xenopus fertilized eggs. We found here that the mRNA injection induces a SAM deficient state in early embryos due to over-function of the overexpressed SAMDC, which in turn induces inhibition of protein synthesis. Such embryos developed quite normally until blastula stage, but stopped development at the early gastrula stage, due to induction of massive cell dissociation and cell autolysis, irrespective of the dosage and stage of the mRNA injection. We found that the dissociated cells were TUNEL-positive, contained fragmented nuclei with ladder-forming DNA, and furthermore, rescued completely by coinjection of Bcl-2 mRNA. Thus, overexpression of SAMDC in Xenopus embryos appeared to switch on apoptotic program, probably via inhibition of protein synthesis. Here, we briefly review our results together with those reported from other laboratories. After discussing the general importance of this newly discovered apoptotic program, we propose that the maternal program of apoptosis serves as a surveillance mechanism to eliminate metabolically severely-damaged cells and functions as a 'fail-safe' mechanism for normal development in Xenopus embryos.

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.

Precision of quantitative ultrasound measurement of the heel bone and effects of ambient temperature on the parameters.

The goal of this study was to determine the magnitude of measurement error of a quantitative ultrasound (QUS) measurement system of the heel bone in a practical setting and to examine the effects of ambient temperature in the test room on QUS parameters. We assessed the intratest, intertest and interdevice coefficients of variation (CVs) for speed of sound (SOS), broadband ultrasound attenuation (BUA) and stiffness in vitro using phantoms and in vivo using volunteers. The intratest CV was the smallest and the interdevice CV was the greatest for every QUS parameter. The intertest CVs in vivo were 0.50% for SOS, 2.53% for BUA and 4.38% for stiffness. The standardized precision error (sPE) of stiffness, however, was smaller than those of the other two parameters. The intertest sPEs in vivo of the QUS parameters were 2-3 times greater than that of the spine bone mineral density (BMD) as measured by dual-energy X-ray absorptiometry (DXA). Using an average of duplicate measurements for the representative value of a subject could improve sPE of the QUS parameters to around 2 times greater than that of spine BMD. We examined five phantoms each with the QUS system under the ambient temperature conditions of 10, 20 and 30 degrees C. The lower the room temperature, the greater the values of all the QUS parameters obtained. We then assessed the effect of the season on the QUS parameters in healthy five women. SOS and stiffness were significantly greater in February (room temperature, 12.6 degrees C) than in June (22.4 degrees C) by 0.74% and 3.2% of overall means, respectively, by 10.1% and 4.3% as a standardized difference, or by 0.422 and 0.214 in Z-scores. This difference was likely to be caused by the difference in heel temperature between the seasons. The precision of the QUS system was inferior to that of conventional DXA densitometry. We recommend that institutions using several QUS system devices throughout the year at various locations monitor the precision of each device, make duplicate measurements for a single subject, use the same device for each patient being followed, and control the heel temperature of subjects by keeping the test room temperature constant throughout the year.

A novel polymorphism in the promoter region for the human osteocalcin gene: the possibility of a correlation with bone mineral density in postmenopausal Japanese women.

We present a polymorphism of the human osteocalcin gene (also known as BGP, for bone Gla protein) due to a 1 base pair (bp) substitution from cytosine to thymine at position 298 nucleotides (nt), which is at position 198 nt upstream from the BGP exon 1. This mutation was detected by single-strand conformation polymorphism analysis after polymerase chain reaction for the osteocalcin gene fragment (326 bp) and sequencing analysis. The cytosine/thymine polymorphism can be defined by restriction fragment length polymorphism analysis using a modified primer pair and the restriction endonuclease HindIII. The osteocalcin genotype was determined in 160 postmenopausal Japanese women (age 48-80 years). Osteocalcin alleles were designated according to the absence (H) or presence (h) of the HindIII restriction site. There were 12 HH, 49 Hh, and 99 hh individuals, and the allele frequencies were 22.8% for H and 77.2% for h. To determine if genetic variation influences bone mineral density (BMD) and thus can be a determinant of susceptibility to osteoporosis in older women, we examined the association of BMD with the osteocalcin genotypes found in the present study. The subjects with genotype HH had the smallest BMD and those with hh had the greatest BMD among subjects, but these differences did not reach statistical significance. The HindIII genotype showed a significant effect on the prevalence of osteopenia in the subjects, that is, women with genotype HH had a 5.74 times greater risk for osteopenia (p < 0.05) and those with genotype Hh had a 1.59 times greater risk than women with genotype hh. We identified the osteocalcin gene polymorphism, detected with the HindIII genotype, which was suggested to influence bone density and is a possible genetic marker for bone metabolism.

Age, menopause, bone turnover markers and lumbar bone loss in healthy Japanese women.

The change in lumbar vertebral bone mineral density (BMD) during a 2-year study period was examined in 167 healthy middle-aged and elderly Japanese women with reference to age, menopausal status and bone turnover markers at baseline. The perimenopausal and postmenopausal groups of the subjects showed a significant loss of BMD during the study period but the premenopausal women did not. The annual percent decrease of BMD (delta BMD) in the perimenopausal women (-2.40% in average) was significantly greater than that in either of the premenopausal (-0.01%) or over-all postmenopausal women (-0.85%). The subjects who had been postmenopausal for less than 10 years showed a significant bone loss. delta BMD in the postmenopausal women became less marked as the postmenopausal duration increased. The bone loss was accelerated for about 10 years after menopause. The pattern and magnitude of bone loss of Japanese women seemed to be similar to those of Caucasian women. The regression equation for delta BMD based on the bone turnover markers at baseline was shown to be significant in the postmenopausal women and the serum level of bone-specific alkaline phosphatase isoenzyme had a significant relation to delta BMD. However, this equation accounted for only 17.3% of the total variance of delta BMD and, hence, its validity was not sufficiently high for the prediction of bone loss in clinical settings.