Etsuko Kajita

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.

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

Abstract: 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 °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 °C) than in June (22.4 °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.

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 (DBMD) 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 DBMD 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 DBMD, 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 DBMD 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 DBMD 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.

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

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

Use of anthropometric indicators in screening for undiagnosed vertebral fractures: A cross-sectional analysis of the Fukui Osteoporosis Cohort (FOC) study

BackgroundVertebral fractures are the most common type of osteoporotic fracture. Although often asymptomatic, each vertebral fracture increases the risk of additional fractures. Development of a safe and simple screening method is necessary to identify individuals with asymptomatic vertebral fractures.MethodsLateral imaging of the spine by single energy X-ray absorptiometry and vertebral morphometry were conducted in 116 Japanese women (mean age: 69.9 ± 9.3 yr). Vertebral deformities were diagnosed by the McCloskey-Kanis criteria and were used as a proxy for vertebral fractures. We evaluated whether anthropometric parameters including arm span-height difference (AHD), wall-occiput distance (WOD), and rib-pelvis distance (RPD) were related to vertebral deformities. Positive findings were defined for AHD as ≥ 4.0 cm, for WOD as ≥ 5 mm, and for RPD as ≤ two fingerbreadths. Receiver operating characteristics curves analysis was performed, and cut-off values were determined to give maximum difference between sensitivity and false-positive rate. Expected probabilities for vertebral deformities were calculated using logistic regression analysis.ResultsThe mean AHD for those participants with and without vertebral deformities were 7.0 ± 4.1 cm and 4.2 ± 4.2 cm (p < 0.01), respectively. Sensitivity and specificity for use of AHD-positive, WOD-positive and RPD-positive values in predicting vertebral deformities were 0.85 (95% CI: 0.69, 1.01) and 0.52 (95% CI: 0.42, 0.62); 0.70 (95% CI: 0.50, 0.90) and 0.67 (95% CI: 0.57, 0.76); and 0.67 (95% CI: 0.47, 0.87) and 0.59 (95% CI: 0.50, 0.69), respectively. The sensitivity, specificity, and likelihood ratio for a positive result (LR) for use of combined AHD-positive and WOD-positive values were 0.65 (95% CI: 0.44, 0.86), 0.81 (95% CI: 0.73, 0.89), and 3.47 (95% CI: 3.01, 3.99), respectively. The expected probability of vertebral deformities (P) was obtained by the equation; P = 1-(exp [-1.327-0.040 × body weight +1.332 × WOD-positive + 1.623 × AHD-positive])-1. The sensitivity, specificity and LR for use of a 0.306 cut-off value for probability of vertebral fractures were 0.65 (95% CI: 0.44, 0.86), 0.87 (95% CI: 0.80, 0.93), and 4.82 (95% CI: 4.00, 5.77), respectively.ConclusionBoth WOD and AHD effectively predicted vertebral deformities. This screening method could be used in a strategy to prevent additional vertebral fractures, even when X-ray technology is not available.

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

Abstract: 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.

Relative contributions of age and menopause to the vertebral bone density of healthy Japanese women

The relative contributions of age and menopause to vertebral bone mineral density were evaluated based on the estimated weights for age- and menopause-related bone loss components using a mathematical model in 177 healthy female volunteers ages 35-81 years, living in a community in Fukui, Japan. Bone mineral density was determined by dual X-ray absorptiometry. The model used was that which afforded the best fit among the eight possible models to the data observed. Each model was composed of a linear function for the age-related component and a different type of function for the menopausal component, without interaction between them. The weights for these components in each model were estimated by the least-squares method. The coefficient of determination and Akaike information criterion disclosed that among the eight models tested, the model affording the best fit was composed of a logarithmic decrease in bone density with an increase in years since menopause, up to 10 years postmenopausal, with no further decline thereafter. In this model, the weights for both components were statistically significant and the type III sum of squares of the menopausal component was greater than that of the age-related component. We suggest that both age and menopause made significant contributions to the decline in vertebral bone mineral density, with the contribution of menopause being greater than that of age.

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

SummaryWe analyzed 1,217 women to examine the effect of peroxisome proliferator-activated receptors gamma (PPARγ) 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.IntroductionThe impact of PPARγ on BMD has not been conclusively established. We examined if PPARγ C161T polymorphism is associated with BMD and its change.MethodsWe 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.ResultsThe 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.ConclusionsWe conclude that the PPARγ C161T is associated with low peak bone mass.

Effect of Distributing an Evidence-Based Guideline for Prevention of Osteoporosis on Health Education Programs in Municipal Health Centers: A Randomized Controlled Trial

Background 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. Methods 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. Results 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. Conclusions 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.