Effects of the Type of Exercise Training on Bone Health Parameters in Adolescent Girls: A Systematic Review

Interventional studies offer strong evidence for exercise's osteogenic impact on bone particularly during growth. With rising osteoporosis rates in older women, enhancing bone strength early in life is crucial. Thus, investigating the osteogenic effects of different types of physical activities in young females is crucial. Despite varied findings, only two systematic reviews tried to explore this topic without examining how different types of exercise may affect bone health in adolescent girls. The first aim of this systematic review was to assess the impact of exercise training on bone health parameters in adolescent girls, and the second aim was to investigate whether the type of exercise training can modulate this effect. A systematic literature search was conducted using common electronic databases from inception - January 2023. Seven studies (355 participants) were eligible for inclusion in this systematic review. Two studies dealt with resistance training, 3 studies applied plyometric training, 1 study used team sports, and 1 study used dancing. Results indicate that plyometric training increases lumbar spine bone mass in adolescent girls. Well-designed randomized controlled trials with a proper training period (> 12 weeks) are needed to advocate a specific type of training which has the highest osteogenic effect.

[Analysis of genes related to female bone peak and osteoporosis based on bioinformatics]

OBJECTIVE

To explore and verify the genes related to female peak bone mass(PBM) and osteoporosis (OP) based on bioinformatics.

METHODS

Using GEO data, DNA microarray technology to conduct genome-wide analysis of adult female monocytes with high and low PBM. Cluster analysis, GO enrichment and KEGG analysis were used to analyze the differential genes, and the interaction network of differential genes was further analyzed. OP rat model was established and femur neck tissue staining was performed to further verify the expression of differential genes.

RESULTS

A total of 283 genes were obtained by differential gene screening. Compared with the high PBM samples, 135 genes were up-regulated and 148 genes were down-regulated in the low PBM samples. A total of 7 pathways and 12 differential genes were enriched, and there were differences in the expression of several genes involved in mineral absorption and transport, cellular immunity and other aspects. Among them, voltage-gated Ca2+ channel 1.3(CaV1.3) encoded by CACNA1D gene was significantly enhanced in the femoral neck tissue of OP rat model.

CONCLUSION

The above results suggest that the difference in the expression level of CaV1.3 gene may lead to the occurrence of OP in women with low PBM, which provides us with a potential target for the prevention and treatment of OP.

The Effects of a 1-Year Recreational Kung Fu Protocol on Bone Health Parameters in a Group of Healthy Inactive Young Men

The main aim of the current study was to explore the effects of a 1-year recreational Kung Fu protocol on bone health parameters (bone mineral content (BMC), bone mineral density (BMD), femoral neck geometry and composite indices of femoral neck strength) in a group of healthy inactive young men. 54 young inactive men voluntarily participated in this study, but only 51 of them completed it. The participants were assigned to 2 different groups: control group (n=31) and Kung Fu group (n=20). The Kung Fu group performed two sessions of recreational Kung Fu per week; the duration of each session was 45 minutes. The current study has demonstrated that whole body (WB) BMC, ultra-distal (UD) radius BMD, 1/3 radius BMD, total radius BMD, total forearm BMD, maximal strength, maximum oxygen consumption and jumping performance increased in the Kung Fu group but not in the control group. The percentages of variations in WB BMC, forearm BMD and physical performance parameters were significantly different between the two groups. In conclusion, this study suggests that recreational Kung Fu is an effective method to improve WB BMC, forearm BMD and physical performance parameters in young inactive men.

Effects of Different Levels of Weightlifting Training on Bone Mineral Density in a Group of Adolescents

The aim of the current study was to evaluate the effects of different levels of weightlifting training on bone mineral density (BMD) at different body sites (whole body (WB), lumbar spine (LS), femoral neck (FN), upper limbs (UL) and lower limbs (LL)) in a group of adolescents. Three groups of pubertal boys aged 13-15 years were recruited, including a control group (which included 13 untrained adolescents), a moderately trained group (which included 13 non-elite weightlifters, with four sessions of 2 hours per week) and a highly trained group (which included 13 elite weightlifters, with eight sessions of 2 hours per week). The three groups were paired for age and maturation index (using Tanner stages). Body composition, bone mineral content (BMC) and BMD were evaluated by dual-energy X ray absorptiometry (DXA). Physical performance variables (including weightlifting specific exercises, counter movement jump and squat jump) were measured using validated methods. Results showed that the values of BMD and physical performance variables were greater in the group of elite weightlifters compared to the group of non-elite weightlifters and the control group. In addition, the values of BMD and physical performance variables were higher in the group of the non-elite weightlifters compared to those of the control group. After adjusting for lean mass and squat jump, lumbar spine BMD, FN BMD, UL BMD and LL BMD remained significantly higher in the elite weightlifters' group compared to the two other groups. In conclusion, the current study suggests that elite adolescent weightlifters have greater bone health parameters compared to moderately-trained adolescent weightlifters and untrained adolescents.

Overview of Traditional and Environmental Factors Related to Bone Health

Bone mass in adulthood depends on growth and mineralization acquired during childhood and adolescence. It is well known that these stages of life are crucial for bone development, where genetic, nutritional, hormonal, and lifestyle factors play a significant role. Bone loss is normally a natural and slow process that begins years later after the peak bone mass is achieved and continues throughout the lifespan. Lifestyle choices in childhood and adolescence such as minimal physical activity, excessive caffeine or carbonated beverages intake, malnutrition, cigarette use, or high alcohol consumption and other factors like environmental pollutants can also negatively affect bone health and accelerate the bone loss process. The aim of this work is an overview of risk factors associated with inadequate bone health in early life.

Physical activity estimated by osteogenic potential and energy expenditure has differing associations with bone mass in young adults: the raine study

Ground impacts during physical activity may be important for peak bone mass. We found differences in how energy expenditure and impact scores estimated from a physical activity questionnaire related to bone health in young adults. Using both estimate types can improve our understanding of the skeletal benefits of physical activity.

PURPOSE

It is unclear whether mechanical loading during physical activity, estimated from physical activity questionnaires which assess metabolic equivalents of task (METs), is associated with skeletal health. This longitudinal study investigated how physical activity loading scores, assessed at ages 17 and 20 years, (a) compares with physical activity measured in METs, and (b) is associated with bone mass at age 20 years.

METHODS

A total of 826 participants from the Raine Study Gen2 were assessed for physical activity energy expenditure via the International Physical Activity Questionnaire (IPAQ) at age 17 and 20 years. Loading scores (the product of peak force and application rate) per week were subsequently estimated from the IPAQ. Whole-body and appendicular bone mineral density (BMD) at age 20 years were assessed by dual-energy X-ray absorptiometry.

RESULTS

Bland-Altman minimal detectable difference for physical activity Z- scores at age 17 and 20 years were 1.59 standard deviations (SDs) and 1.33 SDs, respectively, greater than the a priori minimal clinically important change of 0.5 SDs. Loading score, but not IPAQ score, had significant positive associations with whole-body and leg BMD after adjustment for covariates (β = 0.008 and 0.012 g/cm², respectively, for age 17 and 20 years loading scores). IPAQ score at age 20 years, but not loading score, had a significant positive association with arm BMD (β = 0.007 g/cm²).

CONCLUSION

This study revealed disagreement in associations of self-reported METs and loading score estimates with bone health in young adults. Coupling traditional energy expenditure questionnaire outcomes with bone-loading estimates may improve understanding of the location-specific skeletal benefits of physical activity in young adults.

Bone mineral density and hip structure changes over one-year in collegiate distance runners and non-athlete controls

Modification of bone is continuous throughout life and influenced by many factors, including physical activity. This study investigated changes in areal bone mineral density (aBMD) and hip structure among male and female collegiate distance runners and non-athlete controls over 12 months. Using dual-energy x-ray absorptiometry (DXA) and hip structure analysis (HSA) software, aBMD at the posterior-anterior (PA) and lateral spine, femoral neck, total hip (TH), whole body (WB), and bone geometry at the narrow neck (NN) of the femur was measured three times over 12 months. HSA included cross-sectional area (CSA), cross-sectional moment of inertia (CSMI), and Z-section modulus (Z). Male runners had significantly higher aBMD at TH and WB and greater CSA, CSMI, and Z than male controls at the end of 12 months. Female controls had higher aBMD at the PA spine than female runners at the end of 12 months. Male runners had significant increases in aBMD at the PA (p = 0.003) and lateral spine (p = 0.002), and TH (p = 0.002), female runners had significant decreases in aBMD at TH (p = 0.015) and WB (p = 0.002), male controls had significant increases in aBMD at the PA spine (p < 0.001) and WB (p < 0.001), and female controls had significant decreases in aBMD at lateral spine and TH (p = 0.008) over the year. When applying covariates of bone-free lean mass and vitamin D, male distance runners demonstrated significant improvement in CSA (3.602 ± 0.139 vs. 3.675 ± 0.122 cm², p = 0.05), CSMI (3.324 ± 0.200 to 3.467 ± 0.212 cm⁴, p < 0.05), and Z (1.81 ± 0.08 to 1.87 ± 0.08 cm³, p = 0.05) during the study. No other changes in hip structure occurred over the year. Distance running may be beneficial to aBMD and hip structure in college-age males but not females. Further research is needed on potential influences of weight-bearing activity, energy availability, and hormonal status on aBMD and hip structure in males and females.

Lifestyle and Environmental Factors Affecting Bone Mass in Japanese Female Adolescents

PURPOSE

A higher peak bone mass (PBM) in adolescence lowers the risk of osteoporosis later in life. This study examined the factors affecting bone mass in female adolescents in relation to lifestyle and environmental factors to promote bone mass development before reaching PBM.

DESIGN AND METHODS

The subjects were female students aged 15-16 years and their mothers at a public high school in Osaka, Japan. Bone mass was measured using quantitative ultrasound parameters. The body composition was measured using a multi-frequency segmental body composition analyzer. Nutrient intake, exercise habits, and maternal factors as environmental factors were examined using a questionnaire.

RESULTS

Logistic regression analyses revealed that the adolescents' lean mass was significantly related to the BUA (p < .05). The adjusted odds ratio was 1.29 (95% confidence interval [CI]: 1.07-1.54). In contrast, the adolescents' exercise habit was significantly related to the SOS (p < .05). The SOS was significantly higher in the adolescents who exercised >4 times a week than in those who exercised <2-3 times a week. The adjusted odds ratio was 2.83 (95% CI: 1.06-7.56). The adolescents' nutrient intake and maternal factors were not significant factors affecting the adolescents' bone mass.

CONCLUSIONS

The present study suggests that increasing lean mass and exercising more than four times a week were important for increasing bone mass in female adolescents.

PRACTICE IMPLICATIONS

Nurses should intervene to help female adolescents acquire healthy lifestyle skills and maintain proper body composition and exercise habits to promote bone mass development before reaching PBM.

Lentivirus-delivered ACE siRNA rescues the impaired peak bone mass accumulation caused by prenatal dexamethasone exposure in male offspring rats

Angiotensin I converting enzyme (ACE) is a major component of the renin-angiotensin system (RAS). Our previous study demonstrated that activated bone RAS was associated with low peak bone mass induced by prenatal dexamethasone exposure (PDE) in male offspring rats. However, we did not determine whether the inhibition of ACE expression could rescue PDE-induced low peak bone mass. In the present study, we treated pregnant Wistar rats with dexamethasone (0.2 mg/kg.d) on gestational days 9-20 and obtained eight weeks old male offspring rats. Some of the offspring rats from the PDE group were injected lentivirus delivered-ACE siRNA (LV-ACE siRNA) through the intra-bone marrow for 4 weeks. We found that the intra-bone marrow injection of LV-ACE siRNA rescued the impaired peak bone mass accumulation caused by PDE in male offspring rats. Moreover, LV-ACE siRNA ameliorated PDE-induced inhibition of osteogenesis and alleviated PDE-induced RAS activation in the bone tissues in vivo. Our in vitro findings further confirmed that LV-ACE siRNA reversed the suppressed osteogenic differentiation caused by dexamethasone, which can be attributed to alleviated RAS activation. In conclusion, LV-ACE siRNA rescued impaired peak bone mass accumulation caused by PDE through alleviation of local bone RAS activation in male offspring rats.

Associations between cola consumption and bone mineral density in Korean adolescents and young adults: a cross-sectional study using data from the Korea National Health and Nutrition Examination Survey, 2008-2011

The present study aimed to elucidate the relationship between cola consumption and bone mineral density (BMD) in Korean adolescents and young adults. We used data from the Korea National Health and Nutrition Examination Survey 2008–2011. A total of 2499 adolescents and young adults aged 12–25 years were included. The study participants were classified as cola drinkers and non-cola drinkers according to 24-h dietary recall data. BMD was measured using dual X-ray absorptiometry. In the male population, whole body, whole femur and femoral neck BMD in cola drinkers were lower than that of non-cola drinkers by 4% (95% CI −0⋅071, −0⋅007), 5% (−0⋅092, −0⋅012) and 5% (−0⋅090, −0⋅001), respectively. In both sex groups, cola drinkers had less frequent milk consumption than non-cola drinkers. However, there were no significant differences in cola consumption according to calcium intake in both sexes. In conclusion, cola intake and BMD were inversely associated with Korean male adolescents and young adults. Considering the importance of peak bone mass attainment at adolescents and the increasing trend in carbonated beverage consumption in South Korea, further studies are needed to elucidate the causality between cola intake and lower BMD.

Intensity of resistance training via self-reported history is critical in properly characterizing musculoskeletal health

BACKGROUND

Intensity of resistance training history might be omitted or poorly ascertained in prescreening or data questionnaires involving musculoskeletal health. Failure to identify history of high-versus low-intensity training may overlook higher effect sizes with higher intensities and therefore diminish the precision of statistical analysis with resistance training as a covariate and bias the confirmation of baseline homogeneity for experimental group designation. The purpose was to determine the degree to which a single question assessing participant history of resistance training intensity predicted differences in musculoskeletal health.

METHODS

In the first research aim, participants were separated into groups with a history (RT) and no history (NRT) of resistance training. The second research aim evaluated the history of resistance training intensity on muscular strength, lean mass, and bone mineral density (BMD), RT participants were reassigned into a low- (LIRT) or high-intensity resistance training group (HIRT). 83 males and 87 females (19.3 ± 0.6 yrs., 171.1 ± 9.9 cm, 67.1 ± 10.5 kg, 22.9 ± 2.8 BMI, 26.2 ± 7.2% body fat) completed handgrip dynamometry (HG) and dual-energy x-ray absorptiometry scans (DXA) for BMD and bone mineral-free lean mass (BFLM).

RESULTS

A 3-group method (NRT, LIRT, HIRT) reduced type-I error compared with the 2-group method (NRT, RT) in characterizing the likely effects of one's history of resistance training. For the second aim, HIRT had significantly (p < 0.05) greater HG strength (76.2 ± 2.2 kg) and arm BFLM (6.10 ± 0.16 kg) than NRT (67.5 ± 1.3 kg; 4.96 ± 0.09 kg) and LIRT (69.7 ± 2.0 kg; 5.42 ± 0.14 kg) while also showing significantly lower muscle quality (HG/BFLM) than NRT (13.9 ± 0.2 vs. 12.9 ± 0.3). HIRT had greater BMD at all sites compared to NRT (whole body = 1.068 ± 0.008 vs. 1.120 ± 0.014; AP spine = 1.013 ± 0.011 vs. 1.059 ± 0.019; lateral spine = 0.785 ± 0.009 vs. 0.846 ± 0.016; femoral neck = 0.915 ± 0.013 vs. 0.970 ± 0.022; total hip = 1.016 ± 0.012 vs. 1.068 ± 0.021 g/cm2) while LIRT revealed no significant skeletal differences to NRT.

CONCLUSIONS

Retrospective identification of high-intensity history of resistance training appears critical in characterizing musculoskeletal health and can be ascertained easily in as little as a single, standalone question. Both retrospective-questionnaire style investigations and pre-screening for potential participation in prospective research studies should include participant history of resistance training intensity.

Differences in fracture prevalence and in bone mineral density between Chinese and White Canadians: the Canadian Multicentre Osteoporosis Study (CaMos)

Fracture determinants differ between Canadians of Chinese and White descent, the former constituting the second largest visible minority group in Canada. The results of this study support the importance of characterizing bone health predictors in Canadians of different ethnicity to improve population-specific fracture prevention and treatment strategies.

PURPOSE

We aimed to compare clinical risk factors, bone mineral density, prevalence of osteoporosis, and fractures between Chinese and White Canadians to identify ethnicity-specific risks.

METHODS

We studied 236 Chinese and 8945 White Canadians aged 25+ years from the Canadian Multicentre Osteoporosis Study (CaMos). The prevalence of osteoporosis using ethnicity-specific peak bone mass (PBM), and of prior and incident low trauma fractures were assessed and compared between groups. Linear regressions, adjusting for age and anthropometric measures, were used to examine the association between baseline and 5-year changes in BMD and ethnicity.

RESULTS

Chinese participants had shorter stature, lower BMI, and lower rate of falls than White participants. Adjusted models showed no significant differences in baseline BMD between ethnic groups except in younger men where total hip BMD was 0.059 g/cm² (0.009; 0.108) lower in Chinese. Adjusted 5-year BMD change at lumbar spine was higher in older Chinese women and men compared with Whites. When using Chinese-specific PBM, the prevalence of osteoporosis in Chinese women was 2-fold lower than when using that of White women The prevalence of fractures was higher in White women compared with Chinese with differences up to 14.5% (95% CI 9.2; 19.7) and 10.5% (95% CI 4.5-16.4) in older White men. Incident fractures were rare in young Chinese compared with White participants and not different in the older groups.

CONCLUSION

Our results support the importance of characterizing bone strength predictors in Chinese Canadians and the development of ethnicity-specific fracture prediction and prevention strategies.

Low bone mineral density in children and adolescents with cancer

Maximizing accumulation of bone mass during childhood and adolescence is essential to attaining optimal peak bone mass. Childhood cancer survivors (CCS) have lower bone mineral density (BMD) than the general population. Chemotherapeutic agents including steroids and radiotherapy can affect BMD. Cancer itself, hormonal insufficiency, a poor nutritional state, and a deficit of physical activities during or after treatment also influence BMD in CCS, resulting in failure to achieve appropriate peak bone mass. Low BMD in childhood and adolescence can lead to osteoporosis in adult life and complications such as bone pain, bone deformity, and fractures. Thus, BMD in CCS should be monitored with appropriate intervention. Adequate intake of calcium and vitamin D and an increase in physical activity are recommended. Timely supplements of hormones are needed in some cases. Some publications have reported that bisphosphonate therapies using pamidronate or alendronate were well tolerated in CCS and helped increase BMD.

Oral contraceptive use, bone mineral density, and bone turnover markers over 12 months in college-aged females

INTRODUCTION

The purpose of this study was to compare bone mineral density (BMD) and bone turnover markers between combined oral contraceptive (COC) and non-COC users over 12 months.

MATERIALS AND METHODS

COC users (n = 34, age = 19.2 ± 0.5) and non-COC users (n = 28, age = 19.3 ± 0.6) provided serum at baseline, 6 months, and 12 months. C-terminal telopepetides (CTX) and pro-collagen type 1 N-terminal propeptides (P1NP) were determined using ELISA. BMD was measured at the three time points using dual-energy x-ray absorptiometry (DXA).

RESULTS

COC users had greater CTX than non-COC users at baseline (18.6 ± 8.2 vs. 13.8 ± 5.3 ng/mL, P = 0.021) and 6 months (20.4 ± 10.3 vs. 14.2 ± 8.5 ng/mL, P = 0.018). Controlling for lean mass, groups were similar in BMD. Over 12 months, non-COC users maintained BMD at the spine, while the COC users declined 2.2% in lateral spine BMD (0.773 ± 0.014 to 0.756 ± 0.014 g/cm², P = 0.03) and 0.7% in anterior-posterior spine BMD (1.005 ± 0.015 to 0.998 ± 0.015 g/cm², P = 0.069). Non-COC users increased in BMD of the whole body over 12 months (P < 0.001) while COC users had no change. Women who began COCs within 4 years after menarche had lower BMD at the hip and whole body. Women taking very low dose COCs (20 mcg ethinyl estradiol, EE) significantly declined in CTX, P1NP, and lateral spine BMD in comparison to participants using low dose COCs (30/35 mcg EE).

CONCLUSION

College-aged women who did not use COCs increased BMD of the whole body, while COC users had elevated bone turnover, declines in spinal BMD, and lack of bone acquisition of the whole body over 12 months. Young females who initiate COC use early after menarche may experience skeletal detriments.

Exercise and Peak Bone Mass

PURPOSE OF REVIEW

The main goal of this narrative review is to assess whether physical activity (PA) influences peak bone mass and fracture risk.

RECENT FINDINGS

Several randomized controlled trials (RCT) show that short-term PA intervention programs in childhood improve the accrual of bone mineral. There are now also long-term controlled PA intervention studies demonstrating that both boys and girls with daily school PA through puberty gain higher bone mineral content (BMC) and bone mineral density (BMD) and greater bone size than boys and girls with school PA 1-2 times/week. These benefits seem to be followed by a gradual reduction in expected fracture rates, so that in children with daily school PA, the incidence rate ratio (IRR) after 8 years is less than half that expected by age. Daily school PA from before to after puberty is associated with beneficial gains in bone traits and gradually lower relative fracture risk.

Age- and Strain-Related Differences in Bone Microstructure and Body Composition During Development in Inbred Male Mouse Strains

We explored age- and strain-related differences in bone microstructure and body composition in male C57BL/6J, DBA/2JRj and C3H/J mice. Bone microstructure of the femur, tibia and L4 was assessed by μCT at the age of 8, 16 and 24 weeks. The weight of several muscles and fat depots were measured at the same time points. At all timepoints, C3H/J mice had the thickest cortices followed by DBA/2JRj and C57BL/6J mice. Nevertheless, C57BL/6J mice had higher Tb.BV/TV and Tb.N, and lower Tb.Sp than DBA/2JRj and C3H/J mice at least at 24 weeks of age. Skeletal development patterns differed among strains. C57BL/6J and DBA/2JRj mice, but not C3H/J mice, experienced significant increases in the sum of the masses of 6 individual muscles by 24 weeks of age. In C57BL/6J and DBA/2JRj mice, the mass of selected fat depots reached highest values at 24 weeks, whist, in C3H/J mice, the highest values of fat depots masses were achieved at 16 weeks. Early strain differences in muscle and fat masses were largely diminished by 24 weeks of age. C3H/J and C57BL/6J mice displayed the most favorable cortical and trabecular bone parameters, respectively. Strain differences in body composition were less overt than strain specificity in bone microstructure, however, they possibly influenced aspects of skeletal development.

Distal radius bone microarchitecture: what are the differences between age 25 and old age?

This study reported that the transitional zones in older adults were enlarged at the expense of the compact-appearing cortex with a greater porosity in all cortical sub-compartments. The magnitude of differences in areal and volumetric bone mineral density (aBMD, vBMD) between older and younger groups was similar.

INTRODUCTION

Aging is strongly associated with bone loss, but little is known about magnitudes of differences in bone microarchitectures, aBMD, and vBMD from peak bone mass (PBM) to senescence. We aimed to describe differences in aBMD, vBMD, and bone microarchitecture parameters at the distal radius between older and young adults.

METHODS

We compared 201 participants, aged 62-89 years (female 47%) and 196 participants, aged 24-28 years (female 38%). Bone microarchitecture parameters at distal radius were measured using high-resolution peripheral computed tomography (HRpQCT). aBMD was measured using dual-energy X-ray absorptiometry (DXA). Unpaired t tests and chi-square tests were used to compare differences in means and proportions as appropriate.

RESULTS

Older adults had thinner compact-appearing cortices with larger (cross-sectional area: outer 30.96 mm² vs. 28.38 mm², inner 36.34 mm² vs. 32.93 mm²) and thicker (outer 0.57 mm vs. 0.54 mm, inner 0.71 mm vs. 0.65 mm) transitional zones compared with young adults (all p < 0.05). Cortical porosity was modestly higher in older adults than in young adults (54% vs. 49%, p < 0.001). The magnitude of the difference in hip aBMD between older and young adults was slightly lower than of total radial vBMD (- 0.51 SD vs. - 0.78 SD).

CONCLUSION

Compared with young adults at the time of PBM, the transitional zones in older adults were enlarged at the expense of the compact-appearing cortex with a greater porosity in all cortical sub-compartments. The similar SD differences in aBMD and vBMD between older and younger groups suggest that the differences in bone area are not leading to major artefactual change in aBMD.

Recognizing the peak bone mass (age 30) as a cutoff point to achieve the success of orthodontic implants

The aim of present study was to investigate the critical risk factor (age 30: peak bone mass) to evaluate the success of orthodontic implants. A total of 426 orthodontic implants were placed in 270 patients as orthodontic anchorages. Data were analyzed according to patient's characteristics, location of placement, implant categories, and orthodontic force. The young patients were the age ≤ 30 years and the older patients were the age > 30 years. Statistical analysis was performed and a p value < 0.05 was considered to indicate statistical significance. The Chi-square or Fisher exact test was used depending on sample sizes. The null hypothesis was no statistically significant correlation between age ≤ 30 years and age > 30 years. The overall success rate (with and without predrill) was 89.2%. The success rate of orthodontic implants was significantly larger in younger patients (89.9%) than in older patients (76.1%). Recognizing age-related factor in the success rates, older patient (> 30 years) were significant lower than young patients (≤ 30 years) in the gender (female and male), malocclusion (Class II), facial pattern (ortho and hyperdivergent), location (infrazygomatic crest), jaw (maxilla), side (right), material (titanium and stainless), length (9 mm and 10 mm), diameter (2 mm), load (< 3 weeks), and force (intrusion). Therefore, the null hypothesis was rejected. Age 30 is a cutoff point to achieve the success of orthodontic implants. The success rates of older patients (age > 30 years) were significant lower than young patients (age ≤ 30 years), especially in female.

Dietary docosahexaenoic acid contributes to increased bone mineral accretion and strength in young female Sprague-Dawley rats

Growing evidence suggests that docosahexaenoic acid (DHA: 22:6n-3) enhances bone mineral content (BMC) and bone mineral density (BMD) in adulthood and during aging, however the effects during and after sexual maturation are unclear. The aim of this study was to examine the dose-response of BMC, BMD and microarchitectural properties of bone to dietary DHA in healthy growing female rats during acquisition of peak bone mass (PBM). Female Sprague-Dawley rats (n = 12/diet) were randomized to receive a control diet (AIN-93 M, 60 g soybean oil/kg diet) or an experimental diet containing 0.1, 0.4, 0.8 and 1.2% DHA (w/w of total diet) for 10 weeks. Dietary DHA increased the whole body, lumbar spine and long bone BMC compared to the control, in addition to higher aBMD and also BMD. Additionally, an increase in cortical bone microarchitecture parameters of lumbar spine as well as peak force were observed in dietary DHA diet groups. Dietary DHA contributes to PBM when consumed during and after sexual maturation, however higher doses of DHA do not provide further benefits.

Spectrum-effect relationship between HPLC fingerprints and bioactive components of Radix Hedysari on increasing the peak bone mass of rat

The traditional Chinese medicine of Radix Hedysari plays an important role in invigorating gas for ascending, benefiting blood for promoting production of fluid, and promoting circulation for removing obstruction in collaterals, which is consistent with the principle of treatment for osteoporosis. This study is designed to investigate the bioactive components on increasing peak bone mass (PBM) by exploring the spectrum-effect relationship between chromatography fingerprints and effect. Multiple indicators are selected to evaluate the pharmacological activity. In fingerprints, 21 common peaks are obtained, five of which are identified. Furthermore, gray relational analysis (GRA) is a quantitative method of gray system theory and is used to describe the correlation degree of common peaks and pharmacological activities with relational value. 21 components are then divided into three different regions, of which ononin and calycosin play an extremely significant role in increasing PBM. In addition, factor analysis and hierarchical cluster analysis (HCA) are used to screen the optimal producing area for Radix Hedysari. This provides a comprehensive and efficient method to improve the quality evaluation of Radix Hedysari, confirming the bioactive components for PBM-enhancement and further develop its medicinal value.

Total flavonoid extract of Epimedium herb increases the peak bone mass of young rats involving enhanced activation of the AC10/cAMP/PKA/CREB pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Epimedium sagittatum brevicornum Maxim. is an important traditional Chinese herb that has long been used to promote bone fracture healing and treat osteoporosis.

AIM OF THE STUDY

Achieving peak bone mass by adolescence has now been accepted to be fundamental for preventing osteoporosis in adulthood life. This study investigated the possibility of increasing peak bone mass in young rats using the total flavonoid extract of Epimedium herb (TFE).

MATERIALS AND METHODS

TFE was intragastrically administered to one-month-old Wistar rats at a low (100 mg/kg), middle (200 mg/kg) or high dose (400 mg/kg). Whole body bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry every two weeks. When BMD of any one of TFE groups was found to be significantly higher than that of the control, all rats were sacrificed, serum samples were collected for bone turnover biochemical assays, and femurs, tibiae and vertebrae were isolated and used in BMD, mechanical, micro-structural, histomorphometric and mechanistic studies.

RESULTS

Administration of TFE at middle and high doses for two months significantly increased the whole body, femoral and vertebral BMDs, and improved the bone mechanical and micro-architectural properties. The serum turnover biochemical results and the enhanced expression levels of bone-formation regulatory genes (Runx-2, OSX, and BMP-2) demonstrated that TFE administration increased bone formation but had no effect on bone resorption. The increased phosphorylation levels in femurs of PKA and CREB and expression of AC10 (the only soluble form of adenylyl cyclase) and the increased serum cAMP level after 4 h of TFE administration indicated that TFE promoted bone formation by activating the AC10/cAMP/PKA/CREB pathway in vivo.

CONCLUSIONS

Oral administration of TFE at 200 mg/kg for two months can increase the peak bone mass of growing rats, suggesting the possibility of using total flavonoid extract of Epimedium herb to increase the peak bone mass in adolescence which is important for preventing osteoporosis in adult life.

Progressive bone impairment with age and pubertal development in neurofibromatosis type I

Bone density impairment represents an established complication in adults with neurofibromatosis type 1, while few data exist in the pediatric population. Age- and gender-adjusted bone mass decreases with age and pubertal development, identifying childhood as the best time frame to introduce prevention strategies aiming at peak bone mass achievement.

PURPOSE

The present study aims at evaluating bone mineral density (BMD) in a population of children with neurofibromatosis type I (NF-1), with particular focus on changes occurring during growth and pubertal development.

METHODS

Bone metabolic markers and bone status [by dual-energy X-ray absorptiometry scans (DXA) of the total body and lumbar spine with morphometric analysis] were assessed in 50 children (33 males; mean age ± SD, 11.6 ± 4 years). Bone mineral apparent density (BMAD), trabecular bone score (TBS), and bone strain (BS) of the lumbar spine (LS) DXA were also obtained.

RESULTS

In our cohort areal BMD (aBMD) Z-score was below the mean in 88% of the patients at LS (70% after correction for bone size) and in 86% considering total body (TB) DXA. However, aBMD Z-score was < - 2 in 12% after correction for bone size at LS and TB, respectively. Lumbar spine aBMD Z-score (r = - 0.54, P < 0.0001), LS BMAD Z-score (r = - 0.53, P < 0.0001), and TB Z-score (r = - 0.39, P = 0.005) showed a negative correlation with growth and pubertal development (P = 0.007, P = 0.02, P = 0.01, respectively), suggesting that patients failed to gain as much as expected for age.

CONCLUSION

Bone density impairment becomes more evident with growth and pubertal development in NF-1 patients, thus identifying childhood as the best time frame to introduce prevention strategies aiming at peak bone mass achievement. TBS and BS, providing bone DXA qualitative information, could be useful during longitudinal follow-up for better characterizing bone impairment in these patients.

Exposure Duration Is a Determinant of the Effect of Sinusoidal Electromagnetic Fields on Peak Bone Mass of Young Rats

We proposed a three-step strategy to obtain the optimal therapeutic parameters, which is composed of large-scale screening at cellular level, verification in animal experiments, and confirmation by a clinical trial. The objective of the current study was to test the feasibility of our strategy. Newborn rat calvarial osteoblasts were treated by 50 Hz 1.8 mT sinusoidal electromagnetic fields (SEMFs) with 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 h/days, respectively. The osteogenic differentiation and maturation of the osteoblast were assayed and compared to obtain the optimal duration. One-month-old growing rats were then treated by the same SEMFs with 0.5, 1.5, and 2.5 h/days, respectively, and the peak bone mass was analyzed after 2 months. It was found that the optimal exposure duration to promote the osteogenic differentiation and maturation of osteoblasts was 1.5 h/days, judging by the increasing degrees of ALP activity, calcified nodules formed, the gene and protein expression levels of Runx-2, BMP-2, and Col-I, as well as the expression levels of signaling proteins of the BMP-2/Smad1/5/8 pathway. The highest increase of peak bone mass after 2 months was also obtained by 1.5 h/days, judging by the results of X-ray dual-energy absorptiometry, mechanical property analysis, micro-CT scanning, and serum bone turnover marker examinations. The above results indicated that exposure duration is a determinant for the therapeutic effect of EMFs, and the optimal therapeutic effects only can be obtained by the optimal exposure duration.

Familial resemblance in trabecular and cortical volumetric bone mineral density and bone microarchitecture as measured by HRpQCT

To estimate the heritability of bone geometry, volumetric bone mineral density (vBMD) and microarchitecture of trabecular (Tb) and cortical (Ct) bone measured by high resolution peripheral quantitative computerised tomography (HRpQCT) at the distal radius and tibia and to investigate the genetic correlations of these measures. Participants were 177 mother-offspring pairs from 162 families (mothers, mean age (SD) = 52.1 (4.7) years; offspring, 25.6 (0.73) years). Trabecular and cortical bone measures were obtained by HRpQCT. Multivariable linear regression was used to analyse the association of bone measures between mother and offspring. Sequential Oligogenic Linkage Analysis Routines (SOLAR) software was utilised to conduct quantitative genetic analyses. All maternal bone measures were independently associated with the corresponding bone measures in the offspring before and after adjustment for age, sex, weight and height. Heritability estimates ranged from 24% to 67% at the radius and from 42% to 74% at the tibia. The relationship for most bone geometry measures was significantly stronger in mother-son pairs (n = 107) compared with mother-daughter pairs (n = 70) (p < 0.05). In contrast, the heritability for most vBMD and microarchitecture measures were higher in mother-daughter pairs. Bivariate analyses found moderate to strong genetic correlations across all measures between radius and tibia (R_g = 0.49 to 0.93). Genetic factors have an important role in the development of bone geometry, vBMD and microarchitecture. These factors are strongly shared for the radius and tibia but vary by sex implying a role for imprinting.

The wakefulness promoting drug Modafinil causes adenosine receptor-mediated upregulation of receptor activator of nuclear factor κB ligand in osteoblasts: Negative impact of the drug on peak bone accrual in rats

Modafinil is primarily prescribed for treatment of narcolepsy and other sleep-associated disorders. However, its off-prescription use as a cognition enhancer increased considerably, specially among youths. Given its increasing use in young adults the effect of modafinil on peak bone accrual is an important issue but has never been investigated. Modafinil treatment to young male rats caused trabecular and cortical bone loss in tibia and femur, and reduction in biomechanical strength. Co-treatment of modafinil with alendronate (a drug that suppresses bone resorption) reversed the trabecular bone loss but failed to prevent cortical loss. Modafinil increased serum type 1 pro-collagen N-terminal protein (P1NP) and collagen type 1 cross-linked C-telopeptide (CTX-1) indicating a high turnover bone loss. The drug also increased receptor activator of nuclear factor κB ligand (RANKL) to osteoprotegerin (OPG) ratio in serum which likely resulted in increased osteoclast number per bone surface. Furthermore, conditioned medium from modafinil treated osteoblasts increased the expression of osteoclastogenic genes in bone marrow-derived macrophages and the effect was blocked by RANKL neutralizing antibody. In primary osteoblasts, modafinil stimulated cAMP production and using pharmacological approach, we showed that modafinil signalled via adenosine receptors (A_2AR and A_2BR) which resulted in increased RANKL expression. ZM-241,385 (an A_2AR inhibitor) and MRS 1754 (an A_2BR inhibitor) suppressed modafinil-induced upregulation of RANKL/OPG ratio in the calvarium of new born rat pups. Our data suggests that by activating osteoblast adenosine receptors modafinil increases the production of osteoclastogenic cytokine, RANKL that in turn results in high turnover bone loss in young rats.

Causes of low peak bone mass in women

Peak bone mass is the maximum bone mass that accrues during growth and development. Consolidation of peak bone mass normally occurs during early adulthood. Low peak bone mass results from failure to achieve peak bone mass genetic potential, primarily due to bone loss caused by a variety of conditions or processes occurring at younger ages than usual. Recognized causes of low peak bone mass include genetic causes, endocrine disorders, nutritional disorders, chronic diseases of childhood or adolescence, medications, and idiopathic factors.

Stimulation of liver IGF-1 expression promotes peak bone mass achievement in growing rats: a study with pomegranate seed oil

Peak bone mass (PBM) achieved at adulthood is a strong determinant of future onset of osteoporosis, and maximizing it is one of the strategies to combat the disease. Recently, pomegranate seed oil (PSO) has been shown to have bone-sparing effect in ovariectomized mice. However, its effect on growing skeleton and its molecular mechanism remain unclear. In the present study, we evaluated the effect of PSO on PBM in growing rats and associated mechanism of action. PSO was given at various doses to 21-day-old growing rats for 90 days by oral gavage. The changes in bone parameters were assessed by micro-computed tomography and histology. Enzyme-linked immunosorbent assay was performed to analyze the levels of serum insulin-like growth factor type 1 (IGF-1). Western blotting from bone and liver tissues was done. Chromatin immunoprecipitation assay was performed to study the histone acetylation levels at IGF-1 gene. The results of the study show that PSO treatment significantly increases bone length, bone formation rate, biomechanical parameters, bone mineral density and bone microarchitecture along with enhancing muscle and brown fat mass. This effect was due to the increased serum levels of IGF-1 and stimulation of its signaling in the bones. Studies focusing on acetylation of histones in the liver, the major site of IGF-1 synthesis, showed enrichment of acetylated H3K9 and H3K14 at IGF-1 gene promoter and body. Further, the increased acetylation at H3K9 and H3K14 was associated with a reduced HDAC1 protein level. Together, our data suggest that PSO promotes the PBM achievement via increased IGF-1 expression in liver and IGF-1 signaling in bone.

Intake of omega-3 fatty acids contributes to bone mineral density at the hip in a younger Japanese female population

This study investigated the relationships between intakes of polyunsaturated fatty acids, omega-3 fatty acids, and omega-6 fatty acids and bone mineral density in Japanese women aged 19 to 25 years. Intakes of omega-3 fatty acids (n-3) were positively associated with peak bone mass at the hip.

INTRODUCTION

Lifestyle factors such as physical activity and nutrition intake are known to optimize the peak bone mass (PBM). Recently, intake of polyunsaturated fatty acids (PUFAs) has been reported to contribute to bone metabolism. In this study, the relationships of intakes of n-3 and omega-6 (n-6) fatty acids with PBM were evaluated in Japanese female subjects.

METHODS

A total of 275 healthy female subjects (19-25 years) having PBM were enrolled, and lumbar and total hip bone mineral density (BMD) and bone metabolic parameters were measured. Dietary intakes of total energy, total n-3 fatty acids, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and total n-6 fatty acids were assessed by a self-administered questionnaire. Physical activity information was also assessed.

RESULTS

The mean ± SD age was 20.6 ± 1.4 years, and BMI was 21.2 ± 2.7 kg/m². BMI and serum bone alkaline phosphatase contributed significantly to lumbar BMD on multiple regression analysis. Intake of n-3 fatty acids and physical activity were also significantly related to total hip BMD. Using EPA or DHA instead of total n-3 fatty acids in the model did not result in a significant result.

CONCLUSION

Adequate total n-3 fatty acid intake may help maximize PBM at the hip.

Effect of age and gender on serum periostin: Relationship to cortical measures, bone turnover and hormones

Periostin is an extracellular matrix protein, and in bone is expressed most highly in the periosteum. It increases bone formation through osteoblast differentiation, cell adhesion, Wnt signalling and collagen cross-linking. We hypothesised that serum periostin would be high at times of life when cortical modeling is active, in early adulthood and in older age, and that it would correlate with cortical bone measures, bone turnover and hormones that regulate cortical modeling. We conducted a cross-sectional observational study of 166 healthy men and women at three skeletal stages; the end of longitudinal growth (16-18years), peak bone mass (30-32years) and older age (over 70years). We measured serum periostin with a new ELISA optimised for human serum and plasma which recognises all known splice variants (Biomedica). We measured the distal radius and distal tibia with HR-pQCT, and measured serum PINP, CTX, sclerostin, PTH, IGF-1, estradiol and testosterone. Periostin was higher at age 16-18 than age 30-32 (1253 vs 842pmol/l, p<0.001), but not different between age 30-32 and over age 70. Periostin was inversely correlated with tibia cortical thickness and density (R -0.229, -0.233, both p=0.003). It was positively correlated with PINP (R 0.529, p<0.001), CTX (R 0.427, p<0.001) and IGF-1 (R 0.440, p<0.001). When assessed within each age group these correlations were only significant at age 16-18, except for PINP which was also significant over age 70. We conclude that periostin may have a role in IGF-1 driven cortical modeling and consolidation in young adults, but it may not be an important mediator in older adults.

Guava fruit extract and its triterpene constituents have osteoanabolic effect: Stimulation of osteoblast differentiation by activation of mitochondrial respiration via the Wnt/β-catenin signaling

The aim of this study was to evaluate the skeletal effect of guava triterpene-enriched extract (GE) in rats and identify osteogenic compounds thereof, and determine their modes of action. In growing female rats, GE at 250 mg/kg dose increased parameters of peak bone mass including femur length, bone mineral density (BMD) and biomechanical strength, suggesting that GE promoted modeling-directed bone growth. GE also stimulated bone regeneration at the site of bone injury. In adult osteopenic rats (osteopenia induced by ovariectomy, OVX) GE completely restored the lost bones at both axial and appendicular sites, suggesting a strong osteoanabolic effect. Serum metabolomics studies showed changes in several metabolites (some of which are related to bone metabolism) in OVX compared with ovary-intact control and GE treatment to OVX rats reversed those. Out of six abundantly present triterpenes in GE, ursolic acid (UA) and 2α-hydroxy ursolic acid (2α-UA) induced osteogenic differentiation in vitro as did GE by activating Wnt/β-catenin pathway assessed by phosphorylation of GSK-3β. Over-expressing of constitutively active GSK-3β (caGSK-3β) in osteoblasts abolished the differentiation-promoting effect of GE, UA and 2α-UA. All three increased both glycolysis and mitochondrial respiration but only rotenone (inhibitor of mitochondrial electron transfer) and not 2-deoxyglucose (to block glycolysis) inhibited osteoblast differentiation. In addition, caGSK-3β over-expression attenuated the enhanced mitochondrial respiration caused by GE, UA and 2α-UA. We conclude that GE has osteoanabolic effect which is contributed by UA and 2α-UA, and involve activation of canonical Wnt signaling which in turn modulates cellular energy metabolism leading to osteoblast differentiation.

Strong familial association of bone mineral density between parents and offspring: KNHANES 2008-2011

Bone mineral density (BMD) of offspring was significantly associated with their parents' BMD. Parental BMD Z-score ≤-1 was a significant predictor for BMD Z-score ≤-1 in their offspring. Peak bone mass acquisition during early adulthood is more substantially influenced by genetic factors rather than lifestyle or environmental factors.

INTRODUCTION

A person's BMD is affected by both genetic and environmental factors. Family history of osteoporosis or fragility fracture is a well-known risk factor for low bone mass or fracture. The purpose of the present study was to investigate the familial association of BMD between parents and offspring in Korean population.

METHODS

This is a cross-sectional study based on the data from the Korea National Health and Nutrition Examination Surveys (KNHANES) conducted from 2008 to 2011. A total of 5947 subjects (3135 parents and 2812 offspring) were included.

RESULTS

In age-adjusted partial correlation analyses, all BMD values acquired from the lumbar spine, femur neck, total hip, and whole body showed significant associations between parents and offspring. Among these associations, whole-body BMD showed the strongest relationship between offspring and parents. The narrow-sense heritability of BMD ranged from 0.203 to 0.542 in male offspring and from 0.396 to 0.689 in female offspring. Multiple linear regression analyses showed that offspring's BMD was independently associated with BMD of both parents after adjusting for covariates. Lifestyle or environmental factors including dietary calcium intake, serum 25-hydroxyvitamin D level, regular exercise, current smoking, and alcohol intake showed only moderate or no associations with BMD. In multiple logistic regression analyses in offspring aged 19-25 years, the son's risk of having BMD Z-score ≤-1 was associated with both parents' BMD Z-score ≤-1, while the daughter's risk was only associated with maternal BMD Z-score ≤-1.

CONCLUSIONS

Our findings confirm the strong familial association of BMD between parents and offspring in Korean population and suggest that peak bone mass acquisition during early adulthood is more substantially influenced by genetic factors rather than lifestyle or environmental factors.

Influence of Adolescents' Physical Activity on Bone Mineral Acquisition: A Systematic Review Article

BACKGROUND

This study conducted to examine and to provide a systematic literature over the influence of adolescents' physical activity (PA) in maximizing`s peak bone mass (PBM). PBM or the 'bone bank' is an important determinant in achieving healthy bone. PA is one of the bone's lifestyle contributors and high PBM is one of the major strategies for preventing osteoporosis.

METHODS

A computerized literature search using Medline (Ovid) and Scopus were conducted to identify relevant observational studies on the influence of different level of PA on bone acquisition among the healthy adolescent population. All articles included, were limited to original articles and English language.

RESULTS

Nine studies met the inclusion criteria. Reported bone outcomes were of bone mass, bone structure and bone strength. Eight studies showed positive association between adolescents' PA and high bone variables. The influence of PA may differ according to sex, skeletal sites and bone outcomes.

CONCLUSION

This study supported the importance of increase adolescents' regular PA in optimizing PBM thus preventing osteoporosis at later life.

HIV and Bone Complications: Understudied Populations and New Management Strategies

The higher risk of osteoporosis and fracture associated with HIV infection and certain antiretrovirals has been well established and the need for risk stratification among older adults increasingly recognized. This review focuses upon emerging data on bone complications with HIV/HCV coinfection, in children and adolescents, and with pre-exposure prophylaxis (PrEP), as well as new management strategies to minimize the negative effects of ART on bone.

The effects of body mass index on the hereditary influences that determine peak bone mass in mother-daughter pairs (KNHANES V)

A daughter's bone mineral density (BMD) is significantly correlated with her mother's BMD, but the daughter's body mass index (BMI) could modulate this association. Maternal inheritance dominantly affects daughters with a lower BMI, but BMI could compensate for hereditary influences in daughters with a higher BMI in terms of daughter's BMD.

INTRODUCTION

Achieving optimal peak bone mass at a young age is the best way to protect against future osteoporosis and subsequent fractures. Although environmental components influence bone mass accrual, but peak bone mass is largely programmed by inheritance. The aims of this study were to investigate the influence of maternal inheritance on the daughter's bone mass and to assess whether these influences differ according to the daughter's body mass index (BMI).

METHODS

We used data obtained from the 2010 Korean National Health and Nutrition Examination Survey V and included 187 mother-daughter pairs. Bone mineral density (BMD) was measured at the lumbar spine (LS), femur neck (FN), and total hip (TH) by using dual-energy X-ray absorptiometry (DXA). The daughter group was stratified into two groups according to the mean BMI (21.4 kg/m(2)).

RESULTS

The daughters' BMD correlated significantly with both their BMI and their mothers' Z-score for each skeletal site. In the daughters with a lower BMI (≤21.4 kg/m(2)), the BMDs at the FN and TH were affected more by the mothers' Z-score than by the daughters' BMI. Meanwhile, the influence of the daughters' BMI on their BMD was higher than that of their mothers' Z-score in daughters with a higher BMI (>21.4 kg/m(2)). Moreover, the mothers' Z-scores were a significant predictor of their daughters having Z-scores < -1.0 only in daughters with a lower BMI.

CONCLUSIONS

This study suggests that maternal inheritance is an important determinant of the daughters' bone mass, but that this hereditary factor may vary according to the daughters' BMI.

Dietary dried plum increases bone mass, suppresses proinflammatory cytokines and promotes attainment of peak bone mass in male mice

Nutrition is an important determinant of bone health and attainment of peak bone mass. Diets containing dried plum (DP) have been shown to increase bone volume and strength. These effects may be linked to the immune system and DP-specific polyphenols. To better understand these relationships, we studied DP in skeletally mature (6-month-old) and growing (1- and 2-month-old) C57Bl/6 male mice. In adult mice, DP rapidly (<2 weeks) increased bone volume (+32%) and trabecular thickness (+24%). These changes were associated with decreased osteoclast surface (Oc.S/BS) and decreased serum CTX, a marker of bone resorption. The reduction in Oc.S/BS was associated with a reduction in the osteoclast precursor pool. Osteoblast surface (Ob.S/BS) and bone formation rate were also decreased suggesting that the gain in bone in adult mice is a consequence of diminished bone resorption and formation, but resorption is reduced more than formation. The effects of DP on bone were accompanied by a decline in interleukins, TNF and MCP-1, suggesting that DP is acting in part through the immune system to suppress inflammatory activity and reduce the size of the osteoclast precursor pool. Feeding DP was accompanied by an increase in plasma phenolics, some of which have been shown to stimulate bone accrual. In growing and young adult mice DP at levels as low as 5% of diet (w/w) increased bone volume. At higher levels (DP 25%), bone volume was increased by as much as 94%. These data demonstrate that DP feeding dramatically increases peak bone mass during growth.

Associations between hypothalamic-pituitary-adrenal axis function and peak bone mass at 20years of age in a birth cohort

In older adults, high-normal circulating cortisol levels are associated with lower bone mass, but relationships between hypothalamic-pituitary-adrenal axis function and peak bone mass in young adults have not been examined. We studied 411 male and 390 female participants in the Western Australia Pregnancy Cohort (Raine) Study. At 18years of age, participants underwent a Trier Social Stress Test (TSST) with measurement of plasma and salivary cortisol at baseline and at multiple time points after stress. Cortisol responses were classified as anticipatory responder (significant fall in cortisol during the test), reactive responder (significant increase) or non-responder. At 20years, total body bone mineral content (BMC) and density (BMD) were measured by DXA. In males, after adjustment for weight, height (for BMC and bone area only), alcohol and smoking, there was a significant inverse relationship between both plasma and salivary cortisol measured at baseline in the TSST and each of BMC and BMD, such that each additional 10% of salivary cortisol was associated with reductions of 6.9g (95% CI -11.7, -2.2) in BMC, and 1.8mg/cm(2) (95% CI -3.3, -0.4) in BMD. Males classified as anticipatory responders in the TSST had 3.2% lower BMC (adjusted mean±SE: 3131±28 vs. 3233±18g, P=0.006) and 2.5% lower BMD (1108±9 vs. 1136±6mg/cm(2), P=0.022) than reactive responders. In females, there were no significant relationships between baseline cortisol or TSST responses and BMC or BMD in covariate-adjusted analyses. We conclude that in young males (but not females), higher circulating cortisol at the baseline of the stress test and an anticipatory responder pattern on the TSST are associated with lower total body bone mass.

The National Osteoporosis Foundation's position statement on peak bone mass development and lifestyle factors: a systematic review and implementation recommendations

Lifestyle choices influence 20-40 % of adult peak bone mass. Therefore, optimization of lifestyle factors known to influence peak bone mass and strength is an important strategy aimed at reducing risk of osteoporosis or low bone mass later in life. The National Osteoporosis Foundation has issued this scientific statement to provide evidence-based guidance and a national implementation strategy for the purpose of helping individuals achieve maximal peak bone mass early in life. In this scientific statement, we (1) report the results of an evidence-based review of the literature since 2000 on factors that influence achieving the full genetic potential for skeletal mass; (2) recommend lifestyle choices that promote maximal bone health throughout the lifespan; (3) outline a research agenda to address current gaps; and (4) identify implementation strategies. We conducted a systematic review of the role of individual nutrients, food patterns, special issues, contraceptives, and physical activity on bone mass and strength development in youth. An evidence grading system was applied to describe the strength of available evidence on these individual modifiable lifestyle factors that may (or may not) influence the development of peak bone mass (Table 1). A summary of the grades for each of these factors is given below. We describe the underpinning biology of these relationships as well as other factors for which a systematic review approach was not possible. Articles published since 2000, all of which followed the report by Heaney et al. [1] published in that year, were considered for this scientific statement. This current review is a systematic update of the previous review conducted by the National Osteoporosis Foundation [1]. [Table: see text] Considering the evidence-based literature review, we recommend lifestyle choices that promote maximal bone health from childhood through young to late adolescence and outline a research agenda to address current gaps in knowledge. The best evidence (grade A) is available for positive effects of calcium intake and physical activity, especially during the late childhood and peripubertal years-a critical period for bone accretion. Good evidence is also available for a role of vitamin D and dairy consumption and a detriment of DMPA injections. However, more rigorous trial data on many other lifestyle choices are needed and this need is outlined in our research agenda. Implementation strategies for lifestyle modifications to promote development of peak bone mass and strength within one's genetic potential require a multisectored (i.e., family, schools, healthcare systems) approach.

Polymorphisms of the WNT16 gene are associated with the heel ultrasound parameter in young adults

SUMMARY

Bone mineral content is influenced by genetic factors. We investigated the role of WNT16 in bone properties determined using quantitative ultrasound (QUS) on young adults. Three WNT16 genetic markers (rs2908007, rs2908004, and rs2707466) were found to have a significant association with the broadband ultrasound attenuation (BUA) measurement, suggesting that WNT16 influences bone mass in young adults.

INTRODUCTION

The aim of this study was to investigate whether genetic markers on the WNT16 gene are associated with bone mass, as assessed using QUS in a population of healthy young Spanish adults.

METHODS

A cross-sectional study was conducted on 575 individuals (mean age 20.41 ± 2.69). Bone quality was assessed using BUA measurements (dB/MHz) on the right calcaneus. Six single nucleotide polymorphisms (SNPs) (rs2908007, rs2908004, rs3801387, rs3801385, rs2707466, and rs2536184) covering the WNT16 gene were selected as genetic markers and genotyped to test their association with BUA variations.

RESULTS

The rs2908007, rs2908004, and rs2707466 SNPs were found to have a significant association with BUA (p = 0.004, p = 0.001, and p = 0.004, respectively).

CONCLUSION

We demonstrate for the first time that WNT16 genetic polymorphisms influence QUS traits in a population of young adults. This finding suggests that WNT16 might be an important genetic factor in determining peak bone mass acquisition.

A Cross-Sectional Study of the Association of VDR Gene, Calcium Intake, and Heel Ultrasound Measures in Early Adulthood

The acquisition of a high adult peak bone mass (PBM) is considered an important determinant of osteoporotic risk later in life. Genetic and environmental factors determine optimal PBM acquisition in early adulthood. The aim of this study was to test the association of vitamin D receptor (VDR) gene polymorphisms and dietary calcium intake with the bone mass of young adults. The study population comprised a total of 305 individuals (mean age 20.41; SD 2.36) whose bone mass was assessed through heel ultrasound [quantitative ultrasound measurements (QUS)] measurements (BUA, dB/MHz). The FokI G/A, rs9729 G/T, and TaqI G/A polymorphisms were selected as genetic markers of VDR. A significant difference in BUA values was observed according to gender (females 82.96; SD 15.89 vs. males 97.72; SD 16.50; p < 0.00001). The mean dietary calcium intake of the study group (827.84 mg/day; SD 347.04) was lower than the dietary reference intake for young adults (1000 mg/day) and had no association with BUA. None of the three VDR polymorphisms tested showed an association with BUA. Similarly, the analysis of VDR 3' haplotypes, estimated using rs9729 and Taq1 as tag SNPs, did not reveal any significant association with QUS traits. Our results confirm the existence of different heel QUS for women and men, as well as a tendency towards low calcium consumption by young adults, and they also suggest that the VDR gene does not play a major role in the genetic determination of QUS parameter in early adulthood.

Eating disorders, menstrual dysfunction, weight change and DMPA use predict bone density change in college-aged women

INTRODUCTION

There are limited longitudinal studies that have evaluated bone mineral density (BMD) changes in college-aged women. Our objective was to simultaneously evaluate factors influencing 4-year BMD change.

METHODS

This was a longitudinal cohort study of healthy, physically active women in the US Military Academy (n=91; average age=18.4years). Assessments over four years included: height, weight, calcium intake, physical fitness, menstrual function (annual number cycles), oral contraceptives (OCs) or depot-medroxyprogesterone acetate (DMPA) use, and eating disorder behavior (Eating Disorder Inventory; (EDI)). BMD was measured annually at the lumbar spine and total hip by dual X-ray absorptiometry and calcaneal BMD by PIXI. Slope of 4year BMD change at each skeletal site (spine total hip and calcaneus) was calculated for each woman.

RESULTS

BMD gains occurred at the spine in 50% and the hip in 36% of women. In unadjusted analyses, spine bone gain was positively related to menstrual cycle frequency (p=0.04). Spine and hip BMD loss occurred in those using DMPA (p<0.01) and those with the highest EDI quartile scores (p<0.05). BMD change was unrelated to OC use. Hip and calcaneus BMD decreased with weight loss (average 4.8+2.2lb/year) as compared to those with stable weight/weight gain (p<0.05). In multivariable analysis, spine BMD increase was significantly related to African American (AA) race, normal EDI score and normal menses. Hip BMD increase was related to AA race, weight increase and normal menses. DMPA use was associated with spine, hip, and calcaneus bone loss.

CONCLUSION

On average, BMD may modestly increase in college-aged women, in the absence of risk factors. However, risk factors including subclinical eating disorders, weight loss, menstrual dysfunction and DMPA use can have significant detrimental effects on BMD in young healthy physically active women.

Preterm Children Born Small for Gestational Age are at Risk for Low Adult Bone Mass

Cross-sectional studies suggest that premature birth and low birth weight may both be associated with low peak bone mass. We followed bone traits in preterm individuals and controls for 27 years and examined the effects of birth weight relative to gestational age [stratified as small for gestational age (SGA) or appropriate for gestational (AGA)] on adult bone mineral density (BMD). We measured distal forearm BMC (g/cm) and BMD (g/cm(2)) with single-photon absorptiometry (SPA) in 46 preterm children (31 AGA and 15 SGA) at mean age 10.1 years (range 4-16) and in 84 healthy age-matched children. The measurements were repeated 27 years later with the same SPA apparatus but then also with dual energy absorptiometry and peripheral computed tomography (pQCT). Preterm individuals were shorter (p = 0.03) in adulthood than controls. Preterm AGA individuals had similar BMC and BMD height-adjusted Z-scores in adulthood compared to controls. Preterm SGA individuals had lower distal forearm BMC and BMD height-adjusted Z-scores in adulthood than both controls and preterm AGA individuals. Preterm SGA individuals had lower gain from childhood to adulthood in distal forearm BMC height-adjusted Z-scores than controls (p = 0.03). The deficits in preterm SGA individuals in adulthood were also captured by DEXA in height-adjusted femoral neck (FN) BMC Z-score and height-adjusted FN BMD Z-score and by pQCT in tibial cross-sectional area (CSA) Z-score and stress strain index (SSI) Z-score, where all measurements were lower than controls (all p values <0.05). Preterm SGA individuals are at increased risk of reaching low adult bone mass, at least partly due to a deficit in the accrual of bone mineral during growth. In our cohort, we were unable to find a similar risk in preterm AGA individuals.

Predictors of trabecular bone score in school children

Trabecular bone score (TBS) is a DXA-based tool that assesses bone texture and reflects microarchitecture. It has been shown to independently predict the risk of osteoporotic fracture in the elderly. In this study, we investigated the determinants of TBS in adolescents.

INTRODUCTION

TBS is a gray-level textural measurement derived from lumbar spine DXA images. It appears to be an index of bone microarchitecture that provides skeletal information additional to the standard BMD measurement and clinical risk factors. Our objectives were to characterize the relationship between TBS and both age and pubertal stages and identify other predictors in adolescents.

METHODS

We assessed TBS by reanalyzing spine DXA scan images obtained from 170 boys and 168 girls, age range 10-17 years, gathered at study entry and at 1 year, using TBS software. The results are from post hoc analyses obtained using data gathered from a prospective randomized vitamin D trial. Predictors of TBS were assessed using t test or Pearson's correlation and adjusted using regression analyses, as applicable.

RESULTS

The mean age of the study population was 13.2 ± 2.1 years, similar between boys and girls. Age, height, weight, sun exposure, spine BMC and BMD, body BMC and BMD, and lean and fat mass are all significantly correlated with TBS at baseline (r = 0.20-0.75, p < 0.035). Correlations mostly noted in late-pubertal stages. However, after adjustment for BMC, age remained an independent predictor only in girls.

CONCLUSIONS

In univariate exploratory analyses, age and pubertal stages were determinants of TBS in adolescents. Studies to investigate predictors of TBS and to investigate its value as a prognostic tool of bone fragility in the pediatric population are needed.

Conflicting reports on vitamin D supplementation: Evidence from randomized controlled trials

A significant number of children and adolescents worldwide have low serum 25(OH)D values relative to the 2010 Institute of Medicine criteria. Since approximately 90% of adult bone mineral content (BMC) is accrued by the end of adolescence, and approximately 40% of adult BMC accumulated during the 4 years surrounding peak BMC velocity, low circulating 25(OH)D during this time may attenuate gains in adolescent bone strength. Reduced bone mineralization and strength during pubertal growth tracks into adulthood and could lead to an increased risk of skeletal fractures. Observational studies examining the relationships between vitamin D and bone are conflicting and few randomized controlled trials (RCTs) have been conducted in children and adolescents. Four of these RCTs, however, provide moderate support for the role of vitamin D supplementation on BMC accrual in adolescent females with baseline serum concentrations <50 nmol/L. Though the daily vitamin D doses employed in these trials ranged from 200 to 3000 IU per day, it is not clear if a dose-response effect exists. Specific maturational stages were associated with optimal bone responses in each of these trials, but they were not consistent across studies. Furthermore, data on male children and among ethnicities other than white and Asian youth were limited in these studies and therefore reduce the generalizability of the findings. Finally, the evidence linking vitamin D supplementation to improved muscle gains and function, important variables to consider in bone health investigations during growth, might imply indirect effects of supplementation on bone. In conclusion, future RCTs are warranted that address the mechanisms by which vitamin D improves bone mineralization in adolescents, including trials that address the impact of vitamin D on muscle function.