Correlation of obesity and osteoporosis: effect of fat mass on the determination of osteoporosis

Abdominal obesity and hip fracture: results from the Nurses' Health Study and the Health Professionals Follow-up Study

Abdominal obesity might increase fracture risk. We studied the prospective associations between waist circumference, waist-to-hip ratio, and hip fracture. The indicators of abdominal obesity were associated with increased hip fracture risk in women, but not in men. The increased risk was restricted to women with low physical activity.

INTRODUCTION

Low weight is an established risk factor for osteoporosis and hip fracture. However, the association between fat tissue, muscle, and bone is complex, and abdominal obesity might increase fracture risk. We studied the prospective associations between indicators of abdominal obesity and hip fracture in two large US cohorts.

METHODS

At baseline in 1986 and through biennial follow-up, information on hip fracture and potential risk factors was collected in 61,677 postmenopausal women and 35,488 men above age 50. Waist and hip circumferences were reported at baseline and updated twice.

RESULTS

During follow-up, 1168 women and 483 men sustained a hip fracture. After controlling for known risk factors, there was a significant association in women between increasing waist circumference and hip fracture (RR per 10-cm increase 1.13 (95 % CI 1.04-1.23) and between increasing waist-to-hip ratio and hip fracture (RR per 0.1 unit increase 1.14 (95 % CI 1.04-1.23), but these associations were not seen in men. In women, both measures interacted with physical activity. Those in the highest (≥0.90) versus lowest (<0.75) category of waist-to-hip ratio had increased risk of hip fracture if their activity was less than the population median (RR = 1.61, 95 % CI 1.18-2.19) but not if their activity was higher (RR = 1.00, 95 % CI 0.72-1.40). A similar pattern was found for waist circumference.

CONCLUSION

Indicators of abdominal obesity were associated with increased hip fracture risk after controlling for BMI in women. The increased risk was restricted to women with low physical activity. In men, no significant associations were found.

BMI and BMD: The Potential Interplay between Obesity and Bone Fragility

Recent evidence demonstrating an increased fracture risk among obese individuals suggests that adipose tissue may negatively impact bone health, challenging the traditional paradigm of fat mass playing a protective role towards bone health. White adipose tissue, far from being a mere energy depot, is a dynamic tissue actively implicated in metabolic reactions, and in fact secretes several hormones called adipokines and inflammatory factors that may in turn promote bone resorption. More specifically, Visceral Adipose Tissue (VAT) may potentially prove detrimental. It is widely acknowledged that obesity is positively associated to many chronic disorders such as metabolic syndrome, dyslipidemia and type 2 diabetes, conditions that could themselves affect bone health. Although aging is largely known to decrease bone strength, little is yet known on the mechanisms via which obesity and its comorbidities may contribute to such damage. Given the exponentially growing obesity rate in recent years and the increased life expectancy of western countries it appears of utmost importance to timely focus on this topic.

Bone Mineral Density in the Noninstitutionalized Elderly: Influence of Sociodemographic and Anthropometric Factors

Objective. Analysis of bone mineral density (BMD) in the elderly and its associated factors according to sex. Methods. A cross-sectional study is presented herein, with a random sample of 132 noninstitutionalized elderly people. Individuals who did not use diuretics were excluded. BMD was obtained from examination of total body densitometry and its association with sociodemographic variables, lifestyle, anthropometric, and body composition was verified. Results. Mean BMD for men was 1.17 ± 0.12 g/cm(2) and for women was 1.04 ± 0.11 g/cm(2). Higher education was associated with higher BMD values in men (p < 0.05). There was a reduction in BMD in the age group 75-79 years of age in women and over 80 years of age in men (p < 0.05). Underweight was associated with significantly low BMD for both sexes (p < 0.01), while normal weight was associated with low BMD in women (p < 0.001). Discussion. The elderly with low schooling and in older age groups are more probable to also present low BMD. Lower levels of body mass index also indicated towards low BMD.

Traumatic injuries among adult obese patients in southern Taiwan: a cross-sectional study based on a trauma registry system

BACKGROUND

The adverse impact of obesity has been extensively studied in the general population; however, the added risk of obesity on trauma-related mortality remains controversial. This study investigated and compared mortality as well injury patterns and length of stay (LOS) in obese and normal-weight patients hospitalized for trauma in the hospital and intensive care unit (ICU) of a Level I trauma center in southern Taiwan.

METHODS

Detailed data of 880 obese adult patients with body mass index (BMI) ≥ 30 kg/m(2) and 5391 normal-weight adult patients (25 > BMI ≥ 18.5 kg/m(2)) who had sustained a trauma injury between January 1, 2009 and December 31, 2013 were retrieved from the Trauma Registry System. Pearson's chi-squared, Fisher's exact, and independent Student's t-tests were used to compare differences between groups. Propensity score matching with logistic regression was used to evaluate the effect of obesity on mortality.

RESULTS

In this study, obese patients were more often men, motorcycle riders and pedestrians, and had a lower proportion of alcohol intoxication compared to normal-weight patients. Analysis of Abbreviated Injury Scale scores revealed that obese trauma patients presented with a higher rate of injury to the thorax, but a lower rate of facial injuries than normal-weight patients. No significant differences were found between obese and normal-weight patients regarding Injury Severity Score (ISS), Trauma-Injury Severity Score (TRISS), mortality, the proportion of patients admitted to the ICU, or LOS in ICU. After propensity score matching, logistic regression of 66 well-matched pairs did not show a significant influence of obesity on mortality (odds ratio: 1.51, 95% confidence interval: 0.54-4.23 p = 0.438). However, significantly longer hospital LOS (10.6 vs. 9.5 days, respectively, p = 0.044) was observed in obese patients than in normal-weight patients, particularly obese patients with pelvic, tibial, or fibular fractures.

CONCLUSION

Compared to normal-weight patients, obese patients presented with different injury characteristics and bodily injury patterns but no difference in mortality.

Obesity does not aggravate osteoporosis or osteoblastic insulin resistance in orchiectomized rats

The present study aimed to test the hypothesis that testosterone deprivation impairs osteoblastic insulin signaling, decreases osteoblast survival, reduces bone density, and that obesity aggravates those deleterious effects in testosterone-deprived rats. Twenty four male Wistar rats underwent either a bilateral orchiectomy (O, n=12) or a sham operation (S, n=12). Then the rats in each group were further divided into two subgroups fed with either a normal diet (ND) or a high-fat diet (HF) for 12 weeks. At the end of the protocol, blood samples were collected to determine metabolic parameters and osteocalcin ratios. The tibiae were collected to determine bone mass using microcomputed tomography and for osteoblast isolation. The results showed that rats fed with HF (sham-operated HF-fed rats (HFS) and ORX HF-fed rats (HFO)) developed peripheral insulin resistance and had decreased trabecular bone density. In ND-fed rats, only the ORX ND-fed rats (NDO) group had decreased trabecular bone density. In addition, osteoblastic insulin resistance, as indicated by a decrease in tyrosine phosphorylation of the insulin receptor and Akt, were observed in all groups except the sham-operated ND-fed rats (NDS) rats. Those groups, again with the exception of the NDS rats, also had decreased osteoblastic survival. No differences in the levels of osteoblastic insulin resistance and osteoblastic survival were found among the NDO, HFS, and HFO groups. These findings suggest that either testosterone deprivation or obesity alone can impair osteoblastic insulin signaling and decrease osteoblastic survival leading to the development of osteoporosis. However, obesity does not aggravate those deleterious effects in the bone of testosterone-deprived rats.

Relationship of sarcopenia and body composition with osteoporosis

The purpose of the study is to investigate the relationship between sarcopenia and body composition and osteoporosis in cohorts of three different races with a total of 17,891 subjects. Lean mass and grip strength were positively associated with bone mineral densities (BMDs). Subjects with sarcopenia were two times more likely to have osteoporosis compared with normal subjects.

INTRODUCTION

The relationship between sarcopenia and osteoporosis is not totally clear. First, the present study assessed this relationship by using two different definitions for sarcopenia. Second, we examined the associations of body composition (including muscle mass as a major and important component) and muscle strength on regional and whole-body BMDs.

METHODS

In total, 17,891 subjects of African American, Caucasian, and Chinese ethnicities were analyzed. Sarcopenia was defined by relative appendicular skeletal muscle mass (RASM) cut points and also by the definition of the European Working Group on Sarcopenia in Older People (low RASM plus low muscle function). Multiple regression analyses were conducted to examine the association of fat mass, lean mass (including muscle mass), and grip strength with regional and whole-body BMDs. Multivariate logistic regression analysis was performed to explore the association between sarcopenia and osteopenia/osteoporosis.

RESULTS

BMDs were positively associated with lean mass and negatively associated with fat mass, after controlling for potential confounders. Grip strength was significantly associated with higher BMDs. Each standard deviation (SD) increase in RASM resulted in a ~37 % reduction in risk of osteopenia/osteoporosis (odds ratio (OR) = 0.63; 95 % confidence interval (CI) = 0.59, 0.66). Subjects with sarcopenia defined by RASM were two times more likely to have osteopenia/osteoporosis compared with the normal subjects (OR = 2.04; 95 % CI = 1.61, 2.60). Similarly, subjects with sarcopenia (low muscle mass and low grip strength) were ~1.8 times more likely to have osteopenia/osteoporosis than normal subjects (OR = 1.87; 95 % CI = 1.09, 3.20).

CONCLUSIONS

High lean mass and muscle strength were positively associated with BMDs. Sarcopenia is associated with low BMD and osteoporosis.

Long-Term Supplementation of Green Tea Extract Does Not Modify Adiposity or Bone Mineral Density in a Randomized Trial of Overweight and Obese Postmenopausal Women

BACKGROUND

Green tea extract (GTE) consumption has been linked to favorable changes in adiposity and bone mineral density (BMD), although it is unknown if these effects are due to green tea catechins or caffeine. The catechol-O-methyltransferase (COMT) genotype may also modify these associations.

OBJECTIVE

We examined the impact of decaffeinated GTE on body composition (using dual-energy X-ray absorptiometry) and obesity-associated hormones.

METHODS

The Minnesota Green Tea Trial was a 12-mo randomized, double-blind, placebo-controlled clinical trial in 937 postmenopausal women (aged 50-70 y) assigned to receive either GTE containing 843 mg (-)-epigallocatechin-3-gallate or placebo. This substudy was conducted in 121 overweight/obese participants [body mass index (BMI) (kg/m(2)) ≥25.0].

RESULTS

There were no differences in changes in BMI (-0.13 ± 0.11 compared with -0.05 ± 0.11; P = 0.61), total fat mass (-0.30 ± 0.16 compared with -0.12 ± 0.15 kg; P = 0.40), percentage of body fat (-0.15% ± 0.17% compared with -0.15% ± 0.16%; P = 0.99), or BMD (-0.006 ± 0.002 compared with -0.003 ± 0.002 g/cm(2); P = 0.49) over 12 mo between women taking GTE (n = 61) and those taking a placebo (n = 60). Interactions were observed between treatment and time for gynoid percentage of fat (%fat) and tissue %fat. Gynoid %fat increased from baseline to month 12 in the placebo group as baseline BMI increased and decreased over time as baseline BMI increased in the GTE group (P-interaction = 0.02). Tissue %fat increased from baseline to month 12 in the placebo group as baseline BMI increased. In the GTE group, tissue %fat decreased during the intervention as baseline BMI increased (P-interaction = 0.04). No changes were seen in circulating leptin, ghrelin, adiponectin, or insulin concentrations. COMT genotype did not modify the effect of GTE on any variable.

CONCLUSIONS

Decaffeinated GTE was not associated with overall reductions in adiposity or improvements in BMD in overweight/obese postmenopausal women. However, GTE may be beneficial for reduction in tissue and gynoid %fat in individuals with higher BMI. This clinical trial was registered at www.clinicaltrials.gov as NCT00917735.

Assessment of diet and recognition of nutritional deficiencies in paleopathological studies: A review

An essential part of paleopathology is the study of diet and nutrition as well as inferring aspects of diet and nutrition from the skeletal pathology. Interpretation of nutritional and metabolic disease-related pathologies often provides additional insight into the daily social and cultural practices of people. However, precise diagnoses of specific vitamin-related deficiencies in archaeological skeletal remains are still quite problematic and specific diagnoses are rarely possible. This partly stems from the fact that many nutritional or metabolic diseases do not necessarily result in an osteological response and when they do, the comorbidity and analogous osteological responses to vitamin deficiencies may hamper the definite diagnosis of nutrition-related disease. Clin. Anat. 29:862-869, 2016. © 2016 Wiley Periodicals, Inc.

Body Mass Index May Positively Correlate with Bone Mineral Density of Lumbar Vertebra and Femoral Neck in Postmenopausal Females

Background

Our study aimed to explore the relationship between body mass index (BMI) and bone mineral density (BMD) of lumbar vertebra and femoral neck in postmenopausal females.

Material/Methods

From September 2012 to September 2014, 236 healthy postmenopausal females who underwent physical examinations at the Women & Children’s Health Care Hospital of Linyi were enrolled into our study. These subjects were divided into 3 groups: underweight group, normal weight group, and overweight group. In addition, there were 2 age stratifications: <60 years old and ≥60 years old. DPX-L type dual-energy X-ray bone densitometry (American Lunar Company) was used to measure the BMD of lumbar vertebra and femoral neck in the recruited subjects. Pearson test was used for correlation analysis.

Results

BMDs and T-scores of lumbar vertebra (L₁–L₄), femoral neck, proximal femur, and Ward’s triangle region among the groups were ranked as follows: underweight group < normal weight group < overweight group. There were significant differences in body weight and BMI among the underweight, normal weight, and overweight groups (P<0.05). The T-scores of all examined anatomic locations showed significant differences between the underweight group and normal weight group, as well as between the underweight group and overweight group (both P<0.05). Only the T-scores of lumbar vertebra L₂–L₄ had significant differences between the normal weight group and overweight group (P<0.05). The BMDs of all anatomic components under study showed statistical differences in both age stratifications between the overweight group and underweight group, as well as between the overweight group and normal weight group (both P<0.05). When stratified above 60 years old, the BMDs of lumbar vertebra (L₁, L₂ and L₄) showed statistical differences between the normal weight group and underweight group (P<0.05). Various factors could be ranked according to the absolute values of correlation coefficients as below: body weight, BMI, height, and age. Body weight, BMI, and height were positively correlated with the BMDs of all examined anatomic locations (P<0.05). However, age was negatively correlated with the various components of the body (lumbar vertebra L₁, L₂ and L₄, femoral neck, proximal femur, Ward’s triangle region: P<0.05; lumbar vertebra L₃: P>0.05).

Conclusions

Our study provides evidence that body weight and BMI are important factors affecting BMD. Postmenopausal females with low BMI are more likely to have osteopenia, and are likely to develop osteoporosis. BMI can be used as an important index to prevent osteoporosis.

Advances in high-density lipoprotein physiology: surprises, overturns, and promises

Emerging evidence strongly supports that changes in the HDL metabolic pathway, which result in changes in HDL proteome and function, appear to have a causative impact on a number of metabolic disorders. Here, we provide a critical review of the most recent and novel findings correlating HDL properties and functionality with various pathophysiological processes and disease states, such as obesity, type 2 diabetes mellitus, nonalcoholic fatty liver disease, inflammation and sepsis, bone and obstructive pulmonary diseases, and brain disorders.

Ladder-Climbing Training Prevents Bone Loss and Microarchitecture Deterioration in Diet-Induced Obese Rats

Resistance exercise has been proved to be effective in improving bone quality in both animal and human studies. However, the issue about whether resistance exercise can inhibit obesity-induced bone loss has not been previously investigated. In the present study, we have evaluated the effects of ladder-climbing training, one of the resistance exercises, on bone mechanical properties and microarchitecture in high-fat (HF) diet-induced obese rats. Twenty-four rats were randomly assigned to the Control, HF + sedentary (HF-S) and HF + ladder-climbing training (HF-LCT) groups. Rats in the HF-LCT group performed ladder-climbing training for 8 weeks. The results showed that ladder-climbing training significantly reduced body and fat weight, and increased muscle mass along with a trend toward enhanced muscle strength in diet-induced obese rats. MicroCT analysis demonstrated that obesity-induced bone loss and architecture deterioration were significantly mitigated by ladder-climbing training, as evidenced by increased trabecular bone mineral density, bone volume over total volume, trabecular number and thickness, and decreased trabecular separation and structure model index. However, neither HF diet nor ladder-climbing training had an impact on femoral biomechanical properties. Moreover, ladder-climbing training significantly increased serum adiponectin, decreased serum leptin, TNF-α, IL-6 levels, and downregulated myostatin (MSTN) expression in diet-induced obese rats. Taken together, ladder-climbing training prevents bone loss and microarchitecture deterioration in diet-induced obese rats through multiple mechanisms including increasing mechanical loading on bone due to improved skeletal muscle mass and strength, regulating the levels of myokines and adipokines, and suppressing the release of pro-inflammatory cytokines. It indicates that resistance exercise may be a promising therapy for treating obesity-induced bone loss.

MR-Based Assessment of Bone Marrow Fat in Osteoporosis, Diabetes, and Obesity

Bone consists of the mineralized component (i.e., cortex and trabeculae) and the non-mineralized component (i.e., bone marrow). Most of the routine clinical bone imaging uses X-ray-based techniques and focuses on the mineralized component. However, bone marrow adiposity has been also shown to have a strong linkage with bone health. Specifically, multiple previous studies have demonstrated a negative association between bone marrow fat fraction (BMFF) and bone mineral density. Magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) are ideal imaging techniques for non-invasively investigating the properties of bone marrow fat. In the present work, we first review the most important MRI and MRS methods for assessing properties of bone marrow fat, including methodologies for measuring BMFF and bone marrow fatty acid composition parameters. Previous MRI and MRS studies measuring BMFF and fat unsaturation in the context of osteoporosis are then reviewed. Finally, previous studies investigating the relationship between bone marrow fat, other fat depots, and bone health in patients with obesity and type 2 diabetes are presented. In summary, MRI and MRS are powerful non-invasive techniques for measuring properties of bone marrow fat in osteoporosis, obesity, and type 2 diabetes and can assist in future studies investigating the pathophysiology of bone changes in the above clinical scenarios.

The Trochanteric Localization is a Mediator of Slower Short-Term Functional Recovery in Overweight and Obese Elderly Women with Recent Hip Fracture: The BREAK Study

The hypothesis tested in this study, carried out on elderly Italian women with recent hip fracture, was to assess the extent to which the effect of a condition of being overweight/obese on short-term functional recovery as evaluated by the "time to permitted load" could be explained by a mediator variable (type of hip fracture). We studied 727 women aged 60 years or over with a recent low trauma surgically treated hip fracture and for whom an information on post-surgery complications and on the time to permitted load was available. To assess for mediation, the statistical analyses were carried out following the procedure described by Baron and Kenny. In this study, 46 % of women with hip fracture presented a time to permitted load of ≥ 10 days. The women with a post-surgery time to permitted load of ≥ 10 days showed a significantly higher proportion of trochanteric fracture localization (72.1 vs 42 %), of total overweight/obesity (46.5 vs 36.8 %) and of post-surgery complications (38.8 vs 18.8 %). The mediating effect of hip fracture localization on the association between overweight/obesity and the time of permitted load was demonstrated and confirmed in a multivariate logistic regression model. This study, carried out using a "mediator" statistical analysis, suggests that in elderly women with hip fracture being overweight/obese is associated with a slower short-term functional recovery as evaluated by the time to permitted load and that this association is mediated by the trochanteric localization of hip fracture.

A Root-Based Combination Supplement Containing Pueraria lobata and Rehmannia glutinosa and Exercise Preserve Bone Mass in Ovariectomized Rats Fed a High-Fat Diet

The aim of this study was to evaluate the effects of a supplement containing Pueraria lobata/Rehmannia glutinosa (PR) root extracts on bone turnover in ovariectomized (OVX) rats (a model for postmenopausal osteoporosis). Female Sprague-Dawley rats (8 weeks old) were randomized into eight groups: sham-operated rats with low-fat control diet + vehicle, OVX rats with low-fat control diet + vehicle, OVX rats with high-fat diet (HFD) + vehicle, OVX rats with HFD + vehicle + exercise, OVX rats with HFD + PR (400 mg/kg body weight/day p.o.), OVX rats with HFD + PR + exercise, OVX rats with HFD + 17β-estradiol (0.5 mg/kg body weight/day p.o.), OVX rats with HFD + 17β-estradiol + exercise. Bone microarchitecture, bone turnover markers (e.g., plasma alkaline phosphatase and osteocalcin), expressions of osteogenic and resorptive gene markers in the bone were measured. Eight weeks of PR and/or aerobic exercise improved cortical microarchitecture of the femur and decreased markers of bone turnover and expression of skeletal osteoclastogenic genes in the femur. PR supplementation combined with exercise preserved bone loss induced by estrogen deficiency and should be investigated further as an alternative to hormone replacement therapy for preventing osteoporosis in postmenopausal women.

Skeletal deterioration following ovarian failure: can some features be a direct consequence of estrogen loss while others are more related to physical inactivity?

Findings on experimental animals show that ovarian failure is accompanied by a decrease in motor activity. As mechanical loading has a vital role in the maintenance of skeletal health, our aim was to determine to what extent this decrease in motor activity contributes to ovariectomy-induced bone loss. Thirty-two female Wistar rats were ovariectomized or sham-operated and housed in standard cages or with access to running wheels for 36 weeks with their running distance monitored. Markers of bone turnover were assayed in the serum, and bone geometry, trabecular and cortical bone microarchitecture, mineralization degree, and biomechanical properties were assessed in the femur. Differences between groups were determined by one-way ANOVA. Although reduced motor activity and sex steroid deficiency both resulted in decreases in trabecular bone volume, trabecular number decreases were mostly associated with sex steroid deficiency, whereas trabecular thickness decreases were mostly associated with sedentary behavior. Cortical bone appeared to be more sensitive to variations in motor activity, whereas bone turnover rate and bone tissue mineralization degree seemed to be primarily affected by sex steroid deficiency, even though they were further aggravated by sedentary behavior. Increases in femur length were mostly a consequence of sex steroid deficiency, whereas femoral neck length was also influenced by sedentary behavior. Differences in mechanical properties resulted mostly from differences in physical activity. Both the direct effect of sex steroid deficiency and the indirect effect of motor activity changes are implicated in bone loss following ovariectomy.

Inhibiting myostatin signaling prevents femoral trabecular bone loss and microarchitecture deterioration in diet-induced obese rats

Besides resulting in a dramatic increase in skeletal muscle mass, myostatin (MSTN) deficiency has a positive effect on bone formation. However, the issue about whether blocking MSTN can inhibit obesity-induced bone loss has not been previously investigated. In the present study, we have evaluated the effects of MSTN blocking on bone quality in high-fat (HF), diet-induced obese rats using a prepared polyclonal antibody for MSTN (MsAb). Twenty-four rats were randomly assigned to the Control, HF and HF + MsAb groups. Rats in the HF + MsAb group were injected once a week with purified MsAb for eight weeks. The results showed that MsAb significantly reduced body and fat weight, and increased muscle mass and strength in the HF group. MicroCT analysis demonstrated that obesity-induced bone loss and architecture deterioration were significantly mitigated by MsAb treatment, as evidenced by increased bone mineral density, bone volume over total volume, trabecular number and thickness, and decreased trabecular separation and structure model index. However, neither HF diet nor MsAb treatment had an impact on femoral biomechanical properties including maximum load, stiffness, energy absorption and elastic modulus. Moreover, MsAb significantly increased adiponectin concentrations, and decreased TNF-α and IL-6 levels in diet-induced obese rats. Taken together, blocking MSTN by MsAb improves bone quality in diet-induced obese rats through a mechanotransduction pathway from skeletal muscle, and the accompanying changes occurring in the levels of circulating adipokines and pro-inflammatory cytokines may also be involved in this process. It indicates that the administration of MSTN antagonists may be a promising therapy for treating obesity and obesity-induced bone loss.

Contributions of fat mass and fat distribution to hip bone strength in healthy postmenopausal Chinese women

The fat and bone connection is complicated, and the effect of adipose tissue on hip bone strength remains unclear. The aim of this study was to clarify the relative contribution of body fat accumulation and fat distribution to the determination of proximal femur strength in healthy postmenopausal Chinese women. This cross-sectional study enrolled 528 healthy postmenopausal women without medication history or known diseases. Total lean mass (LM), appendicular LM (ALM), percentage of lean mass (PLM), total fat mass (FM), appendicular FM (AFM), percentage of body fat (PBF), android and gynoid fat amount, android-to-gynoid fat ratio (AOI), bone mineral density (BMD), and proximal femur geometry were measured by dual energy X-ray absorptiometry. Hip structure analysis was used to compute some variables as geometric strength-related parameters by analyzing the images of the hip generated from DXA scans. Correlation analyses among anthropometrics, variables of body composition and bone mass, and geometric indices of hip bone strength were performed with stepwise linear regression analyses as well as Pearson's correlation analysis. In univariate analysis, there were significantly inverse correlations between age, years since menopause (YSM), hip BMD, and hip geometric parameters. Bone data were positively related to height, body weight, LM, ALM, FM, AFM, and PBF but negatively related to AOI and amount of android fat (all P < 0.05). AFM and AOI were significantly related to most anthropometric parameters. AFM was positively associated with height, body weight, and BMI. AFM was negatively associated with age and YSM. AOI was negatively associated with height, body weight, and BMI. AOI positively associated with age and YSM. LM, ALM, and FM had a positive relationship with anthropometric parameters (P < 0.05 for all). PLM had a negative relationship with those parameters. The correlation between LM, ALM, FM, PLM, ALM, age, and YSM was not significant. In multivariate linear regression analysis, the hip bone strength was observed to have a consistent and unchanged positive association with AFM and a negative association with AOI, whereas its association with other variables of body composition was not significant after adjusting for age, years since menopause, height, body weight, and BMI. AFM may be a positively protective effect for hip bone strength while AOI, rather than android fat, shows a strong negative association with hip bone strength after making an adjustment for confounders (age, YSM, height, body weight, and BMI) in healthy postmenopausal Chinese women. Rational weight control and AOI reduction during menopause may have vital clinical significance in decreasing postmenopausal osteoporosis.

Integrative systems analysis of diet-induced obesity identified a critical transition in the transcriptomes of the murine liver and epididymal white adipose tissue

BACKGROUND

It is well known that high-fat diet (HFD) can cause immune system-related pathological alterations after a significant body weight gain. The mechanisms of the delayed pathological alterations during the development of diet-induced obesity (DIO) are not fully understood.

METHODS

To elucidate the mechanisms underlying DIO development, we analyzed time-course microarray data obtained from a previous study. First, differentially expressed genes (DEGs) were identified at each time point by comparing the hepatic transcriptome of mice fed HFD with that of mice fed normal diet. Next, we clustered the union of DEGs and identified annotations related to each cluster. Finally, we constructed an 'integrated obesity-associated gene regulatory network (GRN) in murine liver'. We analyzed the epididymal white adipose tissue (eWAT) transcriptome usig the same procedure.

RESULTS

Based on time-course microarray data, we found that the genes associated with immune responses were upregulated with an oscillating expression pattern between weeks 2 and 8, relatively downregulated between weeks 12 and 16, and eventually upregulated after week 20 in the liver of the mice fed HFD. The genes associated with immune responses were also upregulated at late stage, in the eWAT of the mice fed HFD. These results suggested that a critical transition occurred in the immune system-related transcriptomes of the liver and eWAT around week 16 of the DIO development, and this may be associated with the delayed pathological alterations. The GRN analysis suggested that Maff may be a key transcription factor for the immune system-related critical transition thatoccurred at week 16. We found that transcription factors associated with immune responses were centrally located in the integrated obesity-associated GRN in the liver.

CONCLUSIONS

In this study, systems analysis identified regulatory network modules underlying the delayed immune system-related pathological changes during the development of DIO and could suggest possible therapeutic targets.

Involuntary wheel running improves but does not fully reverse the deterioration of bone structure of obese rats despite decreasing adiposity

This study investigated whether exercise or antioxidant supplementation with vitamin C and E during exercise affects bone structure and markers of bone metabolism in obese rat. Sprague-Dawley rats, 6-week old, were fed a normal-fat diet (NF, 10 % kcal as fat) and a high-fat diet (HF, 45 % with extra fat from lard) ad libitum for 14 weeks. Then, rats on the high-fat diet were assigned randomly to three treatment groups for additional 12 weeks with forced exercise: HF; HF + exercise (HF + Ex); and HF with vitamin C (0.5 g ascorbate/kg diet) and vitamin E (0.4 g α-tocopherol acetate/kg diet) supplementation + exercise (HF + Ex + VCE). At the end of the study, body weight and fat (%) were similar among NF, HF + Ex, and HF + Ex + VCE, whereas HF had greater body weight and fat (%) than other groups. Compared to NF, HF had elevated serum leptin, tartrate-resistant acid phosphatase (TRAP), and IGF-1; increased trabecular separation and structural model index; and lowered bone mineral density, trabecular connectivity density, and trabecular number in distal femur, while HF + Ex and HF + Ex + VCE had elevated serum TRAP and decreased bone volume/total volume and trabecular number of distal femurs. Compared to HF, HF + Ex and HF + Ex + VCE had decreased serum TRAP and osteocalcin and improved bone structural properties of the distal femur. These findings suggest that exercise, while decreasing body fat, does not fully protect against the negative skeletal effects of existing obesity induced by a high-fat diet. Furthermore, vitamin C and E supplementation has no additional benefits on bone structural properties during exercise.

Obesity-related changes in bone structural and material properties in hyperphagic OLETF rats and protection by voluntary wheel running

PURPOSE

To examine how the development of obesity and the associated insulin resistance affect bone structural and material properties, and bone formation and resorption markers in the Otsuka Long-Evans Tokushima Fatty (OLETF) rat model.

METHODS

This was a 36-week study of sedentary, hyperphagic, male OLETF rats (OLETF-SED), exercise-treated OLETF rats (OLETF-EX) and sedentary non-hyperphagic controls (LETO-SED) with data collection at 13, 20, and 40 weeks of age (n = 5-8 animals per group per timepoint).

RESULTS

Body mass and fat (%) were significantly greater in OLETF-SED versus controls. OLETF-SED were insulin resistant at 13 and 20 weeks, with overt diabetes by 40 weeks. At 13weeks, OLETF-SED had lower total body BMC and BMD and serum P1NP compared with LETO-SED. Differences in total body BMC and BMD between OLETF-SED and LETO-SED persisted at 20 weeks, with reductions in total and cortical BMD of the tibia. OLETF-SED also had lesser femur diameter, cross-sectional area, polar moment of area, and torque at fracture than LETO-SED. By 40 weeks, OLETF-SED had elevated bone resorption and reduced intrinsic bone strength. OLETF-EX did not show the excessive weight gain, obesity, insulin resistance or diabetes observed in OLETF-SED. OLETF-EX had greater BMD than OLETF-SED, and structural and material properties of the femur were significantly increased in OLETF-EX relative to OLETF-SED and LETO-SED.

CONCLUSIONS

The negative skeletal effects of excessive adiposity and insulin resistance were evident early in the progressive obesity with lasting negative impacts on intrinsic and extrinsic bone strength. Exercise protected against obesity-associated skeletal changes with marked benefits on the biomechanical properties of bone.

Effect of weight loss on bone health in overweight/obese postmenopausal breast cancer survivors

Current guidelines recommend weight loss in obese cancer survivors. Weight loss, however, has adverse effects on bone health in obese individuals without cancer but this has not been evaluated in breast cancer survivors. We investigated the associations of intentional weight loss with bone mineral density (BMD) and bone turn-over markers in overweight/obese postmenopausal breast cancer survivors. Participants were overweight/obese breast cancer survivors (N = 81) with stage I, II or IIIA disease enrolled in the St. Louis site of a multi-site Exercise and Nutrition to Enhance Recovery and Good health for You (ENERGY) study; a randomized-controlled clinical trial designed to achieve a sustained ≥7 % loss in body weight at 2 years. Weight loss was achieved through dietary modification with the addition of physical activity. Generalized estimating equations were used to assess differences in mean values between follow-up and baseline. Mean weight decreased by 3 and 2.3 % between baseline and 6-month follow-up, and 12-month follow-up, respectively. There were decreases in osteocalcin (10.6 %, p value < 0.001), PINP (14.5 %, p value < 0.001), NTx (19.2 % p value < 0.001), and RANK (48.5 %, p value < 0.001), but not BALP and CTX-1 levels between baseline and 12-month follow-up. No significant changes occurred in mean T-scores, pelvis and lumbar spine BMD between baseline and 12-month follow-up. A 2.3 % weight loss over 12 months among overweight/obese women with early-stage breast cancer does not appear to have deleterious effect on bone health, and might even have beneficial effect. These findings warrant confirmation, particularly among breast cancer survivors with a larger magnitude of weight loss.

Positive Association Between Adipose Tissue and Bone Stiffness

Obesity is often considered to have a protective effect against osteoporosis. On the other hand, several recent studies suggest that adipose tissue may have detrimental effects on bone quality. We therefore aimed to investigate the associations between body mass index (BMI), waist circumference (WC), visceral adipose tissue (VAT) or abdominal subcutaneous adipose tissue (SAT), and bone stiffness. The study involved 2685 German adults aged 20-79 years, who participated in either the second follow-up of the population-based Study of Health in Pomerania (SHIP-2) or the baseline examination of the SHIP-Trend cohort. VAT and abdominal SAT were quantified by magnetic resonance imaging. Bone stiffness was assessed by quantitative ultrasound (QUS) at the heel (Achilles InSight, GE Healthcare). The individual risk for osteoporotic fractures was determined based on the QUS-derived stiffness index and classified in low, medium, and high risk. Linear regression models, adjusted for sex, age, physical activity, smoking status, risky alcohol consumption, diabetes, and height (in models with VAT or abdominal SAT as exposure), revealed positive associations between BMI, WC, VAT or abdominal SAT, and the QUS variables broadband-ultrasound attenuation or stiffness index. Moreover, BMI was positively associated with speed of sound. Our study shows that all anthropometric measures including BMI and, WC as well as abdominal fat volume are positively associated with bone stiffness in the general population. As potential predictors of bone stiffness, VAT and abdominal SAT are not superior to easily available measures like BMI or WC.

Obesity in the Context of Aging: Quality of Life Considerations

The progressive increase in the prevalence of obesity and aging in the population is resulting in increased healthcare and disability spending. The burden of obesity is particularly relevant in old age, due to accumulating co-morbidities and changes in body composition. Sarcopenic obesity, a mix of over- and under-nutrition, causes frailty, disability, and problems in social and psychological areas, impacting overall health-related quality of life (HR-QOL). The relationship between obesity, aging, and HR-QOL is, however, much more complex than generally acknowledged and is difficult to disentangle. The impact of obesity on HR-QOL is particularly strong in young people, who are free of co-morbidities. It progressively attenuates, compared with the general population, with advancing age, when co-morbid conditions are diffusely present and reduce the perceived health status, independent of obesity. However, even this apparent 'obesity paradox' should not minimize the importance of obesity on HR-QOL, as other obesity-associated limitations and disabilities do impact HR-QOL in older age. A patient-centered approach aimed at reducing the disability and social isolation of advancing age is mandatory to improve HR-QOL in any class of obesity.

Association between low C-peptide and low lumbar bone mineral density in postmenopausal women without diabetes

In this population-based, cross-sectional study in Italian postmenopausal females not affected by diabetes, we showed a link between serum C-peptide and lumbar bone mineral density, suggesting that C-peptide exerts an insulin-independent effect on bone mass.

INTRODUCTION

It is well known that type 1 (T1) diabetes, characterized by insulin and C-peptide deficiency, is associated with a low lumbar bone mineral density and an increased risk for fracture. While a role for insulin in the pathogenesis of osteoporosis has been demonstrated, the association between C-peptide and the bone mineral density has not been investigated. We conducted a study in a cohort of 84 postmenopausal women without diabetes to clarify the association between serum C-peptide and the lumbar bone mineral density.

METHODS

Participants underwent a bone mineral density evaluation by DXA and biochemical analysis including the C-peptide assay.

RESULTS

rteen percent of the population had osteoporosis and 38% had osteopenia. With ANOVA test, we showed that women with the lowest C-peptide concentration had lower lumbar mineral density in comparison to those in all other C-peptide concentration group (p = 0.02 among groups after adjustment). The univariate and multivariate analysis showed that C-peptide was positively associated with both lumbar T-score and Z-score besides other well-known factors like age (with T-score p < 0.001; beta = -0.38) and BMI (with T-score p = 0.009; beta = 0.34), while insulin was not correlated with the lumbar bone mineral density. The area under the receiver operating characteristic (ROC) curve for C-peptide to predict the absence of lumbar osteoporosis was 0.74 (SE = 0.073; p = 0.013).

CONCLUSIONS

These results suggest that C-peptide may exert an insulin- and BMI-independent effect on lumbar bone mineral density and that further large-scale studies are needed in order to clarify its role in bone mineralization especially in subjects without diabetes.

Regional variability in changes in the incidence of hip fracture in the Spanish population (2000-2012)

The objective is to analyse the evolution of the incidence of hip fracture in the female population of Spain from 2000 to 2012 and to establish the possible changes which may have been seen over this period of time, including the trends in the different regions of the country.

INTRODUCTION

Fragility-related hip fractures are considered to be the fractures of greatest significance to public health due to their high degree of morbidity and mortality. The change in their incidence, both in absolute values and when adjusted for age, is the subject of debate. The objective of this article is to describe the changes in the rates of hip fracture in Spain by autonomous community between the years 2000 and 2012.

METHODS

Using the data from the Spanish Minimum Basic Data Set, in which are all the recorded cases of women with a principal diagnosis of hip fracture, the incidence rates by age group and by autonomous community were obtained. Poisson distribution or negative binomial regressions were carried out to estimate the average annual change over the time period analysed.

RESULTS

There have been statistically significant changes in the trends of rates of incidence for all age groups of women over 65 years of age. The annual reduction was 2.2% for women of 65-74 years of age and less for those between 75 and 84. The rates of incidence for those over 85 increased annually by 0.58%.

CONCLUSIONS

Hip fractures continue to increase in absolute numbers, although if the rates are adjusted for age, a downward trend is seen in certain age groups. These findings have various origins, although in the absence of great changes in population structure, we believe that drug treatments for osteoporosis may play a role. There is variability in the change in incidence of hip fractures in different parts of the country. Further studies are required to be able to identify the causes.

Parathyroid hormone, calcium, and sodium bridging between osteoporosis and hypertension in postmenopausal Korean women

The coexistence of osteoporosis and hypertension, which are considered distinct diseases, has been widely reported. In addition, daily intake of calcium and sodium, as well as parathyroid hormone levels (PTH), is known to be associated with osteoporosis and hypertension. This study aimed to determine the association of low calcium intake, high sodium intake, and PTH levels with osteoporosis and hypertension in postmenopausal Korean women. Data for postmenopausal Korean women aged 50 years or older were obtained from the Korea National Health and Nutrition Examination Survey 2008-2011. Osteoporosis was diagnosed using dual energy X-ray absorptiometry, while hypertension was diagnosed using blood pressure data. The odds ratios for osteoporosis and hypertension were calculated using logistic regression analysis for quartiles of the daily calcium intake, daily sodium intake, and PTH levels. Women with hypertension had a high coexistence of osteoporosis (43.6 vs. 36.5 %; P = 0.022), and vice versa (21.1 vs. 16.6 %; P = 0.022). PTH was significantly associated with osteoporosis and hypertension, and a high intake of calcium was strongly correlated with a low incidence of osteoporosis. This is the first study to report the characteristics of postmenopausal Korean women who have high dietary sodium intake and low dietary calcium intake, in association with the incidence of osteoporosis and hypertension. Osteoporosis and hypertension were strongly associated with each other, and PTH appears to be a key mediator of both diseases, suggesting a possible pathogenic link.

Complex association between body weight and fracture risk in postmenopausal women

Osteoporosis is a common disease, characterized by low bone mass with micro-architectural disruption and skeletal fragility, resulting in an increased risk of fracture. A substantial number of studies has examined the possible relationship between body weight, bone mineral density and fracture risk in post-menopausal women, with the majority of them concluding that low body weight correlates with increased risk of fracture, especially hip fracture. Controversies about the potential protective effect of obesity on osteoporosis and consequent fracture risk still exist. Several recent studies question the concept that obesity exerts a protective effect against fractures, suggesting that it stands as a risk factor for fractures at specific skeletal sites, such as upper arm. The association between body weight and fracture risk is complex, differs across skeletal sites and body mass index, and is modified by the interaction between body weight and bone mineral density. Some potential explanations that link obesity with increased fracture risk may be the pattern of falls and impaired mobility in obese individuals, comorbidities, such as asthma, diabetes and early menopause, as well as, increased parathyroid hormone and reduced 25-hydroxy-vitamin D concentrations.

Abdominal obesity increases the risk of hip fracture. A population-based study of 43,000 women and men aged 60-79 years followed for 8 years. Cohort of Norway

BACKGROUND

The question as to whether abdominal obesity has an adverse effect on hip fracture remains unanswered. The purpose of this study was to investigate the associations of waist circumference, hip circumference, waist-hip ratio, and body mass index with incident hip fracture.

METHODS

The data in this prospective study is based on Cohort of Norway, a population-based cohort established during 1994-2003. Altogether 19,918 women and 23,061 men aged 60-79 years were followed for a median of 8.1 years. Height, weight, waist and hip circumference were measured at baseline using standard procedures. Information on covariates was collected by questionnaires. Hip fractures (n = 1,498 in women, n = 889 in men) were identified from electronic discharge registers from all general hospitals in Norway between 1994 and 2008.

RESULTS

The risk of hip fracture decreased with increasing body mass index, plateauing in obese men. However, higher waist circumference and higher waist-hip ratio were associated with an increased risk of hip fracture after adjustment for body mass index and other potential confounders. Women in the highest tertile of waist circumference had an 86% (95% CI: 51-129%) higher risk of hip fracture compared to the lowest, with a corresponding increased risk in men of 100% (95% CI 53-161%). Lower body mass index combined with abdominal obesity increased the risk of hip fracture considerably, particularly in men.

CONCLUSION

Abdominal obesity was associated with an increased risk of hip fracture when body mass index was taken into account. In view of the increasing prevalence of obesity and the number of older people suffering osteoporotic fractures in Western societies, our findings have important clinical and public health implications.

Effect of ibandronate therapy on serum homocysteine and leptin in postmenopausal osteoporotic females

A significant change in serum leptin level and no change in homocysteine were observed with ibandronate treatment. No correlation of homocysteine and leptin was found with bone mass density (BMD). Results indicate that ibandronate reduces serum leptin levels but how does it help in reducing the osteoporosis. It needs to be explored.

INTRODUCTION

The current study was planned to determine the effects of ibandronate on serum homocysteine and leptin levels in postmenopausal osteoporotic females and to correlate these with BMD.

METHODS

Forty-two newly diagnosed and untreated postmenopausal osteoporotic females were selected on the basis of their BMD (BMD < -2.5) from Orthopaedic Out Patient Department of Shaikh Zayed Hospital, Lahore, Pakistan, and 36, age and BMI matched non-osteoporotic postmenopausal females, were also selected as a control group. Baseline physical and biochemical parameters were compared. In osteoporotic patients, changes in circulating leptin and homocysteine levels were studied after 6 months of therapy with ibandronate (150 mg). The collected data were analyzed on SPSS 16.

RESULTS

There was no significant difference observed in the mean value of all baseline parameters except BMD in both groups. After 6 months of treatment with ibandronate (150 mg), a significant change was observed in serum leptin levels (19.48 ± 1.60 ng/ml vs. 14.09 ± 0.85 ng/ml, p < 0.002), while no considerable change observed in serum homocysteine levels (16.22 ± 0.95 μmol/l vs. 16.80 ± 1.03 μmol/l, p < 0.63). Serum leptin was found significantly correlated with anthropometric parameters. No correlation of serum leptin and homocysteine was found with BMD (r = 0.09, p value = 0.54; r = -0.17, p value = 0.27).

CONCLUSION

Our results show that ibandronate reduces serum leptin levels while it has no effect on serum homocysteine levels. Further studies are needed to explain how the decrease in serum leptin level may help in reducing the progression of osteoporosis.

Biomineralized matrices dominate soluble cues to direct osteogenic differentiation of human mesenchymal stem cells through adenosine signaling

Stem cell differentiation is determined by a repertoire of signals from its microenvironment, which includes the extracellular matrix (ECM) and soluble cues. The ability of mesenchymal stem cells (MSCs), a common precursor for the skeletal system, to differentiate into osteoblasts and adipocytes in response to their local cues plays an important role in skeletal tissue regeneration and homeostasis. In this study, we investigated whether a bone-specific calcium phosphate (CaP) mineral environment could induce osteogenic differentiation of human MSCs, while inhibiting their adipogenic differentiation, in the presence of adipogenic-inducing medium. We also examined the mechanism through which the mineralized matrix suppresses adipogenesis of hMSCs to promote their osteogenic differentiation. Our results show that hMSCs cultured on mineralized matrices underwent osteogenic differentiation despite being cultured in the presence of adipogenic medium, which indicates the dominance of matrix-based cues of the mineralized matrix in directing osteogenic commitment of stem cells. Furthermore, the mineralized matrix-driven attenuation of adipogenesis was reversed with the inhibition of A2b adenosine receptor (A2bR), implicating a role of adenosine signaling in mineralized environment-mediated inhibition of adipogenesis. Such synthetic matrices with an intrinsic ability to direct differentiation of multipotent adult stem cells toward a targeted phenotype while inhibiting their differentiation into other lineages not only will be a powerful tool in delineating the role of complex microenvironmental cues on stem cell commitment but also will contribute to functional tissue engineering and their translational applications.

Soy protein isolate inhibits high-fat diet-induced senescence pathways in osteoblasts to maintain bone acquisition in male rats

Chronic consumption by experimental animals of a typical Western diet high in saturated fats and cholesterol during postnatal life has been demonstrated to impair skeletal development. However, the underlying mechanism by which high-fat, energy-dense diets affect bone-forming cell phenotypes is poorly understood. Here, we show that male weanling rats fed a diet containing 45% fat and 0.5% cholesterol made with casein (HF-Cas) for 6 weeks displayed lower bone mineral density and strength compared with those of AIN-93G-fed dietary controls. Substitution of casein with soy protein isolate (SPI) in the high-fat diet (HF-SPI) prevented these effects. The bone-sparing effects of SPI were associated with prevention of HF-Cas-induced osteoblast senescence pathways through suppression of the p53/p21 signaling pathways. HF-Cas-fed rats had increased caveolin-1 and down-regulated Sirt1, leading to activations of peroxisome proliferator-activated receptor γ (PPARγ) and p53/p21, whereas rats fed HF-SPI suppressed caveolin-1 and activated Sirt1 to deacetylate PPARγ and p53 in bone. Treatment of osteoblastic cells with nonesterified free fatty acid (NEFA) increased cell senescence signaling pathways. Isoflavones significantly blocked activations of senescence-associated β-galactosidase and PPARγ/p53/p21 by NEFA. Finally, replicative senescent osteoblastic cells and bone marrow mesenchymal ST2 cells exhibited behavior similar to that of cells treated with NEFA and in vivo bone cells in rats fed the HF-Cas diet. These results suggest that (1) high concentrations of NEFA occurring with HF intake are mediators of osteoblast cell senescence leading to impairment of bone development and acquisition and (2) the molecular mechanisms underlying the SPI-protective effects involve isoflavone-induced inhibition of osteoblastic cell senescence to prevent HF-induced bone impairments.

Impact of source tissue and ex vivo expansion on the characterization of goat mesenchymal stem cells

BACKGROUND

There is considerable interest in using goats as models for genetically engineering dairy animals and also for using stem cells as therapeutics for bone and cartilage repair. Mesenchymal stem cells (MSCs) have been isolated and characterized from various species, but are poorly characterized in goats.

RESULTS

Goat MSCs isolated from bone marrow (BM-MSCs) and adipose tissue (ASCs) have the ability to undergo osteogenic, adipogenic and chondrogenic differentiation. Cytochemical staining and gene expression analysis show that ASCs have a greater capacity for adipogenic differentiation compared to BM-MSCs and fibroblasts. Different methods of inducing adipogenesis also affect the extent and profile of adipogenic differentiation in MSCs. Goat fibroblasts were not capable of osteogenesis, hence distinguishing them from the MSCs. Goat MSCs and fibroblasts express CD90, CD105, CD73 but not CD45, and exhibit cytoplasmic localization of OCT4 protein. Goat MSCs can be stably transfected by Nucleofection, but, as evidenced by colony-forming efficiency (CFE), yield significantly different levels of progenitor cells that are robust enough to proliferate into colonies of integrants following G418 selection. BM-MSCs expanded over increasing passages in vitro maintained karyotypic stability up to 20 passages in culture, exhibited an increase in adipogenic differentiation and CFE, but showed altered morphology and amenability to genetic modification by selection.

CONCLUSIONS

Our findings provide characterization information on goat MSCs, and show that there can be significant differences between MSCs isolated from different tissues and from within the same tissue. Fibroblasts do not exhibit trilineage differentiation potential at the same capacity as MSCs, making it a more reliable method for distinguishing MSCs from fibroblasts, compared to cell surface marker expression.

Potentiation of osteoclastogenesis by adipogenic conversion of bone marrow-derived mesenchymal stem cells

Bone marrow-derived mesenchymal stem cells (BMSCs) are the indispensable component of the bone marrow, being the common precursors for adipocytes and osteoblasts. We show here that adipogenic differentiation resulted in increase in the production of adipocyte markers, such as adiponectin,fatty-acid binding proteins (FABP4), peroxisome proliferator-activated receptor γ (PPARγ), as well as the receptor activator of nuclear-κB ligand (RANKL). Co-culture of osteoclast precursors (OCPs) with BMSCs-derived adipocytes significantly enhanced osteoclast differentiation with low-dose RANKL, whose levels alone could not promote osteoclastogenesis. These results demonstrate for the first time that adipogenic differentiation of BMSCs plays a pivotal role in maintaining bone homeostasis.

Associations between fat distribution and volumetric bone mineral density in Chinese adults

The aim of this study was to explore the association between fat distribution and volumetric bone mineral density (vBMD) in Chinese Adults. Using a cross-sectional investigation of 867 participants including 521 women and 346 men from China, vBMD and subcutaneous adipose tissue (SCAT) or visceral adipose tissue (VAT) were measured accordingly by quantitative computed tomography. The peak vBMD values of the spine were observed at ages 30-39 years in women and at ages 20-29 years in men. In women, the peak values of VAT and SCAT were observed, respectively, at ages ≥ 70 years and at the age range of 60-69 years. In men, the peak values of VAT and SCAT were observed, respectively, at ages ≥ 70 years and at ages 30-39 years. Using the correlation tests, there was no correlation between SCAT and vBMD in both genders. Most relationships between VAT and BMD were negative (r = -0.204, P < 0.01, in premenopausal women; r = -0.150, P < 0.05, in postmenopausal women; and r = -0.181, P < 0.05, in middle-aged men). After multiple linear regression analysis, no correlations were observed. There appears to be no correlation between fat distribution and vBMD in Chinese adults, and further studies are needed to explore associations between fat distribution and vBMD.

Osteopetrosis in obese female rats is site-specifically inhibited by physical training

NEW FINDINGS

What is the central question of this study? Clinical studies suggest that obesity 'protects' against osteoporosis. However, these studies used only bone densitometry and assessed only one bone site, which is insufficient to enable conclusions to be drawn about the response of the whole skeleton. Furthermore, the effects of exercise on bone responses in obesity have not been explored previously. What is the main finding and what is its importance? We show that obesity causes osteopetrosis. Therefore, the classical perspective of 'protective effects of obesity' needs to be reviewed, and exercise is an important tool to avoid these alterations and to maintain the homeostasis of bone. A sedentary lifestyle and obesity induce systemic inflammatory responses. Although the effects of physical inactivity on osseous tissue have been well established, the effects of obesity on bone tissue remain controversial. Furthermore, the effects of physical training on bone tissue responses in the presence of diet-induced obesity are unknown. Our aim was to investigate the effects of obesity and physical training at multiple bone sites in rats. Female Wistar rats were divided into the following four groups: (i) control diet, non-trained (C-NT); (ii) high-refined carbohydrate-containing diet, non-trained (HC-NT); (iii) control diet, trained (C-T); and (iv) high-refined carbohydrate-containing diet, trained (HC-T). At 5 months of age, the rats were submitted to daily exercise for 30 min day(-1). After 13 weeks, blood samples, adipose and skeletal tissues were harvested. Two-way ANOVA was applied to detect differences (significance accepted when P ≤ 0.05). The HC-NT group exhibited increased body mass, adiposity, serum leptin, serum insulin, insulin resistance index and concentrations of tumour necrosis factor-α and interleukin-6. Obese rats (HC-NT) exhibited thickening of nasal bones, trabecular bones in the lumbar vertebrae and long bones in a site-dependent manner. The HC-T group exhibited similar adiposity and inflammatory results. Morphological analysis of the lumbar vertebrae in rats fed the HC diet revealed characteristics of osteopetrosis that were inhibited by exercise. In conclusion, the HC diet induced obesity and inflammatory/hormonal alterations and increased the trabecular bone in a site-dependent manner. However, obesity caused osteopetrosis in the lumbar vertebrae, which could be inhibited by physical training. Although exercise inhibited the development of bone alterations, physical training did not inhibit the HC diet-induced obesity responses.

The osteogenic or adipogenic lineage commitment of human mesenchymal stem cells is determined by protein kinase C delta

BACKGROUND

Mesenchymal stem cells (MSCs) have the potential to differentiate into specialized cell lineages such as osteoblasts and adipocytes in vitro. There exists a reciprocal relationship between osteogenic and adipogenic differentiation of MSCs that an osteogenic phenotype occurs at the expense of an adipogenic phenotype and vice versa, which in turn influence one another's phenotype through negative feedback loops. Thus, it is important to understand what signaling molecules modulate the lineage commitment of MSCs. Protein kinase C (PKC) plays a central role in cellular signal transduction for mediating diverse biological functions, and dysregulation of PKC activity is involved in various metabolic diseases including cancer, diabetes, and heart disease. Although the role of individual PKC isoforms has been investigated in various fields, the potential role of PKC in bone metabolism is not completely understood. In this study, we investigated the potential role of PKCδ in osteogenic lineage commitment of human bone marrow-derived mesenchymal stem cells (hBMSCs).

RESULTS

We observed that expression and phosphorylation of PKCδ were increased during osteogenic differentiation of hBMSCs. Pharmacological inhibition and genetic ablation of PKCδ in hBMSCs resulted in a significant attenuation of osteogenic differentiation as evidenced by reduced ALP activity and ECM mineralization, as well as down-regulation of the expression of osteoblast-specific genes. These effects were also accompanied by induction of adipogenic differentiation and up-regulation of the expression of adipocyte-specific genes involved in lipid synthesis in osteogenic induction of hBMSCs. Additionally, the activation of AMPK, which is a key cellular energy sensor, induced osteogenesis of hBMSCs. However, the inhibition of AMPK activity by compound C did not affect the activation of PKCδ at all, indicating that there is no direct correlation between AMPK and PKCδ in osteogenesis of hBMSCs.

CONCLUSIONS

These results suggest that PKCδ is a critical regulator for the balance between osteogenesis and adipogenesis of hBMSCs and thus has a potential novel therapeutic target for the treatment of metabolic bone diseases.

Recent developments in metabolic bone diseases: a gnathic perspective

Metabolic bone diseases often are asymptomatic and progress sub clinically. Many patients present at a late stage with catastrophic skeletal and extra skeletal complications. In this article, we provide an overview of normal bone remodeling and a synopsis of recent developments in the following conditions: osteoporosis, rickets/osteomalacia, endocrine-induced bone disease, chronic kidney disease-mineral bone disorder and Paget's disease of bone. Our discussion will emphasize the clinical and microscopic manifestations of these diseases in the jaws.

Relationship between body mass index and fracture risk is mediated by bone mineral density

The relationship between body mass index (BMI) and fracture risk is controversial. We sought to investigate the effect of collinearity between BMI and bone mineral density (BMD) on fracture risk, and to estimate the direct and indirect effect of BMI on fracture with BMD being the mediator. The study involved 2199 women and 1351 men aged 60 years or older. BMI was derived from baseline weight and height. Femoral neck BMD was measured by dual-energy X-ray absorptiometry (DXA; GE-LUNAR, Madison, WI, USA). The incidence of fragility fracture was ascertained by X-ray reports from 1991 through 2012. Causal mediation analysis was used to assess the mediated effect of BMD on the BMI-fracture relationship. Overall, 774 women (35% of total women) and 258 men (19%) had sustained a fracture. Approximately 21% of women and 20% of men were considered obese (BMI ≥ 30). In univariate analysis, greater BMI was associated with reduced fracture risk in women (hazard ratio [HR] 0.92; 95% confidence interval [CI], 0.85 to 0.99) and in men (HR 0.77; 95% CI, 0.67 to 0.88). After adjusting for femoral neck BMD, higher BMI was associated with greater risk of fracture in women (HR 1.21; 95% CI, 1.11 to 1.31) but not in men (HR 0.96; 95% CI, 0.83 to 1.11). Collinearity had minimal impact on the BMD-adjusted results (variance inflation factor [VIF] = 1.2 for men and women). However, in mediation analysis, it was found that the majority of BMI effect on fracture risk was mediated by femoral neck BMD. The overall mediated effect estimates were -0.048 (95% CI, -0.059 to -0.036; p < 0.001) in women and -0.030 (95% CI, -0.042 to -0.018; p < 0.001) in men. These analyses suggest that there is no significant direct effect of BMI on fracture, and that the observed association between BMI and fracture risk is mediated by femoral neck BMD in both men and women.

New insight into fat, muscle and bone relationship in women: determining the threshold at which body fat assumes negative relationship with bone mineral density

BACKGROUND

The aim was to investigate the relationships among lean mass (LM), fat mass (FM), and bone mineral density (BMD) in women stratified by body mass index (BMI) (BMI - normal-weight, overweight, obese) and to determine threshold at which body fat assumes negative relationship with BMD.

METHODS

This was a cross-sectional study in 471 healthy Caucasian women, aged 18-67 years. BMD, LM, and FM were measured using dual-energy X-ray absorptiometry. Analysis of variance with Bonferroni corrections was used to test the BMI group differences. Linear regression was used to examine independent contributions of LM and FM on BMD of various skeletal sites (controlling for age and height). In overweight/obese women PROC LOESS plots were used to determine the inflection points at which either LM or FM relationship with BMD changes direction. Separate analyses in pre- and post-menopausal women were conducted as well.

RESULTS

Spine and femoral neck BMD were not different among three BMI groups while total body, femur and radius BMD were statistically different (the highest in the obese group). Linear regression revealed that LM had significant positive association with BMD of various skeletal sites in all groups. FM showed a negative association with BMD of femoral neck and femur in normal-weight and spine in overweight women, but a positive association with radius in obese women. Inflection points showed that body fat between 33% and 38% assumed negative relationship with BMD for most skeletal sites in overweight and obese women.

CONCLUSIONS

Although LM has strong positive relationship with BMD, FM above 33% in overweight/obese women is negatively related to BMD of most skeletal sites. Therefore, overweight/obesity after certain amount of FM, may not be a protective factor against osteoporosis in females. For clinical practice in women, it is important to maintain LM and keep FM accrual below ~30% body fat to maintain good skeletal health.

Genome-wide QTL mapping of nine body composition and bone mineral density traits in pigs

Background

Since the pig is one of the most important livestock animals worldwide, mapping loci that are associated with economically important traits and/or traits that influence animal welfare is extremely relevant for efficient future pig breeding. Therefore, the purpose of this study was a genome-wide mapping of quantitative trait loci (QTL) associated with nine body composition and bone mineral traits: absolute (Fat, Lean) and percentage (FatPC, LeanPC) fat and lean mass, live weight (Weight), soft tissue X-ray attenuation coefficient (R), absolute (BMC) and percentage (BMCPC) bone mineral content and bone mineral density (BMD).

Methods

Data on the nine traits investigated were obtained by Dual-energy X-ray absorptiometry for 551 pigs that were between 160 and 200 days old. In addition, all pigs were genotyped using Illumina’s PorcineSNP60 Genotyping BeadChip. Based on these data, a genome-wide combined linkage and linkage disequilibrium analysis was conducted. Thus, we used 44 611 sliding windows that each consisted of 20 adjacent single nucleotide polymorphisms (SNPs). For the middle of each sliding window a variance component analysis was carried out using ASReml. The underlying mixed linear model included random QTL and polygenic effects, with fixed effects of sex, housing, season and age.

Results

Using a Bonferroni-corrected genome-wide significance threshold of P < 0.001, significant peaks were identified for all traits except BMCPC. Overall, we identified 72 QTL on 16 chromosomes, of which 24 were significantly associated with one trait only and the remaining with more than one trait. For example, a QTL on chromosome 2 included the highest peak across the genome for four traits (Fat, FatPC, LeanPC and R). The nearby gene, ZNF608, is known to be associated with body mass index in humans and involved in starvation in Drosophila, which makes it an extremely good candidate gene for this QTL.

Conclusions

Our QTL mapping approach identified 72 QTL, some of which confirmed results of previous studies in pigs. However, we also detected significant associations that have not been published before and were able to identify a number of new and promising candidate genes, such as ZNF608.

Electronic supplementary material

The online version of this article (doi:10.1186/s12711-014-0068-2) contains supplementary material, which is available to authorized users.

Effect of Salicornia herbacea on osteoblastogenesis and adipogenesis in vitro

Bone-related complications are among the highest concerning metabolic diseases in the modern world. Bone fragility and susceptibility to fracture increase with age and diseases like osteoporosis. Elevated adipogenesis in bone results in osteoporosis and loss of bone mass when coupled with lack of osteoblastogenesis. In this study the potential effect of Salicornia herbacea extract against osteoporotic conditions was evaluated. Adipogenesis inhibitory effect of S.herbacea has been evidenced by decreased lipid accumulation of differentiating cells and expression levels of crucial adipogenesis markers in 3T3-L1 pre-adipocytes. S.herbacea treatment reduced the lipid accumulation by 25% of the control. In addition, mRNA expression of peroxisome proliferator-activated receptor (PPAR)γ, CCAAT/enhancer-binding protein (C/EBP)α and sterol regulatory element binding protein (SREBP)1c were inhibited by the presence of S. herbacea. Bone formation enhancement effect of S.herbacea was also confirmed in MC3T3-E1 pre-osteoblasts. The presence of S. herbacea significantly elevated the alkaline phosphatase (ALP) activity by 120% at a concentration of 100 μg/mL in differentiating osteoblasts. S. herbacea also significantly increased the expression of osteoblastogenesis indicators, ALP, bone morphogenetic protein (BMP)-2, osteocalcin and collagen type I (collagen-I). In conclusion, S. herbacea possess potential to be utilized as a source of anti-osteoporotic agent that can inhibit adipogenesis while promoting osteoblastogenesis.

Gender-specific associations of appendicular muscle mass with BMD in elderly Italian subjects

Currently used diagnostic measures for sarcopenia are based on the evaluation of appendicular skeletal muscle mass (ASMM) divided by height-squared (ASMMI). This study aimed to investigate the associations between different operational definitions of appendicular muscle mass and BMD at different skeletal sites in aging Italian men and women. In 1199 consecutive healthy Italian subjects, aged 55 years or more (854 women, age 64.2 ± 6.4 years and 165 men, age 65.3 ± 6.1 years), we measured BMD at the lumbar spine (LS-BMD), at femoral neck (FN-BMD),at total hip (TH-BMD), at total body (WB-BMD) and at the right hand (H-BMD) and body composition parameters [ASMM, ASMMI, ASMM/Weight, total lean mass and total fat mass by DXA]. In all subjects, we also measured sex hormones, 25-hydroxyvitamin D and bone turnover markers. In men, both ASMM and ASMMI were positively correlated with BMD at all sites, whereas in women, ASMM and ASMMI did not show any significant correlation with BMD. In men, multiple regression analyses showed that ASMM was positively associated (p < 0.01) with FN-BMD, TH-BMD and H-BMD; however, these associations were no longer present when lean mass was included. In women, both fat mass and lean mass were found positively associated with BMD at all sites. In conclusion, among the different operational measures of the ASMM, only ASMM was significantly associated with BMD in elderly men, but not in elderly women.

Weight loss and bone mineral density

PURPOSE OF REVIEW

Despite evidence that energy deficit produces multiple physiological and metabolic benefits, clinicians are often reluctant to prescribe weight loss in older individuals or those with low bone mineral density (BMD), fearing BMD will be decreased. Confusion exists concerning the effects that weight loss has on bone health.

RECENT FINDINGS

Bone density is more closely associated with lean mass than total body mass and fat mass. Although rapid or large weight loss is often associated with loss of bone density, slower or smaller weight loss is much less apt to adversely affect BMD, especially when it is accompanied with high intensity resistance and/or impact loading training. Maintenance of calcium and vitamin D intake seems to positively affect BMD during weight loss. Although dual energy X-ray absorptiometry is normally used to evaluate bone density, it may overestimate BMD loss following massive weight loss. Volumetric quantitative computed tomography may be more accurate for tracking bone density changes following large weight loss.

SUMMARY

Moderate weight loss does not necessarily compromise bone health, especially when exercise training is involved. Training strategies that include heavy resistance training and high impact loading that occur with jump training may be especially productive in maintaining, or even increasing bone density with weight loss.

Divergent effects of obesity on fragility fractures

Obesity was commonly thought to be advantageous for maintaining healthy bones due to the higher bone mineral density observed in overweight individuals. However, several recent studies have challenged the widespread belief that obesity is protective against fracture and have suggested that obesity is a risk factor for certain fractures. The effect of obesity on fracture risk is site-dependent, the risk being increased for some fractures (humerus, ankle, upper arm) and decreased for others (hip, pelvis, wrist). Moreover, the relationship between obesity and fracture may also vary by sex, age, and ethnicity. Risk factors for fracture in obese individuals appear to be similar to those in nonobese populations, although patterns of falling are particularly important in the obese. Research is needed to determine if and how visceral fat and metabolic complications of obesity (type 2 diabetes mellitus, insulin resistance, chronic inflammation, etc) are causally associated with bone status and fragility fracture risk. Vitamin D deficiency and hypogonadism may also influence fracture risk in obese individuals. Fracture algorithms such as FRAX^® might be expected to underestimate fracture probability. Studies specifically designed to evaluate the antifracture efficacy of different drugs in obese patients are not available; however, literature data may suggest that in obese patients higher doses of the bisphosphonates might be required in order to maintain efficacy against nonvertebral fractures. Therefore, the search for better methods for the identification of fragility fracture risk in the growing population of adult and elderly subjects with obesity might be considered a clinical priority which could improve the prevention of fracture in obese individuals.

Prevalence of fracture and osteoporosis risk factors in American Indian and Alaska Native people

OBJECTIVE

Little is known about prevalence of osteoporosis risk factors among American Indians and Alaska Natives (AIAN).

METHODS

We included AIAN people (n=8,039) enrolled in the Education and Research Towards Health (EARTH) Study. Prevalence ratios were used to determine cross-sectional associations of risk factors with self-reported bone fractures.

RESULTS

There is a high prevalence of multiple risk factors for osteoporosis in AIAN, although the factors that are associated with past fracture vary by gender and geographical area. In general, women who reported a fracture reported more risk behaviors, more than two medical conditions, and low physical activity. Men with higher BMI were less likely to report a fracture. Smoking history was associated with fracture for both genders, though not significantly in all sub-groups.

CONCLUSION

We prevent a high prevalence of risk factors for osteoporosis for AIAN. Future research for osteoporosis risk reduction and prevention in AIAN people is indicated.