Correction to: CD4 T cell count is positively associated with lumbar spine bone mass in HIV-infected men under the age of 50 years

Two sentences in the Discussion section were incorrect.

Association of blood n-3 fatty acid with bone mass and bone marrow TRAP-5b in the elderly with and without hip fracture

The plasma n-3 fatty acid level was 26.2% lower in patients with osteoporotic hip fracture than in those with osteoarthritis. In all patients, n-3 fatty acid was positively associated with bone mineral density and inversely associated with tartrate-resistant acid phosphatase-5b level in bone marrow aspirates, reflecting the bone microenvironment.

INTRODUCTION

Despite the potential beneficial role of n-3 fatty acid (FA) on bone metabolism, the specific mechanisms underlying these effects in humans remain unclear. Here, we assessed whether the plasma n-3 level, as an objective indicator of its status, is associated with osteoporosis-related phenotypes and bone-related markers in human bone marrow (BM) samples.

METHODS

This was a case-control and cross-sectional study conducted in a clinical unit. n-3 FA in the blood and bone biochemical markers in the BM aspirates were measured by gas chromatography/mass spectrometry and immunoassay, respectively. BM fluids were collected from 72 patients who underwent hip surgery because of either osteoporotic hip fracture (HF; n = 28) or osteoarthritis (n = 44).

RESULTS

After adjusting for confounders, patients with HF had 26.2% lower plasma n-3 levels than those with osteoarthritis (P = 0.006), and each standard deviation increment in plasma n-3 was associated with a multivariate-adjusted odds ratio of 0.40 for osteoporotic HF (P = 0.010). In multivariate analyses including all patients, a higher plasma n-3 level was associated with higher bone mass at the lumbar spine (β = 0.615, P = 0.002) and total femur (β = 0.244, P = 0.045). Interestingly, the plasma n-3 level was inversely associated with the tartrate-resistant acid phosphatase-5b level (β = - 0.633, P = 0.023), but not with the bone-specific alkaline phosphatase level, in BM aspirates.

CONCLUSIONS

These findings provide clinical evidence that n-3 FA is a potential inhibitor of osteoclastogenesis that favors human bone health.

The effects of cortisol and adrenal androgen on bone mass in Asians with and without subclinical hypercortisolism

Analyses using the largest Korean cohort of adrenal incidentaloma (AI) revealed that subtle cortisol excess in premenopausal women and reduced dehydroepiandrosterone-sulfate (DHEA-S) in postmenopausal women and men are associated with bone mineral density (BMD) reduction in Asian patients with subclinical hypercortisolism (SH).

INTRODUCTION

Few studies evaluated bone metabolism in Asians with SH. We investigated associations of cortisol and DHEA-S, an adrenal androgen, with BMD in Asians with AI, with or without SH.

METHODS

We used cross-sectional data of a prospective multicenter study from Korea. We measured BMD, bone turnover markers, cortisol levels after 1-mg dexamethasone suppression test (1-mg DST), DHEA-S, and baseline cortisol to DHEA-S ratio (cort/DHEA-S) in 109 AI patients with SH (18 premenopausal, 38 postmenopausal women, and 53 men) and 686 with non-functional AI (NFAI; 59 premenopausal, 199 postmenopausal women, and 428 men).

RESULTS

Pre- and postmenopausal women, but not men, with SH had lower BMDs at lumbar spine (LS) than those with NFAI (P = 0.008~0.016). Premenopausal women with SH also had lower BMDs at the hip than those with NFAI (P = 0.009~0.012). After adjusting for confounders, cortisol levels after 1-mg DST demonstrated inverse associations with BMDs at all skeletal sites only in premenopausal women (β = - 0.042~- 0.033, P = 0.019~0.040). DHEA-S had positive associations with LS BMD in postmenopausal women (β = 0.096, P = 0.001) and men (β = 0.029, P = 0.038). The cort/DHEA-S had inverse associations with LS BMD in postmenopausal women (β = - 0.081, P = 0.004) and men (β = - 0.029, P = 0.011). These inverse associations of cort/DHEA-S remained significant after adjusting for cortisol levels after 1-mg DST (β = - 0.079~- 0.026, P = 0.006~0.029). In postmenopausal women, the odds ratios of lower BMD by DHEA-S and cort/DHEA-S was 0.26 (95% CI, 0.08-0.82) and 3.40 (95% CI, 1.12-10.33), respectively.

CONCLUSION

Subtle cortisol excess in premenopausal women and reduced DHEA-S in postmenopausal women and men may contribute to BMD reduction in Asians with SH.

The association of cortisol and adrenal androgen with trabecular bone score in patients with adrenal incidentaloma with and without autonomous cortisol secretion

Despite ethnic differences in cortisol sensitivity, only one study in Caucasians has assessed trabecular bone score (TBS) in patients with subclinical hypercortisolism (SH). We showed that both subtle cortisol excess and reduced adrenal androgen may contribute to impaired bone quality in Asian women with SH.

INTRODUCTION

One study in Caucasians has assessed trabecular bone score (TBS), an index of bone microstructure, in adrenal incidentaloma (AI) patients with subclinical hypercortisolism (SH). There are ethnic differences in cortisol sensitivities between Caucasian and Asian populations. We investigated the associations of cortisol and the adrenal androgen dehydroepiandrosterone-sulfate (DHEA-S) with TBS in AI patients with SH, adrenal Cushing's syndrome (CS), and nonfunctional AI (NFAI).

METHODS

We measured TBS, cortisol levels after the overnight 1 mg dexamethasone suppression test (1 mg DST), and cortisol/DHEA-S in 61 patients with SH (30 men; 31 women), 19 with adrenal CS (4 men; 15 women), and 355 with NFAI (213 men; 142 women).

RESULTS

After adjusting for confounders, the serum cortisol level after 1 mg DST was inversely correlated with TBS in men (β = -0.133, P = 0.045) and women (β = - 0.140, P = 0.048). Higher cortisol/DHEA-S ratio was associated with lower TBS in women (β = - 0.252, P < 0.001), but not men. This inverse association of cortisol/DHEA-S ratio in women remained statistically significant after adjusting for the serum cortisol level after 1 mg DST (β = - 0.221, P = 0.008). Compared with women with NFAI, women with SH had 2.2% lower TBS (P = 0.040). Deteriorated bone microstructure (TBS < 1.230) was associated with the serum cortisol level after 1 mg DST (odds ratio [OR], 2.18; 95% confidence interval [CI], 1.04-4.53) and cortisol/DHEA-S ratio (OR, 2.05; 95% CI, 1.03-4.08).

CONCLUSIONS

Subtle cortisol excess in both genders and reduced DHEA-S, especially in women, may contribute to impaired bone quality in Asian patients with SH.

The positive association of total protein intake with femoral neck strength (KNHANES IV)

Data gathered from a nationally representative cohort demonstrate that higher dietary protein intake was positively associated with the composite indices of femoral neck strength in both men and women, suggesting that higher protein intake may contribute to lower risk of hip fracture through the improvement of bone strength.

INTRODUCTION

Despite the general belief that higher protein intake may be helpful for bone homeostasis, its impact on human bone health is still debated. Furthermore, the association of dietary protein intake with femoral neck (FN) strength, which can predict fracture risk independently of bone mineral density (BMD), has not been thoroughly studied.

METHODS

This is a population-based, cross-sectional study from Korea National Health and Nutrition Examination Surveys, including 592 men aged 50 years or older and 590 postmenopausal women. The composite indices of FN strength, such as the compression strength index (CSI), bending strength index (BSI), and impact strength index (ISI), were generated by combining BMD, body weight, and height with the femoral axis length and width, which were measured by dual-energy X-ray absorptiometry.

RESULTS

After adjustment for confounders, total protein intake (g/kg/day) positively correlated with all three FN composite indices in both genders (P = 0.006 to 0.035), except for BSI showing marginal significance in postmenopausal women (P = 0.093). Consistently, compared with subjects in lowest total protein intake quartile, those in the highest quartile showed markedly higher CSI, BSI, and ISI values (P = 0.043 to < 0.001), with a dose-response manner across increasing total protein intake quartile categories in both men and women (P for trend = 0.028 to < 0.001).

CONCLUSIONS

These findings provide the clinical evidence that higher dietary protein intake can play a beneficial role on bone health through the increase of FN strength relative to load in adults.

Association between obesity and femoral neck strength according to age, sex, and fat distribution

Indicators of total and abdominal obesity were negatively associated with femoral neck strength indices. There are age-, sex-, and fat distribution-specific differences in the magnitude of these associations. These suggested that indicators of obesity with different magnitude according to age, sex, and fat distribution associated with poor bone health.

INTRODUCTION

Fat regulates bone metabolism, but the associations of total and abdominal obesity with bone health are inconsistent. We investigated the association between indicators of obesity and composite indices of femoral neck (FN) strength reflecting the risk of hip fracture.

METHODS

This population-based cross-sectional study examined data from the Korea National Health and Nutrition Examination Surveys. Participants were divided into groups according to age (25-49/≥50 years) and sex. We examined total fat mass (TFM) and percentage fat mass (pFM) as indicators of total obesity and truncal fat mass (TrFM) as an indicator of abdominal obesity. We calculated the composite indices of FN strength and anthropometric clinical indicators of abdominal obesity.

RESULTS

TFM, pFM, and TrFM were negatively associated with the composite indices, irrespective of age and sex (P < 0.001-0.005). Most anthropometric clinical indicators of abdominal obesity showed negative associations with the composite indices regardless of age and sex (P < 0.001-0.048), except for women aged 25-49 years. In men, magnitudes of the negative contributions of TFM to the composite indices were significantly stronger at age 25-49 years than at age ≥50 years. Magnitudes of negative associations of TFM with the composite indices were greater in men than in women. TrFM had a more detrimental effect than TFM on FN strength in men aged 25-49 years and in women of both ages.

CONCLUSION

Indicators of total and abdominal obesity negatively associated with FN strength, and magnitudes of their effects on bone health differed according to age, sex, and fat distribution.

Association of circulating dipeptidyl-peptidase 4 levels with osteoporotic fracture in postmenopausal women

Postmenopausal women with osteoporotic fracture (OF) had higher plasma dipeptidyl-peptidase 4 (DPP4) levels than those without. Furthermore, higher plasma DPP4 levels were significantly associated with higher bone turnover and a higher prevalence of OF. These results indicated that DPP4 may be associated with OF by mediating bone turnover rate.

INTRODUCTION

Evidence indicates that dipeptidyl-peptidase 4 (DPP4) plays a distinct role in bone metabolism. However, there has been no report on the association, if any, between circulating DPP4 levels and osteoporosis-related phenotypes, including osteoporotic fracture (OF). Therefore, we performed a case-control study to investigate these associations in postmenopausal women.

METHODS

This study was conducted in multiple centers in Korea. We enrolled 178 cases with OF and 178 age- and body mass index-matched controls. OF was assessed by an interviewer-assisted questionnaire and lateral thoracolumbar radiographs. Bone turnover markers (BTMs), bone mineral density (BMD), and plasma DPP4 levels were obtained in all subjects.

RESULTS

After adjustment for potential confounders, subjects with OF had significantly higher DPP4 levels than those without (P = 0.021). Higher DPP4 levels were significantly positively associated with higher levels of all BTMs, but not with BMD at all measured sites. The differences in DPP4 levels according to OF status disappeared after an additional adjustment for each BTM, but not after adjustment for any BMD values. BTMs explained approximately half of the relationship between DPP4 and OF. The risk of OF was 3.80-fold (95% confidence interval = 1.53-9.42) higher in subjects in the highest DPP4 quartile than in those in the lowest quartile after adjustment for potential confounders, including femoral neck BMD.

CONCLUSIONS

DPP4 may be associated with OF by at least partly mediating the bone turnover rate. Circulating DPP4 levels may be a potential biomarker that could increase the predictive power of current fracture risk assessment models.

The circulating sphingosine-1-phosphate level predicts incident fracture in postmenopausal women: a 3.5-year follow-up observation study

A high level of circulating sphingosine-1-phosphate (S1P) is associated with a high incidence of osteoporotic fracture and a high rate of an insufficient response to bisphosphonate therapy.

INTRODUCTION

Sphingosine-1-phosphate (S1P) is a significant regulator of bone metabolism. Recently, we found that a high plasma S1P level is associated with low bone mineral density (BMD), high levels of bone resorption markers (BRMs), and a high risk of prevalent vertebral fracture in postmenopausal women. We investigated the possibility that S1P is a predictor of incident fracture.

METHODS

A total of 248 postmenopausal women participated in this longitudinal study and were followed up for a mean duration of 3.5 years (untreated [n = 76] or treated with bisphosphonate or hormone replacement therapy [n = 172]). The baseline plasma S1P level and prevalent and incident fracture occurrence were assessed.

RESULTS

A high S1P level was significantly associated with a higher rate of prevalent fracture after adjusting for femoral neck (FN) BMD, BRM, and potential confounders (odds ratio = 2.05; 95 % confidence interval [CI] = 1.03-4.00). Incident fractures occurred more frequently in the highest S1P tertile (T3) than in the lower two tertiles (T1-2) after adjusting for confounders, including baseline FN BMD, prevalent fracture, antiosteoporotic medication, annualized changes in FN BMD, BRM, and potential confounders (hazard ratio = 5.52; 95 % CI = 1.04-56.54). Insufficient response to bisphosphonate therapy occurred more frequently in T3 than T1-2 (odds ratio = 4.43; 95 % CI = 1.02-21.25).

CONCLUSIONS

The plasma S1P level may be a potential predictor of fracture occurrence and an insufficient response to bisphosphonate therapy in postmenopausal women.

The effect of sphingosine-1-phosphate on bone metabolism in humans depends on its plasma/bone marrow gradient

BACKGROUND

Although recent studies provide clinical evidence that sphingosine-1-phosphate (S1P) may primarily affect bone resorption in humans, rather than bone formation or the osteoclast-osteoblast coupling phenomenon, those studies could not determine which bone resorption mechanism is more important, i.e., chemorepulsion of osteoclast precursors via the blood to bone marrow S1P gradient or receptor activator of NF-κB ligand (RANKL) elevation in osteoblasts via local S1P.

AIM

To investigate how S1P mainly contributes to increased bone resorption in humans, we performed this case-control study at a clinical unit in Korea.

METHODS

Blood and bone marrow samples were contemporaneously collected from 70 patients who underwent hip surgery due to either osteoporotic hip fracture (HF) (n = 10) or other causes such as osteoarthritis (n = 60).

RESULTS

After adjusting for sex, age, BMI, smoking, alcohol, previous fracture, diabetes, and stroke, subjects with osteoporotic HF demonstrated a 3.2-fold higher plasma/bone marrow S1P ratio than those without HF, whereas plasma and bone marrow S1P levels were not significantly different between these groups. Consistently, the risk of osteoporotic HF increased 1.38-fold per increment in the plasma/bone marrow S1P ratio in a multivariate adjustment model. However, the odds ratios for prevalent HF according to the increment in the plasma and bone marrow S1P level were not statistically significant.

CONCLUSION

Our current results using simultaneously collected blood and bone marrow samples suggest that the detrimental effects of S1P on bone metabolism in humans may depend on the S1P gradient between the peripheral blood and bone marrow cavity.

Psychosine inhibits osteoclastogenesis and bone resorption via G protein-coupled receptor 65

BACKGROUND

It was recently reported that G protein-coupled receptor 65 (GPR65) suppresses ovariectomy-induced bone loss.

AIM

The present study investigated the role of the lysosphingolipid psychosine, a GPR65 ligand, on osteoclastic differentiation and bone resorption.

METHODS

Osteoclasts were differentiated from mouse bone marrow macrophages. Tartrate-resistant acid phosphatase-positive multinucleated cells were considered to be osteoclasts, and the resorption area was measured by incubating the cells on dentine discs. The expression levels of osteoclast differentiation markers were assessed by qRT-PCR. GPR65 siRNA and its scrambled siRNA were transfected with lipofectamine. Intracellular cyclic adenosine monophosphate (cAMP) levels were assessed using a direct enzyme immunoassay.

RESULTS

Psychosine inhibited osteoclastogenesis and in vitro bone resorption without any significant effect on the viability of pre-osteoclasts, decreased the expression of osteoclast differentiation markers significantly, and increased intracellular cAMP levels. The knockdown of GPR65 by its siRNA restored osteoclastogenesis and decreased cAMP levels in the presence of psychosine.

CONCLUSION

Psychosine inhibits osteoclastogenesis by increasing intracellular cAMP levels via GPR65.

Low skeletal muscle mass associates with low femoral neck strength, especially in older Korean women: the Fourth Korea National Health and Nutrition Examination Survey (KNHANES IV)

SUMMARY

Data gathered from a nationally representative cohort demonstrated that subject with low skeletal muscle mass had consistently low femoral neck composite strength indices for compression, bending, and impact, especially in older women, supporting the highly integrated nature of skeletal muscle and bone.

INTRODUCTION

Skeletal muscle and bone interact mechanically and functionally. The present study was performed to investigate the association between muscle mass and femoral neck composite strength indices using a nationally representative cohort.

METHODS

This is a population-based, cross-sectional study from Korea National Health and Nutrition Examination Surveys, including 1,275 Koreans (674 women and 601 men) aged 50 years or older. Femoral neck axis length and width were measured by hip DXA scans and were combined with BMD, body weight, and height to create composite indices of femoral neck strength relative to load in three different failure modes: compression, bending, and impact. Presarcopenia was defined as an appendicular skeletal muscle mass (ASM) divided by body weight that was less than 1 SD below the sex-specific mean for young adults.

RESULTS

After adjusting for confounders, women with presarcopenia had consistently lower indices for compression strength (CSI), bending strength (BSI), and impact strength (ISI) than women without this condition. Men with presarcopenia had a lower ISI value than men without presarcopenia. Multiple regression analyses revealed that lower relative skeletal muscle mass (ASM/weight) associated significantly with lower values for all three femoral neck composite indices in women and with lower CSI and ISI in men.

CONCLUSIONS

These findings provide the first clinical evidence for the notion that age-related low muscle mass may increase the risk of osteoporotic hip fractures by decreasing femoral neck strength relative to load, especially in older women, and support the highly integrated nature of skeletal muscle and bone.

Higher serum uric acid as a protective factor against incident osteoporotic fractures in Korean men: a longitudinal study using the National Claim Registry

In this large longitudinal study of 16,078 Korean men aged 50 years or older, we observed that baseline elevation of serum uric acid level significantly associated with a lower risk of incident fractures at osteoporosis-related sites during an average follow-up period of 3 years.

INTRODUCTION

Male osteoporosis and related fractures are becoming recognized as important public health concerns. Oxidative stress has detrimental effects on bone metabolism, and serum uric acid (UA) is known to be a strong endogenous antioxidant. In the present study, we performed a large longitudinal study with an average follow-up period of 3 years to clarify the role of UA on the risk of incident osteoporotic fractures (OFs).

METHODS

A total of 16,078 Korean men aged 50 years or older who had undergone comprehensive routine health examinations were enrolled. Incident fractures at osteoporosis-related sites (e.g., hip, spine, distal radius, and proximal humerus) that occurred after the baseline examinations were identified from the nationwide claims database of the Health Insurance Review and Assessment Service of Korea by using selected International Classification of Diseases, 10th revision codes.

RESULTS

In total, 158 (1.0 %) men developed incident OFs. The event rate was 33.1 per 10,000 person-years. Subjects without incident OFs had 6.0 % higher serum UA levels than subjects with OFs (P = 0.001). Multivariable-adjusted Cox proportional hazard analyses adjusted for age, body mass index, glomerular filtration rate, lifestyle factors, medical and drug histories, and the presence of baseline radiological vertebral fractures revealed that the hazard ratio per standard deviation increase of baseline UA levels for the development of incident OFs was 0.829 (95 % CI = 0.695-0.989, P = 0.038).

CONCLUSIONS

These data provide the epidemiological evidence that serum UA may act as a protective factor against the development of incident OFs in Korean men.

Higher serum uric acid is associated with higher bone mass, lower bone turnover, and lower prevalence of vertebral fracture in healthy postmenopausal women

Higher serum uric acid (UA) was associated with higher bone mass, lower bone turnover, and lower prevalence of vertebral fracture in postmenopausal women. Furthermore, UA suppressed osteoclastogenesis and decreased production of reactive oxygen species in osteoclast precursors, indicating UA may have beneficial effects on bone metabolism as an antioxidant.

INTRODUCTION

UA is known to play a physiological role as an antioxidant, and oxidative stress has detrimental effects on bone metabolism. In the present study, we investigated the association of serum UA level with the osteoporosis-related phenotypes and its direct effect on bone-resorbing osteoclasts using in vitro systems.

METHODS

This is a large cross-sectional study, including 7,502 healthy postmenopausal women. Bone mineral density (BMD) and serum UA concentrations were obtained from all subjects. Data on bone turnover markers and lateral thoracolumbar radiographs were available for 1,023 and 6,918 subjects, respectively. An in vitro study investigated osteoclastogenesis and reactive oxygen species (ROS) levels according to UA treatment.

RESULTS

After adjusting for multiple confounders, serum UA levels were positively associated with BMD at all sites (all p < 0.001). Compared with the participants in the highest UA quartile, the odds for osteoporosis were 40 % higher in those in the lowest quartile. The serum UA levels were inversely related to both serum C-terminal telopeptide of type I collagen and osteocalcin levels (p < 0.001 and p = 0.004, respectively). Consistently, subjects with vertebral fracture had lower serum UA levels, compared with those without it (p = 0.009). An in vitro study showed that UA decreased osteoclastogenesis in a dose-dependent manner and reduced the production of ROS in osteoclast precursors.

CONCLUSION

These results provide epidemiological and experimental evidence that serum UA may have a beneficial effect on bone metabolism as an antioxidant in postmenopausal women.

Afamin stimulates osteoclastogenesis and bone resorption via Gi-coupled receptor and Ca2+/calmodulin-dependent protein kinase (CaMK) pathways

BACKGROUND

Afamin was recently identified as a novel osteoclast-derived coupling factor that can stimulate the in vitro and in vivo migration of preosteoblasts.

AIM

In order to understand in more detail the biological roles of afamin in bone metabolism, we investigated its effects on osteoclastic differentiation and bone resorption.

METHODS

Osteoclasts were differentiated from mouse bone marrow cells. Tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells were considered as osteoclasts, and the resorption area was determined by incubating the cells on dentine discs. The intracellular cAMP level was determined using a direct enzyme immunoassay. Signaling pathways were investigated using western blot and RT-PCR. Recombinant afamin was administered exogenously to bone cell cultures.

RESULTS

Afamin stimulated both osteoclastogenesis and in vitro bone resorption. Consistently, the expressions of osteoclast differentiation markers were significantly increased by afamin. Although afamin mainly affected the late-differentiation stages of osteoclastogenesis, the expression levels of receptor activator of nuclear factor-κB ligand (RANKL)-dependent signals were not changed. Afamin markedly decreased the levels of intracellular cAMP with reversal by pretreatment with pertussis toxin (PTX), a specific inhibitor of Gi-coupled receptor signaling. In addition, PTX almost completely blocked afamin-stimulated osteoclastogenesis. Furthermore, pretreatment with KN93 and STO609 - Ca2+/cal - mo dulin-dependent protein kinase (CaMK) and CaMK kinase inhibitors, respectively - significantly prevented decreases in the intracellular cAMP level by afamin while attenuating afamin-stimulated osteoclastogenesis.

CONCLUSION

Afamin enhances osteoclastogenesis by decreasing intracellular cAMP levels via Gi-coupled receptor and CaMK pathways.

The association between higher serum ferritin level and lower bone mineral density is prominent in women ≥45 years of age (KNHANES 2008-2010)

SUMMARY

Data gathered from a nationally representative cohort demonstrate that higher serum ferritin levels are significantly associated with lower bone mass at various skeletal sites and the increased prevalence of osteoporosis and fractures, especially in women ≥45 years of age.

INTRODUCTION

Despite extensive in vitro and in vivo studies showing the detrimental effects of iron on bone metabolism, the clinical studies relating to osteoporosis-related phenotypes have not been evaluated extensively. In the present study, we investigated and compared the association between serum ferritin and bone mineral density (BMD), depending on the stratified age groups in both genders.

METHODS

This is a population-based, cross-sectional study from the Korea National Health and Nutrition Examination Surveys, including 14,017 Koreans (6,817 men and 7,200 women) aged 10-80 years. BMD was measured using dual X-ray absorptiometry, and osteoporosis was diagnosed by the World Health Organization definition.

RESULTS

Initially, we divided the subjects into three age groups, based on the patterns of age-related BMD changes in this national cohort (i.e., ≤24, 25-44, and ≥45 years old). Serum ferritin concentrations were inversely associated with BMD values at all measured sites after adjustment for confounders, only in women ≥45 years of age (P = 0.041 to <0.001). Furthermore, when we divided these women into serum ferritin quartiles, the odds for prevalent osteoporosis and fractures were 1.55-fold (95 % CI = 1.09-2.23) and 1.52-fold (95 % CI = 1.02-2.27) higher, respectively, in subjects in the highest quartile compared with those in the lowest quartile.

CONCLUSIONS

These results provide the first clinical evidence that the associations between serum ferritin level and bone parameters could be the most prominent in women ≥45 years of age.

Association between metabolic syndrome and bone loss at various skeletal sites in postmenopausal women: a 3-year retrospective longitudinal study

Although the presence of metabolic syndrome (MetS) and increasing numbers of MetS components were associated with attenuated bone loss at various skeletal sites in postmenopausal women, this beneficial effect of MetS on bone mass can be mainly explained by higher mechanical loading in the affected subjects.

INTRODUCTION

Previous cross-sectional epidemiological studies reported the inconsistent results regarding the combined effects of MetS on bone mass. In our present report, we performed a large, longitudinal study to evaluate MetS in relation to annualized bone mineral density (BMD) changes in postmenopausal Korean women.

METHODS

The study cohort consisted of 1,218 postmenopausal women who had undergone comprehensive routine health examinations with an average follow-up interval of 3 years. The BMD at the lumbar spine and proximal femur sites was measured with dual-energy X-ray absorptiometry using the same equipment at baseline and at follow-up.

RESULTS

Following adjustment for age, baseline BMD, and lifestyle factors, the women with MetS had 21.7, 17.0, 26.7, and 31.1 % less bone loss at the total femur, femur neck, trochanter, and lumbar spine, respectively, compared with MetS-free women (P = 0.004 to 0.041). Consistently, the rates of bone loss at all skeletal sites were linearly attenuated with increasing numbers of MetS components (P = 0.004 to <0.001). Importantly, when weight and height were added as confounding factors, the differences and trends of annualized BMD changes according to the MetS status disappeared.

CONCLUSION

Our current results indicate that the beneficial effects of MetS on bone mass can be mainly explained by higher mechanical loading in the affected subjects. Consequently, MetS per se may not be a meaningful concept for predicting future bone loss and for explaining associations between osteoporosis and cardiovascular diseases.

Long-term treatment with raloxifene, but not bisphosphonates, reduces circulating sclerostin levels in postmenopausal women

We determined whether suppression of sclerostin levels by estrogen treatment was mediated by anti-resorptive effect. Raloxifene, but not bisphosphonates, suppressed circulating sclerostin concentration, suggesting that sclerostin may mediate the action of estrogen on bone metabolism, independently of their anti-resorptive effects.

INTRODUCTION

Circulating sclerostin concentrations are higher in postmenopausal than in premenopausal women, and estrogen treatment suppresses sclerostin levels in both men and women. We determined whether anti-resorptives may suppress the circulating sclerostin levels.

METHODS

We conducted a retrospective observational study. Eighty postmenopausal women were treated with raloxifene for 19.4 ± 7.7 months (n = 16), bisphosphonates for 19.2 ± 6.7 months (n = 32), or were untreated (n = 32) for 17.1 ± 4.6 months. Plasma sclerostin concentrations were measured before and after treatment.

RESULTS

Plasma sclerostin levels after treatment were significantly lower in the raloxifene than in the control group (55.8 ± 23.4 pmol/l vs. 92.1 ± 50.4 pmol/l, p = 0.046), but were similar between the bisphosphonate and control groups. Relative to baseline, raloxifene treatment markedly reduced plasma sclerostin concentration (-40.7 ± 22.8%, p < 0.001), with respect to both control (-7.5 ± 29.1%) and bisphosphonate (-3.1 ± 35.2%) groups. Changes in bone-specific alkaline phosphatase and osteocalcin levels showed reverse associations with sclerostin concentration changes in the raloxifene (γ = -0.505, p = 0.017) and control (γ = -0.410, p = 0.020) groups.

CONCLUSIONS

Raloxifene, but not bisphosphonates, significantly suppressed circulating sclerostin concentration, suggesting that sclerostin may mediate the action of estrogen on bone metabolism, independently of their anti-resorptive effects.

The association between serum osteocalcin levels and metabolic syndrome in Koreans

The association between serum osteocalcin levels and metabolic syndrome (MS) in Korean individuals was investigated. Serum osteocalcin levels are significantly lower in subjects with MS than in those without the disease, regardless of glucose metabolism.

INTRODUCTION

Osteocalcin was recently shown to affect energy metabolism. In the present study, we investigated the possible association between serum osteocalcin concentrations and MS.

METHODS

A cross-sectional community-based survey was conducted. Serum osteocalcin, type 1 collagen C-telopeptide (CTX) and total alkaline phosphatase (ALP) concentrations were determined in 567 subjects. MS was defined according to NCEP-ATP III criteria.

RESULTS

Serum osteocalcin concentrations were significantly lower in subjects with MS than those without MS in postmenopausal women (18.923 ± 7.685 vs 22.513 ± 7.344 ng/ml, P<0.001) and marginally lower in subjects with MS than those without MS in men (14.550 ± 5.090 vs 16.125 ± 4.749 ng/ml, P=0.086) after adjustment for age and BMI. Further controlling with CTX or ALP did not affect this association in postmenopausal women; however, controlling with osteocalcin abolished the association between CTX and MS. Significant differences in serum osteocalcin levels by MS status were noted in subjects with normal glucose tolerance as well as those with abnormal glucose tolerance (P=0.032 and P<0.001, respectively). Compared with subjects with the highest quartile of osteocalcin, those in the lower quartile groups (Q1-Q3) had significantly increased risks of MS (ORs=5.18, CIs=1.15-23.42) in men. In postmenopausal women, the ORs for MS were significantly higher in the lowest quartile than in the highest quartile (ORs=5.25, CIs=2.42-11.36).

CONCLUSIONS

These findings suggest that osteocalcin is associated with MS, independently of glucose metabolism.

Association of SMAD2 polymorphisms with bone mineral density in postmenopausal Korean women

In a candidate gene association study, we found that SMAD2 promoter alleles and haplotypes were significantly associated with bone mineral density (BMD) at the lumbar spine and various proximal femur sites. Our results suggest that SMAD2 polymorphisms may be one of genetic determinants of BMD in postmenopausal women.

INTRODUCTION

SMAD2, which is the specific intracellular transducer of TGF-ß, is thought to participate in bone metabolism by playing a critical role in the development and function of osteoclasts and osteoblasts. We performed association analyses of the genetic variation in SMAD2 to ascertain the contribution of this gene to BMD and risk of osteoporotic fracture.

METHODS

We selected three SMAD2 promoter single-nucleotide polymorphisms (SNPs) based on heterozygosity and validation status. Postmenopausal Korean women (n = 1,329) were genotyped for these SNPs, and their BMD and risk of fractures were assessed. BMD at the lumbar spine and proximal femur was measured using dual-energy X-ray absorptiometry. P values were corrected for multiple testing by the effective number of independent marker loci (P (cor)).

RESULTS

We found that SMAD2 -35302C>T, -34952A>G, and ht2 were significantly associated with BMD at both the lumbar spine and femur neck (P (cor) = 0.020-0.046), whereas SMAD2 -36201A>G and ht1 affected the femur neck BMD (P (cor) = 0.018-0.031). The genetic effects of these three polymorphisms on BMD at the lumbar spine and femur neck were risk-allele dependent in additive model. The three polymorphisms and two hts were also significantly associated with BMD at other proximal femur sites, such as the total femur, trochanter, and femur shaft (P (cor) = 0.001-0.046). However, none of the polymorphisms or hts was associated with an increased risk of fracture.

CONCLUSIONS

Our results suggest that SMAD2 polymorphisms may be one of genetic determinants of BMD in postmenopausal women.

Fracture, bone mineral density, and the effects of calcitonin receptor gene in postmenopausal Koreans

SUMMARY

In a candidate gene association study, we found that the variations of calcitonin receptor (CALCR) gene were related to the risk of vertebral fracture and increased bone mineral density (BMD).

INTRODUCTION

Calcitonins through calcitonin receptors inhibit osteoclast-mediated bone resorption and modulate calcium ion excretion by the kidney and also prevent vertebral bone loss in early menopause.

METHODS

To identify genetically susceptible factors of osteoporosis, we discovered the variations in CALCR gene, genotyped in Korean postmenopausal women (n = 729), and examined the potential involvement of seven single-nucleotide polymorphism (SNPs) and their haplotypes in linkage disequilibrium block (BL_hts).

RESULTS

The SNPs, +43147G > C (intron 7), +60644C > T (exon13, 3' untranslated region), and their haplotypes, BL2_ht1 and BL2_ht2, showed a significant association with risk of vertebral fracture (p = 0.048-0.004) and BL2_ht1 showed a highly significant protective effect. Moreover, the polymorphism +60644C > T showed a highly significant association with BMD at both lumbar spine and femoral neck. The subjects carrying CC and CT genotypes with the SNP, +60644C > T, had higher BMD values at the lumbar spine (p = 0.01-0.001) and femoral neck (p = 0.025-0.009).

CONCLUSION

These results indicate that the CALCR gene may regulate bone metabolism, and +60644C > T in the CALCR gene may genetically modulate bone phenotype.

Association of TWIST1 gene polymorphisms with bone mineral density in postmenopausal women

A novel polymorphism (+1871A>G) in the 3' flanking region and haplotypes were significantly associated with reduced osteoporosis risk and enhanced bone mineral density (BMD). These results suggest that TWIST1 may be a useful genetic marker for osteoporosis. Our results provide preliminary evidence supporting an association of TWIST1 with osteoporosis in postmenopausal women.

INTRODUCTION

TWIST1, a basic helix-loop-helix (bHLH) transcription factor, has been implicated in cell lineage determination and differentiation.

METHODS

To address the genetic variations in the TWIST1 gene associated with osteoporosis, we investigated the potential involvement of three TWIST1 single-nucleotide polymorphisms (SNPs) in osteoporosis in 729 postmenopausal women. BMD was measured using dual-energy X-ray absorptiometry.

RESULTS

A novel polymorphism in the 3' flanking region (+1871A>G) was significantly associated with osteoporosis risk (p = 0.007-0.008) and also in multiple comparison (p = 0.02). Consistent with these results, haplotype analysis showed that Block1_ht2 had protective effects in the dominant and additive model (p = 0.006-0.007). Specifically, the +1871A>G polymorphism was overdominantly associated with higher BMD values of the femoral neck (p = 0.039).

CONCLUSION

These results suggest that TWIST1 may be a useful genetic marker for osteoporosis and may have a role on bone metabolism in humans. Our results provide preliminary evidence supporting an association of TWIST1 with osteoporosis in postmenopausal women.

Identification of novel RANK polymorphisms and their putative association with low BMD among postmenopausal women

INTRODUCTION

Bone mineral density (BMD) is the major factor for determining bone strength, which is closely correlated to osteoporotic fracture risk and is largely determined by multiple genetic factors. The RANK (TNFRSF11A), receptor for RANKL, is a member of the tumor necrosis factor receptor (TNFR) superfamily and plays a central role in osteoclast development.

METHODS

In order to investigate the effects of RANK polymorphism on BMD and osteoporosis, we directly sequenced the RANK gene in 24 Korean individuals and identified 25 sequence variants. Eleven of these polymorphisms were selected and genotyped in a larger-scale study of postmenopausal women (n = 560). Areal BMD (g/cm(2)) of the anterior-posterior lumbar spine and the nondominant proximal femur were measured using dual-energy X-ray absorptiometry.

RESULTS

We found that two intronic polymorphisms in the RANK gene [RANK + 34863G > A (rs12458117) and RANK + 35928insdelC (new polymorphism found in this study) in intron 6] were significantly associated with the BMD of the lumbar spine, i.e., rare alleles were significantly associated with low BMD of the lumbar spine among Korean postmenopausal women (p = 0.04 and 0.02, respectively). These polymorphisms were also associated with low BMD of proximal femur sites, including Ward's triangle, trochanter, and total femur. Our results suggest that +34863G > A and +35928insdelC polymorphisms in RANK are possible genetic factors for low BMD in postmenopausal women.

Association of PLXNA2 polymorphisms with vertebral fracture risk and bone mineral density in postmenopausal Korean population

INTRODUCTION

Plexin A2 (PLXNA2) is a receptor that recognizes secreted or membrane-bound semaphorin 3A, which is implicated in neural regulation of bone metabolism.

MATERIALS AND METHODS

In the present study, we identified 48 genetic polymorphisms in PLXNA2 by resequencing, and 10 single nucleotide polymorphisms (SNPs) were selected for further investigation into their potential involvement in osteoporosis in a postmenopausal population (n=560).

RESULTS

Two SNPs, +14G>A (Gln5Arg) and +183429C>T (Tyr1621Tyr), and Block1-ht2 were associated with risk of vertebral fracture (p=0.01-0.05), and three SNPs, +799G>A (Ala267Thr), +135391G>A, and +190531G>C, were associated with bone mineral density at various femur sites (p=0.003-0.03). Particularly, the minor allele of +14G>A was associated with a protective effect on vertebral fracture and higher lumbar bone mineral density, suggesting that +14G>A may be a useful marker for osteoporosis and its related fracture.

CONCLUSION

These results provide, for the first time, evidence supporting the association of PLXNA2 with osteoporosis in postmenopausal women.

Increased urinary albumin excretion in Cushing's syndrome: remission after correction of hypercortisolaemia

OBJECTIVES

Increased urinary albumin excretion (UAE) in diabetic and nondiabetic subjects is frequently associated with insulin resistance syndrome and central obesity. Cushing's syndrome is also characterized by central obesity and insulin resistance. This study was undertaken to see whether increased UAE is found in Cushing's syndrome.

DESIGN

Cross-sectional study.

PATIENTS

Thirteen consecutive patients with Cushing's syndrome.

MEASUREMENTS

Patients collected three overnight urine samples for the measurement of UAE by radioimmunoassay. UAE was also measured in 479 nondiabetic subjects who comprised the control population for this study. In the patients who had initial microalbuminuria, UAE was remeasured 2 months after successful removal of pituitary or adrenal tumours. Kidney biopsy was performed in three patients during adrenalectomy.

RESULTS

Eleven out of 13 patients (84.6%) had increased UAE (> 9.6 micrograms/min), and eight patients (61.5%) had microalbuminuria or overt proteinuria (> 20 micrograms/min). Kidney biopsy revealed apparently normal glomerular structures without evidence of diabetic nephropathy. After correction of hypercortisolaemia, UAE declined profoundly in all of the patients.

CONCLUSIONS

More than 80% of patients with Cushing's syndrome had increased UAE. This was almost completely reversed after successful treatment of hypercortisolaemia. These results indicate that endogenous hypercortisolaemia increases UAE by a mechanism that is presently unknown.

Prevalences of Gs alpha, ras, p53 mutations and ret/PTC rearrangement in differentiated thyroid tumours in a Korean population

OBJECTIVE

In thyroid tumours, ras, Gs alpha, p53 mutations and ret/PTC rearrangement have been reported with variable prevalences in different geographical regions. We studied the prevalence of these mutations and rearrangement in thyroid tumours in a Korean population. As MDM2 and Bcl-1 protein expressions have been suggested to be associated with p53 protein, we also studied possible relationships among them.

PATIENTS AND DESIGN

Eleven cases of adenomatous goitre, eight cases of follicular adenoma, five cases of follicular carcinoma and 37 cases of papillary carcinoma were included in this study. To find mutations and rearrangement, RT-PCR, SSCP and/or direct sequencing, after subcloning if necessary, were used, and immunohistochemical stainings were performed for p53, MDM2 and Bcl-2 proteins in cases of papillary carcinoma.

RESULTS

We could not find any rearrangement for ret/PTC-1, -2, -3 and mutation of Gs alpha. For the ras oncogene, K and H-ras mutations were not found, but N-ras mutations, point mutation of CAA to CGA in codon 61, were detected in one follicular adenoma (12.5%, 1/8) and one follicular carcinoma (33%, 1/3). p53 mutations were detected in only one case of papillary carcinoma (3%, 1/31: exon 8, codon 266 GGA-->GAA). In 30 cases of papillary carcinoma without p53 mutation, the prevalences of positive immunohistochemical staining were 13.3% for p53 protein, 53.3% for MDM2 protein and 56.7% for Bcl-2 protein. While over-expression of p53 protein was not significantly related to that of MDM2 and Bcl-2 proteins, over-expression of MDM2 and Bcl-2 in papillary carcinoma were associated.

CONCLUSION

ret/PTC rearrangement, Gs alpha, ras and p53 mutations are relatively rare in differentiated thyroid neoplasms from a Korean population, which may reflect genetic and environmental differences from patients in countries with high prevalences. P53 protein over-expression was noted in 13.3% of papillary carcinoma cases without p53 mutation and was not significantly related to MDM2 and Bcl-2 expression.

Primary ovarian failure caused by a solvent containing 2-bromopropane

Sixteen Korean female laborers who had been exposed to a cleaning solvent composed mainly of 2-bromopropane developed primary ovarian failure. Histologic findings from these patients' ovaries were similar to those observed in ovarian failure caused by radiation or chemotherapy, i.e., reduced number and developmental arrest of primary follicles, interstitial fibrosis and hyalinization of blood vessels. We followed their clinical course for 2 years and found that two patients recovered normal ovarian function spontaneously: one became pregnant and delivered a normal full-term baby, and the other resumed regular menstrual periods with normal hormonal values. Our observations support the idea that the increasing prevalence of ovarian failure in recent years might be due to an increase in presently unidentified environmental toxic agents.