Sex steroid metabolism in the regulation of bone health in men

Contribution of thick ascending limb and distal convoluted tubule to glucose-induced hypercalciuria in healthy controls

Carbohydrates increase kidney stone risk and increase urine calcium and magnesium. We hypothesize that the effects of glucose as an allosteric modulator of calcium-sensing receptors may mediate this effect. Six healthy subjects were on a low-sodium diet before consuming 100 g of glucose beverage. Timed fasting (3) and postglucose (6) urine and blood samples were collected every 30 min. Urine composition and serum markers were measured and microvesicular abundance of tubular transport proteins (NHE3, NKCC2, NCC, and TRPV5) were quantified. Postglucose, serum glucose, and insulin rose rapidly with a parallel increase in calcium and magnesium excretion and no change in fractional excretion of sodium. Both serum parathyroid hormone (PTH) and urine TRPV5 fell in the postglucose periods. The rise in the calcium and magnesium excretion likely occurred primarily in the thick ascending limb where they are both under control of the calcium-sensing receptor. The fall in PTH and TRPV5 support the role of glucose as an allosteric modulator of calcium-sensing receptor.NEW & NOTEWORTHY Sugar increases urine calcium and magnesium as well as kidney stone and bone disease risk. Our study provided new insights into the underlying mechanism as we gave healthy subjects an oral glucose load and used newer tools such as fractional excretion of lithium, serum parathyroid hormone, and microvesicular abundance of tubular transport proteins to characterize the mechanism and identify the thick ascending limb with possible calcium-sensing receptor mediation as a likely contributor to this mechanism.

Testosterone and aging male, a perspective from a developing country

PURPOSE

Hypogonadism is associated with a wide range of physical and psychological symptoms that can affect the overall health of men. However, in a developing country, there are several imposing challenges in the diagnosis and treatment of hypogonadism, including a lack of awareness and understanding of the condition among healthcare providers and patients, limited resources and the high cost of treatment. This review aimed to examine the potential benefits and risks of testosterone replacement therapy (TRT) and provides a perspective of a developing country on the topic.

MATERIALS AND METHODS

A comprehensive literature review was conducted to gather relevant information on the impact of testosterone deficiency on ageing males and the effectiveness of TRT for treating hypogonadism. Published peer-reviewed articles were analyzed to evaluate the benefits and risks of TRT. Additionally, the unique challenges faced in the diagnosis and treatment of hypogonadism in a developing country were considered.

RESULTS

Testosterone replacement therapy has been shown to be an effective treatment for hypogonadism, particularly in symptomatic men with low testosterone levels. It offers potential benefits such as improvements in symptoms and overall quality of life. However, there are associated risks and side effects that need to be considered. In a developing country, challenges such as limited awareness and understanding of hypogonadism, resource constraints, and high treatment costs pose additional barriers to accessing TRT and comprehensive care.

CONCLUSION

In conclusion, TRT holds promise as a treatment for hypogonadism, but its implementation and accessibility face significant challenges in a developing country. Addressing these challenges, including raising awareness, allocating resources, and finding cost-effective solutions, is crucial for ensuring that men with hypogonadism in such settings receive appropriate diagnosis and treatment. Further research and efforts are needed to improve the management of hypogonadism in developing countries and optimize the potential benefits of TRT for affected individuals.

Is gender a factor affecting long-term heterotopic ossification incidence after single-level cervical disc arthroplasty?

BACKGROUND

Cervical disc diseases have been treated by means of cervical disc arthroplasty (CDA). Nevertheless, some patients will experience a mobility failure in their cervical prostheses over time because of heterotopic ossification (HO). Aim of this study is to investigate the role of gender in long-term outcomes after CDA.

MATERIALS AND METHODS

A retrospective, single-center study including patients who underwent single-level CDA with a Bryan prosthesis was performed, including a narrative review about gender differences in both structural and biomechanical features of the cervical spine.

RESULTS

Study patients (14M, 30F) had an average follow-up period of 9,8 ± 3,2 years. Significant differences emerged between genders for specific items in Neck Disability Index (NDI) preoperative evaluation, with females reporting worse pain scores (p=0.05). After stratification by age we report a higher preoperative overall NDI score for female patients under 36 years of age (p=0.03). In an intergender, BMI-specific comparison we also found a significant difference in NDI preoperative score with normal-weight male patients faring worse than overweight ones (p= 0.05). At a radiological level, we found a tendency towards a higher HO incidence in male patients (62% males, 17% females, p=0.06). Women's cervical spine has peculiar features including bone structure, muscular action, soft-tissue response, genetic and epigenetic response to osteoarthritis.

CONCLUSION

The incidence of mobility failure in our series of single-level CDA was lower in females. Several gender specific factors both in static and dynamic features may play a significant role in spinal pathology and CDA long-term radiological outcome.

Impact of Low Energy Availability on Skeletal Health in Physically Active Adults

For decades researchers reported that pre-menopausal women who engage in extensive endurance exercise and have menstrual dysfunction can develop low bone mineral density (BMD) or osteoporosis. More recently, low energy availability has been recognized as the initiating factor for low BMD in these women. Furthermore, the relationship between low energy availability and poor skeletal health is not exclusive to women engaging in endurance exercise. Rather, both males and females commonly experience endocrine dysfunction resulting from low energy availability and high exercise levels that degrades skeletal health. Consequences to skeletal health can range from short-term changes in bone metabolism and increased risk of bone stress injuries to long-term consequences of low BMD, such as osteoporosis and related fragility fractures. The degree to which low energy availability degrades skeletal health may be dependent on the length and extent of the energy deficit. However, the complex relationships between under-fueling, short- and long-term skeletal consequences and the factors that mediate these relationships are not well described. In this review, we discuss the consequences of low energy availability on sex hormones and skeletal health in two highly-active populations-athletes and military trainees-and provide a summary of existing knowledge gaps for future study.

Supraphysiological testosterone supplementation improves granulation tissue maturation through angiogenesis in the early phase of a cutaneous wound healing model in rats

OBJECTIVE

The aim of this study was to evaluate the effects of both testosterone depletion and supraphysiological testosterone supplementation in the early phase of an animal cutaneous wound healing model in comparison with the physiological hormonal condition.

MATERIAL AND METHODS

Forty rats were distributed into the following four groups: Control, Orchiectomy (OCX), Durateston (Dura) and OCX+Dura. On day 1, the testicles were removed (OCX group) and the rats (Dura group) received a supraphysiological dose (250 mg/kg) of exogenous testosterone weekly. After 15 days a full-thickness excisional skin wound was created in all animals, which was healed by the second intention for 7 days. On day 22, the rats were euthanatized and the wounds were harvested for histopathological evaluation, immunohistochemistry analyses and multiplex immunoassay. One-way ANOVA and post-hoc Tukey tests were performed.

RESULTS

It was found that the supraphysiological testosterone level increased extracellular matrix deposition, promoted higher blood vessel formation and reduced wound contraction (p < 0.05). Additionally, it also stimulated PCNA-positive fibroblasts and KGF-positive cells (p < 0.05), while orchiectomy reduced the expression of IL-6 and TNF-α and increased VEGF and PDGF (p < 0.05) .

CONCLUSION

In conclusion, the results provide evidence that supraphysiological testosterone supplementation plays a positive role in the early phase of cutaneous wound healing, thus improving granulation tissue maturation through the enhancement of angiogenesis.

Management of Osteoporosis in Men: A Narrative Review

Male osteoporosis is a still largely underdiagnosed pathological condition. As a consequence, bone fragility in men remains undertreated mainly due to the low screening frequency and to controversies in the bone mineral density (BMD) testing standards. Up to the 40% of overall osteoporotic fractures affect men, in spite of the fact that women have a significant higher prevalence of osteoporosis. In addition, in males, hip fractures are associated with increased morbidity and mortality as compared to women. Importantly, male fractures occur about 10 years later in life than women, and, therefore, due to the advanced age, men may have more comorbidities and, consequently, their mortality is about twice the rate in women. Gender differences, which begin during puberty, lead to wider bones in males as compared with females. In men, follicle-stimulating hormones, testosterone, estrogens, and sex hormone-binding levels, together with genetic factors, interact in determining the peak of bone mass, BMD maintenance, and lifetime decrease. As compared with women, men are more frequently affected by secondary osteoporosis. Therefore, in all osteoporotic men, a complete clinical history should be collected and a careful physical examination should be done, in order to find clues of a possible underlying diseases and, ultimately, to guide laboratory testing. Currently, the pharmacological therapy of male osteoporosis includes aminobisphosphonates, denosumab, and teriparatide. Hypogonadal patients may be treated with testosterone replacement therapy. Given that the fractures related to mortality are higher in men than in women, treating male subjects with osteoporosis is of the utmost importance in clinical practice, as it may impact on mortality even more than in women.

Is There a Relationship Between Bony Fusion After Anterior Cervical Discectomy and Fusion and Heterotopic Ossification After Cervical Disc Arthroplasty in Hybrid Surgery?

STUDY DESIGN

Retrospective analysis.

OBJECTIVE

The aim of this study was to investigate the relationship between bony fusion after anterior cervical discectomy and fusion (ACDF) and heterotopic ossification (HO) after cervical disc arthroplasty (CDA) in hybrid surgery (HS).

SUMMARY OF BACKGROUND DATA

The mechanism of postoperative bone formation still remains unknown. It is considered a risk factor in CDA but is essential for a solid union in ACDF. With HS, we could directly study the mechanism and relationship of different forms of postoperative bone formation.

METHODS

Clinical data of 91 patients who had undergone consecutive two-level HS between January 2011 and January 2018 and with a minimum of 2-year follow-up was analyzed. HO was assessed based on McAfee's classifications, whereas fusion success was evaluated according the Food and Drug Administration approved criteria. Clinical outcomes and radiographic parameters were collected and used for the relevant comparisons.

RESULTS

HO was identified in 48.4% of patients (44/91). The fusion rates of patients in the HO group and the non-HO group at 3, 6, and 12 months postoperatively, and the final follow-up were 81.8% and 19.1%, 95.4% and 74.5%, 95.4% and 85.1%, and 97.7% and 93.6%, respectively. The fusion rates were significantly higher at 3 and 6 months after operation in the HO group than in the non-HO group (P < 0.05). Patients in both groups had significant improvements across all clinical outcomes at final follow-up.

CONCLUSION

There was a significant relationship between bony fusion and occurrence of HO after HS, suggesting that both bony fusion and HO are reflections of individual osteogenic capacity. However, a reliable predictor of postoperative bone formation is needed in the future to guarantee a solid bony fusion after ACDF and to further take full advantage of the motion-preserving from CDA.

LEVEL OF EVIDENCE

3.

Mandibular-related bone metabolism in orchiectomized rats treated with sex hormones

OBJECTIVE

This study aimed to compare the impact of testosterone and estrogen replacement therapy on mandibular bone density and bone-related markers.

DESIGN

Forty male adult rats were randomly allocated to 4 experimental groups (n = 10/group): Sham (Control); Orchiectomy; Orchiectomy plus testosterone replacement; and orchiectomy plus estradiol replacement. Twenty-four days after orchiectomy, the hemi-mandibles were collected and processed for analysis of microhardness in cortical and trabecular bone, radiographic bone density and histomorphometric evaluation. Serum was collected for the analysis of calcium, phosphorus, alkaline phosphatase and magnesium.

RESULTS

The orchiectomy group had the lowest mandibular bone density (p < 0.01) and also their serum levels of alkaline phosphatase were higher than all other experimental groups (p < 0.001). Estradiol replacement significantly reduced microhardness when compared to orchiectomy in cortical bone (p < 0.05). Both testosterone and estrogen replacement reverted orchiectomy impact on this parameter (p < 0.01); and decreased alkaline phosphatase to levels comparable to the Sham-Control group. The effect of estrogen was more pronounced than testosterone, and a statistically significant difference was observed between Sham-Control and testosterone replacement (p < 0.05) but not between Sham-Control and estradiol replacement groups.

CONCLUSION

Our findings demonstrated that both estradiol and testosterone replacement therapies play a role in mandibular bone metabolism, but suggest different pathways.

Late-onset Hypogonadism: Bone health

BACKGROUND

Bone health is underdiagnosed and undermanaged in men. Bone loss occurs in men with hypogonadism and in aging men. Thus, patients with a diagnosis of late-onset hypogonadism (LOH) are at risk of osteoporosis and osteoporotic fractures.

OBJECTIVES

To provide an update on research data and clinical implications regarding bone health in men with LOH by reviewing literature articles on this issue.

MATERIALS AND METHODS

A thorough search of listed publications in PubMed on bone health in older men with hypogonadism was performed, and other articles derived from these publications were further identified.

RESULTS

Late-onset Hypogonadism may be associated with reduced bone mineral density (BMD). In a pathophysiological perspective, the detrimental effects of testosterone (T) deficiency on BMD are partly ascribed to relative estrogen deficiency and both serum T and serum estradiol (E2) need to be above 200 ng/dL and 20 pg/mL to prevent bone loss. The effects of exogenous T on BMD are controversial, but most of the studies confirm that testosterone replacement therapy (TRT) increases BMD and prevents further bone loss in men with hypogonadism. No data are available on TRT and the prevention of fractures.

DISCUSSION AND CONCLUSION

In men with documented LOH, a specific clinical workup should be addressed to the diagnosis of osteoporosis in order to program subsequent follow-up and consider specific bone active therapy. TRT should be started according to guidelines of male hypogonadism while keeping in mind that it may also have positive effects also on bone health in men with LOH.

Analysis of correlation between estradiol and fracture of femur neck

Osteoporosis is a major public health challenge all over the world. Estrogen hormone was cited amongst other hormones to be an efficient hormone for the production and maintenance of bone density. This study was designed with the purpose of evaluating and analyzing the estradiol effect on fractures of femur neck in the Iranian society. This study evaluated men over 50 years of age suffering with mild trauma (falling off the same level height or lower) and with a fracture on their femur neck. Also, their serum level of estradiol was measured with an ELISA method. Using this procedure, the patients were assigned into groups with either normal estradiol serum level (10pg/ml and higher) or with lower than normal level (lower than 10 pg/ml). A control group including 50-year-old and older men without hip fracture, or its history, was chosen to access their estradiol serum level. Data collected from these two groups were statistically compared. A total of 120 patients were evaluated (60 in the control and 60 in the test group). The mean age of patients in the control and test groups were 67.9±10.22 and 69.5±8.84 years, respectively (p=0.376). Smoker patients’ percentages in the control and test groups were 35% and 31.7%, respectively (p=0.699). On the basis of the serum estradiol level, patients’ percentages with low estradiol level in control and test groups were 10% and 16.7%, respectively (p=0.283). The only significant factor in predicting serum estradiol level was smoking. In conclusion, in this study it was observed that fractures of the femoral neck following a mild trauma were not correlated to low level of serum estradiol.

Serum total estradiol, but not testosterone is associated with reduced bone mineral density (BMD) in HIV-infected men: a cross-sectional, observational study

SUMMARY

By investigating the relationship between serum testosterone, estradiol, and bone mineral density (BMD) in a large cohort of HIV-infected men, estradiol was associated with BMD, relative estrogen deficiency being involved in bone loss in men with hypogonadism, in addition to all HIV-related factors. Increased aromatization in adipose tissue does not counteract HIV-related bone loss.

INTRODUCTION

The purpose of this study is to evaluate the relationship between serum testosterone, estradiol, and BMD in a large cohort of HIV-infected men.

METHODS

We investigated biochemical, hormonal parameters, and BMD in 1204 HIV-infected men (age 45.64 ± 7.33 years) participating in a cross-sectional, observational study. Among other parameters, the main outcome measures were serum total testosterone and estradiol, gonadotropins, 25-hydroxyvitamin D [25(OH)D], parathormone (PTH), calcium, phosphorous, femoral, and lumbar BMD.

RESULTS

In men with HIV, the prevalence of osteoporosis and osteopenia is 15.1 and 63.2% with 25(OH)D insufficiency being very common (60.1%). After age adjustment, BMD is positively associated with estradiol, but not testosterone, at linear (p < 0.001) and stepwise (p < 0.05) multiple regression. Lumbar BMD significantly increases across the estradiol quartiles but not among testosterone quartiles. Femoral and lumbar BMD are significantly higher in men with estradiol ≥ 27 pg/mL than in those with estradiol <27 pg/mL. Apart from estradiol, only age, calcium, and BMI predict BMD at stepwise linear multiple regression, but the strength of this association is weak.

CONCLUSIONS

Estradiol, but not testosterone, is associated with BMD in HIV-infected men and exerts a protective role on bone especially when it is above 27 pg/mL. Relative estrogen deficiency is a potential mechanism involved in bone loss in hypogonadal HIV-infected men, in addition to all HIV-related factors. Increased aromatization in adipose tissue does not counteract HIV-related bone loss. Finally, reduced BMD in young-to-middle-aged HIV-infected men might be considered a peculiar hallmark of HIV infection due to its relevant prevalence, representing one of the several pieces composing the complicated puzzle of premature aging related to HIV infection.

Androgen receptors and experimental bone loss - an in vivo and in vitro study

Testosterone is a sex hormone that exhibits many functions beyond reproduction; one such function is the regulation of bone metabolism. The role played by androgen receptors during testosterone-mediated biological processes associated with bone metabolism is largely unknown. This study aims to use a periodontal disease model in vivo in order to assess the involvement of androgen receptors on microbial-induced inflammation and alveolar bone resorption in experimental bone loss. The impact of hormone deprivation was tested through both orchiectomy and chemical blockage of androgen receptor using flutamide (FLU). Additionally, the direct effect of exogenous testosterone, and the role of the androgen receptor, on osteoclastogenesis were investigated. Thirty male adult rats (n=10/group) were subjected to: 1-orchiectomy (OCX); 2-OCX sham surgery; or 3-OCX sham surgery plus FLU, four weeks before the induction of experimental bone loss. Ten OCX sham-operated rats were not subjected to experimental bone loss and served as healthy controls. The rats were euthanized two weeks later, so as to assess bone resorption and the production of inflammatory cytokines in the gingival tissue and serum. In order to study the in vitro impact of testosterone, osteoclasts were differentiated from RAW264.7 cells and testosterone was added at increasing concentrations. Both OCX and FLU increased bone resorption, but OCX alone was observed to increase osteoclast count. IL-1β production was increased only in the gingival tissue of OCX animals, whereas FLU-treated animals presented a decreased expression of IL-6. Testosterone reduced the osteoclast formation in a dose-dependent manner, and significantly impacted the production of TNF-α; FLU partially reversed these actions. When taken together, our results indicate that testosterone modulates experimental bone loss, and that this action is mediated, at least in part, via the androgen receptor.

Risk of Fractures and Falls during and after 5-α Reductase Inhibitor Use: A Nationwide Cohort Study

Background

Lower urinary tract symptoms are common among older men and 5-α reductase inhibitors (5-ARI) are a group of drugs recommended in treating these symptoms. The effect on prostate volume is mediated by a reduction in dihydrotestosterone; however, this reduction is counterbalanced by a 25% rise in serum testosterone levels. Therefore, 5-ARI use might have systemic effects and differentially affect bone mineral density, muscular mass and strength, as well as falls, all of which are major determinants of fractures in older men.

Methods

We conducted a nationwide cohort study of all Swedish men who used 5-ARI by comparing their risk of hip fracture, any type of fracture and of falls with matched control men randomly selected from the population and unexposed to 5-ARI.

Results

During 1 417 673 person-years of follow-up, 10 418 men had a hip fracture, 19 570 any type of fracture and 46 755 a fall requiring hospital care. Compared with unexposed men, current users of 5-ARI had an adjusted hazard ratio (HR) of 0.96 (95% CI 0.91–1.02) for hip fracture, an HR of 0.94 (95% CI 0.90–0.98) for all fracture and an HR of 0.99 (95% CI 0.96–1.02) for falls. Former users had an increased risk of hip fractures (HR 1.10, 95% CI 1.01–1.19).

Conclusion

5-ARI is safe from a bone health perspective with an unaltered risk of fractures and falls during periods of use. After discontinuation of 5-ARI, there is a modest increase in the rate of fractures and falls.

Effect of a single injection of testosterone enanthate on 17β estradiol and bone turnover markers in hypogonadal male patients

PURPOSE

Several clinical studies testify the critical role played by estrogens in male bone metabolism. The aim of our study is to assess the effect of a single injection of testosterone enanthate in a group of hypogonadal men on 17β estradiol serum levels and some bone metabolic parameters.

METHOD

Twenty-one hypogonadal males were given one testosterone enanthate injection (250 mg). Blood samples were drawn before the injection and after 1, 2 and 3 weeks. The following variables were measured: Total testosterone (TT), 17β estradiol (17β E2), Sex hormone binding globulin, total alkaline phosphatase, osteocalcin, and C-telopeptide of type I collagen (CTx).

RESULTS

After testosterone injection, both TT and 17β E2 increased, peaking 1 week after the injection. Individual observation of the response of 17β E2 to testosterone showed that a subgroup (n = 9) failed to respond with any increase in 17β E2 at any of the weekly tests (group E2-), while the remainder (n = 12) showed a significant increase in 17β E2, which reached a mean value three times higher than at baseline (group E2+). The E2- patients reached a TT peak lower than that observed in the E+ group. CTx serum levels declined progressively in the E2+ group, reaching the significance (p = 0.03) at the end of the study, while it did not change in E- group.

CONCLUSION

This study suggests that a single injection of testosterone might have different effects on the production of endogenous estrogens, and a significant reduction of bone resorption parameters takes place only in the patients who show a significant increase of 17ß estradiol in response to testosterone administration.

The endocrine role of estrogens on human male skeleton

Before the characterization of human and animal models of estrogen deficiency, estrogen action was confined in the context of the female bone. These interesting models uncovered a wide spectrum of unexpected estrogen actions on bone in males, allowing the formulation of an estrogen-centric theory useful to explain how sex steroids act on bone in men. Most of the principal physiological events that take place in the developing and mature male bone are now considered to be under the control of estrogen. Estrogen determines the acceleration of bone elongation at puberty, epiphyseal closure, harmonic skeletal proportions, the achievement of peak bone mass, and the maintenance of bone mass. Furthermore, it seems to crosstalk with androgen even in the determination of bone size, a more androgen-dependent phenomenon. At puberty, epiphyseal closure and growth arrest occur when a critical number of estrogens is reached. The same mechanism based on a critical threshold of serum estradiol seems to operate in men during adulthood for bone mass maintenance via the modulation of bone formation and resorption in men. This threshold should be better identified in-between the ranges of 15 and 25 pg/mL. Future basic and clinical research will optimize strategies for the management of bone diseases related to estrogen deficiency in men.

Impaired hypertrophy in myoblasts is improved with testosterone administration

We investigated the ability of testosterone (T) to restore differentiation in multiple population doubled (PD) murine myoblasts, previously shown to have a reduced differentiation in monolayer and bioengineered skeletal muscle cultures vs. their parental controls (CON) (Sharples et al., 2011, 2012 [7,26]). Cells were exposed to low serum conditions in the presence or absence of T (100nM)±PI3K inhibitor (LY294002) for 72h and 7 days (early and late muscle differentiation respectively). Morphological analyses were performed to determine myotube number, diameter (μm) and myonuclear accretion as indices of differentiation and myotube hypertrophy. Changes in gene expression for myogenin, mTOR and myostatin were also performed. Myotube diameter in CON and PD cells increased from 17.32±2.56μm to 21.02±1.89μm and 14.58±2.66μm to 18.29±3.08μm (P≤0.05) respectively after 72h of T exposure. The increase was comparable in both PD (+25%) and CON cells (+21%) suggesting a similar intrinsic ability to respond to exogenous T administration. T treatment also significantly increased myonuclear accretion (% of myotubes expressing 5+ nuclei) in both cell types after 7 days exposure (P≤0.05). Addition of PI3K inhibitor (LY294002) in the presence of T attenuated these effects in myotube morphology (in both cell types) suggesting a role for the PI3K pathway in T stimulated hypertrophy. Finally, PD myoblasts showed reduced responsiveness to T stimulated mRNA expression of mTOR vs. CON cells and T also reduced myostatin expression in PD myoblasts only. The present study demonstrates testosterone administration improves hypertrophy in myoblasts that basally display impaired differentiation and hypertrophic capacity vs. their parental controls, the action of testosterone in this model was mediated by PI3K/Akt pathway.

The predisposing factors for the heterotopic ossification after cervical artificial disc replacement

BACKGROUND CONTEXT

Heterotopic ossification (HO) is defined as a formation of bone outside the skeletal system. The reported HO occurrence rate in cervical artificial disc replacement (ADR) is unexpectedly high and is known to vary. However, the predisposing factors for HO in cervical ADR have not yet been elucidated.

PURPOSE

Investigation of the predisposing factors of HO in cervical arthroplasty and the relationship between degeneration of the cervical spine and HO occurrence.

STUDY DESIGN

Retrospective study to discover predisposing factors of HO in cervical arthroplasty.

PATIENT SAMPLE

A total of 170 patients who underwent cervical ADR were enrolled including full follow-up clinical and radiologic data.

OUTCOME MEASURES

Radiologic outcomes were assessed by identification of HOs according to McAfee's classifications.

METHODS

This study enrolled a total of 170 patients who underwent cervical ADR. Pre-existing degenerative change included anterior or posterior osteophytes, ossification of the anterior longitudinal ligament, posterior longitudinal ligament, or ligamentum nuchae. The relationships between basic patient data, pre-existing degenerative change, and HO were investigated using linear logistic regression analysis.

RESULTS

Among all 170 patients, HO was found in 69 patients (40.6%). Among the postulated predisposing factors, only male gender and artificial disc device type were shown to be statistically significant. Unexpectedly, preoperative degenerative changes in the cervical spine exerted no significant influence on the occurrence of HOs. The odds ratio of male gender compared with female gender was 2.117. With regard to device type, the odds ratios of Mobi-C (LDR medical, Troyes, France) and ProDisc-C (Synthes, Inc., West Chester, PA, USA) were 5.262 and 7.449, respectively, compared with the Bryan disc.

CONCLUSIONS

Definite differences in occurrence rate according to the gender of patients and the prosthesis type were identified in this study. Moreover, factors indefinably expected to influence HO in the past were not shown to be risk factors thereof, the results of which may be meaningful to future studies.

Effects of low-dose testosterone undecanoate treatment on bone mineral density and bone turnover markers in elderly male osteoporosis with low serum testosterone

This prospective 2-year, single-center, randomized, placebo-controlled, open-label clinical trial was performed to evaluate the efficacy of low-dose testosterone undecanoate (TU) treatment on bone mineral density (BMD) and biochemical markers of bone turnover in elderly male osteoporosis with low serum testosterone. A total of 186 elderly male osteoporosis patients with low serum testosterone were randomized into three groups: low-dose TU (20 mg, per day), standard-dose TU (40 mg, per day), and placebo group with a 24-month followup. Since the 6th month in standard-dose TU group or since the 12th month followup in low-dose TU group and throughout the study, lumbar spine and femoral neck BMD and serum levels of free testosterone, estradiol, and bone alkaline phosphatase significantly increased. There were no significant differences between groups of low-dose TU and standard dose TU in the percentage of changes of these data since the 18th month followup and throughout the study. No side effects on prostate glands including prostate specific antigen were found. In conclusion, low-dose TU (20 mg, per day) may be a cost effective and safe protocol for treating elderly male osteoporosis with low serum testosterone.

Estradiol levels predict bone mineral density in male collegiate athletes: a pilot study

OBJECTIVE

  Strenuous training commonly results in amenorrhoea, which contributes to bone loss in some female collegiate athletes. However, the impact of athletic training on endocrine function and bone mineral density (BMD) in male collegiate athletes is less well understood. The objective of the study was to investigate the specific endocrine determinants of BMD in male collegiate runners and wrestlers, including the potential impact of gonadal steroid levels.

DESIGN

  Cross-sectional study.

PATIENTS

  Twenty-six division I collegiate male athletes (wrestlers, runners and golfers).

MEASUREMENTS

  Main outcome measures included (i) BMD endpoints measured by dual energy x-ray absorptiometry (DXA); (ii) endocrine end-points: total and free oestradiol, total and free testosterone; (iii) body composition end-points: lean and fat mass, measured by DXA; and (iv) exercise end-points: maximal oxygen uptake (VO(2) max), number of miles run weekly and grip strength.

RESULTS

  Free and total oestradiol levels were important positive determinants of BMD. In contrast, total and free testosterone levels were not significant predictors of BMD at any skeletal site (except for free testosterone at the radius). In addition, lean body mass, % ideal body weight, total body weight, body mass index (BMI) and hours per week of resistance training were positive predictors of BMD. VO(2) max was a negative predictor of BMD. Mean BMD was higher at all skeletal sites in the wrestlers compared with the runners and a comparison group (golfers).

CONCLUSIONS

  Our data suggest that oestradiol levels, BMI, and resistance training are more important determinants of BMD in male collegiate athletes than testosterone.

The effect of supra- and subphysiologic testosterone levels on ligature-induced bone loss in rats--a radiographic and histologic pilot study

BACKGROUND

Testosterone is the primary male sexual hormone, and varying concentrations of the hormone mediated by physiologic, pathologic, or pharmacologic mechanisms may induce large variations in the body. Data regarding the general role of testosterone in mediating inflammation are still inconclusive. Therefore, the purpose of this study is to assess the consequences of supra- and subphysiologic levels of testosterone on ligature-induced bone loss in rats.

METHODS

Three male adult Holtzman rats were used to observe the course of serum testosterone concentration following orchiectomy (Ocx) and testosterone injections. Another 60 rats were randomly assigned to the following groups: (1) sham-operation controls (n = 10); (2) sham-operation and ligature-induced bone loss (n = 10); (3) orchiectomy without ligature (Ocx; n = 10); (4) Ocx and ligature (n = 10); (5) Ocx plus 250 mg/kg body weight intramuscular testosterone esters injection without ligature (Ocx+T; n = 10); and (6) Ocx, T, and ligature (n = 10). The ligatures were placed 30 days postorchiectomy (or sham-operation) and maintained for 15 days. Thereafter, the rats were sacrificed, and their hemimandibles were used for radiographic evaluation of bone loss along with histologic and histometric analyses of gingival tissue.

RESULTS

The results indicated a significant increase in bone loss in the Ocx and Ocx+T groups in the presence and absence of inflammation, respectively. In addition, the Ocx and Ocx+T groups presented increased gingival area accompanying ligature-induced bone loss.

CONCLUSIONS

Both sub- and supraphysiologic testosterone levels may influence bone metabolism, but only subphysiologic levels significantly increase ligature-induced bone loss. Moreover, testosterone has a regulatory effect on the gingival area.

The relationship between sex steroids, bone turnover and vertebral fracture prevalence in asymptomatic men

OBJECTIVE

To examine the association between oestradiol (E2), testosterone (T), SHBG levels and vertebral fractures' (VFs) prevalence in asymptomatic men.

METHODS

The study cohort consists of a population of 112 consecutive men (mean±SD (range) age, weight and BMI were 62.9±9.2 (41-84) years, 75.0±13.8 (45-120) kgs and 26.4±4.7 (18.0-39.6) kg/m(2), respectively). Lateral vertebral fracture assessment (VFA) images and scans of the lumbar spine and proximal femur were obtained using a GE Healthcare Lunar Prodigy densitometer. VFs were defined using a combination of Genant semiquantitative approach and morphometry. Serum levels of T, E2, CTx and osteocalcine were measured. Free androgen index (FAI) and free estradiol index (FEI) were calculated respectively from the ratio of serum T and E2 to SHBG.

RESULTS

Among the 112 men, 38 (33.9%) had densitometric osteoporosis, and on VFA, VFs were identified in 60 (53.5%): 24 men had grade 1 and 36 had grade 2 or 3 VFs (32.1%). Men with VFs weighted less and had a statistically significant lower lumbar spine and total hip BMD and T-scores than those without a VFA-identified vertebral fracture. Levels of osteocalcine, CTx, and SHBG were statistically higher in men with grades 2 and 3 VFs than men with grade 1 VFs and those without VFs whereas FAI and FEI levels were significantly lower. Comparison of patients according to quartiles of SHBG levels showed that men in the highest quartile were older, had a lower lumbar spine and total hip BMD and a higher prevalence of osteoporosis and VFs. They had also higher levels of CTx. Stepwise regression analysis showed that the osteoporotic status and SHBG was independently associated to the presence of VFs.

CONCLUSION

Men with asymptomatic densitometric VFs have lower BMD than subjects without VFs. They have evidence of higher SHBG levels and hence lower free sex steroids as well as increased bone resorption. This study confirms that BMD and CTx are the most important determinant of asymptomatic VFs, and that SHBG is an independent risk factor that must be taken into account.

A new regulator of osteoclastogenesis: estrogen response element-binding protein in bone

The heterogeneous nuclear ribonucleoprotein (hnRNP)-like estrogen response element-binding protein (ERE-BP) competes with estrogen receptor α (ERα) for occupancy of estrogen response elements (EREs). Here we report that ERE-BP potently stimulates osteoclastogenesis. ERE-BP mRNA and protein were found to be expressed ubiquitously in bone. Overexpression of ERE-BP in cultured osteoblasts stimulated expression of the receptor activator of NF-κB ligand (RANKL) and decreased osteoprotegerin (OPG). The effect of ERE-BP on RANKL was shown to be transcriptional in transient transfection assay and competed with via the ER. Constitutive expression of ERE-BP increased the sensitivity of cells toward 1,25-dihydroxyvitamin D(3) stimulation of RANKL expression. In contrast, knockdown of ERE-BP in stromal ST-2 cells decreased basal RANKL promoter activity. Cocultures of ERE-BP lentivirus-transduced ST-2 cells with spleen monocytes induced formation of multinucleated osteoclasts (OCs) characterized by tartrate-resistant acid phosphatase, calcitonin receptors, and functional calcium resorption from bone slices. Although ERα competed with ERE-BP for an ERE in a dose-dependent manner, ERE-BP was an independent and potent regulator of RANKL and osteoclastogenesis. In preosteoclastic RAW cells, overexpression of ERE-BP increased RANK, upregulated NF-κB signaling, and enhanced differentiation toward a mature OC phenotype independent of RANKL. These results identify ERE-BP as a potent modulator of osteoclastogenesis. We hypothesize that ERE-BP may play a critical role in the regulation of bone homeostasis as a modulator of estrogen sensitivity as well as by direct action on the transcription of critical osteoclastogenic genes.