Osteoporosis in men: a cellular endocrine perspective of an increasingly common clinical problem

Bone mineral density in healthy Syrian women measured by dual energyX-ray absorptiometry

Assessment of bone mineral density (BMD) using dual energy X-ray absorptiometry (DXA) technique is considered as a standard technique for diagnosing osteopenia and osteoporosis and evaluating the severity of such diseases. Numerous studies have demonstrated the necessity to establish an ethnicspecific reference data for Bone mineral density measurements. Such data are lacking for the Syrian population. The objectives of this study are (1) to establish BMD reference values in a group of healthy Syrian women using DXA technique, (2) to compare with values from other populations, (3) to study the prevalence of osteopenia and osteoporosis in Syrian women using the manufacturer reference values. A total of 951 healthy Syrian women aged 20-79 years participated in this study. Weight, height, and BMI have been determined. BMD measurements were performed using Lunar Prodigy Advance System (GE). The data were compared with those from other populations. The results have demonstrated the expected decline in BMD with age after peaking at 30-39 years old group. The peak values of the lumbar spine and femur neck were 1.16 (0.12), and 0.95 (0.13) g/cm2, respectively. The results of the Syrian women were compared with those from other populations and the differences were presented. Osteopenia was diagnosed in 35.80% and 60.31% and osteoporosis in 6.23% and 2.72% in lumbar spine and femur neck, respectively, of women 50-59 years of age. These ratios increased to 36.84%, 68.42% and 23.68%, 13.10%, respectively, in the age group more than 59 years. BMD values of the Syrian women were determined for the first time. The results demonstrate the importance of establishing population-specific reference range for BMD values for an accurate assessment of Osteoporosis. High prevalence of osteopenia and osteoporosis was demonstrated in Syrian using the manufacturer reference values.

A1330V polymorphism of the low-density lipoprotein receptor-related protein 5 gene and bone mineral density in Japanese male workers

OBJECTIVES

Both genetic and lifestyle factors have been shown to influence bone mineral density (BMD). We investigated the correlations between BMD and low-density lipoprotein receptor-related protein 5 (LRP5) A1330V (rs3736228) polymorphism, exercise, smoking, and alcohol intake in Japanese male workers.

METHODS

The subjects were 829 male employees (aged 20-59 years) of a large-scale integrated manufacturing facility in Japan. BMD was measured at the nondominant radius by dual-energy X-ray absorptiometry. Lifestyle information was obtained by a questionnaire at the same time, and genomic DNA was isolated from peripheral leukocytes.

RESULTS

Mean ± standard deviation (SD) BMD was 0.557 ± 0.059 g/cm(2). The genotype frequencies of LRP5 gene polymorphism were 51, 42, and 7% for AA, AV, and VV, respectively. Analysis of variance and post hoc Tukey test indicated that mean BMD was significantly lower in subjects with VV genotype than in those with AA genotype (0.540 ± 0.048 versus 0.562 ± 0.062 g/cm(2)). According to multiple linear regression analysis, LRP5 A1330V polymorphism was an independent determinant of BMD, after adjusting for age, body mass index (BMI), and lifestyle variables. Exercise (past or current) also influenced BMD.

CONCLUSIONS

These findings suggest that LRP5 A1330V polymorphism and exercise may influence BMD in Japanese male workers.

Morphology, mechanisms and pathology of musculoskeletal ageing

In general terms, the recognized alterations in circulating humoral factors (hormones, cytokines, growth factors) that occur in ageing, coupled with innate cellular senescence exaggerated by the slow turnover of many connective tissue cell populations and the age-associated alterations in matrix molecule cross-linking, predispose the elderly to altered connective tissue biology. These changes can be profound, leading to poor mobility, altered ability to withstand cold, weakness and an increased risk of falls, fractures and age-associated 'degenerative' diseases, such as osteoarthritis and osteoporosis. As understanding of the causes of altered connective tissue function with age increases, it is becoming clearer that many of the predisposing factors (growth hormone, cytokines, load/life style) are potential targets for improving quality of life in the elderly.

Relationship between angiographically documented coronary artery disease and low bone mass in men

BACKGROUND

The present study aimed to investigate the association between low bone mass (LBM) and coronary artery disease (CAD) in male patients.

METHOD AND RESULTS

The data for 47 men who were screened for osteopenia and osteoporosis with dual energy X-ray absorptiometry and then underwent coronary angiography between February 2005 and May 2006 were retrospectively analyzed. Bone mineral density of the femur neck was stratified as normal (T score >-1.0 SD) or low (T score <-1.0 SD) and CAD was defined as > or = 50% occlusion in at least 1 major coronary artery. Thirty-two patients were found to have angiographically significant CAD. Patients in the LBM group had a significantly higher incidence of CAD. Low bone mass was significantly and positively correlated with the Gensini scores of the patients (r=0.6037, p<0.0001) and was found to be an independent predictor of CAD in multivariate logistic regression analysis (odds ratio: 5.4 [95% confidence interval 1.66 and 17.49]; p=0.0049). Repeated statistical analyses with the acceptance of CAD as coronary artery stenosis >75% confirmed the same results.

CONCLUSION

Low bone mass was significantly associated with angiographically documented CAD in males.

Osteoblast dysfunction in male idiopathic osteoporosis

The etiology of primary osteoporosis in young and middle-aged men is unknown. We have studied osteoblast function in cells derived from men with idiopathic osteoporosis and in control cells from age-matched men with osteoarthrosis. Osteoblasts were isolated from transiliac bone biopsies. Osteoblast function was measured as vitamin D-stimulated osteocalcin production and production of cytokines and factors involved in osteoclast activation and bone formation. Cell proliferation was measured as (3)H-thymidine incorporation. Parathyroid hormone-related peptide (PTHrP) mRNA was measured using reverse-transcriptase polymerase chain reaction. In osteoporotic men, bone mineral density at the femoral neck was correlated to in vitro production of osteocalcin. Osteoblasts from osteoporotic men produced significantly less osteocalcin after vitamin D stimulation but had increased production of macrophage colony-stimulating factor (M-CSF) compared to controls. The osteocalcin response was negatively correlated to production of M-CSF, interleukin-6, and C-terminal propeptide of type I collagen. Basal (3)H-thymidine incorporation was similar in cells from osteoporotic patients and controls. PTHrP (10(-9 )M) significantly increased cell proliferation in control cells but not in osteoporotic cells. Basal PTHrP mRNA levels were significantly higher in osteoporotic cells than in cells from controls. The results are in agreement with previous histomorphologic studies indicating that men with idiopathic osteoporosis have an osteoblast dysfunction with decreased osteocalcin production and increased production of factors stimulating osteoclast activation. This indicates a catabolic cellular metabolic balance leading to negative bone turnover, resulting in osteoporosis. The cause of such cellular dysfunction needs further evaluation.

[Prolactinomas and bone mineral density in men]

Throughout the years evidence has been accumulated on the morbidity of hyperprolactinemia, particularly in terms of bone mineral density decrease. This complication of hyperprolactinemia affects both women and men. In this paper, we analyze aspects related to bone loss in men with hyperprolactinemia due to prolactinomas: prevalence, clinical relevance, physiopathology, diagnosis and the consequences of the treatment of hyperprolactinemia and hypogonadism on bone mineral density.

Normative data of bone Mineral Density in healthy population of Tehran, Iran: a cross sectional study

Background

Osteoporosis is a major problem and is a hidden epidemic disease in the world. Early diagnosis by measurement of Bone Mineral Density (BMD) and treatment can prevent and reduce disease complications, especially fractures. As there is no comprehensive study in Iran, this study designed to assess BMD discrepancy in 20–69 yr Tehran population as well as prevalence of osteoporosis and osteopenia.

Methods

553 people (34% men, 66%women) from 50 Blocks in Tehran randomly selected. The assessment of BMD in spine and femur region performed through DXA method. All subjects clinically examined and their BMIs determined.

Results

The average spinal BMD score in men were more than in women. The peak bone mass of spine bone both in men and women occurred during 20–29 yr and reduction began from the age of 40. At the age of 60 to 69, loose of bone density was 19.6% in lumbar spine and 18.5% in femur of women and also 7.9% in lumbar spine and 14.6% in femur of men. Prevalence of osteoporosis in this age group in lumbar spine and femur was 32.4% and 5.9% in women and 9.4% and 3.1% in men respectively.

Conclusion

In all age groups, peak bone mass was lower than European or American population, whereas the rate of bone loss was as much as the some population and actually this process justifies the prevalence of osteoporosis and osteopenia in Tehran population.

Prevalence of osteopenia in men with prolactinoma

The aim of this cross-sectional study was to analyze bone mineral density (BMD) and prevalence of osteopenia and osteoporosis in 30 men with prolactinoma, and compare them to 22 control subjects. BMD of lumbar spine and femur was evaluated by dual-energy X-ray absorptiometry. PRL, testosterone, estradiol, sexual hormone-binding globulin and free androgen and estrogen indexes (FAI and FEI, respectively) were measured in all the subjects. In patients with prolactinoma, mean values of PRL and testosterone were calculated for the 12-month period that preceded the study. The mean T-score of the four sites analyzed by bone densitometry was lower in men with prolactinoma than in controls (p-values: lumbar spine=0.015, femoral neck <0.0001, trochanter=0.037, total femur=0.036), and 55.6% of the former presented osteopenia or osteoporosis at one or more sites (p =0.035). The lumbar spine was the most seriously affected site, where 29.6% had osteopenia and 14.8% had osteoporosis. By the time of BMD determination, significant associations were found between BMD and PRL, testosterone, FAI, estradiol, FEI, and duration of hypogonadism. Considering the period of 12 months that preceded BMD evaluation, trochanter BMD was associated with mean PRL levels, while there was an association between lumbar spine BMD and mean testosterone levels. However, the multiple regression analysis showed that estradiol was the main determinant of BMD. In conclusion, men with prolactinoma have high prevalence of osteopenia and osteoporosis. Bone loss in such patients is associated with hyperprolactinemia and hypogonadism, and mainly influenced by estrogen.

Association between bone mineral density and LDL receptor-related protein 5 gene polymorphisms in young Korean men

Recently, It has been reported that the LDL receptor-related protein 5 (LRP5) regulates bone formation, and that mutations of the gene cause osteoporosis-pseudoglioma syndrome or high bone mass phenotypes. However, the mutations cannot explain a genetic trait for osteoporosis in the general population because of their rarity. From 219 Korean men aged 20-34 yr, we looked for six known polymorphisms causing amino acid changes in the LRP5 coding region, and investigated their association with bone mineral density (BMD) at the following anatomical sites: lumbar spine (L2-L4) and the left proximal femur (femoral neck, Ward's triangle, trochanter and shaft). We found that the Q89R polymorphism was significantly associated with BMD at the femoral neck and Ward's triangle (p=0.004 and <0.001, respectively). However, after adjusting for age, weight and height, a statistically significant association only occurred at the Ward's triangle (p=0.043), and a marginal association was observed at the femoral neck (p=0.098). No A400V, V667M, R1036Q and A1525V polymorphisms were found, and no statistically significant association was found between the A1330V polymorphism and BMD at any sites. Although we failed to demonstrate a clear association between the LRP5 polymorphism and peak bone mass in young men, the present study suggests that larger-scale studies on the Q89R polymorphism need to be performed.

Stem cells as vehicles for orthopedic gene therapy

Adult stem cells reside in adult tissues and serve as the source for their specialized cells. In response to specific factors and signals, adult stem cells can differentiate and give rise to functional tissue specialized cells. Adult mesenchymal stem cells (MSCs) have the potential to differentiate into various mesenchymal lineages such as muscle, bone, cartilage, fat, tendon and ligaments. Adult MSCs can be relatively easily isolated from different tissues such as bone marrow, fat and muscle. Adult MSCs are also easy to manipulate and expand in vitro. It is these properties of adult MSCs that have made them the focus of cell-mediated gene therapy for skeletal tissue regeneration. Adult MSCs engineered to express various factors not only deliver them in vivo, but also respond to these factors and differentiate into skeletal specialized cells. This allows them to actively participate in the tissue regeneration process. In this review, we examine the recent achievements and developments in stem-cell-based gene therapy approaches and their applications to bone, cartilage, tendon and ligament tissues that are the current focus of orthopedic medicine.

Systemically administered rhBMP-2 promotes MSC activity and reverses bone and cartilage loss in osteopenic mice

Osteoporosis is a disease manifested in drastic bone loss resulting in osteopenia and high risk for fractures. This disease is generally divided into two subtypes. The first, post-menopausal (type I) osteoporosis, is primarily related to estrogen deficiency. The second, senile (type II) osteoporosis, is mostly related to aging. Decreased bone formation, as well as increased bone resorption and turnover, are thought to play roles in the pathophysiology of both types of osteoporosis. In this study, we demonstrate in murine models for both type I (estrogen deficiency) and type II (senile) osteopenia/osteoporosis that reduced bone formation is related to a decrease in adult mesenchymal stem cell (AMSC) number, osteogenic activity, and proliferation. Decreased proliferation is coupled with increased apoptosis in AMSC cultures obtained from osteopenic mice. Recombinant human bone morphogenetic protein (rhBMP-2) is a highly osteoinductive protein, promoting osteogenic differentiation of AMSCs. Systemic intra-peritoneal (i.p.) injections of rhBMP-2 into osteopenic mice were able to reverse this phenotype in the bones of these animals. Moreover, this change in bone mass was coupled to an increase in AMSCs numbers, osteogenic activity, and proliferation as well as a decrease in apoptosis. Bone formation activity was increased as well. However, the magnitude of this response to rhBMP-2 varied among different stains of mice. In old osteopenic BALB/c male mice (type II osteoporosis model), rhBMP-2 systemic treatment also restored both articular and epiphyseal cartilage width to the levels seen in young mice. In summary, our study shows that AMSCs are a good target for systemically active anabolic compounds like rhBMP-2.

Influence of cortisol, gonadal steroids and an energy deficit on biochemical indicators of bone turnover in Swine

In the pig a high growth potential seems to favour a disposition for skeletal problems. Hormones of growth hormone (GH)/insulin-like growth factor (IGF)-I axis as well as cortisol and gonadal steroids are endocrine determinants of the anabolic potential but their effects on bone turnover in pigs have not been described. Thus, key hormones were either infused for 7 days (cortisol, 5alpha-dihydrotestosterone (DHT), oestradiol) or influenced by Metyrapone (inhibition of cortisol synthesis) or energy deficit (increasing GH). Each treatment was carried out in six growing barrows/treatment. Bone turnover was characterized by daily measurements indirect parameter of osteoblastic and osteoclastic activity, osteocalcin (OC) and tartrate-resistant acid phosphatase (TRAP) respectively. All treatments except cortisol infusion seemed to favour bone formation, as they led either to a pronounced increase in OC (Metyrapone: +14%) or to significantly reduced TRAP (DHT: -9%, E2: -17%, energy deficit: -25%) followed by significantly higher OC (DHT: +9%, E2: +6%, energy deficit: +18%). Cortisol infusion affected bone loss mainly by a severe inhibition of osteoblastic activity (OC: -61%). Some reactions are explained by direct effects of the infused gonadal steroids on bone cells (inhibition of osteoclasts) or of the experimentally modified cortisol levels (inhibition of osteoblasts by cortisol). Other effects seem to be mediated by concomitant changes of IGF-I (inhibition of osteoclasts after energy deficit or cortisol) and GH-secretion (increased osteoblastic activity during energy deficit), respectively. Consequences for co-ordinated bone turnover are discussed.

Soy protein supplementation increases serum insulin-like growth factor-I in young and old men but does not affect markers of bone metabolism

Recent studies suggest that soy protein (SP) protects bone in women; however, its effects on bone metabolism in men have not been investigated. Healthy men (59.2 +/- 17.6 y) were assigned to consume 40 g of either SP or milk-based protein (MP) daily for 3 mo in a double-blind, randomized, controlled, parallel design. Serum insulin-like growth factor-I (IGF-I), which is associated with higher rates of bone formation, was greater (P < 0.01) in men supplemented with SP than in those consuming MP. Serum alkaline phosphatase and bone-specific alkaline phosphatase activities, markers of bone formation, and urinary deoxypyridinoline excretion, a specific marker of bone resorption, were not different between the SP and MP groups. Furthermore, because substantial reductions in bone density occur in men at approximately 65 y of age, data were analyzed separately for men >/=65 y and those <65 y of age. The response to protein supplementation was consistent in the two age groups. The effects of SP on serum IGF-I levels suggest that SP may positively influence bone in men. Longer-duration studies examining the effects of SP or its isoflavones on bone turnover and bone mineral density and content in men are warranted.

Hormonal regulation of androgen receptor messenger ribonucleic acid expression in human tooth pulp

Tooth pulp contains steroid receptors and therefore is likely to respond to steroids. Steroids and cytokines together can alter steroid receptor content in many tissues; thus, similar mechanisms may exist in tooth pulp. In this study, reverse-transcription/polymerase chain-reaction was used to screen human pulp for the mRNAs encoding receptors for androgen (AR), estrogens (ERbeta), and hepatocyte growth factor (HGF: c-Met). AR mRNA content was greater in male pulp vs. female pulp in all age groups. In both genders, AR mRNA content diminished with age. In pulp cell cultures, androstenedione, estradiol-17beta, and HGF each stimulated AR mRNA accumulation. Testosterone inhibited, whereas 5alpha-dihydrotestosterone did not affect, AR mRNA content. ERbeta was not hormonally altered in pulp cell cultures. By showing steroid- and cytokine-orchestrated regulation of AR mRNA in vitro, it is possible that age- and/or pathogen-dependent changes in available steroids and cytokines can affect any androgen-responsiveness of pulp.

IGF-1 in gynaecology and obstetrics: update 2002

Recent discoveries on endocrine, paracrine and autocrine involvement of insulin-like growth factor-1 (IGF-1) in the proliferation of many tissues raised the attention of its role in reproduction and in the growth of various cancers as well as of benign proliferations. The intention of this article is to focus on IGF-1 in the field of gynaecology. Perimenopausal women who exhibit high IGF-1 and low IGF binding protein (IGFBP) levels, like IGFBG-3, have an increased risk of developing breast cancer. A higher risk for cervical, ovarian and endometrial cancer is related to high IGF-1 levels in post- and premenopausal women. It has been shown that myomas, by far the most common benign uterine tumor in women, grow in the presence of IGF-1, in vitro as well as in vivo. Studies show that IGF-1 is involved in the differentiation of various reproductive tissues, like endometrium and ovarian tissues. Patients suffering from polycystic ovary syndrome (PCO) frequently show insulin resistance accompanied by an increase of IGF-1 in plasma. Plasma IGF-1 levels are higher in cases of severe endometriosis, however, in endometriosis and in PCO IGF levels locally in the endometrium are reduced, what might explain infertility. Recently, it was shown that IGF facilitates the implantation of the human embryo in the endometrium during IVF. Implantation is a paradox where different immune systems have to collaborate to make implantation and survival of the pregnancy possible. IGF seems to be the starter molecule so that the two epithelia can fuse. A disturbance can result in complications during pregnancy i.e. spontaneous miscarriage, preeclampsia as well as defects of the embryo. Therefore, IGF is a useful marker in successful pregnancy as well. A better mechanistic understanding of IGF-1 action on the cellular level not only provides more elegant mechanistic explanations for the scientist, but the practitioner might find it interesting to utilize its diagnostic potential as a marker for various diseases. The relation between systemic IGF levels and local tissue IGF-1 levels has not yet been determined for all conditions.