Age-related changes of vertebral bone mineral density in Russian population]

Vertebral trabecular bone mineral density (BMD) was measured by quantitative computed tomography (QCT) in 1061 subjects (610 females and 451 males aged from 7 to 91 and from 12 to 89, respectively) with known history of diseases or taking medicines affecting bone metabolism. Peak BMD values in our patients were observed at the age of 20-29 years with further gradual decrement in men and more steep in women. Negative relationship between BMD and age was r = -0.991 for men and r = -0.968 for women. Analyzing BMD changes by decades we observed the largest decrement in men after 60 (13.1% for 60-69 and 14.1% for 70-79 years of age) and in women after 50 (22.5% for 50-59, 22.1% for 60-69 and 20.8% for 70-79 years) which was most probably due to decline in sex hormones production that is known to significantly influence bone metabolism. This was confirmed by BMD values three-phase approximation in women showing the lowest rate of calcium loss by trabecular bone in reproductive period (1.9 mg/cm3/yr) and the highest in perimenopause (3.98 mg/cm3/yr). Annual calcium loss in postmenopause was 2.22 mg/cm3.     

Traditional CVD risk factors and socio-economic deprivation in Roma minority population of Croatia

Researches into health inequalities consistently show disadvantages in health status, morbidity and mortality for various ethnic minority groups. Current knowledge about prevention of cardiovascular diseases (CVD) mainly derives from studies carried out in populations of European origin while the evidences involving Roma population are scarce. Roma, an ethnic minority of northern Indian origin, live in many countries throughout the world and are well known for preserved traditions and resistance to assimilation. They are most often marginalized economically, spatially, politically and in terms of culture. In order to assess the health status and health-related lifestyle attributes, a multidisciplinary anthropological and epidemiological community-based study was carried out including a total of 423 members of the Bayash Roma minority population living in two regions of Croatia (144 men and 279 women, aged 18-84 yrs). Hypertension (HT) was found in 24.8% Bayash Roma (21.5% men and 26.5% women) using standard diagnostic criteria (i.e. BP > or = 140/90 mm Hg or taking antihypertensive therapy). The prevalence increases from 5.9% in the age group 18-34 yrs; 35.0% in the age group 35-64 yrs, and 51.4% in the age group 65+ yrs. The prevalence of hypertension in the Bayash Roma is almost half of the magnitude of what is usually reported for the general population of Croatia. It is also lower when compared with other European populations and this finding is not due to comparatively younger average age of the Bayash sample. The significant association of hypertension with age and BMI was confirmed in this study and the importance of non-traditional SES-related CVD risk factors was highlighted. Smoking is a part of traditional Roma life-style and with 70% of smokers almost the entire population is equally exposed to this risk factor in their family environment. Since homogenously distributed, this risk factor did not show to be a significant predictor of hypertension. The extent to which hypertension is influenced by traditional CVD risk factors as well as by some SES indicators was also assessed using a forward stepwise method of the multivariate logistic analysis. Each risk factor was explored as quantitative variable as well as qualitative one using various cut-offs. The best model showed to be the one having age and BMI presented as quantitative variables and sex, region, smoking status, income and schooling years as categorical ones; with cut-off 3 for number of income sources and 8 for the number of schooling years. In spite of the low prevalence of hypertension, the presented results are showing that Bayash Roma are bearing a high CVD risk factors load. We expect that with westernization of their life-style and along with increase of the economic power, the proportion of CVD in population of Bayash Roma will also increase. Therefore, it is important to recognize the need for early cardiovascular disease risk factors prevention in this minority population.     

Influence of the incoming solar radiation on the bone mineral density in the female adult population in Croatia

The relationship between the bone mineral density (BMD) in Croatian female adults and the average incoming solar radiation at the ground was investigated. The study included 387 volunteers of average age of 60 years from three different towns: Pula (n = 128, age from 35 to 76), Krapina (n = 141, age from 43 to 77), and Zagreb (n = 118, age from 32 to 79). Apart from the different lifestyle, each of above towns is characterized by different incoming solar radiation, where values of 503.3 kJ cm-2, 471.2 kJ cm-2 and 436.3 kJ cm-2 correspond to average annual radiation at the ground for Pula, Krapina and Zagreb, respectively. Heel BMD was measured by clinical bone sonometer (Sahara). On the average the BMD was highest for Pula (0.469 g cm-2) and the lowest for Zagreb (0.433 g cm-2). Similarly, the percentage of normal bones was the highest for Pula (46.1%) and the lowest for Zagreb (32.2%). Osteopenic bones were the most frequent for Zagreb (61.0%), while corresponding figures for Pula and Krapina were 46.9% and 43.6%, respectively. Osteoporosis varied from 6.8% in Zagreb to 11.4% in Krapina. A test of independence by contingency table confirmed at the significance level alpha = 0.05 that probability of normal bone occurrence increases with the increase of incoming solar radiation. Results of the multiple regression analysis suggest the dependence of BMD on woman's age and weight, and incoming solar radiation at the place of habitation.     

Volumetric and projective bone mineral density

Projectional bone mineral density measurement so far used extensively in radiogrammetry and single and dual source absorptiometry is confronted with a serious limitation for the accurate evaluation of true density artifactually providing higher values along with the increase of body size and bone depth on account of the omission of one dimension. Computed tomography is capable of measuring true volumetric density and also accomplishes a separate measurement of trabecular and cortical bone especially on application to the distal and mid-radius with abundant cortical bone in peripheral computed tomography (pQCT). New lines of information may be obtained by such separate trabecular and cortical bone measurement in decreases of bone density due to various causes, estrogen withdrawal, corticosteroid, diabetes mellitus, renal failure, etc. Dynamic analysis of the result of pQCT may also make it possible to assess bone strength and resistance to fracture.     

The pathophysiological implications of circulating androgens on bone mineral density in a normal female population

In this cross-sectional study performed on 147 healthy or osteoporotic, but otherwise normal premenopausal (n = 26 and n = 13, respectively) or postmenopausal (n = 40 and n = 68, respectively) women aged 40.1+/-9.9 and 61.9+/-8.9 years, respectively (range 20-82 years), serum ovarian and adrenal sex steroids and their relationship to bone mineral density (BMD) were evaluated. The levels of dehydroepiandrosterone sulfate (DHEAS), dehydroepiandrosterone (DHEA), androstenedione (AD), and estradiol correlated positively with BMD at the hip and spine as did serum testosterone with BMD at the spine. An inverse relationship was found between sex hormone binding globulin (SHBG) levels and BMD at the spine and hip. After adjustment for age, body mass, and sex steroid confounders, the bioavailable testosterone value (but not the DHEAS, DHEA, AD, or SHBG) values was demonstrated to be an independent determinant of BMD at the spine (beta 0.18, P<0.02) and hip (beta 0.24, P<0.02). Similarly, estradiol was found to be an independent determinant of BMD at the spine (beta 0.25, P<0.007). However, only SHBG levels (but not other steroid parameters) correlated positively with indices of bone remodeling, namely, serum osteocalcin and cross-linked telopeptide of type I collagen (ICTP). The present study suggests that a major decline in index of free testosterone (testosterone/SHBG) may influence the development of female osteoporosis. The clinical significance of circulating SHBG levels in the assessement of bone metabolic turnover remains to be established.     

Genetic regulation of bone mineral density in mice

Peak bone mass is a major determinant of risk of osteoporotic fracture. Family and twin studies have found a strong genetic component to the determination of bone mineral density (BMD). However, BMD is a complex trait whose expression is confounded by environmental influences and polygenic inheritance. The number, locations and effects of the individual genes contributing to natural variation in this trait are all unknown. The extreme difficulty of dissecting out environmental factors from genetic ones in humans has motivated the investigation of animal models. Genetically distinct animal strains raised under strict environmental control are critical tools for defining genetic regulation. The availability of inbred strains, combined with its relative fecundity, has established the mouse as the best model system for the study of mammalian genetics and physiology. Importantly, genes identified in murine analyses can usually be readily mapped to particular human chromosomal regions because of the high degree of synteny that exists between the mouse and human genomes. We employed quantitative trait locus (QTL) analysis to examine peak BMD in 24 recombinant inbred (RI) mouse strains, derived from a cross between C57BL/6 (B6) and DBA/2 (D2) progenitors (BXD RI). The distribution of BMD values among these strains clearly indicated the presence of strong genetic influences, with an estimated narrow sense heritability of 35%. The differences in peak whole body BMD in the BXD strains were integrated with a large database of genetic markers previously defined in the RI BXD strains to generate chromosome map sites for QTL locations. This QTL analysis provisionally identified a number of chromosomal sites linked to BMD. In the second phase of our BMD QTL mapping efforts, we used three independent mouse populations (all derived from B6 and D2 progenitor strains) to confirm and narrow the genetic locations of 4 QTLs (on chromosomes 1, 2, 4, and 11) that strongly influence the acquisition of peak BMD in mice. Using a novel, fine-mapping approach (recombinant inbred segregation testing), we have succeeded in narrowing two of the BMD-related chromosomal regions and in the process eliminated a number of candidate genes. The homologous regions in the human genome for each of these murine QTLs have been identified in recent human genetic studies. In light of this, we believe that findings in mice should aid in the identification of specific candidate genes for study in humans.     

Non-invasive method for measuring bone mineral density

Measurement of bone mineral density (BMD) using dual energy X-ray absorptiometry is the basis of the definition of osteoporosis. Accuracy, precision and sensitivity of the method are good enough for clinical use. Prospective studies have shown that there is a gradient of risk between the decrease in BMD, related to age and hormonal insufficiency, and the increase in the incidence of fracture. Thus, therapeutic decision is based on both BMD and clinical risk factors that contribute to fracture risk.     

Comparison between quantitative X-ray imaging,dual energy X-ray absorptiometry and microCT in the assessment of bone mineral density in disuse-induced bone loss

Objectives:

We recently introduced a new methodology called quantitative X-ray imaging (qXRI) to investigate bone mineral density in isolated rodent bones. The aims of the present study were to compare DXA and microCT with qXRI in a rat model of disuse osteoporosis.

Methods:

Fourteen Copenhagen rats were injected with a single dose of botulinum toxin (BTX - 2 UI) in the right Mus quadriceps femoris. The left hindlimb serves as control. Areal BMD and vBMD were determined with a Hologic Discovery-W device and a Skyscan 1172 microcomputed tomograph (microCT). Absorbing material density (AMD) was determined on digitized X-ray images obtained with a Faxitron M020 device.

Results:

All three methods highlighted significant lower values for aBMD, vBMD and AMD in trabecular and cortical bone in the BTX-injected side. In trabecular bone, aBMD, vBMD and AMD were significantly correlated with BV/TV. In cortical bone, only aBMD and vBMD were significantly correlated with cortical bone mass On the other hand, only AMD was significantly correlated with the mechanical parameters bending strength and bending modulus.

Conclusions:

qXRI is a rapid and cheap method to assess trabecular bone mass in isolated rodent bones and can be used as a surrogate for the densitometry of small animals.     

Effects of physical training on bone mineral density and bone metabolism

The purpose of this study was to examine the influences of long-term walking training and walking and jumping training on bone mineral density (BMD) and bone metabolism. Data from 28 healthy premenopausal women was assessed. The subjects were divided into the walking group (WG; 17 women mean+/-SE age 35+/-2 years), and the walking and jumping group (WJG; 11 women mean+/-SE age 39+/-1 years). BMD was measured in the lumbar spine and proximal femur using dual energy X-ray absorptiometry (DXA). As markers of bone metabolism, this study was to measure bone formation markers, bone-alkaline phosphatase (B-ALP: measured by enzyme immunoassay/EIA) and osteocalcin (BGP: by radioimmunoassay/RI) as well as bone resorption markers, parathyroid hormone (PTH: measured by/RI) and type I collagen cross-linked N-telopeptides (NTx: by EIA). Despite the significant decrease in body weight (p<0.05), no corresponding decrease in BMD was observed. Moreover, no significant difference in bone markers BGP, PTH, and NTx was observed. B-ALP was significantly increased (p<0.05) after one year, and the rate of this increase was greater in the WJG than in the WG. It is thus concluded that walking training for one year is beneficial for the promotion of bone formation, and that jumping stimulus maintain BMD effectively.     

Association between oxidative stress and bone mineral density

Free radicals have been shown to be involved in bone resorption in vitro and in rodents. We studied the effect of oxidative stress on bone mineral density (BMD) in 48 women and 53 men from a population-based study. The levels of 8-iso-PGF(2alpha) (a major F(2)-isoprostane and a biomarker of oxidative stress) and a control, 15-keto-dihydro-PGF(2alpha) (a biomarker of inflammatory response), were measured in urinary samples and their association with BMD and quantitative ultrasound (QUS) measurements were examined. In multivariate linear regression analyses, 8-iso-PGF(2alpha) levels were negatively associated with both BMD and QUS. In contrast, no association was found for 15-keto-dihydro-PGF(2alpha). Our findings establish a biochemical link between increased oxidative stress and reduced bone density and provide a rational for further studies investigating the role of pro- and antioxidants in osteoporosis.     

大豆异黄酮对去卵巢大鼠骨密度及骨代谢影响的实验研究

目的 探讨大豆异黄酮对去卵巢大鼠骨丢失的防治作用及其作用机理。方法 选用卵巢切除大鼠所诱发的骨质疏松模型,给与大豆异黄酮治疗。三个月后测定大鼠骨密度及骨代谢相关生化指标。结果 大豆异黄酮可提高卵巢切除大鼠的骨密度及血清雌激素水平,降低尿钙（Ca),尿磷（P）及尿羟脯氨酸（HOP）的排泄,同时降低血清总碱性磷酸酶（ALP）,骨碱性磷酸酶（BALP）,及抗酒石酸酸性磷酸酶（TRACP）的活性,还可使血清骨钙素（BGP）的浓度降低,促使卵巢切除大鼠子宫的相对重量增加,其作用与剂量相关。结论 小剂量大豆异黄酮有类似雌激素样作用,可有效防治卵巢切除大鼠的骨量丢失,其作用机制可能是通过降低骨转换率实现的。     

Height, bone mineral density and bone markers in congenital adrenal hyperplasia.

AIM: To evaluate height, bone growth, areal bone mineral density (aBMD), volumetric bone mineral density (vBMD) and markers of bone turnover in a group of patients affected by congenital adrenal hyperplasia (CAH). PATIENTS: There were 50 patients (23 males, 27 females), aged 1-28 years, affected by CAH due to 21-hydroxylase deficiency: 27 with the salt-wasting (SW); 14 with the simple virilizing (SV), and 9 with the nonclassical (NC) forms. METHODS: Bone morphometry was evaluated with the metacarpal index (MI) and lumbar aBMD and vBMD (L2-L4) by dual energy X-ray absorptiometry. Serum osteocalcin was used as a marker of bone formation, while urinary cross-linked N-telopeptides of type-I collagen and free deoxypyridinoline levels were evaluated as indexes of bone resorption. RESULTS: The height standard deviation score (SDS) was -0.41 +/- 1.4 in SW patients, -0.01 +/- 1.9 in SV patients, and -0.01 +/- 2.3 in NC patients. There was no significant difference among groups and against zero. The MI SDS was also not different between groups and against zero. aBMD was significantly lower in the pubertal patients compared with normal values, but only when patients with the SW and SV forms were considered together (p < 0.05). vBMD was significantly reduced in all patients with the classical form. Bone markers were not different in patients and controls. CONCLUSION: Our study shows that normal height can be attained in CAH patients; however, an impairment in bone growth and mineralization may be found in adolescents and young adults affected by the classical form.     

Genetic and environmental correlations between bone mineral density and bone size in Caucasians

To explore the magnitude of common genetic and environmental effects shared by bone mineral density (BMD) and bone size (BS) in a large sample of 4,489 subjects (2,667 females and 1,822 males) from 582 Caucasian pedigrees, we performed a bivariate variance decomposition analysis to evaluate genetic correlation (rhoG), environmental correlation (rhoE), and phenotypic correlation (rhoP) between BMD and BS at the spine and hip, as well as their "synthesized" skeletal site (bone mineral density principal component, bone size principal component) generated by principal components analysis. Significant rhoG, rhoE, and rhoP were detected, but the shared genetic influence on BMD and BS was only 21%, 1.3%, and 11.6% at the spine, hip, and their joint variable, respectively. The results suggest that it may be important to choose both BMD and BS, especially at the hip, as surrogate phenotypes for osteoporosis genetic studies in Caucasians.     

Bone mineral density and bone turnover in hyperprolactinaemia of various origins

INTRODUCTION: Osteopenia and osteoporosis because of hyperprolactinaemia caused by prolactinoma may be followed by an increased risk of fracture. There are no data on the bone effects of functional hyperprolactinaemia. The aim was to assess the influence of hyperprolactinaemia of various origins on bone turnover and density in different skeletal sites. MATERIAL AND METHODS: The study was carried out in 75 women (aged 30.53 +/- 7.8): Group I--32 women with prolactinoma and Group II--43 women with functional hyperprolactinaemia. Both groups of patients were subdivided into those with hypogonadism and those with normal gonadal function. The control group consisted of 29 healthy women aged (33.59 +/- 4.7). In all subjects PRL and bone turnover markers (BAP, OC, ICTP) were studied. BMD measurements (lumbar spine, forearm, proximal femur and total body) were carried out using DXA. RESULTS: Higher PRL concentrations were observed in patients than in controls. The values of bone turnover markers (BAP, ICTP) were shown to be higher in patient groups and subgroups than in controls. In patients with prolactinoma lumbar spine BMD was lower than in patients with functional hyperprolactinaemia and controls. Total body BMD was also lower, albeit to a lesser extent. CONCLUSIONS: Hyperprolactinaemia caused by prolactinoma in women influences bone metabolism unfavourably, more by the impact on the activity of bone turnover markers than on BMD. This provides an opportunity for earlier assessment of bone metabolism disturbances before the BMD changes can be observed. Functional hyperprolactinaemia does not determine such a harmful effect on bone metabolism as hyperprolactinemia due to prolactinoma.     

Anorexia nervosa: hypogonadotrophic hypogonadism and bone mineral density

Anorexia nervosa is a chronic illness that involves a reduction in caloric intake, loss of weight and amenorrhoea, either primary or secondary. In addition to prolonged amenorrhoea, osteopenia and osteoporosis are the most frequent complications. Patients exhibit an alteration in the hypothalamic-pituitary-gonadal axis, which is responsible for the menstrual disorders. The increase in gonadotrophin secretion that can be observed after ponderal recuperation suggests that malnutrition could be the most important mechanism involved in the decrease in gonadotrophin secretion. The loss of fat tissue, as a consequence of the restriction of nutrients, has been associated with hypoleptinaemia, abnormal secretion of peptides implicated in food control (neuropeptide Y, melanocortins and corticotrophin-releasing hormone, among others) and diminution of the amount of total body fat. Despite oestrogen therapy, the severe loss of bone mass may progress. Other factors such as weight loss, duration of amenorrhoea and low insulin-like growth factor-I (IGF-I) levels could contribute to the loss of bone mass in women with anorexia nervosa. The recuperation of weight and, in particular, the amount of total body fat could lead to the spontaneous recuperation of menstruation.