Association between body weight and proximal tibial bone mineral density after bilateral total knee arthroplasty

Background

Proximal tibial bone mineral density (BMD) has been studied for its potential impact on subsidence and loosening of the tibial component after total knee arthroplasty (TKA). However, no known studies of proximal tibial BMD after TKA have evaluated the effect of major impact factors such as body weight (BW), muscle strength, and level of activity. We aim to determine whether factors such as level of activity, quadriceps strength, BW, gender, age, and prosthetic design affect proximal tibial BMD over the mid- to long-term following TKA.

绝经后妇女骨质疏松患者血清IGF-1、IGFBP-3与骨密度及骨代谢指标的关系

目的： 探讨胰岛素样生长因子-1（IGF-1）和胰岛素样生长因子结合蛋白-3（IGFBP-3）与绝经后妇女骨密度及骨代谢指标之间的关系。方法： 通过检测90例绝经后妇女骨质疏松患者及70例绝经后骨量正常的健康对照组血清IGF-1、IGFBP-3、骨钙素（BGP）、I型胶原异构C端肽（β-CTX）、雌激素（E₂）、降钙素（CT）、甲状旁腺激素（PTH）、钙（Ca）、磷（P）等指标，然后同用双能X线骨密度仪检测的两组研究对象的腰椎（L2-L4）侧位、左股骨颈骨密度进行比较。结果： 绝经后骨质疏松组妇女腰椎、股骨颈骨密度显著低于对照组（均P<0.01）；血清IGF-1、IGFBP-3、E₂、CT、BGP水平均低于对照组（均P<0.01）；血清β-CTX、PTH均高于对照组（均P<0.01），血清Ca、P两组之间无差异（均P>0.05）。骨质疏松组和对照组腰椎侧位、左股骨颈BMD均与IGF-1、IGFBP-3、E₂、BGP、CT水平呈正相关，与β-CTX、PTH水平呈负相关，而与血钙、血磷无明显关系。结论： IGF-1、IGFBP-3、E₂、BGP、CT、β-CTX、PTH血清水平与腰椎、左股骨质具有明显的相关性，通过检测上述指标可考虑作为筛查绝经后妇女是否容易患有骨质疏松症的一项有价值的生化参考指标。     

运动联合福善美对去卵巢大鼠骨密度和神经传导的影响

目的: 观察运动是否可增强福善美对卵巢切除大鼠骨质疏松的治疗作用。方法: 将90只6月龄雌性SD大鼠随机分为假手术组(sham,18只)和卵巢切除模型组(OVX,72只)。大鼠卵巢切除8周后,测定大鼠第4腰椎骨密度(BMD)和血清雌二醇含量。随后,存活的OVX大鼠分为模型组(OVX)、福善美治疗组(OVX+FOX)、运动治疗组(OVX+EX)和福善美与运动联合治疗组(OVX+FOX+EX),分别给予1 mg·kg^-1·d^-1福善美灌胃和(或)跑台运动干预治疗12周后,双能X线骨密度仪测定各组大鼠第4腰椎BMD;肌电图机检测大鼠左侧股神经传导速度(MCV)、运动末端潜伏期(ML)和复合肌肉动作电位(CMAP);ELISA法测定大鼠血清Ⅰ型前胶原羧基端前肽(PICP)及Ⅰ型胶原羧基端交联端肽(ICTP)含量。结果: 卵巢切除大鼠福善美和(或)运动干预治疗12周后,OVX组与sham组相比,BMD显著降低(P<0.05),血清PICP和ICTP明显增高(P<0.05),左侧股神经ML未见明显改变。福善美和运动均可显著提高骨质疏松大鼠BMD,降低ICTP;福善美可显著降低骨质疏松大鼠ICTP,而运动对ICTP无明显影响。运动可明显缩短模型组左侧ML(P<0.05),福善美对ML无显著改善作用。运动与福善美联合对BMD、PICP、ICTP及ML的改善作用较两者单用效果显著(P<0.05);福善美与运动两治疗组间未见明显差异。各组大鼠左侧股神经MCV和CMAP未见明显差异。2×2析因设计的方差分析显示,福善美与运动2种处理方式之间不存在交互作用(P>0.05)。结论: 福善美和运动可能通过抑制破骨细胞的骨吸收而抑制大鼠卵巢切除对骨密度的影响。     

Testosterone enhances estradiol''s effects on postmenopausal bone density and sexuality

To investigate the role of androgens in increasing bone density and improving low libido in postmenopausal women, we have studied the long-term effects of estradiol and testosterone implants on bone mineral density and sexuality in a prospective, 2 year, single-blind randomised trial. Thirty-four postmenopausal volunteers were randomised to treatment with either estradiol implants 50 mg alone (E) or estradiol 50 mg plus testosterone 50 mg (E&T), administered 3-monthly for 2 years. Cyclical oral progestins were taken by those women with an intact uterus. Thirty-two women completed the study. BMD (DEXA) of total body, lumbar vertebrae (L1–L4) and hip area increased significantly in both treatment groups. BMD increased more rapidly in the testosterone treated group at all sites. A substantially greater increase in BMD occurred in the E&T group for total body (P < 0.008), vertebral L1–L4 (P < 0.001) and trochanteric (P < 0.005) measurements. All sexual parameters (Sabbatsberg sexual self-rating scale) improved significantly in both groups. Addition of testosterone resulted in a significantly greater improvement compared to E for sexual activity (P < 0.03), satisfaction (P < 0.03), pleasure (P<0.01), orgasm (P < 0.035) and relevancy (P < 0.05). Total cholesterol and LDL-cholesterol fell in both groups as did total body fat. Total body fat-free mass (DEXA, anthropometry, impedance) increased in the E&T group only. We concluded that in postmenopausal women, treatment with combined estradiol and testosterone implants was more effective in increasing bone mineral density in the hip and lumbar spine than estradiol implants alone. Significantly greater improvement in sexuality was observed with combined therapy, verifying the therapeutic value of testosterone implants for diminished libido in postmenopausal women. The favourable estrogenic effects on lipids were preserved in women treated with T, in association with beneficial changes in body composition.     

乌鲁木齐市维吾尔族青年与老年女性血清微量元素及骨密度的对比

 背景：雌激素通过影响骨骼细胞的新陈代谢而促进微量元素在骨骼中的储存,影响骨密度的变化。 目的：比较乌鲁木齐市维吾尔族青年女性与老年女性骨密度及血清中微量元素的差异。 方法：使用MEDILINK生产的双能X射线骨密度测量仪对乌鲁木齐市维吾尔族30-40岁(青年女性组)与60-70岁(老年女性组)女性各30人进行骨密度测定;使用美国贝克曼库尔特生产的Unicel Dxc 800 Synchron生化检验仪查血清中的微量元素钙、磷、镁、铁、铜、锌含量。比较不同年龄段女性血清中微量元素及骨密度水平。 结果与结论：维吾尔族青年女性组骨密度显著高于老年女性组(P < 0.001);维吾尔族青年女性组血清微量元素锌显著低于老年女性组(P < 0.001);其余的血清微量元素钙、磷、镁、铁、铜两组之间差异无显著性意义(P > 0.05)。结果表明维吾尔族女性不同年龄段骨密度随体内血清中部分离子元素的改变有较大的改变。 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

Serum leptin levels,bone mineral density and osteoblast alkaline phosphatase activity in elderly men and women

Although primarily secreted by adipose cells, leptin, a polypeptide hormone that influences body weight, satiety and lipid metabolism, and its receptor are also expressed in human osteoblasts. Leptin plays a role in the central, hypothalamic modulation of bone formation, as well as locally within the skeleton by enhancing differentiation of bone marrow stroma into osteoblasts and inhibiting its differentiation into osteoclasts and adipocytes. The purpose of this investigation was to compare serum leptin values in 100 postmenopausal women (age 62-97) and 31 men (age 72-92) to bone mineral density (BMD) measurements made by dual X-ray absorptiometry and additionally to biochemical markers of bone resorption and formation, including crosslinked collagen N-telopeptides (NTx), aminoterminal extension procollagen propeptides (PINP) and bone-specific alkaline phosphatase (bAP). The circulating level of leptin directly correlated with body mass index (BMI) (r=0.61-0.78, P<0.001) and was modestly, but significantly and positively associated with bAP activity (r=0.24-0.33, P<0.01) in the sera of men and women after adjustment for BMD, age and BMI. The association of circulating leptin levels with bAP, a specific marker of osteoblast activity suggests that leptin levels influence osteoblast activity in vivo in elderly women and men.     

Hip bone mineral density is improved by high-impact aerobic exercise in postmenopausal women and men over 50 years

Fifteen men and women (six men) between the ages of 50 and 73 years were recruited to begin keep-fit classes. They were matched for sex, age, menopausal status and mass to 15 non-exercising controls. The keepfit classes were two to three times a week and included high-impact exercise, including step and jumping exercises specifically to load the proximal femur and spine. Proximal femur, lumbar spine and total body bone mineral density (BMD) were measured at 0 and 12 months. Urinary pyridinoline (Pyr) and deoxypyridinoline (dPyr) crosslinks were measured every 6 months to assess bone resorption. Quadriceps isometric strength was measured every 6 months. BMD increased non-significantly at the femoral neck [1.57 (0.8%] and Wards triangle [1.97 (1.4%], and significantly at the greater trochanter 2.21 (0.9)% (P=0.02) in the exercise group. Femoral neck BMD decreased by −1.9(0.8)% (P=0.049) in the control group, which was significantly different from the change in the exercise group (P=0.009). BMD did not change at the Wards triangle or trochanter in the controls. Lumbar spine BMD did not change in either group. Total body BMD did not change in the exercise group, but decreased by −0.79 (0.3)% (P=0.02) in the controls. Follwing 6 months of the exercise classes, Pyr and dPyr crosslinks were significantly reduced [−19.0 (7.2)%;P=0.0019 and −20.0 (7.7)%;P=0.021 respectively]. There was no significant change in crosslinks after 1 year, and no change at any time in the controls. Quadriceps strength changed by 5.4 (3.7)% in the exercise group and by −6.9 (2.5)% (P=0.01) in the control group after 12 months, being significant between groups (P=0.008). This study suggests that high-impact, aerobic exercise in postmenopausal women and men over 50 years old is feasible and effective at maintaining muscle strength and increasing proximal femur BMD but not spine or total body BMD.     

大连地区成年男性身体成分、骨密度、血糖和血脂相关关系

目的:探讨身体成分与骨密度、血糖、血脂的相关性。方法:选择大连地区的汉族成年男性共113名,采用生物电阻抗法分析身体成分,超声骨密度测量仪检测骨密度(BMD),生化分析仪测定血糖(BG)和血脂,计算各项目的平均值及各项目间的相关系数。结果:体脂肪百分数与体质量、体质量指数(BMI)、体脂肪质量和甘油三酯(TG)呈正相关,与高密度脂蛋白胆固醇(HDL-C)呈负相关;BG与体质量、BMI、身体水分(TBW)含量、蛋白质质量、骨骼肌质量、无机盐含量、体脂肪质量、腰臀脂肪比(WHR)和基础代谢率(BMR)呈正相关,与HDL-C和BMD呈负相关;总胆固醇与TG和高、低密度脂蛋白胆固醇呈正相关;TG与年龄、身高、骨骼肌质量、BG和BMD无相关性,与HDL-C呈负相关外,与其他项目均呈正相关;超声波速度、骨折风险指数和骨强度与身高、体质量、BMI、TBW含量、蛋白质质量、无机盐含量、骨骼肌质量、体脂肪质量、WHR、BMR和BG呈正相关。结论:身体成分与BMD、BG、TG和HDL-C具有相关性,与总胆固醇无相关性。     

去卵巢大鼠骨密度变化与骨髓组织血管生成的关系

目的： 探讨去卵巢大鼠骨密度变化与骨髓组织血管生成的关系。方法：30只SD雌性大鼠随机分为去卵巢组（OVX）和假手术组（sham）,分别在4周、8周和12周处死。取左侧股骨测量骨密度(BMD)。右侧远端股骨干骺端松质骨甲醛固定,EDTA-Na2脱钙。常规脱水、石蜡包埋、切片。行苏木素－伊红染色用于观察骨髓组织病理改变,用CD34标记血管内皮细胞观察微血管密度(MVD),采取大鼠腹主动脉血进行血管内皮生长因子(VEGF)测定。结果： 大鼠去卵巢8周后BMD明显低于假手术组, 提示骨质疏松模型建立,此时,骨髓造血组织容量减少,脂肪组织容量增高,与假手术组比较均有显著差异（P<0.01）,骨髓组织MVD与假手术组比略有减少。12周后,上述改变更为明显。同时,骨小梁容量减少,骨髓组织MVD明显减少（P<0.05）,且显示MVD与BMD、造血组织容量和骨小梁容量呈正相关,与脂肪组织容量呈负相关。但血浆VEGF含量测定OVX组与sham组间无明显差异,与骨髓组织各形态指标亦无相关性。结论：去卵巢大鼠在骨量丢失和造血组织容量减少的同时伴有骨髓组织MVD减少, 为骨质疏松症采用促微血管增生治疗提供了实验依据。     

Reduced bone mineral density and low parathyroid hormone levels in patients with the adult form of hypophosphatasia

Summary Hypophosphatasia is a heritable metabolic bone disease with characteristically reduced levels of alkaline phosphatase (ALP) in the blood, liver, kidney and bone. ALP levels are normal in the intestine and placenta. About 300 patients have been reported so far in the literature. Three kindreds with 52 known subjects are described here, whereby 12 subjects could be examined osteologically. Four subjects were patients and had clinical signs of the disease: spontaneous fractures of the metatarsals or femora and low ALP serum levels ranging between 8 and 23 U/1 (normal range 40–170 U/1). Four other members without fractures had reduced ALP levels; they might be carriers of the disease and develop symptoms later in life. The four remaining subjects had normal ALP levels and no signs of the disease. Serum levels of intact parathyroid hormone (iPTH) were found to be in the lower normal range and serum calcium levels in the upper normal range. There was a significant (P<0.05) negative correlation between iPTH and serum calcium levels (r=–0.78). Urinary calcium excretion was increased in 3 subjects with fractures. 25-OH-D₃ levels were increased in 6 of 8 subjects without any treatment. The bone mineral density (BMD) was measured using dual X-ray absorptiometry of the lumbar spine, representing mainly trabecular bone, and single-photon absorptiometry of the forearm, measuring mainly cortical bone. Z-scores of the spinal bone mass ranged between 0.38 and –1.95 SD; Z-scores of the forearm bone mass ranged between 0.53 and –2.47 SD with the lowest values in patients with fractures. There was a significant (P<0.05) correlation between serum ALP levels and forearm BMD (r=0.83). We conclude from these data that patients with the adult form of hypophosphatasia have decreased forearm and subnormal spinal bone mass, as well as reduced serum levels of iPTH.Abbreviations BMD bone mineral density - ALP alkaline phosphatase - iPTH intact parathyroid hormone - 25-OHD₃ 25-hydroxyvitamin D₃ - SD standard deviation - PEA phosphoethanolamine - PPi inorganic pyrophosphate - PLP pyridoxal-5-phosphate - cDNA clonal desoxyribonucleic acid - U/S Ca²⁺ urinary/serum calcium - DXA dual X-ray absorptiometry - DPA dual photon absorptiometry - SPAD bone density of distal forearm measured by single photon absorptiometry - SPAP bone density of proximal forearm measured by single photon absorptiometry     

Effect of natural early menopause on bone mineral density

OBJECTIVES: Early menopause (EM) is included among the risk factors for osteoporosis. Several studies have shown that women with early menopause have lower bone mineral density (BMD) than those with normal expected age of menopause. The aim of our cross-sectional study was to investigate the effects of time of menopause on vertebral bone mass in healthy postmenopausal women and to evaluate if early menopause is a risk factor for lower vertebral BMD. METHOD: We studied 782 who had never received drugs acting on bone mass. The study population was divided into three groups: women with early, normal (NM), and late (LM) menopause. Our study population was further categorized in 5-year age segments between 45 and >75. RESULTS: The three groups examined did not differ for age, age at menarche, body mass index (BMI), and vertebral BMD, while there were significant differences in age at menopause and years since menopause. Our study showed that women with EM presented significantly lower vertebral BMD than NM and LM in 50-54 age segments. Beyond 55 years, EM, NM, and LM women had no differences in lumbar BMD values. CONCLUSIONS: In conclusion, controversial data demonstrated that the absolute amount of bone loss is greater after early menopause than after normal or late menopause, even if a slight effect of early menopause on bone mass cannot be excluded.     

不同年龄女性人群血液中的Dkk-1水平与骨密度相关性的分析研究

目的:探讨不同年龄女性人群血液中的Dickkopf-1(Dkk-1)水平与骨密度之间的相关性。方法:选取2013年3月~2014年6月在我院行体检的100例年龄处于20~80岁之间的女性志愿者,按照不同年龄分为青年组(20~39岁)、中年组(40~59岁)和老年组(60~80岁),从中年女性组中抽取45~55岁25人,分为绝经期女性组和未绝经女性组。采用酶联免疫吸附法测3组志愿者血清Dkk-1的表达水平,采用双能X线骨密度测量仪测定3组志愿者全身矿含量,分析不同年龄女性以及绝经与否女性血清Dkk-1水平的差异及Dkk-1水平与骨密度的关系。结果:随着年龄的增长,人群血清Dkk-1水平相应增高(P0.05),骨密度相应降低(P0.05);3组志愿者中,血清Dkk-1水平与骨密度均呈负相关(P0.05)。45~55岁年龄范围内,绝经组女性血清Dkk-1与未绝经妇女相比,Dkk-1水平与骨密度降低的相关性更为密切(P0.05)。结论:人体随着年龄的增加,血清Dkk-1水平会上升,并出现骨密度下降,有发生骨质疏松症的风险。相同年龄范围妇女中,绝经后妇女Dkk-1水平表达较高,骨密度降低更明显,有更大的发生骨质疏松症危险。Dkk-1表达的增加同时可抑制骨形成和促进骨吸收,有望成为预防和治疗骨质疏松症治疗的一个新靶点。     

睾丸酮对雄性大鼠类固醇性骨质疏松的影响

目的探讨睾丸酮对雄性大鼠类固醇性骨质疏松的影响。方法30只3月龄雄性SD大鼠,随机分成对照组(A组)、泼尼松组(B组)、睾丸酮(C组)。A组灌生理盐水(4mL·kg-1·d-1),B组予醋酸泼尼松灌胃(4mg·kg-1·d-1),C组灌胃给予甲睾酮(0.2mg·kg-1·d-1)+醋酸泼尼松(4mg·kg-1·d-1),共90d。实验结束后,处死全部大鼠取腰椎和胫骨上段进行不脱钙骨包埋切片,应用计算机自动图像分析系统进行骨组织形态计量学分析。结果与泼尼松组比较,胫骨上端松质骨的%Tb.Ar增加了108%(P<0.01),Tb.N增加了96%(P<0.05),Tb.Sp减少60%;BFR/TV增加了172%(P<0.05),Oc.N减少40.7%(P<0.05);腰椎松质骨的%Tb.Ar增加了52.4%(P<0.05),Tb.Th增加了42%(P<0.05),Tb.Sp减少20%(P<0.05),MAR增加26%(P<0.05)。结论睾丸酮可以有效阻止泼尼松所引起的骨骨质丢失,维持正常的骨质结构。     

Influence of number of deliveries and total breast-feeding time on bone mineral density in premenopausal and young postmenopausal women

Objectives

Pregnancy and lactation have been associated with decline in bone mineral density (BMD). It is not clear if there is a full recovery of BMD to baseline. This study sought to determine if pregnancy or breast-feeding or both have a cumulative effect on BMD in premenopausal and early postmenopausal women.

Study design

We performed single-center cohort analysis. Five hundred women aged 35–55 years underwent routine BMD screening from February to July 2011 at a tertiary medical center. Patients were questioned about number of total full-term deliveries and duration of breast-feeding and completed a background questionnaire on menarche and menopause, smoking, dairy product consumption, and weekly physical exercise. Weight and height were measured. Dual-energy X-ray absorptiometry was used to measure spinal, dual femoral neck, and total hip BMD.

Main outcome measures

Associations between background characteristics and BMD values were analyzed.

Results

Sixty percent of the women were premenopausal. Mean number of deliveries was 2.5 and mean duration of breast-feeding was 9.12 months. On univariate analysis, BMD values were negatively correlated with patient age (p = 0.006) and number of births (p = 0.013), and positively correlated with body mass index (p < 0.001). On multiple (adjusted) logistic regression analysis, prolonged breast-feeding duration, but not number of deliveries, was significantly correlated to a low BMD (p = 0.008). An effect was noted only in postmenopausal women. The spine was the most common site of BMD decrease.

Conclusions

Prolonged breast-feeding may have a deleterious long-term effect on BMD and may contribute to increased risk of osteoporosis later in life.     

Site-specific effect of testosterone on bone mineral density in male hypogonadism.

To assess the correlation between the remaining serum testosterone and bone mineral density(BMD), and to determine the effect of exogenous testosterone on BMD in subjects with male hypogonadism, we evaluated the serum testosterone levels and BMDs of the femur neck, Ward''s triangle and the spine(L1-4) in 20 subjects with Klinefelter''s syndrome and 7 with hypogonadotropic hypogonadism before and after testosterone replacement. BMDs of the femur neck, Ward''s triangle and the spine were below the age-matched normal mean at 77.8%(21/20), 74.1%(20/27) and 88.9%(24/27), respectively. There were significant differences in serum testosterone levels and the spinal BMD between the two groups and the BMD of the spine closely correlated with the serum testosterone level (R = 0.63, p < 0.001). Following a mean 11.8 +/- 4.9 months of testosterone replacement, the BMD at all sites increased significantly and the pretreatment difference in spinal BMD between the two groups disappeared. We conclude that, although testosterone may increases the bone density, it has a site-specific effect of maintaining and increasing the bone mass especially at the spine in male hypogonadism.     

Association between depression and bone mineral density in community-dwelling older men and women in Korea

Objectives

Previous research suggested a significant correlation between depression and osteoporosis, but little is known for the elderly Asian population. We investigated an association between depression and bone mineral density (BMD) in the Korean elderly.

Study design

Cross-sectional data analysis of a community-based study, Kangwha Island, South Korea.

Main outcome measures

BMD, measured at the os calcis using a quantitative ultrasound device, was expressed as stiffness index and T-score. Depressive symptoms were evaluated by the Korean version of Beck Depression Inventory (K-BDI). Depression was defined as a K-BDI score of 16 or higher. Participants also completed a questionnaire, including demographic factors, metabolic abnormalities, and health-related lifestyle factors.

Results

A total of 932 local residents (422 men and 510 women) aged 60–80 years completed the questionnaires and baseline BMD evaluation. Men with depression had a significantly lower stiffness index compared to those without depression in an age-adjusted (77.2 ± 5.2 vs. 86.0 ± 1.5, p = 0.002) and a multivariate-adjusted model (78.5 ± 5.2 vs. 85. 9 ± 1.5, p = 0.007). Correspondingly, men with depression had an increased probability of having an osteoporosis (T-score ≤ −2.5) compared to those without depression; the age-adjusted odds ratio was 2.86 (95% CI, 1.36–6.01) and the multivariate-adjusted odds ratio was 2.69 (95% CI, 1.26–5.76). However, no significant association was observed in older women.

Conclusions

Depression was significantly associated with lower BMD in Korean older men, but not in women.     

Meta-analysis of genome-wide linkage studies for bone mineral density

Genome-wide linkage studies have shown several chromosome loci that may harbor genes that regulate bone mineral density (BMD), but results have been inconsistent. A meta-analysis was performed to assess evidence for linkage of BMD across whole genome scan studies. Eleven whole-genome scans of BMD or osteoporosis containing 3,097 families with 12,685 individuals were included in this genome scan meta-analysis (GSMA). For each study, 120 genomic bins of ~30 cM were defined and ranked according to maximum evidence for linkage within each bin. Bin ranks were weighted and summed across all studies. The summed rank for each bin was assessed empirically for significance using permutation methods. A total of seven bins lie above the 95% confidence level (P=0.05) and one bin was above the 99% confidence level (P=0.01) in the GSMA of eleven linkage studies: bins 16.1 (16pter-16p12.3, Psumrnk <0.01), 3.3 (3p22.2-3p14.1), 1.1 (1pter-1p36.22), 18.2 (18p11.23-18q12.2), 6.3 (6p21.1-6q15), 20.1 (20pter-20p12.3), and 18.1 (18pter-18p11.23). GSMA was performed with seven studies with linkage scores of LOD >1–1.85 for sensitivity test, confirming the linkage on chromosome 16p and 3p and revealing evidence of new linkage in bins 10.2 (10p14-10q11.21) and 22.2 (22q12.3-22pter). In conclusion, the meta-analysis of whole-genome linkage studies of BMD has shown chromosome 16pter-16p12.3 to have the greatest evidence of linkage as well as revealing evidence of linkage in chromosomes 1p, 3p, 6, 10, 18, 20p, and 22q across studies. This data may provide a basis with which to carry out targeted linkage and candidate gene studies particularly in these regions.     

Evaluation of methods for prediction of bone mineral density by clinical and biochemical variables in perimenopausal women

Objectives: to predict spinal and femoral bone mineral density (BMD) in perimenopausal women from simple clinical and biochemical variables. Methods: 2016 women 3–24 months past last menstrual bleeding. Mean age 50.1±2.8 years. Age, height, weight, number of full term pregnancies, weekly hours of physical activity, sunbathing habits, use of sun bed, daily intake of calcium and vitamin D, smoking habits, consumption of alcohol, coffee, and tea, history of forearm or femoral neck fractures among the parents, serum osteocalcin (S-OC), serum bone specific isoenzyme of alkaline phosphatase (BSAP), and urine hydroxyproline/creatinine ratio (U-OHP) were used as predictors in three different mathematical models. Lumbar spine (L2–L4) and femoral neck BMD were measured by DEXA. Three mathematical models (multiple regression, logistic regression, and discriminant analysis) were applied. Results: the multiple regression explained 19–21% of the total variation, and the logistic regression and discriminant function had a sensitivity between 53 and 67% with specificity ranging from 67 to 80%. Age, S-OC, serum bone specific alkaline phosphatase, and a maternal history of forearm or femoral neck fractures seemed to be reproducible risk factors for low bone mineral density irrespective of the mathematical model applied. When applied to a separate population, the models performed poorly. Conclusions: Simple clinical and biochemical variables are not useful to predict spinal and femoral BMD in the individual perimenopausal woman.     

Difference in the effects of body composition on bone mineral density between pre- and postmenopausal women

Objective: This study was to investigate whether the effect of lean and fat mass component on bone mineral density (BMD) differs between pre- and postmenopausal women. Materials and methods: Subjects were 360 pre- and 193 postmenopausal Japanese women with right side dominance. Age, height, and years since menopause (YSM, in postmenopausal women) were recorded. Body fat and lean body mass were measured by whole body scanning with dual-energy X-ray absorptiometry (DEXA). BMD of the vertical axis (L2-4 of the lumbar spine, pelvis, bilateral legs, and total body) and horizontal axis (arms) were also measured by DEXA. Results: In premenopausal women, lean body mass was independently correlated with BMD of the left arm (partial correlation COEFFICIENT=0.417), right arm (0.430), L2-4 (0.285), pelvis (0.276), left leg (0.403), right leg (0.412), and total body (0.377) (P<0.001). However, body fat mass was not correlated with several BMD sites except for pelvis BMD (0.187, P<0.01). In postmenopausal women, body fat mass was independently correlated with BMD of the left arm (0.248, P<0.01), L2-4 (0.188, P<0.05), pelvis (0.263, P<0.01), left leg (0.228, P<0.01), right leg (0.319, P<0.001), and total body (0.188, P<0.01)). However, lean body mass was correlated with BMD in only three segmental regions including left arm (0.175), right arm (0.217), and left leg (0.210; P<0.05). Conclusion: Lean body mass is a significant determinant of BMD in premenopausal women, while body fat mass is a significant determinant in postmenopausal women.     

Effects of testosterone on body composition of the aging male

The aging process is accompanied by significant changes in body composition characterized by decreased fat free mass and increased and redistributed fat mass. Muscle loss results from the atrophy of muscle fibers and decreased synthesis of muscle proteins. Increased number of adipocytes and fat accumulation in non-adipose tissue leads to adiposity. These changes can impose functional limitations and increase morbidity. In men, declining testosterone levels that occur with aging can be a contributing factor to these changes. Studies in hypogonadal men have shown that testosterone replacement is effective in increasing muscle mass and strength and decreasing fat mass. The molecular mechanisms of testosterone's influence on muscle and adipose are not fully elucidated. However, testosterone appears to stimulate IGF-1 expression directly and indirectly leading to increased muscle protein synthesis and growth. It may also counter the inhibitory effects of myostatin, cytokines, and glucocorticoids. The predominant effects of testosterone on fat mass are increased lipolysis and decreased adipogenesis. Current evidence suggests that testosterone replacement may be effective in reversing age-dependent body composition changes and associated morbidity. However, hypogonadism must be diagnosed carefully, and therapy should be monitored regularly in order to avoid the adverse effects associated with testosterone supplementation.