不同预处理方式的大块异体骨移植血清骨钙素的变化及意义

目的：观察血清骨钙素（osteocalcin）水平与不同预处理方式的大块异体骨移植愈合的影响及相关性。 方法： 建立犬的骨移植动物模型，15只犬左右前肢随机分成辐照组和无辐照组、加有骨形态发生蛋白(BMP)组和无BMP组、冷冻干燥骨组和低温冷冻骨组。采用双侧尺骨中段切除2 cm骨干和骨膜,再移植2 cm长异体尺骨。术前、术后2周、4周、6周、8周、10周取血检测血清骨钙素。 结果： 在不同处理的异体骨移植中，血清骨钙素水平不同（P<0.05），各个移植时段含量也不同（P<0.05）。 骨形态发生蛋白(BMP)对骨钙素的变化有影响。 结论： ①血清骨钙素是反映异体骨移植中骨代谢的一个特异的、灵敏而简便的生化指标,并对骨移植后骨痂形成程度，具有一定的临床意义。②BMP可使血清骨钙素含量增加，促进成骨。     

Correlation of Undercarboxylated Osteocalcin (ucOC) Concentration and Bone Density with Age in Healthy Korean Women

Uncarboxylated osteocalcin (ucOC) is important in evaluating vitamin K status and it is inversely associated with bone mineral density (BMD). We studied the correlationship between ucOC and BMD in healthy Korean women. This study recruited 337 healthy women between ages 20-70 were recruited. Serum ucOC, calcium, alkaline phosphatase, body mass index (BMI), and BMD were measured and compared. Mean BMI was lowest (20.3±1.9 kg/m²) in the 20 yr old group and highest (24.8±2.6 kg/m²) in the 60 yr old group. Women age 20-70 yr old had ucOC inversely related to BMD independent of other factors that may influence BMD. Serum ucOC concentration and BMD of lumbar spine showed a significant inverse relationship. Serum mean alkaline phosphatase was lowest (122±30 IU/L) in the age 30 group and highest (190.3±55.8 IU/L) in the age 60 group. Serum ucOC was inversely associated with BMI, and positively associated with alkaline phosphatase. Uncarboxylated osteocalcin (ucOC) was inversely associated with spinal BMD in healthy Korean women. Serum mean ucOC was highest in the age 20 group, followed by age 50 group, which may indicate vitamin K insufficiency could be related to high bone turnover in these groups. These results suggest that vitamin K supplement may be considered to help both bone growth and bone loss during these periods.     

Different effects of oral conjugated equine estrogens and transdermal estrogen on undercarboxylated osteocalcin concentration in postmenopausal women

OBJECTIVE: Undercarboxylated osteocalcin (ucOC) is a sensitive marker of vitamin K status, and triglyceride (TG) has been shown to be the main transporter of vitamin K. In the present study, we examined the difference between ucOC concentrations in postmenopausal women receiving hormone therapy (HT) with oral conjugated equine estrogens (CEE) and transdermal estradiol (TE2). We also examined the associations of ucOC concentration with estradiol concentration and TG. DESIGN: Ninety-two postmenopausal women were recruited for this study. Serum concentrations of ucOC, intact osteocalcin, estradiol, and TG were measured before and after 12 months of HT. Forty-six women received oral administration of 0.625 mg of CEE and 2.5 mg of medroxyprogesterone acetate daily, and 46 women received transdermal administration of 50 mug of 17beta-estradiol twice weekly and 2.5 mg of medroxyprogesterone acetate daily. RESULTS: The ucOC concentration in women during HT with oral CEE was significantly (P < 0.01) lower than that in women during HT with TE2. Serum estradiol concentrations during HT with CEE showed a significant inverse correlation with ucOC concentrations and the ratio of ucOC/OC during HT (P < 0.05 and P < 0.01, respectively). In addition, the serum ucOC concentration in women with an increased percentage of change in TG was significantly (P < 0.01) lower than that in women with a decreased percentage of change in TG during HT with oral CEE. CONCLUSION: The effect of HT with TE2 on ucOC concentration in women is weaker than the effect of HT with oral CEE. Suppression of ucOC concentration in postmenopausal women during HT with oral CEE might be associated with the effect of vitamin K through increased TG induced by oral CEE.     

Vitamin K supplement along with vitamin D and calcium reduced serum concentration of undercarboxylated osteocalcin while increasing bone mineral density in Korean postmenopausal women over sixty-years-old

There are inconsistent findings on the effects of vitamin K on bone mineral density (BMD) and undercarboxylated osteocalcin (UcOC). The present intervention study evaluated the effect in subjects over 60-yr-old. The vitamin K group (vitamin K + vitamin D + calcium supplement; 15 mg of vitamin K2 [menatetrenone] three times daily, 400 IU of vitamin D once a day, and 315 mg of calcium twice daily) and the control group (vitamin D + calcium supplement) were randomly assigned. During the six months of treatment, seventy eight women participated (38 in the vitamin K group and 40 in the control group) and 45 women completed the study. The baseline characteristics of study participants did not differ between the vitamin K and the control groups. In a per protocol analysis after 6 months, L3 bone mineral density has increased statistically significantly in the vitamin K group compared to the control group (0.01 ± 0.03 g/cm(2) vs -0.008 ± 0.04 g/cm(2), P = 0.049). UcOC concentration was also significantly decreased in the vitamin K group (-1.6 ± 1.6 ng/dL vs -0.4 ± 1.1 ng/dL, P = 0.008). In conclusion, addition of vitamin K to vitamin D and calcium supplements in the postmenopausal Korean women increase the L3 BMD and reduce the UcOC concentration.     

Relationship between serum undercarboxylated osteocalcin and hyaluronan levels in patients with bilateral knee osteoarthritis

Serum undercarboxylated osteocalcin (s-ucOC) is a marker for vitamin K metabolism (deficiency). The aim of this study was to investigate the serum levels of ucOC in patients with bilateral knee osteoarthritis (K-OA), and the correlation between ucOC and other biomarkers for K-OA. A total of 25 patients (22 women, 3 men, mean age 76.0±7.8, range 54-88 years, mean BMI 24.9±4.7) with a Kellgren-Lawrence grade of 3 or 4 for bilateral knee were enrolled in this study. The levels of s-ucOC and other biomarkers were measured. The levels of s-ucOC (5.66±4.70?ng/ml) as well as other cartilage metabolism markers, were elevated in the patients; however, bone metabolism markers were within the normal ranges. Of interest, there was a significant correlation between s-ucOC and serum hyaluronan (a marker for synovitis) (P<0.05). Our findings suggest that vitamin?K metabolism may be associated with synovitis in patients with K-OA, and s-ucOC could be a biomarker for K-OA.     

Determinants of the decision to perform prophylactic oophorectomy in association with a hysterectomy for a benign condition

Background

The decision to perform an elective bilateral salpingo-oophorectomy (BSO) at the time of a hysterectomy for a benign condition is complex.

Aim

To assess the determinants of the decision to proceed to a prophylactic BSO during a hysterectomy for a benign condition.

Materials and methods

We collected demographic and clinical data, including age, menopausal status and risk of ovarian cancer. Using a regression model we analysed the decision perform a prophylactic BSO in women successively admitted for a hysterectomy for a benign condition, in relation to the collected demographic and clinical data.

Results

Data were collected for 43 women, aged between 37 and 65 years (mean age 48.6 years, SD 6.9), on the day before their hysterectomy. Thirty-six (84%) had a total hysterectomy and 7 (16%) a subtotal hysterectomy; 40 (93%) had a laparoscopic procedure. Prophylactic BSO was significantly associated with age: none of the women aged under 40 years had the procedure, compared with 8% of those aged 41–45 years, 29% of those aged 46–50 years and 83% of those aged 51 years or more (χ² = 23; P < 0.001). Of the postmenopausal women, 67% had a prophylactic BSO, compared with 24% of the premenopausal women (χ² = 6; P < 0.047). In this small series of patients no relationship was found between the decision to perform a BSO and the risk of ovarian cancer. Age was the only significant variable in the regression model (pseudo R² Nagelkerke = 0.6, P < 0.05).

Conclusion

The physician's recommendation to perform an elective BSO at the time of a hysterectomy for a benign condition is strongly influenced by the patients’ age.     

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.     

Effects of 4 mg estradiol valerianate on serum lipids in newly oophorectomized women

The material consisted of 32 patients, 12 of whom were selected for control. All were cases approaching the menopause and had been subject to oophorectomia bilateralis and hysterectomia for myomas. All 20 investigation patients received estradiol valerianate orally 4 mg/day for 6 mth.During the course the serum estradiol level increased 5–6-fold from the postmenopausal levels.No significant changes occurred in the serum triglycerides and total cholesterol, whereas in the control group the triglycerides decreased.The proportional concentration of β-lipoproteins decreased. There was also a slight decrease in the pre-β-lipoproteins. The proportional concentration of β-lipoproteins increased, as also serum high density lipoprotein (HDL) cholesterol.In the liver enzymes no changes occurred. Blood pressure increased in one patient. There were no other complications.     

Usefulness of a novel monoclonal antibody against human osteocalcin in immunohistochemical diagnosis

Summary A novel monoclonal antibody against human osteocalcin, recently established in our laboratory, was shown by immunoblotting and immunohistochemistry to react specifically with human osteoblasts. In the present study, the antibody was applied to the immunohistochemical diagnosis of human bone tumours, especially osteoblastic tumours. The antibody reacted with all 27 osteosarcomas. No positive reaction was found either in chondrosarcoma, giant cell tumours of bone, soft tissue tumours or epithelial tumours. A positive reaction was found preferentially in the cytoplasm of most of the osteosarcoma cells, but not in the extracellular matrix. Since the antibody reacted with formalin-fixed and paraffin-embedded tissues, it will be a useful tool for routine immunohistochemical diagnosis of osteoblastic lesions.     

Interest of biochemical markers of bone turnover for long-term prediction of new vertebral fracture in postmenopausal osteoporotic women

Objective: To analyse the interest of baseline levels and short-term (3-months) changes in serum osteocalcin (BGP), serum bone-specific alkaline phosphatase (BALP) and urinary C-telopeptide of type I collagen/creatinine ratio (U-CTX) to predict 3-years changes in bone mineral density (BMD) and spinal deformity index (SDI) in postmenopausal osteoporotic women. Methods: Data were derived from a cohort of 603 osteoporotic women corresponding to the placebo arm of a 3-years prospective, double-blind study. Results: Baseline values of BALP, BGP and U-CTX were negatively and significantly correlated with baseline spinal BMD. Significant correlations were also observed between the changes in BMD observed after 36 months at the spine and baseline BALP (r=0.20, P=0.0001), BGP (r=0.09, P=0.05) and U-CTX (r=−0.11, P=0.02). At 3 years, 71 women (15.9%) showed an increase in their SDI, corresponding to the occurrence of at least one new vertebral deformity. Baseline values of the four bone turnover markers (BTM) were not significantly related to the occurrence of new vertebral deformities. However, when considering the changes in the BTM observed after 3-months of follow-up, BGP (P=0.003) and U-CTX (P=0.047) were identified as significant predictors of an increase of SDI. The associated odds ratios (95% confidence interval (CI)) were 10.922 (2.218–53.78) for unit changes of log BGP and 1.369 (1.003–1.867) for unit changes of log U-CTX. The relative risk (RR) (IC 95%) of having a new vertebral fracture over 36 months was 0.31 (0.15–0.65) when being in the lowest quartile of 3-months changes in BGP as compared with the highest. Conclusion: We conclude that two sequential measurements of BGP and U-CTX performed at 3-months intervals could be of interest to identify postmenopausal osteoporotic women with the highest risk to present new vertebral deformities.     

Undercarboxylated osteocalcin concentration in postmenopausal women receiving hormone therapy daily and on alternate days

OBJECTIVE: Undercarboxylated osteocalcin (ucOC) is a sensitive marker of vitamin K status. The authors examined the difference in serum ucOC concentrations in postmenopausal women receiving hormone therapy (HT) daily and on alternate days, and assessed the association between ucOC and triglyceride concentrations, which are related to the transport of vitamin K. DESIGN: Seventy-three postmenopausal women were recruited for this study. Thirty-seven women received 0.625 mg of conjugated equine estrogens (CEE) and 2.5 mg of medroxyprogesterone acetate (MPA) daily, and 36 women received 0.625 mg of CEE and 2.5 mg of MPA on alternate days. The concentrations of serum ucOC, bone turnover markers, lipid profiles, and hormones were measured before and after 12 months of HT. RESULTS: The ucOC concentration in women taking HT daily was significantly (P < 0.01) lower than that in women taking HT on alternate days. Serum ucOC concentrations during HT showed a significant (P < 0.01) inverse correlation with estradiol concentrations during HT. Serum estradiol concentrations during HT showed a significant (P < 0.01) positive correlation with triglyceride concentrations during HT. Furthermore, ucOC concentrations during HT showed a significant (P < 0.05) inverse correlation with triglyceride concentrations in women receiving HT. CONCLUSIONS: The effect of HT on alternate days on ucOC concentration was weaker than the effect of HT daily. In addition, ucOC concentration after 12 months of HT daily might be decreased due to the conversion of ucOC to carboxylated OC by the effect of vitamin K through increased triglyceride levels induced by oral CEE.     

Gingival crevicular fluid calprotectin, osteocalcin and cross-linked N-terminal telopeptid levels in health and different periodontal diseases

Aim: The aim of the present study was to investigate gingival crevicular fluid (GCF) calprotectin, osteocalcin and cross-linked N-terminal telopeptide (NTx) levels in health along with different periodontal diseases. Material and methods: Twenty chronic periodontitis (CP), 20 generalized aggressive periodontitis (G-AgP), 20 gingivitis and 20 healthy subjects were included. Probing depth, clinical attachment level, plaque index and papillary bleeding index was recorded. GCF calprotectin, osteocalcin and NTx levels were analyzed by enzyme-linked immunosorbent assay (ELISA). Results: CP, G-AgP and gingivitis groups had higher GCF calprotectin total amount compared to healthy subjects (p < 0.008). CP and G-AgP groups had similar, but higher levels compared to gingivitis groups (p < 0.008). CP and G-AgP groups had lower GCF osteocalcin total amount compared to gingivitis and healthy groups (p < 0.008). CP group had higher GCF NTx but lower osteocalcin total amount and osteocalcin/NTx ratio than the G-AgP group (p < 0.008) Conclusions: Our results suggest that elevated GCF calprotectin levels play a role as a reliable inflammatory marker in the pathogenesis of periodontal disease. Fluctuating GCF levels of osteocalcin and NTx might point out to the abnormal bone turnover in periodontitis. Our data document for the first time the role of NTx in the pathogenesis of different periodontal diseases.     

甲状腺机能亢进症患者血清骨钙素变化的研究

为探讨甲状腺机能亢进症时 ,高甲状腺激素水平对血清骨钙素的影响 ,本文对 87例甲状腺机能亢进患者及 5 2名健康志愿者采用放射免疫法测定了血清骨钙素 (OC)、FT3、FT4 和TSH。结果显示 :健康志愿者血清骨钙素水平随着年龄的增高而逐渐降低 ;男女性别间经统计学处理无显著性差异 (P >0 .0 5 )。各年龄组甲亢患者治疗前OC浓度明显升高 (P <0 .0 0 1) ,经抗甲状腺药物治疗甲亢症状缓解后 ,血清OC浓度也降至正常 ;相关统计分析表明 ,甲亢治疗前、后血清OC与FT3、FT4 之间呈明显的正相关 (FT3:r =0 .84- 0 .2 7　P <0 .0 1;FT4 :r=0 .5 8- 0 .2 9　P <0 .0 1) ;与TSH无相关性。结论 :甲状腺激素可能直接参与加速骨转换过程 ,并以增加骨吸收过程为显著 ,导致骨量丢失 ;提示血清OC可以作为甲亢所致骨代谢改变的诊断及其疗效观察的敏感指标之一。     

Relationship of osteocalcin and matrix Gla protein gene polymorphisms to serum osteocalcin levels and bone mineral density in postmenopausal Korean women

OBJECTIVE: To investigate the relationship of osteocalcin and matrix Gla protein (MGP) gene polymorphisms to serum osteocalcin levels, and bone mineral density (BMD) in postmenopausal Korean women. DESIGN: The osteocalcin gene Hind III and MGP gene cytosine-adenine polymorphisms were analyzed in 267 postmenopausal Korean women. Serum osteocalcin, bone alkaline phosphatase, C-telopeptide of type I collagen, and BMD at the lumbar spine and femoral neck were measured. RESULTS: No significant differences in BMD of the lumbar spine and femoral neck were observed across MGP genotypes, whereas a significant lower BMD at the lumbar spine (but not at the femoral neck) was observed in women with the (h) allele (lower case 'h' signifies the presence of the Hind III site) in a dose-response manner. Serum osteocalcin levels among bone turnover markers studied were significantly higher in women without the 210-bp MGP (cytosine-adenine) allele, or with the osteocalcin hh genotype. CONCLUSIONS: The osteocalcin gene Hind III polymorphism is a genetic factor that is associated with BMD of the lumbar spine in Korean women, and Gla gene polymorphisms are associated with higher osteocalcin levels.     

Serum osteocalcin levels in primary hyperparathyroidism

Summary The serum levels of osteocalcin, a 49-amino-acid bone-matrix protein, have been found to be a specific biochemical parameter of bone formation. The aim of our study was to compare the sensitivity of serum osteocalcin levels with that of alkaline phosphatase in the evaluation of patients with primary hyperparathyroidism. In 40 patients with biochemically and histologically confirmed primary hyperparathyroidism, the serum levels of osteocalcin, intact parathyroid hormone, alkaline phosphatase, calcium, phosphorus, and creatinine were determined preoperatively. The serum levels of osteocalcin were elevated in 22 patients (55%), whereas the serum levels of alkaline phosphatase were increased in 18 patients (45%). In 10 patients (25%) the serum levels of osteocalcin, but not those of alkaline phosphatase, were increased, whereas in six patients the activity of alkaline phosphatase was high, but the serum osteocalcin levels were normal. When the biochemical data of the patients with increased serum osteocalcin levels were compared with those of the patients with serum osteocalcin levels within the normal range, the serum levels of intact parathyroid hormone and alkaline phosphatase were significantly increased in the group of patients with elevated serum osteocalcin levels. Our data indicate that serum osteocalcin levels might be a clinically useful additional parameter in the evaluation of patients with primary hyperparathyroidism.     

甲状腺疾病与血清骨钙素的关系及其临床意义

观察各种甲状腺疾病治疗前、后血清骨钙素的变化，以探讨甲状腺功能异常与骨代谢的关系。本文对236例甲状腺疾病患者及52名健康志愿者为对照组，采用酶放大化学发光法测定了血清骨钙素(BGP)、FT3、FT4、TSH和人甲状腺球蛋白(HTG)。结果显示：正常人血清骨钙素水平随着年龄的增高而逐渐降低；甲亢患者治疗前。BGP浓度明显升高；甲减患者治疗前BGP浓度明显低于正常，经短期甲状腺紊替代治疗后，BGP浓度明显高于正常；治疗前的亚甲炎患者BGP浓度明显高于对照组，用糖皮质激素治疗后，BGP浓度反低于正常水平。相关统计表明，治疗前、后的甲亢、甲减和亚甲炎患者BGP与FT3、FT4之间呈明显的正相关；甲减患者BGP与TSH呈负相关。实验结果显示甲状腺激素可能直接参与加速骨转换过程，并以增加骨吸收过程为显著；糖皮质激素可使骨转换率减低，骨的形成降低，最终都可能导致骨矿丢失。     

MBL serum concentration in women with HPV presenting CIN III lesions

Purpose

This study proposes to assess MBL serum concentrations in HPV positive women that developed high risk preinvasive lesions, CIN III.

Materials and methods

A total of 90 consecutive women (mean age 32.2 years, range 18–45 years) with CIN III lesions confirmed by cone biopsy were enrolled as cases at the gynecology cancer department of the Erasto Gaertner Hospital, a center of reference for cancer treatment in Southern Brazil. All the patients were HPV positive. In addition, 81 healthy women, voluntary blood donors, were enrolled as healthy control subjects (mean age 33.3 years, range 14–71 years) with no evidence of HPV infection, tested by hybrid capture, or CIN lesions, from the same geographic area.

Results

The median concentration of MBL in the cases was 912 ng/ml (IQR: 100–5820 ng/ml) and in the controls was 1207.3 ng/ml (IQR 100–4320.6 ng/ml). No statistically significant difference was observed between cases and controls.

Conclusion

This study reports data on MBL serum concentrations in HPV infected women for the first time. The analysis of our findings did not show a statistically significant difference between MBL serum concentrations in HPV women that developed CIN III lesions and healthy controls.     

Markers of collagen synthesis and degradation in urogenital tissue and serum from women with and without uterovaginal prolapse

Diverging results have been published concerning collagen metabolism in uterovaginal prolapse (UP). We have investigated collagen turnover in urogenital tissue in urologically healthy women with (UP patients) and without UP or any history of UP (controls). Markers of collagen turnover, carboxy-terminal propeptide of type I procollagen (PICP), amino-terminal propeptide of procollagen III (PIIINP) and carboxy-terminal telopeptide of type I collagen (ICTP) were assayed in urogenital tissue homogenates and serum. Tissue and serum concentrations of collagen turnover markers were related to UP and to menopausal/estrogen status. UP patients were significantly older than the controls. UP patients had significantly higher tissue PICP and PIIINP and significantly lower tissue ICTP levels than the controls, but the difference in ICTP disappeared after matching for menopausal/estrogen status and age. There were no associations between tissue collagen turnover markers on the one hand and menopausal/estrogen status or age on the other. The higher tissue concentrations of PICP and especially PIIINP in tissue from women with UP compared to controls, suggest an increased collagen breakdown in UP. This pattern differs from that in stress urinary incontinent women without UP, where tissue levels of collagen turnover markers are low, indicating reduced collagen breakdown.     

Factors associated with premature ovarian failure, early menopause and earlier onset of menopause in Japanese women

Objective

The purpose of this study is to clarify the median age at natural menopause and the proportions of women with premature ovarian failure (POF) and early menopause (EM) by using Kaplan–Meier cumulative estimates and differences in reproductive and lifestyle factors associated with POF, EM and median age at menopause in a large population of Japanese women.

Subjects and methods

This study is a cross-sectional analysis of the Japan Nurses’ Health Study (JNHS). We analyzed data for 24,152 pre- and postmenopausal women who were 40 years or older at the JNHS baseline survey.

Results

The overall estimated median age at natural menopause was 52.1 years, and the proportions of women with POF and EM were 0.28% and 1.67%, respectively. Older generation, cigarette smoking, low body mass index, regular menstruation cycles at 18–22 years of age, nulliparity and unilateral oophorectomy were associated with earlier onset of natural menopause.Only unilateral oophorectomy was associated with increased risk of POF, and nulliparity and unilateral oophorectomy were associated with increased risk of EM.

Conclusion

Unilateral oophorectomy is a common factor associated with earlier onset of menopause, EM and POF, although other reproductive and lifestyle factors are not associated with POF or EM.     

Bilateral asymmetry in bone weight at various skeletal sites of the rat

Background: Morphological and funtional asymmery in the limbs has generally been regarded as a human characteristic that is of genetic or of the geneic and environmental origin. The aim of this study was to determine the presence of lateral dominance in bone weight of the forelimb of the rat. Methods: Wistar rats (77) were used, 45 Controls and 32 experimental animals, implanted with a steel weight subcutaneously under the light forelimb. Bones exmined for bilateral asymmetry in bone weight were the mandibula, the bones of fore- and hindlimbs, calcaneus, and talus of the tarsus. The Weight of eact dr done was measured to the nearest milligram. Results: Significant bilateral asymmetry in the forelimb was evident in male and female rats, with the left sidehaving more bone mass than the right. Bilaterial difference were more pronounced in the females than the male rats. Greater asymmetr was evident in the experimental group compared to the control rats. Conclusions: These findings demonstrate that asymmetry is present not only in humans, but also in lower animals such as rats. Greater asymmery in the experiemntal rat group is indicative of the influence of environmental factors or physical stress on asymmetry. We conclude that genetics might control the development of asymmetr, but physical stress may alter the functional expression of the asymmetry. © 1995 Wiley-Liss, Inc.