Who influences employees’ dark side: A multi-foci meta-analysis of counterproductive workplace behaviors

We adopt a multi-foci perspective to provide a theory-driven quantitative review of employee counterproductive workplace behaviors (CWBs) by meta-analyzing the relationships between CWB and four groups of antecedents. Specifically, CWB antecedents stemming from four sources—supervisors, organization, coworkers, and private life—were included to investigate differences in their relationships with employee CWB. Based on the Conservation of Resources Theory, we argue that favorable and unfavorable correlates relate to employee CWB to different degrees. The meta-analysis included 181 field studies with 223 independent samples. Results indicated that unfavorable antecedents correlate more strongly with CWB than favorable antecedents. We also found that supervisor- and organization-related antecedents have stronger relationships with CWB than those from the two other groups. Implications include a deeper understanding of which situational factors relate the most—or least—to CWB which can help better address CWB in the workplace.

A resource-based perspective on work–family conflict: meta-analytical findings

Purpose

The purpose of this paper is to provide an updated and theory-driven meta-analysis of work–family conflict (WFC). The authors quantitatively review the relationships between WFC and three pairs of antecedents and several consequences.

Design/methodology/approach

A meta-analysis was conducted to investigate the research model. Specifically, the authors adopt a resource-based perspective (i.e. conservation of resources (COR) theory) to investigate the relationships between three pairs of antecedents (demand/control, autonomy/hours spent at both work and family domains and role overload/flexibility) and WFC. While COR theory argues that resource loss perceptions would generate much more influential impact on individuals comparing to that of resource gain, both favourable and unfavourable antecedents, representing resource gain and resource loss, respectively, are incorporated in each pair of antecedents. This inclusion of contrary antecedents allows the authors to investigate the comparison of the relationships between the favourable antecedents – WFC relationships and the unfavourable factors – WFC relationships. In addition, the authors analyse how and to what extent WFC influences employees’ attitudes (i.e. commitment), behaviours (i.e. performance) towards both work and family, and their career consequences.

Findings

The meta-analytical findings generally support the hypotheses. Work and family demands are found positively related to WFC, while having a control at either work or family would be negatively related to WFC. Perceiving a high level of autonomy at work is negatively related to WFC, and hours spend at work has a positive relation with WFC. Role overload at both work and family are associated with WFC, while having flexibility from work schedule would be negatively related to WFC. In addition, WFC is negatively related to employee career development outcomes.

Originality/value

First, the authors adopt a resource-based view to organise both favourable and unfavourable antecedents of WFC. Second, this paper aims at extending the investigation on WFC consequences to performance at both work and family, commitment to both work and family, and employee career outcomes, because all of them are critical consequences but not fully explored in previous meta-analyses. Third, this paper has incorporated newly explored correlates of WFC (e.g. employee career development-related outcomes) and quantitatively reviewed their relationships with WFC.

Data from a pre-publication independent replication initiative examining ten moral judgement effects

We present the data from a crowdsourced project seeking to replicate findings in independent laboratories before (rather than after) they are published. In this Pre-Publication Independent Replication (PPIR) initiative, 25 research groups attempted to replicate 10 moral judgment effects from a single laboratory's research pipeline of unpublished findings. The 10 effects were investigated using online/lab surveys containing psychological manipulations (vignettes) followed by questionnaires. Results revealed a mix of reliable, unreliable, and culturally moderated findings. Unlike any previous replication project, this dataset includes the data from not only the replications but also from the original studies, creating a unique corpus that researchers can use to better understand reproducibility and irreproducibility in science.

Alendronate sodium/vitamin D3 combination tablet versus calcitriol for osteoporosis in Chinese postmenopausal women: a 6-month, randomized, open-label, active-comparator-controlled study with a 6-month extension

This study compares efficacy of ALN/D5600 versus that of calcitriol in osteoporotic Chinese postmenopausal women. ALN/D5600 produced greater bone mineral density (BMD) increases, greater bone turnover marker decreases, and less vitamin D insufficiency. This study provided detailed clinical information regarding ALN/D5600 treatment versus calcitriol 0.25 μg/day. The study did not evaluate fracture risk.

INTRODUCTION

The aim of this study is to investigate efficacy of alendronate 70 mg/vitamin D3 5600 IU combination tablets (ALN/D5600) versus calcitriol in osteoporotic Chinese postmenopausal women.

METHODS

This study is a 6-month, randomized, open-label, active-comparator study with 6-month extension (clinicaltrials.gov number NCT01350934) in postmenopausal women aged >55 years with osteoporosis (low bone mineral density (BMD) with/without prior fragility fracture). Patients were randomized to ALN/D5600 once weekly or calcitriol 0.25 μg daily. The primary efficacy end point of the base study was percent change from baseline in lumbar spine BMD (month 6). Hypercalcemia and hypercalciuria were safety events of special interest.

RESULTS

A total of 219 patients (ALN/D5600 n = 111, calcitriol n = 108) were randomized. Baseline characteristics were similar, 30.3 % baseline 25-hydroxyvitamin D (25(OH)D) ≤15 ng/mL. At months 6 and 12, changes in lumbar spine BMD from baseline were 3.5 versus 1.6 % and 5.2 versus 2.3 % for ALN/D5600 versus calcitriol (between-group differences p < 0.001), respectively. Between-group differences for ALN/D5600 versus calcitriol were significant (p < 0.001) at months 6 and 12 for change from baseline in procollagen type 1 N-terminal propeptide (-59.1 versus -16.8 %, -68.1 versus -17.0 %) and serum C-telopeptides (-79.2 versus -27.2 %, -76.2 versus -24.2 %). Drug-related adverse events (AEs) and discontinuations due to drug-related AEs occurred in 15 (14.0 %) versus 8 (7.4 %) patients and 3 (2.8 %) versus 0 patients in the ALN/D5600 and calcitriol group, respectively. Hypercalciuria 12-month incidence (24-h urine Ca >300 mg) was 8.4 (ALN/D5600) versus 13.9 % (calcitriol) (p > 0.05). One patient (calcitriol) had hypercalcemia.

CONCLUSIONS

ALN/D5600 produced greater increases in lumbar spine BMD and greater decreases in bone turnover markers versus calcitriol in osteoporotic Chinese women. It is not known whether the greater increase in BMD results in fewer fractures. ALN/D5600 was generally well tolerated in Chinese patients.

Relationships between serum omentin-1, body fat mass and bone mineral density in healthy Chinese male adults in Changsha area

PURPOSE

The present study is firstly designed to identify the relationship between serum omentin-1 concentration, body fat mass and bone mineral density in healthy Chinese male adults in Changsha city.

METHODS

A total of 219 (20-80 years old) healthy subjects were enrolled in this cross-sectional study. Serum omentin-1, adiponectin, leptin, resistin and bone turn over biochemical markers were measured with enzyme-linked immunosorbent assay. Bone mineral density (BMD) and fat body composition were determined using dual-energy-X-ray absorptiometry.

RESULTS

Serum omentin-1 levels in the overweight subjects were significantly lower than those of the subjects with normal weight (p < 0.05). Omentin-1 was negatively correlated with weight (r = -0.418), body mass index (BMI, r = -0.419), waist circumference (r = -0.402), waist-to-hip ratio (WHR, r = -0.355), fat body mass (FBM, r = -0.430), fat % (r = -0.408), trunk fat (-0.431). However, after controlling for age, BMI and FBM, no significant correlation was noticed between omentin-1 and BMD at different skeletal sites. Pearson's correlation coefficients and partial correlation coefficients after adjustment showed no significant correlations between omentin-1 and bone turn over biochemical markers, including bone-specific alkaline phosphatase and bone cross-linked N-terminal telopeptides of type I collagen. Multiple line stepwise regression analysis revealed that FBM, WHR, adiponectin were important variables affecting omentin-1. Moreover, lean tissue mass was the most important factor affecting BMD and explained 10.5-14.7 % of the variance. Omentin-1, leptin and resistin were not the predictors of BMD.

CONCLUSIONS

Serum omentin-1 was negatively correlated with FBM and BMI in healthy Chinese male adults, It was not significantly correlated with bone turnover biochemical markers. Omentin-1 may exert ambiguous effects on BMD, which maybe caused by the complex interactions among adipokines, hormonal activity, and body composition and bone metabolism.

Age-related bone mineral density, osteoporosis rate and risk of vertebral fracture in mainland Chinese women with type 2 diabetes mellitus

Few data are available regarding bone mineral density (BMD) and the risk of vertebral fracture among mainland Chinese women with type 2 diabetes mellitus (T2DM). A decrease in the bone projective area (BPA) can be an indirect marker reflecting compressed vertebral fracture. We investigated age-related BMD, BPA, and the prevalence of osteoporosis in women with T2DM in mainland China. BMD and BPA of the posteroanterior lumbar spine (L1-L4) and hip were measured by dual-energy X-ray absorptiometry in 1253 women with T2DM and 1194 control subjects without diabetes aged 40-80 yr. BMD of the lumbar spine and hip decreased with age. BMD of the lumbar spine was higher in T2DM than controls (p<0.05-0.001), as was BPA at some vertebral bodies (p<0.05-0.001), whereas no significant intergroup differences in BPA were observed at the hip. The prevalence of osteoporosis in the women with T2DM increased with age: 0-2.58% at age 40-49 yr, 6.94-28.4% at age 50-59 yr, 32.7-76.7% at age 70-80 yr, with the range reflecting differences between skeletal sites. In subjects over 60 yr, the rates of osteoporosis at posteroanterior spine were significantly lower in T2DM patients than in controls (p<0.05-0.001). In conclusion, women with T2DM had higher BMD and lower risk of osteoporosis. Higher BPA of the vertebrae indicated that women with T2DM in mainland China would have a lower risk of vertebral fracture than non-diabetic women.

Regionally specific compensation for bone loss in the tibial trabeculae of estrogen-deficient rats

BACKGROUND

Bone mineral density (BMD) and microstructural variations have been extensively investigated in recent years; however, the compensation for bone loss between different regions is still unclear.

PURPOSE

To fully characterize regional variations in bone mineral density (BMD) as well as the microstructure and dynamic changes of rat tibial trabeculae that occur with bone loss associated with estrogen deficiency.

MATERIAL AND METHODS

Female Sprague-Dawley rats were ovariectomized (OVX), sham-operated (sham), or left unoperated (baseline control). The left tibiae were harvested at baseline, and at postoperative weeks 3 and 15. High-resolution micro-computed tomography (microCT) was used to identify the densitometric and microstructural properties of trabeculae in the proximal ends of the rat tibia, specifically the epiphysis and metaphysis.

RESULTS

Volumetric BMDs at the organ (organ BMD) and tissue (tissue BMD) levels were significantly higher for trabeculae at the epiphysis than metaphysis. Moreover, trabeculae at the epiphysis were thicker, and fewer in number and connectivity than those at the metaphysis, which were more rod like. Trabeculae at the metaphysis were more susceptible to bone loss induced by estrogen deprivation than at the epiphysis, and the regions varied greatly in their adaptation to this loss. At the metaphysis, trabecular tissue BMD and thickness were unexpectedly higher at postoperative week 15 than week 3 or baseline. In contrast, at the epiphysis, tissue BMD did not change with time, but trabecular thickness significantly increased at week 15 compared to baseline and was also greater in OVX compared to sham rats.

CONCLUSION

Metaphyseal and epiphyseal trabeculae show regionally specific variations in BMD and microstructure. The former are more susceptible to bone loss induced by estrogen deficiency and would be strengthened by either hypertrophy or hypermineralization, while epiphyseal trabeculae are mainly strengthened by thickening.

Ascorbic acid inhibits osteoclastogenesis of RAW264.7 cells induced by receptor activated nuclear factor kappaB ligand (RANKL) in vitro

Ascorbic acid (AA) plays a key role in the regulation of differentiation and activation of osteoclast (OCL). It was reported that AA might induce the formation of OCL in cocultures of mouse bone marrow cells and ST2 cells, but it is not clear whether AA has a direct impact on the OCL precursors. The purpose of this study was to examine the effect of AA on the differentiation of OCL precursor RAW264.7 cells, cultured with receptor-activated nuclear factor kappaB ligand (RANKL). The results showed that AA remarkably inhibited the cell proliferation at a higher concentration and RANKL alone is sufficient for osteoclastogenesis. The expression of carbonic anhydrase (CAII) mRNA and protein, the number of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells (MNCs), and the percentage area of resorption lacunae induced by RANKL were decreased when AA was added to the cultures. The results demonstrate that AA inhibits RANKL-induced differentiation of OCL precursor cells into mature OCL and reduces the formation of bone resorption pits in vitro.

Membrane-type matrix metalloproteinase-1 (MT1-MMP) is down-regulated in estrogen-deficient rat osteoblast in vivo

Our previous study showed that estrogen stimulates membrane-type matrix metalloproteinases-1 (MT1-MMP) production in osteoblastic cells culture, but has no effect on MMP-2 and TIMP-2 synthesis. Osteoblast-derived MT1-MMP have been recently implied to play a role in bone metabolism by degrading tumor necrosis factor-alpha (TNF-alpha), resolving extracellular matrix and activating proMMP-2, which requires the process of activation mediated by MT1-MMP/tissue inhibitor of metalloproteinase (TIMP-2) complex on the cell surface. To investigate the mechanism of bone loss following estrogen deficiency, we examined the effects of estrogen on osteoblast synthesis of MT1-MMP, MMP-2 and TIMP-2. In situ hybridization and immunohistochemistry of rat bone samples were used to document the synthesis of MT1-MMP, MMP-2, and TIMP-2 mRNA and protein. Osteoblasts from distal femoral head showed an increase in the pattern of MT1-MMP mRNA and protein production in sham-operated controls and 17beta-estradiol (E2)-treated rats, compared with the ovariectomized group; the synthesis of MMP-2 and TIMP-2 mRNA and protein was unaffected. Our data show a down-regulation of MT1-MMP synthesis by osteoblast in vivo following estrogen withdrawal, and treatment with E2 resulted in induced MT1-MMP expression in vivo. There is evidence suggesting a role for MT1-MMP in the process of bone loss during the pathogenesis of osteoporosis.

Recombinant matrix metalloproteinase-14 catalytic domain induces apoptosis in human osteoblastic SaOS-2 cells

Our study previously showed that estrogen and progesterone stimulated the production of matrix metalloproteinase-14 [MMP-14, or also named membrane type matrix metalloproteinses-1 (MT1-MMP)] in osteoblastic cells. MMP-14 was implied to regulate the function of osteoblasts by degrading bone matrix or growth factors, but the mechanism is unclear. Since MMP-14 plays a role primarily through the catalytic domain, and truncated MMP-14 containing the catalytic domain and lacking transmembrane domain can be secreted into medium by cultured cells, our present study was performed to observe the direct effects of recombinant MMP-14 catalytic domain on cultured human osteoblastic osteogenic sarcoma (SaOS)-2 cells. Our data showed that recombinant MMP-14 catalytic domain activated proMMP-2 secreted into media by SaOS-2 cells, and this process was blocked by ethylenediamine tetraacetic acid (EDTA) treatment. Recombinant MMP-14 catalytic domain inhibited the adhesion of SaOS-2 cells to immobilized type I collagen or fibronectin in a dose-dependent manner, and these effects on SaOS-2 cells were abolished by EDTA. Recombinant MMP-14 catalytic domain induced SaOS-2 cells apoptosis in a dose-dependent manner, and apoptosis-inducing activity of MMP-14 catalytic domain was blocked if it was treated with EDTA. In conclusion, we revealed that recombinant MMP-14 catalytic domain induced SaOS-2 cells apoptosis. We also indirectly showed the activity of MMP-14 catalytic domain to degrade extracellular matrix (ECM) in cultures of SaOS-2 cells through Gelatin Zymograms and adhesion assay. This suggests that since adhesion of cells to ECM serves as a survival mechanism in osteoblasts, the catalytic activity of recombinant MMP-14 catalytic domain on matrix proteins contributes to its apoptosis-inducing activity.

A comparison study of the reference curves of bone mineral density at different skeletal sites in native Chinese, Japanese, and American Caucasian women

To understand the differences among reference curves for bone mineral density (BMD) for Chinese, Japanese, and American Caucasian women, we measured the BMD at the anteroposterior (AP) lumbar spine (L1-L4), lateral lumbar spine (L2-L4), hip (including the femoral neck, trochanter, intertrochanter, Ward's triangle, and total hip), and ultradistal forearm by the dual-energy X-ray absorptiometry (DXA) in a total of 2728 healthy Chinese women, aged 5-96 years. Documented BMD data for Japanese women and device manufacturer's BMD new reference databases (including the NHANES III dataset) for American Caucasian women were also used in this study. The cubic regression model was found to fit best in analyzing the age-associated variations of BMD at various sites in Chinese women, i.e., the equations had the largest coefficient of determination (R2). At the AP/Lat spine, trochanter, intertrochanter, and Ward's triangle, BMD reference curves for Chinese women were lower than those for Japanese or Caucasian women, while at the femoral neck, total hip, and ultradistal forearm, the reference curves for Chinese women were higher than those for Japanese women, with overlaps and crossing of the curves for some age spans in comparing the Chinese and Caucasian women. There were significant differences in the peak BMD (PBMD) at various sites among the Chinese, Japanese, and Caucasian women (P = 0.000). The PBMDs for Chinese women at the lumbar spine and various sites of the hip were 5.7% +/- 2.1% (mean +/- SD, range, 2.7-7.9%) lower than those for Japanese women and 5.1% +/- 2.7% (range, 0.5-7.2%) lower than those for Caucasian women; however, the PBMDs for Chinese women were 26.2% higher than those for Japanese women and 10% higher than those for Caucasian women at the ultradistal forearm. After the PBMD, average T-scores of Chinese women for losses at the AP lumbar spine with increasing age were nearly identical to those for Japanese women, but both were greater than those for Caucasian women. The average T-scores for BMD loss at various sites in Chinese women were higher than those for both Japanese and Caucasian women except at the femoral neck, where the T-scores of Chinese women were exceeded by those of both Japanese and Caucasian women. Estimated from the T-score curve of BMD loss, the age of osteoporosis occurrence at the femoral neck in Chinese women was about 10 years later than that in Japanese or Caucasian women; at the AP spine, Chinese women were similar to Japanese women; at the other sites, the age for occurrence of osteoporosis in Chinese women was about 5-15 years earlier than that in either Japanese or Caucasian women. There are differences in prevalence or odds ratio (OR) of osteoporosis at the same skeletal region for Chinese, Japanese, and Caucasian women aged > or = 50 years or at different skeletal regions in women of the same race. The prevalences of osteoporosis at various regions of the hip in Chinese women are 10.1-19.8% and ORs are 22.0-32.3, of which prevalence at the femoral neck is the lowest (10.1%); the prevalences of osteoporosis in Japanese women are 11.6-16.8% and ORs are 21.1-26.3, of which prevalence at the femoral neck is the lowest (11.6%); and the prevalences of osteoporosis in Caucasian women are 13.0-20.0% and ORs are 19.4-48.9, of which prevalence at the femoral neck is the highest (20%). In conclusion, racial differences in BMD reference curves, prevalences, and risks of osteoporosis at various skeletal sites exist among native Chinese, Japanese, and American Caucasian women.

Comparison of the effects of 17beta-E2 and progesterone on the expression of osteoprotegerin in normal human osteoblast-like cells

Estrogen/progestins replacement therapy prevents excess bone loss in post-menopausal women. The action of estrogen on bone is mainly through inhibiting bone resorption, but progestins exert its effect mainly through promoting bone formation. Recently osteoprotegerin (OPG) has been identified in osteoblast and displayed to inhibit bone resorption. The present study was performed to compare the action between E2 and P on OPG expression in cultured normal human osteoblast-like cells (hOB). OPG mRNA levels were determined by northern blot analysis, and OPG protein concentrations in conditioned media were determined by western immunoblot analysis and ELISA. After 24-48 h of treatment, E2 at 10(-8) M increased OPG mRNA levels and protein production in cultures of hOB, treatment with increasing dose of E2 caused a dose-dependent increase in the expression of OPG mRNA and protein by hOB. However, we also found out that after 12-48 h of treatment, progesterone at 10(-8) M had no effects on OPG mRNA levels and protein production in cultures of hOB, treatment with increasing dose of progesterone did not regulate the expression of OPG mRNA and protein by hOB. Thus, the data suggest that the different regulation of OPG production in osteoblasts by E2 and P may contribute to the mechanisms by which estrogen or progestins exerts its different action on bone resorption.

Effects of 17beta-estradiol on the expression of membrane type 1 matrix metalloproteinase (MT1-MMP) and MMP-2 in human osteoblastic MG-63 cell cultures

Estrogens are important regulators of bone cell function. Osteoblast-derived membrane type 1 matrix metalloproteinses (MT1-MMP) have recently been implied to play an important role in the process of bone resorption by proteolytically activating latent matrix metalloproteinase-2 (proMMP-2) at the cell surface and degrading tumor necrosis factor-alpha (TNF-alpha). In the present study, we observed the effects of 17beta-estradiol (E2) on MT1-MMP production and subsequent activation of latent matrix proMMP-2, and also proMMP-2 secretion in cultures of human osteoblastic MG-63 cells. Western immunoblot analysis showed that treatment with increasing doses of E2 in MG-63 cells caused a dose-dependent increase in expression of MT1-MMP protein. Confocal immunohistochemistry analysis also confirmed that E2 induced MT1-MMP synthesis in MG-63 cells. We found unexpectedly that although MT1-MMP synthesis was up-regulated by E2 in cultures of MG-63 cells, activation of proMMP-2 was unchanged, which can be attributed partly to the undetectable tissue inhibitor of metalloproteinase-2 (TIMP-2) protein in MG-63 cells by Western immunoblotting. ProMMP-2 production was also not influenced by E2. In conclusion, E2 induces MT1-MMP protein expression in MG-63 cells while it is not followed by proMMP-2 activation, E2 may suppress bone resorption by accentuated degradation of TNF-alpha which mediated through increasingly MT1 -MMP production in osteoblastic cells.

Effects of 17beta-estradiol on the expression of matrix metalloproteinase-1, -2 and tissue inhibitor of metalloproteinase-1 in human osteoblast-like cell cultures

Estrogen can effectively prevent estrogen deficiency-induced bone loss in animals and humans. However, its mechanism remains unknown. Osteoblast-derived Matrix metalloproteinse-1 (MMP-1), MMP-2, and tissue inhibitor of metalloproteinase-1 (TIMP-1) recently were implicated as playing important roles in initiating bone resorption. Therefore, we tested the effects of 17beta-estradiol (E2) on MMP-1, MMP-2, and TIMP-1 production in cultures of human osteoblastic MG-63 cells and normal human osteoblasts (hOB). MMP-1, MMP-2 and TIMP-1 concentrations in the culture medium were determined by ELISA, and activity of MMP-2 was assessed by ELISA. After 12-48 h of treatment, E2 at 10(-8)M decreased MMP-1 level in cultures of MG-63 cells or hOB. Treatment with increasing, dose of E2 in MG-63 cells or hOB caused a dose-dependent decrease in MMP-1 synthesis. E2 had no influence on MMP-2 and TIMP-1 production in MG-63 cells or hOB cultures, as well as activation of latent MMP-2. In conclusion, E2 represses MMP-1 synthesis, and this effect may contribute to its action on the inhibition of bone resorption, followed by prevention of bone loss. Increasing MMP-1 production followed by estrogen deficiency may contribute to the mechanisms involved in postmenopausal osteoporosis.

Progesterone differentially regulates the membrane-type matrix metalloproteinase-1 (MT1 -MMP) compartment of proMMP-2 activation in MG-63 cells

Osteoblast-derived matrix metalloproteinases (MMPs) are considered to play a crucial role in bone formation and initiation of bone resorption by degrading the bone matrix. MMP-2 is constitutively secreted in a latent zymogen by osteoblasts, and requires the process of activation mediated by membrane-type matrix metalloproteinase-1 (MT1-MMP)/tissue inhibitor of metalloproteinase (TIMP-2) complex in the cell surface. Bone is one target tissue for progestins. In the present study, we observed the effects of progesterone on proMMP-2 activation and MT1-MMP expression, and also TIMP-2 levels in osteoblastic MG-63 cells. Gelatin zymograms and ELISA showed that progesterone have no effects on proMMP-2 activation. Using Western immunoblot analysis, we unexpectedly found that treatment with increasing doses of progesterone in MG-63 cells caused a dose-dependent increase in expression of MT1-MMP protein, and after 48h treatment, progesterone at 10(-8)M increased MT1-MMP protein level. Confocal immunohistochemistry analysis also confirmed that progesterone induced MT1-MMP expression in MG-63 cells. The results of Northern blot analysis showed that progesterone at 10(-8)M increased MT1-MMP protein levels after 48 h treatment. We also found that TIMP-2 levels were undetectable in MG-63 cells. In conclusion, progesterone increases MT1-MMP protein and mRNA levels in MG-63 cells, but has no effects on proMMP-2 activation, which is partly attributable to the undetectable levels of tissue inhibitor of metalloproteinase-2 (TIMP-2). Our studies suggest that TIMP-2 is involved in proMMP-2 activation, and regulation of MT1-MMP by progesterone may contribute to its actions on bone formation.

[Comprehensive assessment of the ovariectomized rat model of postmenopausal osteoporosis]

Dual-energy X-ray absorptiometry(DEXA), scanning electron microscopy, and bone biomechanical test were used to assess comprehensively bone quantity and quality of ovariectomized rats. In OVX rats, not only bone mineral density (BMD) of lumbar vertebrae in vivo and vitro, but also BMD of femora (except for R3 region) and proximal metaphysis(R1 region) in vitro decreased obviously (P < 0.01), whose bone loss rates of L5 and L6 were the highest and achieved 13%; the trabeculae of OVX rats were few, fine, and discontinued and there were lacunae on the surface; in OVX rats, both compressive strength of vertebral bodies and the mechanical properties of femora decreased; the falling degree of the former was greater; the maximal compressive power of lumbar vertebrae decreased with 33.32%. We conclude that after 4-month post-ovariectomy, the bone quantity and quality of six-month-old rats decreased, especially in the area of abundant cancellous bone such as vertebral bodies, distal femora; the assessment of the efficiency of new drugs to prevent and treat postmenopausal osteoporosis using rat models should include these drugs' effects to the bone mass, the bone structure, and the bone strength.

[Differentiation and gene expression of human osteosarcoma cell line MG-63]

To observe the differentiation and gene expression of human osteosarcoma cell line MG-63 in culture. Alkaline phosphatase (ALP) activity was determined by p-nitrophenyl phosphate assay; bone Gla protein (BGP) was measured by radioimmunoassay; type I collagen, matrix metalloproteinase (MMP)-1, tissue inhibitor of matrix metalloproteinase (TIMP)-1 mRNA were examined using semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis; MG-63 cells were stained by the Van GieSon method. Type I collagen mRNA expression achieved a maximum level on the 17th day in MG-63 cells; MMP-1 mRNA was not expressed until the 5th day of culture, and gradually increased; TIMP-1 mRNA was nearly constant; ALP activity gradually up-regulated during 0-12 days, and decreased on the 18th day. By Van GieSon staining, MG-63 cells displayed nodule formation at the 12th day, and became more prominent on the 18th day. The results indicate that human osteosarcoma cell line MG-63 has the osteoblast phenotype; during the differentiation of MG-63 cells, there are the following three principle periods: proliferation, extracellular matrix maturation and mineralization.

[Variability of female peak bone mineral density at different skeletal regions and its effect on diagnosis of osteoporosis]

OBJECTIVE

To evaluate the changes in variability (V) of female peak bone mineral density (PBMD) at different skeletal regions and its effects on diagnosis of osteoporosis.

METHODS

Using a Hologic QDR 4500A fan beam X-ray bone densitometer to measure the BMD at different skeletal regions (anteroposterior and supine lateral spine, hip, and forearm) in 1,810 women between the ages of 15-96 from Changsha city (Hunan province) in the People's Republic of China, the population grouped in every 5 years of age, then to get PBMD and its variability.

RESULTS

According to every 5 years of age, the analysis showed that PBMD occurred varied in the age of 20-44, the variability ranged 6.0% to 17.0%, in an average of (11.4 +/- 3.1)%, the maximal value (17%) of V is at Ward's triangle, the minimal value of V is at distal one-third site of forearm (6%). The incidence of osteoporosis changed with V of PBMD at different skeletal regions. With different diagnostic standards, the incidences of OP also differed.

CONCLUSION

Changes in PBMD and its V at different skeletal regions and the different diagnostic standard obviously affects the incidence of OP.

[Approach to application of laser scanning confocal microscope in bone morphometry]

The laser scanning confocal microscope(LSCM) is the new high distinguishing microscope, which can be used in observation on fluorescence, since 1990. The bone morphometry is an important way to study metabolic bone diseases. Our study on research combination of LSCM with bone morphometry in observing microarchitecture of bone found that LSCM could make the photo of bone trabecula distinctly and its location accurately. Because of its technical advantages, LSCM could link histochemical or immunohistochemical method for the bone morphometry and bone cells at the same time and obserrate the thick-slide. It is a new method and way to study and diagnose metabolic bone diseases.

[Bone mineral density characteristics at the femoral neck and Ward's triangle for Chinese women]

The incidence of hip fracture is not as high in Chinese women compared to women from Western countries, though they usually have low bone mineral density(BMD) and get osteopenia easily. In this study, reference data(white women) supplied by the manufacturer of Hologic was compared with data obtained from healthy women in Changsha, Hunan, P.R.C. One thousand four hundred and eighty-eight Chinese women aged 15 to 95 years were randomly recruited. Measurements of BMD were taken at the hip by the dual energy x-ray absorptiometry(QDR 4,500A, Hologic Inc., USA). The BMD was somewhat lower than reference curves at all ages and all sites. But at the femoral neck and Ward's triangle, Chinese women reached their peak BMD 5 to 10 years later than the reference group, and had a lower BMD rate of decrease for about 35 years after peak BMD was reached. Whether the differences(i.e., longer time to peak BMD and a lower BMD decrease rate at the neck and Ward's triangle after the peak BMD reached) will result in a protection from hip fractures for Chinese women needs to be studied in the future.

[Study on the prevention of insulitis and diabetes by complete Freund's adjuvant in NOD female mice]

The degrees of insulitis, the incidence of diabetes, and the counts of alpha,beta and delta cells in islets were studied by morphological method and avidin-biotin complex immunohistochemical method in complete Freund's adjuvant(CFA) or normal saline(NS)-treated non-obese diabetic(NOD) female mice. The results showed: The incidences of in-insulitis and the scoring means were significantly lower in CFA-treated mice than those in NS-treated ones; none of 5 CFA-treated mice and 3 out of 5 NS-treated ones developed diabetes. The positive rates of alpha, and delta cells were significantly lower in CFA-treated mice than those in NS-treated ones, but the positive rate of beta cell was significantly higher in CFA-treated mice than that in NS-treated ones. The correlations were found among the scores of insulitis and the positive rates of alpha, beta, delta cells in islets (r alpha = 0.475, r beta = -0.878, r delta = 0.869). The results indicate that CFA may lessen the degrees of insulitis and the incidence of diabetes. Its effects might be related to lessen the damage of beta cell in islets.

[The diagnosis and management of adrenal "incidentaloma"]

We reported seven patients with adrenal "incidentaloma", diagnosed with ultrasonography and/or computed tomography and confirmed by operation and pathological examination. Three of them were pathologically diagnosed as pheochromocytoma and one each as mixed cell adenoma, bilateral adrenocortical adenoma, leiomyoma and adrenocortical carcinoma. Only one "incidentaloma" had cortisol-secreting function. The diagnosis and management of adrenal "incidentaloma" were discussed.