一成骨不全家系的COL1A1基因突变检测

成骨不全(Osteogenesisimperfecta,OI)是一种由于Ⅰ型胶原形成障碍,导致骨脆性增强为主要症状的 常染色体显性遗传性疾病。临床上主要表现为骨质脆弱、蓝巩膜、耳聋和中等程度的关节畸形等症状。成骨不全 基因分别定位于17q21.31 q22和7q22.1,其致病基因分别为COL1A1和COL1A2。对一常染色体显性遗传的 成骨不全家系进行连锁分析,在COL1A1遗传位点发现紧密连锁(LOD=9.31;θ=.00)。突变检测发现在 COL1A1基因第26内含子5′端剪接位点处存在一由GT转换为AT的致病突变,该突变引起的异常剪接是导致成 骨不全的致病原因之一。     

钛镍记忆合金牵张器复合脱细胞真皮基质增高犬牙槽嵴的初步研究

目的用成年杂种犬建立钛镍记忆合金牵张器复合脱细胞真皮基质增高犬牙槽嵴动物模型,为下一步利用钛镍记忆合金牵张器行下颌后牙牙槽嵴增高术奠定基础。方法健康成年雄性杂种犬4只。全麻下拔除双侧下颌4个前磨牙和第一磨牙,1个月后拍摄双侧后牙区X线光片,观察拔牙窝愈合情况。采用4种类型的牵张器随机在4只犬的下颌两侧行牵张手术并观察牵张后1周和1月牙槽嵴增高的情况。结果拔牙后1个月,牙槽嵴黏膜愈合良好。X线片示下颌神经管清晰可见,其上方牙槽窝内有较低密度骨质存在。放置4种牵张器牵张术后1周、1月后牙槽嵴增高的高度分别为3.24 mm、3.76 mm、4.58 mm、5.09 mm;3.15 mm、3.67 mm、4.64 mm、5.01mm,术后一周X线可见后有明显的牵张间隙,1月时牵张区有新骨形成,骨密度增高。结论犬耐受力强,后牙区下颌骨体积大,手术易操作,是理想的牙槽嵴萎缩动物模型。拔牙后1个月,拔牙创愈合良好,可以进行牵张手术。D组＂S＂形牵张器牵张后的高度比较理想,能满足后期种植体的植入。     

Sensitivity of spatially offset Raman spectroscopy (SORS) to subcortical bone tissue

The development of spatially offset Raman spectroscopy (SORS) has enabled deep, non‐invasive chemical characterization of turbid media. Here, we use SORS to measure subcortical bone tissue and depth‐resolved biochemical variability in intact, exposed murine bones. We also apply the technique to study a mouse model of the genetic bone disorder osteogenesis imperfecta. The results suggest that SORS is more sensitive to disease‐related biochemical differences in subcortical trabecular bone and marrow than conventional Raman measurements.     

The use of XFEM to assess the influence of intra-cortical porosity on crack propagation

This study aimed at using eXtended finite element method (XFEM) to characterize crack growth through bone’s intra-cortical pores. Two techniques were compared using Abaqus: (1) void material properties were assigned to pores; (2) multiple enrichment regions with independent crack-growth possibilities were employed. Both were applied to 2D models of transverse images of mouse bone with differing porous structures. Results revealed that assigning multiple enrichment regions allows for multiple cracks to be initiated progressively, which cannot be captured when the voids are filled. Therefore, filling pores with one enrichment region in the model will not create realistic fracture patterns in Abaqus-XFEM.     

EFFECTS OF BETA MERCAPTOETHANOL ON THE PROLIFERATION AND DIFFERENTIATION OF HUMAN OSTEOPROGENITOR CELLS

Antioxidants are known to influence metabolism and promote cell survival in a number of cell culture systems. However, their effects on the modulation of bone cell differentiationin vitroare not clearly defined. In the present studies we have investigated the effects of β-mercaptoethanol (βME) and ascorbate alone and in combination on human osteoprogenitors derived from bone marrow fibroblasts. In primary marrow cultures, βME stimulated colony formation (2-fold), alkaline phosphatase activity (3.5-fold) and, increased DNA synthesis (8-fold) after 21 days. Cell proliferation was increased significantly by βME during the first 4 days of a 10-day culture period, indicating stimulation of marrow osteoprogenitor proliferation. Ascorbate did not significantly augment the effects of βME in primary cultures or long-term cultures of passaged bone marrow fibroblasts. These findings indicate a potential beneficial role for βME addition for the optimal maintenance of colony formation, cell proliferation and differentiation of marrow osteoprogenitor cells in primary human bone marrow fibroblast cultures.     

Opposing effects by glucocorticoid and bone morphogenetic protein-2 in fetal rat bone cell cultures

Glucocorticoid in excess produces bone loss in vivo. Consistent with this, it reduces the stimulatory effect of transforming growth factor β (TGF-β) on collagen synthesis in osteoblast-enriched cultures in vitro, where it also suppresses TGF-β binding to its type I receptors. Analogous studies with bone morphogenetic protein-2 (BMP-2) show directly opposite results. These findings prompted us to assess the effect of glucocorticoid on BMP-2 activity in cultured bone cells, and whether either agent had a dominant influence on TGF-β binding or function. BMP-2 activity was retained in part in osteoblast-enriched cultures pre-treated or co-treated with cortisol, and was fully evident when glucocorticoid exposure followed BMP-2 treatment. In addition, BMP-2 suppressed the effects of cortisol on TGF-β activity, on TGF-β binding, and on gene promoter activity directed by a glucocorticoid sensitive transfection construct. While BMP-2 also alters the function of less-differentiated bone cells, it only minimally prevented cortisol activity in these cultures. Our studies indicate that BMP-2 can oppose certain effects by cortisol on differentiated osteoblasts, and may reveal useful ways to diminish glucocorticoid-dependent bone wasting. J. Cell. Biochem. 67:528–540, 1997. © 1997 Wiley-Liss, Inc.