Degradable poly(anhydride ester) implants: effects of localized salicylic acid release on bone

Degradable poly(anhydride ester) implants in which the polymer backbone breaks down into salicylic acid (SA) were investigated. In this preliminary work, local release of SA from the poly(anhydride esters), thus classified as ‘active polymers', on healthy bone and tissue was evaluated in vivo using a mouse model. Degradable polyanhydrides that break down into inactive by-products were used as control membranes because of their chemical similarity to the active polymers. Small polymer squares were inserted over the exposed palatal bone adjacent to the maxillary first molars. Active polymer membranes were placed on one side of the mouth, control polymers placed on the contra lateral side. Intraoral clinical examination showed that active polymer sites were less swollen and inflamed than control polymer sites. Histopathological examination at day 1 showed essentially no difference between control and active polymers. After 4 days, active polymer sites showed epithelial proliferation to a greater extent than the polyanhydride controls. After 20 days, active polymer sites showed greater thickness of new palatal bone and no resorptive areas, while control polymer sites showed less bone thickness as well as resorption including lacunae involving cementum and dentine. From these preliminary studies, we conclude that active polymers, namely poly(anhydride esters), stimulated new bone formation.     

肾性骨病的骨膜下骨吸收

笔者采用手骨直接Ｘ线放大摄影和双手Ｘ线平片来研究慢性肾衰血透病人５１例。特征性的指骨骨膜下吸收放大摄影发现２５例占４９％;平片为１１例占２１．６％,结果表明,放大摄影的阳性率明显高于平片（Ｐ＜０．００５）,骨膜下吸收的二,三指中间指骨桡侧及指骨末端是肾性骨病的“靶区”,认为二者无显著差异（Ｐ＞０．５０）。骨膜下吸收还与血透时间,血磷,血钙和碱性磷酸酶水平相关。     

动力加压髁螺钉治疗股骨髁部骨折临床与实验研究

本研究结合１４例股骨髁间、髁上骨折以动力加压髁螺钉（Ｄynamic Ｃondylar Ｓcrew ＤＣＳ）固定。目的：为临床提供应用ＤＣＳ的实验数据。方法：采用成人新鲜尸体股骨髁部标本,按照ＡＯ/ＡＳＩＦ分类,模拟Ｙ形骨折模型,以ＤＣＳ固定,置于ＷＤ－１０Ｅ万能电子力学实验机上其抗拉伸、抗扭转、抗村缩、抗剪切强度。结果：ＤＣＳ有较好的固定强度。临床应用１４例,随访６个月至１年,优良率为８５．７１％。结论：ＤＣＳ适合于     

Tissue inhibitors of metalloproteinases (TIMP-1 and TIMP-2) stimulate osteoclastic bone resorption

As both tissue inhibitor of metalloproteinases-1 (TIMP-1) and TIMP-2 have been reported to inhibit bone resorption, we examined whether TIMP-1 or TIMP-2 in fetal calf serum (FCS), with which culture media were supplemented, affected osteoclastic bone resorption in vitro. Contrary to our expectation, almost complete suppression of osteoclastic bone resorption was observed when both TIMP-1 and TIMP-2 were removed from the FCS. Bone resorption was, however, almost fully restored by the addition of recombinant TIMPs. TIMPs stimulate bone resorption at significantly lower concentrations (∼ng/ml) than those (∼μg/ml) required to inhibit bone resorption. To understand the mechanism of TIMP-dependent bone resorption, we counted and compared the number of tartrate-resistant acid phosphatase-(TRAP-) positive and multinuclear cells in cultures containing either 10% FCS or TIMP-1-free and/or TIMP-2-free FCS. There was essentially no difference in number among these, suggesting that the TIMP role seems to be related to the functional expression of osteoclasts. Metallo-proteinase inhibitors, either BE16627B[l-N-(N-hydroxy-2-isobutylsuccinynamoyl)-seryl-l-valine] or R94138 {N-methyl-(3S)-2-[(2R)-2-hydroxycarbamoylmethylundecanoyl] hexahydropyridazine-3-carboxamide}, could not replace TIMPs, suggesting that the osteoclast-stimulating activity of TIMPs cannot be ascribed to merely their inhibitory effect on matrix metalloproteinases. Received: Oct. 15, 1998 / Accepted: April 5, 1999