Different effects of 25-kDa amelogenin on the proliferation, attachment and migration of various periodontal cells

Previous studies have assumed that amelogenin is responsible for the therapeutic effect of the enamel matrix derivative (EMD) in periodontal tissue healing and regeneration. However, it is difficult to confirm this hypothesis because both the EMD and the amelogenins are complex mixtures of multiple proteins. Further adding to the difficulties is the fact that periodontal tissue regeneration involves various types of cells and a sequence of associated cellular events including the attachment, migration and proliferation of various cells. In this study, we investigated the potential effect of a 25-kDa recombinant porcine amelogenin (rPAm) on primarily cultured periodontal ligament fibroblasts (PDLF), gingival fibroblasts (GF) and gingival epithelial cells (GEC). The cells were treated with 25-kDa recombinant porcine amelogenin at a concentration of 10 μg/mL. We found that rPAm significantly promoted the proliferation and migration of PDLF, but not their adhesion. Similarly, the proliferation and adhesion of GF were significantly enhanced by treatment with rPAm, while migration was greatly inhibited. Interestingly, this recombinant protein inhibited the growth rate, cell adhesion and migration of GEC. These data suggest that rPAm may play an essential role in periodontal regeneration through the activation of periodontal fibroblasts and inhibition of the cellular behaviors of gingival epithelial cells.     

Kinetic resolution of organosilicon compounds by stereoselective dehydrogenation with horse liver alcohol dehydrogenase

Streoselective dehydrogenation of three isomers of trimethylsilypropanol was carried out with horse liver alcohol dehydrogenase (HLADH, EC 1.1.1.1.) and optically active organosilicon compounds were obtained in a water-organic solvent two-layer system with coenzyme regeneration. Furthermore, we examined the effects of the silicon atom on stereoselectivity of HLADH compared to the corresponding carbon compounds. Substitution of the silicon atom for the carbon atom was found to improve the stereoselectivity of HLADH. For example, the optical purity of the remaining 1-trimethylsilyl-2-propanol was higher than 99% enantiomeric excess (ee) at 50% conversion, whereas that of the carbon analogue was 84% ee. This phenomenon was probably ascribable to the bulkiness of the organosilicon compounds derived from their longer Si-C bond. Kinetic analysis in an aqueous monolayer system demonstrated that the specific properties of the silicon atom greatly affected the reactivity of these substrate compounds.Correspondence to: A. Tanaka     

Determinants of growth-promoting activity reside in the A-domain of insulin-like growth factor I

A two-chain, disulfide linked, insulin-like compound embodying the A-domain of insulin-like growth factor I (IGF-I) and the B-chain of insulin has been synthesized and characterized with respect to insulin-like biological activity and growth-promoting potency. The compound displays a potency of ca. 41% relative to insulin in assays for insulin-like activity (e.g., lipogenesis) but significantly higher activity than insulin, ca. 730% relative to insulin, in growth factor assays (e.g., thymidine incorporation). The compound is, however, a less potent growth factor than IGF-I itself, ca. 26.5% relative to IGF-I, and is not recognized by IGF carrier proteins. We conclude that structural features contained in the A-domain of IGF-I are primarily responsible for the growth-promoting ability displayed by IGF-I, while features in the B-domain are responsible for recognition by IGF carrier proteins.     

Genistein对腺样囊性癌cyclinB1蛋白表达和细胞增殖周期的影响

目的研究酪氨酸蛋白激酶抑制剂genistein抑制人涎腺腺样囊性癌(SACC-83)细胞生长与cyclin B1蛋白表达和细胞增殖周期的关系.方法 MTT法测定genistein对SACC-83细胞体外生长的作用;流式细胞仪测定细胞增殖周期;Western Blot技术检测cyclin B1和Cdk1蛋白,并利用电泳凝胶成像分析软件对其结果进行量化分析;采用SPSS11.5统计软件对结果进行统计学分析.结果 Genistein对SACC-83细胞生长有抑制作用,且当其作用到一定时间达到一定的浓度后,该作用与剂量及时间呈依赖关系;Genistein作用的细胞与对照细胞比较,G0/G1期细胞数减少, G2/M期细胞数增多,cyclin B1和Cdk1蛋白水平降低.结论 Genistein对SACC-83细胞生长的抑制作用与其调节cyclin B1和Cdk1蛋白表达和细胞增殖周期有关.     

Synthesis of (R)-2-trimethylsilyl-2-hydroxyl-propionitrile catalyzed by (R)-hydroxynitrile lyase from Prunus japonica seed meal

Synthesis of (R)-2-trimethylsilyl-2-hydroxyl-propionitrile via asymmetric transcyanation of acetyltrimethylsilane with acetone cyanohydrin in an aqueous/organic biphasic system catalyzed by (R)-hydroxynitrile lyase from Prunus japonica seed meal was successfully carried out for the first time. The optimal volume ratio of aqueous to organic phase, buffer pH value and reaction temperature were 15% (v/v), 5.0 and 30°C, respectively, under which both substrate conversion and product enantiomeric excess (ee) were 99%. Silicon atom in the substrate showed great effect on the reaction. Acetyltrimethylsilane was a much better substrate for (R)-hydroxynitrile lyase from Prunus japonica than its carbon analogue.     

小鼠受精卵中蛋白激酶C底物的鉴定

为研究蛋白激酶C（protein kinase C,PKC）在小鼠早期发育中的调节作用,运用超排卵和体外受精技术,采用体外磷酸化和放射自显影的方法,鉴定小鼠1-细胞期受精卵中PKC的底物。经特殊的反复冻融处理,消除卵中内源性蛋白激酶活性。55个受精卵的样品中加入部分纯化的PKC,结合应用较强的PKC抑制剂H-7和星形孢菌素以及促分裂原活化蛋白激酶抑制剂PD098059作为对照,观察到12条PKC底物蛋白的放射自显影带,根据标准蛋白质对值绘制的标准曲线计算,这些磷酸化蛋白的相对分子量分别约为120kDa、100kDa、79kDa、63kDa、59kDa、47kDa、40kDa、34kDa、32kDa、26kDa、24kDa和22kDa。实验结果表明,PKC可通过底物蛋白活性的调节,在小鼠早期发育中发挥重要作用。