不同应变水平拉伸对成骨细胞生理功能的影响

采用四点弯曲加载装置对大鼠颅盖骨中分离出的成骨细胞施加周期性拉伸刺激，研究成骨细胞对不同应变水平的拉伸刺激的生理响应。结果表明，500微应变的周期性拉伸刺激促进了成骨细胞的增殖，细胞的^3H－脯氨酸掺入量增加，碱性磷酸酶（ALP）活性和向胞外分泌钙均升高；而1000微应变的周期性拉伸抑制了成骨细胞的增殖、^3H－脯氨酸掺入量、碱性磷酸酶活力和向胞外分泌钙都降低，说明成骨细胞能够分辨不同变水平的力学刺激，500微应变的周期性拉伸刺激有利于细胞的生长和分化，而1000微应变的周期性拉伸对细胞的生理活性有抑制作用。而且细胞在增殖、基质合成和分化、矿化上表现出一致的变化趋势。     

Tumor necrosis factor-α inhibits collagen synthesis in human and rat granulation tissue fibroblasts

The purpose of the study was to examine the effects of tumor necrosis factor- (TNF-) on collagen gene expression in rat and human granulation tissue fibroblast cultures. The cells were exposed to 0.1, 1, 10, or 100 ng/ml of TNF-, and the rate of collagen synthesis was measured as synthesis of protein-bound³H-hydroxyproline. Total cellular RNA was isolated from fibroblasts, and measurements of specific cellular RNAs from fibroblasts were performed by Northern blot hybridizations using³²P-labeled cDNA probes. In cultures of rat granulation tissue fibroblasts TNF- decreased³H-hydroxyproline production to about 75% of that in controls and it also decreased pro1(I) and pro1(III) collagen mRNA levels, maximally to 33% and 23% of the control levels, respectively. In cultures of human granulation tissue fibroblasts a similar inhibiting effect in the production of collagen was seen. TNF- decreased the production of³H-hydroxyproline to 56% of the control value with a dose of 100 ng/ml also having an inhibiting effect on pro1(I) collagen mRNA levels of up to 43% of the control level. However, no effect was seen on pro1(III) collagen mRNA levels.     

The biochemistry of ancient DNA in bone

The amount of DNA in ancient bone was determined by ethidium bromide staining after the removal of the potent Taq inhibitor, fulvic acid. A complete decalcification and a perfusion protocol were used to recover DNA from bone. A variety of purification techniques including molecular sieve, hydroxyapatite binding and Magic preparations yielded DNA that spanned from 3.4g/g of bone to below detectable limits. Fulvic acid was shown to interfere with the quantification of DNA derived from ancient human skeletal material one hundred to over seven thousand years old. Scanning UV in the 300 to 230 nm range is a simple and sensitive technique for documenting fulvic acid contamination in ancient bone extracts.     

Structure of rat tail tendon collagen examined by atomic force microscope

The Atomic Force Microscope (AFM) was used to inspect collagen fibrils deposited on mica sheets at different fibrillogenesis times. Collagen was obtained from rat tail tendon fibers. Various fibril forms were observed, together with the characteristic periodic intra-fibril structure (D-bands). The fibril thickness, width, D-band periodicity and depth were measured and the statistical distribution of these parameters at 1, 2, 5, 10 and 15 days of in vitro fibril formation time was calculated. The fibrils showed an increasing size with time, but the band interval measure remained stable. The band depth, after an initial increase, exhibited a relative steadiness. The results indicate that AFM offers, at low resolution, images qualitatively similar to those obtained with electron microscopy, but with less manipulation of the sample. A quantitative evaluation of collagen structural features in the nanometer scale is made possible by AFM.     

木瓜提取液对大鼠骨组织中ColⅠ和Cath L表达的影响

将50只SD雌性大鼠随机分为5组,连续给木瓜提取液12周后,测定大鼠Ⅰ型胶原(ColⅠ)、组织蛋白酶L(Cath L)、Ⅰ型前胶原氨基端前肽(PINP)、Ⅰ型胶原交联羧基末端肽(ICTP)并行股骨并进行形态学分析.结果表明:木瓜提取液组与雌激素组能显著增加大鼠的骨小梁的数量、降低Cath L的表达,木瓜高剂量组与雌激素组无明显差异(P0.05),这一作用在高剂量组更加明显.木瓜提取液能够降低破骨细胞Cath L的表达来抑制骨基质中ColⅠ的分解,从而起到抗骨质疏松的疗效和骨保护作用.     

Carbon and nitrogen stable isotope analyses of mammal bone fossils from the Zhongba site in the Three Gorges Reservoir region of the Yangtze River,China

Based on AMS ¹⁴C dating data, carbon and nitrogen isotope analyses were conducted on mammal bone collagen of deer, cattle and pigs from the Zhongba site in the Three Gorges Reservoir region of the Yangtze River. These analyses were conducted to reconstruct palaeodiets of mammals, palaeoecology, palaeoenviroment and previous human activities in the study area. Results show that the collagen loss of bone did not change the in vivo isotopic composition of carbon and nitrogen stable isotopes, and most of the bone fossils were well preserved. The bone collagen of samples from deer had a mean δ¹³C of -23.1‰ and a mean δ¹⁵N of 4.7‰, suggesting that deer subsisted in a closed habitat and fed on branches and leaves. The bone collagen of cattle had a mean δ¹³C of –19.6‰ and a mean δ¹⁵N of 5.2‰, which indicates that cattle subsisted in an open habitat and fed on grasses and stems. The δ¹³C values show that both deer and cattle fed on C₃ plants and lived in the same ecosystem, but the t-test results show that deer δ¹³C and δ¹⁵N values were both more negative than those of cattle, indicating that they inhabited different niches. The δ¹³C and δ¹⁵N values of cattle partially overlapped those of deer, suggesting some competition in diets between them. The t-tests show that the δ¹³C and δ¹⁵N values of pigs were more positive than those of cattle and deer, which signifies that pigs occupied a higher trophic level compared to cattle and deer. The wide range of pig δ¹³C values demonstrates that pig trading had been taking place from early Neolithic Age to late Bronze Age. There were no significant differences in deer δ¹³C and δ¹⁵N values among different archaeological periods, making it clear that climatic, ecological and environmental conditions were kept relatively stable from 2200 to 4200 a BP. This stability may have been responsible for the extensive and complete cultural layers at the Zhongba site. The minimum number of samples required to estimate the mean δ¹³C values of deer, pigs and cattle are 8, 73 and 16, respectively, and for mean δ¹⁵N values of deer, pigs and cattle, the minimum numbers are 4, 5 and 6, respectively.     

基因重组酵母工程菌优化表达人源胶原蛋白

通过响应曲面法(RSM)优化巴氏毕赤酵母基因工程菌GS115/pPIC9KG6表达高亲水性重组人源胶原蛋白的摇瓶培养条件。采用Box-Behnken设计(BBD)考察初始诱导pH值、温度和甲醇添加量三个主要影响因子对重组人源胶原蛋白表达量的影响,利用DX7Trial软件设计实验方案,根据该方案设置不同培养条件进行实验并测定相关参数。响应面分析确定的最优因素水平组合为:初始诱导pH值为5.0,诱导温度为28℃,甲醇添加量为2.2%/24 h。通过响应面法优化发酵的内在因素水平,找出最佳条件,为利用其指导在发酵罐中进行高密度发酵生产人源胶原蛋白奠定基础。     

一种胶原蛋白寡肽对人皮肤成纤维细胞增殖及胶原分泌的影响

研究了罗非鱼鱼鳞胶原蛋白寡肽对体外培养人皮肤成纤维细胞增殖与Ⅰ型胶原蛋白分泌的影响.采用WST-8法测定了胶原蛋白寡肽对人皮肤成纤维细胞增殖的影响,采用ELISA法检测了胶原蛋白寡肽对人皮肤成纤维细胞Ⅰ型胶原蛋白分泌的影响.实验表明,罗非鱼鱼鳞胶原蛋白寡肽能促进人皮肤成纤维细胞增殖(P＜0.01),以及人皮肤成纤维细胞...     

海洋胶原肽对SD大鼠生存时间的影响

为探讨海洋胶原肽长期喂养对SD大鼠生存时间的影响,选用4周龄SD大鼠160只,随机分为空白对照组和3个剂量的MCP干预组,每组40只,雌雄各半.对照组和3个剂量的MCP干预组的大鼠分别给予普通标准饲料和在对照组饲料的基础上分别添加2.25%、4.5%和9%的MCP干预组饲料至自然衰老死亡.实验过程中记录大鼠的体重、摄食量、食物利用率,每6月对大鼠血清的抗氯化相关指标超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-PX)活性及丙二醛(MDA)水平进行检测.生存分析结果表明,3个剂量的MCP干预组的中位生存时间,尤其是最后30%存活动物的生存时间均显著长于对照组;在干预18和24月时,4.5%和9%MCP干预组的血清SOD酶和GSH-PX的活性在雌雄大鼠均显著高于对照组,而MDA的水平则显著低于对照组.本研究表明,一定剂量的MCP长期干预可对大鼠生存时间有一定的延长作用,而MCP对SD大鼠衰老过程中机体抗氧化能力的提高作用可能是其中机制之一.     

胶原修饰快速成形PLGA/TCP人工骨支架体外生物相容性研究

探讨经Ⅰ型胶原修饰的快速成型(RP)聚乳酸-羟基乙酸/磷酸三钙(PLGA/TCP)支架的生物相容性,为进一步体内实验提供研究基础.以经Ⅰ型胶原修饰改性的PLGA/TCP支架作为实验组,未经胶原修饰的原始支架作为对照组,检测两组支架材料的亲水性.BMSCs接种两组支架,分别测定细胞黏附率、细胞增殖率.扫描电镜(SEM)观察细胞黏附形态,以检验支架材料的细胞相容性.结果表明胶原改性支架具有较高的亲水性,实验组细胞黏附率在接种4、8和12 h者,明显优于对照组(P<0.05).实验组在培养2、4、6和8 d的细胞增殖率也明显高于对照组(P<0.05).扫描电镜可见骨髓基质细胞在实验组支架上的增殖数量多于对照组.说明Ⅰ型胶原改性的PLGA/TCP支架具有良好的细胞生物相容性,可作为骨组织工程支架应用于骨缺损的修复研究.