Alternative splicing and expression of the insulin-like growth factor （IGF-1） gene in osteoblasts under mechanical stretch

Insulin-like growth factor 1 (IGF-1) promotes osteoblasts differentiation and bone formation, and its expression is induced by mechanical stretch, thus IGF-1 has been considered an effector molecule that links mechanical stimulation and local tissue responses. In this study, a mechanical stretching device was designed to apply physiological level static or cyclic stretching stimulation to osteoblasts. Different isoforms of IGF-1 mRNA were amplified by RT-PCR from the cells using respective primers and these amplified products were sequenced. An iso-form of IGF-1 splicing product was found to be selectively produced by osteoblasts under stretching stimulation. This IGF-1 isoform had identical sequence with the mechano growth factor (MGF) which was originally identified in muscle cells. Regulations of the expression of the liver-type IGF (L.IGF-1) and MGF in osteoblasts under stretch stimulation were further studied using semi-quantitative RT-PCR. Stretch stimulation was found to promot the expression of IGF-1 (L.IGF-1 and MGF), and for both isoforms expression was more effectively stimulated by cyclic stretch than static stretch. MGF was detected only in osteoblasts subjected to mechanical stretch, suggesting MGF was a stretch sensitive growth factor. Expression of MGF peaked earlier than that of L.IGF-1, which was similar to their regulation in muscle and suggested similar roles of MGF and L.IGF-1 in bone as in muscle cells. The functions of MGF and LIGF-1 in osteoblasts shall be established by further experimental studies.     

The autooxidation of 2,3,5,6-tetrahydroxy-2,5-cyclohexadiene-1,4-dione under physiological conditions

Summary A radical anion of 2,3,5,6-tetrahydroxy-2,5-cyclohexadiene-1,4-dione was detected using the EPR technique by complexing with Zn ions. Hydrogen peroxide, superoxide radical anion and hydroxyl radical were also detected in the reaction mixture. Kinetic study and product distribution indicated a probable mixed type one- and two-electron transfer mechanism. A possible relationship between the autooxidation process and the biological activity of substituted quinones was suggested.     

Retroviruses released from a human tumor xenograft in nude mice induce colony-stimulating factor (CSF) activity in human fibroblastic cells

Summary A human colony-stimulating factor (CSF)-producing tumor transplanted into athymic nude mice released retroviruses in vitro. The viruses induced CSF activity in human fibroblastic cell lines.     

科学基金综合评价指标体系优化的因子分析

在对因子分析方法进行理论探讨的基础上，将其引入科学基金综合评价指标体系的优化研究，取得了满意的结果．其思路和方法对类似问题的研究有参考价值．     

Cytosolic factors in mitochondrial protein import

In vitro import studies have confirmed the participation of cytosolic protein factors in the import of various precursor proteins into mitochondria. The requirement for extramitochondrial adenosine triphosphate for the import of a group of precursor proteins seems to be correlated with the chaperone activity of the cytosolic protein factors. One of the cytosolic protein factors is hsp70, which generally recognizes and binds unfolded proteins in the cytoplasm. Hsp70 keeps the newly synthesized mitochondrial precursor proteins in import-competent unfolded conformations. Another cytosolic protein factor that has been characterized is mitochondrial import stimulation factor (MSF), which seems to be specific to mitochondrial precursor proteins. MSF recognizes the mitochondrial precursor proteins, forms a complex with them and targets them to the receptors on the outer surface of mitochondria.     

多功能机械传动试验台的能量回输效益和宽适应性分析

本文对采用直流电能回输方式的多功能机械传动试验台,在叙述其能量回输原理和控制方式的基础上,进行能量回输的效益分析,提出了利用系数的概念,对试验台允许试件传动比在大范围内变化这一宽适应性特点,进行了着重的分析。     

REMARKS ON THE BINDING NUMBER FOR [a,b]-FACTORS

We give some answers to the following question:If the binding numberof a graph G is more than 1+(a-1)/b,does G have an [a,b] -factor?     

企业并购中的文化整合风险及防范措施

企业文化是企业在长期经营活动中逐渐形成的一套价值观和行为规范。在并购失败的决定因素中,文化的差异性居首位。因此必须识别并购中的文化风险,采取有效的防范与控制措施,以保证并购成功。文化风险因素中的文化整合风险因素可分为两个维度下的四种类型,分别是相容型、模糊性、磨擦型、冲突型。依据对文化风险类型的分析,开展并购开始前的文化评估工作,选择适当的文化整合方式,协调与其它整合工作的关系等防范措施是必要的。     

人脐静脉内皮细胞原代培养方法的建立

目的：探索并建立人脐静脉内皮细胞（删Ⅶc）体外稳定培养的方法。方法：以1％Ⅱ型胶原酶消化收集人脐静脉内皮细胞，用嘲加10％的胎牛血清进行培养，免疫细胞化学方法鉴定内皮细胞。结果：原代培养的内皮细胞镜下呈典型的铺路石或者鹅卵石样排列，3～4d时生长最快。5d左右融合；免疫细胞化学染色显示内皮细胞Ⅷ因子相关抗原表达阳性。结论：酶消化法获得的原代血管内皮细胞有较高的存活率，可以作为基础和临床研究的良好模型。