冯元桢等的理论分析表明，在一定条件下血管内皮细胞膜张应力会逆血流方向累加。此结果意义重大，但实验验证尚难。本文试图通过不同长度的内皮细胞单层的In vitro实验为此求得一种证据。人胚肾小球血管内皮细胞（HGVEC）单层暴露在平面剪切流场中（切应力水平为0.45N/m2)24h，两种不同长度（10cm和6cm）单层内皮细胞的内皮素（ET-1）累积分泌量、平均分泌速率、最大分泌速率、最小分泌速率及分泌率变异系数以及血管紧张素II（ATII）的累积分泌量、平均分泌速率等均有显著差异。其中，在前述两种长度下，平均分泌率比值，ET-1为2. 7:1，ATII为1.5:1。而在0.65N/m2切应力作用10h条件下，相应的比值同为1.5:1。本试验结果表明在相同切应力条件下，单层内皮细胞长度与其蛋白质代谢有密切的相关，进而从一个侧面证明血管内皮细胞膜张应力存在累加效应。

A novel atomic electronegative distance vector (AEDV) has been developed to express the chemical environment of various chemicaUy equivalent carbon atoms in alcohols and alkanes. Combining AEDV and γ parameter, four five-parameter lin-ear relationship equations of chemical shift for four types of carbon atoms are created by using multiple linear regression. Correlation coefficients are R=0.9887, 0.9972, 0.9978 and 0.9968 and roots of mean square error are RMS=0.906, 0.821, 1.991 and 1.091 of four types of carbons, i.e., type 1, 2, 3, and 4 for primary, secondary, tertiary, and quater-nary carbons, respectively. The stability and prediction ca-pacity for external samples of four models have been tested by cross-validation.

Mechanical forces regulate the function of bone cells. In this paper, the effects of cyclic stretching on osteoblasts derived from rat calvaria were studied at a magnitude occurring in physiological loaded bone tissue. A four-point bending apparatus was used to apply cyclic stretching on osteoblasts. Stretching at 500 me for 2-24h resulted in an increase in matrix synthesis(Po0:01). In contrast, the cyclic stretching at 1000 and 1500me for 2-24h inhibited osteoblast collagen production (Po0:01). We also described our newloading method to increase strain magnitude step-by-step. The strain magnitude increased by 500me increments from 500 to 1500me every 2 or 12h, respectively. Results showed that osteoblasts could absorb large amount of proline for collagen synthesis when stretched at 500me. However, not all the absorbed proline was used to synthesize collagen. Some of it was stored in cells. When the suitable signal (500me) was changed to an inhibiting signal (1000me), cells responded to it accordingly and released proline to medium. These results demonstrate that the response of osteoblasts is dependent on the magnitude of the strain applied and cells can adjust their bio-chemical response to adapt to the changing environmental stimulation.

AIM: To discover compounds which can regulate Klotho promoter activity. Klotho is an aging suppressor gene. A defect in Klotho gene expression in the mouse results in the phenotype similar to human aging. Recombinant Klotho protein improves age-associated diseases in animal models. It has been proposed that up-regulation of Klotho gene expression may have anti-aging effects. METHODS: Klotho promoter was cloned into a vector containing luciferase gene, and the reporter gene vector was transfected into HEK293 cells to make a stable cell line (HEK293/KL). A model for cellular aging was established by treating HEK293/KL cells with H2O2. These cells were treated with extracts from Traditional Chinese Medicines (TCMs). The luciferase activity was detected to identify compounds that can regulate Klotho promoter. RESULTS:The expression of luciferase in these cells was under control of Klotho promoter and down-regulated after H2O2 treatment. The down-regulation of luciferase expression was H2O2 concentration-dependent with an IC50 at approximately 0.006%. This result demonstrated that the Klotho gene promoter was regulated by oxidative stress. Using the cell-based reporter gene assay, we screened natural product extracts for regulation of Klotho gene promoter. Several extracts were identified that could rescue the H2O2 effects and up-regulated Klotho promoter activity. CONCLUSION: A cell -based assay for high-throughput drug screening was established to identify compounds that regulate Klotho promoter activity, and several hits were discovered from natural products. Further characterization of these active extracts could help to investigate Klotho function and aging mechanisms.

Human glomerular microvascular endothelial cell (HGMEC) culture monolayers were maintained in static culture as controls or subjected to steady laminar shear stress of 0.5, 1.0, or 1.5N/m2. Over 25 h of shear, the cumulative secretion of ET-1 was 705.4pg/cm2 in the control, 820.7pg/cm2 at 0.5 N/m2, 1063.2pg/cm2 at 1.0N/m2, and 644.7pg/cm2 at 1.5N/m2. The average ET-1 secretion rate for the HGMEC monolayers exposed to 0.5, 1.0, or 1.5N/m2 of shear stress was 32.83