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.

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

Objective: To develop an on-line system for the measurement of blood viscosity and hematocrit. The dynamic changes of the macrovascular blood volumes, microvascular blood volumes and the total blood volume were observed by means of calculating from the testing result. Methods: Applying traditional viscosity measurement principle and specif ic wavelength optic density measurement method, an on-line system for the measurement of blood viscosity and hematocrit was developed, and the APD multifunctional board and the testing circuit were designed by ourselves. The system was validated by experiments both in vitro and in vivo. Therapeutic effects of hypertonic saline dextran solution (HSD) and Lactatic Ringerps solution at the early stage after burn-blast combined injury were compared by this method. Results: The results showed that the system has attained the goal of the design. The changes of the blood viscosity and hematocrit could be detected effectively and continuously. The changes of macrovascular, microvascular and total blood volume could be calculated approximately. Conclusions: The system and the method can continuously on-line test the blood viscosity and hematocrit, and reveal the change and distribution of blood volumes more accurately and clearly in the therapy process by estimating changes of the macrovascular, microvascular and total blood volumes, respectively. It has conf irmed that HSD treatment could increase blood pressure and attenuate tissue edema by signif icantly increasing total blood volume, improving macrocirculatory and microcirculatory blood volumes. This study suggested that it could be desirable to develop an experiment technique based on the method mentioned above.

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.

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.