A multi-body model for comparative study of cervical traction simulation - comparison between inclined and sitting traction.

A computer simulation model was developed to compare the result of cervical traction therapy in inclined and sitting traction positions. The behavior of the model was shown to match with the intervertebral changes in the upper and lower spine from the data of a radiographic experiment. Both the results of the experiment and the simulation also showed that in the inclined position, the amount of posterior separations in the upper cervical spine remains constant regardless of traction angle, while the posterior separations at lower cervical spine increases along with traction angles. Using the simulation model, parametric studies were conducted to investigate the intervertebral space changes in response to different traction angles in the inclined and sitting positions. When using the sitting position, the subject's hip joint stiffness was shown to cause larger variations in the intervertebral space than in the inclined position. In addition, variations in the tension/compression stiffness was shown to cause the largest changes in the resulting separations in both positions but the variations in anterior space changes were larger in the sitting position. Our study suggests that the inclined position is less sensitive to variations in the subject's body parameters and is able to provide a more reliable and predictable traction result than the sitting position.

A multi-body model for comparative study of cervical traction simulation - development, improvement and validation.

A computer simulation model was developed to study the dynamic behavior of the cervical spine during cervical traction therapy in inclined and sitting traction positions. The model improved upon an old model with additional components to represent the behavior of the intervertebral discs and the posterior ligaments. The simulation result of the new model was compared against the cervical traction data from a radiographic experiment in both positions. The simulation results of the old model and new model were compared to illustrate the improvement. Using the new model, we compared the timing response of cervical traction in the inclined and sitting positions.

Squalene synthase inhibitors suppress triglyceride biosynthesis through the farnesol pathway in rat hepatocytes.

We recently demonstrated that squalene synthase (SQS) inhibitors reduce plasma triglyceride through an LDL receptor-independent mechanism in Watanabe heritable hyperlipidemic rabbits (Hiyoshi et al. 2001. Eur. J. Pharmacol. 431: 345-352). The present study deals with the mechanism of the inhibition of triglyceride biosynthesis by the SQS inhibitors ER-27856 and RPR-107393 in rat primary cultured hepatocytes. Atorvastatin, an HMG-CoA reductase inhibitor, had no effect on triglyceride biosynthesis, but reversed the inhibitory effect of the SQS inhibitors. A squalene epoxidase inhibitor, NB-598, affected neither triglyceride biosynthesis nor its inhibition by ER-27856 and RPR-107393. The reduction of triglyceride biosynthesis by ER-27856 and RPR-107393 was potentiated by mevalonolactone supplementation. Treatment of hepatocytes with farnesol and its derivatives reduced triglyceride biosynthesis. In addition, we found that ER-27856 and RPR-107393 significantly reduced the incorporation of [1-(14)C]acetic acid into oleic acid, but not the incorporation of [1-(14)C]oleic acid into triglyceride. Though ER-27856 and RPR-107393 increased mitochondrial fatty acid beta-oxidation, the inhibition of beta-oxidation by RS-etomoxir had little effect on their inhibition of triglyceride biosynthesis. These results suggest that SQS inhibitors reduce triglyceride biosynthesis by suppressing fatty acid biosynthesis via an increase in intracellular farnesol and its derivatives.