Non-linear material models for tracheal smooth muscle tissue.

The aim of this study is to investigate the hyperelastic material models to describe the non-linear stress-strain behavior of tracheal smooth muscle tissue. Specifically, the goal is to validate the material model with experimental data using different finite element models and discuss the trends in stress-strain behavior of smooth muscle tissue. Both 2D and 3D finite element analyses were carried out to estimate the stress-strain behavior of the smooth muscle tissue. The results obtained indicate that the developed Ogden material model is valid and useful in explaining the stress strain behavior of tracheal smooth muscle tissue under different conditions. Finite element simulation results of the stress-strain behavior in the transverse direction are presented.

Anisotropic properties of tracheal smooth muscle tissue.

The anisotropic (directional-dependent) properties of contracting tracheal smooth muscle tissue are estimated from a computational model based on the experimental data of length-dependent stiffness. The area changes are obtained at different muscle lengths from experiments in which stimulated muscle undergoes unrestricted shortening. Then, through an interative process, the anisotropic properties are estimated by matching the area changes obtained from the finite element analysis to those derived from the experiments. The results obtained indicate that the anisotropy ratio (longitudinal stiffness to transverse stiffness) is about 4 when the smooth muscle undergoes 70% strain shortening, indicating that the transverse stiffness reduces as the longitudinal stiffness increases. It was found through a sensitivity analysis from the simulation model that the longitudinal stiffness and the in-plane shear modulus are not very sensitive as compared to major Poisson's ratio to the area changes of the muscle tissue.

Total cholesterol concentration in relation to superovulatory responses in crossbred cows.

Blood serum total cholesterol levels of crossbred Taur-indicus donor cows (n=22), in their 1st to 4th parity, were studied as an indicator of embryo yield. These cows were superovulated either with FSH or PMSG + anti-PMSG on the 12th day of the synchronized estrous cycle. The total and transferable number of embryos did not differ significantly between the treatment groups. The number of corpora lutea and total and transferable embryos in donors having total cholesterol levels <140 mg/dl were significantly (P < 0.05) lower than those of cows having >140 mg/dl, indicating that low total cholesterol levels might adversely affect superovulatory response. Thus, estimation of total cholesterol concentrations of potential donors can be a useful tool for predicting superovulatory responses.