Biomechanical study of human dura and its substitutes.

OBJECTIVE: To investigate the biomechanical characters of human dura and its substitutes and to establish guidelines for selection of optimal repair materials for reconstruction of skull base defects. METHODS: A measurement of creep properties of human dura and its substitutes were conducted using biomechanical tests. The dynamic changes of biomechanical properties of canine dura obtained from skull base defects were observed as well. RESULTS: The creep properties of human dura presented a linear-relationship between initial strain and stress, and the creep strain increased slowly with time. The creep compliance formula for human dura and its substitutes was as follows: J (t) = J(0) + Kf (t). The initial compliance of canine dura in skull base defects was reduced by 35%, 46% and 50%, respectively 1, 3 and 6 months after surgery. CONCLUSION: The optimal material for the repair of skull base defects can be estimated using creep compliance analysis. The less the compliance, the better the property of anti-protrusion. Fresh human dura is the least compliant and then in increasing order are lyophilized human dura, fresh human pericranium, Terylene and silicon membranes. The pattern of biomechanical characteristics of the dura mater at skull base defects shows that the strain ability of the dura mater decreases distinctly for 1 - 3 months and then remains almost unchanged for 3 - 6 months after surgery.

3D numerical study of tumor microenvironmental flow in response to vascular-disrupting treatments.

The effects of vascular-disrupting treatments on normalization of tumor microvasculature and its microenvironmental flow were investigated, by mathematical modeling and numerical simulation of tumor vascular-disrupting and tumor haemodynamics. Four disrupting approaches were designed according to the abnormal characteristics of tumor microvasculature compared with the normal one. The results predict that the vascular-disrupting therapies could improve tumor microenvironment, eliminate drug barrier and inhibit metastasis of tumor cells to some extent. Disrupting certain types of vessels may get better effects. In this study, the flow condition on the networks with "vascular-disrupting according to flowrate" is the best comparing with the other three groups, and disrupting vessels of lower maturity could effectively enhance fluid transport across vasculature into interstitial space.