[Comparative study on tissue morphology and vascular changes of skin xenografts, allografts and autografts after transplantation]

In this study, the tissue morphology and the vascular changes of skin xenografts from the rats to the rabbits were compared with that of skin allografts and autografts simultaneously transplanted to the same recipient by the use of histological examination and dye injection. The results suggested that the xenografts were incapable of becoming vascularized, and exhibited necrosis on the third day, while early vascularization was demonstrated in the allografts and autografts. The xenografts underwent a course of "white graft rejection", which probably contributed to rejection.

Weighted learning of bidirectional associative memories by global minimization

A weighted learning algorithm for bidirectional associative memories (BAMs) by means of global minimization, where each desired pattern is weighted, is described. According to the cost function that measures the goodness of the BAM, the learning algorithm is formulated as a global minimization problem and solved by a gradient descent rule. The learning approach guarantees not only that each desired pattern is stored as a stable state, but also that the basin of attraction is constructed as large as possible around each desired pattern. The existence of the weights, the asymptotic stability of each desired pattern and its basin of attraction, and the convergence of the proposed learning algorithm are investigated in an analytic way. A large number of computer experiments are reported to demonstrate the efficiency of the learning rule.

[Comparative study of the transplantation of vascular pedicle and traditional free tendon tissues]

The most frequent cause of failure after tendon transplantation is the formation of adhesions between the tendon graft and its surrounding tissues. In this study, the healing mechanism, adhesion formation and biomechanical properties of vascular pedicle and traditional free tendon grafts were compared in the rabbits. It was observed that the former remained normal histologically in healing process and had less adhesion formation; that of the latter underwent necrosis and was gradually replaced by new connective tissues, its adhesions were extensive and dense; and that the healing mechanism of the both tendon grafts at the anastomosed site were extrinsic, the biomechanical properties (rupture load and elastic stiffness) showed no statistically significant difference (P greater than 0.05). On the basis of these results, we believe that preserving of the blood supply of tendon graft is important for reducing the adhesion formation and improving the functional results.