Polyglycolic Polymer Research Articles

The optimal diameter of microfilaments in polylactic polyglycolic polymer three-dimensional conduit in repairing peripheral nerve defects

Objective To studythe optimal diameter of microfilaments in polylactic polyglycolic polymer(PLGA)three-dimensional nerve conduit in repairing peripheral nerve defects of rats.Methods Sixty adult SD rats(weighing 300-350 g)were randomly divided into 6 groups(n=10),and their sciatic nerves(length:12 mm)were resected.In all groups except F group nerve defects were repaired using the PLGA nerve conduit containing 20 microfilaments with different diameters(60,80,100,120,and 140μm).The nerve conduits of all groups were filled with 0.3 ml laminin and never growth factor.The rats in group F were subjected to nerve autograft(control group).The left-behind legs served as experiment sides,and the right ones as control sides.To evaluate the repairing outcome,special assessments were performed including EMG testing,immunohistochemisty to test the number of regeneration nerves 12 weeks after operation.Results Twelve weeks after operation,compared to groups A and E,the conducting velocity and the weight of triceps muscle of calf were increased in groups B,C,D and F(P 0.05).Under light microscope and electron microscope,it waft,found there was significant difference in nerve fiber diameter,thickness of myelin sheath,and fiber density between groups B,C or D and groups A or C(P<0.05).Furthermore,image analysis suggested in the groups F,C,B,and D the nerve regeneration was better than in groups A and E in quantity of nerve fiber,thickness of myelin sheath,and nerve fiber diameter(P<0.05).Conclusion The diameters of microfilaments in three-dimensional nerve conduit can influence the regeneration of sciatic nerves,and the optimal diameter range is 80-120μm. Key words: Peripheral nerve; Nerve conduit; Tissue engineering

Two is better than three

Repair of the perineum after childbirth is probably the commonest operation performed today, affecting over one third of a million women each year, yet it is only recently that formal evaluation of this procedure has been carried out. We now know from randomised trials that absorbable sutures are preferred to non-absorbable sutures, that polyglycolic acid is preferred to catgut, and that continuous sutures to the perineal skin are preferred to interrupted ones. But are sutures to the perineal skin required at all? This question has been answered by Beverly Gordon and Carolyn Mackrodt and their colleagues (pages 435440; pages 441–445) in the Ipswich Childbirth Study. This was a stratified randomised trial with a factorial design to test two hypotheses: that perineal repair in two layers and not three, omitting the skin, would result in no increase in perineal pain; and that a new polyglycolic polymer, polyglactin 910, would also result in no increase in perineal pain. The authors enrolled 1780 women who had sustained a perineal tear or episiotomy, following a spontaneous delivery or outlet operative delivery. The study is a model in the conduct of a randomised trial: the hypotheses being tested were clearly stated, with an estimation of the size of trial required based on these hypotheses; the type of randomisation was specified, with a description of the concealment of the allocations until the point of treatment; the tables of the characteristics of the women participating in the trial gave sufficient information to reassure us that the random allocation was successful in producing two groups of women who were similar as regards important prognostic variables; as far as possible ascertainment of the out- comes was performed in ignorance of the treatment given; and the follow-up was rigorous, with information being available from more than nine-tenths of the women at three months. And the results are quite clear. Leaving the perineal skin unsutured does not increase pain in the first ten days, and fewer women reported that their stitches felt tight; fewer women experienced pain at three months, more had resumed intercourse, and fewer had dyspareunia; and fewer women required removal of suture material. Suturing the perineum with polyglactin 910 resulted in less pain in the first ten days; but a greater need to remove suture material. These results suggest that in perineal repair the skin should not be sutured, and that polyglactin 910 is preferable to catgut (perhaps the tendency of polyglactin 910 sutures to require removal can be offset by not suturing the skin. The next step is to investigate not suturing the perineum at all in women with small episiotomies or perineal tears who do not have disruption of the anal sphincter.