The evolution of a collagen/vicryl composite membrane designed as a prosthetic material for use in urinary tract surgery is described. The early experiments in which collagen film alone was used to repair experimental ureterotomies are reviewed together with our first experiments with the collagen/vicryl prosthesis in the repair of partial nephrectomies and of full thickness defects created in the urinary bladder of experimental rabbits. These early results led to the preparation of a composite using a more highly purified collagen and employing a method of sterilisation (gamma irradiation) which would be acceptable for regular use in medical products. The results of a further series of partial nephrectomy and full thickness bladder repairs show that irradiation does not compromise the efficacy of the collagen/vicryl composite in vivo.
THE failure of inalignant gliomas to give rise to extranervous mctastases poses a question which has long perplexed and fascinated pathologists. Willis (1952, p. 101), while declaring that the answer to it is speculative, directs attention to four circumstances that are worthy of consideration : (1) the absence of lymphatics in the central nervous system ; (2) the easy collapsibility of the cerebral venules ;(3) the relatively short survival of the patient ; and (4) the inability of metastatic neuroglial cells to subsist in " foreign terrains '*. I n view of Pearce and Brown's observation (1923) that their tumour of the rabbit can be transplanted successfully into the brain, as into many other organs and tissues, the following experiments were planned in the hope that they might throw some light upon the problem ; the results seem to warrant the conclusion that this particular tumour, like malignant gliomas, is unable to inetastasise from the cerebrum to extranervous tissues.
Technique of intracerebral implantationA small fragment of viable tumour was implanted deeply in the left temporal lobe of the cerebrum with a standard lumbar-puncture needle inserted through a burr-hole in the centre of the left parietal eminence of the skull. The burrhole was made with an clectric drill, uiing a bit just slightly larger in diameter than the lumbar-puncture needle. Snmthesia was obtained with intravenous nembutal supplemented by ether as required. Operative mortality was negligible.
Experiment 1Fifty-three rabbits of mixed breeds were treated in this way and tumours grew in 40 animals. Physical signs were minimal until the animals became dull and sluggish in behaviour about two days before death. Terminally, a rapidly deepening coma occurred. Pits or any form of localising sign were exceptional. The earliest death took place 16 and the latest 30 days after implantation ; the remaining animals died in 18-24 days. The tumours were remarkably uniform in their situation, though they varied moderately in size and in the extent of hsmorrhage and necrosis. A typical example is illustrated in fig. 1.
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