Tracheal anastomoses are, even more so than other sutures, often only possible to prepare under tension and thus in danger of breakage. No information is available regarding native tracheae and freshly sutured tracheae. For this reason, our objective was to examine the tensile strength of native tracheae and compare it with freshly sutured specimens. Fresh tracheae were collected from the local slaughterhouse within 30 min of slaughter. With the help of a suitable holding device, 24 fresh tracheae were mounted on a material testing machine and stretched to breaking point, during which the force and distance required were recorded. The same study was carried out on each 10 freshly anastomosed tracheae using three different suturing techniques. The mean value of the maximum force required for native tracheae was 198 N. With continuous suturing (polypropylene), a mean value of 171 N was attained, and with single interrupted suturing (polydioxanone and polyglactin 910), 123 N, respectively, 108 N. Differences between the groups proved to be highly significant. With respect to the mechanical strain from traction, the continuous suture proved to be statistically identical to native tracheae, whereas single interrupted sutures revealed a considerably lower stability under burden. Therefore, the continuous suture is of advantage in respect of the mechanical strain from traction and the suture protection of tracheal anastomoses. Further studies with differing survival times in vivo with this method provide insight into the stability of tracheal anastomoses during the healing process.
We have constructed a bioreactor aimed at imitating the three-dimensional micro- and macroenvironment of the liver. In vivo hepatocytes are arranged in plates of cell monolayers and are specifically attached with both sinusoidal surfaces to the space of Disse which contains extracellular matrix. Nonparenchymal cells are located on the other side of the space of Disse toward the sinusoid. For supporting monolayer hepatocytes with bipolar attachment to the extracellular matrix, we used a double gel culture technique that sandwiches hepatocytes between two layers of collagen. In double gel cultures, albumin production increases during an adaptive period to the in vitro environment. In contrast to conventional single gel hepatocytes, double gel hepatocytes maintain expression of sinusoidal microvilli and a polyhedric cell shape in culture as seen by transmission electron microscopy. Albumin production in the bioreactor was stable. The organotypical bioreactor concept is an example of organ mimicry and may provide the basis for the organ-otypical development of a full-sized hybrid artificial liver.
In conclusion, in this ex vivo model of discordant xenotransplantation, rhAT reduced XAH and prevented TMA in doses that appear feasible for use in clinical or preclinical transplantation settings.
After 14 days, when a bronchial stump is considered to be healed, the resistance to pressure of a mechanical suture is equal to that of the manual suture.
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