Porcine small intestine submucosa as a flexor tendon graft

An attractive strategy for tendon tissue engineering is the use of natural extracellular matrices as scaffold materials. One matrix that has been shown to promote healing and regeneration of neotissue in various applications is porcine-derived small intestinal submucosa. It was the objective of this study to investigate small intestinal submucosa for intrasynovial flexor tendon grafting in a canine model. We hypothesized that at 6 weeks small intestinal submucosa grafts would undergo host cell infiltration, neovascularization, and replacement by host neotendon. We also hypothesized that small intestinal submucosa grafts would be incorporated by the host without extensive adhesions to surrounding tissues and therefore maintain normal digit function. An intrasynovial tendon autograft was used as a gold standard. At 6 weeks the intrasynovial tendon autografts remained viable, contained normal numbers of cells along their length, and had minimal peritendinous adhesions. Four of six autografts had normal function as determined by rotation of the distal interphalangeal joint. Also at 6 weeks, the small intestinal submucosa grafts had host cell infiltration, neovascularization, and wavy, oriented tissue. However, ubiquitous adhesions together with impaired function in all cases suggest that small intestinal submucosa grafts in the configuration used are not suitable as full-length intrasynovial grafts in this tendon and animal model.

Tumour necrosis factor does not increase during routine cuprophane haemodialysis in healthy well-nourished patients

Serum tumour necrosis factor (TNF) was measured by both bioassay and immunoassay (ELISA) during routine cuprophane acetate haemodialysis in 17 asymptomatic patients. In 14 (82%) there was no change in the serum values during haemodialysis. TNF was found to increase, using both assays, in three patients, the responders. These patients differed from the others in terms of body mass index, mean index 16.8 kg/m2 (range 14.8-18.2), compared to the non-responders, mean 24.1 kg/m2 (range 19.6-33.1), P less than 0.05, and had an increased serum calcium, mean 2.9 mmol/l (range 2.6-3.2) compared to the non-responders, mean 2.4 mmol/l (range 1.7-2.8), P less than 0.05. Two of the TNF responders subsequently died of cachexia and respiratory infection. The third underwent a successful parathyroidectomy, and when retested after an increase in body-weight with a normal serum calcium concentration no longer showed an increase in TNF during haemodialysis.