PROTECTIVE EFFECT OF RIBCYS FOLLOWING HIGH-DOSE IRRADIATION OF THE RECTOSIGMOID

Ribose-cysteine (RibCys) is a prodrug of L-cysteine that stimulates gl utathione biosynthesis. Increased glutathione levels have been shown t o have a protective effect against radiation-induced injury and oxidat ive stress. Surface oximetry has previously been used successfully to predict anastomotic leakage. PURPOSE: The following study was done to evaluate the protective effect of RibCys and the predictive value of P tO2 determinations in a swine model. METHODS: Domestic swine were divi ded into three groups: Group A served as a nonradiated control; Group B received 6,000 to 6,500 rad to the rectosigmoid; and Group C receive d RibCys (1 g/kg) prior to receiving 6,000 to 6,500 rad. Radiated anim als and controls underwent rectosigmoid resection after a three-week r est period. Intraoperative anastomotic PtO2 was checked with a modifie d Clark electrode. Anastomoses were evaluated radiographically at thre e and seven days; animals were sacrificed, and bursting strength was r ecorded at 10 days. RESULTS: Mean bursting pressures were 243.8 +/- 59 .4, 199.5 +/- 37.8, and 209.5 +/- 54.9 mmHg (NS) for Groups A, B, and C, respectively. Anastomotic PtO2 ranged from 19 to 98 mmHg and could not be correlated with anastomotic leaks or bursting pressure. There w ere 11/15 radiation-related deaths and leaks (eight deaths and three l eaks) in the radiated group and 4/12 radiation-related deaths and leak s (three deaths and one leak) in the group receiving radiation and Rib Cys (P < 0.04). CONCLUSIONS: 1) RibCys protected animals against radia tion-related deaths and anastomotic leaks- following high doses of pel vic irradiation; 2) anastomotic PtO2 levels did not correlate with ana stomotic healing in this model.