In Vitro Evaluation of a Novel Synthetic Bilirubin Analog as an Antioxidant and Cytoprotective Agent for Pancreatic Islet Transplantation.

Bilirubin is a natural cytoprotective agent and physiologic doses have proven to be beneficial in various models of organ and cellular transplantation. Recently, we showed that bilirubin has protective effects in models of pancreatic islet transplantation, preventing cell death associated with islet stress and suppressing the release of damage-associated molecular patterns. Despite these promising therapeutic attributes, the natural bilirubin used in these research studies is animal-derived (porcine), making it unsuitable for clinical application. In the current study, we synthesized two bilirubin analogs that can be produced without the use of animal-derived products. Antioxidant activity for the analogs was measured using the ferric-reducing-ability-of-plasma (FRAP) and 2,2V-azinobis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) assays. Dose-dependent cytotoxicity and cytoprotective effects were then demonstrated in isolated rat islets. Compound 1 showed similar antioxidant activity to natural bilirubin. Dose-dependent cytotoxicity was seen following treatment with Compound 1 and natural bilirubin at doses >40 µM, resulting in significantly increased cell death when compared to control islets (P < 0.05) or islets treated with doses ≤20 µM (P < 0.05). Following hypoxic challenge, islet cell death was reduced in islets treated with Compound 1 at 10 µM (17.27% ± 0.26%) compared to natural bilirubin at 10 µM (51.36% ± 0.71%; P < 0.0001) or 20 µM (59.02% ± 0.83%; P < 0.0001) and control islets (36.51% ± 0.44%; P < 0.0001). Compound 1 was found to have promising antioxidant and cytoprotective effects, limiting islet cell death in a model of islet transplantation hypoxic stress. Compound 1 may serve as a synthetic drug lead for clinical islet transplantation and further evaluation of this molecule and its analogs is warranted.

Laparoscopic placement and urodynamic effects of an artificial urethral sphincter in cadaveric dogs.

OBJECTIVE: To describe a laparoscopic approach for placement of a percutaneously controlled artificial urethral sphincter (AUS) in female cadaver dogs and compare the change in urethral pressure and lumen diameter after filling the device. STUDY DESIGN: Experimental study. ANIMALS: Canine female cadavers (n = 10). METHODS: A laparoscopic technique was used to implant the AUS in 10 cadaver dogs. Maximum urethral closure pressure (MUCP), cystourethral leak point pressure (CLPP), and urethral luminal area were measured at 0, 25, 50, and 75% cuff inflation. Necropsy was performed after urethral pressure profilometry and cystoscopy data collection to assess for trauma caused by the procedure. RESULTS: Laparoscopic implantation was performed successfully in all 10 cadavers with no evidence of inadvertent trauma. Median MUCP at 0% AUS fill (48.9 cmH2 O) was significantly lower than 75% fill (243.5 cmH2 O). Median CLPP at 0% fill (5.0 cmH2 O) was significantly lower than 75% fill (23.2 cmH2 O). Significant differences were also found comparing urodynamic values 25 to 50%, 25 to 75%, and 50 to 75%. Cystoscopic evaluation revealed progressive decreases in urethral lumen area and significant differences between the urethral luminal area values as the AUS cuff was inflated. CONCLUSION: Laparoscopic placement of an AUS can be performed successfully in cadaver dogs, improved urethral pressure profile parameters, and visibly occluded the urethral lumen. Further studies of laparoscopic placement in clinical cases affected by urethral sphincter mechanism incompetence are warranted.