Background: Balloon injury (BI) of the rat carotid artery (CCA) is widely used to study intimal hyperplasia (IH) and decrease in lumen diameter (LD), but CCA's small diameter impedes the evaluation of endovascular therapies. Therefore, we validated BI in the aorta (AA) and iliac artery (CIA) to compare it with CCA.

Background and Objectives: Previous studies with PhotoDynamic Therapy (PDT) in bladder and bronchi have shown that due to scattering and reflection, the actually delivered fluence rate on the surface in a hollow organ can be significantly higher than expected. In this pilot study, we investigated the differences between the primary calculated and the actual measured fluence rate during PDT of Barrett's Esophagus (BE) using 23 independent clinical measurements in 15 patients. Study Design/Materials and Methods: A KTP-dye module laser at 630 nm was used as light source. Light delivery was performed using a cylindrical light diffuser inserted in the center of an inflatable transparent balloon with a length corresponding to the length of the Barrett's epithelium. The total light output power of the cylindrical diffuser was calibrated using an integrating sphere to deliver a primary fluence rate of 100 mW cm À2 . Two fiber-optic pseudo sphere isotropic detectors were placed on the balloon and were used to measure fluence rate at the surface of the esophageal wall during PDT. Results and Conclusions: The actual fluence rate measured was 1.5-3.9 times higher than the primary fluence rate for 630 nm. In general, the fluence rate amplification factor decreased with increasing redness of the tissue and was less for shorter diffusers. Fluence rate variations in time were observed which coincided with patients coughing, movement, and esophageal spasms. These factors combined with inter patient variability of the fluence rate measured appears to justify the routine application of this technique in PDT of BE.

Background: Temporary vascular inflow occlusion of the liver (clamping of the hepatic pedicle) can prevent massive blood loss during liver resections. In this study, intrahepatic tissue pO₂ was assessed as parameter of microcirculatory disturbances induced by ischemia and reperfusion (I/R) in the liver following continuous (Cnt) or intermittent (Int) clamping in a hemihepatectomy model in the pig. Methods: Pigs (20–34 kg) were divided into 2 groups: I/R without hemihepatectomy (–HH; n = 10) and I/R with hemihepatectomy (+HH; n = 8). Ischemia during 90 min was Cnt or Int (6 sequential periods of 12 min of ischemia and 3 min of reperfusion), followed by 120 min of reperfusion. Intrahepatic pO₂ histograms (polarographic pO₂ needle electrode) were constructed before ischemia, at the end of 90 min of ischemia and after 120 min of reperfusion, along with assessment of plasma AST, ALT and LDH. Bile production was monitored continuously. Results: Cumulative frequency distribution curves (CFDC) after 120 min of reperfusion in the Cnt–HH group were not different from preischemic CFDC (means ± SEM), whereas in the Int–HH group a left shift occurred indicating more hypo(non)perfused liver areas (pO₂ < 10 mm Hg: 2.6 ± 1.2 and 41.0 ± 17.5% in Cnt–HH and Int–HH; p < 0.01). In the Cnt+HH group, a left shift in the CFDC occurred. In the Int+HH group, a left and a right shift occurred simultaneously, indicating both hypo(non)- and hyperperfused (shunting) liver areas (pO₂ < 10 mm Hg: 4.0 ± 2.7 and 9.6 ± 8.5%, n.s., and pO₂ > 60 mm Hg: 2.0 ± 2.0 and 17.3 ± 6.4%, p = 0.015, in Cnt+HH and Int+HH). Plasma AST, ALT and LDH levels were not increased after 120 min of reperfusion, except for AST in Cnt+HH and Int+HH (from 54.6 ± 14.0 to 270.4 ± 42.8 U/l, p < 0.01, and from 47.8 ± 9.4 to 176.5 ± 55.9 U/l, n.s.). Bile production (percentage of mean preischemic value) during 120 min of reperfusion was significantly reduced in the Int–HH group, as compared to the Cnt–HH group (57.0 and 117.0% after 120 min of reperfusion, p = 0.002). In Cnt+HH and Int+HH, bile production was significantly reduced (33.3 ± 20.0%, p = 0.05, and 38.5 ± 7.9%, p = 0.007); however it was not different between the two groups. Conclusions: (1) Intrahepatic tissue pO₂ as indicator of microvascular perfusion is a parameter of early I/R injury; (2) continuous vascular inflow occlusion resulted in less microcirculatory disturbances, when compared to intermittent occlusion.