Antioxidant enzyme activities and trace element concentrations in ischemia-reperfusion.

In this study, we investigated the impact of ischemia-reperfusion on antioxidant enzyme activities and trace element concentrations. For this purpose, ischemia was initiated by clamping superior mesenteric artery of Wistar (albino) rats for 30 min, followed by reperfusion for 20 min. Immediately after reperfusion, blood samples were taken and examined for red cell copper-zinc superoxide dismutase (Cu-Zn-SOD), catalase (CAT), and glutathione peroxidase (GPx) activities spectrophotometrically and plasma zinc, copper, and magnesium concentrations by atomic absorption spectrophotometer. In the ischemia-reperfusion group, red cell Cu-Zn-SOD activity and plasma zinc and copper concentrations were increased significantly (p < 0.001) when compared to the control group; however, the increases in GPx activity and plasma magnesium concentration were not significant (p > 0.05). We also found a significant (p < 0.01) decrease in catalase activity. Free radicals released as a consequence of ischemia-reperfusion caused significant alterations in antioxidant enzymes and in the concentrations of trace elements.

Does pneumoperitoneum cause bacterial translocation?

Although extensive research has been carried out on the respiratory and renal effects of intra-abdominal pressure increase, there is limited research with regard to its effects on bacterial translocation. The objective of this study was to discuss whether the high intra-abdominal pressure due to carbon dioxide (CO2) insufflation during laparoscopy leads to bacterial translocation. Eighteen male dogs, 7 of which constituted the control group, were used in the study. Two study groups, in which the intra-abdominal pressure was raised to 15 mm Hg and kept at that level for 30 and 120 minutes, respectively, were set. Blood gases and blood pressure values were observed throughout the experiments. Samples of peritoneal smear, portal vein blood, mesenteric lymph node, liver, spleen, and cecum were examined to detect bacterial translocation. Histopathological examinations of all samples were also carried out. No translocation was detected in the samples of peritoneal smear, portal blood, mesenteric lymph node, liver, or spleen, but in the samples of cecum, bacterial colonization for the second group (p<0.05) and for the third group (p<0.05) was significantly higher compared with the control group. There was a considerable difference between the second and third groups (p<0.05). The changes in the mesenteric lymph nodes were interpreted to be a result of bacterial drainage. Histopathological examination disclosed active changes in the mesenteric lymph nodes in all groups, but there was considerable sinus histiocytosis only in the third group. We conclude that the intraabdominal pressure of 15 mm Hg created by carbon dioxide insufflation does not lead to bacterial translocation but causes intraluminal bacterial colonization in the cecum after 30 minutes and after 2 hours.

Effect of haemodynamic variables on surgically created arteriovenous fistula flow.

BACKGROUND: The immediate success and flow rate of a newly constructed arteriovenous fistula is dependent on several haemodynamic factors affecting the inflow and outflow of the fistula. METHODS: In this study we evaluated the effect of preoperative arterial blood pressure, arterial inflow, subclavian venous flow, and operative venous outflow resistance on the immediate success, with special reference to the quantity of the fistula flow in 32 patients undergoing internal arteriovenous fistula operations. Flow measurements were done by utilizing colour flow duplex imaging and measurement of venous resistance of the fistula vein was accomplished indirectly by a newly developed simple system. RESULTS: A preoperative subclavian venous flow rate of less than 400 ml/min was associated with higher rate of immediate failures (P < 0.05) with a negative predictive value of 100% with 100% sensitivity. Regarding immediate failures, no other haemodynamic measurement was found to affect the success of a newly constructed fistula significantly. A linear correlation between the measured haemodynamic values and the quantity of postoperative fistula flow was not found. However, an arterial inflow value of > or = 40 ml/min was associated with higher fistula flow rates (P < 0.05). CONCLUSIONS: The immediate success and flow of a newly constructed arteriovenous fistula is mainly dependent on arterial inflow and subclavian venous flow. An arterial inflow rate of 40 ml/min or more and subclavian venous flow rate of 400 ml/min or more measured by colour flow duplex imaging prior to the operation will be associated with better outcomes, and therefore the use of colour flow duplex imaging is warranted during the evaluation of patients who are candidates for an arteriovenous fistula operation.