Ischemia In Vivo Induces Cardiolipin Oxidation in Rat Kidney Mitochondria

Cardiolipin is a mitochondrial phospholipid that plays a significant role in mitochondrial bioenergetics. Cardiolipin is oxidized under conditions like oxidative stress that occurs during ischemia/reperfusion; however, it is known that even during ischemia, many reactive oxygen species are generated. Our aim was to analyze the effect of in vivo ischemia on cardiolipin oxidation. Adult male Wistar rats were anesthetized; then, their abdomens were opened, and microvascular clips were placed on renal arteries for 30, 40 or 60 min, causing ischemia. After ischemia, kidneys were harvested, mitochondria were isolated, and lipids were extracted for chromatographic and mass spectrometric analysis of tetralinoleoyl cardiolipin and its oxidation products. Chromatographic and mass spectrometric analysis revealed a 47%, 68% and 74% decrease in tetralinoleoyl cardiolipin after 30 min, 40 min and 60 min of renal ischemia, respectively (p < 0.05). Eight different cardiolipin oxidation products with up to eight additional oxygens were identified in rat kidney mitochondria. A total of 40 min of ischemia caused an average of a 6.9-fold increase in all oxidized cardiolipin forms. We present evidence that renal ischemia in vivo alone induces tetralinoleoyl cardiolipin oxidation and depletion in rat kidney mitochondria

Surgical site infections in cardiac surgery: risk factors, microbiological characteristics of causative pathogens

Aims: the aim of this study is to analyze the risk factors, the range of causative pathogens and their resistance to antibiotics in surgical site infections (SSIs) following coronary artery bypass surgeries. Objectives: 1. To calculate the incidence of SSIs following coronary artery bypass surgeries. 2. To determine risk factors for SSIs. 3. To evaluate the range of causative pathogens and their sensitivity to antibiotics. Methodology. This study involved a group of patients that underwent coronary artery bypass surgery between August and December of 2014 and between August and December of 2017. The surgeries were performed in the hospital of Lithuanian University of Health Sciences “Kauno Klinikos” (LUHS KK), department of cardiac surgery. A retrospective analysis was performed on the patients’ medical history records and microbiological test results. All data was gathered in a special surgical site infection surveillance data collection form approved by the Minister of Health of the Republic of Lithuania (annex 1). The data was then entered and coded in an electronic database of digital forms created with EpiData Entry 3.1 application (annex 2). All data was analyzed using Microsoft Office Excel and IBM SPSS Statistics 23.0. Mann-Whitney U test was used to compare the means of two independent samples, ANOVA F test was used to compare the means of three or more independent samples. Pearson correlation was used to analyze the linear relationship between two continuous variables. Chi-square (χ2) test was used to analyze the relationship between categorical variables. The difference between samples was considered to be statistically significant when p ≤ 0,05. Results. The study included data of 479 patients: 333 men (69,5 %) and 146 women (30,5 %). The mean age was 68,1 ± 9,19 years, with a median of 69 years. 320 (66,8 %) of the patients did not have any of the risk factors, 39 (8,1 %) patients had diabetes, 92 (19,2 %) patients were obese (BMI > 30), and 28 (5,8 %) were obese and had diabetes. The mean length of hospital stay was 21,3 ± 11,95 days. Most of the coronary artery bypass surgeries were performed using three or four and more grafts, respectively 200 (41,8 %) and 208 (43,4 %) cases, the mean duration of all performed surgeries was 206,24 ± 53,42 minutes. There were 343 (71,6 %) patients with ASA score of 3, 135 (28,2 %) patients with ASA score of 4 and only one (0,2 %) with ASA score of 5. 476 (99,4 %) patients were administered antibiotic prophylaxis. A total of 37 patients (7,7 %) developed SSIs, seven of them were caused by Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa and Serratia marcescens. The latter (S. marcescens) was resistant to ampicillin, ampicillin/sulbactam, cefuroxime, cefotaxime and ciprofloxacin. Conclusions. The overall incidence of SSIs following coronary artery bypass surgeries in the hospital of LUHS KK, department of cardiac surgery, was 7,7 %. No significant risk factors for SSIs were identified in this study. Male sex and longer duration of surgery were factors that could have had little significance for SSIs development in patients. Seven microorganisms were isolated, four of them were methicillin-sensitive S. aureus. Other isolated microorganisms were E. faecalis, P. aeruginosa and S. marcescens, which was resistant to ampicillin, ampicillin/sulbactam, cefuroxime, cefotaxime and ciprofloxacin

Increased Succinate Accumulation Induces ROS Generation in In Vivo Ischemia/Reperfusion-Affected Rat Kidney Mitochondria

Mitochondria are recognized as main reactive oxygen species (ROS) producers, involving ROS generation by mitochondrial complexes I and III. Lately, the focus has been shifting to the ROS generation by complex II. Contribution of complex II (SDH) to ROS generation still remains debatable, especially in in vivo settings. Moreover, it is not completely defined at what time of ischemia the first alterations in mitochondria and the cell begin, which is especially important with renal arterial clamping in vivo during kidney surgery, as it predicts the postischemic kidney function. The aim of this study on an in vivo rat kidney ischemia/reperfusion model was to determine if there is a connection among (a) duration of kidney ischemia and mitochondrial dysfunction and (b) succinate dehydrogenase activity, succinate accumulation, and ROS generation in mitochondria at low and saturating succinate concentrations. Our results point out that (1) mitochondrial disturbances can occur even after 30 min of kidney ischemia/reperfusion in vivo and increase progressively with the prolonged time of ischemia; (2) accumulation of succinate in cytosol after ischemia/reperfusion correlated with increased H2O2 generation mediated by complex II, which was most noticeable with physiological succinate concentrations; and (3) ischemia/reperfusion induced cell necrosis, indicated by the changes in LDH activity. In conclusion, our new findings on the accumulation of succinate in cytosol and changes in SDH activity during kidney ischemia/reperfusion may be important for energy production after reperfusion, when complex I activity is suppressed. On the other hand, an increased activity of succinate dehydrogenase is associated with the increased ROS generation, especially with physiological succinate concentrations. All these observations play an important role in understanding the mechanisms which occur in the early phase of ischemia/reperfusion injury in vivo and may provide [...]

In Vitro Hypoxia/Reoxygenation Induces Mitochondrial Cardiolipin Remodeling in Human Kidney Cells

Renal ischemia/reperfusion is a serious condition that not only causes acute kidney injury, a severe clinical syndrome with high mortality, but is also an inevitable part of kidney transplantation or other kidney surgeries. Alterations of oxygen levels during ischemia/reperfusion, namely hypoxia/reoxygenation, disrupt mitochondrial metabolism and induce structural changes that lead to cell death. A signature mitochondrial phospholipid, cardiolipin, with many vital roles in mitochondrial homeostasis, is one of the key players in hypoxia/reoxygenation-induced mitochondrial damage. In this study, we analyze the effect of hypoxia/reoxygenation on human renal proximal tubule epithelial cell (RPTEC) cardiolipins, as well as their metabolism and mitochondrial functions. RPTEC cells were placed in a hypoxic chamber with a 2% oxygen atmosphere for 24 h to induce hypoxia; then, they were replaced back into regular growth conditions for 24 h of reoxygenation. Surprisingly, after 24 h, hypoxia cardiolipin levels substantially increased and remained higher than control levels after 24 h of reoxygenation. This was explained by significantly elevated levels of cardiolipin synthase and lysocardiolipin acyltransferase 1 (LCLAT1) gene expression and protein levels. Meanwhile, hypoxia/reoxygenation decreased ADP-dependent mitochondrial respiration rates and oxidative phosphorylation capacity and increased reactive oxygen species generation. Our findings suggest that hypoxia/reoxygenation induces cardiolipin remodeling in response to reduced mitochondrial oxidative phosphorylation in a way that protects mitochondrial function