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Postconditioning (PostC) can be obtained either with brief cycles of ischemia/reperfusion (I-PostC) or with a direct targeting of mitochondria with Diazoxide (pharmacological PostC, P-PostC). I-PostC may induce the activation of RISK and SAFE pathways and may favor nitric oxide production with S-Nitrosylation of proteins and redox signaling. It is not clear whether Diazoxide can lead to similar effects. We compared the effects of I-PostC and P-PostC on (a) kinases of RISK- and SAFE pathway, (b) S-Nitrosylation of mitochondrial proteins and (c) reduction of death signals (PKCδ, cleaved caspase-3 and Beclin-1) in cytosolic and mitochondrial fractions. Isolated rat hearts underwent (1) perfusion without ischemia (Sham), (2) ischemia/reperfusion (30-min ischemia plus 2-h reperfusion), (3) I-PostC (5 intermittent cycles of 10-s reperfusion and 10-s ischemia immediately after the 30-min ischemia), (4) P-PostC (Diazoxide 30 μM in the first of 3-min of reperfusion) or (5) I-PostC + MPG or P-PostC + MPG (MPG, 2-mercaptopropionylglycine 300 μM). Using Western blot and biotin switch assay, we found that P-PostC induced a redox sensible phosphorylation/translocation of Akt, ERK1/2 and GSK3β into the mitochondria, but not of phospho-STAT3, which was translocated into the mitochondria by I-PostC only. Either I-PostC or P-PostC increased mitochondrial S-Nitrosylated proteins (e.g., VDAC) and reduced the levels of phospho-PKCδ, cleaved caspase-3 and Beclin-1. Therefore, direct targeting of mitochondria with Diazoxide (a) activates the RISK pathway via a redox signaling, (b) favors discrete mitochondrial protein S-Nitrosylation, including VDAC and (c) decreases signals of death. Intriguingly, phospho-STAT3 translocation is induced by I-PostC, but not by P-PostC, thus suggesting a redox-independent mechanism in the SAFE pathway.

We hypothesized that nandrolone (ND)-abuse induces cardiac hypertrophy, increases myocardial susceptibility to ischemia/reperfusion (I/R) injury, and reduces responsiveness to postconditioning (PostC) cardioprotection. Wistar-rats were ND treated for 2 weeks (short_ND) or 10 weeks (long_ND). Vehicle-treated rats served as controls. Hearts were retrogradely perfused and left ventricular pressure (LVP) was measured before and after 30-min global ischemia. In subgroups of hearts, to induce cardioprotection a PostC protocol (five cycles of 10-s reperfusion and 10-s ischemia) was performed. β-adrenoreceptors, kinases (Akt and GSK-3β) and phosphatases (PP2A sub A and PP2A sub B) were examined by Western blot before and after ischemia. After 120-min reperfusion, infarct size was measured. Short_ND slightly increased cardiac/body weight ratio, but did not affect cardiac baseline nor post-ischemic contractile function or infarct size when compared to vehicle hearts. However, PostC limited cardiac dysfunction much more in short_ND hearts than the other groups. Although cardiac/body weight ratio markedly increased after long_ND, baseline LVP was not affected. Yet, post-ischemic contracture and infarct size were exacerbated and PostC was unable to reduce infarct size and ventricular dysfunction. While short_ND increased phosphatases, non-phosphorylated and phosphorylated Akt, long_ND reduced phosphatase-expression and Akt phosphorylation. Both short_ND and long_ND had no effect on the GSK-3β-phosphorylation but increased the expression of β 2 -adrenoreceptors. In reperfusion, PostC increased Akt phosphorylation regardless of protective effects, but reduced phosphatase-expression in protected hearts only. In conclusion, short_ND improves post-ischemic myocardial performance in postconditioned hearts. However, long_ND increases myocardial susceptibility to I/R injury and abolishes cardioprotection by PostC. This increased susceptibility might be related to steroid-induced hypertrophy and/or to altered enzyme expression/phosphorylation.

Background/aim:Endotoxaemia can complicate hepatic ischaemia–reperfusion (IR) injury. Endocannabinoids appear to modulate the haemodynamic alterations and cytokine response induced by lipopolysaccharide (LPS). Thus, we aimed to determine the effect of the endocannabinoid CB1-receptor antagonist Rimonabant in a model of hepatic IR injury complicated by endotoxaemia.Methods:Sprague–Dawley rats pre-treated with Rimonabant 3 or 10 mg/kg or vehicle underwent partial hepatic IR and lipopolysaccharide (LPS) injection at reperfusion. Liver injury was evaluated by serum alanine aminotransferase (ALT) and necrotic-cell count. The inflammatory response was investigated by assessing hepatic neutrophil infiltration, tumour necrosis factor α (TNFα), interferon γ (IFNγ), interleukin 6 (IL6), and suppressor of cytokine signalling (SOCS) 1 and SOCS3 gene expression by real-time polymerase chain reaction (RT-PCR). Systolic blood pressure and hepatic blood flow were measured as haemodynamic parameters. Finally, lipid peroxidation, glutathione status, and immunoreactive CB1 receptor expression in the liver were also determined.Results:Liver injury and neutrophil infiltration occurring in the late-phase of LPS-enhanced IR were significantly reduced by CB1-receptor antagonism. Rimonabant-treated rats showed significantly higher gene expression of IFNγ, IL6, SOCS1 and SOCS3 in “early” reperfusion, while that of TNFα was reduced. These findings were associated with increased STAT3 phosphorylation. Furthermore, CB1-receptor antagonism significantly improved the oxidative injury and haemodynamic alterations occurring during reperfusion in untreated rats. Finally, CB1-receptor immunoreactivity was upregulated early after reperfusion.Conclusions:This study demonstrates that CB1-receptor antagonism protects the liver against LPS-enhanced IR injury by interfering with the inflammatory response that causes the late, neutrophil-dependent phase of reperfusion injury, although the prevention of the transient endotoxin-related hypotension occurring early during reperfusion may be also involved.

Oxidative stress and kidney dysfunction due to ischemia/reperfusion in rat: Attenuation by dehydroepiandrosterone. The pathogenesis of ischemia/reperfusion (I/R) involves generation of reactive oxygen and nitrogen species. This in vivo study investigates the effect of dehydroepiandrosterone (DHEA), a physiologic steroid with antioxidant properties, on oxidative balance and renal dysfunctions induced by monolateral I/R. Normal and DHEA-treated rats (4mg/day × 21 days, orally) were subjected to monolateral renal I/R (30 minutes/6 hours). The oxidative state was determined by measuring hydrogen peroxide level and activities of glutathione-peroxidase, catalase, and superoxide dismutase. Tumor necrosis factor-α (TNF-α) and nitric oxide production and inducible nitric oxide synthase (iNOS) levels were also measured. Hydroxynonenal content was used to probe lipid peroxidation. Functional parameters determined were creatinine levels and Na/K-ATPase activity. Immunohistochemical and morphologic studies were also performed. A markedly pro-oxidant state was evident in the kidney of rats subjected to I/R. Both hydrogen peroxide and reactive nitrogen species (nitric oxide and iNOS) increased, whereas antioxidants decreased. Oxidant species induce TNF-α increase, which, in turn, produces lipoperoxidative processes, as documented by the increased hydroxynonenal (HNE) level. As final result, impaired renal functionality, hydropic degeneration, and vacuolization of proximal convolute tubules were observed in kidneys of I/R rats. DHEA pretreatment improved the parameters considered. I/R induces oxidative stress and consequently damages the proximal convolute renal tubules. Rats supplemented with DHEA and subjected to I/R had reduced pro-oxidant state, oxidative damage, and improved renal functionality, indicating an attenuation of oxidative injury and dysfunctions mediated by I/R.

Since children with chronic diseases represent a primary target for immunization strategies, it is important that their immunization coverage and timeliness of vaccines is optimal. We performed a study to measure immunization coverage and timeliness of vaccines in children with type 1 diabetes, HIV infection, Down syndrome, cystic fibrosis, and neurological diseases. A total of 275 children aged 6 months–18 years were included in the study. Coverage for diphtheria–tetanus–pertussis (DTP), polio (Pol), and hepatitis B (HBV) vaccines approximated 85% at 24 months, while measles–mumps–rubella (MMR) coverage was 62%. Immunization coverage for seasonal influenza was 59%. The analysis of timeliness revealed that there was heterogeneity among children with different chronic diseases. A proportional hazard model showed that children with HIV infection had the longest time to complete three doses of DTP, Pol, and HBV, and those with neurological diseases received the first dose of MMR later than the other categories. Causes of missing or delayed vaccination mostly included a concurrent acute disease. Children with chronic diseases should be strictly monitored for routine and recommended vaccinations, and health care providers and families should be properly informed to avoid false contraindications.