RESUMO
Background and aims: Ischemic preconditioning (IPC), i.e., brief periods of ischemia, protect the heart from subsequent prolonged ischemic injury, and reduces infarction size. Myocardial stunning refers to transient loss of contractility in the heart after myocardial ischemia that recovers without permanent damage. The relationship between IPC and myocardial stunning remains incompletely understood. This study aimed primarily to examine the effects of IPC on the relationship between ischemia duration, stunning, and infarct size in an ischemia-reperfusion injury model. Secondarily, this study aimed to examine to which extent the phosphoproteomic changes induced by IPC relate to myocardial contractile function. Methods and results: Rats were subjected to different durations of left anterior descending artery (LAD) occlusion, with or without preceding IPC. Echocardiograms were acquired to assess cardiac contraction in the affected myocardial segment. Infarction size was evaluated using triphenyl tetrazolium chloride staining. Phosphoproteomic analysis was performed in heart tissue from preconditioned and non-preconditioned animals. In contrast to rats without IPC, reversible akinesia was observed in a majority of the rats that were subjected to IPC and subsequently exposed to ischemia of 13.5 or 15â min of ischemia. Phosphoproteomic analysis revealed significant differential regulation of 786 phosphopeptides between IPC and non-IPC groups, with significant associations with the sarcomere, Z-disc, and actin binding. Conclusion: IPC induces changes in phosphosites of proteins involved in myocardial contraction; and both accentuates post-ischemic myocardial stunning and reduces infarct size.
RESUMO
BACKGROUND: Acute hepatitis A is usually a self-limited viral disease but can be severe and even fatal in special groups of patients including those with chronic liver disease and recipients of liver transplantation. To take appropriate preventive measures, it is important to determine the immune status against the hepatitis A virus in patients at risk of grave clinical outcomes following infection. To assess the need for immunization against hepatitis A, we aimed to determine the immune status against hepatitis A in a population of liver transplant recipients. We also investigated the association between hepatitis A immune status and demographic factors such as age and sex, underlying liver disease, source of drinking water, geographical area of residence and socioeconomic status. METHODS: This cross-sectional study was performed on 242 recipients of allogenic liver transplants at Abu Ali Sina Organ Transplant Hospital in Shiraz, Iran, between January 2017 and April 2017. The level of immunity was assessed using hepatitis A antibody detection kits. RESULTS: The rate of immunity against hepatitis A was detected as 88.8% in our study population. In the multivariable logistic regression model, younger age (OR=1.175, P<0.001) and higher education level (OR=2.142, P=0.040) were the main determinants of non-immune status. However, hepatitis A immunity was independent of gender, monthly family income, water supply source, residential area and underlying liver disorder. CONCLUSION: Although a significant proportion of liver transplant recipients in this study showed evidence of natural immunity to hepatitis A, a considerable proportion of younger patients and those with a higher level of education were non-immune. The results of this study signify the importance of screening for hepatitis A immunity in this at-risk population of patients and the need for vaccinating non-immune patients.