Testosterone and estradiol in men with acute ischemic stroke: A North Indian case control

Background: One intriguing aspect of stroke is its higher incidence in men as compared to women. Endogenous sex hormones, testosterone and estradiol, may be responsible for this difference. This research aims to study serum testosterone and estradiol levels in men with acute ischemic stroke (AIS) and to correlate these levels with National Institutes of Health Stroke Scale (NIHSS) score and infarct size in computed tomography (CT). Methods: 100 male patients with AIS and 100 age-matched controls were included in this case-control study. Patients with hemorrhagic stroke, taking hormonal preparations, or suffering from chronic illnesses like tuberculosis (TB), cancer, etc. were excluded. Complete history was obtained including presence of established risk factors and physical examination was done in cases and controls with informed written consent. Severity of stroke in cases was assessed by the NIHSS. CT scan of brain was performed within 72 hours of patient’s admission to hospital. The infarct size was measured in centimeters as the largest visible diameter of the infarct on CT scan. Fasting blood samples were obtained for routine investigations and estimating estradiol and testosterone levels. Results: Mean total testosterone level in cases (223.30 ± 143.44 ng/dl) was significantly lower than that of controls (515.34 ± 172.11 ng/dl) (P < 0.001), while estradiol levels had no significant statistical difference (P = 0.260). A significant inverse correlation was found between total testosterone levels and stroke severity (r = -0.581, P < 0.001) and also, total testosterone levels and infarct size (r = -0.557, P < 0.001). Estradiol levels in patients had no significant correlation with stroke severity (P = 0.618) or infarct size (P = 0.463). Conclusion: Low testosterone levels are associated with increased stroke severity and infarct size in men. Further studies are required to establish whether low testosterone is a cause or effect of ischemic stroke and also to explore the potential benefits of testosterone supplementation in men with AIS.

Quantification of Murine Myocardial Infarct Size using 2D and 4D High Frequency Ultrasound

Background: Ischemic heart disease is the leading cause of death in the United States, Canada, and worldwide. Severe disease is characterized by coronary artery occlusion, loss of blood flow to the myocardium, and necrosis of tissue, with subsequent remodeling of the heart wall, including fibrotic scarring. The current study aims to demonstrate the efficacy of quantitating infarct size via 2D echocardiographic akinetic length and 4D echocardiographic infarct volume and surface area as in vivo analysis techniques. We further describe and evaluate a new surface area strain analysis technique for estimating myocardial infarction (MI) size after ischemic injury. Methods: Experimental MI was induced in mice via left coronary artery ligation. Ejection fraction and infarct size were measured through 2D and 4D echocardiography. Infarct size established via histology was compared to ultrasound-based metrics via linear regression analysis. Results: 2D echocardiographic akinetic length (r = 0.76, p = 0.03), 4D echocardiographic infarct volume (r = 0.85, p = 0.008) and surface area (r = 0.90, p = 0.002) correlate well with histology. While both 2D and 4D echocardiography were reliable measurement techniques to assess infarct, 4D analysis is superior in assessing asymmetry of the left ventricle and the infarct. Strain analysis performed on 4D data also provides additional infarct sizing techniques, which correlate with histology (surface strain: r = 0.94, p < 0.001, transmural thickness: r = 0.76, p = 0.001). Conclusions: 2D echocardiographic akinetic length, 4D echocardiography ultrasound and strain provide effective in vivo methods for measuring fibrotic scarring after MI.

The role of protein kinase C and PI3-kinase in the mechanism of the cardioprotective effect of remote ischemic postconditioning

Background. Acute myocardial infarction (AMI) with ST segment elevation is associated with high incidence of complications. Mortality from AMI is about 5%, which has not decreased in recent years. Revascularization provides recovery of coronary blood flow, but also contributes to the occurrence of reperfusion injury to the heart. Remote ischemic postconditioning (RIPostC) is a promising, non-invasive method that can effectively and safely reduce the infarct size.The aim of the study was to investigate the role of protein kinase C and PI3-kinase in the development of the infarct-limiting effect of remote ischemic postconditioning.Materials and methods. The study was performed on Wistar rats. Coronary artery occlusion (45 min) and reperfusion (2 h) were performed. The infarct size (IS) and the size of area at risk (AAR) were assessed. RIPostC was modeled by applying tourniquets to the hind limbs in the hip joint immediately after the restoration of coronary blood flow. All inhibitors were administered intravenously 10 min before reperfusion.Results. In the control group, the IS / AAR ratio was 44%. RIPostC reduced the IS / AAR ratio by about 50%. Preliminary administration of the protein kinase C inhibitor chelerythrine and the PI3-kinase inhibitor wortmannin eliminated the cardioprotective effect of RIPostC.Conclusion. The mechanism of the infarct-limiting effect of RIPostC is implemented through activation of protein kinase C and PI3-kinase.

Human Lysyl Oxidase Over-Expression Enhances Baseline Cardiac Oxidative Stress but Does Not Aggravate ROS Generation or Infarct Size Following Myocardial Ischemia-Reperfusion

Lysyl oxidase (LOX) is an enzyme critically involved in collagen maturation, whose activity releases H2O2 as a by-product. Previous studies demonstrated that LOX over-expression enhances reactive oxygen species (ROS) production and exacerbates cardiac remodeling induced by pressure overload. However, whether LOX influences acute myocardial infarction and post-infarct left ventricular remodeling and the contribution of LOX to myocardial oxidative stress following ischemia-reperfusion have not been analyzed. Isolated hearts from transgenic mice over-expressing human LOX in the heart (TgLOX) and wild-type (WT) littermates were subjected to global ischemia and reperfusion. Although under basal conditions LOX transgenesis is associated with higher cardiac superoxide levels than WT mice, no differences in ROS production were detected in ischemic hearts and a comparable acute ischemia-reperfusion injury was observed (infarct size: 56.24 ± 9.44 vs. 48.63 ± 2.99% of cardiac weight in WT and TgLOX, respectively). Further, similar changes in cardiac dimensions and function were observed in TgLOX and WT mice 28 days after myocardial infarction induced by transient left anterior descending (LAD) coronary artery occlusion, and no differences in scar area were detected (20.29 ± 3.10 vs. 21.83 ± 2.83% of left ventricle). Our data evidence that, although LOX transgenesis induces baseline myocardial oxidative stress, neither ROS production, infarct size, nor post-infarction cardiac remodeling were exacerbated following myocardial ischemia-reperfusion.

Mettl14 Regulates Cardiac Ishemia/Reperfusion Injury

N6-methyladenosine (m6A) methylation in RNA is a dynamic and reversible modification regulated by methyltransferases and demethylases, which has been reported to participate in many pathological processes of various diseases, including cardiac disorders. This study was designed to investigate an m6A writer Mettl14 on cardiac ischemia–reperfusion (I/R) injury and uncover the underlying mechanism. The m6A and Mettl14 protein levels were increased in I/R hearts and neonatal mouse cardiomyocytes upon oxidative stress. Mettl14 knockout (Mettl14+/−) mice showed pronounced increases in cardiac infarct size and LDH release and aggravation in cardiac dysfunction post-I/R. Conversely, adenovirus-mediated overexpression of Mettl14 markedly reduced infarct size and apoptosis and improved cardiac function during I/R injury. Silencing of Mettl14 alone significantly caused a decrease in cell viability and an increase in LDH release and further exacerbated these effects in the presence of H2O2, while overexpression of Mettl14 ameliorated cardiomyocyte injury in vitro. Mettl14 resulted in enhanced levels of Wnt1 m6A modification and Wnt1 protein but not its transcript level. Furthermore, Mettl14 overexpression blocked I/R-induced downregulation of Wnt1 and β-catenin proteins, whereas Mettl14+/− hearts exhibited the opposite results. Knockdown of Wnt1 abrogated Mettl14-mediated upregulation of β-catenin and protection against injury upon H2O2. Our study demonstrates that Mettl14 attenuates cardiac I/R injury by activating Wnt/β-catenin in an m6A-dependent manner, providing a novel therapeutic target for ischemic heart disease.

Non-Invasive Myocardial Infarction Ischemic Area Estimation Through Four-Dimensional Ultrasound

Background/Objective: Following myocardial infarction, infarct size and cardiac function are significant predictors of long-term prognosis. Most echocardiography studies rely on two-dimensional analysis for estimation of left ventricular function and electrical activity analysis for estimation of infarct area. Other imaging modalities, such as cardiac magnetic resonance imaging, are limited by time, cost, availability, patient tolerance, and incompatible implantable devices. Using an experimental mouse model of myocardial infarction, we hypothesize that four-dimensional ultrasound offers a possible alternative for easy, quick, and reliable estimation of infarct size. Methods: A cohort of 10 mice underwent four-dimensional cardiac imaging at baseline using a small animal high frequency ultrasound. A thoracotomy was subsequently performed, and a suture placed to ligate the left coronary artery approximately midway down the left ventricle. Sequential four-dimensional ultrasound was performed at six time points over 28 days, following which the mice were euthanized. The hearts were then removed and sent for embedding and sectioning into seven uniform segments stained using both H&E and Masson’ s Trichrome. Results: Thus far, we have segmented the imaging and collected end diastolic volume, peak systolic volume, stroke volume, ejection fraction, transmural thickness, and circumferential strain. Additionally, four-dimensional models of the left ventricles have been rendered. Histological embedding, sectioning, and staining is still in progress, and therefore validation against the gold standard is still in process. Conclusion and Impact: Treatment and monitoring of myocardial infarction patients is reliant upon accurate assessment of patient status and prognosis. This study provides initial evidence for the validity of four-dimensional ultrasound as a tool for estimation of myocardial infarction size, providing an alternative to current two-dimensional methods that are less accurate and a more accessible alternative to highly specialized and costly equipment. Improved and accessible imaging methods have the potential to enhance patient care, ultimately improving overall health outcomes.

Relationship Between Exposure to Sulphur Dioxide Air Pollution, White Cell Inflammatory Biomarkers and Enzymatic Infarct Size in Patients With ST-segment Elevation Acute Coronary Syndromes

Aims: To analyse the relationship among air pollutants, markers of inflammation and infarct size in patients with acute coronary syndrome (ACS). Methods: This was a prospective analysis of consecutive patients admitted to hospital because of ACS. Cardiac biomarkers were drawn. The daily mean values of the air pollutants from the day before until 7 days before admission were analysed. The study population was stratified according to infarct size, based on median peak troponin value. Results: Patients were divided into two groups of 108 subjects each, according to median peak troponin value. Patients with extensive MIs had a higher neutrophil:lymphocyte ratio and leukocyte and neutrophil counts than patients with smaller MIs. In addition, they were exposed to higher concentrations of sulphur dioxide (9.7 ± 4.1 versus 8.4 ± 3.1 μg/m3; p=0.009) and lower concentrations of ozone (33.8 ± 13.7 versus 38.6 ± 14.5 μg/m3; p=0.014). Multivariate analysis showed that sulphur dioxide levels (OR 1.12; 95% CI [1.031–1.21]; p=0.007) and neutrophil/lymphocyte ratio (OR 1.08; 95% CI [1.011–1.17]; p=0.024) were independent predictors of infarct size. Conclusion: Patients with extensive MIs had higher white cell inflammatory levels and had been exposed to higher sulphur dioxide concentrations in the ambient air.