Assessment of circumferential endocardial extent of myocardial edema and infarction in patients with reperfused acute myocardial infarction: a cardiovascular magnetic resonance study

Different Changing Patterns of Three NOS-NO System Activities after Ischemia-Reperfusion in Rabbit with AMI

NOS-NO system activity is closely correlated with ischemia-reperfusion injury (IRI) and NOS subtypes were suggested to play different roles in IRI. In this work, the activity of serum NOS, NO levels, and ischemic necrosis after reperfusion in rabbit with AMI at different time was studied. We also explored the NOS-NO system activity changes and its correlation with myocardial ischemia and necrosis. It shows that after reperfusion in rabbits with AMI, NO-NOS system activities present different changes at each time point due to inactivation of NO and iNOS activation, and different experimental animals, ischemia-reperfusion degree, and length of time will also lead to different research results. Therefore, it is necessary to conduct dynamic observation on animals from different species at multi-temporal point under the state of NOS-NO system activities, and simultaneously detect inflammatory factor, MDA, and SOD indexes. Therefore, it is a must to conduct relevant drug research studies to make NOS-NO system activities maintain the level in favor of ideal myocardial ischemia reperfusion.

Cardioprotective Action of Glycyrrhizin on Diabetic Rats with Myocardial Remodeling

Introduction

Cardiovascular disorders are one of the prominent causes of risks of mortality which accounts for high rate of the deaths at a global level. The risk of deadly myocardial infraction grows because of diabetes which even causes the development of heart failure.

Objective

The objective of this study was to understand and study the effect of glycyrrhizin on diabetes suffering rats with myocardial remodeling.

Materials and Methods

Streptozotocin was used for induction of diabetes, and 8–12 weeks later, the assessment of inflammation, fibrosis, and cardiac damage was evaluated. Histopathological analysis and immunohistochemistry was performed to analyze the effect in various groups. Western blotting was performed to understand the proteins expressed in diabetes, and also, their expression was noted in treatment groups.

Results

There was a significant rise in TNF-α, dense fibrosis, and collagen deposits in the STZ diabetes group. The effects of hyperglycemia were significantly improved in the glycyrrhizin-treated group. DAPI, BrDu, and caspase staining was also performed to understand apoptosis in tissues where the diabetic groups reported significant apoptosis, while the effects were significantly lower in the treated group.

Conclusion

All the observations indicate that glycyrrhizin has cardioprotective action in diabetic rats with myocardial remodeling and is due to the inhibition of the NF-κB signaling pathway in the myocardial layer.

Protective effect of glycyrrhizin on myocardial ischemia/reperfusion injury-induced oxidative stress, inducible nitric oxide synthase and inflammatory reactions through high-mobility group box 1 and mitogen-activated protein kinase expression

Glycyrrhizin, which is a type of perennial leguminous caudex, has been used in various Asian countries, including P.R. China, India and Japan, for thousands of years. The present study was designed to investigate the protective effect of glycyrrhizin on myocardial ischemia/reperfusion (I/R) injury through oxidative stress, inducible nitric oxide synthase (iNOS), and inflammatory reactions via high-mobility group box 1 (HMGB1) and mitogen-activated protein kinase (MAPK) expression. Sprague-Dawley rats were divided into five groups: Sham; myocardial I/R injury + non-treated; myocardial I/R injury + 2 mg/kg glycyrrhizin; myocardial I/R injury + 4 mg/kg glycyrrhizin; and myocardial I/R injury + 10 mg/kg glycyrrhizin. Pre-treatment with glycyrrhizin significantly reduced infarct size and inhibited creatine kinase, creatine kinase-MB, lactate dehydrogenase and cardiac troponin T activities in rats with myocardial I/R injury. Furthermore, glycyrrhizin treatment significantly suppressed oxidative stress, iNOS protein expression and inflammatory reactions in rats with myocardial I/R injury. Additionally, treatment with glycyrrhizin significantly decreased the release of HMGB1 from the cerebral cortex into the serum in rats with myocardial I/R injury. Notably, glycyrrhizin significantly suppressed p-ERK, p-p38 MAPK and p-c-Jun N-terminal kinase protein expressions, and promoted extracellular signal-regulated kinase protein expression in rats with myocardial I/R injury. Collectively, the present study indicates that the protective effect of glycyrrhizin may reduce myocardial I/R injury through oxidative stress, iNOS and inflammatory reactions, via HMGB1 and MAPK expression.

Metformin ameliorates gender-and age-dependent hemodynamic instability and myocardial injury in murine hemorrhagic shock

Severity of multiple organ failure is significantly impacted by age and gender in patients with hemorrhagic shock. However, the molecular mechanisms underlying the enhanced organ injury are not fully understood. AMP-activated protein kinase (AMPK) is a pivotal orchestrator of metabolic responses during stress. We investigated whether hemorrhage-induced myocardial injury is age and gender dependent and whether treatment with metformin, an AMPK activator, affords cardioprotective effects. C57/BL6 young (3-5months) and mature (9-12months) male and female mice were subjected to hemorrhagic shock by blood withdrawing followed by resuscitation with blood and Lactated Ringer's solution. Vehicle-treated young and mature mice of both genders had a similar elevation of plasma inflammatory cytokines at 3h after resuscitation. However, vehicle-treated male mature mice experienced hemodynamic instability and higher myocardial damage than young male mice, as evaluated by echocardiography, histology and cardiovascular injury biomarkers. There was also a gender-dependent difference in cardiovascular injury in the mature group as vehicle-treated male mice exhibited more severe organ injury than female mice. At molecular analysis, vehicle-treated mature mice of both genders exhibited a marked downregulation of AMPKα activation and nuclear translocation of peroxisome proliferator-activated receptor γ co-activator α when compared with young mice. Treatment with metformin improved cardiovascular function and survival in mature animals of both genders. However, specific cardioprotective effects of metformin were gender-dependent. Metformin did not affect hemodynamic or inflammatory responses in young animals. Thus, our data suggest that targeting metabolic recovery with metformin may be a potential treatment approach in severe hemorrhage in adult population.

Sector-Based Assessment of Infarct Size on Late-Gadolinium-Enhancement MRI in a Mouse Model of Acute Myocardial Infarction

Scoring of myocardial infarction (MI) disease extent in cardiac magnetic resonance (CMR) images has been generally presented in terms of area-based infarct size. However, gradual thinning of the infarcted wall and compensatory hypertrophy of the noninfarcted remote wall during left ventricular (LV) remodeling after MI complicate the accuracy of infarct size measurement. In this study, we measured and compared infarct sizes in mice on late gadolinium enhancement (LGE) images using area-, length-, and radial sector-based methods.MI was induced by permanent ligation of the left coronary artery (n = 6). LGE images were acquired 30 minutes after intravenous injection of Gd-DTPA-BMA. Percentages of infarct size (%Area, %Length, and %Sector) on the LGE images were calculated and compared with histological findings.Infarct sizes obtained by an area-based approach were smaller than those obtained by other measurements. The area-based approach underestimated infarct size compared with the length-based approach. Most infarct sizes measured by each method demonstrated a similar trend, with maximum values determined by sector-based measurements using a mean + SD threshold. Spearman's rank correlation coefficients indicated that the 3 measurements were strongly correlated (P < 0.05) to each other. Significant differences and trends were observed between sector-based infarct sizes with different thresholds when 16 or more sectors were used.In conclusion, our study demonstrated that methods used for the histological calculation of infarct size could be applied to CMR analysis. Moreover, our results showed a similar trend to histological assessment. Sector-based CMR approaches can be useful for infarct size measurement.

Contribution of Electrocardiogram in the Differentiation of Cardiac Amyloidosis and Nonobstructive Hypertrophic Cardiomyopathy

Due to similar manifestations of hypertensive ventricular walls and abnormal ventricular compliance, it is difficult to differentiate cardiac amyloidosis (CA) and nonobstructive hypertrophic cardiomyopathy (NOHCM) clinically. The purpose of the study was to investigate the value of electrocardiography (ECG) in the differentiation of the two diseases.

METHODS

We enrolled 46 consecutive patients with CA and 64 patients with NOHCM and compared their ECG characteristics.Compared with NOHCM patients, the ECG of CA patients showed more low voltage on limb leads (50% versus 1.6%), atrioventricular block (21.7% versus 4.7%), pseudo-infarct pattern (84.8% versus 39.1%), and longer QRS duration (104 ± 25 versus 98 ± 14 ms) (all P < 0.05). The QRS complex voltage of avR demonstrated the highest diagnostic performance (sensitivity 89%, specificity 94%, cut-off value 0.45mV) as assessed by ROC analysis. The combination of the R wave voltage of I and avR reached a sensitivity of 95% and a specificity of 87% for the diagnosis of amyloidosis.Compared with NOHCM patients, CA patients showed more ECG characteristics of low voltage on limb leads, pseudo-infarct pattern, atrioventricular block, and longer QRS duration. The combination of the R wave voltage of I, avR, and QRS was of diagnostic value in the differentiation of CA from NOHCM.

Impact of low signal intensity assessed by cine magnetic resonance imaging on detection of poorly viable myocardium in patients with prior myocardial infarction

Late gadolinium enhancement magnetic resonance imaging (LGE-MRI) has been established as a modality to detect myocardial infarction (MI). However, the use of gadolinium contrast is limited in patients with advanced renal dysfunction. Although the signal intensity (SI) of infarct area assessed by cine MRI is low in some patients with prior MI, the prevalence and clinical significance of low SI has not been evaluated. The aim of this study was to evaluate how low SI assessed by cine MRI may relate to the myocardial viability in patients with prior MI. Fifty patients with prior MI underwent both cine MRI and LGE-MRI. The left ventricle was divided into 17 segments. The presence of low SI and the wall motion score (WMS) of each segment were assessed by cine MRI. The transmural extent of infarction was evaluated by LGE-MRI. LGE was detected in 329 of all 850 segments (39%). The low SI assessed by cine MRI was detected in 105 of 329 segments with LGE (32%). All segments with low SI had LGE. Of all 329 segments with LGE, the segments with low SI showed greater transmural extent of infarction (78 [72 - 84] % versus 53 [38 - 72] %, P < 0.01), thinner wall (4.0[3.1 - 4.8] mm versus 6.5 [5.2 - 8.1] mm, P < 0.01), and higher WMS (4.0 [4.0 - 4.0] versus 2.0 [2.0 - 3.0], P < 0.01). The low SI assessed by cine MRI may be effective for detecting poorly viable myocardium in patients with prior MI.