Myocardial tissue troponins T and I. An immunohistochemical study in experimental models of myocardial ischemia

Postmortem Immunohistochemical Findings in Early Acute Myocardial Infarction: A Systematic Review

The diagnosis of early acute myocardial infarction is of particular importance in forensic practice considering the frequency of sudden cardiac death and the difficulty of positively identifying it through classical histological methods if survival is less than 6 h. This article aims to analyze potential immunohistochemical markers that could be useful in diagnosing acute myocardial infarction within the first 6 h of its onset. We conducted an extensive evaluation of the literature according to the PRISMA guidelines for reporting systematic literature reviews. We searched the Web of Science and PubMed databases from their inception to 2023 using the following keywords: "myocardial infarction" and "immunohistochemistry". Fifteen studies met the inclusion criteria. Immunohistochemical markers as complement factors and CD59, myoglobin, fibrinogen, desmin, tumor necrosis factor alpha (TNF-α), P-38, JNK (Jun N Terminal Kinase), transforming growth factor β1 (TGF-β1), cardiac troponins, fibronectin, H-FABP (heart fatty acid binding protein), dityrosine, fibronectin, CD15, IL-1β, IL-6, IL-15, IL-8, MCP-1, ICAM-1, CD18, and tryptase can be used to identify the first six hours of acute myocardial infarction. These markers are mostly studied in experimental animal models. It is necessary to conduct extensive studies on human myocardial tissue fragments, which will involve the analysis of several immunohistochemical markers and careful analysis of the available data on perimortem events, resuscitation, and postmortem intervals in the context of a uniform laboratory methodology.

miR-338-5p regulated the NF-κB/MAPK pathway to alleviate inflammation and oxidative stress by targeting IL-6 in rats with atrial fibrillation

The aim of this study was to investigate the functional effect of miR-338-5p targeting IL-6 on NF-κB/MAPK pathway-mediated inflammation and oxidative stress in atrial fibrillation (AF) rats. AF model rats were generated by tail vein injection of 0.1 mL Ach-CaCl2 mixture. The overexpression and suppression of miR-338-5p were established by injecting a miR-338-5p-agomir and a miR-338-5p-antagomir, respectively, into AF rats. Cardiac morphological changes were detected by H&E and Masson staining. The levels of ROS, SOD, T-AOC, IL-6, IL-1β, and TNF-α were detected via ELISA. Dual luciferase assays, qRT‒PCR, and western blotting were used to verify that miR-338-5p targets IL-6. The expression of NF-κB/MAPK pathway proteins was detected by western blot. Overexpression of miR-338-5p ameliorated heart damage in AF rats. Increased miR-338-5p reduced the levels of CK, CK-MB, and cTnT to alleviate myocardial injury. Furthermore, overexpression of miR-338-5p relieved inflammation and oxidative stress by downregulating SOD and T-AOC and upregulating IL-6, IL-1β, TNF-α, and ROS. Further research revealed that upregulation of miR-338-5p reduced the protein levels of p-p38, p-p65 and p-ERK1/2. The opposite results were obtained following miR-338-5p-antagomir treatment. Taken together, these findings indicate that the upregulation of miR-338-5p alleviated inflammation and oxidative stress by targeting IL-6 to inhibit the NF-κB/MAPK pathway, thus providing a new therapeutic target for AF.

Cardiac Troponin Serum Concentration Measurement Is Useful Not Only in the Diagnosis of Acute Cardiovascular Events

Cardiac troponin serum concentration is the primary marker used for the diagnosis of acute coronary syndrome. Moreover, the measurement of cardiac troponin concentration is important for risk stratification in patients with pulmonary embolism. The cardiac troponin level is also a general marker of myocardial damage, regardless of etiology. The purpose of this study is to conduct a literature review and present the most important information regarding the current state of knowledge on the cardiac troponin serum concentration in patients with chronic cardiovascular disease (CVD), as well as on the relationships between cardiac troponin serum concentration and features of subclinical cardiovascular dysfunction. According to research conducted to date, patients with CVDs, such as chronic coronary syndrome, chronic lower extremities' ischemia, and cerebrovascular disease, are characterized by higher cardiac troponin concentrations than people without a CVD. Moreover, the literature data indicate that the concentration of cardiac troponin is correlated with markers of subclinical dysfunction of the cardiovascular system, such as the intima-media thickness, pulse wave velocity, ankle-brachial index, coronary artery calcium index (the Agatston score), and flow-mediated dilation. However, further research is needed in various patient subpopulations and in different clinical contexts.

Forensic significance of intracardiac expressions of Nrf2 in acute myocardial ischemia

When exposed to oxidative and electrophilic stress, a protective antioxidant response is initiated by nuclear factor erythroid 2-related factor 2 (Nrf2). However, the extent of its importance in the forensic diagnosis of acute ischemic heart diseases (AIHD), such as myocardial infarction (MI), remains uncertain. On the other hand, immunohistochemical analyses of fibronectin (FN) and the terminal complement complex (C5b-9) prove valuable in identifying myocardial ischemia that precedes necrosis during the postmortem diagnosis of sudden cardiac death (SCD). In this study, we investigated the immunohistochemical levels of Nrf2, FN, and C5b-9 in human cardiac samples to explore their forensic relevance for the identification of acute cardiac ischemia. Heart samples were obtained from 25 AIHD cases and 39 non-AIHD cases as controls. Nrf2 was localized in the nuclei of cardiomyocytes, while FN and C5b-9 were detected in the myocardial cytoplasm. The number of intranuclear Nrf2 positive signals in cardiomyocytes increased in AIHD cases compared to control cases. Additionally, the grading of positive portions of cardiac FN and C5b-9 in the myocardium was also significantly enhanced in AIHD, compared to controls. Collectively, these results indicate that the immunohistochemical investigation of Nrf2 combined with FN, and/or C5b-9 holds the potential for identifying early-stage myocardial ischemic lesions in cases of SCD.

Diagnostic value and utility of commonly used biomarkers of cardiac and renal function in cardiorenal syndromes: a narrative review

Cardiorenal syndrome (CRS), first defined in 2004 as a consequence of the interactions between the kidneys and other circulatory departments leading to acute heart failure, has since been recognized as a complex clinical entity that is hard to define, diagnose and classify. The framework for the classification of CRS according to pathophysiologic background was laid out in 2008, dividing CRS into five distinct phenotypes. However, determining the timing of individual organ injuries and making a diagnosis of either renal or cardiac failure remains an elusive task. In clinical practice, the diagnosis and phenotyping of CRS is mostly based on using laboratory biomarkers in order to directly or indirectly estimate the degree of end-organ functional decline. Therefore, a well-educated clinician should be aware of the effects that the reduction of renal and cardiac function has on the diagnostic and predictive value and properties of the most commonly used biomarkers (e.g. troponins, N-terminal pro-brain natriuretic peptide, serum creatinine etc). They should also be acquainted, on a basic level, with emerging biomarkers that are specific to either the degree of glomerular integrity (cystatin C) or tubular injury (neutrophil gelatinase-associated lipocalin). This narrative review aims to provide a scoping overview of the different roles that biomarkers play in both the diagnosis of CRS and the prognosis of the disease in patients who have been diagnosed with it, along with highlighting the most important pitfalls in their interpretation in the context of impaired renal and/or cardiac function.

Pathological Aspects and Immunohistochemical Evaluation of Troponin C in the Cardiovascular System of Dogs with Pheochromocytoma

Functional pheochromocytomas secrete catecholamines and have been associated with cardiovascular lesions in dogs. This study aimed to describe the post-mortem pathological findings in the cardiovascular system of dogs with pheochromocytoma and to evaluate the expression of cardiac troponin C in these dogs using immunohistochemical analysis. Twelve cases were identified, with a mean age of 10.6 years. The heart of all dogs was enlarged and with concentric hypertrophy of the left ventricular myocardium. Histological analysis showed cardiomyocyte necrosis and degeneration in the myocardium, with frequent bands of contraction, fibrosis, inflammation, and thickening of the medium-calibre arteries in the myocardium. There was a marked decrease or absence of immunolabeling in necrotic cardiomyocytes. We conclude that IHC for troponin C can be a useful tool for detecting myocardial necrosis in dogs with pheochromocytomas, including early cases of necrosis with only incipient cardiac changes where overt histologic abnormalities are not immediately apparent in the cardiomyocytes.

Cardiac troponin release following coronary artery bypass grafting: mechanisms and clinical implications

The use of biomarkers is undisputed in the diagnosis of primary myocardial infarction (MI), but their value for identifying MI is less well studied in the postoperative phase following coronary artery bypass grafting (CABG). To identify patients with periprocedural MI (PMI), several conflicting definitions of PMI have been proposed, relying either on cardiac troponin (cTn) or the MB isoenzyme of creatine kinase, with or without supporting evidence of ischaemia. However, CABG inherently induces the release of cardiac biomarkers, as reflected by significant cTn concentrations in patients with uncomplicated postoperative courses. Still, the underlying (patho)physiological release mechanisms of cTn are incompletely understood, complicating adequate interpretation of postoperative increases in cTn concentrations. Therefore, the aim of the current review is to present these potential underlying mechanisms of cTn release in general, and following CABG in particular (Graphical Abstract). Based on these mechanisms, dissimilarities in the release of cTnI and cTnT are discussed, with potentially important implications for clinical practice. Consequently, currently proposed cTn biomarker cut-offs by the prevailing definitions of PMI might warrant re-assessment, with differentiation in cut-offs for the separate available assays and surgical strategies. To resolve these issues, future prospective studies are warranted to determine the prognostic influence of biomarker release in general and PMI in particular.

Correlation Between Cardiac Index, Plasma Troponin I, Myocardial Histopathology, CPB and AoX Duration in Glutamine versus No Glutamine Administered Patients with Low Ejection Fraction Undergoing Elective On-Pump CABG Surgery: Secondary Analysis of an RCT

Purpose

On-pump coronary artery bypass graft (CABG) causes myocardial ischemia, through the cardiopulmonary bypass (CPB) and aortic cross-clamping (AoX). Glutamine supplementation protects cardiac cells during cardiac ischemia. This study analysed the correlation between cardiac index (CI), plasma troponin I, myocardial histopathology, CPB and AoX duration in low ejection fraction patients receiving glutamine and no glutamine undergoing elective on-pump CABG.

Material and Methods

This was a secondary analysis of a double-blind, randomised controlled trial of 60 patients, split into control and intervention (glutamine) groups. Glutamine was administered at a dose of 0.5 g/kg/24 hours. There were 29 patients in each respective groups after a total of two patients dropped out.

Results

A negative correlation (p = 0.037) was observed between CPB duration and CI at 6 hours after CPB in the glutamine group. A positive correlation (p = 0.002) was also observed between AoX duration and plasma troponin I at 6 hours after CPB in the control group. However, no correlation was observed between myocardial histopathology and plasma troponin I level at 5 minutes after CPB.

Conclusion

Significant negative correlation between CPB duration and CI at 6 hours after CPB in the glutamine group, along with significant positive correlation between AoX duration and plasma troponin I level at 6 hours after CPB in the control group demonstrated the myocardial protection qualities of intravenous glutamine administration in patients with low ejection fraction undergoing elective on-pump CABG surgeries.

Cellular recovery after prolonged warm ischaemia of the whole body

After cessation of blood flow or similar ischaemic exposures, deleterious molecular cascades commence in mammalian cells, eventually leading to their death^1,2. Yet with targeted interventions, these processes can be mitigated or reversed, even minutes or hours post mortem, as also reported in the isolated porcine brain using BrainEx technology³. To date, translating single-organ interventions to intact, whole-body applications remains hampered by circulatory and multisystem physiological challenges. Here we describe OrganEx, an adaptation of the BrainEx extracorporeal pulsatile-perfusion system and cytoprotective perfusate for porcine whole-body settings. After 1 h of warm ischaemia, OrganEx application preserved tissue integrity, decreased cell death and restored selected molecular and cellular processes across multiple vital organs. Commensurately, single-nucleus transcriptomic analysis revealed organ- and cell-type-specific gene expression patterns that are reflective of specific molecular and cellular repair processes. Our analysis comprises a comprehensive resource of cell-type-specific changes during defined ischaemic intervals and perfusion interventions spanning multiple organs, and it reveals an underappreciated potential for cellular recovery after prolonged whole-body warm ischaemia in a large mammal.

Analysis of Time Series Gene Expression and DNA Methylation Reveals the Molecular Features of Myocardial Infarction Progression

Myocardial infarction (MI) is one of the deadliest diseases in the world, and the changes at the molecular level after MI and the DNA methylation features are not clear. Understanding the molecular characteristics of the early stages of MI is of significance for the treatment of the disease. In this study, RNA-seq and MeDIP-seq were performed on heart tissue from mouse models at multiple time points (0 h, 10 min, 1, 6, 24, and 72 h) to explore genetic and epigenetic features that influence MI progression. Analysis based on a single point in time, the number of differentially expressed genes (DEGs) and differentially methylated regions (DMRs) increased with the time of myocardial infarction, using 0 h as a control group. Moreover, within 10 min of MI onset, the cells are mainly in immune response, and as the duration of MI increases, apoptosis begins to occur. Analysis based on time series data, the expression of 1012 genes was specifically downregulated, and these genes were associated with energy metabolism. The expression of 5806 genes was specifically upregulated, and these genes were associated with immune regulation, inflammation and apoptosis. Fourteen transcription factors were identified in the genes involved in apoptosis and inflammation, which may be potential drug targets. Analysis based on MeDIP-seq combined with RNA-seq methodology, focused on methylation at the promoter region. GO revealed that the downregulated genes with hypermethylation at 72 h were enriched in biological processes such as cardiac muscle contraction. In addition, the upregulated genes with hypomethylation at 72 h were enriched in biological processes, such as cell-cell adhesion, regulation of the apoptotic signaling pathway and regulation of angiogenesis. Among these genes, the Tnni3 gene was also present in the downregulated model. Hypermethylation of Tnni3 at 72 h after MI may be an important cause of exacerbation of MI.

High-sensitivity Troponin I and Ablation Effectiveness Quotient after Ablation Index-guided pulmonary vein isolation-markers of arrhythmia recurrence?

BACKGROUND

There are conflicting data regarding the relationship between high-sensitivity cardiac Troponin I (Hs-cTnI) and the ablation effectiveness quotient (AEQ) with arrhythmia recurrence following atrial fibrillation (AF) ablation. Our goals were to evaluate the impact of the Ablation Index (AI) software on Hs-cTnI and AEQ levels and to assess whether these markers are predictors of arrhythmia recurrence.

METHODS

Prospective single-center study of 75 consecutive patients referred for paroxysmal AF ablation from October 2017 to January 2019. Procedural endpoints and 2-year outcomes were assessed and compared to those of 75 propensity score-matched patients submitted to non-AI-guided pulmonary vein isolation (PVI) [control group].

RESULTS

Compared to the control group, patients having AI-guided PVI had lower Hs-cTnI values (1580 [IQR 1180-2140] ng/L vs. 2600 [IQR 1840 - 3900], p < 0.001) and a lower AEQ (0.9 [IQR 0.6-1.2] ng/L/s vs. 1.4 [0.8-1.6] ng/L/s, p < 0.001). After a median follow-up of 26 (IQR 20-32) months, there was a significant reduction in arrhythmia recurrence in the AI group (15% vs. 31%, HR 0.67 [95% CI, 0.32-1.40], p = 0.02). However, neither Hs-cTnI nor AEQ was predictors of arrhythmia recurrence in AI-guided PVI.

CONCLUSIONS

The use of the AI software led to reduced levels of Hs-cTnI and lower AEQ in AF patients submitted to PVI. However, none of these markers predicted arrhythmia recurrence.

Myocardial Protecting Role of Glutamine in Patients with Low Ejection Fraction Undergoing Elective On-Pump Coronary Artery Bypass Graft Surgery

Purpose

Myocardial injury due to on-pump coronary artery bypass grafting (CABG) in patients with low ejection fraction (EF) is associated with poor outcomes. This study determines whether intravenous glutamine could protect the myocardium during on-pump CABG in patients with low EF.

Materials and Methods

This was a double-blind, randomized controlled trial to assess glutamine as a myocardial protector during on-pump CABG in patients with left ventricle EF of 31–50%, conducted from January to October 2021. Patients in the glutamine group (n = 30) received 0.5 g/kg of 20% glutamine solution diluted with 0.9% NaCl up to 500 mL in total volume over a period of 24 hours. Patients in the control group (n = 30) received 0.9% NaCl over the same period. The primary outcomes were plasma troponin I and plasma glutamine levels. Secondary outcomes included α-ketoglutarate (α-KG) levels and histopathology scoring of the right atrial appendage tissue, plasma lactate levels, hemodynamic measurement, and morbidity.

Results

Twenty-nine patients from each group (58 in total) were included in the analysis. Plasma troponin I levels at 6 and 24 hours after cardiopulmonary bypass (CPB) were significantly lower in the glutamine than the control group (mean 3.43 ± 1.51 ng/mL vs mean 4.41 ± 1.89 ng/mL; p = 0.034; median 3.08 ng/mL [min–max: 1.30–6.59] vs median 3.77 ng/mL [min–max: 0.00–36.53]; p = 0.038, respectively). Plasma glutamine levels at 24 hours after CPB were significantly higher in the glutamine than the control group (mean 935.42 ± 319.10 μmol/L vs mean 634.79 ± 243.89 μmol/L, p = 0.001). Plasma lactate levels at 6 and 24 hours after CPB were significantly lower in the glutamine than the control group (median 5.30 mmol/L [min-max: 1.20–9.50] vs median 5.70 mmol/L [min-max: 2.80–11.30], p = 0.042; mean 2.08 ± 0.67 mmol/L vs mean 2.46 ± 0.69 mmol/L, p = 0.044, respectively). Myocardial injury score was significantly lower in the glutamine than the control group (mean 1.30 ± 0.24 vs mean 1.48 ± 0.26, p = 0.011).

Conclusion

Perioperative administration of 0.5 g/kg intravenous glutamine solution over the period of 24 hours has myocardial protection effect in patients with low EF who undergo elective on-pump CABG.

Effect of preoperative administration of atenolol to dogs with pulmonic stenosis undergoing interventional procedures

Background

Beta‐blockade is sometimes used in dogs with pulmonic stenosis with the intent of reducing frequency of ventricular arrhythmias during right heart catheterization.

Objectives

To evaluate if pretreatment with atenolol reduces frequency of ventricular arrhythmias, anesthetist interventions, or shortens procedure time.

Animals

Thirty dogs with pulmonic stenosis scheduled for interventional procedures.

Methods

Single center, prospective, randomized, open‐label study. Dogs were randomized to treatment with atenolol or no treatment preoperatively for a minimum of 10 days. Variables recorded included heart rate, arrhythmias and complexity, total procedure time and administration of antiarrhythmic treatment, vasopressors, positive chronotropes, or fluid boluses.

Results

Fifteen dogs were enrolled in each group. Dogs receiving atenolol had lower mean heart rates during the procedure (atenolol 100 ± 11 bpm vs untreated 115 ± 19 bpm, P = .01). There were no significant differences between the atenolol and untreated groups in the frequency of ventricular ectopic complexes (535 [6‐5296] vs 553 [79‐2863], P = .9), ventricular couplets (46 [0‐481] vs 29 [3‐121], P = .59), ventricular triplets (20 [0‐265] vs 16 [1‐82], P = .67), ventricular tachycardia (8 [0‐224] vs 8 [1‐118], P = .99), proportion exhibiting R‐on‐T phenomenon (11/15 vs 14/15, P = .33), proportion receiving intraoperative lidocaine (1/15 vs 3/15, P = .6), vasopressors/positive chronotropes (11/15 vs 5/15, P = .06), or fluid boluses (12/15 vs 7/15, P = .13). The procedure time was similar (atenolol 41 [23‐68] min vs untreated 35 [18‐98] min, P = .91).

Conclusions and Clinical Importance

No benefit of preoperative atenolol treatment was identified in this small group of dogs.

The [2Fe-2S] protein CISD2 plays a key role in preventing iron accumulation in cardiomyocytes

Considered a key aging gene, CISD2, encoding CDGSH iron-sulfur domain-containing protein 2, plays a central role in regulating calcium homeostasis, preventing mitochondrial dysfunction, and the activation of autophagy and apoptosis in different cells. Here, we show that cardiomyocytes from CISD2-null mice accumulate high levels of iron and contain high levels of transferrin receptor and ferritin. Using proteomics and transmission electron microscopy, we further show that the lack of CISD2 induces several features of the aging process in young mice, but other features are not induced. Taken together, our findings suggest that CISD2 protects cardiomyocytes from overaccumulation of iron, which is common in aging hearts and can contribute to the pathogenesis of heart failure.

Influencing Factors on Postmortem Protein Degradation for PMI Estimation: A Systematic Review

The present review provides an overview of the current research status on the effects of influencing factors on postmortem protein degradation used to estimate the PMI (postmortem interval). Focus was set on characteristics of internal and external influencing factors and the respective susceptibility and/or robustness of protein degradation. A systematic literature search up to December 2020 was conducted on the effect of influencing factors investigated in the context of postmortem protein degradation in the tissues of animals and humans using the scientific databases PubMed and Google Scholar, as well as the reference lists of eligible articles. We identified ten studies investigating a total of seven different influencing factors in degrading tissues/organs (n = 7) of humans and animals using six different methodological approaches. Although comparison of study outcomes was impeded by the high variety of investigated factors, and by high risk of bias appraisals, it was evident that the majority of the influencing factors concerned affected protein degradation, thus being able to modulate the precision of protein degradation-based PMI estimation. The results clearly highlight the need for a thorough screening for corresponding factors to enable the introduction of appropriate correction factors and exclusion criteria. This seems especially relevant for the protein degradation-based study of human PMI to increase the reliability and precision of the method and to facilitate a broader applicability in routine forensic casework.

Garlic Derived Diallyl Trisulfide in Experimental Metabolic Syndrome: Metabolic Effects and Cardioprotective Role

This study aimed to examine the effects of diallyl trisulfide (DATS), the most potent polysulfide derived from garlic, on metabolic syndrome and myocardial function in rats with metabolic syndrome (MetS). For that purpose, we used 36 male Wistar albino rats divided into control rats, rats with MetS and MetS rats treated with 40 mg/kg of DATS every second day for 3 weeks. In the first part, we studied the impact of DATS on MetS control and found that DATS significantly raised H₂S, decreased homocysteine and glucose levels and enhanced lipid and antioxidative, while reducing prooxidative parameters. Additionally, this polysulfide improved cardiac function. In the second part, we investigated the impact of DATS on ex vivo induced ischemia/reperfusion (I/R) heart injury and found that DATS consumption significantly improved cardiodynamic parameters and prevented oxidative and histo-architectural variation in the heart. In addition, DATS significantly increased relative gene expression of eNOS, SOD-1 and -2, Bcl-2 and decreased relative gene expression of NF-κB, IL-17A, Bax, and caspases-3 and -9. Taken together, the data show that DATS can effectively mitigate MetS and have protective effects against ex vivo induced myocardial I/R injury in MetS rat.

Postmortem Protein Degradation as a Tool to Estimate the PMI: A Systematic Review

Objectives: We provide a systematic review of the literature to evaluate the current research status of protein degradation-based postmortem interval (PMI) estimation. Special attention is paid to the applicability of the proposed approaches/methods in forensic routine practice. Method: A systematic review of the literature on protein degradation in tissues and organs of animals and humans was conducted. Therefore, we searched the scientific databases Pubmed and Ovid for publications until December 2019. Additional searches were performed in Google Scholar and the reference lists of eligible articles. Results: A total of 36 studies were included. This enabled us to consider the degradation pattern of over 130 proteins from 11 different tissues, studied with different methods including well-established and modern approaches. Although comparison between studies is complicated by the heterogeneity of study designs, tissue types, methods, proteins and outcome measurement, there is clear evidence for a high explanatory power of protein degradation analysis in forensic PMI analysis. Conclusions: Although only few approaches have yet exceeded a basic research level, the current research status provides strong evidence in favor of the applicability of a protein degradation-based PMI estimation method in routine forensic practice. Further targeted research effort towards specific aims (also addressing influencing factors and exclusion criteria), especially in human tissue will be required to obtain a robust, reliable laboratory protocol, and collect sufficient data to develop accurate multifactorial mathematical decomposition models.

Immunohistochemistry in the Detection of Early Myocardial Infarction: Systematic Review and Analysis of Limitations Because of Autolysis and Putrefaction

The postmortem diagnosis of acute myocardial infarction is one of the main problems in forensic practice, especially in cases in which death occurs soon after (from minutes to a few hours) the onset of the ischemic damage. Several authors have highlighted the possibility to overcome the limits of conventional histology in this diagnosis by utilizing immunohistochemistry. In the present research, we examined over 30 scientific studies and picked out over 20 main immunohistochemical antigens analyzed with a view to enabling the rapid diagnosis of early myocardial infarction. The aim of our review was to examine and summarize all the principal markers studied to date and also to consider their limitations, including protein alteration because of cadaveric autolysis and putrefaction.

Secretome Analysis of Cardiomyocytes Identifies PCSK6 (Proprotein Convertase Subtilisin/Kexin Type 6) as a Novel Player in Cardiac Remodeling After Myocardial Infarction

BACKGROUND

Acute occlusion of a coronary artery results in swift tissue necrosis. Bordering areas of the infarcted myocardium can also experience impaired blood supply and reduced oxygen delivery, leading to altered metabolic and mechanical processes. Although transcriptional changes in hypoxic cardiomyocytes are well studied, little is known about the proteins that are actively secreted from these cells.

METHODS

We established a novel secretome analysis of cardiomyocytes by combining stable isotope labeling and click chemistry with subsequent mass spectrometry analysis. Further functional validation experiments included ELISA measurement of human samples, murine left anterior descending coronary artery ligation, and adeno-associated virus 9-mediated in vivo overexpression in mice.

RESULTS

The presented approach is feasible for analysis of the secretome of primary cardiomyocytes without serum starvation. A total of 1026 proteins were identified to be secreted within 24 hours, indicating a 5-fold increase in detection compared with former approaches. Among them, a variety of proteins have not yet been explored in the context of cardiovascular pathologies. One of the secreted factors most strongly upregulated upon hypoxia was PCSK6 (proprotein convertase subtilisin/kexin type 6). Validation experiments revealed an increase of PCSK6 on mRNA and protein level in hypoxic cardiomyocytes. PCSK6 expression was elevated in hearts of mice after 3 days of ligation of the left anterior descending artery, a finding confirmed by immunohistochemistry. ELISA measurements in human serum also indicate distinct kinetics for PCSK6 in patients with acute myocardial infarction, with a peak on postinfarction day 3. Transfer of PCSK6-depleted cardiomyocyte secretome resulted in decreased expression of collagen I and III in fibroblasts compared with control treated cells, and small interfering RNA-mediated knockdown of PCSK6 in cardiomyocytes impacted transforming growth factor-β activation and SMAD3 (mothers against decapentaplegic homolog 3) translocation in fibroblasts. An adeno-associated virus 9-mediated, cardiomyocyte-specific overexpression of PCSK6 in mice resulted in increased collagen expression and cardiac fibrosis, as well as decreased left ventricular function, after myocardial infarction.

CONCLUSIONS

A novel mass spectrometry-based approach allows investigation of the secretome of primary cardiomyocytes. Analysis of hypoxia-induced secretion led to the identification of PCSK6 as being crucially involved in cardiac remodeling after acute myocardial infarction.

Increased Plasma Cardiac Troponin I in Live-Stranded Cetaceans: Correlation with Pathological Findings of Acute Cardiac Injury

Capture myopathy (CM), is a syndrome that occurs as the result of the stress during and after capture, handling, restraint, and transport of wild animals. Although CM has been described for many species of cetaceans, characterization of the acute cardiac injury - an important component of this syndrome - are still scarce. In this study, we firstly estimated a normal range for cardiac troponin I (cTnI) on cetaceans. Here, through biochemical analysis (especially of cTnI) and histopathological, histochemical, and immunohistochemical correlations with decreased troponin immunolabelling, we studied the cardiac injury in live-stranded cetaceans. Nine cetaceans which stranded alive on the Canary Islands (January 2016 - June 2019) were included in this study. Sampled individuals presented elevated values of plasma cTnI, which were correlated to histopathological lesions comprised of vascular changes and acute degenerative lesions. Immunohistochemically, injured cardiomyocytes showed a decreased intrafibrillar troponin immunoreaction. This is the first attempt to establish a normal baseline range for cTnI in cetaceans, and the first study comparing plasma biomarkers values with histopathological and immunohistochemical findings. This approach allowed us to demonstrate the degree of cardiac damage as a result of injury, consistent with ischemia-reperfusion lesions. The knowledge gained here could improve decision-making procedures during stressful situations, mainly in live-strandings, handling, and rehabilitation, thereby reducing the mortality of cetaceans.

Capture Myopathy and Stress Cardiomyopathy in a Live-Stranded Risso's Dolphin (Grampus griseus) in Rehabilitation

Simple Summary

Free-living cetaceans are threatened, daily, by a wide variety of stressful situations. An example is provided by live-stranding, in which a cetacean is alive on the beach or in shallow water, and unable to free itself and resume its normal activity. This is the first case of capture myopathy and stress cardiomyopathy in a live-stranded juvenile male Risso’s dolphin (Grampus griseus) with subsequent rehabilitation attempted. Valuable use of blood samples, and finally necropsy assessments, advances our understanding about the pathology common in live-stranded cetaceans.

Abstract

Capture myopathy (CM) is described in wild animals as a metabolic syndrome resulting from the extreme stress suffered during and after capture, handling, restraint, and transport. Although CM has been characterized in many species of cetaceans, descriptions of cardiac injury—an important component of this syndrome, and, according to previous authors, comparable to the existing human pathology so-called stress cardiomyopathy (SCMP)—are still rare. Therefore, the main aim of this report is to illustrate, for the first time, the biochemical analysis, and gross, histopathological, histochemical and immunohistochemical features of CM, and more specifically of the SCMP involved in this syndrome, caused by the live-stranding and consequent rehabilitation attempt, for a certain period of time, in a juvenile male Risso’s dolphin (Grampus griseus). The animal presented elevated values of creatine kinase, cardiac troponin I and blood urea nitrogen, with some variations during the rehabilitation period. Histologically, we detected vascular changes and acute degenerative lesions analogous to the ones observed in humans with SCMP. We consider this study to be an important contribution to the study of cetaceans since it could help in decision-making and treatment procedures during live-strandings and improve conservation efforts by reducing the mortality of these animals.

Skeletal and Cardiac Rhabdomyolysis in a Live-Stranded Neonatal Bryde's Whale With Fetal Distress

The main objective of wildlife forensic investigation is to recognize pathologic changes and cause of death. Even though it may not always be possible to determine the specific illness and/or etiology, the description and subsequent interpretation of the injuries provide an invaluable understanding of pathology in cetacean post-mortem investigations. Although pathological studies have been previously reported in various cetacean species, such descriptions of the infraorder Mysticeti remain rare. A live-stranded neonatal Bryde's whale (Balaenoptera edeni) which subsequently died soon after the stranding, was assessed by physical exam, blood examination, gross necropsy evaluation, histopathology, and immunohistochemistry. It presented with elevated serum levels of creatine kinase, cardiac troponin I, urea, and creatinine. Microscopically, we observed keratin spicules (squamous epithelial cells) and areas of atelectasis in the lungs. Acute degeneration in the myocytes and cardiomyocytes were comparable to the findings previously described in cases of capture myopathy in live-stranded cetaceans. Immunohistochemistry biomarkers such as myoglobin, fibrinogen, and troponin were analyzed. Skeletal and myocardial damage has been documented in several cetacean species. However, this is the first reported case of skeletal and cardiac rhabdomyolysis associated with live-stranding in a newborn Bryde's whale that suffered from fetal distress.

Stress cardiomyopathy in stranded cetaceans: a histological, histochemical and immunohistochemical study

BACKGROUND

Free-living cetaceans are exposed to a wide variety of stressful situations, including live stranding and interaction with human beings (capture myopathy), vessel strikes, and fishing activities (bycatch), which affect their wellbeing and potentially lead to stress cardiomyopathy (SCMP).

METHODS

Here, the authors aimed to characterise SCMP of stranded cetaceans as an injury resulting from extreme stress responses, based on pathological analyses (histological, histochemical and immunohistochemical). Specifically, the authors examined heart samples from 67 cetaceans found ashore (48 live strandings, seven dead from ship collision and 12 dead from bycatch) on the coast of Spain, more specifically in the Canary Islands from 2000 to 2016 and Andalusia from 2011 to 2014.

RESULTS

The microscopic findings were characterised by vascular changes, acute or subacute cardiac degenerative necrotic lesions, interstitial myoglobin globules, and infiltration of inflammatory cells. Immunohistochemically, cardiac troponin I, cardiac troponin C and myoglobin were depleted, along with fibrinogen being expressed in the degenerated/necrotic cardiomyocytes. A perivascular pattern was also identified and described in the damaged cardiomyocytes.

CONCLUSIONS

This study advances current knowledge about the pathologies of cetaceans and their implications on conserving this group of animals by reducing mortality and enhancing their treatment and subsequent rehabilitation to the marine environment.

The cardioprotective effects of diallyl trisulfide on diabetic rats with ex vivo induced ischemia/reperfusion injury

Diallyl trisulfide (DATS) is distinguished as the most potent polysulfide isolated from garlic. The aim of our study was to investigate effects of oral administration of DATS on healthy and diabetic rats, with special attention on heart function. Rats were randomly divided into four groups: CTRL (healthy rats), DATS (healthy rats treated with DATS), DM (diabetic rats), DM + DATS (diabetic rats treated with DATS). DATS (40 mg/kg of body weight) was administered every other day for 3 weeks, at the end of which rats underwent echocardiography, glycemic measurement and redox status assessment. Isolated rat hearts were subjected to 30 min global ischemia and 60 min reperfusion, after which heart tissue was counterstain with hematoxylin and eosin and cardiac Troponin T staining (cTnT), while expression of Bax, B cell lymphoma 2 (Bcl-2), caspase-3, caspase-9 and superoxide dismutase-2 were examined in the left ventricle. DATS treatment significantly reduced blood glucose levels of diabetic rats, and improved cardiac function recovery, diminished oxidation status, attenuated cardiac remodeling and inhibited myocardial apoptosis in healthy and diabetic rats. DATS treatment causes promising cardioprotective effects on ex vivo-induced ischemia/reperfusion (I/R) injury in diabetic and healthy rat heart probably mediated by inhibited myocardial apoptosis. Moreover, appropriate DATS consumption may provide potential co-therapy or prevention of hyperglycemia and various cardiac complications in rats with DM.

The Troponin-I fast skeletal muscle is reliable marker for the determination of vitality in the suicide hanging

Troponin I (TnI) is the inhibitory subunit of the troponin complex in the sarcomeric thin filament of striated muscle and plays a central role in the calcium regulation of contraction and relaxation. Vertebrate TnI has evolved into three isoforms encoded by three homologous genes: TNNI1 for slow skeletal muscle TnI, TNNI2 for fast skeletal muscle TnI and TNNI3 for cardiac TnI, which are expressed under muscle type-specific and developmental regulations in both the atrium and ventricle of the heart. Skeletal muscle TnI (both sTnI iso-forms) have been proposed as a sensitive and fast fiber-specific serum marker of skeletal muscle damage; fsTnI concentration in increased peripheral blood when fast twitch fibers were damaged. In our study we investigate if the 'Troponin I, fast skeletal muscle' can also be used as a reliable diagnostic tool in forensic practice, to perform differential diagnosis about vitality in suicide by hanging and simulated hanging (suspension of the victim after murder). We selected 8 women and 13 men, mean age 52.2 years, who died from suicidal hanging. The ligature material used for hanging was soft material in 11 cases and hard material in 10 cases. We chose cases as a control group of adults (n = 10; six women, four men, mean age 47.3 years) that died from opioid overdose (n = 2), car accident (n = 3) and sudden cardiac death (n = 5). Those deaths were characterized by their rapidity. To test the Anti-Troponin I fast skeletal muscle Antibody (Abcam clone-134,838), we used a case of a subject who died of myocardial infarction (timing infarct dated to 24-36 h prior to death). The reactions to Troponin I (namely the amount and extent of marker depletion) was scored for each section from 0 to -3: 0 = no loss of staining; -1 = minimal decrease in staining, compared to normally stained tissue; -2 = clear decrease in staining with some positivity (brown color) remaining; and -3 = no positive (brown) staining. The set of results obtained leads us to believe that the use of this antibody (Anti-Troponin I fast skeletal muscle antibody) is very promising to be able to make a certain differential diagnosis between antemortem and postmortem hangings. It should be emphasized that the present study seems to open new and promising horizons in the possibility to discriminate between suicidal hanging and simulated hanging (suspension of the victim after murder).

Diagnostic utility of cardiac troponin I in cats with hypertrophic cardiomyopathy

Background

Cardiac troponin I (cTnI) is useful for assessing hypertrophic cardiomyopathy (HCM) in cats.

Objective

To measure plasma cTnI concentrations in healthy cats and evaluate the clinical utility of cTnI in determining the severity of HCM.

Animals

Clinically healthy cats (n = 88) and cats with HCM (n = 93).

Methods

Multicenter prospective study. Cats with HCM, including hypertrophic obstructive cardiomyopathy at various stages, were diagnosed using echocardiography. Plasma cTnI concentrations were analyzed by a commercial laboratory. Receiver‐operating characteristic curve analysis was used to evaluate the accuracy of plasma cTnI concentrations to detect HCM.

Results

The median cTnI concentration was 0.027 ng/mL (interquartile range, 0.012‐0.048 ng/mL) in healthy cats. Concentrations were significantly higher in diseased cats than in healthy controls, and concentrations were significantly higher in cats with heart failure than in asymptomatic cats. A plasma cTnI concentration of 0.163 ng/mL had a sensitivity of 62.0% and specificity of 100% when used to distinguish normal cats from asymptomatic HCM cats without left atrial dilatation. A cutoff of 0.234 ng/mL had high sensitivity (95.0%) and specificity (77.8%) for assessing heart failure. The areas under the receiver‐operating characteristic curves were 0.85 and 0.93, respectively.

Conclusions and Clinical Importance

Increased cTnI concentrations reflect the severity of HCM. If other causes of cardiac injury are ruled out, plasma cTnI concentration may be useful for predicting the severity of HCM in cats.

Cardiac troponins: from myocardial infarction to chronic disease

Elucidation of the physiologically distinct subunits of troponin in 1973 greatly facilitated our understanding of cardiac contraction. Although troponins are expressed in both skeletal and cardiac muscle, there are isoforms of troponin I/T expressed selectively in the heart. By exploiting cardiac-restricted epitopes within these proteins, one of the most successful diagnostic tests to date has been developed: cardiac troponin (cTn) assays. For the past decade, cTn has been regarded as the gold-standard marker for acute myocardial necrosis: the pathological hallmark of acute myocardial infarction (AMI). Whilst cTn is the cornerstone for ruling-out AMI in patients presenting with a suspected acute coronary syndrome (ACS), elevated cTn is frequently observed in those without clinical signs indicative of AMI, often reflecting myocardial injury of 'unknown origin'. cTn is commonly elevated in acute non-ACS conditions, as well as in chronic diseases. It is unclear why these elevations occur; yet they cannot be ignored as cTn levels in chronically unwell patients are directly correlated to prognosis. Paradoxically, improvements in assay sensitivity have meant more differential diagnoses have to be considered due to decreased specificity, since cTn is now more easily detected in these non-ACS conditions. It is important to be aware cTn is highly specific for myocardial injury, which could be attributable to a myriad of underlying causes, emphasizing the notion that cTn is an organ-specific, not disease-specific biomarker. Furthermore, the ability to detect increased cTn using high-sensitivity assays following extreme exercise is disconcerting. It has been suggested troponin release can occur without cardiomyocyte necrosis, contradicting conventional dogma, emphasizing a need to understand the mechanisms of such release. This review discusses basic troponin biology, the physiology behind its detection in serum, its use in the diagnosis of AMI, and some key concepts and experimental evidence as to why cTn can be elevated in chronic diseases.

Follow-up of troponin I concentration in dogs with atrioventricular block and dual-chamber pacing in a case-matched study

BACKGROUND

Increased cardiac troponin I (cTnI) concentration has been reported in dogs with atrioventricular (AV) block before and shortly following pacemaker implantation. The role of AV dyssynchrony, age, or concurrent cardiac disease on cTnI concentration remains unknown.

OBJECTIVES

To investigate change in cTnI concentration following dual-chamber pacemaker implantation on short- and long-term follow-up and to compare cTnI values to a case-matched control group.

ANIMALS

Thirty-eight client-owned dogs with permanent AV block and 38 matched control dogs.

METHODS

Retrospective review of medical records. Pacemaker group consisted of dogs with AV block and dual-chamber pacing. Control group matched the study population in age and cardiac disease. cTnI was compared between pacemaker and control group on short- and long-term follow-up. Different lead types and influence of arrhythmia on cTnI were tested.

RESULTS

cTnI was high at presentation (median 0.66 ng/ml; range 0.03-18.6) and showed a significant reduction over time after pacemaker implantation (p < 0.0001). Median cTnI values were significantly different between pacemaker and control group on short-term (p = 0.0004; 0.11 ng/ml, range 0.03-1.36 versus 0.06 ng/ml, range 0.03-0.46), but not on long-term follow-up (p = 0.0547; 0.14 ng/ml, range 0.03-0.73 versus 0.07 ng/ml, range 0.03-0.46). Lead type and severity of arrhythmia did not show a significant correlation to cTnI concentration.

CONCLUSIONS

On long-term follow-up, cTnI remained mildly elevated in some of the pacemaker dogs but was not significantly different to the matched control group.

Immunohistochemical detection of early myocardial infarction: a systematic review

The postmortem diagnosis of early myocardial infarction is a challenge for forensic pathologists because the routine histology is neither specific. Many authors have suggested the use of the immunohistochemistry to fill the gaps in the histological diagnosis of early myocardial infarction. This review aims to analyse advances of immunohistochemical detection of early cardiac damage due to ischaemia. To this purpose, we reviewed experimental studies that investigated immunohistochemical markers and their estimated timing of expression. The review was performed according to specific inclusion and exclusion criteria, and a total of 23 studies assessing the immunohistochemical markers for the diagnosis and timing of early myocardial infarction were identified. The literature review highlights that the analysed markers are complement components, others being inflammatory mediators, cardiac cell proteins, plasma proteins, stress or hypoxia-induced factors and proteins associated with heart failure. All studies demonstrate the effectiveness of the tested markers in the early detection of myocardial infarction in both animal and human samples.

Early markers for myocardial ischemia and sudden cardiac death

The post-mortem diagnosis of acute myocardial ischemia remains a challenge for both clinical and forensic pathologists. We performed an experimental study (ligation of left anterior descending coronary artery in rats) in order to identify early markers of myocardial ischemia, to further apply to forensic and clinical pathology in cases of sudden cardiac death. Using immunohistochemistry, Western blots, and gene expression analyses, we investigated a number of markers, selected among those which are currently used in emergency departments to diagnose myocardial infarction and those which are under investigation in basic research and autopsy pathology studies on cardiovascular diseases. The study was performed on 44 adult male Lewis rats, assigned to three experimental groups: control, sham-operated, and operated. The durations of ischemia ranged between 5 min and 24 h. The investigated markers were troponins I and T, myoglobin, fibronectin, C5b-9, connexin 43 (dephosphorylated), JunB, cytochrome c, and TUNEL staining. The earliest expressions (≤30 min) were observed for connexin 43, JunB, and cytochrome c, followed by fibronectin (≤1 h), myoglobin (≤1 h), troponins I and T (≤1 h), TUNEL (≤1 h), and C5b-9 (≤2 h). By this investigation, we identified a panel of true early markers of myocardial ischemia and delineated their temporal evolution in expression by employing new technologies for gene expression analysis, in addition to traditional and routine methods (such as histology and immunohistochemistry). Moreover, for the first time in the autopsy pathology field, we identified, by immunohistochemistry, two very early markers of myocardial ischemia: dephosphorylated connexin 43 and JunB.

Cathepsin A inhibition attenuates myocardial infarction-induced heart failure on the functional and proteomic levels

Background

Myocardial infarction (MI) is a major cause of heart failure. The carboxypeptidase cathepsin A is a novel target in the treatment of cardiac failure. We aim to show that recently developed inhibitors of the protease cathepsin A attenuate post-MI heart failure.

Methods

Mice were subjected to permanent left anterior descending artery (LAD) ligation or sham operation. 24 h post–surgery, LAD-ligated animals were treated with daily doses of the cathepsin A inhibitor SAR1 or placebo. After 4 weeks, the three groups (sham, MI-placebo, MI-SAR1) were evaluated.

Results

Compared to sham-operated animals, placebo-treated mice showed significantly impaired cardiac function and increased plasma BNP levels. Cathepsin A inhibition prevented the increase of plasma BNP levels and displayed a trend towards improved cardiac functionality. Proteomic profiling was performed for the three groups (sham, MI-placebo, MI-SAR1). More than 100 proteins were significantly altered in placebo-treated LAD ligation compared to the sham operation, including known markers of cardiac failure as well as extracellular/matricellular proteins. This ensemble constitutes a proteome fingerprint of myocardial infarction induced by LAD ligation in mice. Cathepsin A inhibitor treatment normalized the marked increase of the muscle stress marker CA3 as well as of Igγ 2b and fatty acid synthase. For numerous further proteins, cathepsin A inhibition partially dampened the LAD ligation-induced proteome alterations.

Conclusions

Our proteomic and functional data suggest that cathepsin A inhibition has cardioprotective properties and support a beneficial effect of cathepsin A inhibition in the treatment of heart failure after myocardial infarction.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0907-8) contains supplementary material, which is available to authorized users.

Dityrosine as a marker of acute myocardial infarction? Experiments with the isolated Langendorff heart

The isolated Langendorff heart was used to evaluate dityrosine as a marker of acute myocardial infarctions. The animal model allowed the generation of local infarctions with defined survival times, as well as infarctions with and without reperfusion. The results showed that dityrosine, at least under the conditions of the animal model, occurs very shortly after early ischemia and infarctions, since positive staining results were already obtained after a survival time of only 5 min. Furthermore, it could be proved that the occurrence of dityrosine does not depend on a reperfusion of the ischemic muscle area and that there are no differences in the staining patterns of infarctions with and without reperfusion. Positive staining results for dityrosine in control hearts without infarctions had to be considered when evaluating the tissue samples of the study hearts. In part, the positive staining results of the control hearts seemed to be an artefact of the Langendorff system, easily identifiable by a distinctive staining pattern. Positive staining results in tissue samples of hearts that suffered from arrhythmia on the other hand implied that the occurrence of dityrosine is not specific for myocardial infarctions. Taking into account the results of previous works on human tissue samples, however, these findings did not question the use of dityrosine as a diagnostic tool; they simply showed that myocardial damage due to oxidative stress might occur under various pathologic conditions.

Clinical outcomes of adverse cardiovascular events in patients with acute dapsone poisoning

Objective

Adverse cardiovascular events (ACVEs) account for a large proportion of the morbidities and mortalities associated with drug overdose emergencies. However, there are no published reports regarding outcomes of ACVEs associated with acute dapsone poisoning. Here, the authors retrospectively analyzed ACVEs reported within 48 hours of treatment in patients with acute dapsone poisoning and assessed the significance of ACVEs as early predictors of mortality.

Methods

Sixty-one consecutive cases of acute dapsone poisoning that were diagnosed and treated at a regional emergency center between 2006 and 2014 were included in the study. An ACVE was defined as myocardial injury, shock, ventricular dysrhythmia, cardiac arrest, or any combination of these occurring within the first 48 hours of treatment for acute dapsone poisoning.

Results

Nineteen patients (31.1%) had evidence of myocardial injury (elevation of serum troponin-I level or electrocardiography signs of ischemia) after dapsone overdose, and there were a total of 19 ACVEs (31.1%), including one case of shock (1.6%). Fourteen patients (23.0%) died from pneumonia or multiple organ failure, and the incidence of ACVEs was significantly higher among non-survivors than among survivors (64.3% vs. 21.3%, P=0.006). ACVE was a significant predictor of mortality (odds ratio, 5.690; 95% confidence interval, 1.428 to 22.675; P=0.014).

Conclusion

The incidence of ACVE was significantly higher among patients who died after acute dapsone poisoning. ACVE is a significant predictor of mortality after dapsone overdose, and evidence of ACVE should be carefully sought in these patients.

Role of Cardiac Myocytes Heart Fatty Acid Binding Protein Depletion (H-FABP) in Early Myocardial Infarction in Human Heart (Autopsy Study)

BACKGROUND:

Many immunohistochemical markers have been used in the postmortem detection of early myocardial infarction.

AIM:

In the present study we examined the role of Heart-type fatty acid binding protein (H-FABP), in the detection of early myocardial infarction.

MATERIAL AND METHODS:

We obtained samples from 40 human autopsy hearts with/without histopathological signs of ischemia.

RESULTS:

All cases of definite and probable myocardial infarction showed a well-defined area of H-FABP depletion. All of the control cases showed strong H-FABP expression, except two markedly autolysed myocardial samples that showed affected antigenicity.

CONCLUSION:

Thus, we suggest H-FABP as being one of the valuable tools facing the problem of postmortem detection of early myocardial infarction/ischemia, but not in autolysis.

Immunohistochemical analysis of cardiac troponin inhibitor in an experimental model of acute myocardial infarction experimental model and in human tissues

Acute obstruction of coronary arteries leads to acute myocardial infarction (AMI), which causes unexpected death in humans. However, AMI cannot be easily detected in forensic examinations with traditional hematoxylin and eosin (H&E) staining. We analyzed whether cardiac troponin inhibitor (CTnI) could serve as a sensitive and specific early marker for diagnosing AMI in forensic medicine. We established an AMI model in rabbits by ligating the left ventricular branch and observed CTnI expression with immunohistochemistry after different ligation times. We found increased CTnI staining at the 0.5-h time point and depletion of CTnI staining with a 1-h ligation. The areas in which CTnI staining was depleted as seen with immunohistochemical analysis were consistent with the results of H&E staining. Next, human myocardium tissues from 30 persons who died from AMI and were subsequently examined in our forensic center were studied using immunohistochemistry with an antibody to human CTnI. Areas of infarction also showed depletion of CTnI staining. These findings suggested that immunohistochemical detection of CTnI is earlier, more sensitive, and myocardial tissue - specific as compared with H&E staining. CTnI may serve as an ideal marker for diagnosing AMI in forensic investigations.

NF-κB increased expression of 17β-hydroxysteroid dehydrogenase 4 promotes HepG2 proliferation via inactivating estradiol

Hepatocellular carcinoma (HCC) arises in a setting of chronic inflammation induced by inflammatory cytokines, such as nuclear factor-kappaB (NF-κB). HCC is a male-predominant cancer that can be attenuated by estradiol (E2) in vitro and in vivo. Although 17β-hydroxysteroid dehydrogenase 4 (HSD17B4) has been implicated as an estradiol-inactivating enzyme, and its promoter sequence contains two putative NF-κB elements: it is currently unknown whether HSD17B4 is the link between inflammation, estradiol and proliferation in hepatoma cells. In this study, HepG2 cells were used to investigate the role of HSD17B4 in the proliferation of liver cancer cells treated with the NF-κB activator, tumor necrosis factor-alpha (TNF-α), with the inhibitor of NF-κB activation, pyrrolidinedithiocarbamate (PDTC), or with a related specific siRNA. We demonstrated that the human HSD17B4 gene is a target for NF-κB activation in inflammation-stimulated HepG2 cells. HSD17B4 is up-regulated via the binding of activated NF-κB to the distal NF-κB-responsive element via TNF-α stimulation, which then promotes cell proliferation by decreasing the levels of E2 and enhancing the expression of interleukin 6 (IL-6), cyclin D1 and proliferating cell nuclear antigen (PCAN). These results from HepG2 cells are consistent with the observation that HSD17B4 is highly expressed and activated NF-κB is highly co-localized with the NF-κB-responsive element of HSD17B4 in liver tumor tissues from HCC patients. Our findings indicate for the first time that HSD17B4 plays an important role in aggravated HCC progression and provides a novel therapeutic target for HCC.

Clinical relevance of biomarkers in heart failure and cardiorenal syndrome: the role of natriuretic peptides and troponin

In recent years, numerous biomarkers have been studied in heart failure to improve diagnostic accuracy and identify patients at higher risk. The overall outcome remains fairish despite improvements in therapy, with mean survival after first hospitalization, around 5 years. We therefore need surrogate end points to better understand the pathogenetic mechanisms of the disease, including interplays with other organs. The kidney plays an important role in the initiation and progression of HF, and around one-third of patients with HF show some degree of renal dysfunction. In addition, treatment for HF often worsens renal function, consequently to hemodynamic and clinical improvement do not correspond an effective improvement in HF prognosis. Association between HF and renal impairment (RI) is now classified as cardiorenal syndrome (CRS) pointing out the bidirectional nature of this vicious circle leading to a mutual and progressive damage of both organs. The clinicians can rely on circulating biomarkers that give insights into the underlying pathogenetic mechanisms and help in risk stratification. Recently, a multimarker strategy including biomarker tool to traditional risk scores has been purposed and applied: Although each biomarker provided incremental outcome benefit, the combination of multiple biomarkers should offer the greatest improvement in risk prediction. Natriuretic peptides (NP) and cardiac troponins (TN) are the two biomarkers most studied in this setting, probably because of their organ-specific nature. However, both NP and TN cutoffs in presence of renal dysfunction need to be revised and discussed in relation to age, gender and stage of RI. In this context, the biomarkers are a unique opportunity to elucidate pathophysiological mechanisms, tailor clinical management to the single patient and improve outcomes. Specific studies about the exact role of biomarkers as in HF as in CRS should be planned and considered for future trials.