Cardioprotective O-GlcNAc signaling is elevated in murine female hearts via enhanced O-GlcNAc transferase activity.

The post-translational modification of intracellular proteins by O-linked ß-GlcNAc (O-GlcNAc) has emerged as a critical regulator of cardiac function. Enhanced O-GlcNAcylation activates cytoprotective pathways in cardiac models of ischemia-reperfusion (I/R) injury; however, the mechanisms underpinning O-GlcNAc cycling in response to I/R injury have not been comprehensively assessed. The cycling of O-GlcNAc is regulated by the collective efforts of two enzymes: O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA), which catalyze the addition and hydrolysis of O-GlcNAc, respectively. It has previously been shown that baseline heart physiology and pathophysiology are impacted by sex. Here, we hypothesized that sex differences in molecular signaling may target protein O-GlcNAcylation both basally and in ischemic hearts. To address this question, we subjected male and female WT murine hearts to ex vivo ischemia or I/R injury. We assessed hearts for protein O-GlcNAcylation, abundance of OGT, OGA, and glutamine:fructose-6-phosphate aminotransferase (GFAT2), activity of OGT and OGA, and UDP-GlcNAc levels. Our data demonstrate elevated O-GlcNAcylation in female hearts both basally and during ischemia. We show that OGT activity was enhanced in female hearts in all treatments, suggesting a mechanism for these observations. Furthermore, we found that ischemia led to reduced O-GlcNAcylation and OGT-specific activity. Our findings provide a foundation for understanding molecular mechanisms that regulate O-GlcNAcylation in the heart and highlight the importance of sex as a significant factor when assessing key regulatory events that control O-GlcNAc cycling. These data suggest the intriguing possibility that elevated O-GlcNAcylation in females contributes to reduced ischemic susceptibility.

A novel machine learning-based screening identifies statins as inhibitors of the calcium pump SERCA.

We report a novel small-molecule screening approach that combines data augmentation and machine learning to identify Food and Drug Administration (FDA)-approved drugs interacting with the calcium pump (Sarcoplasmic reticulum Ca2+-ATPase, SERCA) from skeletal (SERCA1a) and cardiac (SERCA2a) muscle. This approach uses information about small-molecule effectors to map and probe the chemical space of pharmacological targets, thus allowing to screen with high precision large databases of small molecules, including approved and investigational drugs. We chose SERCA because it plays a major role in the excitation-contraction-relaxation cycle in muscle and it represents a major target in both skeletal and cardiac muscle. The machine learning model predicted that SERCA1a and SERCA2a are pharmacological targets for seven statins, a group of FDA-approved 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors used in the clinic as lipid-lowering medications. We validated the machine learning predictions by using in vitro ATPase assays to show that several FDA-approved statins are partial inhibitors of SERCA1a and SERCA2a. Complementary atomistic simulations predict that these drugs bind to two different allosteric sites of the pump. Our findings suggest that SERCA-mediated Ca2+ transport may be targeted by some statins (e.g., atorvastatin), thus providing a molecular pathway to explain statin-associated toxicity reported in the literature. These studies show the applicability of data augmentation and machine learning-based screening as a general platform for the identification of off-target interactions and the applicability of this approach extends to drug discovery.

[The risk prediction value of paraquat poisoning dose, urine protein and myocardial enzymes].

Objective: To explore the value of paraquat (PQ) intake, urine protein and myocardial enzyme indexes in judging the prognosis of patients with acute PQ poisoning. Methods: From September to December 2021, all 201 patients with acute PQ poisoning admitted to Guangzhou Twelfth People's Hospital from January 2010 to December 2019 were selected as the research objects. Based on follow-up results 60 days after poisoning, the research objects were divided into survival group (n=78) and death group (n=123) . The differences in information about poisoning, treatment plan, PQ intake, urine protein, creatine kinase, creatine kinase isoenzyme, lactate dehydrogenase, and α-hydroxybutyrate dehydrogenase between the two groups of patients were compared and analyzed. Logistic regression and Cox regression were used to analyze the correlation between poisoning outcome and PQ intake, urine protein and myocardial enzymes. ROC curve and principal component analysis were used to explore high-efficiency indicators for predicting the outcome of acute PQ poisoning. Results: The PQ intake[50 (20, 100) ml], urine protein (total rank 15570.50) , creatine kinase[ (336.36±261.96) U/L], creatine kinase isoenzyme[ (43.91±43.74) U/L], lactate dehydrogenase [ (346.01±196.50) U/L], α-hydroxybutyrate dehydrogenase content[ (271.23±11.92) U/L] of patients in the death group were all higher than the survival group[15 (10, 20) ml, 4730.50, (187.78±178.06) U/L, (18.88±15.50) U/L, (190.92±60.50) U/L, (152.60±48.34) U/L, respectively] (P<0.05) . The outcome of acute PQ poisoning was positively correlated with PQ intake, urine protein, creatine kinase, creatine kinase isoenzyme, lactate dehydrogenase, and α-hydroxybutyrate dehydrogenase (P<0.05) . Multivariate logistic regression and multivariate Cox regression analysis showed that creatine kinase, creatine kinase isoenzyme, lactate dehydrogenase and α-hydroxybutyrate dehydrogenase was positively correlated with the prognosis of patients with acute PQ poisoning (P<0.05) . ROC curve analysis and principal component analysis showed that the combined indexes of PQ intake, urine protein and myocardial enzymes had the highest efficacy and weight in judging the prognosis of patients (AUC=0.91, weight coefficient=0.19, sensitivity=0.76, specificity=0.89) . When the combined score was ≥4, the probability of accurately predicting the death of patients was as high as 91% (positive predictive value=0.91) . Conclusion: PQ intake, urine protein combined with creatine kinase, creatine kinase isoenzyme, lactate dehydrogenase, and α-hydroxybutyrate dehydrogenase has high value in predicting the prognosis of patients with acute PQ poisoning.

Lethal Caspase-1/4-Dependent Injury Occurs in the First Minutes of Coronary Reperfusion and Requires Calpain Activity.

To study the relationship between caspase-1/4 and reperfusion injury, we measured infarct size (IS) in isolated mouse hearts undergoing 50 min global ischemia/2 h reperfusion. Starting VRT-043198 (VRT) at reperfusion halved IS. The pan-caspase inhibitor emricasan duplicated VRT's protection. IS in caspase-1/4-knockout hearts was similarly reduced, supporting the hypothesis that caspase-1/4 was VRT's only protective target. NLRC4 inflammasomes activate caspase-1. NLRC4 knockout hearts were not protected, eliminating NLRC4 as caspase-1/4's activator. The amount of protection that could be achieved by only suppressing caspase-1/4 activity was limited. In wild-type (WT) hearts, ischemic preconditioning (IPC) was as protective as caspase-1/4 inhibitors. Combining IPC and emricasan in these hearts or preconditioning caspase-1/4-knockout hearts produced an additive IS reduction, indicating that more protection could be achieved by combining treatments. We determined when caspase-1/4 exerted its lethal injury. Starting VRT after 10 min of reperfusion in WT hearts was no longer protective, revealing that caspase-1/4 inflicted its injury within the first 10 min of reperfusion. Ca++ influx at reperfusion might activate caspase-1/4. We tested whether Ca++-dependent soluble adenylyl cyclase (AC10) could be responsible. However, IS in AC10-/- hearts was not different from that in WT control hearts. Ca++-activated calpain has been implicated in reperfusion injury. Calpain could be releasing actin-bound procaspase-1 in cardiomyocytes, which would explain why caspase-1/4-related injury is confined to early reperfusion. The calpain inhibitor calpeptin duplicated emricasan's protection. Unlike IPC, adding calpain to emricasan offered no additional protection, suggesting that caspase-1/4 and calpain may share the same protective target.

The risk prediction value of paraquat poisoning dose, urine protein and myocardial enzymes / 中华劳动卫生职业病杂志

Objective: To explore the value of paraquat (PQ) intake, urine protein and myocardial enzyme indexes in judging the prognosis of patients with acute PQ poisoning. Methods: From September to December 2021, all 201 patients with acute PQ poisoning admitted to Guangzhou Twelfth People's Hospital from January 2010 to December 2019 were selected as the research objects. Based on follow-up results 60 days after poisoning, the research objects were divided into survival group (n=78) and death group (n=123) . The differences in information about poisoning, treatment plan, PQ intake, urine protein, creatine kinase, creatine kinase isoenzyme, lactate dehydrogenase, and α-hydroxybutyrate dehydrogenase between the two groups of patients were compared and analyzed. Logistic regression and Cox regression were used to analyze the correlation between poisoning outcome and PQ intake, urine protein and myocardial enzymes. ROC curve and principal component analysis were used to explore high-efficiency indicators for predicting the outcome of acute PQ poisoning. Results: The PQ intake[50 (20, 100) ml], urine protein (total rank 15570.50) , creatine kinase[ (336.36±261.96) U/L], creatine kinase isoenzyme[ (43.91±43.74) U/L], lactate dehydrogenase [ (346.01±196.50) U/L], α-hydroxybutyrate dehydrogenase content[ (271.23±11.92) U/L] of patients in the death group were all higher than the survival group[15 (10, 20) ml, 4730.50, (187.78±178.06) U/L, (18.88±15.50) U/L, (190.92±60.50) U/L, (152.60±48.34) U/L, respectively] (P<0.05) . The outcome of acute PQ poisoning was positively correlated with PQ intake, urine protein, creatine kinase, creatine kinase isoenzyme, lactate dehydrogenase, and α-hydroxybutyrate dehydrogenase (P<0.05) . Multivariate logistic regression and multivariate Cox regression analysis showed that creatine kinase, creatine kinase isoenzyme, lactate dehydrogenase and α-hydroxybutyrate dehydrogenase was positively correlated with the prognosis of patients with acute PQ poisoning (P<0.05) . ROC curve analysis and principal component analysis showed that the combined indexes of PQ intake, urine protein and myocardial enzymes had the highest efficacy and weight in judging the prognosis of patients (AUC=0.91, weight coefficient=0.19, sensitivity=0.76, specificity=0.89) . When the combined score was ≥4, the probability of accurately predicting the death of patients was as high as 91% (positive predictive value=0.91) . Conclusion: PQ intake, urine protein combined with creatine kinase, creatine kinase isoenzyme, lactate dehydrogenase, and α-hydroxybutyrate dehydrogenase has high value in predicting the prognosis of patients with acute PQ poisoning.

Knockout of TIGAR enhances myocardial phosphofructokinase activity and preserves diastolic function in heart failure.

Hypertension is an important risk factor in the pathogenesis of diastolic dysfunction. Growing evidence indicates that glucose metabolism plays an essential role in diastolic dysfunction. TP53-induced glycolysis and apoptosis regulator (TIGAR) has been shown to regulate glucose metabolism and heart failure (HF). In the present study, we investigated the role of TIGAR in diastolic function and cardiac fibrosis during pressure overload (PO)-induced HF. WT mice subjected to transverse aortic constriction (TAC), a commonly used method to induce diastolic dysfunction, exhibited diastolic dysfunction as evidenced by increased E/A ratio and E/E' ratio when compared to its sham controls. This was accompanied by increased cardiac interstitial fibrosis. In contrast, the knockout of TIGAR attenuated PO-induced diastolic dysfunction and interstitial fibrosis. Mechanistically, the levels of glucose transporter Glut-1, Glut-4, and key glycolytic enzyme phosphofructokinase 1 (PFK-1) were significantly elevated in TIGAR KO subjected to TAC as compared to that of WT mice. Knockout of TIGAR significantly increased fructose 2,6-bisphosphate levels and phosphofructokinase activity in mouse hearts. In addition, PO resulted in a significant increase in perivascular fibrosis and endothelial activation in the WT mice, but not in the TIGAR KO mice. Our present study suggests a necessary role of TIGAR-mediated glucose metabolism in PO-induced cardiac fibrosis and diastolic dysfunction.

Adenosine kinase (ADK) inhibition with ABT-702 induces ADK protein degradation and a distinct form of sustained cardioprotection.

Pharmacological inhibition of adenosine kinase (ADK), the major route of myocardial adenosine metabolism, can elicit acute cardioprotection against ischemia-reperfusion (IR) by increasing adenosine signaling. Here, we identified a novel, extended effect of the ADK inhibitor, ABT-702, on cardiac ADK protein longevity and investigated its impact on sustained adenosinergic cardioprotection. We found that ABT-702 treatment significantly reduced cardiac ADK protein content in mice 24-72 h after administration (IP or oral). ABT-702 did not alter ADK mRNA levels, but strongly diminished (ADK-L) isoform protein content through a proteasome-dependent mechanism. Langendorff perfusion experiments revealed that hearts from ABT-702-treated mice maintain higher adenosine release long after ABT-702 tissue elimination, accompanied by increased basal coronary flow (CF) and robust tolerance to IR. Sustained cardioprotection by ABT-702 did not involve increased nitric oxide synthase expression, but was completely dependent upon increased adenosine release in the delayed phase (24 h), as indicated by the loss of cardioprotection and CF increase upon perfusion of adenosine deaminase or adenosine receptor antagonist, 8-phenyltheophylline. Importantly, blocking adenosine receptor activity with theophylline during ABT-702 administration prevented ADK degradation, preserved late cardiac ADK activity, diminished CF increase and abolished delayed cardioprotection, indicating that early adenosine receptor signaling induces late ADK degradation to elicit sustained adenosine release. Together, these results indicate that ABT-702 induces a distinct form of delayed cardioprotection mediated by adenosine receptor-dependent, proteasomal degradation of cardiac ADK and enhanced adenosine signaling in the late phase. These findings suggest ADK protein stability may be pharmacologically targeted to achieve sustained adenosinergic cardioprotection.

Leptin Alleviates Inflammatory Response in Myocardial Ischemia Reperfusion Injury.

Objective: To investigate the role of leptin in regulating cell inflammation and protecting myocardium after myocardial ischemia-reperfusion injury in rats through signaling pathway at tissue and molecular protein levels. Methods: Healthy female SD rats were randomly divided into 4 groups, which were sham, I/R group, leptin low-dose intervention group, and high-dose intervention group (40 µg/kg and 80 µg/kg, respectively). Cardiac hemodynamics, myocardial enzymology, inflammatory indices, and pathological changes were observed. Western blot was used to observe the expression of PI3K, AKT, and NFκB protein by leptin. Results: Leptin can improve the hemodynamics of cardiac ischemia-reperfusion rats, improve the expression of myocardial enzymology, reduce the release of cardiac and serum inflammatory factors, increased PI3k, AKT, and NFκB expression, and reduce the occurrence of inflammation from the perspective of gross pathology, thus protecting the body. Conclusion: Leptin pretreatment can reduce MIRI injury, and the protective mechanism may be that leptin upregulates PI3K-AKT-NFκB expression in myocardial tissue to reduce inflammation and promote repair of I/R injury.

Consumption of combined fructose and sucrose diet exacerbates oxidative stress, hypertrophy and CaMKIIδ oxidation in hearts from rats with metabolic syndrome.

The prevalence of the metabolic syndrome (MetS) and its cardiac comorbidities as cardiac hypertrophy (CH) have increased considerably due to the high consumption of carbohydrates, such as sucrose and/or fructose. We compared the effects of sucrose (S), fructose (F) and their combination (S + F) on the development of MetS in weaned male Wistar rats and established the relationship between the consumption of these sugars and the degree of cardiac CH development, oxidative stress (OS) and Calcium/calmodulin-dependent protein kinase type II subunit delta oxidation (ox-CaMKIIδ). 12 weeks after the beginning of treatments with S, F or S + F, arterial pressure was measured and 8 weeks later (to complete 20 weeks) the animals were sacrificed and blood samples, visceral adipose tissue and hearts were obtained. Biochemical parameters were determined in serum and cardiac tissue to evaluate the development of MetS and OS. To evaluate CH, atrial natriuretic peptide (ANP), CaMKIIδ and ox-CaMKIIδ were determined by western blot and histological studies were performed in cardiac tissue. Our data showed that chronic consumption of S + F exacerbates MetS-induced CH which is related with a higher OS and ox-CaMKIIδ.

Colchicine Ameliorates 5-Fluorouracil-Induced Cardiotoxicity in Rats.

Background and Objective. 5-Fluorouracil is one of the most common chemotherapeutic agents used in the treatment of solid tumors. 5-Fluorouracil-associated cardiotoxicity is the second cause of cardiotoxicity induced by chemotherapeutic drugs after anthracyclines. Colchicine is a strong anti-inflammatory drug used to prevent and treat acute gout and treat familial Mediterranean fever. And also, its protective effects on cardiovascular disease have been reported in various studies. The current study is aimed at appraising the effect of colchicine on 5-fluorouracil-induced cardiotoxicity in rats. Methods. Twenty male Wistar rats were divided into four groups as follows: control, 5-fluorouracil, colchicine (5 mg/kg), and 5-fluorouracil+5 mg/kg colchicine. Cardiotoxicity was induced with an intraperitoneal injection of a single dose of 5-fluorouracil (100 mg/kg). The control group received normal saline, and the treatment groups received colchicine with an intraperitoneal injection for 14 days. Findings. 5-Fluorouracil resulted in significant cardiotoxicity represented by an increase in cardiac enzymes, malondialdehyde levels, cyclooxygenase-2 and tumor necrosis factor-alpha expression, cardiac enzymes, and histopathological degenerations. 5-Fluorouracil treatment also decreased body weight, total antioxidant capacity and catalase values, blood cells, and hemoglobin levels. In addition, 5-fluorouracil disrupted electrocardiographic parameters, including increased elevation in the ST segment and increased QRS duration. Treatment with colchicine reduced oxidative stress, cardiac enzymes, histopathological degenerations, and cyclooxygenase-2 expression in cardiac tissue, improved electrocardiographic disorders, and enhanced the number of blood cells and total antioxidant capacity levels. Moreover, body weight loss was hampered after treatment with colchicine. Our results demonstrated that treatment with colchicine significantly improved cardiotoxicity induced by 5-fluorouracil in rats.

Sex- and age-specific regulation of ACE2: Insights into severe COVID-19 susceptibility.

Aged males disproportionately succumb to increased COVID-19 severity, hospitalization, and mortality compared to females. Angiotensin-converting enzyme 2 (ACE2) and transmembrane protease, serine 2 (TMPRSS2) facilitate SARS-CoV-2 viral entry and may have sexually dimorphic regulation. As viral load dictates disease severity, we investigated the expression, protein levels, and activity of ACE2 and TMPRSS2. Our data reveal that aged males have elevated ACE2 in both mice and humans across organs. We report the first comparative study comprehensively investigating the impact of sex and age in murine and human levels of ACE2 and TMPRSS2, to begin to elucidate the sex bias in COVID-19 severity.

The modulation of SIRT1 and SIRT3 by natural compounds as a therapeutic target in doxorubicin-induced cardiotoxicity: A review.

Doxorubicin (DOX) is a potent antitumor agent with a broad spectrum of activity; however, irreversible cardiotoxicity resulting from DOX treatment is a major issue that limits its therapeutic use. Sirtuins (SIRTs) play an essential role in several physiological and pathological processes including oxidative stress, apoptosis, and inflammation. It has been reported that SIRT1 and SIRT3 can act as a protective molecular against DOX-induced myocardial injury through targeting numerous signaling pathways. Several natural compounds (NCs), such as resveratrol, sesamin, and berberine, with antioxidative, anti-inflammation, and antiapoptotic effects were evaluated for their potential to suppress the cardiotoxicity induced by DOX via targeting SIRT1 and SIRT3. Numerous NCs exerted their therapeutic effects on DOX-mediated cardiac damage via targeting different signaling pathways, including SIRT1/LKB1/AMPK, SIRT1/PGC-1α, SIRT1/NLRP3, and SIRT3/FoxO. SIRT3 also ameliorates cardiotoxicity by enhancing mitochondrial fusion.

Indoleamine 2,3-dioxygenase (IDO)-1 and IDO-2 activity and severe course of COVID-19.

COVID-19 is a pandemic with high morbidity and mortality. In an autopsy cohort of COVID-19 patients, we found extensive accumulation of the tryptophan degradation products 3-hydroxy-anthranilic acid and quinolinic acid in the lungs, heart, and brain. This was not related to the expression of the tryptophan-catabolizing indoleamine 2,3-dioxygenase (IDO)-1, but rather to that of its isoform IDO-2, which otherwise is expressed rarely. Bioavailability of tryptophan is an absolute requirement for proper cell functioning and synthesis of hormones, whereas its degradation products can cause cell death. Markers of apoptosis and severe cellular stress were associated with IDO-2 expression in large areas of lung and heart tissue, whereas affected areas in brain were more restricted. Analyses of tissue, cerebrospinal fluid, and sequential plasma samples indicate early initiation of the kynurenine/aryl-hydrocarbon receptor/IDO-2 axis as a positive feedback loop, potentially leading to severe COVID-19 pathology. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Ubiquinol-cytochrome c reductase core protein 1 contributes to cardiac tolerance to acute exhaustive exercise.

Ubiquinol-cytochrome c reductase core protein 1 (UQCRC1) is an indispensable component of mitochondrial complex III. It plays a key role in cardioprotection and maintaining mitochondrion function. However, the exact role of UQCRC1 in maintaining cardiac function has not been reported by in vivo models. Also, the exact biological functions of UQCRC1 are far from fully understood. UQCRC1+/- mice had decreased both mRNA and protein expression of UQCRC1 in the left ventricular myocardia, and these mice had reduced tolerance to acute exhaustive exercise including decreased time and distance with higher apoptosis rate, higher expression level of cleaved CASPASE 3, and higher ratio of cleaved PARP1 to full-length PARP1. Moreover, UQCRC1 knockdown led to increased LV interventricular septal thicknesses both at systole and diastole, as well as decreased LV volume both at end-systole and end-diastole. Finally, UQCRC1 gene disruption resulted in mitochondrial vacuolation, fibril disarrangement, and more severe morphological and structural changes in mitochondria after acute exhaustive exercise. In conclusion, UQCRC1 contributes to cardiac tolerance to acute exhaustive exercise in mice, and it may be an essential component of complex III, playing a crucial role in maintaining cardiac functions.

Physiological and pathological roles of protein kinase A in the heart.

Protein kinase A (PKA) is a central regulator of cardiac performance and morphology. Myocardial PKA activation is induced by a variety of hormones, neurotransmitters, and stress signals, most notably catecholamines secreted by the sympathetic nervous system. Catecholamines bind ß-adrenergic receptors to stimulate cAMP-dependent PKA activation in cardiomyocytes. Elevated PKA activity enhances Ca2+ cycling and increases cardiac muscle contractility. Dynamic control of PKA is essential for cardiac homeostasis, as dysregulation of PKA signalling is associated with a broad range of heart diseases. Specifically, abnormal PKA activation or inactivation contributes to the pathogenesis of myocardial ischaemia, hypertrophy, heart failure, as well as diabetic, takotsubo, or anthracycline cardiomyopathies. PKA may also determine sex-dependent differences in contractile function and heart disease predisposition. Here, we describe the recent advances regarding the roles of PKA in cardiac physiology and pathology, highlighting previous study limitations and future research directions. Moreover, we discuss the therapeutic strategies and molecular mechanisms associated with cardiac PKA biology. In summary, PKA could serve as a promising drug target for cardioprotection. Depending on disease types and mechanisms, therapeutic intervention may require either inhibition or activation of PKA. Therefore, specific PKA inhibitors or activators may represent valuable drug candidates for the treatment of heart diseases.

Selective Cdk9 inhibition resolves neutrophilic inflammation and enhances cardiac regeneration in larval zebrafish.

Sustained neutrophilic inflammation is detrimental for cardiac repair and associated with adverse outcomes following myocardial infarction (MI). An attractive therapeutic strategy to treat MI is to reduce or remove infiltrating neutrophils to promote downstream reparative mechanisms. CDK9 inhibitor compounds enhance the resolution of neutrophilic inflammation; however, their effects on cardiac repair/regeneration are unknown. We have devised a cardiac injury model to investigate inflammatory and regenerative responses in larval zebrafish using heartbeat-synchronised light-sheet fluorescence microscopy. We used this model to test two clinically approved CDK9 inhibitors, AT7519 and flavopiridol, examining their effects on neutrophils, macrophages and cardiomyocyte regeneration. We found that AT7519 and flavopiridol resolve neutrophil infiltration by inducing reverse migration from the cardiac lesion. Although continuous exposure to AT7519 or flavopiridol caused adverse phenotypes, transient treatment accelerated neutrophil resolution while avoiding these effects. Transient treatment with AT7519, but not flavopiridol, augmented wound-associated macrophage polarisation, which enhanced macrophage-dependent cardiomyocyte number expansion and the rate of myocardial wound closure. Using cdk9-/- knockout mutants, we showed that AT7519 is a selective CDK9 inhibitor, revealing the potential of such treatments to promote cardiac repair/regeneration.

Impacts of Yangxin decoction on the expressions of MMP-9, CaN, NFAT3 and GATA4 in myocardial tissue of rats with chronic heart failure.

To investigate the impacts of Yangxin decoction on the expressions of matrix metalloproteinase 9 (MMP-9), calcineurin (CaN), T cell activated nuclear factor 3 (NFAT3) and zinc finger transcription factor 4 (GATA4) in myocardial tissue of rats with chronic heart failure (CHF). 50 healthy SD rats were randomly divided into the normal control group (n = 10) and the operation group (n = 40). After successful modeling, the rats were randomly divided into 4 groups. And they were treated with Yangxin decoctions of low concentration (1.5 g/kg), medium concentration (2.5 g/kg), high concentration (3.5 g/kg) and distilled water (for 4 weeks). The LVSP, SAP, DAP and LVEDP in Yangxin decoction treatment groups were significantly superior to the model group. The LVEF, LVIDd and LVIDs in Yangxin decoction treatment groups were significantly superior to the model group. The activity of CaN in each group treated with Yangxin decoction was significantly lower than that in the model group. The expression levels of MMP-9, NFAT3, GATA4 protein in each group treated with Yangxin decoction were significantly lower than that in the model group.. Yangxin decoction can significantly improve the cardiac function, reduce CaN activity, decrease the expression levels of MMP-9, NFAT3 and GATA4, inhibit CaN/NFAT3 signaling pathway, increase myocardial remodeling and protect myocardial tissue in rats with CHF.

Association of Myocardial Enzyme Abnormality with Clinical Outcomes of Patients with COVID-19: A Retrospective Study.

BACKGROUND: It has been observed that COVID-19 may cause myocardial damage, but there are few detailed reports on myocardial enzyme abnormalities. METHODS: In this retrospective study, we analyzed data from 157 consecutive laboratory-confirmed and hospitalized COVID-19 patients from Wuhan. We collected information on demographic and clinical characteristics, laboratory findings, and clinical outcomes. Logistic regression analysis was used to explore the risk factors associated with the severity of COVID-19. The association between myocardial enzyme abnormalities and the mortality was also investigated. RESULTS: The mortality in abnormal myocardial enzyme group was obviously higher than the normal group (P < 0.001). The majority of patients (n = 72, 97.3%) with normal cardiac enzyme group were of the common novel coronavirus pneumonia (NCP) type, whereas half of the patients with cardiac enzyme abnormalities (n = 40, 48.2%) developed critical and severe NCP type. The multivariable logistic regression analysis indicated that COVID-19 patients with increasing age (P = 0.035), higher levels of CRP (P = 0.038), and TNI (P = 0.036) were associated with increased death than other patients. CONCLUSIONS: Myocardial enzyme abnormality and myocardial injury were associated with the severity and fatal outcomes of COVID-19. Clinicians should pay attention to the markers of myocardial injury in COVID-19 patients, especially those with older age, comorbidities, and inflammation.

Structure, Function, and Thermodynamics of Lactate Dehydrogenases from Humans and the Malaria Parasite P. falciparum.

Temperature adaptation is ubiquitous among all living organisms, yet the molecular basis for this process remains poorly understood. It can be assumed that for parasite-host systems, the same enzymes found in both organisms respond to the same selection factor (human body temperature) with similar structural changes. Herein, we report the existence of a reversible temperature-dependent structural transition for the glycolytic enzyme lactate dehydrogenase (LDH) from the malaria parasite Plasmodium falciparum (pfLDH) and human heart (hhLDH) occurring in the temperature range of human fever. This transition is observed for LDHs from psychrophiles, mesophiles, and moderate thermophiles in their operating temperature range. Thermodynamic analysis reveals unique thermodynamic signatures of the LDH-substrate complexes defining a specific temperature range to which human LDH is adapted and parasite LDH is not, despite their common mesophilic nature. The results of spectroscopic analysis combined with the available crystallographic data reveal the existence of an active center within pfLDH that imparts psychrophilic structural properties to the enzyme. This center consists of two pockets, one formed by the five amino acids (5AA insert) within the substrate specificity loop and the other by the active site, that mutually regulate one another in response to temperature and induce structural and functional changes in the Michaelis complex. Our findings pave the way toward a new strategy for malaria treatments and drug design using therapeutic agents that inactivate malarial LDH selectively at a specific temperature range of the cyclic malaria paroxysm.