Relationship between dry skin and pressure injury in older patients: A multicentre cross-sectional survey in China.

Dry skin and pressure injuries in older persons have become global health care problems. This was a multicentre, prospective cross-sectional study in 44 hospitals and 8 long term care institutions from 20 provinces, autonomous regions and municipalities in China and aimed to explore the relationship between the two skin problems in older patients. We mainly found 11 602 cases with dry skin and 1076 cases with pressure injuries in a total of 33 769 valid participants. The overall prevalence of dry skin and pressure injuries was 34.4% (95% confidence interval [CI] 33.9-34.9) and 3.1% (95% CI 2.9-3.3). Stage 2+ pressure injuries were the most (32.9%), followed by stage 1 (32.4%). The patients with dry skin had more pressure injuries than ones without dry skin (50.0% vs 33.9%). The patients with very severe and severe dry skin had more pressure injury risk (OR 2.22 and 1.90) and more stage 2+ pressure injury risk (OR 2.83 and 1.63). Other nine predictors associated with overall pressure injuries and stage 2+ pressure injuries. The area under receiver operating characteristic (ROC) curve of the predictive models of overall pressure injuries and stage 2+ pressure injuries were 0.89 (95% CI 0.88-0.90) and 0.91 (95% CI 0.90-0.92), respectively.

Novel in vivo and in vitro mechanisms of positive inotropic effect of atractylodin.

This study was to investigate the inotropic effect of atractylodin and its underlying mechanism. The cardiac pressure-volume loop (P-V loop), Langendroff-perfused isolated rat heart, patch-clamp, Ca2+ transient and western blot techniques were used. The results demonstrated that atractylodin (3 mg/kg, ip) remarkably increased the left ventricular stroke work, cardiac output, stroke volume, heart rate, ejection fraction, end-systolic pressure, peak rates of rise and fall of left ventricular pressures (+dP/dtmax , -dP/dtmax ), the slopes of end-systolic pressure-volume relationship (also named as end-systolic elastance, Ees) and reducing end-systolic volume and end-diastolic volume in the in vivo rat study. Also, atractylodin (3 mg/kg, ip) significantly decreased diastolic blood pressure and the arterial elastance (Ea) without significant systolic blood pressure change. In addition, atractylodin (0.1, 1, 10 µmol/L) also increased the isolated rat heart left ventricular developed pressure which is the difference between the systolic and diastolic pressure in non-pacing and pacing modes. Furthermore, JMV-2959 (1 µmol/L), a ghrelin receptor unbiased antagonist, blocked the increased left ventricular developed pressure of atractylodin in isolated rat hearts. Finally, atractylodin (5 µmol/L) increased the amplitude of Ca2+ transient by enhancing SERCA2a activity, the sarcoplasmic reticulum Ca2+ content and the phosphorylation of phospholamban at 16-serine. These results demonstrated that atractylodin had a positive inotropic effect by enhancing SERCA2a activity which might be mediated by acting ghrelin receptor in myocardium. In conclusion, atractylodin which had the positive inotropic effect and decreased diastolic blood pressure might serve as an agent for the treatment of heart failure in clinical settings.

Increased sarcoplasmic/endoplasmic reticulum calcium ATPase 2a activity underlies the mechanism of the positive inotropic effect of ivabradine.

NEW FINDINGS: What is the central question of this study? The therapeutic effect of ivabradine on patients with chronic heart failure and chronic stable angina pectoris is mediated through a reduction in heart rate: what are the haemodynamic characteristics and the mechanism of the inotropic effect? What is the main finding and its importance? Ivabradine has a positive inotropic effect and lowers the heart rate both in vivo and in vitro. These effects are likely mediated by ivabradine's significant increase of the fast component rate constant mediated by sarcoplasmic/endoplasmic reticulum calcium ATPase 2a and decrease of the slow component rate constant that is mediated by the Na+ /Ca2+ exchanger and sarcolemmal Ca2+ -ATPase during the Ca2+ transient decay phase. ABSTRACT: Ivabradine's therapeutic effect is mediated by a reduction of the heart rate; however, its haemodynamic characteristics and the mechanism of its inotropic effect are poorly understood. We aimed to investigate the positive inotropic effect of ivabradine and its underlying mechanism. The results demonstrated that ivabradine increased the positive inotropy of the rat heart in vivo by increasing the stroke work, cardiac output, stroke volume, end-diastolic volume, end-systolic pressure, ejection fraction, ±dP/dtmax , left ventricular end-systolic elastance and systolic blood pressure without altering the diastolic blood pressure and arterial elastance. This inotropic effect was observed in both non-paced and paced rat isolated heart. Ivabradine increased the Ca2+ transient amplitude and the reuptake rates of sarcoplasmic/endoplasmic reticulum calcium ATPase 2a (SERCA2a), lowered the diastolic Ca2+ level and suppressed the combined extrusion rate of the Na+ /Ca2+ exchanger and the sarcolemmal Ca2+ -ATPase. In addition, ivabradine widened the action potential duration, hyperpolarized the resting membrane potential, increased sarcoplasmic reticulum Ca2+ content and reduced Ca2+ leak. Overall, ivabradine had a positive inotropic effect brought about by enhanced SERCA2a activity, which might be mediated by increased phospholamban phosphorylation. The positive inotropic effect along with the lowered heart rate underlies ivabradine's therapeutic effect in heart failure.

Liguzinediol Enhances the Inotropic Effect of Rat Hearts via Inhibition of Protein Phosphatase (PP1 and PP2A) Activities.

It has been demonstrated that liguzinediol (2,5-dihydroxymethyl-3,6-dimethylpyrazine, LZDO), a derivative of ligustrazine from Ligusticum wallichii Franch, exerts positive inotropy in isolated rat heart mediated by the sarcoplasmic reticulum Ca-ATPase (SERCA2a). Here, we further explore the underlying mechanism of the positive inotropic effect of LZDO in rat hearts. In vivo and ex vivo rat heart experiments, biochemistry, and Western blot techniques were used to analyze the rat heart contractility, and SERCA2a activity, phospholamban (PLB) phosphorylation, and protein phosphatase (PP1 and PP2A) activities in rat left ventricular myocytes, respectively. LZDO (20 mg/kg) significantly increased the inotropy of rat heart in vivo. In isolated rat heart experiments, LZDO (100 µM) restored the decreased inotropy induced by caffeine (0.5 mM); however, calyculin A (4 nM), an inhibitor of PP1 and PP2A, eliminated the inotropic effect of LZDO (100 µM). Moreover, LZDO (1, 10, and 100 µM) significantly enhanced SERCA2a activity and increased the levels of phosphorylated PLB on both serine-16 (Ser-16) and threonine-17 (Thr-17). In addition, LZDO (100 µM) significantly inhibited the activities of PP1 and PP2A. The positive inotropic effects of LZDO on in vivo and ex vivo rat hearts seem to be mediated through inhibition of PP1/PP2A, which may suppress dephosphorylated PLB and enhance SERCA2a activity. LZDO may prove effective in treating heart failure in clinical settings based on its unique biological mechanism.

Arrhythmogenic mechanisms of interleukin-6 combination with hydroxychloroquine and azithromycin in inflammatory diseases.

Inflammatory diseases including COVID-19 are associated with a cytokine storm characterized by high interleukin-6 (IL-6) titers. In particular, while recent studies examined COVID-19 associated arrhythmic risks from cardiac injury and/or from pharmacotherapy such as the combination of azithromycin (AZM) and hydroxychloroquine (HCQ), the role of IL-6 per se in increasing the arrhythmic risk remains poorly understood. The objective is to elucidate the electrophysiological basis of inflammation-associated arrhythmic risk in the presence of AZM and HCQ. IL-6, AZM and HCQ were concomitantly administered to guinea pigs in-vivo and in-vitro. Electrocardiograms, action potentials and ion-currents were analyzed. IL-6 alone or the combination AZM + HCQ induced mild to moderate reduction in heart rate, PR-interval and corrected QT (QTc) in-vivo and in-vitro. Notably, IL-6 alone was more potent than the combination of the two drugs in reducing heart rate, increasing PR-interval and QTc. In addition, the in-vivo or in-vitro combination of IL-6 + AZM + HCQ caused severe bradycardia, conduction abnormalities, QTc prolongation and asystole. These electrocardiographic abnormalities were attenuated in-vivo by tocilizumab (TCZ), a monoclonal antibody against IL-6 receptor, and are due in part to the prolongation of action potential duration and selective inhibition of Na+, Ca2+ and K+ currents. Inflammation confers greater risk for arrhythmia than the drug combination therapy. As such, in the setting of elevated IL-6 during inflammation caution must be taken when co-administering drugs known to predispose to fatal arrhythmias and TCZ could be an important player as a novel anti-arrhythmic agent. Thus, identifying inflammation as a critical culprit is essential for proper management.

Interleukin-6 Elevation Is a Key Pathogenic Factor Underlying COVID-19-Associated Heart Rate-Corrected QT Interval Prolongation.

Background: Heart rate-corrected QT interval (QTc) prolongation is prevalent in patients with severe coronavirus disease 2019 (COVID-19) and is associated with poor outcomes. Recent evidence suggests that the exaggerated host immune-inflammatory response characterizing the disease, specifically interleukin-6 (IL-6) increase, may have an important role, possibly via direct effects on cardiac electrophysiology. The aim of this study was to dissect the short-term discrete impact of IL-6 elevation on QTc in patients with severe COVID-19 infection and explore the underlying mechanisms. Methods: We investigated the following mechanisms: (1) the QTc duration in patients with COVID-19 during the active phase and recovery, and its association with C-reactive protein (CRP) and IL-6 levels; (2) the acute impact of IL-6 administration on QTc in an in vivo guinea pig model; and (3) the electrophysiological effects of IL-6 on ventricular myocytes in vitro. Results: In patients with active severe COVID-19 and elevated IL-6 levels, regardless of acute myocardial injury/strain and concomitant QT-prolonging risk factors, QTc was significantly prolonged and rapidly normalized in correlation with IL-6 decrease. The direct administration of IL-6 in an in vivo guinea pig model acutely prolongs QTc duration. Moreover, ventricular myocytes incubated in vitro with IL-6 show evident prolongation in the action potential, along with significant inhibition in the rapid delayed rectifier potassium current (IKr). Conclusion: For the first time, we demonstrated that in severe COVID-19, systemic inflammatory activation can per se promote QTc prolongation via IL-6 elevation, leading to ventricular electric remodeling. Despite being transitory, such modifications may significantly contribute to arrhythmic events and associated poor outcomes in COVID-19. These findings provide a further rationale for current anti-inflammatory treatments for COVID-19, including IL-6-targeted therapies.

Bay 60-7550, a PDE2 inhibitor, exerts positive inotropic effect of rat heart by increasing PKA-mediated phosphorylation of phospholamban.

This study investigated the hemodynamic effect of Bay 60-7550, a phosphodiesterase type 2 (PDE2) inhibitor, in healthy rat hearts both in vivo and ex vivo and its underlying mechanisms. In vivo rat left ventricular pressure-volume loop, Langendorff isolated rat heart, Ca2+ transient of left ventricular myocyte and Western blot experiments were used in this study. The results demonstrated that Bay 60-7550 (1.5 mg/kg, i. p.) increased the in vivo rat heart contractility by enhancing stroke work, cardiac output, stroke volume, end-diastolic volume, heart rate, and ejection fraction. The simultaneous aortic pressure recording indicated that the systolic blood pressure was increased and diastolic blood pressure was decreased by Bay 60-7550. Also, the arterial elastance which is proportional to the peripheral vessel resistance was significantly decreased. Bay 60-7550 (0.001, 0.01, 0.1, 1 µmol/l) also enhanced the left ventricular development pressure in non-paced and paced modes with a decrease of heart rate in non-paced model. Bay 60-7550 (1 µmol/l) increased SERCA2a activity and SR Ca2+ content and reduced SR Ca2+ leak rate. Furthermore, Bay 60-7550 (0.1 µmol/l) increased the phosphorylation of phospholamban at 16-serine without significantly changing the phosphorylation levels of phospholamban at 17-threonine and RyR2. Bay 60-7550 increased the rat heart contractility and reduced peripheral arterial resistance may be mediated by increasing the phosphorylation of phospholamban and dilating peripheral vessels. PDE2 inhibitors which result in a positive inotropic effect and a decrease in peripheral resistance might serve as a target for developing agents for the treatment of heart failure in clinical settings.

Rolipram, a PDE4 Inhibitor, Enhances the Inotropic Effect of Rat Heart by Activating SERCA2a.

This study was designed to investigate the hemodynamic effect of rolipram, a phosphodiesterase type 4 (PDE4) inhibitor, in normal rat hearts both in vivo and in vitro and its underlying mechanism. The pressure-volume loop, isolated heart, and Ca2+ transients triggered by field stimulation or caffeine were used to analyze the hemodynamic mechanism of rolipram. The results demonstrated that rolipram (3 mg/kg, ip) significantly increased the in vivo rat heart contractility by enhancing stroke work, cardiac output, stroke volume, end-systolic volume, end-diastolic volume, end-systolic pressure, heart rate, ejection fraction, peak rate of rise of left pressure (+dp/dtmax), the slopes of end-systolic pressure-volume relationship (slope of ESPVR) named as left ventricular end-systolic elastance, and reduced the slopes of end-diastolic pressure-volume relationship (slope of EDPVR). Meanwhile, the systolic blood pressure, diastolic blood pressure, and pulse pressure were significantly enhanced by rolipram. Also, rolipram deviated normal ventricular-arterial coupling without changing the arterial elastance. Furthermore, rolipram (0.1, 1, 10 µM) also exerted positive inotropic effect in isolated rat hearts by increasing the left ventricular development pressure, and +dp/dtmax in non-paced and paced modes. Rolipram (10 µM) increased the SERCA2a activity, Ca2+ content, and Ca2+ leak rate without changing diastolic Ca2+ level. Rolipram had significant positive inotropic effect with less effect on peripheral vascular elastance and its underlying mechanism was mediated by increasing SERCA2a activity. PDE4 inhibition by rolipram resulted in a positive inotropic effect and might serve as a target for developing agents for the treatment of heart failure in clinical settings.

Electrophysiologic Studies on the Risks and Potential Mechanism Underlying the Proarrhythmic Nature of Azithromycin.

The mechanisms underlying arrhythmia induced by the clinical use of azithromycin are poorly understood. We aimed to investigate the proarrhythmic effects of azithromycin using electrocardiogram (ECG) and ion channel models. In vivo and in vitro guinea pig ECG and current and voltage clamp recordings were carried out. Azithromycin at 114.6 mg/kg (three times the clinically relevant dose) reduced heart rate (HR) and prolonged the PR, QRS and rate-corrected QT (QTc) intervals of guinea pig ECG in vivo. In vitro technique revealed that azithromycin at 207.5 and 415 mg/L [five and ten times clinically relevant concentration (CRC)] reduced HR and prolonged the PR, QRS and QTc intervals in the isolated guinea pig heart ECG. Both arrhythmias presented bradyarrhythmic features, mainly with reduced HR and prolonged PR interval. Action potential analysis from the guinea pig cardiomyocytes indicated that azithromycin at 830 mg/L (20 times CRC) significantly prolonged the action potential durations at 50% (APD50) and 90% (APD90) of full repolarization levels with a rectangular pattern. Azithromycin significantly suppressed the L-type Ca2+ and Na+ currents from the left ventricular myocytes of guinea pig at 50% inhibiting concentrations (IC50) of 942.5 ± 68.4 mg/L (22.7 times CRC) and 1123.0 ± 87.7 mg/L (27.1 times CRC), respectively. However, azithromycin at 50 times CRC (2075 mg/L) inhibited IKr current at an inhibition rate of 30.99 ± 5.23% with an undetectable IC50. Azithromycin caused bradyarrhythmia primarily by inhibiting L-type Ca2+ and Na+ currents.