Factors influencing the job embeddedness of new graduate nurses: A multicentre cross-sectional study.

AIM: To identify factors associated with job embeddedness from the perspective of retaining new graduate nurses. DESIGN: The study was cross-sectional in design. METHODS: Convenience and stratified sampling were used to recruit 415 newly graduated nurses from 12 tertiary hospitals in China. Anonymized data were collected through self-designed sociodemographic questionnaires, job embeddedness scale, feedback-seeking behaviour scale, authentic leadership perception scale and decent work scale. Appropriate indicators were used for descriptive statistics and t-tests, ANOVA, Pearson correlation analysis and multiple linear regression to examine the influencing factors. RESULTS: The study showed that monthly income level, decent labour, authentic leadership and feedback-seeking behaviour were significant predictors of job embeddedness among new graduate nurses. CONCLUSION: The job embeddedness of new graduate nurses is moderate. Nursing managers need to construct reasonable and fair compensation incentives, adopt positive leadership styles and encourage proactive feedback-seeking behaviours to improve the job embeddedness of new graduate nurses and alleviate the nursing talent shortage. IMPACT: Exploring the factors influencing the job embeddedness of new graduate nurses provides a reference for establishing new graduate nurse retention strategies to help promote the career development of new graduate nurses and alleviate the nursing brain drain. REPORTING METHOD: We adhered to the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines. PATIENT OR PUBLIC CONTRIBUTION: No patient or public contribution.

"Discovering shine through feedback seeking"---feedback seeking among new graduate nurses: a qualitative study.

BACKGROUND: Feedback is critical to improving practitioners' clinical practice and professional growth. Although they are still considered junior practitioners, their feedback-seeking experiences have yet to be investigated. This study aimed to understand the fundamental thoughts and experiences of new graduate nurses regarding feedback-seeking and to identify the main factors that influence their feedback-seeking behaviors. METHODS: Conducting a descriptive phenomenological study, semi-structured in-depth interviews with newly graduated nurses from four hospitals in Zhejiang Province, China, face-to-face or via video call in the hospital conference room through purposive and snowball sampling. Interview data were evaluated using Colaizzi's 7-step phenomenological data analysis. The COREQ checklist was followed. RESULTS: A total of 15 new graduate nurses were interviewed as a sample, and 13 categories emerged from our data. They were categorized into four central elements: (1) perceptions and attitudes, (2) drivers, (3) dilemmas and needs, and (4) transformation and growth. CONCLUSIONS: This study found that new graduate nurses have various needs but face dilemmas in the feedback-seeking process. Nursing managers should be proficient at providing positive leadership, collaborating with clinical mentors to foster an atmosphere where new graduate nurses may obtain honest, transparent, and fair feedback, and exercising caution when providing negative feedback.

Commonwealth of Soil Health: How Do Earthworms Modify the Soil Microbial Responses to CeO2 Nanoparticles?

Soil ecotoxicological assays on nanoparticles (NPs) have mainly investigated single components (e.g., plants, fauna, and microbes) within the ecosystem, neglecting possible effects resulting from the disturbance of the interactions between these components. Here, we investigated soil microbial responses to CeO2 NPs in the presence and absence of earthworms from the perspectives of microbial functions (i.e., enzyme activities), the community structure, and soil metabolite profiles. Exposure to CeO2 NPs (50, 500 mg/kg) alone decreased the activities of enzymes (i.e., acid protease and acid phosphatase) participating in soil N and P cycles, while the presence of earthworms ameliorated these inhibitory effects. After the CeO2 NP exposure, the earthworms significantly altered the relative abundance of some microbes associated with the soil N and P cycles (Flavobacterium, Pedobacter, Streptomyces, Bacillus, Bacteroidota, Actinobacteria, and Firmicutes). This was consistent with the pattern found in the significantly changed metabolites which were also involved in the microbial N and P metabolism. Both CeO2 NPs and earthworms changed the soil bacterial community and soil metabolite profiles. Larger alterations of soil bacteria and metabolites were found under CeO2 NP exposure with earthworms. Overall, our study indicates that the top-down control of earthworms can drastically modify the microbial responses to CeO2 NPs from all studied biological aspects. This clearly shows the importance of the holistic consideration of all soil ecological components to assess the environmental risks of NPs to soil health.

Metal resistant gut microbiota facilitates snails feeding on metal hyperaccumulator plant Sedum alfredii in the phytoremediation field.

The interactions between hyperaccumulators and their associated herbivores have been mostly investigated in their natural habitats and largely ignored in the phytoremediation practice. Herein, we investigated the herbivory status of Zn/Cd-hyperaccumulating plant Sedum alfredii from both their natural habitats and their applied remediation field, and inspected the adaptive strategies of the herbivores from the perspective of their facilitative gut microbiota. Field investigations showed that snail species Bradybaena ravida was the dominant herbivore feeding on S. alfredii and they can be only found in sites with lower levels of heavy metals compared with the plant natural habitat. Gut microbial community was analyzed using two sequencing methods (16S rRNA and czcA-Zn/Cd resistant gene) to comparatively understand the effect of gut microbes in facilitating snail feeding on the hyperaccumulators. The results revealed significant differences in the diversity and richness between the gut microbiota of the two snail populations, which was more pronounced by the czcA sequencing method. Despite of the compositional differences, their functions seemed to converge into three categories as metal-tolerant and contaminant degraders, gut symbionts, and pathogens. Further function potentials predicted by Tax4Fun based on 16 S sequencing data were in accordance with this categorization as the most abundant metabolic pathways were two-component system and ABC transporter, which was closely related to metal stress adaptation. The prevalence of positive interactions (~80%) indicated by the co-occurrence network analysis based on czcA sequencing data in both groups of gut microbiota further suggested the facilitative effect of these metal-tolerant gut microbes in coping with the high metal diet, which ultimately assist the snails to successfully feed on S. alfredii plants and thrive. This work for the first time provides evidence that the herbivore adaptation to hyperaccumulators were also associated with their gut microbial adaptation to metals.

Inhibition of Ca2+-dependent protein kinase C rescues high calcium-induced pro-arrhythmogenic cardiac alternans in rabbit hearts.

Cardiac alternans closely linked to calcium dysregulation is a crucial risk factor for fatal arrhythmia causing especially sudden death. Calcium overload is well-known to activate Ca2+-dependent protein kinase C (PKC); however, the effects of PKC on arrhythmogenic cardiac alternans have not yet been investigated. This study aimed to determine the contributions of PKC activities in cardiac alternans associated with calcium cycling disturbances. In the present study, action potential duration alternans (APD-ALT) induced by high free intracellular calcium ([Ca2+]i) exerted not only in a calcium concentration-dependent manner but also in a frequency-dependent manner. High [Ca2+]i-induced APD-ALT was suppressed by not only BAPTA-AM but also nifedipine. On the other hand, PKC inhibitors BIM and Gö 6976 eliminated high [Ca2+]i-induced APD-ALT, and PKC activator PMA was found to induce APD-ALT at normal [Ca2+]i condition. Furthermore, BIM effectively prevented calcium transient alternans (CaT-ALT) and even CaT disorders caused by calcium overload. Moreover, BIM not only eliminated electrocardiographic T-wave alternans (TWA) caused by calcium dysregulation, but also lowered the incidence of ventricular arrhythmias in isolated hearts. What's more, BIM prevented the expression of PKC α upregulated by calcium overload in high calcium-perfused hearts. We firstly found that pharmacologically inhibiting Ca2+-dependent PKC over-activation suppressed high [Ca2+]i-induced cardiac alternans. This recognition indicates that inhibition of PKC activities may become a therapeutic target for the prevention of pro-arrhythmogenic cardiac alternans associated with calcium dysregulation.

Smoking Is Independently Associated With an Increased Risk for COVID-19 Mortality: A Systematic Review and Meta-analysis Based on Adjusted Effect Estimates.

INTRODUCTION: Smoking can cause mucociliary clearing dysfunction and poor pulmonary immunity, leading to more severe infection. We performed this study to explore the association between smoking and mortality of coronavirus disease 2019 (COVID-19) patients utilizing a quantitative meta-analysis on the basis of adjusted effect estimates. AIMS AND METHODS: We conducted a systematic search of the online databases including PubMed, Web of Science, Scopus, and Embase. Only articles reporting adjusted effect estimates on the association between smoking and the risk of mortality among COVID-19 patients in English were included. Newcastle-Ottawa scale was fitted to assess the risk of bias. A random-effects model was applied to calculate the pooled effect with the corresponding 95% confidence interval (CI). RESULTS: A total of 73 articles with 863 313 COVID-19 patients were included in this meta-analysis. Our results indicated that smoking was significantly associated with an increased risk for death in patients with COVID-19 (pooled relative risk = 1.19, 95% CI = 1.12-1.27). Sensitivity analysis indicated that our results were stable and robust. CONCLUSIONS: Smoking was independently associated with an increased risk for mortality in COVID-19 patients. IMPLICATIONS: This present study may contribute to summarizing the association between smoking and the risk of COVID-19 mortality based on adjusted effect estimates. More detailed and complete data on smoking status should be collected to more accurately estimate the effect of smoking on COVID-19 mortality.

Eleutheroside B, a selective late sodium current inhibitor, suppresses atrial fibrillation induced by sea anemone toxin II in rabbit hearts.

Eleutheroside B (EB) is the main active constituent derived from the Chinese herb Acanthopanax senticosus (AS) that has been reported to possess cardioprotective effects. In this study we investigated the effects of EB on cardiac electrophysiology and its suppression on atrial fibrillation (AF). Whole-cell recording was conducted in isolated rabbit atrial myocytes. The intracellular calcium ([Ca2+]i) concentration was measured using calcium indicator Fura-2/AM fluorescence. Monophasic action potential (MAP) and electrocardiogram (ECG) synchronous recordings were conducted in Langendorff-perfused rabbit hearts using ECG signal sampling and analysis system. We showed that EB dose-dependently inhibited late sodium current (INaL), transient sodium current (INaT), and sea anemone toxin II (ATX II)-increased INaL with IC50 values of 167, 1582, and 181 µM, respectively. On the other hand, EB (800 µM) did not affect L-type calcium current (ICaL), inward rectifier potassium channel current (IK), and action potential duration (APD). Furthermore, EB (300 µM) markedly decreased ATX II-prolonged the APD at 90% repolarization (APD90) and eliminated ATX II-induced early afterdepolarizations (EADs), delayed afterdepolarizations (DADs), and triggered activities (TAs). Moreover, EB (200 µM) significantly suppressed ATX II-induced Na+-dependent [Ca2+]i overload in atrial myocytes. In the Langendorff-perfused rabbit hearts, application of EB (200 µM) or TTX (2 µM) substantially decreased ATX II-induced incidences of atrial fibrillation (AF), ventricular fibrillation (VF), and heart death. These results suggest that augmented INaL alone is sufficient to induce AF, and EB exerts anti-AF actions mainly via blocking INaL, which put forward the basis of pharmacology for new clinical application of EB.

A meta-analysis on the risk factors adjusted association between cardiovascular disease and COVID-19 severity.

BACKGROUND: Cardiovascular disease (CVD), one of the most common comorbidities of coronavirus disease 2019 (COVID-19), has been suspected to be associated with adverse outcomes in COVID-19 patients, but their correlation remains controversial. METHOD: This is a quantitative meta-analysis on the basis of adjusted effect estimates. PubMed, Web of Science, MedRxiv, Scopus, Elsevier ScienceDirect, Cochrane Library and EMBASE were searched comprehensively to obtain a complete data source up to January 7, 2021. Pooled effects (hazard ratio (HR), odds ratio (OR)) and the 95% confidence intervals (CIs) were estimated to evaluate the risk of the adverse outcomes in COVID-19 patients with CVD. Heterogeneity was assessed by Cochran's Q-statistic, I2test, and meta-regression. In addition, we also provided the prediction interval, which was helpful for assessing whether the variation across studies was clinically significant. The robustness of the results was evaluated by sensitivity analysis. Publication bias was assessed by Begg's test, Egger's test, and trim-and-fill method. RESULT: Our results revealed that COVID-19 patients with pre-existing CVD tended more to adverse outcomes on the basis of 203 eligible studies with 24,032,712 cases (pooled ORs = 1.41, 95% CIs: 1.32-1.51, prediction interval: 0.84-2.39; pooled HRs = 1.34, 95% CIs: 1.23-1.46, prediction interval: 0.82-2.21). Further subgroup analyses stratified by age, the proportion of males, study design, disease types, sample size, region and disease outcomes also showed that pre-existing CVD was significantly associated with adverse outcomes among COVID-19 patients. CONCLUSION: Our findings demonstrated that pre-existing CVD was an independent risk factor associated with adverse outcomes among COVID-19 patients.

Elevated interleukin-6 and adverse outcomes in COVID-19 patients: a meta-analysis based on adjusted effect estimates.

This study aimed to evaluate the association of interleukin-6 (IL-6) level with the poor outcomes in coronavirus disease 2019 (COVID-19) patients by utilizing a meta-analysis based on adjusted effect estimates. We searched the keywords from PubMed, Web of Science, and EMBASE on August 14, 2020. The pooled effects and 95% confidence interval (95% CI) were estimated by Stata 11.2. Subgroup analysis and meta-regression were performed to explore the source of heterogeneity. Sensitivity analysis was implemented to assess the stability of the results. Begg's test and Egger's test were conducted to assess the publication bias. Sixteen articles with 8752 COVID-19 patients were finally included in the meta-analysis. The results based on random-effects model indicated that elevated value of IL-6 was significantly associated with adverse outcomes in patients with COVID-19 (pooled effect = 1.21, 95% CI 1.13-1.31, I2 = 90.7%). Subgroup analysis stratified by disease outcomes showed consistent results (severe: pooled effect = 1.18, 95% CI 1.05-1.31; ICU (intensive care unit) admission: pooled effect = 1.90, 95% CI 1.04-3.47; death: pooled effect = 3.57, 95% CI 2.10-6.07). Meta-regression indicated that study design was a source of heterogeneity. Publication bias was existent in our analysis (Begg's test: P = 0.007; Egger's test: P < 0.001). In conclusion, the elevated IL-6 level is an independent risk factor associated with adverse outcomes in patients with COVID-19.

Identification of key biomarkers associated with cell adhesion in multiple myeloma by integrated bioinformatics analysis.

BACKGROUND: Multiple Myeloma (MM) is a hematologic malignant disease whose underlying molecular mechanism has not yet fully understood. Generally, cell adhesion plays an important role in MM progression. In our work, we intended to identify key genes involved in cell adhesion in MM. METHODS: First, we identified differentially expressed genes (DEGs) from the mRNA expression profiles of GSE6477 dataset using GEO2R with cut-off criterion of p < 0.05 and [logFC] ≥ 1. Then, GO and KEGG analysis were performed to explore the main function of DEGs. Moreover, we screened hub genes from the protein-protein interaction (PPI) network analysis and evaluated their prognostic and diagnostic values by the PrognoScan database and ROC curves. Additionally, a comprehensive analysis including clinical correlation analysis, GSEA and transcription factor (TF) prediction, pan-cancer analysis of candidate genes was performed using both clinical data and mRNA expression data. RESULTS: First of all, 1383 DEGs were identified. Functional and pathway enrichment analysis suggested that many DEGs were enriched in cell adhesion. 180 overlapped genes were screened out between the DEGs and genes in GO terms of cell adhesion. Furthermore, 12 genes were identified as hub genes based on a PPI network analysis. ROC curve analysis demonstrated that ITGAM, ITGB2, ITGA5, ITGB5, CDH1, IL4, ITGA9, and LAMB1 were valuable biomarkers for the diagnosis of MM. Further study demonstrated that ITGA9 and LAMB1 revealed prognostic values and clinical correlation in MM patients. GSEA and transcription factor (TF) prediction suggested that MYC may bind to ITGA9 and repress its expression and HIF-1 may bind to LAMB1 to promote its expression in MM. Additionally, pan-cancer analysis showed abnormal expression and clinical outcome associations of LAMB1 and ITGA9 in multiple cancers. CONCLUSION: In conclusion, ITGA9 and LAMB1 were identified as potent biomarkers associated with cell adhesion in MM.

miR-582-5p serves as an antioncogenic biomarker in intermediate risk AML with normal cytogenetics and could inhibit proliferation and induce apoptosis of leukemia cells.

Numerous studies confirmed that aberrant microRNA (miRNA) expression contributes to cancer development and progression. We carried out this study to explore the expression profile of miRNAs in intermediate risk acute myeloid leukemia (AML) and locate certain miRNAs as biomarkers. We profiled differentially expressed miRNAs by performing miRNA sequencing analysis in the patients' samples. Bioinformatic analysis showed the most significantly expressed genes mostly involved in cellular component organization, cell differentiation, and cell development. Reverse-transcription polymerase chain reaction validated the expression of miR-582-5p in different groups of AML samples. It was confirmed that miR-582-5p was downregulated in newly diagnosed AML and relapse/refractory AML compared with CR AML or controls. Among intermediate risk AML patients with normal cytogenetics, a lower level of miR-582-5p is correlated with an unfavorable outcome, and a shorter overall survival. Gain- and loss-of-function experiments revealed that miR-582-5p could inhibit proliferation, suppress migration, and invasion ability and induce apoptosis of leukemia cells. Furthermore, overexpression of miR-582-5p can increase sensitivity of cells to Ara-C. In conclusion, miR-582-5p can serve as an antioncogenic biomarker in intermediate risk AML with normal cytogenetics for risk classification and outcome prediction. These results showed a novel role for miR-582-5p in predicting the prognosis and promoting the tumor growth of AML.

Late Sodium Current in Atrial Cardiomyocytes Contributes to the Induced and Spontaneous Atrial Fibrillation in Rabbit Hearts.

Increased late sodium current (INa) induces long QT syndrome 3 with increased risk of atrial fibrillation (AF). The role of atrial late INa in the induction of AF and in the treatment of AF was determined in this study. AF parameters were measured in isolated rabbit hearts exposed to late INa enhancer and inhibitors. Late INa from isolated atrial and ventricular myocytes were measured using whole-cell patch-clamp techniques. We found that induced-AF by programmed S1S2 stimulation and spontaneous episodes of AF were recorded in hearts exposed to either low (0.1-3 nM) or high (3-10 nM) concentrations of ATX-II (n = 10). Prolongations in atrial monophasic action potential duration at 90% completion of repolarization and effective refractory period by ATX-II (0.1-15 nM) were greater in hearts paced at slow than at fast rates (n = 5-10, P < 0.05). Both endogenous and ATX-II-enhanced late INa density were greater in atrial than that in ventricular myocytes (n = 9 and 8, P < 0.05). Eleclazine and ranolazine reduced AF window and AF burden in association with the inhibition of both endogenous and enhanced atrial late INa with half maximal inhibitory concentrations (IC50) of 1.14 and 9.78, and 0.94 and 8.31 µM, respectively. The IC50s for eleclazine and ranolazine to inhibit peak INa were 20.67 and 101.79 µM, respectively, in atrial myocytes. In conclusion, enhanced late INa in atrial myocytes increases the susceptibility for AF. Inhibition of either endogenous or enhanced late INa, with increased atrial potency of drugs is feasible for the treatment of AF.

High Expression Levels of Long Noncoding RNA Small Nucleolar RNA Host Gene 18 and Semaphorin 5A Indicate Poor Prognosis in Multiple Myeloma.

BACKGROUND: The aim of this study was to detect the expression of long noncoding RNA small nucleolar RNA host gene 18 (SNHG18) andsemaphorin 5A (SEMA5A) genes in multiple myeloma (MM) patients and to explore the correlation of the expression of these genes with the clinical characteristics and prognosis of MM patients. METHODS: Forty-seven newly diagnosed MM, 18 complete remission MM, 13 refractory/relapse MM, and 22 iron deficiency anemia (serving as control) samples were extracted at the Department of Hematology, Second Affiliated Hospital of Xian Jiaotong University between January 2015 and December 2016. The clinical features of the MM patients are summarized. Real-time quantitative PCR was performed to analyze the relative expression levels of the SNHG18 and SEMA5Agenes. The clinical characteristics and overall survival (OS) of the MM patients were statistically analyzed while measuring different levels of SNHG18 and SEMA5Agene expression. At the same time, the correlation between the expression of SNHG18 and SEMA5A was also analyzed. RESULTS: The analysis confirmed that SNHG18 and its possible target gene SEMA5A were both highly expressed in newly diagnosed MM patients. After analyzing the clinical significance of SNHG18 and SEMA5A in MM patients, we found that the expression of SNHG18 and SEMA5A was related to the Durie-Salmon (DS), International Staging System (ISS), and Revised International Staging System (R-ISS) classification systems, and the Mayo Clinic Risk Stratification for Multiple Myeloma (mSMART; p < 0.05). Moreover, we observed a significant difference in OS between the SNHG18/SEMA5A high expression group and the low expression group. We found a positive correlation between SNHG18 and SEMA5A expression (r = 0.709, p < 0.01). Surprisingly, the expected median OS times of both the SNHG18 and SEMA5Ahigh expression groups were significantly decreased, which was in contrast to those of both the SNHG18 and SEMA5Alow expression groups and the single-gene high expression group (p < 0.05). CONCLUSION: High expression of both SNHG18 and SEMA5A is associated with poor prognosis in patients with MM.

The Association of Cerebrovascular Disease with Adverse Outcomes in COVID-19 Patients: A Meta-Analysis Based on Adjusted Effect Estimates.

OBJECTIVE: The aim of this study was to address the association between cerebrovascular disease and adverse outcomes in coronavirus disease 2019 (COVID-19) patients by using a quantitative meta-analysis based on adjusted effect estimates. METHOD: A systematic search was performed in PubMed, Web of Science, and EMBASE up to August 10th, 2020. The adjusted effect estimates were extracted and pooled to evaluate the risk of the unfavorable outcomes in COVID-19 patients with cerebrovascular disease. Subgroup analysis and meta-regression were also carried out. RESULTS: There were 12 studies with 10,304 patients included in our meta-analysis. A significant trend was observed when evaluating the association between cerebrovascular disease and adverse outcomes (pooled effect = 2.05, 95% confidence interval (CI): 1.34-3.16). In addition, the pooled effects showed that patients with a history of cerebrovascular disease had more likelihood to progress fatal outcomes than patients without a history of cerebrovascular disease (pooled effect = 1.78, 95% CI: 1.04-3.07). CONCLUSION: This study for the first time indicated that cerebrovascular disease was an independent risk factor for predicting the adverse outcomes, particularly fatal outcomes, in COVID-19 patients on the basis of adjusted effect estimates. Well-designed studies with larger sample size are needed for further verification.

Barbaloin inhibits ventricular arrhythmias in rabbits by modulating voltage-gated ion channels.

Barbaloin (10-ß-D-glucopyranosyl-1,8-dihydroxy-3-(hydroxymethyl)-9(10H)-anthracenone) is extracted from the aloe plant and has been reported to have anti-inflammatory, antitumor, antibacterial, and other biological activities. Here, we investigated the effects of barbaloin on cardiac electrophysiology, which has not been reported thus far. Cardiac action potentials (APs) and ionic currents were recorded in isolated rabbit ventricular myocytes using whole-cell patch-clamp technique. Additionally, the antiarrhythmic effect of barbaloin was examined in Langendorff-perfused rabbit hearts. In current-clamp recording, application of barbaloin (100 and 200 µmol/L) dose-dependently reduced the action potential duration (APD) and the maximum depolarization velocity (Vmax), and attenuated APD reverse-rate dependence (RRD) in ventricular myocytes. Furthermore, barbaloin (100 and 200 µmol/L) effectively eliminated ATX II-induced early afterdepolarizations (EADs) and Ca2+-induced delayed afterdepolarizations (DADs) in ventricular myocytes. In voltage-clamp recording, barbaloin (10-200 µmol/L) dose-dependently inhibited L-type calcium current (ICa.L) and peak sodium current (INa.P) with IC50 values of 137.06 and 559.80 µmol/L, respectively. Application of barbaloin (100, 200 µmol/L) decreased ATX II-enhanced late sodium current (INa.L) by 36.6%±3.3% and 71.8%±6.5%, respectively. However, barbaloin up to 800 µmol/L did not affect the inward rectifier potassium current (IK1) or the rapidly activated delayed rectifier potassium current (IKr) in ventricular myocytes. In Langendorff-perfused rabbit hearts, barbaloin (200 µmol/L) significantly inhibited aconitine-induced ventricular arrhythmias. These results demonstrate that barbaloin has potential as an antiarrhythmic drug.

Sodium Houttuyfonate Inhibits Voltage-Gated Peak Sodium Current and Anemonia Sulcata Toxin II-Increased Late Sodium Current in Rabbit Ventricular Myocytes.

AIM: Sodium houttuyfonate (SH), a chemical compound originating from Houttuynia cordata, has been reported to have anti-inflammatory, antibacterial, and antifungal effects, as well as cardioprotective effects. In this study, we investigated the effects of SH on cardiac electrophysiology, because to the best of our knowledge, this issue has not been previously investigated. METHODS: We used the whole-cell patch-clamp technique to explore the effects of SH on peak sodium current (INa.P) and late sodium current (INa.L) in isolated rabbit ventricular myocytes. To test the drug safety of SH, we also investigated the effect of SH on rapidly activated delayed rectifier potassium current (IKr). RESULTS: SH (1, 10, 50, and 100 µmol/L) inhibited INa.P in a concentration-dependent manner with an IC50 of 78.89 µmol/L. In addition, SH (100 µmol/L) accelerated the steady state inactivation of INa.P. Moreover, 50 and 100 µmol/L SH inhibited Anemonia sulcata toxin II (ATX II)-increased INa.L by 30.1 and 57.1%, respectively. However, SH (50 and 100 µmol/L) only slightly affected IKr. CONCLUSIONS: The inhibitory effects of SH on ATX II-increased INa.L may underlie the electrophysiological mechanisms of the cardioprotective effects of SH; SH has the potential to be an effective and safe antiarrhythmic drug.

Modulation of late sodium current by Ca2+ -calmodulin-dependent protein kinase II, protein kinase C and Ca2+ during hypoxia in rabbit ventricular myocytes.

NEW FINDINGS: What is the central question of this study? Hypoxia-induced increase in late sodium current (INa,L ) is associated with conditions causing cellular Ca2+ overload and contributes to arrhythmogenesis in the ventricular myocardium. The INa,L is an important drug target. We investigated intracellular signal transduction pathways involved in modulation of INa,L during hypoxia. What is the main finding and its importance? Hypoxia caused increases in INa,L , reverse Na+ -Ca2+ exchange current and diastolic [Ca2+ ], which were attenuated by inhibitors of Ca2+ -calmodulin-dependent protein kinase II (CaMKII) and protein kinase C and by a Ca2+ chelator. The findings suggest that CaMKII, protein kinase C and Ca2+ all participate in mediation of the effect of hypoxia to increase INa,L . Hypoxia leads to augmentation of the late sodium current (INa,L ) and cellular Na+ loading, increased reverse Na+ -Ca2+ exchange current (reverse INCX ) and intracellular Ca2+ loading in rabbit ventricular myocytes. The purpose of this study was to determine the intracellular signal transduction pathways involved in the modulation of INa,L during hypoxia in ventricular myocytes. Whole-cell and cell-attached patch-clamp techniques were used to record INa,L , and the whole-cell mode was also used to record reverse INCX and to study intercellular signal transduction mechanisms that mediate the increased INa,L . Dual excitation fluorescence photomultiplier systems were used to record the calcium transient in ventricular myocytes. Hypoxia caused increases of INa,L and reverse INCX . These increases were attenuated by KN-93 (an inhibitor of Ca2+ -calmodulin-dependent protein kinase II), bisindolylmaleimide VI (BIM; an inhibitor of protein kinase C) and BAPTA AM (a Ca2+ chelator). KN-93, BIM and BAPTA AM had no effect on INa,L in normoxia. In studies of KN-93, hypoxia alone increased the density of INa,L from -0.31 ± 0.02 to -0.66 ± 0.03 pA pF-1 (n = 6, P < 0.01 versus control) and the density of reverse INCX from 1.02 ± 0.06 to 1.91 ± 0.20 pA pF-1 (n = 7, P < 0.01 versus control) in rabbit ventricular myocytes. In the presence of 1 µm KN-93, the densities of INa,L and reverse INCX during hypoxia were significantly attenuated to -0.44 ± 0.03 (n = 6, P < 0.01 versus hypoxia) and 1.36 ± 0.15 pA pF-1 (n = 7, P < 0.01 versus hypoxia), respectively. In studies of BIM, hypoxia increased INa,L from -0.30 ± 0.03 to -0.60 ± 0.03 pA pF-1 (n = 6, P < 0.01 versus control) and reverse INCX from 0.91 ± 0.10 to 1.71 ± 0.27 pA pF-1 (n = 6, P < 0.01 versus control). In the presence of 1 µm BIM, the densities of INa,L and reverse INCX during hypoxia were significantly attenuated to -0.48 ± 0.02 (n = 6, P < 0.01 versus hypoxia) and 1.33 ± 0.21 pA pF-1 (n = 6, P < 0.01 versus hypoxia), respectively. In studies of BAPTA AM, hypoxia increased INa,L from -0.26 ± 0.04 to -0.63 ± 0.05 pA pF-1 (n = 6, P < 0.01 versus control) and reverse INCX from 0.86 ± 0.09 to 1.68 ± 0.35 pA pF-1 (n = 6, P < 0.01 versus control). The effects of hypoxia on INa,L and reverse INCX were significantly attenuated in the presence of 1 mm BAPTA AM to -0.39 ± 0.02 (n = 6, P < 0.01 versus hypoxia) and 1.12 ± 0.27 pA pF-1 (n = 6, P < 0.01 versus hypoxia), respectively. Results of single-channel studies showed that hypoxia apparently increased the mean open probability and mean open time of sodium channels. These effects were inhibited by either 1 µm KN-93 or 1 mm BAPTA AM. The suppressant effects of drug interventions were reversed upon washout. In addition, KN-93, BIM and BAPTA AM also reversed the hypoxia-enhanced diastolic Ca2+ concentration and the attenuated amplitude of the [Ca2+ ]i transient, maximal velocities of Ca2+ increase and Ca2+ decay. In summary, the findings suggest that Ca2+ -calmodulin-dependent protein kinase II, protein kinase C and Ca2+ all participate in mediation of the effect of hypoxia to increase INa,L .

Wenxin Keli diminishes Ca2+ overload induced by hypoxia/reoxygenation in cardiomyocytes through inhibiting INaL and ICaL.

BACKGROUND: An increase in the late sodium current (INaL ) causes intracellular Na+ overload and subsequently intracellular Ca2+ ([Ca2+ ]i ) overload via the stimulated reverse Na+ -Ca2+ exchange (NCX). Wenxin Keli (WXKL) is an effective antiarrhythmic Chinese herb extract, but the underlying mechanisms are unclear. METHODS AND RESULTS: The INaL , NCX current (INCX ), L-type Ca2+ current (ICaL ), and action potentials were recorded using the whole-cell patch-clamp technique in rabbit ventricular myocytes. Myocyte [Ca2+ ]i transients were measured using a dual excitation fluorescence photomultiplier system. WXKL decreased the enhanced INaL , reverse INCX , diastolic [Ca2+ ]i , and the amplitude of Ca2+ transients induced by sea anemone toxin II (ATX II, a specific INaL channel opener) in a concentration-dependent manner. Hypoxia increased INaL , INCX , and diastolic [Ca2+ ]i , and decreased amplitude of [Ca2+ ]i transients. Hypoxia-reoxygenation aggravated these changes and induced spontaneous [Ca2+ ]i transients and hypercontraction in 86% cells (6/7). The application of WXKL during hypoxia or reoxygenation periods decreased the increased INaL , INCX , and diastolic [Ca2+ ]i , and prevented those events in 82% cells (9/11) under hypoxia-reoxygenation conditions. WXKL also inhibited the ICaL in a dose-dependent manner. Furthermore, WXKL shortened the action potential duration and completely abolished ATX II-induced early afterdepolarizations from 9/9 to /9. In isolated heart electrocardiogram recordings, WXKL inhibited ischemia-reperfusion induced ventricular premature beats and tachycardia. CONCLUSIONS: WXKL attenuated [Ca2+ ]i overload induced by hypoxia-reoxygenation in ventricular myocytes through inhibiting INaL and ICaL and prevents arrhythmias. This could, at least partly, contribute to the antiarrhythmic effects of WXKL.

The Inhibitory Effects of Ketamine on Human Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels and Action Potential in Rabbit Sinoatrial Node.

AIMS: To investigate the effects of ketamine on human hyperpolarization-activated cyclic nucleotide-gated (hHCN) 1, 2, 4 channel currents expressed in Xenopus oocytes and spontaneous action potentials (APs) of rabbit sinoatrial node (SAN). METHODS: The 2-electrode voltage clamp and standard microelectrode techniques were respectively applied to record hHCN channels currents expressed in Xenopus oocytes and APs of SAN separated from rabbit heart. RESULTS: Ketamine (1-625 µmol/L) blocked hHCN1, 2, and 4 currents with IC50 of 67.0, 89.1, and 84.0 µmol/L, respectively, in a concentration-dependent manner. The currents were rapidly blocked by ketamine and partially recovered after washout. The steady-state activation curves of hHCN1, 2, and 4 currents demonstrated a concentration-dependent shift to the left and the rates of activation were significantly decelerated. But ketamine blocked hHCN channels in a voltage-independence and non-use-dependent manner, and did not modify the voltage dependence of activation and reversal potentials. Furthermore, ketamine suppressed phase-4 spontaneous depolarization rate in isolated rabbit SAN and decreased the beat rates in a concentration-dependent manner. CONCLUSION: Ketamine could inhibit hHCN channels expressed in Xenopus oocytes in a concentration-dependent manner as a close-state blocker and decrease beat rates of isolated rabbit SAN. This study may provide novel insights into other unexplained actions of ketamine.

The effects of microvesicles on endothelial progenitor cells are compromised in type 2 diabetic patients via downregulation of the miR-126/VEGFR2 pathway.

Our previous study showed that circulating microvesicles (cMVs) of diabetic mice have negative effects on the function of endothelial progenitor cells (EPCs). Whether this is true in diabetic patients deserves further study. In this study, the effects of cMVs and EPC-derived MVs (EPC-MVs) on EPC migration, apoptosis, and reactive oxygen species (ROS) production in healthy controls, well-controlled, and uncontrolled diabetic patients were investigated. The levels of miR-126 and vascular endothelial growth factor receptor 2 (VEGFR2) in cMVs, EPC-MVs, and/or EPCs were analyzed. Moreover, miR-126 inhibitor or mimic was applied to EPCs to modulate the miR-126 level in EPC-MVs. We found the following: 1) the circulating EPC level was reduced but the circulating EPC-MV level increased in uncontrolled diabetic patients; 2) the cMVs and EPC-MVs of healthy controls had beneficial effects on EPCs (migration, apoptosis, ROS), whereas the effects were reversely changed in the cMVs and EPC-MVs of uncontrolled diabetic patients; and 3) the cMVs and EPC-MVs of uncontrolled diabetic patients carried less miR-126 and had downregulated VEGFR2 expression in EPCs. Manipulating the miR-126 level in EPC-MVs with inhibitor or mimic changed their function. The effects of cMVs and EPC-MVs are compromised in diabetes due to the reduction of their carried miR-126, which might provide a therapy target for diabetic vascular complications.