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.

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.

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.

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.

Tolterodine reduces veratridine-augmented late INa, reverse-INCX and early afterdepolarizations in isolated rabbit ventricular myocytes.

AIM: The augmentation of late sodium current (INa.L) not only causes intracellular Na+ accumulation, which results in intracellular Ca2+ overload via the reverse mode of the Na+/Ca2+ exchange current (reverse-INCX), but also prolongs APD and induces early afterdepolarizations (EAD), which can lead to arrhythmia and cardiac dysfunction. Thus, the inhibition of INa.L is considered to be a potential way for therapeutic intervention in ischemia and heart failure. In this study we investigated the effects of tolterodine (Tol), a competitive muscarinic receptor antagonist, on normal and veratridine (Ver)-augmented INa.L, reverse-INCX and APD in isolated rabbit ventricular myocytes, which might contribute to its cardioprotective activity. METHODS: Rabbit ventricular myocytes were prepared. The INa.L and reverse-INCX were recorded in voltage clamp mode, whereas action potentials and Ver-induced early afterdepolarizations (EADs) were recorded in current clamp mode. Drugs were applied via superfusion. RESULTS: Tol (3-120 nmol/L) concentration-dependently inhibited the normal and Ver-augmented INa.L with IC50 values of 32.08 nmol/L and 42.47 nmol/L, respectively. Atropine (100 µmol/L) did not affect the inhibitory effects of Tol (30 nmol/L) on Ver-augmented INa.L. In contrast, much high concentrations of Tol was needed to inhibit the transient sodium current (INa.T) with an IC50 value of 183.03 µmol/L. In addition, Tol (30 nmol/L) significantly shifted the inactivation curve of INa.T toward a more depolarizing membrane potential without affecting its activation characteristics. Moreover, Tol (30 nmol/L) significantly decreased Ver-augmented reverse-INCX. Tol (30 nmol/L) increased the action potential duration (APD) by 16% under the basal conditions. Ver (20 µmol/L) considerably extended the APD and evoked EADs in 18/24 cells (75%). In the presence of Ver, Tol (30 nmol/L) markedly decreased the APD and eliminated EADs (0/24 cells). CONCLUSION: Tol inhibits normal and Ver-augmented INaL and decreases Ver-augmented reverse-INCX. In addition, Tol reverses the prolongation of the APD and eliminates the EADs induced by Ver, thus prevents Ver-induced arrhythmia.

Ketamine attenuates the Na+-dependent Ca2+ overload in rabbit ventricular myocytes in vitro by inhibiting late Na+ and L-type Ca2+ currents.

AIM: Intracellular Ca(2+) ([Ca(2+)]i) overload occurs in myocardial ischemia. An increase in the late sodium current (INaL) causes intracellular Na(+) overload and subsequently [Ca(2+)]i overload via the reverse-mode sodium-calcium exchanger (NCX). Thus, inhibition of INaL is a potential therapeutic target for cardiac diseases associated with [Ca(2+)]i overload. The aim of this study was to investigate the effects of ketamine on Na(+)-dependent Ca(2+) overload in ventricular myocytes in vitro. METHODS: Ventricular myocytes were enzymatically isolated from hearts of rabbits. INaL, NCX current (INCX) and L-type Ca(2+) current (ICaL) were recorded using whole-cell patch-clamp technique. Myocyte shortening and [Ca(2+)]i transients were measured simultaneously using a video-based edge detection and dual excitation fluorescence photomultiplier system. RESULTS: Ketamine (20, 40, 80 µmol/L) inhibited INaL in a concentration-dependent manner. In the presence of sea anemone toxin II (ATX, 30 nmol/L), INaL was augmented by more than 3-fold, while ketamine concentration-dependently suppressed the ATX-augmented INaL. Ketamine (40 µmol/L) also significantly suppressed hypoxia or H2O2-induced enhancement of INaL. Furthermore, ketamine concentration-dependently attenuated ATX-induced enhancement of reverse-mode INCX. In addition, ketamine (40 µmol/L) inhibited ICaL by 33.4%. In the presence of ATX (3 nmol/L), the rate and amplitude of cell shortening and relaxation, the diastolic [Ca(2+)]i, and the rate and amplitude of [Ca(2+)]i rise and decay were significantly increased, which were reverted to control levels by tetrodotoxin (TTX, 2 µmol/L) or by ketamine (40 µmol/L). CONCLUSION: Ketamine protects isolated rabbit ventricular myocytes against [Ca(2+)]i overload by inhibiting INaL and ICaL.

Ranolazine attenuates the enhanced reverse Na⁺-Ca²âº exchange current via inhibiting hypoxia-increased late sodium current in ventricular myocytes.

Ranolazine (RAN), a novel antianginal agent, inhibits the increased late sodium current (INa.L) under many pathological conditions. In this study, the whole-cell patch-clamp technique was used to explore the effects of RAN on INa.L and reverse Na(+)/Ca(2+) exchange current (INCX) in rabbit ventricular myocytes during hypoxia.Tetrodotoxin (TTX) at 2 µM or RAN at 9 µM decreased significantly INa.L and reverse INCX under normoxia and RAN had no further effects on both currents in the presence of TTX. RAN (3, 6, and 9 µM) attenuated hypoxia-increased INa.L and reverse INCX in a concentration-dependent manner. Hypoxia-increased INa.L and reverse INCX were inhibited by 2 µM TTX, whereas 9 µM RAN applied sequentially did not further decrease both currents. In another group, after both currents were decreased by 9 µM RAN, 2 µM TTX had no further effects in the presence of Ran. In monophasic action potential (MAP) recording, early after-depolarizations (EADs) were suppressed by RAN (9 µM) during hypoxia. In conclusion, RAN decreased reverse INCX by inhibiting INa.L in normoxia, concentration-dependently attenuated the increase of INa.L, which thereby decreased the reverse INCX, and obviously relieved EADs during hypoxia.

Effects of acute and chronic heat stress on the rumen microbiome in dairy goats.

Objective: The objective of this study was to reveal the influence of acute and chronic heat stress (HS) on the abundance and function of rumen microbiome and host metabolism. Methods: The forty mid-lactation goats were randomly divided into two artificial environments a control group and a heat-stressed group. This study was collected from two periods, 1 day and 28 days. The first day was defined as control 1 (CT1) and HS 1 (acute HS), and the last day was defined as CT28 and HS28 (chronic HS). On the first and last day, 6 dairy goats in each group were randomly selected to collect rumen liquid after the morning feeding through oral stomach tubes. The barn temperature and humidity were recorded every day. Results: Disruption of the rumen microbiome was observed under chronic HS, represented by an increase in the abundance of Prevotella and Bacteroidales (p<0.05), and upregulation of carbohydrate transport and metabolism functions (p<0.05). Additionally, the abundance of Succinimonas and Ruminobacter in chronic HS is lower than in acute HS (p<0.05), and the functions of intracellular trafficking, secretion and vesicular transport, and the cytoskeleton were downregulated (p<0.05). Conclusion: HS affected the interaction between the microbiota and host, thereby regulating milk production in dairy goats. These findings increased understanding of the crosstalk between hosts and microorganisms.

Procaine, a state-dependent blocker, inhibits HERG channels by helix residue Y652 and F656 in the S6 transmembrane domain.

The article evaluated the inhibitory action of procaine on wild-type and mutated HERG potassium channel current (I(HERG)) to determine whether mutations in the S6 region are important for the inhibition of I(HERG) by procaine. HERG channels (WT, Y652A, and F656A) were expressed in Xenopus laevis oocytes and studied using the standard two-microelectrode voltage-clamp technique. The results revealed that WT HERG is blocked in a concentration-, voltage-, and state-dependent manner by procaine ([IC50] = 34.79 µM). The steady state activation curves slightly move to the negative, while inactivation parameters move to the positive in the presence of procaine. Time-dependent test reveals that voltage-dependent I(HERG) blockade occurs extremely rapidly. Furthermore, the mutation to Ala of Y652 and F656 produce about 11-fold and 18-fold increases in IC50 for I(HERG) blockade, respectively. Simultaneously, for Y652A, the steady state activation and inactivation parameters are shifted to more positive values after perfusion of procaine. Conclusively, procaine state-dependently inhibits HERG channels (WT, Y652A, and F656A). The helix residues Y652 and F656 in the S6 transmembrane domain might play a role in interaction of the drug with the channel.

Sophocarpine attenuates the Na(+)-dependent Ca2(+) overload induced by Anemonia sulcata toxin-increased late sodium current in rabbit ventricular myocytes.

Many studies indicate that an increase in late sodium current (I(Na.L)) of cardiomyocytes causes intracellular Na overload and subsequently raises the reverse Na/Ca exchanger current (INCX), ultimately resulting in intracellular Ca overload. Therefore, using drugs to inhibit the increased INa.L under various pathological conditions can lower intracellular Ca overload. This study was intended to explore the effect of sophocarpine (SOP) on the increase in INa.L, INCX, calcium transient and contraction in rabbit ventricular myocytes induced by Anemonia sulcata toxin II (ATX II), an opener of sodium channel, with the application of whole-cell patch-clamp techniques, the video-based motion edge detection system, and the intracellular calcium concentration determination system. The results indicate that tetrodotoxin (TTX, 4 µM ) obviously decreased INa.L and INCX enlarged by ATX II (30 nM), and SOP (20, 40, and 80 µM) also inhibited both the parameters concentration dependently in rabbit ventricular myocytes. However, transient sodium current remained unaffected by the above-mentioned concentrations of ATX II, TTX, and SOP. In addition, SOP also reversed diastolic calcium concentration, calcium transient amplitude, and ventricular muscle contractility augmented by ATX II. Its effects were similar to those of TTX, a specific inhibitor of the sodium channel. In conclusion, SOP inhibits INa.L, INCX, diastolic Ca concentration, and contractility in rabbit ventricular myocytes, which suggests that relief of intracellular Ca overload through inhibiting INa.L is likely to become a new therapeutic mechanism of SOP against arrhythmia and myocyte damage associated with intracellular Ca overload.

[Involvement of veratridine-induced increase of reverse Na(+)/Ca(2+) exchange current in intracellular Ca(2+) overload and extension of action potential duration in rabbit ventricular myocytes].

The objectives of this study were to investigate the effects of veratridine (VER) on persistent sodium current (I(Na.P)), Na(+)/Ca(2+) exchange current (I(NCX)), calcium transients and the action potential (AP) in rabbit ventricular myocytes, and to explore the mechanism in intracellular calcium overload and myocardial contraction enhancement by using whole-cell patch clamp recording technique, visual motion edge detection system, intracellular calcium measurement system and multi-channel physiological signal acquisition and processing system. The results showed that I(Na.P) and reverse I(NCX) in ventricular myocytes were obviously increased after giving 10, 20 µmol/L VER, with the current density of I(Na.P) increasing from (-0.22 ± 0.12) to (-0.61 ± 0.13) and (-2.15 ± 0.14) pA/pF (P < 0.01, n = 10) at -20 mV, and that of reverse I(NCX) increasing from (1.62 ± 0.12) to (2.19 ± 0.09) and (2.58 ± 0.11) pA/pF (P < 0.05, n = 10) at +50 mV. After adding 4 µmol/L tetrodotoxin (TTX), current density of I(Na.P) and reverse I(NCX) returned to (-0.07 ± 0.14) and (1.69 ± 0.15) pA/pF (P < 0.05, n = 10). Another specific blocker of I(Na.P), ranolazine (RAN), could obviously inhibit VER-increased I(Na.P) and reverse I(NCX). After giving 2.5 µmol/L VER, the maximal contraction rate of ventricular myocytes increased from (-0.91 ± 0.29) to (-1.53 ± 0.29) µm/s (P < 0.01, n = 7), the amplitude of contraction increased from (0.10 ± 0.04) to (0.16 ± 0.04) µm (P < 0.05, n = 7), and the baseline of calcium transients (diastolic calcium concentration) increased from (1.21 ± 0.08) to (1.37 ± 0.12) (P < 0.05, n = 7). After adding 2 µmol/L TTX, the maximal contraction rate and amplitude of ventricular myocytes decreased to (-0.86 ± 0.24) µm/s and (0.09 ± 0.03) µm (P < 0.01, n = 7) respectively. And the baseline of calcium transients reduced to (1.17 ± 0.09) (P < 0.05, n = 7). VER (20 µmol/L) could extend action potential duration at 50% repolarization (APD(50)) and at 90% repolarization (APD(90)) in ventricular myocytes from (123.18 ± 23.70) to (271.90 ± 32.81) and from (146.94 ± 24.15) to (429.79 ± 32.04) ms (P < 0.01, n = 6) respectively. Early afterdepolarizations (EADs) appeared in 3 out of the 6 cases. After adding 4 µmol/L TTX, APD(50) and APD(90) were reduced to (99.07 ± 22.81) and (163.84 ± 26.06) ms (P < 0.01, n = 6) respectively, and EADs disappeared accordingly in 3 cases. It could be suggested that: (1) As a specific agonist of the I(Na.P), VER could result in I(Na.P) increase and intracellular Na(+) overload, and subsequently intracellular Ca(2+) overload with the increase of reverse I(NCX). (2) The VER-increased I(Na.P) could further extend the action potential duration (APD) and induce EADs. (3) TTX could restrain the abnormal VER-induced changes of the above-mentioned indexes, indicating that these abnormal changes were caused by the increase of I(Na.P). Based on this study, it is concluded that as the I(Na.P) agonist, VER can enhance reverse I(NCX) by increasing I(Na.P), leading to intracellular Ca(2+) overload and APD abnormal extension.

The complete chloroplast genome sequence of Ficus concinna (Moraceae) from Sichuan province.

Ficus concinna is an important contributor to tropical forest biodiversity. Here, we provide the first report of the complete F. concinna chloroplast genome, thereby providing a basis for subsequent phylogenetic analyses of the Moraceae family. The final assembled chloroplast genome was 160,331 bp in size and included a 20,018 bp long small single-copy (SSC) region, an 88,541 bp long large single-copy (LSC) region, and two 25,886 bp inverted repeats (IRs). The total content of GC for this chloroplast genome was 42.6%, with respective frequencies of 33.6%, 35.9%, and 28.9% in the SSC, LSC, and IR regions, accordingly. Overall, the chloroplast genome was found to encode 131 genes, comprising 37 tRNAs, 86 protein-coding genes, and 8 rRNAs. Phylogenetic analyses revealed a close relationship between F. concinna and Ficus altissima, consistent with prior research results. Together, these data provide valuable insights regarding the evolution and conserved genetic features of F. concinna.

Adenovirus-mediated human interleukin 24 (MDA-7/IL-24) selectively suppresses proliferation and induces apoptosis in keloid fibroblasts.

Keloids are fibroproliferative dermal lesions characterized by the proliferation of fibroblasts and the formation of excess scar tissue, for which no effective treatment exists. We transfected a replication-incompetent adenovirus vector expressing green fluorescent protein and interleukin-24 gene (Ad-GFP/IL-24) into keloid fibroblasts (KF) and normal dermal fibroblasts (NDF) in vitro to investigate the suppression effects by observation on cell lines growth, apoptosis, mitosis cycle, etc. The expression of GFP and IL-24 mRNA confirmed that Ad-GFP/IL-24 was transfected into KF and NDF successfully. The expression level of secreting IL-24 protein detected by enzyme-linked immunosorbent assay in Ad-GFP/IL-24-treated KF and PBS-treated NDF was higher than controls; treatment with Ad-GFP/IL-24 in KF induced growth suppression (71.83% ± 6.67%, P < 0.05 to 9.79% ± 3.34%, P < 0.01), apoptosis (24.2% ± 3.08% to 66.51% ± 5.29%, P < 0.01) and increased the percentage of the G2/M phase (42.26% ± 6.44%, P < 0.01) in KF but not in NDF. The data showed that the exogenous IL-24 gene could selectively inhibit human KF proliferation and induce significant apoptosis.

Blocking effect of methylflavonolamine on human Na(V)1.5 channels expressed in Xenopus laevis oocytes and on sodium currents in rabbit ventricular myocytes.

AIM: To investigate the blocking effects of methylflavonolamine (MFA) on human Na(V)1.5 channels expressed in Xenopus laevis oocytes and on sodium currents (I(Na)) in rabbit ventricular myocytes. METHODS: Human Na(V)1.5 channels were expressed in Xenopus oocytes and studied using the two-electrode voltage-clamp technique. I(Na) and action potentials in rabbit ventricular myocytes were studied using the whole-cell recording. RESULTS: MFA and lidocaine inhibited human Na(V)1.5 channels expressed in Xenopus oocytes in a positive rate-dependent and concentration-dependent manner, with IC(50) values of 72.61 micromol/L and 145.62 micromol/L, respectively. Both of them markedly shifted the steady-state activation curve of I(Na) toward more positive potentials, shifted the steady-state inactivation curve of I(Na) toward more negative potentials and postponed the recovery of the I(Na) inactivation state. In rabbit ventricular myocytes, MFA inhibited I(Na) with a shift in the steady-state inactivation curve toward more negative potentials, thereby postponing the recovery of the I(Na) inactivation state. This shift was in a positive rate-dependent manner. Under current-clamp mode, MAF significantly decreased action potential amplitude (APA) and maximal depolarization velocity (V(max)) and shortened action potential duration (APD), but did not alter the resting membrane potential (RMP). The demonstrated that the kinetics of sodium channel blockage by MFA resemble those of class I antiarrhythmic agents such as lidocaine. CONCLUSION: MFA protects the heart against arrhythmias by its blocking effect on sodium channels.

A Predictive Scoring System Based on Inflammatory and Tumor Markers for Gastric Cancer Patients Undergoing Curative Resection.

PURPOSE: Inflammation is closely associated with prognosis in gastric cancer (GC). We aimed to assess the predictive value of existing inflammatory and tumor markers in GC, to establish a systemic score based on valuable predictors for early risk stratification of patients, and to create a nomogram for individual risk prediction. PATIENTS AND METHODS: We retrospectively analyzed 401 GC patients who underwent curative gastrectomy from 2007 to 2016. RESULTS: Through univariate and multivariate survival analysis, age (>60 years), depth of invasion (pT3-4), lymph node invasion (pN1-3), histologic classification (poor), adjuvant chemotherapy (no), albumin fibrinogen ratio (AFR) (<13.33), and carbohydrate antigen 19-9 (CA19-9) (>27 U/mL) independently indicated inferior disease-free survival (DFS). In addition, depth of invasion, lymph node invasion, histologic classification, adjuvant chemotherapy, AFR, and CA19-9 were incorporated in the prediction of cancer-specific survival (CSS). A combined AFR and CA19-9 prognostic score (CACPS) was established. Lower AFR (<13.33) and higher CA19-9 (>27 U/mL) were allocated 1 point each in the CACPS (range, 0-2). CACPS can be used as an independent predictor for DFS and CSS in multivariate analysis (for DFS: CACPS 1: HR=2.039, 95% CI: 1.357-3.065, P=0.001; CACPS 2: HR=2.419, 95% CI: 1.397-4.186, P=0.002; for CSS: CACPS 1: HR=2.035, 95% CI: 1.292-3.205, P=0.002; CACPS 2: HR=2.255, 95% CI: 1.252-4.059, P=0.007), with a higher CACPS indicating poor survival according to Kaplan-Meier curves (both P<0.001). Moreover, a nomogram for DFS and CSS was generated using the significant characteristics in the multivariate analysis, which exhibited high accuracy (for DFS: C-index=0.743, 95% CI: 0.698-0.788; for CSS: C-index=0.766, 95% CI: 0.718-0.814) versus tumor-node-metastasis staging (for DFS: C-index=0.692, 95% CI: 0.650-0.734; for CSS: C-index=0.720, 95% CI: 0.675-0.764). CONCLUSION: Preoperative CACPS exhibited high accuracy in predicting prognosis for GC patients who underwent curative resection.

Curcumin, a Multi-Ion Channel Blocker That Preferentially Blocks Late Na+ Current and Prevents I/R-Induced Arrhythmias.

Increasing evidence shows that Curcumin (Cur) has a protective effect against cardiovascular diseases. However, the role of Cur in the electrophysiology of cardiomyocytes is currently not entirely understood. Therefore, the present study was conducted to investigate the effects of Cur on the action potential and transmembrane ion currents in rabbit ventricular myocytes to explore its antiarrhythmic property. The whole-cell patch clamp was used to record the action potential and ion currents, while the multichannel acquisition and analysis system was used to synchronously record the electrocardiogram and monophasic action potential. The results showed that 30 µmol/L Cur shortened the 50 and 90% repolarization of action potential by 17 and 7%, respectively. In addition, Cur concentration dependently inhibited the Late-sodium current (I Na.L), Transient-sodium current (I Na.T), L-type calcium current (I Ca.L), and Rapidly delayed rectifying potassium current (I Kr), with IC50 values of 7.53, 398.88, 16.66, and 9.96 µmol/L, respectively. Importantly, the inhibitory effect of Cur on I Na.L was 52.97-fold higher than that of I Na.T. Moreover, Cur decreased ATX II-prolonged APD, suppressed the ATX II-induced early afterdepolarization (EAD) and Ca2+-induced delayed afterdepolarization (DAD) in ventricular myocytes, and reduced the occurrence and average duration of ventricular tachycardias and ventricular fibrillations induced by ischemia-reperfusion injury. In conclusion, Cur inhibited I Na.L, I Na.T, I Ca.L, and I Kr; shortened APD; significantly suppressed EAD and DAD-like arrhythmogenic activities at the cellular level; and exhibited antiarrhythmic effect at the organ level. It is first revealed that Cur is a multi-ion channel blocker that preferentially blocks I Na.L and may have potential antiarrhythmic property.

Modulation of K(ATP) currents in rat ventricular myocytes by hypoxia and a redox reaction.

AIM: The present study investigated the possible regulatory mechanisms of redox agents and hypoxia on the K(ATP) current (I(KATP)) in acutely isolated rat ventricular myocytes. METHODS: Single-channel and whole-cell patch-clamp techniques were used to record the K(ATP) current (I(KATP)) in acutely isolated rat ventricular myocytes. RESULTS: Oxidized glutathione (GSSG, 1 mmol/L) increased the I(KATP), while reduced glutathione (GSH, 1 mmol/L) could reverse the increased I(KATP) during normoxia. To further corroborate the effect of the redox agent on the K(ATP) channel, we employed the redox couple DTT (1 mmol/L)/H2O2 (0.3, 0.6, and 1 mmol/L) and repeated the previous processes, which produced results similar to the previous redox couple GSH/GSSG during normoxia. H2O2 increased the I(KATP) in a concentration dependent manner, which was reversed by DTT (1 mmol/L). In addition, our results have shown that 15 min of hypoxia increased the I(KATP), while GSH (1 mmol/L) could reverse the increased I(KATP). Furthermore, in order to study the signaling pathways of the I(KATP) augmented by hypoxia and the redox agent, we applied a protein kinase C(PKC) inhibitor bisindolylmaleimide VI (BIM), a protein kinase G(PKG) inhibitor KT5823, a protein kinase A (PKA) inhibitor H-89, and Ca2+/calmodulin-dependent protein kinase II (CaMKII) inhibitors KN-62 and KN-93. The results indicated that BIM, KT5823, KN-62, and KN-93, but not H-89, inhibited the I(KATP) augmented by hypoxia and GSSG; in addition, these results suggest that the effects of both GSSG and hypoxia on K(ATP) channels involve the activation of the PKC, PKG, and CaMK II pathways, but not the PKA pathway. CONCLUSION: The present study provides electrophysiological evidence that hypoxia and the oxidizing reaction are closely related to the modulation of I(KATP).

Quercetin activates human Kv1.5 channels by a residue I502 in the S6 segment.

1. The aims of the present study were to investigate the pharmacological effects of quercetin on wild-type (WT) and mutant (I502A) human (h) Kv1.5 channel currents (I(kur)) and to identify whether mutation in the S6 segment is critical to activation of I(kur) by quercetin. 2. Experiments were performed on WT and site-directed mutant hKv1.5 channels, which were stably expressed in Xenopus oocytes using the two-microelectrode voltage-clamp technique. 3. Quercetin increased WT hKv1.5 channel current in a concentration-, voltage- and time-dependent manner, with an EC(50) of 37.8 micromol/L and a negative shift in the steady state activation and inactivation curves. Quercetin accelerated channel activation and inactivation, significantly decreasing activation and inactivation time constants. However, mutating the I502 residue to Ala abolished the activating effect of quercetin. Quercetin did not modify the activation and inactivation kinetics of I502A channels. As an anti-oxidant, tanshinone IIA (4 micromol/L) inhibited the H(2)O(2)-induced activation of WT hKv1.5 channels. In contrast, quercetin had no significant effect. 4. We conclude that: (i) quercetin preferentially binds to and increases the current amplitude of WT hKv1.5 channels; (ii) Ile502, an aliphatic and neutral amino acid residue residing in the S6 segment, is important in quercetin binding; and (iii) quercetin-induced changes in the properties of WT hKv1.5 channels may be foreign to its own anti-oxidant action.

Emerging Role for Exosomes in the Progress of Stem Cell Research.

Exosomes are small secretory vesicles that are involved in intercellular communication. Exosomes are secreted by many types of cells and exert important functions in plasma-membrane exchange as well as the transport of bioactive substances, such as proteins, messenger ribonucleic acids (mRNAs), micro ribonucleic acids (miRNAs) and organelles. Exosomes may regulate physiological processes by altering gene regulatory networks or epigenetic recombination. Recent studies have shown that exosomes secreted by stem cells can effectively transport proteins, mRNAs and miRNAs and play important roles in the regulation of tissue regeneration. This report reviews current progress in exosome studies as well as their emerging roles in stem cell research and potential clinical use.

[Low extracellular pH increases the persistent sodium current in guinea pig ventricular myocytes].

Whole-cell and cell-attached patch-clamp techniques were used to record the changes of persistent sodium current (I(Na.P)) in ventricular myocytes of guinea pig to investigate the effect of low extracellular pH on I(Na.P) and its mechanism. The results showed that low extracellular pH (7.0, 6.8 and 6.5) obviously increased the amplitude of whole-cell I(Na.P) in a [H(+)] concentration-dependent manner. Under the condition of extracellular pH 6.5, I(Na.P) was markedly augmented from control (pH 7.4) value of (0.347+/-0.067) pA/pF to (0.817+/- 0.137) pA/pF (P<0.01, n=6), whereas the reducing agent dithiothreitiol (DTT, 1 mmol/L) reversed the increased IN(Na.P) from (0.817+/-0.137) pA/pF to (0.233+/-0.078) pA/pF (P<0.01 vs pH 6.5, n=6). Decreasing extracellular pH to 6.5 also increased the persistent sodium channel activity in cell-attached patches. The mean open probability and mean open time were increased from control value of 0.021+/-0.007 and (0.899+/-0.074) ms to 0.205+/-0.023 and (1.593+/-0.158) ms, respectively (both P<0.01, n=6), and such enhancement was reversed by application of 1 mmol/L DTT [to 0.019+/-0.005 and (0.868+/-0.190) ms, both P<0.01 vs pH 6.5, n=6]. Furthermore, protein kinase C (PKC) inhibitor bisindolylmaleimide (BIM, 5 micromol/L) reduced the enhanced mean open probability and mean open time at pH 6.5 from 0.214+/-0.024 and (1.634+/-0.137) ms to 0.025+/-0.006 and (0.914+/-0.070) ms, respectively (both P<0.01 vs pH 6.5, n=6). The results demonstrate that low extracellular pH markedly increases I(Na.P) in guinea pig ventricular myocytes, in which activation of PKC may be involved.