Ligand Promoted Pd-Catalyzed High para-Selective C-H Olefination.

Achieving high para-selective C-H functionalized products of benzoic acid derivatives using a designed template is still a daunting challenge because the carbonyl group also could coordinate with metal to activate the ortho-C-H bond. Herein, we report the ligand promoted high para-selective C-H olefination of benzoic acid derivatives; we screened a series of ligands increasing the ratio of p:others from 62:38 to 96:4. This work may find application in the construction of para-substituted benzoic acid derivatives.

Study of the optimum fluoroscopic angle for the implant fixation test of a leadless cardiac pacemaker.

The Micra TPS™ (Medtronic) is the first leadless pacemaker listed in China. The best fluoroscopic angle for the intraoperative fixation test is selected according to different implantation sites to reduce the fluoroscopy duration and radiation dose, and the test is based on the early safety and effectiveness of the device after implantation. A total of 110 patients who underwent Micra TPS™ implantation were selected. Eighty patients were in group A, and 30 patients were in group B. Under the guidance of the conclusions from group A, the fluoroscopy duration, radiation dose and number of fluoroscopic positions of the best fluoroscopic angle of the fixation test according to different positions of the implanted interventricular septum were compared. In 85.0% of the group A implants, these angles were based on the right interior oblique (RAO) angle, with 48.5% cranial (CRA) and 29.4% caudal (CAU) angles. The angle of the tilting head side of the RAO angle was prioritized in group B, and referring to the average angle data, the average fluoroscopy duration for finding the best angle of fixation test was 1.7 ± 0.6 vs. 3.2 ± 1.8 min (P < 0.001), the average radiation dose was 270.4 ± 56.3 vs. 338.1 ± 112.9 mGy (P = 0.002), and the average number of fluoroscopic positions was 2.2 ± 0.6 vs. 4.2 ± 2.1 (P < 0.001), which was significantly less than that in group A. This study found that there was regularity in the fluoroscopic angle for the fixation test during Micra TPS™ operation.Level of Evidence Level 3, local nonrandom sample.

Aging-induced atrial fibrosis in If current change and its effect on atrial fibrillation in dogs.

BACKGROUND: Atrial fibrillation (AF) is a very common type of cardiac arrhythmia that threatens public health. Aging is an independent AF risk factor. However, the mechanism of age-related AF remains unclear. METHODS: A total of 36 Beagle dogs were selected and divided into three groups (12 in each group): two groups were 9-year-old aged dogs, and one group was 4-year-old adult dogs. Electrophysiological testing was employed to determine if modeling is successful. Patch-clamp technique was employed to measure the If current. The expression of protein and mRNA related to If current were also tested. Collagen deposition was observed with the use of Masson staining. RESULTS: Aging resulted in a higher collagen deposition percentage in the left atrium. The hyperpolarization-activated cyclic nucleotide-gated (HCN)2 and HCN4 expressions were increased in the atria and pulmonary veins but decreased in the sinus node of the aged group. Moreover, in the aged group, the left atrium mRNA expressions of Kcnd2 (Potassium voltage-gated channel subfamily D member 2), Kcnh2, Kcnq1, Kcnj2, Kcnj11, and CACNA1H were significantly downregulated. The aged AF group also demonstrated sustained AF and significant changes in electrophysiological characteristics. The If current demonstrated an increased amplitude and was easier to activate in the aged AF group than in younger group. Finally, AF occurrence exacerbated aging-induced cardiac fibrosis, thereby aggravating the above-listed symptoms. CONCLUSION: With age, the increase in atrial fibrosis affected the expression of the ion channels, thereby modulating the If current. Moreover, AF also further exacerbated the degree of atrial fibrosis.

Incidence, Risk Factors, and Prognosis of Tricuspid Regurgitation After Cardiac Implantable Electronic Device Implantation: A Systematic Review and Meta-analysis.

This study aimed to determine the pooled incidence, risk factors, and clinical prognosis of tricuspid regurgitation (TR) deterioration after implantation of a cardiac implantable electronic device (CIED). The study was designed as a meta-analysis of randomized controlled trials and observational studies. Patients with indications for CIEDs were selected as participants and CIED implantation was the intervention. PubMed, EMBASE, the Cochrane Library, China National Knowledge Infrastructure, Wanfang Data, and China Science and Technology Journal Database were searched systematically to identify studies. Thirty-seven studies with 8,144 patients were included. The pooled incidence of TR deterioration of at least one grade was 25.1% (95% confidence interval [CI], 20.9-29.3; Z = 11.60; p < 0.01; I2 = 94.8%, p < 0.01). Compared with TR incidence after permanent pacemaker implantation, that after implantable cardioverter-defibrillator implantation did not significantly increase (22.68% v 29.18%; odds ratio [OR], 0.615; 95% CI, 0.271-1.339; Z =1.16; p = 0.246). The pooled incidence of TR deterioration of at least two grades was 9.4% (95% CI, 6.6-12.1; Z = 6.72; p < 0.01; I2 = 86.0%, p < 0.01). Lead interference (OR, 8.704; 95% CI,4.450-17.028; Z= 6.32; p < 0.001) and pacemaker implantation time (OR, 1.153; 95% CI, 1.082-1.229; Z = 4.37; p < 0.001) were risk factors for worsening TR. Baseline atrial fibrillation, age, baseline mild TR, and left ventricular ejection fraction were not associated with TR. All-cause mortality (>one year after pacemaker implantation) was higher in patients with TR deterioration (hazard ratio, 1.598; 95% CI, 1.275-2.002; Z = 4.07; p < 0.01; I2 = 0%). TR is a common complication after CIED implantation. Lead interference and pacemaker implantation time were risk factors for TR worsening. Compared with patients without TR deterioration after pacemaker implantation, patients with TR deterioration had a poorer prognosis.

Effects of Pacemaker Implantation on Sudden Cardiac Death Rate and Quality of Life in Atrial Fibrillation Patients With Ventricular Pauses.

Ventricular arrest is a rare arrhythmic disease in the clinic; 35% to 55% of cases are associated with atrial fibrillation (AF). It is well known that ventricular arrest for ≥3 seconds can lead to brain symptoms such as dizziness and even syncope, but it is not clear whether ventricular pauses (≥3 seconds) with AF will lead to sudden cardiac death. If the implantation of a pacemaker can improve the quality of life of patients with permanent AF with ventricular arrest and whether it has a long-term protective effect on sudden cardiac death. To this end, we conducted a prospective follow-up observation study, which was conducted through telephone interviews and clinical hospital observation to obtain information on the quality of life, survival rate, and other details. The results show that for patients with permanent AF with ventricular arrest, pacemaker implantation cannot reduce sudden cardiac death, cardiovascular events, and stroke nor can it improve the cumulative survival rate. Fortunately, the implantation of pacemakers can improve the quality of life of patients.

Enhanced atrial internal-external neural remodeling facilitates atrial fibrillation in the chronic obstructive sleep apnea model.

OBJECTIVE: Autonomic imbalance plays a crucial role in obstructive sleep apnea (OSA) associated atrial fibrillation (AF). Here, we investigated the potential neural mechanism of AF induced by OSA. METHODS: Ten dogs were divided into control group (n = 5) and OSA group (n = 5). The chronic OSA model was established by repeat apnea-ventilation cycles for 4 hours a day for 12 weeks. During the process of model establishment, arterial blood gases, atrial effective refractory period (AERP), AF inducibility, normalized low-frequency power (LFnu), normalized high-frequency power (HFnu), and LFnu/ HFnu were evaluated at baseline, 4th week, 8th week, and 12th week. Nerve activities of left stellate ganglion (LSG) and left vagal nerve(LVN) were recorded. Tyrosine hydroxylase(TH), choline acetyltransferase(CHAT), PGP9.5, nerve growth factor(NGF), and c-Fos were detected in the left atrium, LSG, and LVN by immunohistochemistry and western blot. Moreover, high-frequency stimulations of LSG and LVN were conducted to observe the AF inducibility. RESULTS: Compared with the control group, the OSA group showed significantly enhanced neural activity of the LSG, increased AF inducibility, and shortened AERP. LFnu and LFnu/HFnu were markedly increased in the OSA group, while no significant difference in HFnu was observed. TH-positive and PGP9.5-positive nerve densities were significantly increased in the LSG and left atrium. Additionally, the protein levels of NGF, c-Fos, and PGP9.5 were upregulated both in the LSG and left atrium. AF inducibility was markedly increased under LSG stimulation without a stimulus threshold change in the OSA group. CONCLUSIONS: OSA significantly enhanced LSG and left atrial neural remodeling, and hyperactivity of LSG may accelerate left atrial neural remodeling to increase AF inducibility.

KCNQ1 G219E and TRPM4 T160M polymorphisms are involved in the pathogenesis of long QT syndrome: A case report.

RATIONALE: Long QT syndrome (LQTS) is an inheritable disease characterized by prolonged QT interval on the electrocardiogram. The pathogenesis of LQTS is related to mutations in LQTS-susceptible genes encoding cardiac ion channel proteins or subunits. PATIENT CONCERNS: Here, we reported a 37-year-old female Uygur patient with palpitation and loss of consciousness. DIAGNOSES: At the time of admission, a 12-lead electrocardiogram showed a QTc interval of 514 ms. Genetic analysis revealed KCNQ1 G219E and TRPM4 T160M mutations. INTERVENTIONS: Although beta-blockers remain the mainstay in treating LQTS, the patient underwent implantation of an automatic cardioverter defibrillator due to life-threatening arrhythmias. OUTCOMES: To explore the effect of the calcium ion antagonist verapamil on ion channels, we generated human induced pluripotent stem cell cardiomyocytes (hiPSC-CMs) from the peripheral blood mononuclear cells of the patient. The changes of action potential duration in response to verapamil were observed. LESSONS: Our results showed that patient-derived hiPSC-CMs could recapitulate the electrophysiological features of LQTS and display pharmaceutical responses to verapamil.

A prospective comparison of four methods for preventing pacemaker pocket infections.

This study aims to evaluate four pacemaker pocket cleaning methods for preventing implantation-related infections. This single-center trial prospectively randomized 910 patients undergoing first-time pacemaker implantation or replacement into four pocket cleaning methods: hemocoagulase (group A, n = 228), gentamicin (group B, n = 228), hemocoagulase plus gentamicin (group C, n = 227), and normal saline (group D, n = 227). Before implanting the pacemaker battery, the pockets were cleaned with gauze presoaked in the respective cleaning solutions. Then, these patients were followed up to monitor the occurrence of infections for 1 month after implantation. Twelve implantation-related infections occurred in 910 patients (1.32%): four patients from group A (1.75%), three patients from group B (1.32%), two patients from group C (0.88%), and three patients from group D (1.32%) (P > .05). Furthermore, two patients developed bloodstream infections (0.22%), and both of these patients were associated with pocket infection (one patient was from group A, while the other patient was from group C, respectively). No cases of infective endocarditis occurred. The differences in the number of infections in these study groups were not statistically significant. The application of hemocoagulase, gentamicin, hemocoagulase plus gentamicin, or normal saline on the presoaked gauze before implantation was equally effective in preventing pocket-associated infections.

LDL-C/HDL-C is associated with ischaemic stroke in patients with non-valvular atrial fibrillation: a case-control study.

BACKGROUND: This study explored the relationships between the low-/high-density lipoprotein cholesterol ratio (LDL-C/HDL-C) and other clinical indicators and ischaemic stroke (IS) in patients with non-valvular atrial fibrillation (NVAF) in Xinjiang. The findings could provide a theoretical and therapeutic basis for NVAF patients. METHODS: NVAF patients who were admitted to 10 medical centres across Xinjiang were divided into stroke (798 patients) and control (2671 patients) groups according to the occurrence of first acute IS. Univariate and multivariate logistic regression analysis were used to examine the independent risk factors for IS in NVAF patients. Factor analysis and principal component regression analysis were used to analyse the main factors influencing IS. Receiver operating characteristic (ROC) curve analysis was used to evaluate the discriminatory ability of LDL-C/HDL-C for predicting the occurrence of IS. RESULTS: The stroke group had an average age of 71.64 ± 9.96 years and included 305 females (38.22%). The control group had a mean age of 67.30 ± 12.01 years and included 825 females (30.89%). Multivariate logistic regression showed that the risk of IS in the highest LDL-C/HDL-C quartile (≥2.73) was 16.23-fold that of the lowest quartile (< 1.22); IS risk was 2.27-fold higher in obese patients than in normal-weight subjects; IS risk was 3.15-fold higher in smoking patients than in non-smoking patients. The area under the ROC curve of LDL-C/HDL-C was 0.76, the optimal critical value was 2.33, the sensitivity was 63.53%, and the specificity was 76.34%. Principal component regression analysis showed that LDL-C/HDL-C, age, smoking, drinking, LDL-C and hypertension were risk factors for IS in NVAF patients. CONCLUSIONS: LDL-C/HDL-C > 1.22, smoking, BMI ≥24 kg/m2 and CHA2DS2-VASc score were independent risk factors for IS in NVAF patients; LDL-C/HDL-C was the main risk factor.

Intertwined dipolar and multipolar order in the triangular-lattice magnet TmMgGaO4.

A phase transition is often accompanied by the appearance of an order parameter and symmetry breaking. Certain magnetic materials exhibit exotic hidden-order phases, in which the order parameters are not directly accessible to conventional magnetic measurements. Thus, experimental identification and theoretical understanding of a hidden order are difficult. Here we combine neutron scattering and thermodynamic probes to study the newly discovered rare-earth triangular-lattice magnet TmMgGaO4. Clear magnetic Bragg peaks at K points are observed in the elastic neutron diffraction measurements. More interesting, however, is the observation of sharp and highly dispersive spin excitations that cannot be explained by a magnetic dipolar order, but instead is the direct consequence of the underlying multipolar order that is "hidden" in the neutron diffraction experiments. We demonstrate that the observed unusual spin correlations and thermodynamics can be accurately described by a transverse field Ising model on the triangular lattice with an intertwined dipolar and ferro-multipolar order.

Establishment of a predictive model for inpatient sudden cardiac death in a Chinese cardiac department population: a retrospective study.

BACKGROUND: Little is known about the risk factors for sudden cardiac death (SCD) in the overall hospitalized cardiac department population. This study was conducted to investigate the risk factors and develop a predictive model for SCD in a hospitalized cardiac department population. METHODS: We conducted a retrospective study of patients admitted to the cardiac department of the First Affiliated Hospital of Xinjiang Medical University from June 2015 to February 2017. We collected the clinical data from medical records. Multiple stepwise logistic regression analysis was carried out to confirm the risk factors for SCD and develop a predictive risk model. The risk score was assessed by the area under receiver operating characteristic (AUROC) curve and the Hosmer-Lemeshow goodness-of-fit test. RESULTS: A total of 262 patients with SCD and 4485 controls were enrolled in our study. Logistic regression modeling identified eight significant risk factors for in-hospital SCD: age, main admitting diagnosis, diabetes, corrected QT interval, QRS duration, ventricular premature beat burden, left ventricular ejection fraction, and estimated glomerular filtration rate. A predictive risk score including these variables showed an AUROC curve of 0.774 (95% confidence interval: 0.744-0.805). The Hosmer-Lemeshow goodness-of-fit test showed the chi-square value was 2.527 (P = 0.640). The incidence of in-hospital SCD was 1.3%, 4.1%, and 18.6% for scores of 0 to 2, 3 to 5 and ≥6, respectively (P < 0.001). CONCLUSIONS: Age, main admitting diagnosis, diabetes, QTc interval, QRS duration, ventricular premature beat burden, left ventricular ejection fraction, and estimated glomerular filtration rate are factors related to in-hospital SCD in a hospitalized cardiac department population. We developed a predictive risk score including these factors that could identify patients who are predisposed to in-hospital SCD.

Renal Denervation Reduced Ventricular Arrhythmia After Myocardial Infarction by Inhibiting Sympathetic Activity and Remodeling.

Background Ventricular arrhythmia after myocardial infarction is the most important risk factor for sudden cardiac death, which poses a serious threat to human health. As the correlation between autonomic nervous systemic dysfunction and heart rhythm abnormality has been gradually revealed, remedies targeting autonomic nervous system dysfunction, especially the sympathetic nerve, have emerged. Among them, renal denervation is noted for its powerful effect on the inhibition of sympathetic nerve activity. We aim to investigate whether renal denervation can reduce ventricular arrhythmia after myocardial infarction and thus decrease the risk of sudden cardiac death. In addition, we explore the potential mechanism with respect to nerve activity and remodeling. Methods and Results Twenty-four beagles were randomized into the control (n=4), renal denervation (n=10), and sham (n=10) groups. Permanent left anterior descending artery ligation was performed to establish myocardial infarction in the latter 2 groups. Animals in the renal denervation group underwent both surgical and chemical renal denervation. Compared with dogs in the sham group, dogs in the renal denervation group demonstrated attenuated effective refractory period shortening and inhomogeneity, flattened restitution curve, increased ventricular threshold, and decreased ventricular arrhythmia. Heart rate variability assessment, catecholamine measurement, and nerve discharge recordings all indicated that renal denervation could reduce whole-body and local tissue sympathetic tone. Tissue analysis revealed a significant decrease in neural remodeling in both the heart and stellate ganglion. Conclusions Surgical and chemical renal denervation decreased whole-body and local tissue sympathetic activity and reversed neural remodeling in the heart and stellate ganglion. Consequently, renal denervation led to beneficial remodeling of the electrophysiological characteristics in the infarction border zone, translating to a decrease in ventricular arrhythmia after myocardial infarction.

Fractionalized excitations in the partially magnetized spin liquid candidate YbMgGaO4.

Quantum spin liquids (QSLs) are exotic states of matter characterized by emergent gauge structures and fractionalized elementary excitations. The recently discovered triangular lattice antiferromagnet YbMgGaO4 is a promising QSL candidate, and the nature of its ground state is still under debate. Here we use neutron scattering to study the spin excitations in YbMgGaO4 under various magnetic fields. Our data reveal a dispersive spin excitation continuum with clear upper and lower excitation edges under a weak magnetic field (H = 2.5 T). Moreover, a spectral crossing emerges at the Γ point at the Zeeman-split energy. The corresponding redistribution of the spectral weight and its field-dependent evolution are consistent with the theoretical prediction based on the inter-band and intra-band spinon particle-hole excitations associated with the Zeeman-split spinon bands, implying the presence of fractionalized excitations and spinon Fermi surfaces in the partially magnetized QSL state in YbMgGaO4.

Prevention of Atrial Fibrillation by Using Sarcoplasmic Reticulum Calcium ATPase Pump Overexpression in a Rabbit Model of Rapid Atrial Pacing.

BACKGROUND Recent research suggests that abnormal Ca2+ handling plays a role in the occurrence and maintenance of atrial fibrillation (AF). Therefore, Ca2+ release and ingestion depend on properties of the ryanodine receptor (RyR) and sarcoplasmic reticulum Ca2+ATPase2a (SERCA2a). This study aimed to detect whether SERCA2a gene overexpression has a preventive effect on atrial fibrillation caused by rapid pacing right atrium. MATERIAL AND METHODS Forty-eight New Zealand white rabbits were randomly divided into a control group, AF group, AAV9/GFP group, and AAV9/SERCA2a group. The right atrium was rapidly paced at 600 beats/min for 30 days after an intraperitoneal injection of an adeno-associated virus expressing the SERCA2a gene and GFP. The AF induction rate and the effective refraction period (ERP) were measured after 0, 4, 8, 12, and 24 h of pacing. Western blot analysis was used to test for the expression of SERCA2a. Changes in atrial tissue structure were observed by H&E staining and electron microscopy. RESULTS The AF induction rate was higher in the AF groups than in the AAV9/SERCA2a group at different time points of pacing. After 12 h of pacing, ERP was significantly prolonged in the AAV9/SERCA2a group compared to the AF and AAV9/GFP groups (p<0.05). SERCA2a protein expression was significantly lower in the AF and AAV9/GFP groups compared to the control group (p<0.05), while expression was significantly higher in the AAV9/SERCA2a group than in the AF and AAV9/GFP groups (p<0.05). The myocardial structure of the AAV9/SERCA2a group was significantly improved compared with the AF group, indicating that SERCA2a overexpression relieved the structural remodeling of atrial fibrillation. CONCLUSIONS SERCA2a overexpression is capable of suppressing ERP shortening and AF induced by rapid pacing atrium. SERCA2a gene therapy is expected to be a new anti-atrial fibrillation strategy.

Increase of Autonomic Nerve Factors in Epicardial Ganglionated Plexi During Rapid Atrial Pacing Induced Acute Atrial Fibrillation.

BACKGROUND The cardiac autonomic nervous system plays an essential role in epicardial ganglionated plexi (GP) regulation of atrial fibrillation onset and progression. To date, the activity of GP and the function of the cardiac autonomic nervous system are not well understood. The aim of this study was to determine alterations in epicardial GP cholinergic nerve, adrenergic nerve, and nerve growth factor expression using rapid atrial pacing to induce atrial fibrillation in canines. MATERIAL AND METHODS Nine healthy adult beagles were divided into two groups: the pacing experimental group (n=6) and the sham-operation control group (n=3). For the pacing group, high frequency pacing of the left atrial appendage was performed for eight hours. In the control group, electrodes were implanted without rapid atrial pacing. Immunocytochemistry was used to identify neurons positively expressing tyrosine hydroxylase, choline acetyl transferase, nerve growth factor and neurturin. RESULTS After successfully establishing a rapid atrial pacing of the left atrial appendage induced atrial fibrillation model, we found that expression of choline acetyl transferase, tyrosine hydroxylase, nerve growth factor, and neurturin was significantly higher in the rapid atrial pacing group than the control group (p<0.05). CONCLUSIONS In our model, incremental excitability of both the adrenergic and cholinergic nerves led to frequent incidents of atrial fibrillation, which were possibly due to an imbalance of autonomic nerve factors in the epicardial GP during acute atrial fibrillation.

Evidence for a spinon Fermi surface in a triangular-lattice quantum-spin-liquid candidate.

A quantum spin liquid is an exotic quantum state of matter in which spins are highly entangled and remain disordered down to zero temperature. Such a state of matter is potentially relevant to high-temperature superconductivity and quantum-information applications, and experimental identification of a quantum spin liquid state is of fundamental importance for our understanding of quantum matter. Theoretical studies have proposed various quantum-spin-liquid ground states, most of which are characterized by exotic spin excitations with fractional quantum numbers (termed 'spinons'). Here we report neutron scattering measurements of the triangular-lattice antiferromagnet YbMgGaO4 that reveal broad spin excitations covering a wide region of the Brillouin zone. The observed diffusive spin excitation persists at the lowest measured energy and shows a clear upper excitation edge, consistent with the particle-hole excitation of a spinon Fermi surface. Our results therefore point to the existence of a quantum spin liquid state with a spinon Fermi surface in YbMgGaO4, which has a perfect spin-1/2 triangular lattice as in the original proposal of quantum spin liquids.

Weyl magnons in breathing pyrochlore antiferromagnets.

Frustrated quantum magnets not only provide exotic ground states and unusual magnetic structures, but also support unconventional excitations in many cases. Using a physically relevant spin model for a breathing pyrochlore lattice, we discuss the presence of topological linear band crossings of magnons in antiferromagnets. These are the analogues of Weyl fermions in electronic systems, which we dub Weyl magnons. The bulk Weyl magnon implies the presence of chiral magnon surface states forming arcs at finite energy. We argue that such antiferromagnets present a unique example, in which Weyl points can be manipulated in situ in the laboratory by applied fields. We discuss their appearance specifically in the breathing pyrochlore lattice, and give some general discussion of conditions to find Weyl magnons, and how they may be probed experimentally. Our work may inspire a re-examination of the magnetic excitations in many magnetically ordered systems.

TNNT2 Gene Polymorphisms are Associated with Susceptibility to Idiopathic Dilated Cardiomyopathy in Kazak and Han Chinese.

BACKGROUND: Dilated cardiomyopathy (DCM) is characterized by left ventricular enlargement, systolic dysfunction, and heart failure. Both genetic and non-genetic factors have been linked to DCM pathogenesis. Familial DCM (FDCM) accounts for 20%-50% of all DCM cases, highlighting the importance of genetics in pathogenesis. Indeed, more than 40 DCM-associated genes have been identified, including the gene encoding cardiac troponin T type-2 (TNNT2). We examined polymorphisms of the TNNT2 gene in idiopathic DCM (IDCM) patients of Kazak and Han ethnicity compared with healthy Kazak and Han controls. MATERIAL AND METHODS: Peripheral blood samples were collected from 180 patients with IDCM (90 Kazak and 90 Han), and 180 healthy controls (90 Kazak and 90 Han). PCR was used to amplify 15 exons and nearby introns of the TNNT2 gene. The amplified products were sequenced and compared to the standard sequence in PubMed by BLAST and CHROMAS software, to identify mutation sites. RESULTS: Results from Kazak and Han IDCM patients were complied for Hardy-Weinberg equilibrium analysis. There was a significant difference in the genotype distribution (χ2=6.67, P=0.015) and allele frequency (χ2=5.71, P=0.017) between Kazaks with IDCM and Kazak controls of SNP rs3729547. There was also a difference in the genotype distribution (χ2=6.62, P=0.036) and allele frequency (χ2=4.91, P=0.018) between Han with IDCM and Han controls. The TNNT2 gene polymorphism loci rs3729547 may be associated with the IDCM onset in Kazak and Han patients (OR=2.5, 95% CI: 1.233~5.068). CONCLUSIONS: The TNNT2 polymorphisms might play an important role in susceptibility to DCM in Xinjiang Kazak and Han patients.

Altered expression of hyperpolarization-activated cyclic nucleotide-gated channels and microRNA-1 and -133 in patients with age-associated atrial fibrillation.

Hyperpolarization-activated cyclic nucleotide-gated (HCN) cation channels mediate pacemaker currents in the atrium. The microRNA (miR) families miR-1 and miR-133 regulate the expression of multiple genes involved in myocardial function, including HCN channels. It was hypothesized that age­dependent changes in HCN2, HCN4, miR­1 and miR­133 expression may contribute to age­associated atrial fibrillation, and therefore the correlation between expression levels, among adult (≤65 years) and aged patients (≥65 years), and sinus rhythm was determined. Right atrial appendage samples were collected from 60 patients undergoing coronary artery bypass grafting. Reverse transcription-quantitative polymerase chain reaction (PCR) and western blot analyses were performed in order to determine target RNA and protein expression levels. Compared with aged patients with sinus rhythm, aged patients with atrial fibrillation exhibited significantly higher HCN2 and HCN4 channel mRNA and protein expression levels (P<0.05), but significantly lower expression levels of miR­1 and miR­133 (P<0.05). In addition, aged patients with sinus rhythm exhibited significantly higher expression levels of HCN2 and HCN4 channel mRNA and protein (P<0.05), but significantly lower expression levels of miR­1 and ­133 (P<0.05), compared with those of adult patients with sinus rhythm. Expression levels of HCN2 and HCN4 increased with age, and a greater increase was identified in patients with age­associated atrial fibrillation compared with that in those with aged sinus rhythm. These electrophysiological changes may contribute to the induction of ectopic premature beats that trigger atrial fibrillation.