Ligand-Accelerated Pd-Catalyzed C(sp2)-H and C(sp3)-H Arylation under the Catalytic System.

It is universally acknowledged that ligands can improve the reaction activity to simplify the reaction operating conditions and enrich the applicability of the reaction. Therefore, we developed N-octylglycine ligand-accelerated Pd-catalyzed ortho-arylation of benzoic acids under mild conditions with just 6 h; moreover, this N-octylglycine ligand was successfully implemented to carboxyl-directed Pd-catalyzed ß-C(sp3)-H arylation and ortho-arylation of phenylacetic acids under mild conditions.

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.

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.

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.

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.

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.

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.

Effects of ivabradine on cardiac electrophysiology in dogs with age-related atrial fibrillation.

BACKGROUND: Ivabradine is an inhibitor of mixed Na+-K+ current that could combine with HCN channels to reduce the transmembrane velocity of funny current (If), heart rate, and cardiac efficiency, and thus be used for the treatment of cardiovascular diseases such as chronic heart failure. As an ion channel blocker, Ivabradine is also a potential antiarrhythmic agent. MATERIAL/METHODS: Twelve aging dogs (8-10 years old) underwent rapid atrial pacing for 2 months to induce age-related AF in this study. The dogs were randomly divided into the Ivabradine group and aging-AF group. The effects of Ivabradine on the electrophysiological parameters, including the effective refractory period (ERP) of the pulmonary veins and atrium, duration of AF, and inducing rate of AF, were investigated. RESULTS: As compared to the aging-AF group, the ERPs of the left superior pulmonary vein (139.00±4.18 ms vs. 129.00±4.08 ms, P=0.005) and left auricle (135.00±3.53 ms vs. 122.00±4.47 ms, P=0.001) were significantly increased, while the duration of AF (46.60±5.07 s vs. 205.40±1.14 s, P=0.001) and inducing rate of AF (25% vs. 60%, P=0.001) were significantly decreased. CONCLUSIONS: Ivabradine could effectively reduce the inducing rate of AF, and thus be used as an upstream drug for the prevention of age-related AF.

Association between reversal in the expression of hyperpolarization-activated cyclic nucleotide-gated (HCN) channel and age-related atrial fibrillation.

BACKGROUND: We compared cardiac electrophysiological indicators and regional expression levels of cardiac hyperpolarization-activated cyclic nucleotide-gated (HCN) channels between adult and aged dogs to identify possible mechanisms of age-related atrial fibrillation. MATERIAL/METHODS: Corrected sinus node recovery time (SNRTc) and effective refractory period (ERP) of the atrium and pulmonary veins were measured in 10 adult (3-6 years old) and 10 aged dogs (>9 years old). Expression levels of HCN2 and HCN4 channel mRNAs and proteins were measured in the sinoatrial node, atrium, and pulmonary veins by real-time PCR and Western blotting. RESULTS: Aged dogs exhibited a higher induction rate of atrial fibrillation (AF) in response to electrical stimulation, longer AF duration after induction, longer SNRTc, longer right atrial effective refractory period (AERP), shorter left AERP, and increased AERP dispersion compared to adults. Expression levels of HCN2 and HCN4 channel mRNAs and proteins were lower in the sinoatrial node but higher in the atrium and pulmonary veins of aged dogs. CONCLUSIONS: Changes in atrial electrophysiological indicators in aged dogs revealed sinoatrial node dysfunction. There was a reversal in the local tissue distribution of HCN2 and HCN4 channel mRNA and protein, a decrease in sinoatrial node expression, and increase in atrial and pulmonary vein expression with age. Changes in atrial electrophysiological characteristics and regional HCN channel expression patterns were associated with the onset and maintenance of age-related atrial fibrillation.

Methyl 3-phenyl-isoxazole-5-carboxyl-ate.

In the title compound, C11H9NO3, the dihedral angle between the isoxazole and phenyl rings is 19.79 (12), while the ester group is inclined to the isoxazole group by 12.14 (6)°. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds, forming layers lying parallel to (010).

[Application experience of attain ® select II catheter delivery system for left ventricular lead implantation in cardiac resynchronization therapy].

OBJECTIVE: To summarize application experience of attain ® select II catheter delivery system for left ventricular lead implantation in cardiac resynchronization therapy (CRT). METHODS: CRT/CRT-D was applied for 86 patients with congestive heart failure and left bundle-branch block. Left ventricular lead implantation was applied without use of attain ® select II catheter delivery system in 42 patients without coronary vein anatomy variation (group A). Coronary sinus and cardiac vein angiography detected coronary vein anatomy variations in 44 patients and attain ® select II catheter delivery system was not used in 21 patients (group B) and used in 23 patients (group C). Total procedure time, LV lead implantation time, X-ray exposure time and complications were compared among groups. The optimal LV lead location were observed at the end of procedure. RESULTS: Patients were followed up to 245 days (160 - 368 days). Total procedure time [(119 ± 18) min vs. (142 ± 17) min; (119 ± 18) min vs. (143 ± 17) min], LV lead implantation time [(32 ± 7) min vs. (49 ± 8) min;(32 ± 7) min vs. (51 ± 7) min]and X-ray exposure time [(27 ± 6) min vs. (46 ± 84) min;(27 ± 6) min vs. (45 ± 7) min] were significant reduced in group C compared to group A and B. Procedure-related complications were similar among the 3 groups. The rate of optimal LV lead location was significantly higher in group C than in group B (96% vs. 71%). CONCLUSIONS: It is feasible and safe to implant LV lead through coronary sinus with attain ® select II catheter delivery system. Applying Attain ® select II catheter delivery system can improve the rate of optimal LV lead location with coronary venous anatomy variation.

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.

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.

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.

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.

[Differential expression of collagen and matrix metalloproteinases between left and right atria in patients with chronic atrial fibrillation.].

The present study aimed to investigate the mRNA expression levels of collagen, matrix metalloproteinases (MMPs), and tissue inhibitors of metalloproteinases (TIMPs) in the left and right atria in patients with chronic atrial fibrillation (CAF). Forty five patients with valvular heart disease were sampled in this study, including 18 patients with sinus rhythm (SR), 27 patients with CAF. Clinical data of these patients were collected, and the left and right atrial appendages were obtained from these patients during heart valvular replacement surgery. The mRNA levels of collagen type I, collagen type III, MMP1, MMP9, TMP1 of the atria were then measured by semi-quantitative RT-PCR. The results obtained were as follows. Compared to those in SR group, in atria of CAF group, the mRNA levels of collagen type I, MMP1 and MMP9 increased (P<0.05), while the mRNA level of TMP1 decreased (P<0.01). There were no significant differences in the mRNA levels of collagen type I, collagen type III, MMP1, MMP9 and TMP1 between the left and right atria of SR group (P>0.05). In CAF group, the mRNA level of MMP1 in the right atrium was higher than that in the left atrium (P<0.05), however, the mRNA level of MMP9 in the left atrium was higher than that in the right atrium (P<0.01). In both the left and right atria, the mRNA of collagen type I was positively correlated with the corresponding atrial diameter; the mRNA of MMP1 and MMP9 was positively correlated with the mRNA of collagen type I, and was negatively correlated with the mRNA of TMP1. These results suggest that the increased level of collagen type I associated with selective upregulation of MMP1, 9 and downregulation of TMP1, 9 in the atrium might be the molecular basis of atrial interstitial fibrosis in patients with CAF. Moreover, during CAF development, there is difference in the expression of MMPs between the left and right atria.

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.