Dact1 involvement in the cytoskeletal arrangement of cardiomyocytes in atrial fibrillation by regulating cx43

Abstract Objective: To determine the role of the dishevelled binding antagonist of beta catenin 1 (DACT1) in the cytoskeletal arrangement of cardiomyocytes in atrial fibrillation (AF). Methods: The DACT1 expression and its associations with the degree of fibrosis and β-catenin in valvular disease patients were analyzed by immunohistochemistry and Masson's staining. DACT1 was overexpressed in the atrial myocyte cell line (HL-1) and the cardiac cell line (H9C2) by adenoviral vectors. Alterations in the fibrous actin (F-actin) content and organization and the expression of β-catenin were detected by flow cytometry, immunofluorescence, and Western blotting. Additionally, the association of DACT1 with gap junctions connexin 43 (Cx43) was detected by immunohistochemistry, immunofluorescence, and Western blotting. Results: Decreased cytoplasmic DACT1 expression in the myocardium was associated with AF (P=0.037) and a high degree of fibrosis (weak vs. strong, P=0.028; weak vs. very strong, P=0.029). A positive association was observed between DACT1 and β-catenin expression in clinical samples (P=0.028, Spearman's rho=0.408). Furthermore, overexpression of DACT1 in HL-1 and H9C2 cells induced an increase in β-catenin and subsequent partial colocalization of DACT1 and β-catenin. In addition, F-actin content and organization were enhanced. Interestingly, DACT1 was positively correlated with the Cx43 expression in clinical samples (P=0.048, Spearman's rho=0.370) and changed the Cx43 distribution in cardiac cell lines. Conclusion: DACT1 proved to be a novel AF-related gene by regulating Cx43 via cytoskeletal organization induced by β-catenin accumulation in cardiomyocytes. DACT1 could thus serve as a potential therapeutic marker for AF.

Novel biomarkers in cardiology: MicroRNAs in atrial fibrillation / Nuevos biomarcadores en cardiología: microARN en fibrilación auricular

Atrial fibrillation (AF) is the most common sustained chronic cardiac arrhythmia in clinical practice, which increases the risk of stroke and thromboembolism and is an independent predictor of mortality. The underlying mechanisms involved in the development of AF have yet to be fully elucidated. However, once initiated, AF tends to self-perpetuate, owing to structural and electrical remodeling in the atria. MicroRNAs (miRNAs) represent a sizable sub-group of small non-coding RNAs, which degrades or inhibits the translation of their target mRNAs, thus regulating gene expression and playing an important role in a wide range of biologic processes. Clinically, there is increasing evidence of the potential diagnostic role of miRNAs as biomarkers, representing a novel therapeutic target in AF. The aim of this review is to provide an exhaustive overview of the role of miRNAs in AF and to discuss the diagnostic and therapeutic potential of miRNAs in this arrhythmia.

La fibrilación auricular (FA) es la arritmia cardíaca sostenida crónica más común en la práctica clínica, lo que aumenta el riesgo de accidente cerebrovascular y tromboembolismo, y es un predictor independiente de mortalidad. Los mecanismos subyacentes implicados en el desarrollo de la FA todavía no se han aclarado completamente. Sin embargo, una vez iniciada, la FA tiende a perpetuarse, debido al remodelado estructural y eléctrico en la aurícula. Los microARN (miARN) representan un subgrupo importante de pequeños ARN no codificantes, que degradan o inhiben la traducción de sus ARN mensajeros diana, regulando así la expresión génica y que desempeñan un papel importante en una amplia gama de procesos biológicos. Clínicamente, se ha observado con creciente interés el posible papel diagnóstico de los miARN como biomarcadores, representando una nueva diana terapéutica en la FA. El objetivo de esta revisión es proporcionar una visión exhaustiva de la función de los miARN en la FA y discutir el posible papel diagnóstico y terapéutico de los miARN en esta arritmia.

Benefits of maltodextrin intake 2 hours before cholecystectomy by laparotomy in respiratory function and functional capacity: a prospective randomized clinical trial / Benefícios na função respiratória e capacidade funcional com ingesta de maltodextrina 2 horas antes de colecistectomia por laparotomia: ensaio clínico prospectivo e randomizado

ABSTRACT Objective: To evaluate the change in respiratory function and functional capacity according to the type of preoperative fasting. Methods: Randomized prospective clinical trial, with 92 female patients undergoing cholecystectomy by laparotomy with conventional or 2 hours shortened fasting. The variables measured were the peak expiratory flow, forced expiratory volume in the first second, forced vital capacity, dominant handgrip strength, and non-dominant handgrip strength. Evaluations were performed 2 hours before induction of anesthesia and 24 hours after the operation. Results: The two groups were similar in preoperative evaluations regarding demographic and clinical characteristics, as well as for all variables. However, postoperatively the group with shortened fasting had higher values than the group with conventional fasting for lung function tests peak expiratory flow (128.7±62.5 versus 115.7±59.9; p=0.040), forced expiratory volume in the first second (1.5±0.6 versus 1.2±0.5; p=0.040), forced vital capacity (2.3±1.1 versus 1.8±0.9; p=0.021), and for muscle function tests dominant handgrip strength (24.9±6.8 versus 18.4±7.7; p=0.001) and non-dominant handgrip strength (22.9±6.3 versus 17.0±7.8; p=0.0002). In the intragroup evaluation, there was a decrease in preoperative compared with postoperative values, except for dominant handgrip strength (25.2±6.7 versus 24.9±6.8; p=0.692), in the shortened fasting group. Conclusion: Abbreviation of preoperative fasting time with ingestion of maltodextrin solution is beneficial to pulmonary function and preserves dominant handgrip strength. .

RESUMO Objetivo: Avaliar a alteração da função respiratória e da capacidade funcional, conforme o tipo de jejum pré-operatório. Métodos: Ensaio clínico prospectivo randomizado, com 92 pacientes do sexo feminino, submetidas à colecistectomia por laparotomia, observando jejum convencional ou abreviado de 2 horas com maltodextrina. As variáveis foram: pico de fluxo expiratório, volume expiratório no primeiro segundo, capacidade vital forçada, força de preensão palmar dominante e força de preensão palmar não dominante. As avaliações foram realizadas 2 horas antes da indução anestésica e 24 horas após a operação. Resultados: Os dois grupos foram semelhantes quanto às características demográficas, clínicas e em todas as variáveis estudadas, quando avaliadas no pré-operatório. No entanto, no pós-operatório, o grupo abreviado apresentou valores maiores que o grupo convencional para pico de fluxo expiratório (128,7±62,5 versus 115,7±59,9; p=0,040), volume expiratório no primeiro segundo (1,5±0,6 versus 1,2±0,5; p=0,040), capacidade vital forçada (2,3±1,1 versus 1,8±0,9; p=0,021), força de preensão palmar dominante (24,9±6,8 versus 18,4±7,7; p=0,001) e força de preensão palmar não dominante (22,9±6,3 versus 17,0±7,8; p=0,0002). Na avaliação intragrupo, houve diminuição nas variáveis ao se compararem os valores do pré-operatório em relação ao pós-operatório, exceto para força de preensão palmar dominante (25,2±6,7 versus 24,9±6,8; p=0,692) no grupo de jejum abreviado. Conclusão: A abreviação do tempo de jejum pré-operatório com solução contendo maltodextrina beneficia a função pulmonar e preserva a força de preensão palmar dominante. .

eNOS3 Genetic Polymorphism Is Related to Post-Ablation Early Recurrence of Atrial Fibrillation

PURPOSE: Previous studies have demonstrated an association between eNOS polymorphisms and atrial fibrillation (AF). We sought to determine whether eNOS polymorphisms are associated with AF recurrence after a radiofrequency catheter ablation (RFCA). MATERIALS AND METHODS: A total of 500 consecutive patients (56+/-11 years, 77% male) with paroxysmal (68%) or persistent (32%) AF who underwent RFCA and 500 age, gender-matched controls were genotyped for the eNOS3 single nucleotide polymorphism (rs1799983). AF recurrence was monitored according to 2012 ACC/AHA/ESC guidelines. RESULTS: The frequencies of the rs1799983 variant alleles (T) in the case and control group were not significantly different (OR 1.05, 95% CI 0.75-1.46, p=0.798). AF patients with rs1799983 variants were more likely to have coronary artery disease or stroke than those without genetic variant at this gene (31.0% vs. 17.3%, p=0.004). During mean 17 months follow-up, early recurrence of AF (ERAF; within 3 months) and clinical recurrence (CR) of AF were 31.8% and 24.8%, respectively. The rs1799983 variant was associated with higher risk of ERAF (OR 1.71, 95% CI 1.06-2.79, p=0.028), but not with CR. ERAF occurred earlier (11+/-16 days) in variant group than those without variant allele (20+/-25 days, p=0.016). A multiple logistic regression analysis showed that presence of the rs1799983 variant (OR 1.75, 95% CI 1.07-2.86, p=0.026) and persistent AF were independent predictors for ERAF after AF ablation. CONCLUSION: The rs1799983 variant of the eNOS3 gene was associated with ERAF, but not with CR, after RFCA. eNOS3 gene variants may have a potential role for stratification of post-ablation management.

PITX2C loss-of-function mutations responsible for idiopathic atrial fibrillation

OBJECTIVE: This study aimed to identify novel PITX2c mutations responsible for idiopathic atrial fibrillation. METHODS: A cohort of 210 unrelated patients with idiopathic atrial fibrillation and 200 unrelated, ethnically matched healthy individuals used as controls were recruited. The whole coding exons and splice junctions of the PITX2c gene, which encodes a paired-like homeobox transcription factor required for normal cardiovascular morphogenesis, were sequenced in 210 patients and 200 control subjects. The causative potentials of the identified mutations were automatically predicted by MutationTaster and PolyPhen-2. The functional characteristics of the PITX2c mutations were explored using a dual-luciferase reporter assay system. RESULTS: Two novel heterozygous PITX2c mutations (p.Q105L and p.R122C) were identified in 2 of the 210 unrelated patients with idiopathic atrial fibrillation. These missense mutations were absent in the 400 control chromosomes and were both predicted to be pathogenic. Multiple alignments of PITX2c protein sequences across various species showed that the altered amino acids were highly evolutionarily conserved. A functional analysis demonstrated that the mutant PITX2c proteins were both associated with significantly reduced transcriptional activity compared with their wild-type counterparts. CONCLUSION: The findings of this study associate PITX2c loss-of-function mutations with atrial fibrillation, supporting the hypothesis that dysfunctional PITX2c confers enhanced susceptibility to atrial fibrillation and suggesting potential implications for early prophylaxis and allele-specific therapy for this common arrhythmia. .

Angiotensin-converting enzyme gene 2350 G/A polymorphism and susceptibility to atrial fibrillation in Han Chinese patients with essential hypertension

OBJECTIVE: The angiotensin-converting enzyme gene is one of the most studied candidate genes related to atrial fibrillation. Among the polymorphisms of the angiotensin-converting enzyme gene, the 2350 G/A polymorphism (rs4343) is known to have the most significant effects on the plasma angiotensin-converting enzyme concentration. The aim of the present study was to investigate the association of the angiotensin-converting enzyme 2350 G/A polymorphism with atrial fibrillation in Han Chinese patients with essential hypertension. METHODS: A total of 169 hypertensive patients were eligible for this study. Patients with atrial fibrillation (n = 75) were allocated to the atrial fibrillation group, and 94 subjects without atrial fibrillation were allocated to the control group. The PCR-based restriction fragment length polymorphism technique was used to assess the genotype frequencies. RESULTS: The distributions of the angiotensin-converting enzyme 2350 G/A genotypes (GG, GA, and AA, respectively) were 40.43%, 41.49%, and 18.08% in the controls and 18.67%, 46.67%, and 34.66% in the atrial fibrillation subjects (p = 0.037). The frequency of the A allele in the atrial fibrillation group was significantly greater than in the control group (58.00% vs. 38.83%, p = 0.0007). Compared with the wild-type GG genotype, the GA and AA genotypes had an increased risk for atrial fibrillation. Additionally, atrial fibrillation patients with the AA genotype had greater left atrial dimensions than the patients with the GG or GA genotypes (p<0.01 and p<0.05, respectively). CONCLUSIONS: The results obtained in this study indicate that the angiotensin-converting enzyme 2350 G/A polymorphism is associated with atrial fibrillation and that the A allele shows an increased risk for atrial fibrillation in Han Chinese patients with essential hypertension. .

Prevalence and spectrum of Nkx2.5 mutations associated with idiopathic atrial fibrillation

OBJECTIVE: The aim of this study was to evaluate the prevalence and spectrum of Nkx2.5 mutations associated with idiopathic atrial fibrillation (AF). METHODS: A cohort of 136 unrelated patients with idiopathic atrial fibrillation and 200 unrelated, ethnically matched healthy controls were enrolled. The coding exons and splice junctions of the Nkx2.5 gene were sequenced in 136 atrial fibrillation patients, and the available relatives of mutation carriers and 200 controls were subsequently genotyped for the identified mutations. The functional characteristics of the mutated Nkx2.5 gene were analyzed using a dual-luciferase reporter assay system. RESULTS: Two novel heterozygous Nkx2.5 mutations (p.N19D and p.F186S) were identified in 2 of the 136 unrelated atrial fibrillation cases, with a mutational prevalence of approximately 1.47%. These missense mutations co-segregated with atrial fibrillation in the families and were absent in the 400 control chromosomes. Notably, 2 mutation carriers also had congenital atrial septal defects and atrioventricular block. Multiple alignments of the Nkx2.5 protein sequences across various species revealed that the altered amino acids were completely conserved evolutionarily. Functional analysis demonstrated that the mutant Nkx2.5 proteins were associated with significantly reduced transcriptional activity compared to their wild-type counterpart. CONCLUSION: These findings associate the Nkx2.5 loss-of-function mutation with atrial fibrillation and atrioventricular block and provide novel insights into the molecular mechanism involved in the pathogenesis of atrial fibrillation. These results also have potential implications for early prophylaxis and allele-specific therapy of this common arrhythmia. .

Novel GATA5 loss-of-function mutations underlie familial atrial fibrillation

OBJECTIVE: This study aimed to identify novel GATA5 mutations that underlie familial atrial fibrillation. METHODS: A total of 110 unrelated patients with familial atrial fibrillation and 200 unrelated, ethnically matched healthy controls were recruited. The entire coding region of the GATA5 gene was sequenced in 110 atrial fibrillation probands. The available relatives of the mutation carriers and 200 controls were subsequently genotyped for the identified mutations. The functional effect of the mutated GATA5 was characterized using a luciferase reporter assay system. RESULTS: Two novel heterozygous GATA5 mutations (p.Y138F and p.C210G) were identified in two of the 110 unrelated atrial fibrillation families. These missense mutations cosegregated with AF in the families and were absent in the 400 control chromosomes. A cross-species alignment of GATA5 protein sequence showed that the altered amino acids were completely conserved evolutionarily. A functional analysis revealed that the mutant GATA5 proteins were associated with significantly decreased transcriptional activation when compared with their wild-type counterpart. CONCLUSION: The findings expand the spectrum of GATA5 mutations linked to AF and provide novel insights into the molecular mechanism involved in the pathogenesis of atrial fibrillation, suggesting potential implications for the early prophylaxis and personalized treatment of this common arrhythmia.

Polimorfismos beta1-adrenérgico associados com Fibrilação Atrial na Insuficiência Cardíaca Sistólica / Beta1-adrenergic receptor polymorphisms associated with atrial fibrillation in systolic heart failure

FUNDAMENTO: O sistema nervoso simpático apresenta grande importância na patogênese da fibrilação atrial na insuficiência cardíaca sistólica. A identificação de polimorfismos no gene ADBR1 do receptor beta1-adrenérgico representa um importante passo no conhecimento dessa patogênese. OBJETIVO: Este estudo analisou a associação entre os dois polimorfismos funcionais do gene ADBR1 do receptor beta1-adrenérgico, Ser49Gly e Arg389Gly, e a presença da fibrilação atrial em pacientes com insuficiência cardíaca sistólica. MÉTODOS: Estudo caso-controle com 144 pacientes portadores de insuficiência cardíaca sistólica, dos quais 24 com fibrilação atrial (casos) e 120 sem fibrilação atrial (controles). O DNA genômico foi extraído de leucócitos do sangue periférico e os genótipos dos polimorfismos Ser49Gly e Arg389Gly foram identificados em todos os indivíduos por PCR/RFLP (polymerase chain reaction / restriction fragment length polymorphism). RESULTADOS: A média etária foi 59 ± 13 anos, 70% dos pacientes eram do sexo masculino, 42% apresentavam causa isquêmica e 74% apresentavam hipertensão arterial sistêmica. Os genótipos Ser49Ser e Arg389Arg apresentaram associação significativa com fibrilação atrial (p = 0,005 e p = 0,01; respectivamente). Por meio de regressão logística, ambos ajustados para o tamanho do átrio esquerdo e idade, mantiveram associação significativa (Arg389Arg - odds ratios: 2,78; intervalo de confiança de 95% = 1,02 - 7,56 e Ser49Ser - odds ratios: 8,02; intervalo de confiança de 95% = 1,02 - 63,82). CONCLUSÃO: Ambos os genótipos associaram-se com fibrilação atrial nos pacientes estudados, porém apenas o polimorfismo Ser49Gly apresentava-se em equilíbrio de Hardy-Weinberg.

BACKGROUND: The sympathetic nervous system is of great importance in the pathogenesis of atrial fibrillation in systolic heart failure. The identification of polymorphisms in the beta1-adrenergic receptor gene (ADBR1) represents an important step in understanding this pathogenesis. OBJECTIVE: This study assessed the association between the two functional polymorphisms of the beta1-adrenergic receptor gene (ADBR1), Ser49Gly and Arg389Gly, and the presence of atrial fibrillation in patients with systolic heart failure. METHODS: Case-control study with 144 patients with systolic heart failure, including 24 with atrial fibrillation (cases) and 120 without atrial fibrillation (controls). Genomic DNA was extracted from peripheral blood leukocytes and the genotypes of Ser49Gly and Arg389Gly polymorphisms were identified in all individuals by PCR/RFLP (polymerase chain reaction / restriction fragment length polymorphism). RESULTS: Mean age was 59 ± 13 years, 70% of patients were males, 42% had ischemic causes and 74% had hypertension. Genotypes Ser49Ser and Arg389Arg were significantly associated with atrial fibrillation (p = 0.005 and p = 0.01, respectively). After logistic regression, both adjusted for left atrial size and age, the significant association persisted (Arg389Arg - odds ratios: 2.78, 95% confidence interval = 1.02 to 7.56 and Ser49Ser - odds ratios: 8.02, 95% confidence interval = 1.02 to 63.82). CONCLUSION: Both genotypes were associated with atrial fibrillation in patients; however, only Ser49Gly polymorphism was is in Hardy-Weinberg equilibrium.

Epidemiología, patogénesis y genética de la fibrilación auricular / Epidemiology, pathogenesis and genetics of atrial fibrillation

Desde hace cientos de años la Fibrilación Auricular ha levantado gran interés entre los investigadores tanto por su forma de presentación como por las graves consecuencias que ésta conlleva. Actualmente se ha constituido en uno de los principales rubros económicos en lo que a gastos en salud se refiere. Su etiología es multifactorial y afecta a millones de personas en todo el mundo, haciendo de esta patología un blanco muy importante de investigación en pos de lograr evitar el desarrollo de esta enfermedad. El objetivo de este estudio fue definir la epidemiología y patogénesis, así como realizar un abordaje relacionado a los factores genéticos relacionados con la fibrilación auricular. La revisión bibliográfica incluyó artículos originales y artículos de revisión seleccionados de la base de datos Medline teniendo como criterio de inclusión su publicación dentro de los últimos diez años.

For hundreds of years Atrial Fibrillation has raised great interest among researchers because of its presentation and the serious consequences that this entails. It has now become a main economic concern insofar as health expenditures are concerned. Its multifactorial etiology and its relationship to potentially preventable causes that affect millions of people around the world make this disease a very important target of investigation especially in its prevention. The aim of this paper is to define epidemiology, pathogenesis, and genetic factors related to atrial fibrillation. Review of literature included original articles and review articles selected from the MEDLINE database. Inclusion criterion was publication within the past ten years.

Controle do ritmo ou da frequência? Análise crítica dos ensaios recentes / Rhythm or rate control? Critical analysis of recent trials

Os estudos randomizados PIAF, STAF, RACE e AFFIRM demonstraram que o controle do ritmo, em relação ao controle da frequência cardíaca, não reduz a mortalidade e o risco de acidentes vasculares cerebrais em pacientes com fibrilação atrial e idade superior a 65 anos. Além disso, o estudo AF-CHF ampliou essa estratégia para os pacientes com insuficiência cardíaca. Como consequência, ambas as estratégias podem ser consideradas como abordagem primária no tratamento de pacientes com fibrilação atrial. No entanto, a subanálise de seguimento do AFFIRM demonstrou que o ritmo sinusal é benéfico, sugerindo que o problema é relacionado aos efeitos colaterais das drogas antiarrítmicas disponíveis. Portanto, o desenvolvimento de novas drogas (dronedarona) e de técnicas não-farmacológicas (ablação por cateter e por cirurgia minimamente invasiva) ganhou importância. Estudos comparativos entre as drogas antiarrítmicas e a ablação demonstraram superioridade da ablação para a manutenção do ritmo sinusal. O estudo PABA-CHF conbinou qualidade de vida, fração de ejeção e capacidade de exercício...

PIAF, STAF, RACE and AFFIRM randomized trials have shown that rhythm control, compared to heart rate control does not reduce the mortality and risk of stroke in patients with atrial fibrillation over 65 years of age. Furthermore, the AF-CHF study has expanded this strategy for patients with heart failure. As a result, both strategies may be considered as a primary approach in the treatment of patients with atrial fibrillation. However, the AFFIRM follow-up subanalysis showed that sinus rhythm is beneficial, suggesting the problem is related to the side effects of the available antiarrhythmic drugs. Therefore, the development of new drugs (dronedarone) and non-pharmacological techniques (catheter ablation, minimally invasive surgery) has gained importance. Comparative studies of antiarrhythmic drugs and ablation demonstrated a superiority of ablation in maintaining sinus rhythm. The PABA-CHF study combined quality of life with improved ejection fraction and exercise capacity as a primary outcome and concluded that ablation was superior to heart rate control (atrioventricular node ablation + biventricular pacemaker) suggesting ablation may be an option in selected patients with atrial fibrillation and heart failure. This article reviews recently published clinical trials on these topics and discusses their clinical implications.

Gene expression profiling of oxidative stress on atrial fibrillation in humans

Atrial Fibrillation (AF) is thought be caused by oxidative stress. Oxidative stress at the cellular level results from many factors, including exposure to alcohol, medications, cold, toxins or radiation. In this study we investigated gene transcriptional profiles on the human myocardial tissues from AF and oxidative stress conditions. Right atrial appendages were obtained from AF patients (n = 26) undergoing the Maze procedure, and from control patients (n = 26) who were in normal sinus rhythm and undergoing coronary artery bypass graft operation. To examine the effects of oxidative stress on AF, we used radioactive complementary DNA (cDNA) microarrays to evaluate changes in the expression of 1,152 known genes. This technology, which monitors thousands of genes simultaneously, gives us a better picture of the interactions between AF and oxidative stress. Total RNAs prepared from the retrieved tissues were used to synthesize(33)P-labeled cDNAs by reverse transcription and hybridized to cDNA microarrays. Gene expression profiles showed that 30 genes were upregulated and 25 were downregulated in AF patients compared with control patients. Moreover, comparison rank analysis revealed that the expression of five genes related to reactive oxygen species (ROS)-including flavin containing monooxygenase 1, monoamine oxidase B, ubiquitin specific protease 8, tyrosinase-related protein 1, and tyrosine 3-monooxygenase-increased by more than 2.0 of the Z-ratio, and two genes related to anti-oxidants including glutathione peroxidase 1, and heme oxygenase 2-decreased to the Z-ratio levels of <= -2.0. Apparently, a balanced regulation of pro- and anti-oxidation can be shifted toward pro-oxidation and can result in serious damage similar to that of human AF. Western blotting analysis confirmed the upregulation of tyrosinase-related protein 1 and tyrosine 3-monooxygenase and the downregulation of heme oxygenase 2. These results suggested that the gene expression pattern of myocardial tissues in AF patients can be associated with oxidative stress, resulting in a significant increase in ROS. Thus, the cDNA microarray technique was useful for investigating transcription profiles in AF. It showed that the intracellular mechanism of oxidative stress plays a pivotal role in the pathologic progression of AF and offers novel insight into potential treatment with antioxidants.