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Background/purpose: This study sought to elucidate the mechanism by which losartan inhibits blood pressure (BP) elevation in spontaneously hypertensive rats (SHRs)., Methods: Four-week-old Wistar-Kyoto (WKY) rats and SHRs were either treated with losartan (20 mg/kg/day) for 8 weeks or served as untreated controls. BP was measured by the tail-cuff method. At 12 weeks, isometric contraction of the aortic rings of the rats was evaluated with a force transducer and recorder. The mRNA and protein levels of the target Rho guanine nucleotide exchange factors (RhoGEFs), and the extent of myosin phosphatase target subunit 1 (MYPT-1) phosphorylation in the aorta, were determined using quantitative real-time polymerase chain reaction (qPCR) assay and Western blot analysis., Results: The BP of the four-week-old SHRs did not differ from that of the age-matched WKY rats, whereas the BP of the twelve-week-old control group SHRs was higher than that of the control group WKY rats. Losartan treatment, however, inhibited BP elevation in both rat strains, doing so to a greater extent in the treatment group SHRs. The contractile force in response to angiotensin II of the aortic rings from the SHRs treated with losartan was significantly lower than that of the aortic rings from the non-treated SHRs. The protein expression of leukemia-associated RhoGEF (LARG) was significantly higher in the non-treated SHRs compared to the non-treated WKY rats., Conclusion: The study results showed that the reduction of BP elevation by losartan in SHRs occurs through the suppression of LARG expression and MYPT-1 phosphorylation in vascular smooth muscle cells., (Copyright © 2019. Published by Elsevier B.V.)

Background/purpose: Brugada syndrome (BrS) is a hereditable sudden cardiac death (SCD). Mutations in the SCN5A gene (the most common BrS-causing gene) are responsible for 20-25% of this disease in Caucasian populations. However, the prevalence of SCN5A mutations in patients with BrS in the Chinese Han population in Taiwan remains unknown. Therefore, in this study, we investigated the prevalence of the SCN5A mutation in the largest BrS cohort in Taiwan., Methods: We consecutively enrolled 47 unrelated patients with BrS from medical centers and hospitals in Taiwan between 2000 and 2010. Mutations within all the 27 translated exons, and exon-intron boundaries of the SCN5A-encoded cardiac sodium channel were screened in all patients with BrS using direct sequencing. A total of 500 unrelated healthy volunteers with a normal electrocardiogram were genotyped as a control group., Results: SCN5A genetic variants were identified in 14 of the 47 patients with BrS and four of the 14 patients with BrS had missense mutations (1651 G>A, 1776 C>G, 3578 G>A). The prevalence rate of SCN5A mutations was approximately 8% (4/47), which was significantly lower than that reported in Caucasian populations (20-25%; p = 0.0007). The average age of these 14 BrS patients with SCN5A variants at diagnosis (12 men and 2 women) was 40 ± 13 years. Four patients experienced SCD, and six presented with seizure or syncope. Only three patients (3/14, 21.4%) had a family history of SCD., Conclusion: The prevalence of SCN5A mutations in the Chinese Han population in Taiwan may be lower than that reported in the Caucasian populations. In addition, most patients with BrS did not have a family history of SCD., (Copyright © 2013. Published by Elsevier B.V.)

Background/purpose: People receive electrocardiogram (ECG) examination for various reasons in a hospital setting. An important clinical practice issue may be that cardiologists need to be consulted for Brugada-type ECGs identified through routine screening. We investigated the prevalence and prognosis of patients with Brugada-type ECG in a hospital-based population in an attempt to improve the management of these patients., Methods: In 20,562 patients seeking medical care for non-cardiovascular reasons, 74,955 ECGs were performed from December 1999 to February 2001. The diagnostic criteria for Brugada-like ECG from the European Society of Cardiology were used. International Statistical Classification of Diseases codes and city residents' records were documented to indicate the reasons for visiting clinics or hospitalization and mortality outcome. Medical records were reviewed and telephone interviews were conducted., Results: Twenty-six (0.13%) of the 20,562 patients were confirmed to have Brugada-type ECGs. None of these patients had ever experienced syncope, near syncope or sudden cardiac death. After 57.1 ± 15.8 months of follow-up, there were four deaths out of the 26 patients with Brugada-type ECG (15.4%, 95% CI: 1.53-2.9%) compared with 2899 of those without (14.1%, 95% CI: 13.6-14.5%; p=0.89, log-rank test). Neither sudden cardiac death (p=0.61) nor hospitalized death (p=0.55) was different between patients with and without Brugada-type ECG., Conclusion: Patients with Brugada-type ECGs are not rare in a hospital-based population. The presence of Brugada-type ECGs in patients without syncope or sudden cardiac death was not associated with hospitalized mortality., (Copyright © 2011 Formosan Medical Association & Elsevier. Published by Elsevier B.V. All rights reserved.)

Background/purpose: Desmosome gene mutations have been reported in patients with arrhythmogenic right ventricular dysplasia (ARVD). However, there are hardly any genetic studies in Asians. We studied the clinical characteristics, cardiac manifestations and desmosome gene mutations in ARVD patients in Taiwan., Methods: Medical records of five ARVD patients were reviewed and genomic DNA was obtained from peripheral blood samples. Mutation screening in desmoplakin (DSP), plakophilin-2, desmoglein-2 (DSG2) and desmocollin-2 genes was performed using polymerase chain reaction and DNA sequencing techniques., Results: Among the five patients, three presented with palpitations followed by loss of consciousness, and the other two had palpitations or chest tightness without loss of consciousness. Electrocardiogram (ECG), magnetic resonance imaging and signal averaged ECG results were similar to those reported in Western countries. Mutations in the desmosome genes were identified in four of the five patients (three with a DSG2 mutation and one with a DSP mutation). Five gene mutations were noted in four patients and all mutations were novel (one patient had a DSG2 double mutation). The mutation types were missense in four and splicing mutation in one., Conclusion: Patients with ARVD in Taiwan had similar clinical and cardiac manifestations as reported in the Western literature. More than half of the patients had desmosome gene mutations.