Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 14 de 14
Filtrar
Más filtros

Bases de datos
País/Región como asunto
Tipo del documento
País de afiliación
Intervalo de año de publicación
1.
Circ J ; 84(9): 1528-1535, 2020 08 25.
Artículo en Inglés | MEDLINE | ID: mdl-32713877

RESUMEN

BACKGROUND: In Japan, the long-term care insurance (LTCI) system has an important role in helping elderly people, but there have been no clinical studies that have examined the relationship between the LTCI and prognosis for patients with acute heart failure (HF).Methods and Results:This registry was a prospective multicenter cohort, 1,253 patients were enrolled and 965 patients with acute HF aged ≥65 years were comprised the study group. The composite endpoint included all-cause death and hospitalization for HF after discharge. We divided the patients into 4 groups: (i) patients without LTCI, (ii) patients requiring support level 1 or 2, (iii) patients with care level 1 or 2, and (iv) patients with care levels 3-5. The Kaplan-Meier analysis identified a lower rate of the composite endpoint in group (i) than in the other groups. After adjusting for potentially confounding effects using a Cox proportional regression model, the hazard ratio (HR) of the composite endpoint increased significantly in groups (iii) and (iv) (adjusted HR, 1.62; 95% confidence interval [CI], 1.22-1.98 and adjusted HR, 1.62; 95% CI, 1.23-2.14, respectively) when compared with group (i). However, there was no significant difference between groups (i) and (ii). CONCLUSIONS: The level of LTCI was associated with a higher risk of the composite endpoint after discharge in acute HF patients.


Asunto(s)
Insuficiencia Cardíaca/economía , Insuficiencia Cardíaca/epidemiología , Seguro de Cuidados a Largo Plazo , Sistema de Registros , Enfermedad Aguda/economía , Enfermedad Aguda/epidemiología , Anciano , Anciano de 80 o más Años , Femenino , Estudios de Seguimiento , Insuficiencia Cardíaca/mortalidad , Humanos , Japón/epidemiología , Estimación de Kaplan-Meier , Masculino , Alta del Paciente , Readmisión del Paciente , Pronóstico , Modelos de Riesgos Proporcionales , Estudios Prospectivos , Factores de Riesgo , Resultado del Tratamiento
2.
Circ J ; 81(1): 69-76, 2016 Dec 22.
Artículo en Inglés | MEDLINE | ID: mdl-27904019

RESUMEN

BACKGROUND: Social background is important in preventing admission/readmission of heart failure (HF) patients. However, few clinical studies have been conducted to assess the social background of these patients, especially elderly patients.Methods and Results:The Kitakawachi Clinical Background and Outcome of Heart Failure (KICKOFF) Registry is a prospective multicenter community-based cohort of HF patients, established in April 2015. We compared the clinical characteristics and social background of the super-elderly group (≥85 years old) and the non-super-elderly group (<85 years old). This study included 647 patients; 11.8% of the super-elderly patients were living alone, 15.6% were living with only a partner, and of these, only 66.7% had the support of other family members. The super-elderly group had less control over their diet and drug therapies than the non-super-elderly group. Most patients in the super-elderly group were registered for long-term care insurance (77.4%); 73.5% of the super-elderly patients could walk independently before admission, but only 55.5% could walk independently at discharge, whereas 94% of the non-super-elderly patients could walk independently before admission and 89.4% could walk independently at discharge. CONCLUSIONS: The KICKOFF Registry provides unique detailed social background information of Japanese patients with HF. Super-elderly patients are at serious risk of social frailty; they need the support of other people and their ability to perform activities of daily living decline when hospitalized.


Asunto(s)
Anciano Frágil , Insuficiencia Cardíaca/epidemiología , Readmisión del Paciente , Sistema de Registros , Factores de Edad , Anciano , Anciano de 80 o más Años , Femenino , Insuficiencia Cardíaca/terapia , Humanos , Masculino , Persona de Mediana Edad , Factores Socioeconómicos
3.
BMJ Support Palliat Care ; 13(e3): e1300-e1307, 2024 Jan 08.
Artículo en Inglés | MEDLINE | ID: mdl-37169517

RESUMEN

OBJECTIVES: Morphine is effective in alleviating dyspnoea in patients with cancer. We aimed to investigate the effectiveness and safety of morphine administration for refractory dyspnoea in patients with advanced heart failure (HF). METHODS: We conducted a multicentre, prospective, observational study of hospitalised patients with advanced HF in whom morphine was administered for refractory dyspnoea. Morphine effectiveness was evaluated by dyspnoea intensity changes, assessed regularly by both a quantitative subjective scale (Visual Analogue Scale (VAS; graded from 0 to 100 mm)) and an objective scale (Support Team Assessment Schedule-Japanese (STAS-J; graded from 0 to 4 points)). Safety was assessed by vital sign changes and new-onset severe adverse events, including nausea, vomiting, constipation and delirium based on the Common Terminology Criteria for Adverse Events. RESULTS: From 15 Japanese institutions between September 2020 and August 2022, we included 28 hospitalised patients with advanced HF in whom morphine was administered (mean age: 83.8±8.7 years, male: 15 (54%), New York Heart Association class IV: 26 (93%) and mean left ventricular ejection fraction: 38%±19%). Both VAS and STAS-J significantly improved from baseline to day 1 (VAS: 67±26 to 50±31 mm; p=0.02 and STAS-J: 3.3±0.8 to 2.6±1.1 points; p=0.006, respectively), and thereafter the improvements sustained through to day 7. After morphine administration, vital signs including blood pressure, pulse rate and oxygen saturation did not change, and no new-onset severe adverse events occurred through to day 7. CONCLUSIONS: This study suggested acceptable effectiveness and safety for morphine administration in treating refractory dyspnoea in hospitalised patients with advanced HF.


Asunto(s)
Insuficiencia Cardíaca , Neoplasias , Anciano , Anciano de 80 o más Años , Humanos , Masculino , Disnea/etiología , Disnea/inducido químicamente , Insuficiencia Cardíaca/complicaciones , Insuficiencia Cardíaca/tratamiento farmacológico , Morfina/efectos adversos , Estudios Prospectivos , Femenino
4.
Circ Rep ; 3(4): 217-226, 2021 Mar 13.
Artículo en Inglés | MEDLINE | ID: mdl-33842727

RESUMEN

Background: This study investigated whether combination therapy (CT) with renin-angiotensin system inhibitors and ß-blockers improved endpoints in acute heart failure (AHF). Methods and Results: AHF patients were recruited to this prospective multicenter cohort study between April 2015 and August 2017. Patients were divided into 3 categories based on ejection fraction (EF), namely heart failure (HF) with reduced EF (HFrEF), HF with midrange EF (HFmrEF), and HF with preserved EF (HFpEF), and a further into 2 groups according to physical status (those who could walk independently outdoors and those who could not). The composite endpoint included all-cause mortality and hospitalization for HF. Data at the 1-year follow-up were available for 1,018 patients. The incidence of the composite endpoint was significantly lower in the CT than non-CT group for HFrEF patients, but not among HFmrEF and HFpEF patients. For patients who could walk independently outdoors, a significantly lower rate of the composite endpoint was recorded only in the HFrEF group. The differences were maintained even after adjustment for comorbidities and prescriptions, with hazard ratios (95% confidence intervals) of 0.39 (0.20-0.76) and 0.48 (0.22-0.99), respectively. Conclusions: In this study, CT was associated with the prevention of adverse outcomes in patients with HFrEF. Moreover, CT prevented adverse events only among patients without a physical disorder, not among those with a physical disorder.

5.
Clin Cardiol ; 44(6): 848-856, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33963771

RESUMEN

BACKGROUND: In Japan, both the prevalence of the elderly and super-elderly and those of acute heart failure (AHF) have been increasing rapidly. METHODS: This registry was a prospective multicenter cohort, which enrolled a total of 1253 patients with AHF. In this study, 1117 patients' follow-up data were available and were categorized into three groups according to age: <75 years old (nonelderly), 75-84 years old (elderly), and ≥ 85 years old (super-elderly). The endpoint was defined as all-cause death and each mode of death after discharge during the 3-years follow-up period. RESULTS: Based on the Kaplan-Meier analysis, a gradually increased risk of all-cause death according to age was found. Among the three groups, the proportion of HF death was of similar trend; however, the proportion of infection death was higher in elderly and super-elderly patients. After adjusting for potentially confounding effects using the Cox and Fine-Gray model, the hazard ratio (HR) of all-cause death increased significantly in elderly and super-elderly patients (HR, 2.60; 95% confidence interval [CI], 1.93-3.54 and HR, 5.04; 95% CI, 3.72-6.92, respectively), when compared with nonelderly patients. The highest sub-distribution HR in detailed mode of death was infection death in elderly and super-elderly patients (HR, 4.25; 95% CI, 1.75-10.33 and HR, 10.10; 95% CI, 3.78-27.03, respectively). CONCLUSIONS: In this population, the risk of all-cause death was found to increase in elderly and super-elderly. Elderly patients and especially super-elderly patients with AHF were at a higher risk for noncardiovascular death, especially infection death.


Asunto(s)
Insuficiencia Cardíaca , Enfermedad Aguda , Anciano , Humanos , Japón/epidemiología , Pronóstico , Modelos de Riesgos Proporcionales , Estudios Prospectivos , Sistema de Registros
6.
Geriatr Gerontol Int ; 20(10): 967-973, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-32815272

RESUMEN

AIM: In Japan, the long-term care insurance (LTCI) system is important for elderly people living at home; however, no clinical studies have revealed a relationship between home- or community-based services and outcomes in patients with acute heart failure (AHF). METHODS: This was a prospective multicenter cohort study of patients with AHF enrolled between April 2015 and August 2017. Patients aged ≥65 years with LTCI were divided into those receiving home- and community-based services (service users) and without home and community-based services (service non-users). The endpoint was defined as a composite endpoint, which included all-cause mortality and hospitalization for heart failure after discharge. Subgroup analyses were performed for elderly patients (<85 years) or super-elderly patients (≥85 years). RESULTS: The study participants were eligible for LTCI two times more than community-dwelling people were. At the 1-year follow-up period, the rate of the composite endpoint showed no significant difference between service users and service non-users among all patients or super-elderly patients. However, in elderly patients, the rate of the composite endpoint was significantly lower among service users than service non-users. The difference was independently maintained even after adjustments for differences in comorbidities or in social backgrounds (adjusted hazard ratio 0.62; 95% confidence interval 0.38-0.99, and adjusted hazard ratio 0.57; 95% confidence interval 0.35-0.90, respectively). CONCLUSIONS: In this study, adverse events following discharge of patients with AHF who used home- and community-based services were prevented only in elderly patients, not in super-elderly patients. Geriatr Gerontol Int 2020; 20: 967-973.


Asunto(s)
Insuficiencia Cardíaca/epidemiología , Servicios de Atención de Salud a Domicilio/estadística & datos numéricos , Hospitalización/estadística & datos numéricos , Seguro de Cuidados a Largo Plazo/estadística & datos numéricos , Factores de Edad , Anciano , Anciano de 80 o más Años , Estudios de Cohortes , Femenino , Anciano Frágil , Humanos , Japón/epidemiología , Cuidados a Largo Plazo , Masculino , Evaluación de Resultado en la Atención de Salud , Modelos de Riesgos Proporcionales , Estudios Prospectivos , Sistema de Registros
7.
J Cardiol ; 73(5): 343-350, 2019 05.
Artículo en Inglés | MEDLINE | ID: mdl-30591322

RESUMEN

BACKGROUND: KCNQ1-T587M is a C-terminal mutation correlated with severe phenotypes of long QT syndrome (LQTS). However, functional analysis of KCNQ1 channels with the T587M mutation showed a mild genotype in the form of haploinsufficiency in a heterologous expression system. This study sought to explore the molecular mechanism underlying the phenotype-genotype dissociation of LQTS patients carrying the KCNQ1-T587M mutation. METHODS: cDNAs for wild-type (WT) and KCNQ1 mutations (R259C and T587M) were transiently transfected into HEK293 cells stably expressing hERG (hERG-HEK), and whole-cell patch-clamp technique was performed to examine the effect of KCNQ1 mutations on IKr-like currents. In addition, fluorescence resonance energy transfer (FRET) was conducted to demonstrate the molecular interaction between KCNQ1 and hERG when co-expressed in HEK293 cells. RESULTS: KCNQ1-T587M mutation produced a significant (p<0.01) decrease in IKr-like tail current densities without affecting the gating kinetics, while KCNQ1-R259C mutation had no significant effect on the IKr-like tail current densities. Consistent with this result, FRET experiments demonstrated that both KCNQ1-WT and -R259C interacted with hERG in the cytosol and on the plasma membrane; however, the interaction between KCNQ1-T587M and hERG was observed only in the cytosol, and hERG proteins were seldom transported to the cell membrane, suggesting that the KCNQ1-T587M mutation impaired the trafficking of hERG to the cell membrane. CONCLUSIONS: The disruption of hERG trafficking caused by the KCNQ1-T587M mutation is likely the reason why some patients exhibit severe LQTS phenotypes.


Asunto(s)
Canales de Potasio Éter-A-Go-Go/fisiología , Canal de Potasio KCNQ1/genética , Síndrome de QT Prolongado/genética , Canales de Potasio Éter-A-Go-Go/genética , Células HEK293 , Humanos , Canal de Potasio KCNQ1/fisiología , Síndrome de QT Prolongado/fisiopatología , Mutación , Técnicas de Placa-Clamp , Fenotipo , Transporte de Proteínas , Transfección
8.
J Cardiol ; 73(6): 522-529, 2019 06.
Artículo en Inglés | MEDLINE | ID: mdl-30598389

RESUMEN

BACKGROUND: Although activities of daily living (ADL) are recognized as being pertinent in averting relevant readmission of heart failure (HF) and mortality, little research has been conducted to assess a correlation between a decline in ADL and outcomes in HF patients. METHODS: The Kitakawachi Clinical Background and Outcome of Heart Failure Registry is a prospective, multicenter, community-based cohort of HF patients. We categorized the patients into four types of ADL: independent outdoor walking, independent indoor walking, indoor walking with assistance, and abasia. We defined a decline in ADL (decline ADL) as downgrade of ADL and others (non-decline ADL) as preservation of ADL before discharge compared with admission. RESULTS: Among 1253 registered patients, 923 were eligible, comprising 98 (10.6%) with decline ADL and 825 (89.4%) with non-decline ADL. Decline ADL exhibited a higher risk of hospitalization for HF and mortality compared with non-decline ADL. A multivariate analysis revealed that decline ADL emerged as an independent risk factor of hospitalization for HF [hazard ratio (HR), 1.42; 95% confidence interval (CI): 1.01-1.96; p=0.046] and mortality (HR, 1.95; 95% CI: 1.23-2.99; p<0.01). Although 66.3% of patients with decline ADL were registered for long-term care insurance, few received daycare services (32.7%) or home-visit medical services (8.2%). CONCLUSIONS: Decline in ADL is a predictor of hospitalization for HF and mortality in HF patients.


Asunto(s)
Actividades Cotidianas , Insuficiencia Cardíaca/mortalidad , Hospitalización/estadística & datos numéricos , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Modelos de Riesgos Proporcionales , Estudios Prospectivos , Sistema de Registros , Factores de Riesgo , Caminata
9.
Circulation ; 107(6): 838-44, 2003 Feb 18.
Artículo en Inglés | MEDLINE | ID: mdl-12591753

RESUMEN

BACKGROUND: Experimental studies suggest that the interval between peak and end of T wave (Tpe) in transmural ECGs reflects transmural dispersion of repolarization (TDR), which is amplified by beta-adrenergic stimulation in the LQT1 model. In 82 patients with genetically identified long-QT syndrome (LQTS) and 33 control subjects, we examined T-wave morphology and various parameters for repolarization in 12-lead ECGs including corrected QT (QTc; QT/R-R(1/2)) and corrected Tpe (Tpec; Tpe/R-R(1/2)) before and during exercise stress tests. METHODS AND RESULTS: Under baseline conditions, LQT1 (n=51) showed 3 cardinal T-wave patterns (broad-based, normal-appearing, late-onset) and LQT2 (n=31) 3 patterns (broad-based, bifid with a small or large notch). The QTc and Tpec were 510+/-68 ms and 143+/-53 ms in LQT1 and 520+/-61 ms and 195+/-69 ms in LQT2, respectively, which were both significantly larger than those in control subjects (402+/-36 ms and 99+/-36 ms). Both QTc and Tpec were significantly prolonged during exercise in LQT1 (599+/-54 ms and 215+/-46 ms) with morphological change into a broad-based T-wave pattern. In contrast, exercise produced a prominent notch on the descending limb of the T wave, with no significant changes in the QTc and Tpec (502+/-82 ms and 163+/-86 ms: n=19) in LQT2. CONCLUSIONS: Tpe interval increases during exercise in LQT1 but not in LQT2, which may partially account for the finding that fatal cardiac events in LQT1 are more often associated with exercise.


Asunto(s)
Electrocardiografía , Prueba de Esfuerzo , Síndrome de QT Prolongado/diagnóstico , Síndrome de QT Prolongado/fisiopatología , Fenotipo , Adolescente , Adulto , Edad de Inicio , Niño , Análisis Mutacional de ADN , Femenino , Genotipo , Humanos , Masculino , Valor Predictivo de las Pruebas , Valores de Referencia
10.
J Am Coll Cardiol ; 44(1): 117-25, 2004 Jul 07.
Artículo en Inglés | MEDLINE | ID: mdl-15234419

RESUMEN

OBJECTIVES: We sought to compare the arrhythmic risk and sensitivity to sympathetic stimulation of mutations located in transmembrane regions and C-terminal regions of the KCNQ1 channel in the LQT1 form of congenital long QT syndrome (LQTS). BACKGROUND: The LQT1 syndrome is frequently manifested with variable expressivity and incomplete penetrance and is much more sensitive to sympathetic stimulation than the other forms. METHODS: Sixty-six LQT1 patients (27 families) with a total of 19 transmembrane mutations and 29 patients (10 families) with 8 C-terminal mutations were enrolled from five Japanese institutes. RESULTS: Patients with transmembrane mutations were more frequently affected based on electrocardiographic (ECG) diagnostic criteria (82% vs. 24%, p < 0.0001) and had more frequent LQTS-related cardiac events (all cardiac events: 55% vs. 21%, p = 0.002; syncope: 55% vs. 21%, p = 0.002; aborted cardiac arrest or unexpected sudden cardiac death: 15% vs. 0%, p = 0.03) than those with C-terminal mutations. Patients with transmembrane mutations had a greater risk of first cardiac events occurring at an earlier age, with a hazard ratio of 3.4 (p = 0.006) and with an 8% increase in risk per 10-ms increase in corrected Q-Tend. The baseline ECG parameters, including Q-Tend, Q-Tpeak, and Tpeak-end intervals, were significantly greater in patients with transmembrane mutations than in those with C-terminal mutations (p < 0.005). Moreover, the corrected Q-Tend and Tpeak-end were more prominently increased with exercise in patients with transmembrane mutations (p < 0.005). CONCLUSIONS: In this multicenter Japanese population, LQT1 patients with transmembrane mutations are at higher risk of congenital LQTS-related cardiac events and have greater sensitivity to sympathetic stimulation, as compared with patients with C-terminal mutations.


Asunto(s)
Síndrome de QT Prolongado/congénito , Síndrome de QT Prolongado/genética , Mutación Puntual/genética , Canales de Potasio con Entrada de Voltaje , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Arritmias Cardíacas/congénito , Arritmias Cardíacas/epidemiología , Arritmias Cardíacas/genética , Niño , Preescolar , Electrocardiografía , Técnicas Electrofisiológicas Cardíacas , Prueba de Esfuerzo , Salud de la Familia , Femenino , Predisposición Genética a la Enfermedad/epidemiología , Predisposición Genética a la Enfermedad/genética , Sistema de Conducción Cardíaco/patología , Humanos , Japón/epidemiología , Canales de Potasio KCNQ , Canal de Potasio KCNQ1 , Síndrome de QT Prolongado/epidemiología , Masculino , Persona de Mediana Edad , Análisis Multivariante , Canales de Potasio/genética , Modelos de Riesgos Proporcionales , Factores de Riesgo , Sensibilidad y Especificidad
11.
J Mol Cell Cardiol ; 42(3): 662-9, 2007 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-17292394

RESUMEN

Mutations in KCNQ1, the gene encoding the delayed rectifier K(+) channel in cardiac muscle, cause long QT syndrome (LQTS). We studied 3 families with LQTS, in whom a guanine to adenine change in the last base of exon 7 (c.1032G>A), previously reported as a common splice-site mutation, was identified. We performed quantitative measurements of exon-skipping KCNQ1 mRNAs caused by this mutation using real-time reverse transcription polymerase chain reaction. Compared with normal individuals who have minor fractions of splicing variants (Delta7-8: 0.1%, Delta8: 6.9%, of total KCNQ1 transcripts), the affected individuals showed remarkable increases of exon-skipping mRNAs (Delta7: 23.5%, Delta7-8: 16.8%, Delta8: 4.5%). Current recordings from Xenopus laevis oocytes heterologously expressing channels of wild-type (WT) or exon-skipping KCNQ1 (Delta7, Delta7-8, or Delta8) revealed that none of the mutants produced any measurable currents, and moreover they displayed mutant-specific degree of dominant-negative effects on WT currents, when co-expressed with WT. Confocal microscopy analysis showed that fluorescent protein-tagged WT was predominantly expressed on the plasma membrane, whereas the mutants showed intracellular distribution. When WT was co-expressed with mutants, the majority of WT co-localized with the mutants in the intracellular space. Finally, we provide evidence showing direct protein-protein interactions between WT and the mutants, by using fluorescence resonance energy transfer. Thus, the mutants may exert their dominant-negative effects by trapping WT intracellularly and thereby interfering its translocation to the plasma membrane. In conclusion, our data provide a mechanistic basis for the pathogenesis of LQTS caused by a splicing mutation in KCNQ1.


Asunto(s)
Canal de Potasio KCNQ1/genética , Canal de Potasio KCNQ1/metabolismo , Síndrome de QT Prolongado/metabolismo , Empalme del ARN/genética , Animales , Secuencia de Bases , Fenómenos Biofísicos , Biofisica , Células COS , Chlorocebus aethiops , Electrofisiología , Exones/genética , Síndrome de QT Prolongado/genética , Mutación/genética , Técnicas de Placa-Clamp , ARN Mensajero/genética , Xenopus laevis
12.
J Am Coll Cardiol ; 46(11): 2100-6, 2005 Dec 06.
Artículo en Inglés | MEDLINE | ID: mdl-16325048

RESUMEN

OBJECTIVES: We carried out a complete screening of the SCN5A gene in 38 Japanese patients with Brugada syndrome to investigate the genotype-phenotype relationship. BACKGROUND: The gene SCN5A encodes the pore-forming alpha-subunit of voltage-gated cardiac sodium (Na) channel, which plays an important role in heart excitation/contraction. Mutations of SCN5A have been identified in 15% of patients with Brugada syndrome. METHODS: In 38 unrelated patients with clinically diagnosed Brugada syndrome, we screened for SCN5A gene mutations using denaturing high-performance liquid chromatography and direct sequencing, and conducted a functional assay for identified mutations using whole-cell patch-clamp in heterologous expression system. RESULTS: Four heterozygous mutations were identified (T187I, D356N, K1578fs/52, and R1623X) in 4 of the 38 patients. All of them had bradyarrhythmic complications: three with sick sinus syndrome (SSS) and the other (D356N) with paroxysmal complete atrioventricular block. SCN5A-linked Brugada patients were associated with a higher incidence of bradyarrhythmia (4 of 4) than non-SCN5A-linked Brugada patients (2 of 34). Families with T187I and K1578fs/52 had widespread penetrance of SSS. Notably, the patient with K1578fs/52, who had been diagnosed as having familial SSS without any clinical signs of Brugada syndrome, showed a Brugada-type ST-segment elevation after intravenous administration of pilsicainide and programmed electrical stimulation-induced ventricular tachycardia. All of the mutations encoded non-functional Na channels, and thus were suggested to cause impulse propagation defect underlying bradyarrhythmias. CONCLUSIONS: Our findings suggest that loss-of-function SCN5A mutations resulting in Brugada syndrome are distinguished by profound bradyarrhythmias.


Asunto(s)
Bradicardia/complicaciones , Bradicardia/genética , Bloqueo de Rama/complicaciones , Bloqueo de Rama/genética , Canales de Sodio/genética , Adulto , Anciano , Pueblo Asiatico/genética , Cromatografía Líquida de Alta Presión , Codón sin Sentido , Análisis Mutacional de ADN , Femenino , Mutación del Sistema de Lectura , Humanos , Masculino , Persona de Mediana Edad , Mutagénesis Sitio-Dirigida , Canal de Sodio Activado por Voltaje NAV1.5 , Técnicas de Placa-Clamp , Síndrome
13.
J Cardiovasc Pharmacol ; 43(2): 178-82, 2004 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-14716203

RESUMEN

Whole-cell patch-clamp techniques were employed to examine the effects of bepridil, a Ca2+ channel blocker with Vaughan Williams class III action, on a slow component of cardiac delayed rectifier K+ current (IKs), which was reconstituted in HEK293 cells by transfecting KCNQ1 and KCNE1. Micromolar bepridil inhibited tail currents carried by KCNQ1/KCNE1 channels in a concentration-dependent manner (IC50 = 5.3 +/- 0.7 microM at -40 mV from 1000 milliseconds test pulse). When the effect of the drug was examined with a short test pulse protocol (250 milliseconds), IC50 became two-fold smaller than that measured with 1000 milliseconds test pulse (2.5 +/- 0.8 microM). The envelope-of-tails protocol was used to assess how the duration of depolarizing pulse affects the drug action on the outward KCNQ1/KCNE1 channel current. The drug significantly inhibited tail currents more potently during shorter pulses (<600 milliseconds). Bepridil's block was therefore time dependent, and its binding affinity to the channel was greater in the closed state channel, as evidenced by unblocking during prolonged depolarization. These properties of channel blockade appear to underscore the mechanism of bepridil's effect on IKs current.


Asunto(s)
Bepridil/farmacología , Bloqueadores de los Canales de Calcio/farmacología , Canales de Potasio con Entrada de Voltaje , Canales de Potasio/efectos de los fármacos , Células Cultivadas , Humanos , Canales de Potasio KCNQ , Canal de Potasio KCNQ1 , Técnicas de Placa-Clamp , Canales de Potasio/fisiología , Transfección
14.
J Cardiovasc Electrophysiol ; 15(2): 190-9, 2004 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-15028050

RESUMEN

INTRODUCTION: Beta-blockers are widely used to prevent the lethal cardiac events associated with the long QT syndrome (LQTS), especially in KCNQ1-related LQTS (LQT1) patients. Some LQT1 patients, however, are refractory to this therapy. METHODS AND RESULTS: Eighteen symptomatic LQTS patients (12 families) were genetically diagnosed as having heterozygous KCNQ1 variants and received beta-blocker therapy. Cardiac events recurred in 4 members (3 families) despite continued therapy during mean follow-up of 70 months. Three of these patients (2 families) had the same mutation [A341V (KCNQ1)]; and the other had R243H (KCNQ1). The latter patient took aprindine, which seemed to be responsible for the event. By functional assay using a heterologous mammalian expression system, we found that A341V (KCNQ1) is a loss-of-function type mutation (not dominant negative). Further genetic screening revealed that one A341V (KCNQ1) family cosegregated with S706C (KCNH2) and another with G144S (KCNJ2). Functional assay of the S706C (KCNH2) mutation was found to reduce the current density of expressed heterozygous KCNH2 channels with a positive shift (+8 mV) of the activation curve. Action potential simulation study was conducted based on the KYOTO model to estimate the influence of additional gene modifiers. In both models mimicking LQT1 plus 2 and LQT1 plus 7, the incidence of early afterdepolarization was increased compared with the LQT1 model under the setting of beta-adrenergic stimulation. CONCLUSION: Multiple mutations in different LQTS-related genes may modify clinical characteristics. Expanded gene survey may be required in LQT1 patients who are resistant to beta-blocker therapy.


Asunto(s)
Antagonistas Adrenérgicos beta/uso terapéutico , Variación Genética/efectos de los fármacos , Variación Genética/genética , Síndrome de QT Prolongado/tratamiento farmacológico , Síndrome de QT Prolongado/genética , Potenciales de Acción/efectos de los fármacos , Potenciales de Acción/genética , Adolescente , Adulto , Niño , Electrocardiografía , Salud de la Familia , Femenino , Estudios de Seguimiento , Predisposición Genética a la Enfermedad/genética , Humanos , Japón , Masculino , Persona de Mediana Edad , Mutación Missense/efectos de los fármacos , Mutación Missense/genética , Linaje , Fenotipo , Polimorfismo de Nucleótido Simple/efectos de los fármacos , Polimorfismo de Nucleótido Simple/genética , Canales de Potasio/efectos de los fármacos , Canales de Potasio/genética , Resultado del Tratamiento
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA