Effects of cardiac resynchronization therapy in patients with advanced congestive heart failure evaluated by real-time 3-dimensional echocardiography / 中华心血管病杂志

<p><b>OBJECTIVE</b>To quantitatively assess the effects of cardiac resynchronization therapy (CRT) in patients with advanced congestive heart failure by real-time 3-dimensional(3D) echocardiography (RT-3DE).</p><p><b>METHODS</b>Eighteen patients with advanced congestive heart failure underwent CRT with New York Heart association(NYHA) class III and IV and wide QRS complex (>120 ms) were included (17 dilated cardiomyopathy and 1 ischemic cardiomyopathy). Before CRT and 8 months after CRT, the clinical and RT-3DE parameters and outcome were analyzed.</p><p><b>RESULTS</b>The biventricular pacemaker was successfully implanted in 17 patients (94.4%). Compared with before CRT, NYHA class of patients decreased by 1.5 class (P < 0.01), left ventricular ejection fraction increased by 25% (P < 0.01), left ventricular end systolic volume decreased by 38% (P < 0.01), left ventricular systolic dyssynchrony index (SDI) improved significantly (14.2% before CRT vs. 9.8% after CRT, P < 0.01 ) post CRT. Change in SDI and change in LVEF was positively correlated (r = 0.62, P < 0.01) . The procedure complications and outcome during and after CRT included coronary sinus dissection (n = 1), left ventricular lead dislodgement (n = 1), phrenic nerve stimulation (n = 1), sudden cardiac death (n = 1). Three non-response patients were complicated with atrial fibrillation, nonspecific intraventricular block and dilated cardiomyopathy with postero-lateral scar tissue.</p><p><b>CONCLUSIONS</b>CRT could improve the cardiac function, correct the mechanical desynchronization and reverse left ventricular remodeling in patients with congestive heart failure, and SDI quantification by RT-3DE could predict increase of LVEF after CRT, however, there were complications related to the implantation procedure and possibilities of non-response.</p>

Eukaryotic expression vector pcDNA3-HERG transfection inhibits angiotensin II induced neonatal rabbit ventricular myocyte hypertrophy in vitro / 中华心血管病杂志

<p><b>OBJECTIVE</b>To explore the effects of eukaryotic expression vector pcDNA3-HERG transfection on angiotensin II (Ang II) induced myocyte hypertrophy in cultured neonatal rabbit ventricular myocytes.</p><p><b>METHODS</b>Neonatal rabbit ventricular myocytes and eukaryotic expression vector pcDNA3-HERG transfected ventricular myocytes were cultured in Dulbecco's-modified Eagle medium (DMEM), containing 1% fetal bovine serum (FBS) for 6 h, then stimulated with Ang II (10(-7) mol/L) for 48 h. Control ventricular myocytes were cultured in Dulbecco's-modified Eagle medium (DMEM), containing 1% fetal bovine serum (FBS) for 54 h. At 6 and 54 h, myocyte hypertrophic parameters including myocyte volume, total protein content and membrane capacitance, action potential duration (APD) and Calcineurin (CaN) activity were measured.</p><p><b>RESULTS</b>Compared to control myocytes, APD at 90% repolarization (APD(90)) was prolonged by 19.8% (P < 0.01), without signs of myocyte hypertrophy at 6 h post Ang II stimulation, APD(90) was prolonged by 22.1% (P < 0.01), myocyte volume, total protein content and membrane capacitance and CaN activity were significantly increased by 40.4%, 40.4%, 38.2% and 114.7% respectively (all P < 0.01) at 48 h after Ang II stimulation. HERG gene transfection upregulated I(HERG) tail current (3.6-fold higher than I(Kr)-rapidly activating delayed rectifier potassium current, P < 0.01). HERG gene transfection also accelerated and repolarization and a shortened APD(90) and inhibited myocyte hypertrophy and CaN activation induced by Ang II.</p><p><b>CONCLUSIONS</b>Ang II induced prolongation of APD(90) is directly associated with myocyte hypertrophy by increasing the Ca(2+) influx and resulting in the increment of intracellular Ca(2+) and activation of CaN reaction pathway.</p>

Dynamic changes of electrical remodeling in midmyocardium of rabbit left ventricle during the early stage of chronic pressure-overload / 生理学报

In the previous study, we had found that the action potential duration (APD) of midmyocardial (M) cells was gradually prolonged and M cells were easier to produce early after-depolarization (EAD) in the rabbit left ventricle during the early stage of chronic pressure-overload. The present study was performed to investigate the dynamic changes and significance of ionic current remodeling in M cells of rabbit left ventricle during the early stage of chronic pressure-overload. Sixty-four New Zealand rabbits were randomly divided into constriction groups and sham groups. The rabbit models with chronic pressure-overload were prepared by partial constriction of suprarenal abdominal aorta at the site proximal 5-10 mm away from the left renal artery. At 2 and 8 weeks after operation, the single cardiomyocytes were isolated by enzymatic digestion method. The midmyocardium from the anterolateral free wall of left ventricle was obtained by removing the epicardial and endocardial surfaces. Whole-cell patch-clamp technique was used to record the slowly activating delayed rectifier potassium current (I(Ks)), transient outward potassium current (I(to)), L-type calcium current (I(Ca-L)) of M cells. At 2 weeks after the constriction operation, compared with the sham group, I(Ks) tail current (I(Ks,tail)) and I(to) densities of M cells from constriction group significantly decreased by 33.3% and 51.5%, respectively. There was no significant difference in I(Ca-L) density between the two groups. At 8 weeks after operation, compared with the sham group, I(Ks,tail) and I(to) densities of M cells from constriction group significantly decreased by 37.0% and 49.2%, respectively. There was still no significant difference in I(Ca-L) density between the two groups. These results suggest that during the early phase of chronic pressure-overload, the electrical remodeling of M cells in rabbit left ventricle has developed, representing as the down regulations of I(Ks) and I(to) that can lead to the prolongation of APD, which might be a risk factor for the occurrence of malignant arrhythmia.

Functional expression of congenital long QT syndrome related HERG mutation A561V in vitro / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the functional expression of HERG mutation A561V detected in a Chinese congenital long QT syndrome family.</p><p><b>METHODS</b>The mutation gene A561V was cloned into eukaryotic expressive vector pcDNA3 by quick site-directed mutagenesis PCR and restriction enzymes. The wild-type HERG, heterozygous type HERG and HERG mutation A561V were respectively cotransfected with pRK5-GFP into HEK293 cells by Suprefact transfection regent. The protein expression was measured by immunofluorescence method and Western blot. The electrophysiological characteristics of transfected cells were determined by whole cell patch-clamp technique.</p><p><b>RESULTS</b>Direct sequence analyses revealed a C to T transition at position 1682. A561V mutation was correctly combined to eukaryotic expressive vector pcDNA3 and expressed in HEK293 cells. The protein expression of mutation and heterozygosis were located in cytoplasm and cellular membrane. 155 kDa and 135 kDa protein bands were detected in wild type HERG channel while only 135 kDa protein band was shown in heterozygous and mutational channels. Significant HERG tail-current was recorded in wild type HERG channel but not in mutation and heterozygosis channels.</p><p><b>CONCLUSION</b>This study evidenced a functional dominant-negative current suppression in HEK293 cells transfected with HERG mutation A561V.</p>

Construction of eukaryotic expression vector of congenital long QT syndrome related HERG gene A561V mutation and its expression in HEK293 cells / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the protocol of the construction of HERG gene mutations, an A561V mutation which was detected in a Chinese congenital long QT syndrome (LQTS) family had been constructed and expressed in vitro.</p><p><b>METHODS</b>The A561V cloning vector PGEM-HERG-A561V was constructed by quick site-directed mutagenesis PCR. The A561V expressive vector pcDNA3-HERG-A561V was constructed by restriction enzymes. pRK5-GFP was cotransfected with pcDNA3-HERG-A561V or wild type pcDNA3-HERG into HEK293 cells by Superfect transfection reagent. The protein was measured by immunofluorescence.</p><p><b>RESULTS</b>Direct sequence analyses revealed a C to T transition at position 1682. The A561V mutation was correctly combined to eukaryotic expressive vector pcDNA3 and expressed in HEK293 cells. The protein of mutation was expressed in cytoplasm and cellular membrane while the wild type gene was expressed only on cellular membrane.</p><p><b>CONCLUSION</b>The protocol can be used successfully to construct and express HERG A561V mutation and it forms the basement of the further study on functions of mutation.</p>

Association of the polymorphism of platelet membrane glycoprotein I a gene with myocardial infarction / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>Platelet membrane glycoprotein (GP) Ia/IIa complex is the major collagen receptor on platelets. Platelet activation by GP Ia/ IIa dependent adhesion leads to cellular events that catalyze prothrombin conversion and fibrin clot formation. Correlation between the polymorphism of platelet membrane GP Ia gene and myocardial infarction (MI) was explored.</p><p><b>METHODS</b>A total of 137 patient s with myocardial infarction and 175 controls with no history of coronary heart disease, thrombogenic and hemorrhagenic diseases were studied by case-control. Platelet GP I a gene 807 C/T polymorphisms were checked by polymerase chain reaction-sequence specific primers.</p><p><b>RESULTS</b>There were significant differences in the distribution of T and C alleles between MI and control groups (T:42.70% vs 32.00%, C:57.30% vs 68.00%, P<0.001). No matter among all subjects or among subjects aged <or= 60 years, the prevalence of genotypes (TT+TC) in MI group was significantly higher than that in control group [in all subjects; 69.34% vs 51.43%, P<0.005, odds ratio(OR)=2.14, 95% CI: 1.34-3.41; in subjects aged <or= 60 years; 75.90% vs 51. 52%, P<0.005, OR=2.96,95% CI 1.58-5.55]. Platelet GP Ia T allele was significantly associated with MI by multiple logistic regression (OR=4.96, 95% CI:2.55-10.90).</p><p><b>CONCLUSION</b>The above data suggest that there is a strong association between the presence of GP Ia T allele and MI. T allele ca n be a marker of genetic susceptibility to MI. These need to be substantiated by a large scale and prospective study.</p>