Level of Pregnancy-associated Plasma Protein-A Correlates With Coronary Thin-cap Fibroatheroma Burden in Patients With Coronary Artery Disease: Novel Findings From 3-Vessel Virtual Histology Intravascular Ultrasound Assessment.

Pregnancy-associated plasma protein-A (PAPP-A) level is an independent predictor of acute cardiovascular event occurrence. To test the hypothesis that increased PAPP-A levels would be associated with a higher burden of coronary thin-cap fibroatheroma (TCFA) thereby underlying the heightened risk for cardiovascular events in patients with coronary artery disease; 154 patients (462 vessels and 975 plaques) with stable angina or non-ST-segment elevation acute coronary syndrome (NSTE-ACS) referred for percutaneous coronary intervention were assessed using 3-vessel virtual histology (VH)-intravascular ultrasound (IVUS). Thin-cap fibroatheroma virtual histology was defined as focal, necrotic core (NC)-rich (≥10% of cross-sectional area) plaques in contact with the lumen, and plaque burden ≥40%. Pregnancy-associated plasma protein-A levels were determined by sandwich enzyme-linked immunosorbent assay, and patients were divided into 3 groups based on PAPP-A level tertiles. Although the highest PAPP-A level tertile was not associated with 3-vessel plaque number, it was associated with 3-vessel VH-TCFA number and necrotic core volume. Patients with ≥3 VH-TCFAs had a higher PAPP-A level than patients with 1 to 3 VH-TCFAs or without any VH-TCFA (13.3 ±â€Š11.8 versus 7.8 ±â€Š4.7 versus 7.4 ±â€Š4.7 mIU/L, P < 0.001, respectively). Moreover, PAPP-A level was an independent predictor of higher total number of VH-TCFAs (OR 1.18; 95% CI 1.07-1.29, P = 0.001). This VH-IVUS study demonstrated, for the first time to our knowledge, that higher PAPP-A levels are associated with higher 3-vessel TCFA burden in patients with coronary artery disease. Pregnancy-associated plasma protein-A, therefore, might be a useful serum biomarker to predict increased coronary TCFA burden and plaque instability.

Comprehensive assessment of the association of WNK4 polymorphisms with hypertension: evidence from a meta-analysis.

The relationship between with-no-lysine [K] kinase 4 (WNK4) gene polymorphisms and hypertension has been widely investigated, However, the studies yielded contradictory results. To evaluate these inconclusive findings comprehensively, we therefore performed a meta-analysis. Ten articles encompassing 16 independent case-control studies with 6089 hypertensive cases and 4881 normotensive controls were selected for this meta-analysis. Four WNK4 gene polymorphisms were identified (G1155942T, G1156666A, T1155547C, and C6749T). The results showed statistically significant associations of G1155942T polymorphism (allelic genetic model: odds ration or OR = 1.62, 95% confidence interval or CI: 1.11-2.38, P = 0.01; dominant model: OR = 1.85, 95% CI: 1.07-3.19, P = 0.03) and C6749T polymorphism (allele contrast: OR = 2.04, 95% CI: 1.60-2.59, P<0.01; dominant model: OR = 2.04, 95%CI: 1.59-2.62, P<0.01; and homozygous model: OR = 5.01, 95% CI: 1.29-19.54, P = 0.02) with hypertension risk. However, neither C1155547T nor G1156666A was associated significantly with hypertension susceptibility. In conclusion, this meta-analysis suggested that WNK4 G1155942T and C6749T gene polymorphisms may contribute to the susceptibility and development of hypertension. Further well-designed studies with larger sample size are required to elucidate the association of WNK4 gene multiple polymorphisms with hypertension risk.

[Study on the efficiency of the European System for Cardiac Operative Risk Evaluation (EuroSCORE) in predicting in-hospital mortality of the patients with percutaneous coronary intervention].

OBJECTIVE: To investigate the efficiency of European System for Cardiac Operative Risk Evaluation (EuroSCORE) in predicting in-hospital mortality for the patients after percutaneous coronary intervention (PCI). METHODS: Retrospective analysis was conducted on the patients who had undergone PCI in our hospital since year 2005 to 2007. We used both cumulative EuroSCORE score and logistic EuroSCORE to predict the in-hospital morality and to analyze the correlation between the predicted mortality and the actual mortality. RESULTS: According to the additive EuroSCORE, we divided the patients into three groups, the additive EuroSCORE 0-2 were divided into low-risk group, 3-5 were divided into mid-risk group and ≥ 6 into high-risk group. The actual in-hospital mortality rates were 0%, 0.47% and 6.09% respectively. The EuroSCORE model demonstrated an overall relation between the EuroSCORE ranking and the incidence of in-hospital mortality (P<0.001). Results from the multivariable logistic regression analysis showed that the EuroSCORE was an independent in-hospital mortality predictor (P<0.01). CONCLUSION: The EuroSCORE risk model and the in-hospital mortality were significantly correlated, indicating that the model was a promising method for predicting the in-hospital mortality of PCI patients.

[Interleukin-1beta upregulates matrix metalloproteinase-2 expression and activity in cardiac fibroblasts via nitric oxide synthase pathway].

OBJECTIVE: To investigate the effect of interleukin-1beta (IL-1beta) on expression and activity of matrix metalloproteinase-2 (MMP-2) of cultured human cardiac fibroblasts and related signaling pathway. METHODS: Primary human cardiac fibroblasts seeded in 6-well tissue culture plates and cultured to 80% to 90% confluence were harvested at passage 3 to 6 and exposed to IL-1beta at various concentrations for 24 h, culture supernatant and cell protein were obtained. MMP-2 mRNA was determined by RT-PCR. The activity of MMP-2 was analyzed by zymography and the expression of inducible nitric oxide synthase (iNOS) protein level was detected by Western blot analysis. Assessment of NO production in the culture supernatant was performed using the Griess method. RESULTS: IL-1beta (4 ng/ml) significantly increased MMP-2 activity of cultured fibroblasts in a time-dependent manner. MMP-2 mRNA expression was significantly upregulated by IL-1beta (4 ng/ml and 10 ng/ml, all P<0.01). Moreover, IL-1beta also significantly increased NO production in supernatant (P<0.01) and these effects could be significantly blocked by cotreatment with L-NMMA (10(-3) mol/L, all P<0.01). Western blot analysis showed that iNOS could not be detected in unstimulated human cardiac fibroblasts but could be detected in cardiac fibroblasts exposed to IL-1beta. CONCLUSION: IL-1beta increased MMP-2 activity and transcription of human cardiac fibroblasts via iNOS-NO pathway.

Safety and efficacy of autologous endothelial progenitor cells transplantation in children with idiopathic pulmonary arterial hypertension: open-label pilot study.

Experimental data suggest that transplantation of EPCs attenuates monocrotaline-induced pulmonary hypertension in rats and dogs. In addition, our previous studies suggested that autologous EPC transplantation was feasible, safe, and might have beneficial effects on exercise capacity and pulmonary hemodynamics in adults with IPAH. Thus, we hypothesized that transplantation of EPCs would improve exercise capacity and pulmonary hemodynamics in children with IPAH. Thirteen children with IPAH received intravenous infusion of autologous EPCs. The right-sided heart catheterization and 6-MWD test were performed at baseline and at the time of 12 wk after cell infusion. At the time of 12 wk, mPAP decreased by 6.4 mmHg from 70.3 +/- 19.0 to 63.9 +/- 19.3 mmHg (p = 0.015). PVR decreased by approximately 19% from 1118 +/- 537 to 906 +/- 377 dyn s/cm(5) (p = 0.047). CO increased from 3.39 +/- 0.79 to 3.85 +/- 0.42 L/min (p = 0.048). The 6-MWD increased by 39 m from 359 +/- 82 to 399 +/- 74 m (p = 0.012). NYHA functional class also improved. There were no severe adverse events with cell infusion. The small pilot study suggested that intravenous infusion of autologous EPCs was feasible, safe, and associated with significant improvements in exercise capacity, NYHA functional class, and pulmonary hemodynamics in children with IPAH. Confirmation of these results in a randomized controlled trial are essential.

Proteomic analysis of the serum in patients with idiopathic pulmonary arterial hypertension.

Idiopathic pulmonary arterial hypertension (IPAH) is a rare disease of unknown etiology. The exact pathogenesis of pulmonary arterial hypertension is still not well known. In the past decades, many protein molecules have been found to be involved in the development of IPAH. With proteomic techniques, profiling of human plasma proteome becomes more feasible in searching for disease-related markers. In present study, we showed the protein expression profiles of the serum of IPAH and healthy controls after depleting a few high-abundant proteins in serum. Thirteen spots had changed significantly in IPAH compared with healthy controls and were identified by LC-MS/MS. Alpha-1-antitrypsin and vitronectin were down-regulated in IPAH and may be valuable candidates for further explorations of their roles in the development of IPAH.

Transplantation of autologous endothelial progenitor cells may be beneficial in patients with idiopathic pulmonary arterial hypertension: a pilot randomized controlled trial.

OBJECTIVES: The goal of this study was to investigate the feasibility, safety, and initial clinical outcome of intravenous infusion of autologous endothelial progenitor cells (EPCs) in patients with idiopathic pulmonary arterial hypertension (IPAH). BACKGROUND: Experimental data suggest that transplantation of EPCs attenuates monocrotaline-induced pulmonary hypertension in rats and dogs. In addition, clinical studies suggest that autologous progenitor cell transplantation is feasible and safe in patients with ischemic diseases. METHODS: We conducted a prospective, randomized trial comparing the effects of EPC transplantation plus conventional therapy with those of conventional therapy alone in patients with IPAH. The primary end point was change in the 6-min walk distance using a standardized protocol. The secondary end points were changes in hemodynamic variables as assessed by right heart catheterization. RESULTS: After 12 weeks of follow-up, the mean distance walked in 6 min increased by 48.2 m in the cell infusion group (from 263 +/- 42 m to 312 +/- 34 m), and an increase of 5.7 m occurred in the conventional therapy group (from 264 +/- 42 m to 270 +/- 44 m). The mean difference between the 2 groups was 42.5 m (95% confidence interval 28.7 to 56.3 m, p < 0.001). The patients in the cell infusion group also had significant improvement in mean pulmonary artery pressure, pulmonary vascular resistance, and cardiac output. There were no severe adverse events with cell infusion. CONCLUSIONS: This preliminary study showed that intravenous infusion of autologous EPCs seemed to be feasible and safe, and might have beneficial effects on exercise capacity and pulmonary hemodynamics in patients with IPAH. (Safety and Efficacy Study of Transplantation of EPCs to Treat Idiopathic Pulmonary Arterial Hypertension; http://www.clinicaltrials.gov/ct/show/NCT00257413?order=1; NCT00257413).

A novel splice mutation of HERG in a Chinese family with long QT syndrome.

Congenital long QT syndrome (LQTS) is a genetically heterogeneous disease in which six ion-channel genes have been identified. The phenotype-genotype relationships of the HERG (human ether-a-go-go-related gene) mutations are not fully understood. The objective of this study is to identify the underlying genetic basis of a Chinese family with LQTS and to characterize the clinical manifestations properties of the mutation. Single strand conformation polymorphism (SSCP) analyses were conducted on DNA fragments amplified by polymerase chain reaction from five LQT-related genes. Aberrant conformers were analyzed by DNA sequencing. A novel splice mutation in C-terminus of HERG was identified in this Chinese LQTS family, leading to the deletion of 11-bp at the acceptor splice site of Exon9 [Exon9 IVS del (-12-->-2)]. The mutation might affect, through deficient splicing, the putative cyclic nucleotide binding domain (CNBD) of the HERG K(+) channel. This mutation resulted in a mildly affected phenotype. Only the proband had a history of syncopes, while the other three individuals with long QT interval had no symptoms. Two other mutation carriers displayed normal phenotype. No sudden death occurred in the family. The 4 affected individuals and the two silent mutation carriers were all heterozygous for the mutation. It is the first splice mutation of HERG reported in Chinese LQTS families. Clinical data suggest that the CNBD mutation may be less malignant than mutations occurring in the pore region and be partially dominant over wild-type function.

[Cloning, expression and sequence analysis and tissue distribution of angiotensin-converting enzyme 2 (ACE2) gene in adult mice].

OBJECTIVE: o clone angiotensin-converting enzyme 2(ACE2) gene, to analyze its amino acids and nucleotides sequence and to investigate tissue distribution of ACE2 in adult mice. METHODS: The full-length ACE2 encoding sequence was amplified from the RNA of mice kidney tissue by RT-PCR technique, cloned into plasmid pGEM-T easy, then subcloned into plasmid pcDNA3.1+. After identification of DNA sequence, the recombinant plasmid pmACE2 was transfected into Cos7 cells with lipofectin reagent. The transient expression of ACE2 molecule was detected by SDS-PAGE. Sequence analysis was conducted with CLUSTALX program. Tissue distribution of ACE2 in mice was detected by RT-PCR. RESULTS: A fragment about 2.6 kb was amplified and the recombinant plasmid pmACE2 was confirmed by two-enzyme digesting and DNA sequencing. The cloned DNA sequence was consistent with that previously reported, except for 3 variations: A701G, T1102C and T1330C. SDS-PAGE proved that expression of a soluble, truncated products form of ACE2 was a glycoprotein of approximately 80 kD in Cos7 cells. The predicted mice ACE2 sequence contained an N-terminal signal sequence (amino acid residues 1-18), a single HHEMGHIQ zinc-binding domain (amino acid residues 373-380) and C-terminal membrane anchor (amino acid residues 738-765). Mice ACE2 showed 84 % identity with that of human, and 90 % identity with that of rat. Expression of ACE2 was the greatest in lungs, hearts and kidneys, and moderate levels were also detected in testes and livers. CONCLUSION: Mice ACE2 gene has been cloned and successfully expressed in vitro. The tissue-specific expression of ACE2 in different species is not identical.

[Effects of Ginkgo biloba extract on number and activity of endothelial progenitor cells from peripheral blood].

AIM: To investigate whether Ginkgo biloba extract can augment endothelial progenitor cell (EPC) number, and promote EPC proliferation, migration and adhesion. METHODS: Total mononuclear cells (MNCs) were isolated from peripheral blood by Ficoll density gradient centrifugation, and then the cells were plated on fibronectin-coated culture dishes. After 7 days of culture, attached cells were stimulated with Ginkgo biloba extract (10, 25 and 50 mg x L(-1)) or vehicle control for the respective time points (6, 12, 24 and 48 h). EPC were characterized as adherent cells double positive for DiLDL-uptake and lectin binding by direct fluorescent staining under a laser scanning confocal microscope. EPC were further documented by demonstrating the expression of CD34, VEGFR-2 and AC133 with flow cytometry. EPC proliferation, migration and in vitro vasculogenesis activity were assayed with MTT assay, modified Boyden chamber assay and in vitro vasculogenesis kit, respectively. EPCs adhesion assay was performed by replating MNCs on fibronectin-coated dishes, and then counting adherent cells. RESULTS: Incubation of isolated human MNCs with Ginkgo biloba extract increased the number of EPC, maximum at 25 mg x L(-1), 24 hours (approximately 1-fold increase, P < 0.01). In addition, Ginkgo biloba extract promotes EPC proliferative, migratory, adhesive and in vitro vasculogenesis capacity. CONCLUSION: Ginkgo biloba may promote EPC augmentation and enhance its functional activity.

[Effects of puerarin on number and activity of endothelial progenitor cells from peripheral blood].

OBJECTIVE: To investigate whether puerarin can augment endothelial progenitor cells (EPCs) numbers, promote EPC proliferation, migration and adhesion. METHOD: Total mononuclear cells (MNCs) were isolated from peripheral blood by Ficoll density gradient centrifugation, and then the cells were plated on fibronectin-coated culture dishes. After 7 days culture, attached cells were stimulated with puerarin (to make a series of final concentrations: 0. 1, 0.5, 1, 3 mmol x L(-1)) or vehicle control for the respective time points (6, 12, 24, 48 h). EPCs were characterized as adherent cells double positive for DiLDL-uptake and lectin binding by direct fluorescent staining under a laser scanning confocal microscope. EPCs proliferation, migration and in vitro vasculogenesis activity were assayed with MT assay, modified Boyden chamber assay and in vitro vasculogenesis kit, respectively. EPCs adhesion assay was performed by replating those on fibronectin-coated dishes, then adherent cells were counted. RESULT: Incubation of isolated human MNCs with puerarin dose increased the number of EPCs, maximum at 3 mmol x L(-1), 24 hours (approximately 1-fold increase, P < 0.01). In addition, puerarin also promoted EPC proliferative, migratory, adhesive and in vitro vasculogenesis capacity. CONCLUSION: Puerarin can augment the number of EPCs with enhanced functional activity.

[Identification of a novel mutation at the point of low density lipoprotein receptor gene from a subject with familial hypercholesterolemia].

Family hypercholesterolemia (FH) is a genetic disorder caused by mutation in the low density lipoprotein receptor (LDLR) gene. It is characterized by a high concentration of low density lipoprotein (LDL), which frequently gives rise to tendon xanthenes and premature coronary artery disease. We studied a FH family ,which was diagnosed by clinical features and blood lipid tests. The Total cholesterol level of the family was 19.05 mmol/L and the LDL level was 17.06 mmol/L in the proband homozygous FH subjects, while the total cholesterol was 7.96 mmol/L and LDL was 5.55 mmol/L in the heterozygous FH subjects. DNA segments amplified with PCR were sequenced in heterozygous and homozygous FH patients. Two novel identical mutation alleles of GAG683GCG, which caused an amino acid change from Glu to Ala, were detected in Exon4 of LDL receptor gene in homozygous proband. DNA sequencing revealed that the proband's parents were heterozygotes with the same mutational alleles as the proband. These results are in coincidence with the clinical diagnoses. Moreover Epstein-Barr virus transformed lymphocytes (EBV-Ls) were derived by routine virus infection transforming protocol. The cells bounded with the fluorescently conjugated LDL were measured by fluorescence flow cytometry. The ratios of functional LDLR in EBV-Ls originated from homozygous FH, heterozygous FH and normal control were 7.02%, 62.64% and 84.69%, respectively. As a result, the homozygous FH patient's LDLR had 8.29% and the heterozygous FH patient's LDLR had 73.96% of the activity of the control. It is apparent that LDL receptor activity of homozygous FH subject is significantly lower than normal control. The data from fluorescence flow cytometry analysis of EBV-Ls strongly support the clinical diagnoses and the results of DNA sequencing. In accordance with the updated version of UMD-LDLR, the mutant GAG683GCG in Exon4 of LDLR gene which we have identified is a novel mutation of the LDLR gene in human with hypercholesterolemia.

Effects of puerarin on number and activity of endothelial progenitor cells from peripheral blood.

AIM: To investigate whether puerarin can augment endothelial progenitor cells (EPCs) numbers, promote EPC proliferative, migratory, adhesive, and in vitro vasculogenesis capacity. METHODS: EPCs were characterized as adherent cells by double staining of DiLDL-uptake and lectin binding under a laser scanning confocal microscope. Expression of KDR, VEGFR-2, and AC133 was detected by flow cytometry. EPCs proliferation, migration and in vitro vasculogenesis were determined with MTT assay, modified Boyden chamber assay, and in vitro vasculogenesis kit, respectively. EPCs adhesive assay was performed by replating those on fibronectin-coated dishes, then adherent cells were counted. RESULTS: Incubation of isolated human MNCs with puerarin 0.1-3 mmol/L increased the number of EPCs, EPC proliferative, migratory, adhesive, and in vitro vasculogenesis capacity in a concentration- and time-dependent manner, which reached maximum at 3 mmol/L, 24 h (approximately 1-fold increase, P<0.01). CONCLUSION: Puerarin enhanced EPCs functional activity.

Statins contribute to enhancement of the number and the function of endothelial progenitor cells from peripheral blood.

The aim of the present study was to investigate whether fluvastatin augments the number of endothelial progenitor cells (EPCs), and promotes EPCs proliferation, migration and adhesion. Total mononuclear cells (MNCs) were isolated from peripheral blood by Ficoll density gradient centrifugation. The cells were then plated on fibronectin-coated culture dishes. After being cultured for 7 d, the attached cells were stimulated with fluvastatin (final concentrations: 0.01, 0.1, 1, 10 micromol/L), simvastatin (1 micromol/L) or a vehicle for the respective time points (6, 12, 24 and 48 h). EPCs were characterized as adherent cells double positive for DiLDL-uptake and lectin binding by direct fluorescent staining under a laser scanning confocal microscope. EPCs were further documented by demonstrating the expression of KDR, VEGFR-2 and AC133 with flow cytometry. EPCs proliferation, migration and in vitro vasculogenesis activity were assayed by MTT assay, modified Boyden chamber assay and in vitro vasculogenesis kit, respectively. EPCs adhesion assay was performed by replating it on fibronectin-coated dishes, and the adherent cells were then counted. In addition, we also studied EPCs culture assay of peripheral blood from fluvastatin-treated animals in vivo. Incubation of isolated human MNCs with fluvastatin dose- and time-dependently increased the number of EPCs, while reached the maximum 24 h after the administration at 1 micromol/L, (2.5-fold increase, P<0.05). Moreover, treatment of rats with fluvastatins elevated the number of EPCs (3-fold increase, P<0.05), thus extending the in vitro data. In addition, fluvastatin also promoted EPC proliferation, migration, adhesion and in vitro vasculogenesis in a concentration-dependent manner. The effects of fluvastatin on EPCs were compared with those of simvastatin at the same concentration (1 micromol/L), with a result of no statistical difference. The results of the present study define a novel mechanism of the action of statins: the augmentation of EPCs with enhanced functional activity.

Single nucleotide polymorphisms of the SCN5A gene in Han Chinese and their relation with Brugada syndrome.

BACKGROUND: Mutations in the cardiac sodium channel gene (SCN5A) may lead to a broad spectrum of familial arrhythmias, including long QT syndrome (LQTS), idiopathic ventricular fibrillation (IVF), and isolated cardiac conduction diseases. Recent studies have shown that polymorphisms in the SCN5A gene also play an important role in the manifestation of disorders involving cardiac excitability. In this study, we investigated the polymorphisms of the SCN5A gene in Han Chinese and its relation to Brugada syndrome (BS). METHODS: Genomic DNA was isolated from 120 unrelated healthy volunteers and 48 unrelated Brugada syndrome patients by means of standard procedures. All exons including the putative splicing sites of the SCN5A gene were amplified by PCR and sequenced directly or after subcloning using an ABI Prism 377 DNA sequencer. RESULTS: A total of 5 single nucleotide polymorphisms (SNPs) were identified in the Han Chinese population, including 3 novel ones: G87A(A29A), 4245 + 82A > G, and G6174A. The allele frequencies of each SNP in the Han Chinese population were as follows: G87A (A29A) 27.5%, A1673G (H558R) 10.4%, 4245 + 82A > G 32.8%, C5457T (D1819D) 41.3%, and G6174A 44.9%. S1102Y and 10 other SNPs identified in other ethnic populations were not detected in this study. There was no significant difference in the allele frequency of A1673G (H558R) between different ethnic populations (all P > 0.5). On the other hand, the allele frequency of C5457T (D1819D) among Han Chinese was similar to its frequency among Japanese (P > 0.5), but higher than that among Americans (P < 0.005). The allele G1673 (R558) was over-represented in BS patients compared to controls (P < 0.005), but there was no significant difference in genotype frequencies at this locus. There were also no differences in either the allele or genotype frequencies of the 4 other identified SNPs when comparing BS patients with healthy controls. CONCLUSIONS: The distribution of SCN5A SNPs may vary between different ethnicities. The polymorphism of A1673G might be associated with BS and may contribute to a susceptibility to BS in Han Chinese.

[Single nucleotide polymorphism in SCN5A and the distribution in Chinese Han ethnic group].

Mutations in voltage-gated sodium channel type (SCN5A) may evoke severe, life-threatening disturbances in cardiac rhythm, including long QT syndrome, idiopathic ventricular fibrillation (Brugada Syndrome), and isolated cardiac conduction disease. There is increasing awareness of the role of common polymorphisms in altering gene function and in susceptibility to diseases. The aim of the present study was to investigate single nucleotide polymorphism (SNP) in SCN5A gene and the distribution of these identified SNPs in Chinese Han nationality. SCN5A gene was sequenced by fluorescent labeling automatic sequencing method in 120 unrelated samples from Han nationality in South China. Allele frequency distribution was tested by Hardy-Weinberg equilibrium. The results showed that a total of 5 SNPs were identified in SCN5A gene, including three SNPs in code region, one SNP in regulatory region and the other in intron 23 adjacent to donor splicing site. The distribution of the SNPs in SCN5A gene was uneven. These allele frequencies in Han population of South China were as follows: G87A (A29A) 27.5%, A1673G (H588R) 10.4%, 4245+82A>G 32.8%, C5457T (D1819D) 41.3% and G6174A 44.9% respectively. The SNPs G87A (A29A), 4245+82A>G and G6174A were reported for the first time. There was no significant difference in the allele frequency of A1673G (H558R) within different ethical populations (P>0.05). C5457T (D1819D) allele frequency of Han population in South China was similar to that observed in Japanese (P>0.5), but higher than that in American (p<0.005). There was no significant difference in the distribution of the SNPs between male group and female group (all p>0.05). S1102Y and other 10 SNPs identified in other ethnic populations have not been detected in Chinese Han population. The allele distribution of SNPs was in good unity with the Hardy-Weinberg equilibrium. It is suggested that the SNP distribution of SCN5A gene varies within different nationalities. These data will be of use for genetic association studies of acquired arrythmias and investigation of sensitivity to drug therapy.

[Dependence of ventricular wallstress-induced refractoriness changes on pacing cycle lengths and its mechanism].

The aim of this article was to investigate the dependence of ventricular wallstress-induced refractoriness changes on pacing cycle lengths and its mechanism in anaesthetized rabbits. The rabbit heart preparation was used. The left ventricular afterload was increased by partially clipping the root of the ascending aorta. The changes in effective refractory periods (ERP) induced by the left ventricular afterload rising were examined at different pacing cycle lengths (1000, 500, 300 and 200 ms). In addition, the effect of streptomycin on these changes was also observed. The results are as follows: (1) The rising of left ventricular afterload led to marked changes in ERP at rapidly pacing cycle lengths (300 ms, 21+/-5 ms, 17.0%; 200 ms, 19+/-3 ms, 18.8%. P<0.01) than at slow ones (1000 ms, 3+/-2 ms, 1.5%; 500 ms, 7+/-3 ms, 4.0%. P>0.05); (2) Streptomycin inhibited the changes caused by the left ventricular afterload rising at pacing cycle lengths 300 ms and 200 ms (P>0.05). It is suggested that ventricular wallstress-induced refractoriness changes are pacing cycle length-dependent, and the effect of streptomycin appears to be consistent with the inhibition of stretch-activated ion channels.