Developing and Validating a Simple Risk Score for Patients with Acute Myocardial Infarction.

INTRODUCTION: Mortality from acute myocardial infarction (AMI) remains substantial. The current study is aimed at developing a novel simple risk score for AMI. METHODS: The Coronary Artery Tree description and Lesion EvaluaTion (CatLet) extended validation trial (ChiCTR2000033730) and the CatLet validation trial (ChiCTR-POC-17013536), both being registered with chictr.org, served as the derivation and validation datasets, respectively. Both datasets included 1,018 and 308 patients, respectively. They all suffered from AMI and underwent percutaneous intervention (PCI). The endpoint was 4-year all-cause death. Lasso regression analysis was used for covariate selection and coefficient estimation. RESULTS: Of 26 candidate predictor variables, the four strongest predictors for 4-year mortality were included in this novel risk score with an acronym of BACEF (serum alBumin, Age, serum Creatinine, and LVEF). This score was well calibrated and yielded an AUC (95% CI) statistics of 0.84 (0.80-0.87) in internal validation, 0.89 (0.83-0.95) in internal-external (temporal) validation, and 0.83 (0.77-0.89) in external validation. Notably, it outperformed the ACEF, ACEF II, GRACE scores with respect to 4-year mortality prediction. CONCLUSION: A simple risk score for 4-year mortality risk stratification was developed, extensively validated, and calibrated in patients with AMI. This novel BACEF score may be a useful risk stratification tool for patients with AMI.

Laparoscopic based renal denervation in a canine neurogenic hypertension model.

BACKGROUND: Previous renal denervation (RDN) studies showed controversial results in reducing blood pressure. The aim of this study was to provide evidence supporting the effectiveness of laparoscopic-based renal denervation (L-RDN) in treating hypertension. METHODS: Sixteen Beagle dogs were randomly divided into RDN group (n = 12) and sham group (n = 4). Neurogenic hypertension was generated in all dogs via carotid artery route. L-RDN was performed in the RDN group, with sham operation performed as a control. Blood pressure (BP) changes were recorded at 2, 4, 6, and 8 weeks after the procedure. Changes in serum creatinine (sCr), blood urea nitrogen (BUN) and level of norepinephrine (NE) were analyzed. Histological changes of kidney and renal arteries were also evaluated. RESULTS: BP and NE levels were significantly elevated after hypertension induction (p < 0.01). Systolic and diastolic BP of RDN group were decreased by 15.5 mmHg and 7.3 mmHg (p < 0.0001 and p = 0.0021, respectively) at the eighth week after L-RDN. Invasive systolic and diastolic BP of RDN group were significantly decreased by 14.5 mmHg and 15.3 mmHg (p < 0.0001). In contrast, there was no significant decrease in blood pressure in the sham group. In addition, RDN group but not the sham group showed a significant decrease in NE levels (p < 0.001), while no significant changes in sCr and BUN were observed in both groups. Pathological examinations showed no discernible damage, tear, or dissection to the renal arteries in RND group. CONCLUSIONS: L-RDN lowered BP and NE levels in hypertensive dogs without affecting renal artery morphology and kidney function.

Ischemia triggered ATP release through Pannexin-1 channel by myocardial cells activates sympathetic fibers.

The cardiovascular system is extensively innervated by the autonomic nervous system, and the autonomic modulation including sympathetic innervation is crucial to the function of heart during normal and ischemic conditions. Severe myocardial ischemia could cause acute myocardial infarction, which is one of the leading diseases in the world. Thus studying the sympathetic modulation during ischemia could reduce the probability of myocardial infarction and further heart failure. The neurotransmitter ATP is released by myocardial cells during ischemia; however, the effect of ATP release remains elusive. We examined whether ATP released during ischemia functions as a neurotransmitter that activates sympathetic nerve in the heart. A novel technique of recording the sympathetic fiber calcium imaging in mouse cardiac tissue slices was used. We have applied the Cre/loxP system to specifically express GCaMP3, a genetically encoded calcium indicator, in the sympathetic nerve. Using this technique, we found that ATP released by myocardial cells through Pannexin-1 channel during ischemia could evoke calcium responses in cardiac sympathetic nerve fibers. Our study provides a new approach to study the cell and nerve interaction in the cardiac system, as well as a new understanding of ATP function during ischemia.

GATA-4 induces changes in electrophysiological properties of rat mesenchymal stem cells.

BACKGROUND: Transplanted mesenchymal stem cells (MSC) can differentiate into cardiac cells that have the potential to contribute to heart repair following ischemic injury. Overexpression of GATA-4 can significantly increase differentiation of MSC into cardiomyocytes (CM). However, the specific impact of GATA-4 overexpression on the electrophysiological properties of MSC-derived CM has not been well documented. METHODS: Adult rat bone marrow MSC were retrovirally transduced with GATA-4 (MSC(GATA-4)) and GFP (MSC(Null)) and subsequently co-cultured with neonatal rat ventricular cardiomyocytes (CM). Electrophysiological properties and mRNA levels of ion channels were assessed in MSC using patch-clamp technology and real-time PCR. RESULTS: MSC(GATA-4) exhibited higher levels of the TTX-sensitive Na(+) current (INa.TTX), L-type calcium current (ICa.L), transient outward K(+) current (Ito), delayed rectifier K(+) current (IKDR) and inwardly rectifying K(+) current (IK1) channel activities reflective of electrophysiological characteristics of CM. Real-time PCR analyses showed that MSC(GATA-4) exhibited upregulated mRNA levels of Kv1.2, Kv2.1, SCN2a1, CCHL2a, KV1.4 and Kir1.1 channels versus MSC(Null). Interestingly, MSC(GATA-4) treated with IGF-1 neutralizing antibodies resulted in a significant decrease in Kir1.1, Kv2.1, KV1.4, CCHL2a and SCN2a1 channel mRNA expression. Similarly, MSC(GATA-4) treated with VEGF neutralizing antibodies also resulted in an attenuated expression of Kv2.1, Kv1.2, Kv1.4, Kir1.1, CCHL2a and SCN2a1 channel mRNAs. CONCLUSIONS: GATA-4 overexpression increases Ito, IKDR, IK1, INa.TTX and ICa.L currents in MSC. Cytokine (VGEF and IGF-1) release from GATA-4 overexpressing MSC can partially account for the upregulated ion channel mRNA expression. GENERAL SIGNIFICANCE: Our results highlight the ability of GATA4 to boost the cardiac electrophysiological potential of MSC.

CatLet score and clinical CatLet score as predictors of long-term outcomes in patients with acute myocardial infarction presenting later than 12 hours from symptom onset.

BACKGROUND: Our recently developed Coronary Artery Tree description and Lesion EvaluaTion (CatLet) angiographic scoring system is unique in its description of the variability in the coronary anatomy, the degree of stenosis of a diseased coronary artery, and its subtended myocardial territory, and can be utilized to predict clinical outcomes for patients with acute myocardial infarction (AMI) presenting ≤12 h after symptom onset. The current study aimed to assess whether the Clinical CatLet score (CCS), as compared with CatLet score (CS), better predicted clinical outcomes for AMI patients presenting >12 h after symptom onset. METHODS: CS was calculated in 1018 consecutive AMI patients enrolled in a retrospective registry. CCS was calculated by multiplying CS by the ACEF I score (age, creatinine, and left ventricular ejection fraction). Primary endpoint was major adverse cardiac events (MACEs) at 4-year-follow-up, a composite of cardiac death, myocardial infarction, and ischemia-driven revascularization. RESULTS: Over a 4-year follow-up period, both scores were independent predictors of clinical outcomes after adjustment for a broad spectrum of risk factors. Areas-under-the-curve (AUCs) for CS and CCS were 0.72(0.68-0.75) and 0.75(0.71-0.78) for MACEs; 0.68(0.63-0.73) and 0.78(0.74-0.83) for all-cause death; 0.73(0.68-0.79) and 0.83(0.79-0.88) for cardiac death; and 0.69(0.64-0.73) and 0.75(0.7-0.79) for myocardial infarction; and 0.66(0.61-0.7) and 0.63(0.58-0.68) for revascularization, respectively. CCS performed better than CS in terms of the above-mentioned outcome predictions, as confirmed by the net reclassification and integrated discrimination indices. CONCLUSIONS: CCS was better than CS to be able to risk-stratify long-term outcomes in AMI patients presenting >12 h after symptom onset. These findings have indicated that both anatomic and clinical variables should be considered in decision-making on management of patients with AMI presenting later.

LncRNA HOTAIR promotes myocardial fibrosis in atrial fibrillation through binding with PTBP1 to increase the stability of Wnt5a.

BACKGROUND: Atrial fibrillation (AF) is one of the most common arrhythmia in clinical practice, and atrial fibrosis is the important mediator in AF. LncRNA HOTAIR was reported to be up-regulated in AF, while the underlying mechanism of HOTAIR in AF remains unclear. METHODS: In vitro and in vivo AF model was established. qRT-PCR and Western blotting were used to assess the mRNA expression (HOTAIR, Wnt5a and PTBP1) and protein levels (Wnt5a, collagen I/III, α-SMA, CTGF, p-ERK, ERK, p-JNK, and JNK), respectively. MTT, CCK8, transwell assay was used to test cell viability, proliferation and migration, respectively. RIP assay assessed the correlation among HOTAIR, PTBP1 and Wnt5a. The level of α-SMA was detected by immunofluorescence. HE and Masson staining detected the histological changes and fibrosis in mouse heart tissues. RESULTS: Ang II significantly increased the viability of atrial fibroblasts. The levels of HOTAIR and Wnt5a in fibroblasts were up-regulated by Ang II. HOTAIR silencing or Wnt5a significantly inhibited Ang II-induced proliferation, migration and fibrosis in fibroblasts. HOTAIR silencing repressed Wnt5a-mediated ERK and JNK signaling pathway, and Wnt5a partially abolished the effect of HOTAIR silencing on cell proliferation, migration and fibrosis. Meanwhile, HOTAIR could increase the mRNA stability of Wnt5a via recruiting PTBP1. Furthermore, HOTAIR knockdown notably inhibited the fibrosis in heart tissues of AF mice via regulation of Wnt signaling. CONCLUSION: HOTAIR could promote atrial fibrosis in AF through binding with PTBP1 to increase Wnt5a stability. Our study might shed new insights on exploring new strategies against AF.

J-shaped association between serum albumin levels and long-term mortality of cardiovascular disease: Experience in National Health and Nutrition Examination Survey (2011-2014).

Background: Cardiovascular disease (CVD) is a constellation of heart, brain, and peripheral vascular diseases with common soil hypothesis of etiology, and its subtypes have been well-established in terms of the albumin-mortality association. However, the association between albumin and the mortality of CVD as a whole remains poorly understood, especially the non-linear association. We aimed to investigate the association of albumin levels with long-term mortality of CVD as a whole. Materials and methods: This study included all CVD patients who participated in the National Health and Nutrition Examination Survey (NHANES 2011-2014). CVD was defined as coronary heart disease, stroke, heart failure, or any combination of these two or three diseases. Serum albumin was tertile partitioned: tertile 1, <4.1; tertile 2, 4.1-4.3; and tertile 3, >4.3 g/dl. COX proportional hazards model was used to assess the association between the serum albumin levels and CVD mortality. Restricted cubic spline (RCS) curves were used to explore the non-linear relationship. Results: A total of 1,070 patients with CVD were included in the analysis, of which 156 deaths occurred during a median 34 months of follow-up. On a continuous scale, per 1 g/dl albumin decrease was associated with an adjusted HR (95% CI) of 3.85 (2.38-6.25). On a categorical scale, as compared with tertile 3, the multivariable adjusted hazard ratio (95% CI) was 1.42 (0.74-2.71) for the tertile 2, and 2.24 (1.20-4.16) for the tertile 1, respectively, with respect to mortality. RCS curve analysis revealed a J-shaped association between albumin and CVD mortality. Conclusion: A J-shaped association between low serum albumin levels and increased long-term mortality of CVD has been revealed. This J-shaped association's implications for CVD prevention and treatment are deserving of being further studied.

The predictive value of CatLet© angiographic scoring system for long-term prognosis in patients with acute myocardial infarction presenting > 12 h after symptom onset.

Background: We have recently developed the C oronary A rtery T ree description and L esion E valua T ion (CatLet©) angiographic scoring system, which is capable of accounting for the variability in coronary anatomy, and risk-stratifying patients with coronary artery disease. This study aimed to clarify whether the CatLet score had a predictive value for long-term prognosis in patients with acute myocardial infarction (AMI) presenting > 12 h after symptom onset. Materials and methods: The CatLet score was calculated for 1,018 consecutively enrolled AMI patients, who were divided into 3 groups according to the CatLet score tertiles. The primary endpoint was major adverse cardiac events (MACEs), defined as a composite of myocardial infarction, cardiac death, and ischemia-driven revascularization; secondary endpoints were all-cause death, cardiac death, myocardial infarction, and ischemia-driven revascularization. Results: The CatLet score was capable of predicting long-term prognosis at a median 4.9-year follow-up alone or after adjustment for risk factors. Multivariable-adjusted hazard ratios (95% CI)/unit higher score were 1.06 (1.05-1.08) for MACEs, 1.05 (1.03-1.07) for all-cause death, 1.06 (1.04-1.09) for cardiac death, 1.06 (1.04-1.08) for myocardial infarction, and 1.06 (1.04-1.08) for revascularization. The univariate model showed good calibration (χ2 = 8.25, P = 0.4091) and good discrimination (area under ROC curve = 0.7086) for MACEs. Conclusion: The CatLet score is an independent predictor of long-term clinical outcomes of patients with AMI presenting > 12 h after symptom onset (http://www.chictr.org.cn; Registry Number: ChiCTR2000033730).

Atrial Fibrillation Ablation Using Robotic Magnetic Navigation Reduces the Incidence of Silent Cerebral Embolism.

Background: The incidence of silent cerebral embolisms (SCEs) has been documented after pulmonary vein isolation using different ablation technologies; however, it is unreported in patients undergoing with atrial fibrillation (AF) ablation using Robotic Magnetic Navigation (RMN). The purpose of this prospective study was to investigate the incidence, risk predictors and probable mechanisms of SCEs in patients with AF ablation and the potential impact of RMN on SCE rates. Methods and Results: We performed a prospective study of 166 patients with paroxysmal or persistent AF who underwent pulmonary vein isolation. Patients were divided into RMN group (n = 104) and manual control (MC) group (n = 62), and analyzed for their demographic, medical, echocardiographic, and risk predictors of SCEs. All patients underwent cerebral magnetic resonance imaging within 48 h before and after the ablation procedure to assess cerebral embolism. The incidence and potential risk factors of SCEs were compared between the two groups. There were 26 total cases of SCEs in this study, including 6 cases in the RMN group and 20 cases in the MC group. The incidences of SCEs in the RMN group and the MC group were 5.77 and 32.26%, respectively (X2 = 20.63 P < 0.05). Univariate logistic regression analysis demonstrated that ablation technology, CHA2DS2-VASc score, history of cerebrovascular accident/transient ischemic attack, and low ejection fraction were significantly associated with SCEs, and multivariate logistic regression analysis showed that MC ablation was the only independent risk factor of SCEs after an AF ablation procedure. Conclusions: Ablation technology, CHA2DS2-VASc score, history of cerebrovascular accident/transient ischemic attack, and low ejection fraction are associated with SCEs. However, ablation technology is the only independent risk factor of SCEs and RMN can significantly reduce the incidence of SCEs resulting from AF ablation. Clinical Trial Registration: ChiCTR2100046505.

Inter- and intra-observer variability for the assessment of coronary artery tree description and lesion EvaluaTion (CatLet©) angiographic scoring system in patients with acute myocardial infarction.

BACKGROUND: Previously, we developed a novel Coronary Artery Tree description and Lesion EvaluaTion (CatLet©) angiographic scoring system, which was capable of accounting for the variability in the coronary anatomy and assisting in the risk-stratification of patients with acute myocardial infarction (AMI). Our preliminary study revealed that the CatLet score better predicted clinical outcomes for AMI patients than the Synergy between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery score. However, the reproducibility of the CatLet score in both inter- and intra-observer remains to be evaluated. METHODS: A total of 30 consecutive AMI patients, admitted in September of 2015, were independently assessed by two experienced interventional cardiologists to evaluate the inter-observer reproducibility of the CatLet score. Another set of 49 consecutive AMI patients, admitted between September and October in 2014, were assessed by one of the two interventional cardiologists on two occasions 3 months apart to evaluate the intra-observer reproducibility of the CatLet score. The weighted kappa was used to express the degree of agreement. RESULTS: The weighted kappa values (95% confidence interval) for the intra- and inter-observer reproducibility of the CatLet Score were 0.82 (0.59-1.00, Z = 7.23, P < 0.001) and 0.86 (0.54-1.00, Z = 5.20, P < 0.001), respectively, according to the tertile analysis (≤14, 15-22, >22). Regarding the adverse characteristics pertinent to lesions and dominance parameters, the kappa values for the inter-observer variability were 0.80 (0.56-1.00, Z = 6.47, P < 0.001) for total number of lesions, 0.57 (0.28-0.85, Z = 3.03, P < 0.001) for bifurcation, 0.69 (0.43-0.96, Z = 5.06, P < 0.001) for heavy calcification, 1.00 (0.72-1.00, Z = 6.93, P < 0.001) for tortuosity, 0.54 (0.26-0.82, Z = 3.78, P < 0.001) for thrombus, 0.69 (0.48-0.91, Z = 6.29, P < 0.001) for right coronary artery dominance, 0.69 (0.41-0.96, Z = 4.91, P < 0.001) for left anterior descending artery length, and 0.22 (0.06-0.51, Z = 1.56, P = 0.06) for diagonal size. Equivalent values for the intra-observer variability were moderate to almost perfect (range 0.54-1.00). CONCLUSIONS: The reproducibility of the CatLet angiographic scoring system for evaluation of the coronary angiograms ranged from substantial to excellent. The high reproducibility of the CatLet angiographic scoring system will boost its clinical application to patients with AMI.

[Construction of genetic linkage maps of silver birch based on AFLP markers].

Based on the inheritance and segregation of amplified fragment length polymorphism (AFLP) markers, the first middensity linkage map for silver birch was constructed using a pseudotestcross mapping strategy. A segregating population including 80 progenies from the cross between Betula platyphylla Suk and B. pendula Roth was obtained. A set of 64 primer combinations were screened, and 34 pair primer combinations were selected to generate AFLP markers within a sample of 80 F1 progenies. A total of 451 segregating sites were identified. Among them, 362 belonged to 1:1 segregating site, and 41 belonged to 3:1 segregating site, 20 belonged to 1:3 segregating site, and others were found distorted from the Mondelian ratio. Altogether 362 sites segregating 1:1 (testcross configuration) were used to construct parent-specific linkage maps, 201 for B. platyphylla and 161 for B. pendula. One linkage maps resulted consisted of 201 marker sites in 14 groups with four or more sites per group, 10 triples and 14 pairs for B. platyphylla, which covered a map distance about 1 296.1 cM (Kosambi units), and the average map distance between adjacent markers was 15.5 cM. Another linkage maps resulted consisted of 161 marker site for B. pendula were mapped onto 17 groups with four or more sites per group, 8 triples and 4 pairs, which covered a map distance about 1 035.8 cM, and the average map distance between adjacent markers was 12 cM. Those maps can be used in QTL analysis and molecular assistant selection in birch breeding.

[Defibrillation efficacy of a newly developed automated external defibrillator in a swine ventricular tachycardia/fibrillation model].

OBJECTIVE: The aim of this study was to evaluate the recognition and defibrillation efficiency of a newly developed automated external defibrillator (AED). METHOD: Ventricular tachycardia (VT)/ventricular fibrillation (VF) was induced by alternating current (50 Hz) through an electrode placed on apex of right ventricle in 23 anesthetized swine and recorded, recognized and defibrillated by a newly developed AED. RESULTS: A total of 96 VF was induced and 145 defibrillations were recorded. We analyzed available 167 electrocardiosignal with a total length of 103,740 seconds. The accuracy, sensitivity and the specificity of the AED on VT/VF recognition are 99.5%, 98.2% and 99.6%, respectively. The success rate of defibrillation was 33.4% which increased in proportion to defibrillation energy. The defibrillation threshold of energy is 29.10-116.91 (78.75 +/- 35.64) J, the defibrillation threshold of electric quantity is (0.11 +/- 0.04) C and the defibrillation threshold of voltage is (1216.67 +/- 260.87) V. CONCLUSIONS: This newly developed AED has high sensitivity and the specificity on recognizing VT/VF. The lower success rate of defibrillation of this AED is associated with the low defibrillation energy during defibrillation which needs to be improved on further development.

Hypoxia imaging of patients with acute myocardial infarction by using dual isotopes of 201Tl and 99mTc-HL91.

OBJECTIVE: To evaluate the myocardial ischaemia/viability in patients with acute myocardial infarction (AMI) using the ischaemia-avid agent (99m)Tc-HL91. METHODS: Thirty-three AMI patients received 740 MBq (20 mCi) (99m)Tc-HL91, i.v., first and then 148-185 MBq (4-5 mCi) (201)Tl around 3 h later. The patient underwent initial imaging and 24 h late imaging, 10-15 min and 24 h later, respectively, after intravenous injection of (201)Tl. Myocardial segmental radioactive counts of (99m)Tc-HL91 were quantified by the region of interest technique. The segmental radioactive counts/pixel divided by those of the corresponding left ventricular cavities were ratios, which were compared among normal, ischemic/viable and fixed defect myocardium. The correlation analysis between the segmental scores from (201)Tl imaging and the ratios was performed. RESULTS: The cross-talk of (99m)Tc into (201)Tl could be neglected in the present study. Out of the 33 AMI patients, the (99m)Tc-HL91 image quality analysis classified seven cases into excellent, accounting for 21%, eight cases into good, for 24%, eight cases into fair, for 24%, and 10 cases into poor, for 31%. The ratios were 1.16 (1.01, 1.35) ((median (25th to 75th percentile)), 1.15, 0.20 and 1.01 (0.86, 1.30), respectively, in normal, ischaemic/viable and fixed defect myocardium. Significant differences (chi2=17.2069, P=0.0002) were found in the ratios. The ratios of the ischaemic/viable myocardial segments were significantly higher than those of the fixed defect segments. Unexpectedly, the normal myocardial segments took up (99m)Tc-HL91, too, even slightly higher than the ischaemic/viable myocardial segments. CONCLUSIONS: Myocardial uptake of (99m)Tc-HL91 is perfusion-dependent as well as ischaemia dependent. (99m)Tc-HL91 hypoxia imaging alone is not sufficient to identify ischaemic/viable myocardium. Dual-isotope imaging with (201)Tl and (99m)Tc-HL91 can characterize the myocardium into normal, ischaemic/viable and necrotic (scarred) myocardium.

[Effects of different amlodipine isomers on L-type calcium current of rat ventricular myocytes].

OBJECTIVE: To investigate the effects of different amlodipine isomers on L-type calcium current (ICa-L) and kinetics of rat ventricular myocytes. METHODS: Rat ventricular myocytes were isolated by enzyme digestion. ICa-L, peak currents, I-V curves, steady state activation curves, steady state inactivation curves and recovery curves from inactivation with S-amlodipine, R-amlodipine and R, S-amlodipine at concentrations of 0.1, 0.5, 1, 5, and 10 micromol/L were recorded by whole-cell patch clamp configuration. RESULTS: At the concentrations of 0.1, 0.5, 1, 5, and 10 micromol/L, ICa-L were blocked in a dose-dependent manner by S-amlodipine [(1.5 +/- 0.2)%, (25.4 +/- 5.3)%, (65.2 +/- 7.3)%, (78.4 +/- 8.1)%, and (94.2 +/- 5.0)%] and by R, S-amlodipine [(0.9 +/- 0.1)%, (10.4 +/- 3.2)%, (69.1 +/- 5.3)%, (75.2 +/- 7.0)%, and (81.6 +/- 6.4)%]. I-V curves were significantly shifted upward, steady state activation and inactivation curves were significantly shifted to left by S-amlodipine and R, S-amlodipine (0.1 micromol/L to 10 micromol/L). Recovery time from inactivation was also significantly prolonged by S-amlodipine [(210.1 +/- 19.5) ms, (225.2 +/- 21.3) ms, (241.7 +/- 20.3) ms, (252.3 +/- 24.2) ms, and (282.6 +/- 23.2) ms] and by R, S-amlodipine [(208.7 +/- 17.4) ms, (215.8 +/- 18.3) ms, (225.2 +/- 21.3) ms, (235.8 +/- 22.7) ms, and (252.3 +/- 24.2) ms] in a dose-dependent manner. The observed effects of S-amlodipine were more potent than those of R, S-amlodipine (P < 0.05). However, all these parameters were not affected by R-amlodipine at various concentrations (P > 0.05). CONCLUSION: L-type calcium current of rat ventricular myocytes could be blocked by R, S-amlodipine and S-amlodipine in a dose-dependent manner.

[Genetic linkage map of Betula pendula Roth and Betula platyphylla Suk based on random amplified polymorphisms DNA markers].

Based on the genetic inheritance and segregation of random amplified polymorphism DNA (RAPDs) markers, the first mid-density linkage map for silver birch was constructed by using a pseudo-testcross mapping strategy. A segregating population including 80 progenies from the cross between Betula pendula Roth and B. platyphylla Suk was obtained. A set of 1,200 random oligonucleotide primers were screened, and 208 primers were selected to generate RAPD markers within a sample of 80 F1 progenies. A total of 364 segregating sites were identified. Among them, 307 belonged to 1 : 1 segregating site, and 36 belonged to 3 : 1 segregating site, others were found distorted from the normal 1 : 1 ratio. Altogether 307 sites segregating 1 : 1 (testcross configuration) were used to construct parent-specific linkage maps, 145 for B. pendula and 162 for B. platyphylla. The resulting linkage maps consisted of 145 marker sites in 14 groups (four or more sites per group), 6 triples and 6 pairs for B. pendula, which covered the map distance about 955.6 cM (Kosambi units). The average map distance between adjacent markers was 14.9 cM, and 162 linked marker site for B. platyphylla were mapped onto 15 groups (four or more sites per group), 4 triples and 6 pairs, which covered the map distance about 1,545.8 cM, and the average map distance between adjacent markers was 15.2 cM. Further study is warranted to integrate the two maps to one density map and to locate important genes on the maps.

[Effects of metoprolol on cardiac function and myocyte calcium regulatory protein expressions in rabbits with experimental heart failure].

OBJECTIVE: To investigate the effects of metoprolol on cardiac function and myocyte calcium regulatory protein expressions in rabbits with heart failure. METHODS: Rabbit heart failure model was established by aortic insufficiency induced volume overload followed 14 days later by pressure overload induced by abdominal aorta constricting (HF, n = 11), another 8 rabbits with heart failure were treated with metoprolol (ME) for 6 weeks, sham-operated rabbits (n = 11) served as control. Cardiac function was measured by echocardiography at the end of study. Caffeine-induced calcium transients of myocytes loaded by Fluo-3/AM were observed under Laser scanning confocal microscope. Calcium regulatory protein expression was determined by Western blot analysis. RESULTS: Compared to control animals, the ejection fractions [EF, (45.7 +/- 3.0)% vs. (72. 6 +/- 5.0)%, P < 0.01] and the amplitude of caffeine-induced calcium transients [(16.0 +/- 3.5) FI vs. (43.5 +/- 6.2) FI, P < 0.01] were significantly decreased while its time to peak was significantly prolonged [(129.8 +/- 14.5) s vs. (52.2 +/- 7.4) s, P < 0.01] in HF rabbits. The RyR2 (0.106 +/- 0.007 vs. 0.203 +/- 0.021, P < 0.01) and the ratio of SERCA2a and NCX (1.22 +/- 0.23 vs. 1.96 +/- 0.12, P < 0.01) were also significantly reduced in myocytes of HF rabbits. Metoprolol significantly attenuated the decrease of EF [(60.2 +/- 5.1)%], the amplitude of calcium transient [(32.8 +/- 5.4) FI], the RyR2 expression (0.164 +/- 0.016) and the ratio of SERCA2a and NCX (1.68 +/- 0.17, all P < 0.05 vs. HF rabbits) and attenuated the increase of the time to peak of caffeine-induced calcium transients [(91.4 +/- 10.9) s, P < 0.05 vs. HF rabbits]. CONCLUSION: Metoprolol could improve the cardiac function possibly by preventing the alterations of calcium regulatory proteins and increasing calcium transients in failing heart.

[Effects of simvastatin on the left ventricular expression of transient outward potassium channel in rabbits with experimental heart failure].

OBJECTIVE: To investigate the effects of simvastatin on the left ventricular (LV) expression of transient outward potassium channel in rabbits with experimental heart failure (HF). METHODS: HF model was established by ligating the left anterior descending coronary artery of rabbits. Rabbits were randomized into simvastatin group (HF + S, 10 mg x kg(-1) x d(-1) for 10 weeks, n = 8), HF group (n = 9), and sham group (n = 9). Left ventricular remodeling and function were evaluated by echocardiography and hemodynamic measurements 10 weeks after operation. The mRNA and protein expressions of K(v)1.4, K(v)4.2 and K(v)4.3 potassium channel alpha subunit in LV were determined by semi-quantitative RT-PCR and Western blot. RESULTS: Simvastatin attenuated LV remodeling and improved cardiac function. The mRNA and protein expressions of K(v)1.4, K(v)4.2 and K(v)4.3 potassium channel alpha subunit in HF rabbits (0.48 +/- 0.09, 0.37 +/- 0.07, 0.42 +/- 0.11; 0.33 +/- 0.09, 0.22 +/- 0.07, 0.29 +/- 0.11) were significantly decreased compared with sham rabbits (0.85 +/- 0.08, 0.66 +/- 0.07, 0.67 +/- 0.08; 0.68 +/- 0.13, 0.53 +/- 0.15, 0.49 +/- 0.10, all P < 0.01), and these decreases could be attenuated by simvastatin (0.77 +/- 0.10, 0.50 +/- 0.10, 0.57 +/- 0.12; 0.58 +/- 0.10, 0.36 +/- 0.10, 0.43 +/- 0.12, all P < 0.01 vs. HF). CONCLUSION: Simvastatin not only attenuated LV remodeling and improved LV function but also prevented the downregulation of LV transient outward potassium channel expressions in rabbits with experimental HF.

Assessment of myocardial viability in patients with myocardial infarction using twenty-four hour thallium-201 late redistribution imaging.

BACKGROUND: Rest thallium-201 (201Tl) myocardial perfusion imaging has been widely used for evaluation of myocardial ischemia/viability after myocardial infarction, but the ideal timing for imaging after injection to maximally estimate viability is not well established. METHODS: Thirty-six patients with myocardial infarction underwent the initial, 3 h, and 24 h redistribution imaging after intravenous injection of 148-185 MBq 201Tl. The initial and 3 h images, the initial and 24 h images, and the 3 and 24 h images were compared double-blinded. RESULTS: Out of the 184 abnormal segments based on the initial imaging, 56 (30%) segments improved by at least 1 grade on the 3 h imaging while 78 (42%) segments improved by at least 1 grade on the 24 h imaging. The 24 h late imaging detected more viable myocardium than the 3 h imaging did, with a significant difference (chi2= 5.680, p = 0.017). There were 158 abnormal segments on the 3 h imaging, with average 28% (44) segments improved by at least 1 grade on the 24 h imaging. There were 128 initial abnormal segments with no improvement on the 3 h imaging. Out of these segments, the 24 h late redistribution imaging detected additional redistribution in 26 segments, taking up 20%. CONCLUSIONS: Twenty-four hour late 201Tl imaging will demonstrated additional redistribution in patients who have incompletely reversible defects on early redistribution imaging at 3h.

Twenty-four-hour thallium-201 late redistribution imaging enhances the detection of myocardial viability after myocardial infarction.

BACKGROUND: Thallium-201 (201Tl) myocardial perfusion imaging has been widely used for evaluation of myocardial ischemia/viability after myocardial infarction. The 3- to 4-h early redistribution imaging has underestimated a considerable part of viable myocardium, while the 24-h late redistribution imaging may enhance the detection of myocardial ischemia/viability, but remains controversial. METHODS: Thirty-eighty patients with myocardial infarction underwent the initial, 3-h, and 24-h redistribution imaging after intravenous injection of 148-185 MBq 201Tl. Image quality analysis was performed using a four-grade model: excellent, good, moderate, and poor. The initial and 3-h images, the initial and 24-h images, and the 3- and 24-h images were compared double-blinded. RESULTS: The 3- and 24-h images showed no significant differences in image quality according to the four-grade model (P=.3580). Out of the 194 abnormal segments based on the initial imaging, 60 (31%) segments improved by at least one grade on the 3-h imaging, while 86 (44%) segments improved by at least one grade on the 24-h imaging. The 24-h late imaging detected more viable myocardium than the 3-h imaging did, with a significant difference (chi2=7.4235, P=.0064). There were 164 abnormal segments on the 3-h imaging, with an average 30% (48) segments improved by at least one grade on the 24-h imaging. There were 134 initial abnormal segments without any improvement on the 3-h imaging. Out of these segments, the 24-h late redistribution imaging detected additional redistribution in 30 segments, taking up 22%. The mean global score on the 3-h imaging significantly decreased compared to that on the initial imaging (t=5.71, P<.0001), and the mean global score on the 24-h imaging further decreased significantly compared to that on the 3-h imaging (t=6.28, P<.0001). CONCLUSIONS: Twenty-four-hour late 201Tl imaging, with satisfactory image quality, enhances the detection of myocardial viability after myocardial infarction.

Low serum albumin levels in patients with paroxysmal atrial fibrillation: what does it mean?

BACKGROUND: Atrial fibrillation is the most common cardiac rhythm disturbance in clinical practice; its risk factors are complex and far from being clarified up to now. Previous studies demonstrated that hypoalbuminaemia significantly correlates with cardiac diseases. HYPOTHESIS: We hypothesized that the serum albumin levels were decreased in patients with paroxysmal atrial fibrillation (PAF) and that hypoalbuminaemia was a risk factor for PAF. METHODS: We selected retrospectively 32 consecutive PAF patients as experimental group and 32 strictly age- and sex-matched paroxysmal supraventricular tachycardia patients confirmed by electrophysiology as a normal control group. Serum albumin was assayed by the bromocresol green (BCG) method. The experimental group was compared with the control group using the paired sample t test for independent samples when dealing with approximately normally distributed variables and the Wilcoxon rank-sum test when appropriate. One sample t test was used to compare albumin levels of the control group with the normal population mean value established in this laboratory so as to eliminate the selection bias. The correlations between albumin levels and cardiac function classifications (NYHA) were assessed using Spearman's rho. Categorical variables were compared using chi-squared, Fisher's exact test or RxC contingency table. Logistic regression was used for analysis of risk factors of serum albumin levels and PAF. RESULTS: The baseline clinical characteristics between the 2 groups were comparable with no significant difference. In a univiariate analysis, albumin was significantly lower in patients with PAF (41.67 +/- 3.52 g/L) than in control patients (43.88 +/- 3.53 g/L, P = 0.009). The albumin levels among patients in the presence and the absence of baseline factors showed insignificant difference (P > 0.05). In a multivariable analysis of covariance that considered baseline factors, only PAF was an independent predictor of decreased albumin levels (P = 0.0454, OR = 0.375). Conversely, only hypoalbuminaemia was an independent predictor of PAF (P = 0.0129, OR = 0.773). CONCLUSIONS: PAF is associated with hypoalbuminaemia and hypoalbuminaemia is an independent risk factor for PAF patients. Although the cause and effect of hypoalbuminaemia and PAF remains to be clarified, the present study provides new information with respect to the aetiology and therapy of PAF patients.