Yang Ss

Nitric oxide overproduction derived from inducible nitric oxide synthase increases cardiomyocyte apoptosis in human atrial fibrillation

BACKGROUND Inflammation and oxidant stress have been suggested to be involved in the structural remodeling in atrial fibrillation (AF), and inducible nitric oxide synthase (iNOS) is associated with inflammation and oxidant stress. To study whether iNOS could contribute to atrial remodeling in AF, we investigated the relationship between inflammation, oxidant stress, nitric oxide (NO) and its synthase, and cardiomyocytic apoptosis in the right atrium in human AF. METHODS Fifteen patients with permanent AF (PmAF) and 17 patients with sinus rhythm (SR), who underwent mitral valve replacement surgery were investigated. Western blotting and immunohistochemical staining were used to detect the expression of endothelial nitric oxide synthase (eNOS), iNOS and 3-nitrotyrosine (3NT; a biological marker of peroxynitrite) in the right atrium. The occurrence of cardiomyocytic apoptosis was determined by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL). Caspase 3 staining for the activated, cleaved protease was also performed. In addition, concentrations of NO(2)(-)/NO(3)(-) (NO(X)) both in plasma and in the right atrium were measured by a NO(X) Detection Kit. Finally, plasma levels of high-sensitivity C-reactive protein (hs-CRP) were routinely measured. RESULTS AND CONCLUSIONS Levels of hs-CRP were far more enhanced in patients with PmAF compared to the controls. Plasma levels of NO(X) were significantly lower in PmAF patients than SR patients, but the production of NO(X) in the local right atrium increased obviously. Furthermore, iNOS and 3NT expressions increased dramatically in the right atrium in PmAF patients, whereas the expression of eNOS did not change apparently. In addition, when patients were further divided into a higher hs-CRP group (> or =5 mg/L) and a lower hs-CRP group (<5 mg/L) according to the hs-CRP level, significant upregulation of iNOS was found in the higher hs-CRP group. Apoptosis index and caspase 3 staining were also prominently enhanced in PmAF patients compared with SR patients. More importantly, we demonstrated in this study that a higher expression of 3NT was associated with an increased expression of iNOS/eNOS (r=0.74, P<0.05) and an enhanced apoptosis index (r=0.69, P<0.05). In conclusion, the results presented novel evidence that imbalanced expression of iNOS/eNOS could contribute to protein nitration and cardiomyocyte apoptosis in human AF, in which condition inflammation may be an important participant.

Association of HLA class II DRB1, DPA1 and DPB1 polymorphism with genetic susceptibility to idiopathic dilated cardiomyopathy in Chinese Han nationality

Although the aetiology of idiopathic dilated cardiomyopathy (IDC) remains unclear, many immunological abnormalities involving changes in cell-mediated and humoral immunity may be associated with cardiac impairment in IDC. Autoimmune mechanisms are likely to participate in the pathogenesis of at least a subgroup of IDC and components of the major histocompatibility complex may serve as markers for the propensity to develop immune-mediated myocardial damage. Human leukocyte antigen (HLA) class II genes, which are highly polymorphic, play an important role in the activating of immune responses and thus control the predisposition for or protection from IDC. This study explores the possible contribution of HLA-DRB and DP polymorphisms to IDC susceptibility. DNA genotyping for HLA-DRB1, DPA1 and DPB1 was performed using polymerase chain reaction-sequencing based typing (PCR-SBT) method in 198 IDC patients and 136 random selected healthy Han ethnic individuals living in Northern China. IDC patients were, sub-grouped into asymptomatics (subgroup A), with arrhythmia (subgroup B) and with overt congestive heart failure (subgroup C) according to the clinical manifestations and electrocardiogram or echocardiographic characteristics. ADP/ATP autoantibody was detected in IDC group by immunoblot analysis. The results revealed that HLA-DR15, -DPB*0601 frequencies were significantly elevated in IDC group compared with normal control. The DPB1*0601 allele in homozygous form or in combination with allele DPB1*2301 or *3901, was found present more often in IDC patients. The predominance of HLA-DR4 allele was observed in subgroup B after stratification. However, the frequency of DPB1*0101 allele increased in the control than in the IDC group. The frequency of HLA-DPB1*0601 allele was significantly higher in IDC patients with positive autoantibody against ADP/ATP carrier of myocardial mitochondria in contrast to those with negative autoantibody. We conclude that HLA-DR4, -DR15, -DPB1*0601 alleles confers susceptibility to, while DPB1*0101 allele confers protection from IDC among individuals of northern Chinese Han nationality. The glutamate at position 69 in the second exon of DPB1*0601, as a key residue for special conformation of HLA-DP, may confer predisposition to IDC. HLA-DR and -DP alleles polymorphisms may serve as genetic markers for IDC and be involved in the regulation of the immune specific response to auto or exterior anti-myocardium antibodies.

Comparison of cardioprotective efficacy resulting from a combination of atorvastatin and ischaemic post‐conditioning in diabetic and non‐diabetic rats

The aim of the present study was to investigate whether the combination of acute or chronic atorvastatin treatment with ischaemic post‐conditioning (IPost) exerts differential effects within the hearts of diabetic and non‐diabetic rats. Diabetic and non‐diabetic rats were randomly assigned to one of six groups: (i) a non‐conditioned group; (ii) a group subjected to IPost; (iii) acute statin treatment (50 μmol/L atorvastatin during reperfusion) without IPost; (iv) acute statin treatment plus IPost; (v) chronic statin treatment (10 mg/kg atorvastatin per day for 2 weeks) without IPost; and (vi) chronic statin treatment plus IPost. The hearts from rats in each group were subjected to 30 min global ischaemia, followed by 120 min reperfusion. Infarct size, haemodynamics and Akt and endothelial nitric oxide synthase (eNOS) expression were examined. In hearts from diabetic rats, IPost did not limit infarct size or recover contractile dysfunction. Acute atorvastatin treatment with IPost limited infarct size and recovered contractile dysfunction in hearts from both diabetic and non‐diabetic rats and further activated Akt and eNOS signalling pathways to enhance these protective effects in hearts from diabetic rats. Chronic statin treatment with IPost neither reduced infarct size nor increased recovery of myocardial dysfunction in hearts from both diabetic and non‐diabetic rats; this may be associated with inhibition of Akt and eNOS phosphorylation. The combination of acute atorvastatin treatment with IPost had a greater protective effect within hearts from diabetic rats, but chronic statin treatment with IPost failed to protect against reperfusion injury in hearts from either diabetic or non‐diabetic rats. These findings will be important for the design of future clinical investigations.

Matrine improved the function of heart failure in rats via inhibiting apoptosis and blocking β3‑adrenoreceptor/endothelial nitric oxide synthase pathway.

Matrine, an alkaloid isolated from the traditional Chinese medicine Sophora flavescens AIT has exhibited a number of therapeutic effects on cardiovascular and liver diseases. The purpose of the present study was to investigate whether matrine has a protective effect on heart failure in rats. Coronary artery ligation was used to induce a heart failure (CHF) model in rats. Four weeks following the procedure, the rats were treated with different doses of matrine for one month. Histopathological examination demonstrated that matrine treatment alleviated myocardial hypertrophy and cardiac fibrosis in failing hearts. Furthermore, matrine administration also inhibited the increase of plasma aspartate amino transferase, creatine phosphokinase and lactate dehydrogenase levels in CHF rats. The rats with heart failure exhibited a significant reduction in ejection fraction and fractional shortening, as well as an increase in the left ventricular end systolic dimension, and matrine attenuated this decline in heart function. Further investigation demonstrated that matrine treatment also inhibited the upregulation of Bax and increase in the Bcl‑2 expression in the failing hearts. Furthermore, the upregulation of β3-adrenoreceptor (AR) and endothelial nitric oxide synthase proteins following heart failure were also attenuated by matrine. In conclusion, matrine had a preventive role in heart failure in rats at least in part by inhibiting myocardial apoptosis and the β3-AR pathway.

Mechanisms mediating the cardioprotective effects of rapamycin in ischaemia–reperfusion injury

1. In the present study, the temporal and concentration‐dependent cardioprotective effects of rapamycin against ischaemia–reperfusion (I/R) injury, as well as the underlying mechanisms, were investigated.

Effects of Acute and Chronic Atorvastatin on Cardioprotection of Ischemic Postconditioning in Isolated Rat Hearts

BACKGROUND Myocardial reperfusion therapy remains the most effective strategy to limit infarct size and improve clinical outcome. However, reperfusion injury is still inevitable, and a number of strategies have been developed to ameliorate its lethal outcome. The beneficial roles of ischemic postconditioning (Ipost) have regained more interest in targeting myocardial reperfusion phase to improve cardioprotection. AIMS This study was to determine whether acute or chronic treatment with atorvastatin affects cardioprotection when it was combined with Ipost. RESULTS Acute or chronic atorvastatin treatment significantly reduced infarct size and recovered contractile dysfunction during reperfusion. When Ipost was combined with atorvastatin treatment, chronic, but not acute, atorvastatin therapy attenuated the cardioprotective effects of Ipost. Chronic, but not acute, atorvastatin treatment also abolished Ipost-induced phosphorylation level of Akt and endothelial nitric oxide synthase (eNOS). CONCLUSIONS Chronic atorvastatin treatment could interfere with cardioprotective effects of Ipost on limiting infarct size and contractile dysfunction, possibly via inhibition of Akt and eNOS activity. This study suggests that Ipost should be used carefully when atorvastatin is taken by patients with AMI.

Effects of Hydrocortisone on the Differentiation of Human T Helper 2 Cells

We investigated the effects of the neuroendocrine modulator hydrocortisone (HC) on Th2 differentiation of human naive CD4+ T cells with and without CD28 co‐stimulation. Human naive CD4+ T cells were isolated and purified from umbilical cord blood mononuclear cells from full‐term newborn infants. CD4+ T cells were treated with different concentrations of HC under Th0 or Th2 culture conditions. Th0 conditions included stimulation by immobilized monoclonal antibodies (mAbs) against CD3 and CD28; Th2 conditions were the same + rhIL‐4. Parallel cultures excluded the CD28 mAb. Th1 (IL‐2, INF‐γ)‐ and Th2 (IL‐4, IL‐5)‐type cytokines were quantified in culture supernatants by ELISA and within cells by flow cytometry. For both Th0 and Th2 culture conditions, HC significantly inhibited Th1 cytokines’ release (IL‐2 and INF‐γ). For Th0 culture conditions, HC slightly increased IL‐4 expression (Th2 cytokine). However, for Th2 culture conditions, HC inhibited the IL4‐induced production of IL‐4. Although the absolute cytokine amounts were decreased, absence of CD28 co‐stimulation did not alter these ‘trends’. Our findings indicate that HC can alter the Th1/Th2 balance by inhibiting the production of Th1‐type cytokines. HC can also diminish the extensive Th2 differentiation induced by IL‐4.

Protective Effects of Isorhynchophylline on Cardiac Arrhythmias in Rats and Guinea Pigs

As one important constituent extracted from a traditional Chinese medicine, Uncaria Rhynchophylla Miq Jacks, isorhynchophylline has been used to treat hypertension, epilepsy, headache, and other illnesses. Whether isorhynchophylline protects hearts against cardiac arrhythmias is still incompletely investigated. This study was therefore aimed to examine the preventive effects of isorhynchophylline on heart arrhythmias in guinea pigs and rats and then explore their electrophysiological mechanisms. In vivo, ouabain and calcium chloride were used to establish experimental arrhythmic models in guinea pigs and rats. In vitro, the whole-cell patch-lamp technique was used to study the effect of isorhynchophylline on action potential duration and calcium channels in acutely isolated guinea pig and rat cardiomyocytes. The dose of ouabain required to induce cardiac arrhythmias was much larger in guinea pigs administered with isorhynchophylline. Additionally, the onset time of cardiac arrhythmias induced by calcium chloride was prolonged, and the duration was shortened in rats pretreated with isorhynchophylline. The further study showed that isorhynchophylline could significantly decrease action potential duration and inhibit calcium currents in isolated guinea pig and rat cardiomyocytes in a dose-dependent manner. In summary, isorhynchophylline played a remarkably preventive role in cardiac arrhythmias through the inhibition of calcium currents in rats and guinea pigs.

Effects of Thoracic Epidural Anesthesia on Cardiac Function and Myocardial Cell Apoptosis in Isoproterenol‐Induced Chronic Heart Failure Rats

OBJECTIVE This study aimed to investigate the effects of thoracic epidural anesthesia (TEA) on cardiac function and myocardial cell apoptosis in isoproterenol (ISO) induced chronic heart failure (CHF) rats. METHOD Rats were classified into 4 groups: the healthy control, ISO-induced CHF, ISO + TEA, and sham-treated groups. After 4 weeks, the animals in each group were examined by echocardiography. Invasive hemodynamic measurements were also preformed. RESULTS Echocardiographic findings suggested that rats in the ISO + TEA group exhibited decreased left ventricular end-systolic (LVES) and left ventricular end-diastolic (LVED), and increased left ventricular ejection fraction (LVEF) and left ventricular shortening fraction (LVFS) compared with rats in the ISO-induced CHF group. Rats in the ISO + TEA group showed improved left ventricular systolic pressure (LVSP) and left ventricular end-diastolic pressure (LVEDP) compared with rats in the ISO-induced CHF group. Additionally, rats in the ISO + TEA group had significant decrease in LV and RV mass indexes (LVMI and RVMI) compared with rats in the ISO-induced CHF rats. Myocardial ultrastructure in the ISO + TEA group significantly improved compared with the ISO-induced CHF group. TEA significantly reduced the percent of TUNEL-positive cells in the ISO + TEA group compared with the ISO-induced CHF group. Compared with the ISO-induced CHF group, Bcl-2 expression of rats in the ISO + TEA group was significantly increased, while Bax expression was significantly attenuated. CONCLUSION Our findings suggest that TEA may reduce myocardial apoptosis and decrease extent of structural damage and abnormalities in the myocardium.

Molecular Characterization of the Porcine TIM‐3 Gene

TIM‐3 is a member of the TIM (T‐cell immunoglobulin domain and mucin domain) family, which plays an important role in TH1 responses and autoimmune diseases. In this study, we cloned and characterized the porcine TIM‐3 gene. Real‐time PCR showed little expression of porcine TIM‐3 in muscle and stomach, low expression in kidney, brain, stomach and muscle, moderate expression in liver, small intestine and lymph, and high expression in spleen and lung. Transient transfection indicated that porcine TIM‐3 fusion protein was found to localize on the cell membranes or cytoplasm. Association analysis indicated that the SNP AccI in exon2 was significantly associated (P < 0.05) with red blood cell count mean corpuscular haemoglobin, packed cell volume, Lymphocyte percentage and Lymphocyte modulus. In conclusion, our results provide some information for conducting further studies on the functions of porcine TIM‐3 gene in type I diabetes and suggest that SNP AccI in exon2 may be utilized as a marker for molecular‐assisted selection in animal breeding.