Calcineurin and matrix protein expression in cardiac hypertrophy

In the compensatory state of human left ventricular hypertrophy (LVH), the remodeling processes in the extracellular matrix and the role of calcineurin (Cn) are not completely understood. The present work aimed to analyze the expression and activity of matrix metalloproteinases (MMPs), their endogenous inhibitors (TIMPs), and of Cn in patients with compensated LVH. By semiquantitative RT-PCR, Western blotting, and gelatine zymography, we determined mRNA, protein, and/or enzyme activity levels of MMPs, TIMPs, atrial natriuretic peptide (ANP), Cn subunits, and of the modulatory calcineurin-interacting protein (MCIP) 1. Myocardial samples from patients showing severe aortic stenosis, normal ejection fraction, and compensated LVH were compared with autopsy samples from healthy hearts. LVH patients showed upregulation of CnA-β mRNA but downregulation of both CnB-α mRNA and protein. Total Cn activity (as determined through NF-AT phosphorylation and MCIP1 mRNA expression) was unchanged. There were no differences in gene expression and activities of MMP-2, MMP-9, and of TIMPs 1–4 between LVH patients and controls. As expected, ANP mRNA expression was high in LVH patients. We propose a prominent role for CnB in controlling Cn activity in compensated LVH. At this stage of the disease, MMP and TIMP activities are balanced. Drs. Grammer and Bleiziffer contributed equally to the study Returned for 1st revision: 23 February 2006 1. revision received: 8 April 2006     

阿托伐他汀在心肌细胞肥大治疗中的作用

大量研究表明阿托伐他汀可干预心室重塑的形成和发展.应用阿托伐他汀能从不同途径发挥独特的心血管保护效应.本文从心肌细胞肥大这个角度阐述阿托伐他汀对心室重塑的影响.     

逆灸对不同运动强度小鼠心肌细胞的保护作用

目的:探讨逆灸对不同运动强度小鼠心肌细胞凋亡损伤的影响。方法:将60只昆明小鼠随机分为空白对照组、空白逆灸组、中等运动对照组、中等运动逆灸组、力竭运动对照组、力竭运动逆灸组,每组10只。采用不同运动强度对小鼠进行训练。各逆灸组取"足三里""关元"穴进行艾灸治疗,每穴每日灸5壮,每日1次,每周休息1d,共治疗3周。采用TUNEL法检测各组心肌细胞凋亡率,电镜观察各组心肌亚细胞结构破坏程度。结果:中等运动对照组与空白对照组相比,心肌细胞凋亡率升高(P0.05);中等运动逆灸组与中等运动对照组相比心肌细胞凋亡率下降(P0.05);力竭运动对照组与中等运动对照组相比,心肌细胞凋亡率升高(P0.05);力竭运动逆灸组与力竭运动对照组相比,心肌细胞凋亡率明显下降(P0.05)。电镜观察显示,中等运动逆灸组比中等运动对照组心肌细胞亚细胞结构破坏程度轻,力竭运动逆灸组比力竭运动对照组心肌细胞亚细胞结构破坏程度轻。结论:不同运动强度的运动训练均可引起心肌细胞发生凋亡损伤,且伴有心肌组织损伤,随着运动强度加大,心肌细胞发生凋亡更加明显;艾灸可减轻高强度运动对小鼠心肌细胞造成的损伤,减少细胞的凋亡。     

信号蛋白Smad3在大鼠心肌肥厚过程中的表达

目的研究信号蛋白Smad3在大鼠心肌肥厚中的表达变化。方法结扎大鼠腹主动脉复制心肌肥厚模型，在不同时间点检测左心室重量指数(LVMI)，RT—PCR法检测肥大心肌组织中TGF—β1、Smad3的mRNA表达，Western blotting以及免疫组化法检测Smad3蛋白的表达。结果术后3d LVMI开始上升并持续至28d，肥大心肌组织中TGF—β1、Smad3 mRNA及蛋白表达术后3d开始上升，持续至28d，术后14d为表达高峰。结论信号蛋白Smad3参与了腹主动脉结扎诱导的大鼠心肌肥厚病理过程。     

Renal hypertrophy in experimental diabetes: Relation to severity of diabetes

Summary Streptozotocin diabetic rats have larger kidneys than non-diabetic rats. In the present study the rate of kidney growth during the first seven days of diabetes was correlated with the blood glucose concentration. Over a wide range of blood glucose concentrations (116–340 mg/100 ml) the kidney weight, protein content and protein/DNA ratio were closely correlated with the glucose values.     

Pathophysiologic significance of left ventricular hypertrophy in dilated cardiomyopathy

Background and hypothesis: Patients with dilated cardiomyopathy (DCM) with left ventricular hypertrophy (LVH) have been found to have a better prognosis than patients without LVH. However, the pathophysiologic mechanism for that has not been investigated. We sought to clarify the pathophysiologic significance of LVH in DCM. Methods: We performed isoproterenol infusion echocar-diography (0.02 m?g/kg/min) in 17 patients with DCM, and measured plasma epinephrine and norepinephrine levels at rest and at the end of ergometer exercise in 14 of the 17 patients. Patients were classified into groups according to the presence (9 patients) (LVH+) or absence (8 patients) (LVH-) of LVH. Left ventricular hypertrophy was defined as an inter-ventricular thickness or posterior wall thickness ≥13 mm. Results: Although there was no significant difference between groups in fractional shortening at rest during isoproterenol infusion, fractional shortening was significantly higher in the LVH (+) group than in the LVH (-) group (29 ± 9 vs. 17 ± 8%;p<0.025). Although there was no significant difference in plasma norepinephrine level, it was significantly lower in the LVH (+) group than in the LVH (-) group (233 ± 169 vs. 519 ± 258 pg/ml;p<0.05) at the end point of the exercise. Conclusion: Systolic reserve, represented by the response to isoproterenol, is greater in patients with DCM with LVH than in those without LVH, and a lower plasma level of norepinephrine is needed to activate the myocardium during ex ercise in patients with DCM with LVH. This pathophysiologic characteristic could be one of the mechanisms which explain a better prognosis in patients with DCM with LVH.     

Increased 19 kDa protein phosphorylation and protein kinase C activity in pressure-overload cardiac hypertrophy

Summary The aim of the study was to determine the role of protein kinase C (PKC) in protein phosphorylation in hypertrophied C. myocytes, particularly the phosphorylation of the 19 kDa protein which corresponds to myosin light chains. In myocardial hypertrophy the PKC activity in the cytosolic fraction of tissue homogenate was increased up to 253 % of control hearts, and in membrane fraction up to 140 % of the control value. Phorbol ester (TPA), the specific activator of protein kinase C, stimulated phosphorylation of the 19 kDa protein obtained from isolated myocytes to 181 ± 9 % of control value in normal and to 248 ± 66 % in hypertrophic myocytes. Taken together, these data suggest that protein kinase C might be involved in the increased phosphorylation of cardiac myosin light chain protein in myocardial hypertrophy.     

Identification of Candidate Long Noncoding RNAs Associated with Left Ventricular Hypertrophy

Purpose

Long noncoding RNAs (lncRNAs) constitute an emerging group of noncoding RNAs, which regulate gene expression. Their role in cardiac disease is poorly known. Here, we investigated the association between lncRNAs and left ventricular hypertrophy.

Methods

Wild‐type and adenosine A2A receptor overexpressing mice (A2A‐Tg) were subjected to transverse aortic constriction (TAC) and expression of lncRNAs in the heart was investigated using genome‐wide microarrays and an analytical pipeline specifically developed for lncRNAs.

Results

Microarray analysis identified two lncRNAs up‐regulated and three down‐regulated in the hearts of A2A‐Tg mice subjected to TAC. Quantitative PCR showed that lncRNAs 2900055J20Rik and Gm14005 were decreased in A2A‐Tg mice (3.5‐ and 1.8‐fold, p < 0.01). We found from public microarray dataset that 2900055J20Rik and Gm14005 were increased in TAC mice compared to sham‐operated animals (1.8‐ and 1.4‐fold, after 28 days, p < 0.01). Interestingly, in this public dataset, cardioprotective drug JQ1 decreased 2900055J20Rik and Gm14005 expression by 2.2‐ and 1.6‐fold (p < 0.01).

Conclusions

First, we have shown that data on lncRNAs can be obtained from gene expression microarrays. Second, expression of lncRNAs 2900055J20Rik and Gm14005 is regulated after TAC and can be modulated by cardioprotective molecules. These observations motivate further investigation of the therapeutic value of lncRNAs in the heart.     

Recapitulating endochondral ossification: a promising route to in vivo bone regeneration

Despite its natural healing potential, bone is unable to regenerate sufficient tissue within critical‐sized defects, resulting in a non‐union of bone ends. As a consequence, interventions are required to replace missing, damaged or diseased bone. Bone grafts have been widely employed for the repair of such critical‐sized defects. However, the well‐documented drawbacks associated with autografts, allografts and xenografts have motivated the development of alternative treatment options. Traditional tissue engineering strategies have typically attempted to direct in vitro bone‐like matrix formation within scaffolds prior to implantation into bone defects, mimicking the embryological process of intramembranous ossification (IMO). Tissue‐engineered constructs developed using this approach often fail once implanted, due to poor perfusion, leading to avascular necrosis and core degradation. As a result of such drawbacks, an alternative tissue engineering strategy, based on endochondral ossification (ECO), has begun to emerge, involving the use of in vitro tissue‐engineered cartilage as a transient biomimetic template to facilitate bone formation within large defects. This is driven by the hypothesis that hypertrophic chondrocytes can secrete angiogenic and osteogenic factors, which play pivotal roles in both the vascularization of constructs in vivo and the deposition of a mineralized extracellular matrix, with resulting bone deposition. In this context, this review focuses on current strategies taken to recapitulate ECO, using a range of distinct cells, biomaterials and biochemical stimuli, in order to facilitate in vivo bone formation. Copyright © 2014 John Wiley & Sons, Ltd.