Distribution of collagens and fibronectin in the subepicardium during avian cardiac development

Summary The development of the layer of connective tissue between ventricular epicardium and myocardium was studied during chick morphogenesis using electron microscopy, light microscopy and immunohistochemical techniques. This layer, called the subepicardium, increases rapidly in volume from embryonic day 6 to 11 (E6–E11) during mesenchymal cell invasion. Fibrous, matrix components are initially apparent at E11 to E16, and as fibrous connective tissue structures accumulate, subepicardial volume decreases. Antibody labeling shows that fibronectin is an early, prominent constituent of the subepicardium, and by E8, the subepicardium is the cardiac site most enriched in fibronectin. Collagen type III is present in circumferentially-oriented fibers at E8. During subsequent cardiac growth, collagen type III fibers become broadly distributed in the subepicardium, with some fibers appearing to attach myocardium to epicardium. Collagen type I fibers are not apparent until E10. At E12 collagen type I fibers are distributed circumferentially around the heart in bundles crimped into waves of low amplitude. Other collagen type I fibers are oriented radially in the subepicardium. During late cardiac morphogenesis and in fully-differentiated hearts, fibronectin and collagen types I and III are more concentrated in the subepicardium than within the myocardium. These observations suggest that the composition and organization of the subepicardial connective tissue may make important contributions to cardiac mechanics from the latter half of embryonic development through adulthood.     

Reversible Secretion of Glycosaminoglycans and Proteoglycans by Cyclically Stretched Valvular Cells in 3D Culture

Mitral valve leaflets and chordae have been shown to contain different amounts and proportions of glycosaminoglycans (GAGs) and proteoglycans (PGs) corresponding to in vivo normal or diseased cyclic strain patterns. To understand the effect of cyclic strains on GAG/PG synthesis by valvular interstitial cells (VICs) isolated from valve leaflet and chordae separately, porcine VICs were seeded within collagen gels and alternately stretched or relaxed for 24 h periods for one week in a custom-designed tissue engineering bioreactor. We found cyclic-stretch-induced upregulation of total GAGs and of individual GAG classes secreted into the culture medium. Leaflet cells showed a delayed response to stretching compared to chordal cells, but altered the proportions of various GAG classes they secreted during the culture duration. Decorin and biglycan PGs were slightly responsive to stretch. We demonstrated that mechanical stretch and relaxation conditions reversibly regulate GAG and PG production in a novel 3D model of valve tissues. This is the first study using cyclic strains to modulate GAG/PG synthesis by valve cells and our results may have implications for the remodeling of the mitral valve as well as other tissues.     

血清CA125水平在心力衰竭患者心功能分级中的应用价值

目的 探讨血清CA125(糖类抗原125)与BNP(B型脑利钠肽)水平在心力衰竭患者心功能分级中的变化及其临床意义.方法 收集118例我院2011年1月至2011年12月住院且诊断为心力衰竭患者数据进行回顾性统计学分析.结果 与健康对照组比较,NYHA Ⅱ(纽约心脏病协会心功能分级)、NYHA Ⅲ、NYHA ⅣV、心血管疾病无合并心力衰竭组四组血清CA125、BNP水平均显著高于健康对照组(P＜0.01),且血清CA125与BNP水平升高与NYHA分级呈正相关.不同病因(冠心病、风湿性心脏病、高血压性心脏病、扩张型心肌病、心脏瓣膜疾病)组血清CA125、BNP水平两两比较扩张型心肌病组血清CA125水平显著高于高血压性心脏病组(P＜0.05),而BNP水平在不同病因组中无统计学差异.左心室扩大组血清CA125水平显著高于正常左心室组(P＜0.01);而LVEF水平显著低于正常左心室组(P＜0.01).NYHA分级有胸腔积液、心包积液、房颤组血清CA125水平均高于无上述体征组,且差异具有统计学意义(P＜0.01).血清CA125与BNP呈显著正相关(P＜0.01);血清CA125与LVEF(左室射血分数)呈显著负相关(P＜0.01).结论 结合血清CA125、BNP、LVEF等指标可判断HF严重程度,并为NYHA分级提供实验室辅助依据.血清CA125、BNP、LVEF等指标作为临床实验室指标,综合病因、症状、体征和其他非创伤性指标可有效监控HF的发生与发展.     

Activation of signaling molecules and matrix metalloproteinases in right ventricular myocardium of rats with pulmonary hypertension

Pulmonary hypertension induces right ventricular (RV) overload, which is transmitted to cardiomyocytes via integrins that activate intracellular messengers, including focal adhesion kinase (FAK) and neuronal nitric oxide synthase (NOS1). We investigated whether RV hypertrophy (RVH) and RV failure (RVF) were associated with activation of FAK, NOS1, and matrix metalloproteinases (MMPs).

Rats were treated without (RVC) or with a low dose of monocrotaline (30 mg/kg) to induce RVH, and with a high dose (80 mg/kg) to induce RVF. After ≈30 days, RV function was determined using a combined pressure-conductance catheter. After sacrifice, FAK, NOS1, their phosphorylated forms (FAK-P and NOS1-P), MMP-2, and MMP-9 were quantified in RV myocardium by immunohistochemistry.

In RVH and RVF, RV weight/ body weight increased by 36% and 109%, whereas RV ejection fraction decreased by 23% and 57% compared to RVC, respectively. FAK-P and FAK-P/FAK were highest in RVH (2.87±0.12 and 2.52±0.23 fold compared to RVC, respectively) and slightly elevated in RVF (1.76±0.17 and 1.15±0.13 fold compared to RVC, respectively). NOS1-P and NOS1-P/NOS1 were increased in RVH (1.63±0.12 and 3.06±0.80 fold compared to RVC, respectively) and RVF (2.16±0.03 and 3.30±0.38 fold compared to RVC, respectively). MMP-2 was highest in RVH and intermediate in RVF (3.50±0.12 and 1.84±0.22 fold compared to RVC, respectively). MMP-9 was elevated in RVH and RVF (2.39±0.35 and 2.92±0.68 fold compared to RVC, respectively).

Activation of FAK in RVH points to an integrin-dependent hypertrophic response of the myocardium. Activation of NOS1 in failing RV suggests a role of excessive NO in the development of failure and activation of MMPs leading to ventricular remodeling.     

The Local Matrix Distribution and the Functional Development of Tissue Engineered Cartilage,a Finite Element Study

Assessment of the functionality of tissue engineered cartilage constructs is hampered by the lack of correlation between global measurements of extra cellular matrix constituents and the global mechanical properties. Based on patterns of matrix deposition around individual cells, it has been hypothesized previously, that mechanical functionality arises when contact occurs between zones of matrix associated with individual cells. The objective of this study is to determine whether the local distribution of newly synthesized extracellular matrix components contributes to the evolution of the mechanical properties of tissue engineered cartilage constructs. A computational homogenization approach was adopted, based on the concept of a periodic representative volume element. Local transport and immobilization of newly synthesized matrix components were described. Mechanical properties were taken dependent on the local matrix concentration and subsequently the global aggregate modulus and hydraulic permeability were derived. The transport parameters were varied to assess the effect of the evolving matrix distribution during culture. The results indicate that the overall stiffness and permeability are to a large extent insensitive to differences in local matrix distribution. This emphasizes the need for caution in the visual interpretation of tissue functionality from histology and underlines the importance of complementary measurements of the matrixs intrinsic molecular organization.     

Right ventricular expression of extracellular matrix proteins, matrix-metalloproteinases, and their inhibitors over a period of 3 years after heart transplantation

Fibrillar collagens I and III, nonfibrillar collagen IV, and the glycoproteins fibronectin and laminin, are elements of the myocardial extracellular matrix (ECM). Alterations in the normal concentrations and ratios of these elements may reflect remodeling in response to physiologic stress. In the case of patients' post-heart transplantation (HTx), specific patterns of alteration may herald myocardial dysfunction. Right ventricular biopsies were taken from the same 28 HTx patients before implantation and 1 week, 2 weeks, and 1, 2, and 3 years after HTx. The above-noted five ECM proteins, six matrix metalloproteinases (MMPs) and two of their tissue inhibitors (TIMPs) were detected by immunohistochemistry and scored as cells per square millimeter or semiquantitatively. The total connective tissue fibers were detected by connective tissue stain and morphometry. Variations in these ECM components were followed in the same patient cohort over 3 years. In summary, during the first 2 weeks after HTx, a predominant increase in connective tissue occurred. Increases in MMP-8 and MMP-9 were found. By 3 years after transplantation, there was a decrease of connective tissue fibers and a significant reduction of all ECM components and an increase in MMPs and TIMPs. These findings may reflect a pattern of remodeling specific to the transplanted heart.     

Measuring Regional Changes in the Diastolic Deformation of the Left Ventricle of SHR Rats Using microPET Technology and Hyperelastic Warping

The objective of this research was to assess applicability of a technique known as hyperelastic warping for the measurement of local strains in the left ventricle (LV) directly from microPET image data sets. The technique uses differences in image intensities between template (reference) and target (loaded) image data sets to generate a body force that deforms a finite element (FE) representation of the template so that it registers with the target images. For validation, the template image was defined as the end-systolic microPET image data set from a Wistar Kyoto (WKY) rat. The target image was created by mapping the template image using the deformation results obtained from a FE model of diastolic filling. Regression analysis revealed highly significant correlations between the simulated forward FE solution and image derived warping predictions for fiber stretch (R ² = 0.96), circumferential strain (R ² = 0.96), radial strain (R ² = 0.93), and longitudinal strain (R ² = 0.76) (p < 0.001 for all cases). The technology was applied to microPET image data of two spontaneously hypertensive rats (SHR) and a WKY control. Regional analysis revealed that, the lateral freewall in the SHR subjects showed the greatest deformation compared with the other wall segments. This work indicates that warping can accurately predict the strain distributions during diastole from the analysis of microPET data sets.     

Enhanced aggregation of β-amyloid-containing peptides by extracellular matrix and their degradation by the 68 kDa serine protease prepared from human brain

To explore whether extracellular matrix components in human brain affect the deposition and aggregation of β-amyloid containing peptides, human brain samples from patients with sporadic Alzheimer's disease and normal aged were analyzed by Western blot analysis. All major β-amyloid-containing peptides contained epitope(s) which is recognized by anti heparan sulfate antibody. Incubation of brain β-amyloid-containing peptides with human collagen type IV in neutral pH efficiently generated a high molecular weight aggregated band, approximately 5-fold that of the control sample. We have previously found a serine protease which is capable of cleaving an oligopeptide at the N-terminus of β-amyloid. In this study, the protease, which also contains heparan sulfate glycoconjugates, degraded the above brain peptides as natural substrates, although with different efficiency. These findings suggest that extracellular matrix components affect the processing and aggregation of β-amyloid-containing peptides in human brain.     

高血压和合并动脉粥样硬化患者血小板分布宽度、血糖血脂水平变化及其危险因素分析

目的:回顾性比较高血压和合并动脉粥样硬化(AS)患者中血小板、血糖、血脂、血尿酸等指标的水平变化,分析高血压及合并AS的危险因子.方法:选取2019-06—2019-08在本院体检人群资料,按照检查结论分为高血压组(n=44)、高血压+AS组(n=73)和非高血压及AS对照组(n=91),采用临床检验科常规方法分别检测...