Functional Effects of a Restrictive-Cardiomyopathy-Linked Cardiac Troponin I Mutation (R145W) in Transgenic Mice

The human cardiac troponin I (hcTnI) mutation R145W has been associated with restrictive cardiomyopathy. In this study, simultaneous measurements of ATPase activity and force in skinned papillary fibers from hcTnI R145W transgenic mice (Tg-R145W) were explored. Tg-R145W fibers showed an ∼ 13-16% increase in maximal Ca²⁺-activated force and ATPase activity compared to hcTnI wild-type transgenic mice. The force-generating cross-bridge turnover rate (g) and the energy cost (ATPase/force) were the same in all groups of fibers. Also, the Tg-R145W fibers showed a large increase in the Ca²⁺ sensitivity of both force development and ATPase. In intact fibers, the mutation caused prolonged force and intracellular [Ca²⁺] transients and increased time to peak force. Analysis of force and Ca²⁺ transients showed that there was a 40% increase in peak force in Tg-R145W muscles, which was likely due to the increased Ca²⁺ transient duration. The above cited results suggest that: (1) there would be an increase in resistance to ventricular filling during diastole resulting from the prolonged force and Ca²⁺ transients that would result in a decrease in ventricular filling (diastolic dysfunction); and (2) there would be a large (approximately 53%) increase in force during systole, which may help to partly compensate for diastolic dysfunction. These functional results help to explain the mechanisms by which these mutations give rise to a restrictive phenotype.     

Personalized Computer Simulation of Diastolic Function in Heart Failure

The search for a parameter representing left ventricular relaxation from non-invasive and invasive diagnostic tools has been extensive, since heart failure (HF) with preserved ejection fraction (HF-pEF) is a global health problem. We explore here the feasibility using patient-specific cardiac computer modeling to capture diastolic parameters in patients suffering from different degrees of systolic HF. Fifty eight patients with idiopathic dilated cardiomyopathy have undergone thorough clinical evaluation, including cardiac magnetic resonance imaging (MRI), heart catheterization, echocardiography, and cardiac biomarker assessment. A previously-introduced framework for creating multi-scale patient-specific cardiac models has been applied on all these patients. Novel parameters, such as global stiffness factor and maximum left ventricular active stress, representing cardiac active and passive tissue properties have been computed for all patients. Invasive pressure measurements from heart catheterization were then used to evaluate ventricular relaxation using the time constant of isovolumic relaxation Tau (s). Parameters from heart catheterization and the multi-scale model have been evaluated and compared to patient clinical presentation. The model parameter global stiffness factor, representing diastolic passive tissue properties, is correlated signif-icantly across the patient population with s. This study shows that multi-modal cardiac models can successfully capture diastolic (dys) function, a prerequisite for future clinical trials on HF-pEF.     

Regulation of fermentative capacity and levels of glycolytic enzymes in chemostat cultures of Saccharomyces cerevisiae

Regulation of fermentative capacity was studied in chemostat cultures of two Saccharomyces cerevisiae strains: the laboratory strain CEN.PK113-7D and the industrial bakers’ yeast strain DS28911. The two strains were cultivated at a fixed dilution rate of 0.10 h⁻¹ under various nutrient limitation regimes: aerobic and anaerobic glucose limitation, aerobic and anaerobic nitrogen limitation on glucose, and aerobic ethanol limitation. Also the effect of specific growth rate on fermentative capacity was compared in glucose-limited, aerobic cultures grown at dilution rates between 0.05 h⁻¹ and 0.40 h⁻¹. Biomass yields and metabolite formation patterns were identical for the two strains under all cultivation conditions tested. However, the way in which environmental conditions affected fermentative capacity (assayed off-line as ethanol production rate under anaerobic conditions) differed for the two strains. A different regulation of fermentative capacity in the two strains was also evident from the levels of the glycolytic enzymes, as determined by in vitro enzyme assays. With the exception of phosphofructokinase and pyruvate decarboxylase in the industrial strain, no clear-cut correlation between the activities of glycolytic enzymes and the fermentative capacity was found. These results emphasise the need for controlled cultivation conditions in studies on metabolic regulation in S. cerevisiae and demonstrate that conclusions from physiological studies cannot necessarily be extrapolated from one S. cerevisiae strain to the other.     

肥厚型心肌病患者在心肺运动中核心指标的特征性研究*

目的: 肥厚型心肌病（HCM）,以心肌肥厚为主要特征的心肌疾病,猝死率高。临床症状表现为呼吸困难、乏力、胸痛等。症状限制性极限运动心肺运动试验（CPET）在整体整合生理和医学（HIPM）理论指导下是唯一评估人体整体功能状态检查,肥厚型心肌病患者在心肺运动中核心数据变化值得进一步探讨。方法: 选择2017年4月至2020年1月在阜外医院就诊签署知情同意书后完成CPET受试者244例为研究对象,其中219例肥厚型心肌病（肥厚心组）和无诊断疾病健康人25例（正常组）,观察两组CPET核心指标的异同。结果: ①肥厚心组男163女56例,正常组11男14女;肥厚心组年龄（46.7±12.8,16.0~71.0）岁;正常组年龄（43.7±10.4,26.0~61.0）岁。②肥厚心组CPET核心指标的峰值摄氧量（Peak VO₂）为（65.2±13.8,22.8~103.4）%pred;无氧阈（AT）为（66.4±13.0,33.7~103.5）%pred;峰值氧脉搏（Peak O₂ pulse）为（84.3±19.0,90.9~126.0）%pred;摄氧效率平台（OUEP）为（99.2±13.4,69.1~155.5）%pred;分钟通气量和二氧化碳排出量比值最小值（Lowest VE/VCO₂）为（108.0±13.2,70.4~154.0）%pred;分钟通气量和二氧化碳排出量比值斜率（VE/VCO₂ Slope）为（108.5±17.9,66.9~164.9）%pred, 肥厚心组较正常组在峰值摄氧量,无氧阈,峰值氧脉搏,摄氧效率平台等百分预计值（%pred）等指标均显著降低（P<0.01或P<0.05）;而Lowest VE/VCO₂和VE/VCO₂ Slope（%pred）显著升高（P<0.05）,差异均有统计学意义。个体而言,部分患者就诊时整体功能状态尚在正常范围内。③CPET中Peak VO₂与其他核心指标AT、OUEP、Peak O₂ pulse、峰值收缩压呈正相关;与Lowest VE/VCO₂ 和VE/VCO₂ Slope呈负相关。结论: 肥厚型心肌病患者能安全完成CPET,CPET指标具有特异性,不仅可用于整体功能评测、疾病诊断与鉴别诊断、危险分层、疗效评估和精准预后预测,并可用于整体论指导下的个体化整体方案慢病有效管理,值得进一步深入研究和临床推广应用。     

克山病是一种“心肌线粒体病(Mitochondrial Cardiomyopathy)”

亚急克病人心肌线粒体内膜电子传递链的琥珀酸氧化酶系,琥珀酸脱氢酶和细胞色素氧化酶活性明显低于对照。H~ -ATP酶的活性及其对寡霉素的敏感性都明显下降。ATP能量化后线粒体膜电位的变化也比对照明显降低。膜脂流动性低于对照。亚急克病人心肌线粒体内观察到较多的电子致密无定形物质,经电镜X射线微区等方法分析,认为这些物质不是Ca_3(PO_4)_2,而可能是一种蛋白质凝聚物。此外,心肌线粒体的硒含量远低于对照,而Ca含量明显高于对照。上述结果都反映亚急克病人心肌线粒体明显损伤。根据克山病患者心肌细胞线粒体结构与功能方面呈现的如此广泛与明显的异常,可将克山病称为“心肌线粒体病(Mitochondrial Cardiomyopathy)”。     

格列齐特对糖尿病大鼠心肌的保护作用及其机制*

目的: 观察格列齐特对糖尿病大鼠心肌保护作用及其可能的机制。方法: 将60只健康SD大鼠随机分为正常组(NC,n=10),造模组(n=50)给予高糖高脂饲料4周后,腹腔注射STZ(45 mg/kg)建立糖尿病大鼠模型,随机抽取以FBG≥16.7 mmol/L作为糖尿病模型建立成功。将造模成功的38只糖尿病大鼠随机分为模型组(MC,n=9)、格列齐特组(Glic,80 mg/kg,n=10)、格列本脲组(Glib,2.5 mg/kg,n=10)、法舒地尔组(Fas,10 mg/kg,n=9);NC组和MC组灌胃等容积蒸馏水,Glic组和Glib组灌胃给药,Fas组采用腹腔注射。各组大鼠每天给药一次,每周记录体质量及空腹血糖(FBG),持续8周。实验结束时取血并测定心脏质量,计算心脏质量指数(HWI);测定各组糖化血红蛋白(HbA1c)、总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白(HDL-C)、低密度脂蛋白(LDL-C)含量以及血清丙二醛(MDA)水平和超氧化物歧化酶(SOD)活性;通过HE和Masson染色,观察心肌病理变化和组织胶原纤维水平;TUNEL染色观察并计算心肌细胞凋亡率;Western blot法检测心肌组织中RhoA、ROCK1、eNOS、Bcl-2和Bax蛋白表达。结果: 与NC组比较,MC组FBG、HWI、HbA1c、TC、TG、LDL-C、MDA水平,心肌组织胶原沉积和心肌细胞凋亡率以及心肌组织中RhoA、ROCK1、Bax蛋白明显升高,SOD活性及HDL-C、eNOS、Bcl-2和体重显著降低(P＜0.01);与MC组相比,Glic组FBG、HWI、HbA1c、TC、TG、LDL-C和MDA等指标明显下降,心肌组织胶原沉积及心肌细胞凋亡减轻,心肌组织RhoA、ROCK1、Bax蛋白表达下调(P＜0.01或P＜0.05),大鼠体重和血清中SOD活性,HDL-C升高,eNOS、Bcl-2蛋白水平升高(P＜0.01或P＜0.05)。与Glic组相比,Glib组与Fas组体重、血脂、FBG、HWI、MDA以及心肌纤维化和心肌细胞凋亡水平升高,SOD和Bcl-2降低,Glib组心肌组织RhoA、ROCK1、Bax蛋白表达上调(P＜0.01或P＜0.05)。结论: 格列齐特可改善糖尿病大鼠心肌损伤并减轻心肌细胞凋亡水平,其机制可能与降低血糖,改善氧化应激状态,调控RhoA/ROCK1/eNOS信号通路有关。     

不同剂量链脲佐菌素腹腔注射制备大鼠糖尿病心肌病模型的病理学观察

建立糖尿病性心肌病（DCM）大鼠模型,观察不同剂量链脲佐菌素（STZ）单次腹腔注射后大鼠心肌和胰腺的病理学变化。用STZ 50 mg/kg、55 mg/kg、60 mg/kg 3种剂量单次腹腔注射,制备糖尿病大鼠模型;以柠檬酸三钠-柠檬酸缓冲液腹腔注射,作为对照。72 h后,测空腹血糖及做口服葡萄糖耐量实验（OGTT）;3周后,HE染色观察各组大鼠胰腺和心肌形态学变化,Masson三色染色观察心肌纤维化改变。OGTT和空腹血糖显示3组存活大鼠糖尿病均成模;3周末,50 mg/kg和55 mg/kg剂量死亡率为25%;60 mg/kg剂量高,达到75%;HE染色显示55 mg/kg剂量组大鼠胰岛明显萎缩,轮廓不清晰,胰岛细胞数量少,心肌细胞肥大、排列紊乱,细胞间隙增大,并有炎症细胞浸润;50 mg/kg组胰岛和心肌也有变化,但无55 mg/kg组明显。心肌Masson染色显示55 mg/kg组心肌内胶原组织明显增多,排列紊乱,分布不均。55 mg/kg剂量的STZ单次注射大鼠腹腔,造模3周可以建立较明显的DCM模型,可为DCM的组织病理学和实验研究提供一个较好的动物模型。     

Mice with defects in HB-EGF ectodomain shedding show severe developmental abnormalities

Heparin-binding EGF-like growth factor (HB-EGF) is first synthesized as a membrane-anchored form (proHB-EGF), and its soluble form (sHB-EGF) is released by ectodomain shedding from proHB-EGF. To examine the significance of proHB-EGF processing in vivo, we generated mutant mice by targeted gene replacement, expressing either an uncleavable form (HBuc) or a transmembrane domain-truncated form (HBdeltatm) of the molecule. HB(uc/uc) mice developed severe heart failure and enlarged heart valves, phenotypes similar to those in proHB-EGF null mice. On the other hand, mice carrying HBdeltatm exhibited severe hyperplasia in both skin and heart. These results indicate that ectodomain shedding of proHB-EGF is essential for HB-EGF function in vivo, and that this process requires strict control.     

Concentations of copper, Zinc, and magnesium in sera from patients with idiopathic dilated cardiomyopathy

Trace elements are known to have a key role in myocardial metabolism. The accumulation (cobalt, arsenic, copper) or deficiency (selenium, zinc) of trace elements may be responsible for idiopathic dilated cardiomyopathy. We investigated the trace element concentrations (Cu, Zn, Mg) in sera from patients with dilated cardiomyopathy by atomic absorption spectrophotometry. We observed that patients with dilated cardiomyopathies have higher copper and lower zinc concentrations in serum than healthy controls. The magnesium concentrations of patients did not differ significantly from that of control subjects.     

芹菜素改善酒精性骨质疏松症大鼠肠道菌群、调节骨钙代谢——

探究芹菜素改善酒精性骨质疏松症大鼠肠道菌群、调节骨钙代谢的作用。

60只SD健康大鼠采用随机数字表法分为模型组、正常组、常规治疗组以及芹菜素低、中、高剂量组,每组10只。模型组大鼠每天上午用白酒（10 mL/kg）灌胃+生理盐水（10 mL/kg）灌胃;正常组大鼠每天上午用生理盐水（10 mL/kg）灌胃+生理盐水（10 mL/kg）灌胃;常规治疗组大鼠每天上午用白酒（10 mL/kg）灌胃+碳酸钙、阿法D3混悬液（分别以85 mg/kg、0.05 μg/kg剂量溶于10 mL/kg生理盐水）灌胃;芹菜素低、中、高剂量组每天上午分别用白酒（10 mL/kg）灌胃+芹菜素溶液（分别以20、40、80 mg/kg剂量溶于10 mL/kg生理盐水）灌胃,每天1次,持续16周。使用双能X线骨密度检测仪测定各组大鼠右侧股骨骨密度;苏木素–伊红（HE）染色观察各组股骨组织病理学改变;16S核糖体脱氧核糖核酸（16S rDNA）测序技术检测各组肠道菌群多样性及门、属水平相对丰度;Connectify法测定各组骨钙（Ca）含量,改良Neuman-Lorgan法测定各组骨羟脯氨酸（HOP）含量,并计算二者比值。

模型组大鼠骨松质结构改变,骨小梁稀疏松散、粗细不匀,大量断裂,骨髓腔扩大明显,有大量纤维组织。常规治疗组和芹菜素3个剂量组以上病变情况均有不同程度改善,且芹菜素作用呈剂量依赖性,芹菜素中剂量组与常规治疗组差异不显著。与正常组比,模型组、常规治疗组和芹菜素3个剂量组大鼠骨密度、骨Ca、骨HOP含量及二者比值、Chao1指数、Ace指数以及肠道菌群厚壁菌门、毛螺旋菌属、粪球菌属、乳杆菌属、普氏菌属、罗氏菌属和布劳特菌属水平相对丰度降低,拟杆菌门、变形菌门、拟杆菌属、肠杆菌属和别样棒菌属水平相对丰度升高,差异均有统计学意义（均P＜0.05）;与模型组比,常规治疗组和芹菜素3个剂量组大鼠骨密度、骨Ca、骨HOP含量及二者比值、Chao1指数、Ace指数以及肠道菌群厚壁菌门、毛螺旋菌属、粪球菌属、乳杆菌属、普氏菌属、罗氏菌属和布劳特菌属水平相对丰度均升高,拟杆菌门、变形菌门、拟杆菌属、肠杆菌属和别样棒菌属水平相对丰度降低,差异均有统计学意义（均P＜0.05）,芹菜素对骨密度、骨Ca、骨HOP含量及二者比值、Chao1指数、Ace指数以及肠道菌群门、属水平相对丰度作用呈剂量依赖性,且芹菜素中剂量组与常规治疗组骨密度、骨Ca、骨HOP含量及二者比值、Chao1指数、Ace指数以及肠道菌群门、属水平相对丰度比较差异均无统计学意义（均P＞0.05）。

芹菜素能够提高酒精性骨质疏松症大鼠骨密度和骨Ca、骨HOP含量,推测是通过调节肠道菌群相对丰度,促进有益菌群生长,抑制致病菌群生长实现的。