新生儿窒息后血清心肌肌钙蛋白I的检测及其意义

目的　探讨血清心肌肌钙蛋白I(cTnI)评估新生儿窒息后的心肌损害的临床价值。方法　采用ELISA法对 2 0例窒息新生儿和 2 5例正常新生儿进行cTnI检测 ,同时检测肌酸磷酸激酶同功酶 (CK -MB)。结果　窒息组急性期血清cTnI、CK -MB水平明显高于对照组 (P <0 .0 5 ) ,且窒息时间越长 ,血清cTnI、CK -MB水平升高越明显 ,cTnI诊断新生儿窒息后心肌损伤的特异性均优于CK -MB。结论　血清cTnI和CK -MB的测定有助于早期预测心肌细胞损害 ,cTnI优于CK -MB     

兔抗人心肌肌钙蛋白I抗体的制备与鉴定

目的制备兔抗人心肌肌钙蛋白I抗体并进行鉴定。方法用人工合成的cTnI蛋白免疫新西兰兔制备多克隆抗体,ELISA及Western blot方法检测制备的抗血清效价和特异性。结果此次获得的抗血清 ELISA方法检测抗体滴度达到了1:16 000,检测cTnI的灵敏度最低为10μg/L。Western blot检测表明该抗体可有效识别原核细胞表达及大鼠心脏组织提取物中存在的cTnI蛋白。结论应用该方法成功制备了人cTnI的多克隆抗体,为进一步研究cTnI的结构与功能打下基础,并为有效制备高特异性的单克隆抗体提供借鉴。     

Experimental doxycycline overdose in rats causes cardiomyopathy

All reports of doxycycline‐induced cardiomyopathy to date have been limited to accidental oral poisoning in calves. Therefore, the current study investigated the cardiomyotoxic effect of experimental doxycycline overdose in rats as a toxicity model which could be monitored using histopathological and biochemical assays. A total of 38‐week‐old male Wistar rats were divided into three groups consisting of 10 each. The first group was an untreated control group (D₀), and the second group (D₅) received doxycycline hyclate 25 mg/kg intragastrically twice daily (8 AM and 8 PM), which is 5‐fold higher than the standard dose. The third group (D₁₀) received 50 mg/kg intragastrically twice daily (8 AM and 8 PM), which is 10‐fold higher than the standard dose. The dose continued for 10 consecutive days and revealed that the doxycycline toxicity was dose dependent. Mortality was recorded in the D₁₀ group only (30%). The D₅ rats exhibited minimal skeletal muscle injury and slight but significant increases in the skeletal muscle damage indicators creatine kinase (CK) and aspartate aminotransferase (AST) compared to controls. The cardiac muscle of the D₅ rats was histologically normal, and the D₅ rats also exhibited normal levels of troponin I (cTnI), an indicator of cardiac muscle damage. In contrast, the D₁₀ rats displayed cardiomyopathy, as well as significant increases in the muscle enzymes alanine aminotransferase (ALT), AST and CK and the cardiac damage indicator cTnI compared to control and D₅ groups. Pulmonary lesions were observed in the D₁₀ rats, primarily cardiac lesion‐related alveolar heart failure cells. Thus the present study is the first to demonstrate that oral doxycycline poisoning (10 times the therapeutic dose)‐induced cardiomyopathy is not limited to calves and could occur without any predisposing factors.     

cTnI在急性冠脉综合征早期诊断中的临床研究

目的评价心肌标志物肌钙蛋白I(cTnI)快速定量检测系统在急性冠脉综合征早期诊断的准确性和省时性,为尽早进行介入治疗赢得时间。方法本研究采用随机、自身对照的试验设计。对符合入选标准的150例患者采取血样,分别进行cTnI快速定量检测和实验室常规心肌酶检测,观察与比较两种检测结果及得出结果时间。结果 cTnI快速定量检测与实验室心肌酶检测结果的准确性一致,但cTnI快速定量检测明显快于实验室常规检测。结论 cTnI快速定量检测系统有利于急性冠脉综合征的早期诊断。     

心肌肌钙蛋白I、肌钙蛋白T和NT-proBNP联合检测急性心肌梗死的诊断价值探讨

目的：探讨血中肌钙蛋白I(cTnI)、肌钙蛋白T(cTnT)、N端前B型脑钠肽(NT-proBNP)联合检测在急性心肌梗死(acute myocardial infarction,AMI)诊断中的应用价值。方法选取急性胸闷胸痛为主要症状的患者34例,以2010年AMI临床诊断与治疗指南将受试者分为AMI组（n=20）和非AMI组（n=14）。就诊时即抽取血样,用电化学发光法法测定入组者血浆中的cTnI、cTnT、NT-proBNP的浓度。结果 AMI患者NT-proBNP浓度均值为3580.40 pg/mL,非AMI组为167.6 pg/mL,NT-proBNP浓度较对照组明显升高,差异有统计学意义(P＜0.05);cTnI、cTnT浓度较非AMI组亦明显升高,差异有统计学意义(P＜0.05)。结论 NT-proBNP、cTnI、cTnT联合检测可以使AMI检测的敏感性升高,有助于AMI的早期诊断。     

阿托伐他汀联合米力农治疗慢性心力衰竭的临床研究

目的探讨阿托伐他汀钙联合米力农注射液治疗慢性心力衰竭的临床疗效。方法选取2018年12月—2019年12月于河南省人民医院进行治疗的慢性心力衰竭患者93例,随机分为对照组(46例)和治疗组(47例)。对照组iv米力农注射液,首次采用50μg/kg负荷剂量静脉推注10 min,随后以0.25～0.50μg/(kg·min)静脉匀速泵入,连续使用72 h;治疗组患者则在对照组基础上口服阿托伐他汀钙片,10 mg/次,2次/d。两组均连续治疗1周。观察两组的临床疗效,比较两组治疗前后临床症状评分、6 min步行距离、心功能指标及血清去甲肾上腺素、细胞间黏附分子-1(ICAM-1)、超敏C反应蛋白(hs-CRP)、醛固酮(ALD)、脑自然肽氨基端前体蛋白(NT-proBNP)、心肌肌钙蛋白I(cTnI)水平。结果治疗后,对照组临床总有效率78.26%明显低于治疗组93.62%,两组比较差异具有统计学意义(P0.05)。治疗后,两组患者临床症状评分显著降低,但6 min步行距离显著升高(P0.05);且治疗后治疗组临床症状评分和6 min步行距离相较于对照组改善更为显著(P0.05)。治疗后,两组患者心功能指标左心室射血分数(LVEE)、左心室收缩末内径(LVESD)、左心室收缩末期容积(LVESV)均较治疗前明显改善(P0.05);且治疗后治疗组心功能相关指标相较于对照组改善更为显著(P0.05)。治疗后,两组患者血清去甲肾上腺素、ICAM-1、hs-CRP、ALD、NT-proBNP、cTnI水平均较治疗前明显降低(P0.05);且治疗后治疗组这些相关血清生化指标显著低于对照组(P0.05)。结论阿托伐他汀钙联合米力农注射液治疗慢性心力衰竭疗效确切,能显著改善患者临床症状及心功能指标,可改善患者相关血清生化指标,具有一定的临床推广应用价值。     

Phosphorylation of human cardiac troponin I G203S and K206Q linked to familial hypertrophic cardiomyopathy affects actomyosin interaction in different ways

cAMP-dependent protein kinase (PKA)-dependent phosphorylation of the two serine residues in the amino terminal region unique to cardiac troponin I (cTnI) is known to cause two effects: (i) decrease of the maximum Ca2+-controlled thin filament-activated myosin S1-ATPase (actoS1-ATPase) activity and mean sliding velocity of reconstituted thin filaments; (ii) rightward shift of the Ca2+ activation curves of actoS1-ATPase activity, filament sliding velocity, and force generation. We have studied the influence of phosphorylation of human wild-type cTnI and of two mutant cTnI (G203S and K206Q) causing familial hypertrophic cardiomyopathy (fHCM) on the secondary structure by circular dichroism spectroscopy and on the Ca2+ regulation of actin-myosin interaction using actoS1-ATPase activity and in vitro motility assays. Both mutations slightly influence the backbone structure of cTnI but only the secondary structure of cTnI-G203S is also affected by bis-phosphorylation of cTnI. In functional studies, cTnI-G203S behaves similarly to wild-type cTnI, i.e. the mutation itself has no measurable effect and bis-phosphorylation alters the actoS1-ATPase activity and the in vitro thin filament motility in the same way as does bis-phosphorylation of wild-type cTnI. In contrast, the mutation K206Q leads to a considerable increase in the maximum actoS1-ATPase activity as well as filament motility compared to wild-type cTnI. Bis-phosphorylation of this mutant cTnI still suppresses the maximum actoS1-ATPase activity and filament sliding velocity but does no longer affect the Ca2+ sensitivity of these processes. Thus, these two fHCM-linked cTnI mutations, although reflecting similar pathological situations, exert different effects on the actomyosin system per se and in response to bis-phosphorylation of cTnI.     

移动差值控制图评估临床实验室肌钙蛋白不确定度

目的运用控制图评估肌钙蛋白I(cTnI)测量不确定度。方法采用日本东曹AIA-1800全自动荧光磁微粒酶免分析仪测定cTnI控制品,1次/天,共30d;用Anderson-Darling法检验数据的正态分布性和独立性;建立单值-移动差值及指数加权移动平均值控制图及评估不确定度。结果 Anderson-Darling检验cTnI质控数据为正态分布性且具有独立性,结果测量不确定为(0.218±0.016)μg/L,(k=2)。结论移动极差控制图法可用来评估cTnI结果不确定度,本研究为临床实验室评价不确定度提供了新的思路。     

血清肌钙蛋白I质控物的研究

目的评价自制血清肌钙蛋白I(cTnI)质控物均匀性和稳定性。方法按实验设计收集混合血清,分装-20℃贮存。参照CNAS-GL03《能力验证样品均匀性和稳定性评价指南》,对质控物的均匀性进行评价;运用恒温加速试验研究稳定性。结果质控物均匀性差异无统计学意义(P0.05)。恒温加速试验显示,血清cTnI降解随时间变化符合化学动力学一级反应,根据Arrhenius方程推测4℃贮存7d,-20℃贮存有效期为19个月;监测质控物9个月,与恒温加速试验结果一致。结论自制血清cTnI质控物均匀性、稳定性良好,可用于临床室内质量控制。     

Cardiac troponin in ischemic cardiomyocytes: Intracellular decrease before onset of cell death

Aim

Cardiac troponin I (cTnI) and T (cTnT) are the most important biomarkers in the diagnosis of acute myocardial infarction (AMI). Nevertheless, they can be elevated in the absence of AMI. It is unclear if such elevations represent irreversible cardiomyocyte-damage or leakage from viable cardiomyocytes. Our objective is to evaluate whether cTn is released from viable cardiomyocytes in response to ischemia and to identify differences in the release of cTn and its molecular forms.

Methods and results

HL-1 cardiomyocytes (mouse) were subjected to ischemia (modeled by anoxia with glucose deprivation). The total contents and molecular forms of cTn were determined in culture media and cell lysates. Cell viability was assessed from the release of lactate dehydrogenase (LDH). Before the release of LDH, the intracellular cTn content in ischemic cells decreased significantly compared to control (52% for cTnI; 23% for cTnT) and was not matched by a cTn increase in the medium. cTnI decreased more rapidly than cTnT, resulting in an intracellular cTnT/cTnI ratio of 25.5 after 24 h of ischemia. Western blots revealed changes in the relative amounts of fragmented cTnI and cTnT in ischemic cells.

Conclusions

HL-1 cardiomyocytes subjected to simulated ischemia released cTnI and cTnT only in combination with the release of LDH. We find no evidence of cTn release from viable cardiomyocytes, but did observe a significant decrease in cTn content, before the onset of cell death. Intracellular decrease of cTn in viable cardiomyocytes can have important consequences for the interpretation of cTn values in clinical practice.