BUN/Cr、cTnⅠ、NT-proBNP在不同严重程度的急性左心衰竭患者中的诊断价值

目的:评估血尿素氮/肌酐比(blood urea nitrogen/creatinine ratio,BUN/Cr)、心肌肌钙蛋白Ⅰ(cardiac troponinⅠ,cTnⅠ)和N末端B型利钠肽原(NT-proBNP)在诊断急性左心衰竭患者的严重程度方面的有效性。方法:选取连云港市第二人民医院检验科2023年1月—2024年2月接收的122份急性左心衰竭患者的血清样本作为研究样本,根据急性生理学及慢性健康状况评分Ⅱ(APACHEⅡ)将患者分为轻症组(APACHEⅡ评分≤20分,45例)、重症组(APACHEⅡ评分21~30分,42例)及极重症组(APACHEⅡ评分≥31分,35例)。比较三组患者的血清BUN/Cr、cTnⅠ及NT-proBNP水平,采用Spearman分析评估血清BUN/Cr、cTnⅠ及NT-proBNP水平与急性左心衰竭患者严重程度的相关性,并构建受试者操作特征(ROC)曲线分析血清BUN/Cr、cTnⅠ及NT-proBNP水平对极重症急性左心衰竭患者的诊断价值。结果:极重症组的血清BUN/Cr、cTnⅠ及NT-proBNP水平均高于重症组、轻症组,且重症组均高于轻症组,差异均有统计学意义(P<0.05);相关性分析结果显示,血清BUN/Cr、cTnⅠ及NT-proBNP水平与急性左心衰竭患者的严重程度呈正相关(P<0.05);ROC曲线分析结果显示,血清BUN/Cr、cTnⅠ及NT-proBNP联合检测的敏感度、特异度分别为94.3%、90.8%,ROC曲线下面积(AUC)为0.969,优于单独检测。结论:在急性左心衰竭患者中,血清BUN/Cr、cTnⅠ及NT-proBNP的水平与疾病严重程度相关,联合检测可以有效诊断急性左心衰竭患者的疾病严重程度,具有较高的敏感度和特异度。

电刺激和延迟冷却对宰后牛肉肌原纤维Troponin-T降解的影响

为了探讨牛肉嫩化的机理,选择24头24月龄,体重约500kg杂交牛(鲁西黄牛×西门塔尔)随机分成4组,在宰前或宰后分别进行以下4种处理:常规预冷组,延迟冷却组,电刺激处理组,电刺激和延迟冷却处理组。用SDS-PAGE和蛋白免疫印迹的方法比较分析了4种处理牛肉成熟1,3,7,10d其肌原纤维骨架蛋白Troponin-T的降解情况。结果表明:与常规冷却组相比,电刺激处理在1、3、7d时显著加快了Troponin-T的降解,而10d时差异不显著;延迟冷却处理在1、3d时显著加快了Troponin-T的降解,而7、10d时差异不显著;1、3d时延迟冷却对Troponin-T的降解影响比电刺激显著,而7、10d时则是电刺激比较显著;电刺激和延迟冷却处理的结合对Troponin-T降解的影响比电刺激处理组、延迟冷却处理组显著。综上可见,延迟冷却、电刺激无论在速度和数量上显著加快了Troponin-T的降解,加快了牛肉成熟,缩短了成熟时间,且二者有协同作用。

血清Troponin I,CK-MBmass,Myoglobin在急性心肌梗塞诊断中的应用评价

为了解CTnI，CK－MBmass和Mb指标对急性心肌梗塞（AMI）早期诊断、后期监测及预后判断的临床意义，采用微粒子化学发光法，对20例AMI患者、24例不稳定心绞痛（UA）患者、17例骨骼肌损伤（SM）患者和19例健康者（对照组）进行血清CTnI，CK－MBmass和Mb的测定，并对AMI患者胸病发生3～5小时，8～14小时，20～24小时，72小时和7天共五个时段进行了测定。结果：AMI患者发病早期CTnI，CK－MBmass和Mb的阳性检出率分别为65％，70％，70％，CTnI在UA患者组和SM患者组中未检出。CTnI，CK－MBmass和Mb测定值含量在AMI组中明显高于UA组和SM组，AMI患者组CTnI分别是UA组和SM组的84倍和91.63倍，CK－Mbmass分别是该二组的8．82倍和4．67倍，Mb分别是该二组的11．57倍和2．25倍，AMI组与UA组和SM组比较，有显著性差异（P＜0．001）。AMI患者组中该三项指标的动态测定显示，在疾病发生早期（3～5小时）时，CTnI，CK－MBmass和Mb都有显著性升高，随时间延长而逐渐升高，高峰值期均在8～14小时段，72小时时Mb已基本回到正常。7天时血清中仍有CTnI的持续存在，但CK－MBmass已接近正常。以上显示，CTnI，CK－MBmass和Mb在早期诊断AMI时，都具有较高的敏感性，CTnI在AMI患者中的阳性检出率具有心肌特异性。

糖尿病肾脏疾病透析患者肌钙蛋白T水平的变异及临床价值分析

目的明确肌钙蛋白T(troponin T,TnT)在糖尿病肾脏疾病(diabetic kidney disease,DKD)透析患者中的变异情况,评价TnT对DKD透析患者的临床价值。方法对2014年1月1日至2020年8月31日山东省济南市中心医院8553例透析患者及其TnT值进行筛选,依据患者的纳入与排除标准筛除5692例,排除不符合TnT入选标准者2485例,最后入选376例患者。入选患者根据原发疾病分为DKD透析组和非糖尿病肾脏疾病(non-diabetic kidney disease,NDKD)透析组,比较2组患者TnT基线水平的差异,并采用受试者工作特征曲线确立诊断急性心肌梗死的最佳阈值,进一步分析DKD透析患者TnT基线的影响因素及与预后不良的关系。结果DKD透析组患者TnT基线水平(267.27 ng/L)明显高于NDKD透析组患者(76.09 ng/L),是NDKD透析组的3.51倍;NDKD透析组患者诊断急性心肌梗死的最佳阈值为166.85 ng/L,DKD透析组患者的最佳阈值为367.45 ng/L;DKD透析组中男性的TnT基线水平高于女性,TnT基线水平与年龄、糖尿病视网膜病变程度、下肢血管病变程度呈正相关,与血红蛋白、白蛋白呈负相关。随着TnT基线水平逐级递增,DKD透析组患者心肌梗死率、心因性病死率、糖尿病足部溃疡率、全因死亡率也逐级升高。结论DKD透析组患者的TnT基线水平明显高于NDKD透析组患者,且诊断急性心肌梗死时需要更高的阈值。TnT基线水平升高受糖尿病血管并发症等因素影响,可作为不良事件的预后指标。

牙周炎与肌钙蛋白关系的研究进展

肌钙蛋白是存在于心肌表面的一种特殊蛋白,是心肌细胞特有的组成成分,慢性牙周炎是以菌斑微生物为始动因子的慢性感染性疾病。在牙周炎发展过程中,牙周袋中的牙周致病菌及其相关因子增多,从而诱导Ca2+通道打开,Ca2+进入内皮细胞和心肌细胞,造成心肌细胞损伤,肌钙蛋白复合物水解,使血清肌钙蛋白水平升高,肌钙蛋白可诱导牙周黏附分子等表达,使炎性细胞黏附,最终导致牙周炎进一步发展。综述两者的关系及相关机制。

人Troponin I的表达载体构建诱导表达和纯化及活性测定

以人肝脏cDNA文库为模板,通过PCR方法扩增出Tropon in基因,将其克隆到pCR-TOPO质粒中,构建表达质粒pET-22 b(+)-TnI,转化大肠杆菌BL 21(DE 3)-RPX并进行诱导表达,表达的目的蛋白占菌体总蛋白的20%以上并主要以可溶形式存在。建立了Tropon in I的非亲和色谱纯化工艺,纯化后蛋白产量约为20 mg/L,纯度在90%以上。体外活性实验表明重组蛋白具有良好的抗血管生成。

troponin Ⅰ的原核表达及其抗血管生成活性的初步研究

为了建立肌钙蛋白-Ⅰ(troponinⅠ,TnⅠ)的原核表达,试验以人肝脏cDNA文库为模板,通过PCR方法扩增出肌钙蛋白-Ⅰ基因,将其克隆到PCR-TOPO质粒中,构建表达质粒pET-22b(+)-TnⅠ,转化大肠杆菌BL21(DE3)-RPX并进行诱导表达。结果表明:表达的目的蛋白占菌体总蛋白的20%以上,并主要以可溶形式存在。说明试验建立了troponinⅠ的非亲和色谱纯化工艺,重组蛋白具有良好的抗血管生成活性。

cTnI、CTGF、AngⅡ和miR-21在老年性慢性心力衰竭肺部感染中的诊断价值

目的探讨心肌肌钙蛋白I(cTnI)、结缔组织生长因子(CTGF)、血管紧张素Ⅱ(AngⅡ)和微小核糖核酸-21(miR-21)在老年性慢性心力衰竭肺部感染中的诊断价值。方法选取郑州市金水区总医院2022年1月至2023年8月收治的70例老年性慢性心衰肺部感染患者作为合并感染组,同期70例老年单纯心衰患者作为单纯心衰组,以及同期70例老年健康体检者作为对照组。比较三组研究对象临床指标及cTnI、CTGF、AngⅡ、miR-21水平,比较合并感染组不同心功能分级cTnI、CTGF、AngⅡ、miR-21水平,分析老年性慢性心衰肺部感染与cTnI、CTGF、AngⅡ、miR-21相关性。结果合并感染组血清cTnI、CTGF、AngⅡ、miR-21均高于单纯心衰组和对照组,单纯心衰组高于对照组,差异有统计学意义(P<0.05);合并感染组心功能Ⅳ级患者血清cTnI、CTGF、AngⅡ、miR-21高于Ⅲ级和Ⅱ级,Ⅲ级高于Ⅱ级,差异有统计学意义(P<0.05);血清cTnI、CTGF、AngⅡ、miR-21均为老年性慢性心衰肺部感染的独立危险因素(P<0.05);Pearson相关性分析显示,老年性慢性心衰肺部感染与血清cTnI、CTGF、AngⅡ、miR-21水平呈正相关关系(r=0.566、0.543、0.555、0.582,P<0.05)。结论老年性慢性心力衰竭肺部感染患者多伴有血清cTnI、CTGF、AngⅡ、miR-21升高,cTnI、CTGF、AngⅡ、miR-21与老年性慢性心衰肺部感染存在相关性。

Diagnostic and prognostic value of minor elevated cardiac troponin levels for percutaneous coronary intervention-related myocardial injury:a prospective,single-center and double-blind study

Cardiac troponin-I （cTnI） and -T （cTnT） are sensitive and specific markers of myocardial injury. However, the role of increased cTnI and cTnT in percutaneous coronary intervention （PCI）-related myocardial injury remains controversial. In this prospective, single-center and double-blind study, we aimed to determine the diagnostic and prognostic value of cTnI as well as cTnT （cTns） in PCI-related myocardial injury in a Chinese population. A total of 1,008 patients with stable angina pectoris and non-ST-segment elevation acute coronary syndrome were recruited. The levels of cTnI and cTnT were examined before and after PCI. All patients were followed up for 26± 9 months to observe the incidence of major adverse cardiac events （MACEs）. Our results showed that post- PCI cTnI and/or cTnT levels were increased to more than the 99^th percentile upper reference limit （URL） in 133 （13.2%） patients, among which 22 （2.2%） were more than 5 × 99^th percentile URL. By univariate analysis, an elevation in cTns after PCI was not an independent predictor of increased MACEs, HR 1.35 （P = 0.33, 95% CI： 0.74-2.46）. In conclusion, our data demonstrate that the incidence of PCI-related myocardial injury is not common in a Chinese population and minor elevated cTns levels may not be a sensitive prognostic marker for MACEs.

Preparation of Anti-cardiac Troponin I Monoclonal Antibodies and Their Characterization with Surface Plasmon Resonance Biosensor

Cardiac troponin I(cTnI) was separated and purified from human left ventricular tissue by affinity chromatographic method and used to immunize Balb/c mice by intraperitoneal injection and four hybridoma cell lines, which secreted monoclonal antibody(mAb) against human cTnI, were obtained by cell fusion, identification and cloning twice. Three mAbs(9F5, 2F11, 8C12) were produced from the ascites of Balb/c mice injected intraperitoneally the hybridoma cells and characterized by means of a surface plasmon resonance(SPR) biosensor. An optimal and specific sensing membrane for troponin I was prepared with staphylococcal protein A(SPA) as the intermediate layer and mAb against human cTnI as the capture antibody. On the basis of the sensing membrane, two modes of operation of the SPR biosensor were developed, i.e ., a direct detection of antigen antibody affinity and a sandwich assay. In the sandwich assay detection mode, the mAbs competition was measured by monitoring whether the secondary antibody had been attached to the cTnI already captured by the first antibody on the sensor surface. The SPR biosensor was shown to be able to directly detect the antigen antibody affinity and the order of the affinity was found to be 9F5>2F11>8C12. In the sandwich detection mode, it was found that the different epitopes on the cTnI molecules were recognized by the three mAbs respectively, but the asymmetrical competition was shown between 2F11 and 8C12 and no competition was found between 9F5 and 2F11 or 8c12. Based on these results, a double monoclonal sandwich immunoassay for cTnI was developed by using the optimal antibody pair of 9F5 and 2F11 and the SPR biosensor with SPA substrate membrane, which showed an excellent sensitivity of 0.8 μg/L for both the buffer and the serum samples compared with the direct detection of cTnI for the buffer with the lowest detection limit of 4 μg/L and conventional ELISA with the sensitivity of 1.9 μg/L.

High-sensitivity cardiac troponins in everyday clinical practice

High-sensitivity cardiac troponin(hs-cTn) assays are increasingly being used in many countries worldwide,however,a generally accepted definition of high-sen-sitivity is still pending.These assays enable cTn mea-surement with a high degree of analytical sensitivity with a low analytical imprecision at the low measuring range of cTn assays(coefficient of variation of < 10% at the 99th percentile upper reference limit).One of the most important advantages of these new assays is that they allow novel,more rapid approaches to rule in or rule out acute coronary syndromes(ACSs) than with previous cTn assay generations which are still more commonly used in practice worldwide.hs-cTn is also more sensitive for the detection of myocardial damage unrelated to acute myocardial ischemia.Therefore,the increase in early diagnostic sensitivity of hs-cTn assays for ACS comes at the cost of a reduced ACS specificity,because more patients with other causes of acute or chronic myocardial injury without overt myocardial isch-emia are detected than with previous cTn assays.As hs-cTn assays are increasingly being adopted in clinical practice and more hs-cTn assays are being developed,this review attempts to synthesize the available clinical data to make recommendations for their everyday clini-cal routine use.

Comparison of plasma microRNA-1 and cardiac troponin T in early diagnosis of patients with acute myocardial infarction

BACKGROUND:Early reperfusion can effectively treat acute myocardial infarction(AMI) and reduce the mortality signif icantly. This study aimed to compare the role of plasma microRNA-1(miR-1) and cardiac troponin T(cTnT) in early diagnosis of AMI patients.METHODS:From May 2011 to May 2012,plasma samples were collected from 56 AMI patients and 28 non-AMI controls. The expression of plasma miR-1 was measured by quantitative reverse transcription-polymerase chain reaction(qRT-PCR),and the level of plasma cTnT was measured using electrochemiluminescence-based methods on an Elecsys 2010 Immunoassay Analyzer. SPSS 16.0 was used for the statistical analysis of the results. Data were expressed as mean±standard deviation unless otherwise described. The differences about clinical characteristics between the AMI patients and controls were tested using Student's t test or Fisher's exact test. The Mann-Whitney U test was conducted to compare the expression of microRNAs between the AMI patients and controls. MicroRNAs expression between different intervals of the AMI patients was compared using Wilcoxon's signed-rank test. The receiver operating characteristic(ROC) curve was established to discriminate the AMI patients from the controls.RESULTS:In the present study,the expression of plasma miR-1 was signifi cantly increased in the AMI patients compared with the healthy controls(P<0.01). The plasma miR-1 in the AMI patients decreased to the normal level at 14 days(P>0.05). The expression of plasma miR-1 was not related to the clinical characteristics of the study population(P>0.05). ROC curve analyses demonstrated that miR-1 was specifi c and sensitive for the early diagnosis of AMI,but not superior to cTnT.CONCLUSION:Plasma miR-1 could be used in the early diagnosis of AMI,but it is similar to cTnT.

Physician-level variation in the diagnosis of myocardial infarction and the use of angiography among veterans with elevated troponin

Background:Cardiac troponin assays have improved the ability to detect myocardial damage.However,ascertaining whether troponin elevation is due to myocardial infarction(MI) or secondary to another process can be challenging.Our aim is to evaluate provider-level variation in the diagnosis of MI and the use of invasive coronary angiography(ICA) among patients with undifferentiated elevations in cardiac troponin.Methods:We analyzed data from all patients with elevated troponin levels in a single Veterans Affairs(VA) Medical Center between 2006 and 2007.One of several cardiologists prospectively evaluated each patient's presentation and course of care.We compared the frequency of MI diagnosis and ICA use between physicians using univariate odds ratios(OR).Results:Among 761 patients,34.0% were diagnosed with MI and 25.9% underwent ICA.The unadjusted rates of MI(23.9% to 56.7%,P=0.02) and ICA(17.3% to 73.3%,P<0.001) differed between physicians.Comparing the patient cohorts for each physician,baseline characteristics were similar except for chest pain.In multivariate regression,factors associated with the use of cardiac ICA included an abnormal electrocardiograph(ECG)(OR=1.89,P=0.014),level of troponin(OR=1.71,P=0.004),chest pain(OR=8.60,P<0.001),and care by non-VA physicians(OR=4.45,P=0.006).One physician had a lower ICA use(OR=0.56,P=0.017).In multivariate regression of MI,no physician-level variation was observed.Conclusion:Among patients with elevated troponin,the likelihood of being diagnosed with MI and undergoing ICA is dependent on their clinical presentation.After adjustment,physician-level variation in care was observed for the use of ICA,but not for the diagnosis of MI.

Typical rise and fall of troponin in(peri-procedural) myocardial infarction:A systematic review

AIM: To identify the typical shape of the rise and fall curve of troponin(Tn) following the different types of myocardial infarction(MI). METHODS: We conducted a systematic search in PubM ed and Embase including all studies which focused on the kinetics of Tn in MI type 1, type 4 and type 5. Tn levels were standardized using the 99 th percentile, a pooled mean with 95%CI was calculated from the weighted means for each time point until 72 h. RESULTS: A total of 34 of the 2528 studies identified in the systematic search were included. The maximum peak level of the Tn was seen after 6 h after successful reperfusion of an acute MI, after 12 h for type 1 MI and after 72 h for type 5 MI. In type 1 MI there were additional smaller peaks at 1 h and at 24 h. After successful reperfusion of an acute MI there was a second peak at 24 h. There was not enough data available to analyze the Tn release after MI associated with percutaneous coronary intervention(type 4).CONCLUSION: The typical rise and fall of Tn is different for type 1 MI, successful reperfusion of an acute MI and type 5 MI, with different timing of the peak levels and different slopes of the fall phase.

Molecular Cloning and Tissue Distribution of Troponin I from the Japanese Pearl Oyster, <i>Pinctada fucata</i>

Troponin is a complex of three proteins (troponin I, troponin C, and troponin T) that binds Ca2+ and is a thin filament-associated regulator of vertebrate striated muscle contraction. The function of troponin I (TnI) in vertebrates has been extensively characterized, but its role in molluscan muscles has not yet been elucidated. Our previous work suggested that the troponin C subunit has a role in adductor phasic muscle but not in catch muscle. Here, we investigated the molecular characteristics of TnI from the bivalve Japanese pearl oyster, Pinctada fucata to aid the elucidation of the function of molluscan muscle troponin. We determined the primary structure of the full-length TnI protein from the P. fucata adductor muscle (Pifuc-TnI) and found that it is composed of 286 amino acid residues with a predicted molecular weight of 33,737. Motif structure predictions and multiple sequence alignments revealed that Pifuc-TnI has a 138 residue extension at its N-terminus compared with rabbit TnI. This is analogous to characterized TnIs from other mollusks. However, unlike scallop TnI, Pifuc-TnI is predicted to contain two cAMP-dependent protein kinase phosphorylation sites, at residues 39 - 45 (RRGTEDD) and 145 - 151 (KKKSKRK). Phylogenetic analysis indicated that Pifuc-TnI and molluscan TnIs were grouped into the same clade. Pifuc-TnI gene structure predictions using Splign alignment of our obtained cDNA and genome sequences indicated that Pifuc-TnI consists of fifteen exons, with the start and stop codons located in exon 2 and exon 11, respectively. Using quantitative real-time PCR, we determined that the Pifuc-TnI gene is predominantly expressed in adductor phasic muscle, weakly in adductor catch muscle, and is not expressed in the gill, mantle or foot. These findings suggest that TnI, as a component of the troponin complex, plays a regulatory role in adductor phasic muscle contraction, but not in catch contraction.

Molecular Cloning and Tissue Distribution of Troponin C from the Japanese Pearl Oyster, <i>Pinctada fucata</i>

Troponin C (TnC) is one of the subunits of troponin. Troponin, which is activated by Ca2+ binding, is a thin filament-associated regulator of vertebrate striated muscle contraction. The function of TnC in vertebrates has been characterized in detail, but the role of TnC in molluscan muscles is still unclear. In this work, we investigated whether TnC plays a role in the catch contraction of molluscan smooth muscle in the bivalve Japanese pearl oyster Pinctada fucata. We determined the full-length primary structure of the TnC protein from the P. fucata adductor muscle (Pifuc-TnC), and found it is composed of 150 amino acid residues with a predicted molecular weight of 17,400. Multiple sequence alignments indicated that it had four EF-hand motifs, but only one (site IV) was predicted to have Ca2+-binding ability. This is analogous to characterized TnCs from other mollusks. Three-dimensional modeling of Pifuc-TnC using SWISS-MODEL indicated the presence of a short loop within the α-helix connecting the site II and III EF-hand motifs. We predicted the gene structure of Pifuc-TnC using Splign alignment of our obtained cDNA and genome sequences and elucidated that Pifuc-TnC consists of five exons, with the start and stop codons located in exon 1 and exon 5, respectively. Using quantitative real-time PCR, we determined that the Pifuc-TnC gene is predominantly expressed in adductor phasic muscle and rarely in adductor catch muscle, gill, mantle and foot. These findings suggest that TnC may not have a role in catch muscle contraction.

Impact of training specificity on exercise-induced cardiac troponin elevation in professional athletes: A pilot study

BACKGROUND Release of cardiac biomarkers is common after strenuous endurance exercise,but data on intermittent exercise are scarce.It has not been investigated whether cardiac troponin elevation is influenced depending on the type of exercise that an athlete is adapted to perform.We hypothesized that intermittent but not continuous exercise induces cardiac troponin elevation in professional athletes adapted to high-intensity intermittent exercise.AIM To examine how training specificity impacts high-sensitivity cardiac troponin T(hs-cTnT)release.METHODS Nine professional floorball players participated in the study,which comprised two different exercise tests:a continuous incremental cycle ergometer test and a Yo-Yo Intermittent Recovery 2(Yo-Yo IR2)test.Serial assessment of hs-cTnT was performed after the cycle ergometer test and the Yo-Yo IR2 test(baseline,0,2,6,and 24 h).RESULTS No hs-cTnT elevation above the myocardial damage cutoff(≥14 ng/L)was shown after the cycle ergometer test,whereas hs-cTnT levels rose over the cutoff in three of nine participants after the Yo-Yo IR2 test.The hs-cTnT levels peaked at 6 h after both tests,but were significantly higher after the Yo-Yo IR2 test compared to the cycle ergometer test(median hs-cTnT concentration 10.6 ng/L vs 7.8 ng/L,P=0.038).All levels returned to baseline within 24 h.CONCLUSION In professional athletes adapted to high-intensity intermittent exercise,hs-cTnT was significantly elevated after intermittent but not continuous exercise.This principle of specificity training should be considered when designing future studies to avoid misinterpretation of hs-cTnT elevation.

Troponin T from the Japanese Pearl Oyster <i>Pinctada fucata</i>: Molecular Cloning, Tissue Distribution, Gene Structure, and Interaction Analysis with Tropomyosin

Troponin (Tn) is composed of three subunits (TnI, TnC and TnT) that bind Ca2+ and regulate striated muscle contraction in vertebrates. TnT’s function has been extensively described in vertebrates, but its role has been obscure in molluscan muscles. Our previous work indicated that the TnC and TnI subunits work in adductor phasic muscle, but not in catch muscle. Here, we have characterized TnT from the Japanese bivalve pearl oyster Pinctada fucata to start to explain the function of Tn in molluscan muscle contraction. We determined the primary structure of the full-length TnT protein from the P. fucata adductor muscle (Pifuc-TnT), and found that it is composed of 316 amino acid residues with a predicted molecular mass of 37.4 kDa. Multiple sequence alignment showed that Pifuc-TnT has an extension of >60 residues at the C-terminus that are not present in vertebrate TnTs, including known TnTs from other mollusks. Pifuc-TnT gene structure predictions using Splign alignment of the cDNA generated in this study and genome sequences indicated that Pifuc-TnT consists of 13 exons. Start and stop codons are located in exons 2 and 12, respectively. Quantitative real-time PCR revealed that the Pifuc-TnT gene was predominantly expressed in adductor phasic muscle, weakly in adductor catch muscle, slightly in gill, and not at all in mantle and foot. These findings suggest that TnT plays a regulatory role in adductor phasic muscle contraction, but not in catch contraction. Isothermal titration calorimetry revealed that unlike vertebrate TnTs, Pifuc-TnT does not interact with P. fucata tropomyosin-1 nor with tropomyosin-2. These findings in P. fucata imply that Tn functions differently in molluscan muscle than it does in vertebrates.

Troponin based studies in search of a biomarker for cardiac arrest

Cardiac arrest is shown to be a cause of a large number of deaths not only in Pakistan but around the globe. The prevalence of this dis-ease demands identification of its etiology. The science of proteomics can be used to identify cardiac specific proteins. The subsequent over expression or under expression of these pro-teins can be utilized as targets not only for therapeutical interventions but also for identi-fying molecular signatures for Cardiac diseases. In context of a number of studies which have shown that the specificity of serum biomarkers like troponin (cTnI and cTnT) are questionable as they may also appear in serum in pathologi-cal conditions other than cardiac dysfunction, the search of a specific marker for cardiac arrest becomes imperative. In this study protein pro-filing of cardiac arrest patients was performed after its quantification through Bradford assay. SDS-PAGE and 2 DE techniques were used as to characterize proteins. The samples of the pa-tients prior to characterizing of proteins were subjected to lipid and cardiac enzymes profiling. The results of these investigations have shown an increase in almost all of these parameters by many folds from that of normal values. In addi-tion to this the samples were found out to be positive for troponin T which strongly confirms the incidence of the cardiac arrest. The results of SDS-PAGE exhibited the induction of three proteins of 100 kDa, 97 kDa and of 66 kDa with 100 kDa as the most highly expressed protein. In addition to that SDS-PAGE gels have shown the down regulation of 45 kDa protein, again indi-cating the changes as a result of cardiac arrest. 2DE gel patterns of cardiac arrest samples demonstrated higher number of protein spots as compare to control in the alkaline range, which might suggest their role in cardiac dysfunction. Therefore it can be concluded that this study may pave the grounds for identification of such proteins which can serve not only as potential therapeutical targets but also as candidate markers for accurate diagnosis of the disease.