Markers for Early Detection of Cardiac Diseases

2D-Bio-FETs for sensitive detection of cardiovascular diseases

The biosensing industry has seen exponential growth in the past decade. Impact of biosensors in the current scenario cannot be overlooked. Cardiovascular diseases (CvDs) have been recognized as one of the major causes for millions of deaths globally. This mortality can be minimized by early and accurate detection/diagnosis of CvDs with the help of biosensing devices. This also presents a global market opportunity for the development of biosensors for CvDs. A vast variety of biosensing methods and devices have been developed for this problem. Most of commercially available platforms for CvD detection rely on optical (fluorometric and colorimetric analysis) techniques using serum biomarkers since optical testing is the gold standard in medical diagnosis. Field effect transistors-based biosensors, termed as Bio-FETs, are the upcoming devices for blood or serum analyte detection due to excellent sensitivity, low operational voltage, handheld device structure and simple chip-based operation. Further, the discovery of two dimensional (2D) materials and their integration with conventional FETs has improved the overvoltage problem, sensitivity and strict operating conditions as compared to conventional FETs. Graphene-FETs based biosensing devices have been proven as promising candidates due to their attractive properties. Despite the severe threat of CvDs which has further increased in post-covid era, the Bio-FET sensor studies in literature are still rare. In this review, we aim to provide a comprehensive view of all the multidisciplinary concepts related to 2D-BioFETs for CvDs. A critical review of the different platforms has been covered with detailed discussions of related studies to provide a clear concept and present status of 2D-BioFETs based CvD biosensors.

Heme Protein Binding of Sulfonamide Compounds: A Correlation Study by Spectroscopic, Calorimetric, and Computational Methods

Protein-ligand interaction studies are useful to determine the molecular mechanism of the binding phenomenon, leading to the establishment of the structure-function relationship. Here, we report the binding of well-known antibiotic sulfonamide drugs (sulfamethazine, SMZ; and sulfadiazine, SDZ) with heme protein myoglobin (Mb) using spectroscopic, calorimetric, ζ potential, and computational methods. Formation of a 1:1 complex between the ligand and Mb through well-defined equilibrium was observed. The binding constants obtained between Mb and SMZ/SDZ drugs were on the order of 104 M-1. SMZ with two additional methyl (-CH3) substitutions has higher affinity than SDZ. Upon drug binding, a notable loss in the helicity (via circular dichroism) and perturbation of the three-dimensional (3D) protein structure (via infrared and synchronous fluorescence experiments) were observed. The binding also indicated the dominance of non-polyelectrolytic forces between the amino acid residues of the protein and the drugs. The ligand-protein binding distance signified high probability of energy transfer between them. Destabilization of the protein structure upon binding was evident from differential scanning calorimetry results and ζ potential analyses. Molecular docking presented the best probable binding sites of the drugs inside protein pockets. Thus, the present study explores the potential binding characteristics of two sulfonamide drugs (with different substitutions) with myoglobin, correlating the structural and energetic aspects.

Simultaneous measurement method of erythrocyte sedimentation rate and erythrocyte deformability in resource-limited settings

OBJECTIVE

The individual effects of plasma and red blood cells (RBCs) on the biophysical properties of blood can be monitored by measuring the erythrocyte sedimentation rate (ESR) and RBC deformability simultaneously. However, the previous methods require bulky and expensive facilities (i.e. microscope, high-speed camera, and syringe pump) to deliver blood or capture blood flows.

APPROACH

To resolve these issues, a simple method for sequential measurement of the ESR and RBC deformability is demonstrated by quantifying the cell-free volume (V _CF ), cell-rich volume (V _CR ), and blood volume (V _B ) inside an air-compressed syringe (ACS). A microfluidic device consists of multiple micropillar channels, an inlet, and outlet. After the ACS is filled with air (V _air   =  0.4 ml) and a blood sample (V _B   =  0.6 ml, hematocrit  =  30%) sequentially, the ACS is fitted into the inlet. The cavity inside the ACS is compressed to V _comp   =  0.4 ml after closing the outlet with a stopper. A smartphone camera is employed to capture variations in the V _CF , V _CR , and V _B inside the ACS. The ESR index suggested in this study (ESR _PM ) is obtained by dividing the V _CF (t  =  t ₁) with an elapse of t ₁. By removing the stopper, ΔV _B (ΔV _B   =  V _B [t  =  t ₁]  -  V _B ) is obtained and fitted as a two-term exponential model ([Formula: see text]. As a performance demonstration, the proposed method is employed to detect an ESR-enhanced blood sample, homogeneous hardened blood sample, and heterogeneous blood sample.

MAIN RESULTS

From the experimental results, it is found that the proposed method has the ability to detect various bloods by quantifying the ESR _PM and two coefficients (a, b) simultaneously.

SIGNIFICANCE

In conclusion, the present method can be effectively used to measure the ESR and RBC deformability in resource-limited settings.

Microfluidic-Based Technique for Measuring RBC Aggregation and Blood Viscosity in a Continuous and Simultaneous Fashion

Hemorheological properties such as viscosity, deformability, and aggregation have been employed to monitor or screen patients with cardiovascular diseases. To effectively evaluate blood circulating within an in vitro closed circuit, it is important to quantify its hemorheological properties consistently and accurately. A simple method for measuring red blood cell (RBC) aggregation and blood viscosity is proposed for analyzing blood flow in a microfluidic device, especially in a continuous and simultaneous fashion. To measure RBC aggregation, blood flows through three channels: the left wide channel, the narrow channel and the right wide channel sequentially. After quantifying the image intensity of RBCs aggregated in the left channel () and the RBCs disaggregated in the right channel (), the RBC aggregation index (AIPM) is obtained by dividing by . Simultaneously, based on a modified parallel flow method, blood viscosity is obtained by detecting the interface between two fluids in the right wide channel. RBC aggregation and blood viscosity were first evaluated under constant and pulsatile blood flows. AIPM varies significantly with respect to blood flow rate (for both its amplitude and period) and the concentration of the dextran solution used. According to our quantitative comparison between the proposed aggregation index (AIPM) and the conventional aggregation index (AICM), it is found that AIPM provides consistent results. Finally, the suggested method is employed to obtain the RBC aggregation and blood viscosity of blood circulating within an in vitro fluidic circuit. The experimental results lead to the conclusion that the proposed method can be successfully used to measure RBC aggregation and blood viscosity, especially in a continuous and simultaneous fashion.

Selective Recognition of Myoglobin in Biological Samples Using Molecularly Imprinted Polymer-Based Affinity Traps

The current work demonstrates the design, characterization, and preparation of molecularly imprinted microspheres for the selective detection of myoglobin in serum samples. The suspension polymerization approach was applied for the preparation of myoglobin imprinted microspheres. For this purpose, N-methacryloylamino folic acid-Nd3+ (MAFol- Nd3+) was chosen as the complex functional monomer. The optimization studies were performed changing the medium pH, temperature, and myoglobin concentration. pH 7.0 was determined as the optimum value where the prepared imprinted microspheres displayed maximum binding for myoglobin. The maximum binding capacity was achieved as 623 mgg-1. In addition, the selectivity studies were conducted. The results confirmed that the imprinted microspheres showed great selectivity towards myoglobin in the existence of hemoglobin, cytochrome c, and lysozyme which were chosen as potentially competing proteins.

Periodic and simultaneous quantification of blood viscosity and red blood cell aggregation using a microfluidic platform under in-vitro closed-loop circulation

To evaluate variations of blood circulating in closed loops, hemorheological properties including blood viscosity and red blood cells (RBCs) are quantitatively measured with independent in-vitro instruments after collecting blood from a closed loop. But, most previous methods require periodic blood collections which induce several problems such as geometric differences between the fluidic channel and the in-vitro method, hemodilution, storage time, and unspecific blood flow rates. To resolve these issues, in this study, blood viscosity and RBC aggregation of blood circulating within a closed loop are measured with a microfluidic platform periodically and simultaneously. To demonstrate the proposed method, in-vitro closed-loop circulation is established by connecting several components (peristaltic pump, air compliance unit, fluid divider, and reservoir) in series. In addition, to measure blood viscosity and RBC aggregation, a microfluidic platform composed of a microfluidic device, pinch valve, and syringe pump is created. During each period, blood viscosity and RBC aggregation are measured by monitoring blood flow at constant blood flow, and image intensity at stationary blood flow. The proposed method is first employed to evaluate the effect of hematocrits and dextran concentrations on the RBC aggregation and blood viscosity by using a syringe pump (i.e., specific blood flow-rate). The method is then applied to detect the blood viscosity and RBC aggregation under in-vitro closed-loop circulation (i.e., unspecific blood flow-rate). From these experimental demonstrations, it is found that the suggested method can be effectively used to monitor the RBC aggregation and blood viscosity under in-vitro closed-loop circulation. Since this method does not require periodic collection from closed-loop circulation or an additional procedure for estimating blood flow-rate with a syringe pump, it will be effectively used to monitor variations of blood circulating in extracorporeal bypass loops.

Microfluidic-Based Measurement Method of Red Blood Cell Aggregation under Hematocrit Variations

Red blood cell (RBC) aggregation and erythrocyte sedimentation rate (ESR) are considered to be promising biomarkers for effectively monitoring blood rheology at extremely low shear rates. In this study, a microfluidic-based measurement technique is suggested to evaluate RBC aggregation under hematocrit variations due to the continuous ESR. After the pipette tip is tightly fitted into an inlet port, a disposable suction pump is connected to the outlet port through a polyethylene tube. After dropping blood (approximately 0.2 mL) into the pipette tip, the blood flow can be started and stopped by periodically operating a pinch valve. To evaluate variations in RBC aggregation due to the continuous ESR, an EAI (Erythrocyte-sedimentation-rate Aggregation Index) is newly suggested, which uses temporal variations of image intensity. To demonstrate the proposed method, the dynamic characterization of the disposable suction pump is first quantitatively measured by varying the hematocrit levels and cavity volume of the suction pump. Next, variations in RBC aggregation and ESR are quantified by varying the hematocrit levels. The conventional aggregation index (AI) is maintained constant, unrelated to the hematocrit values. However, the EAI significantly decreased with respect to the hematocrit values. Thus, the EAI is more effective than the AI for monitoring variations in RBC aggregation due to the ESR. Lastly, the proposed method is employed to detect aggregated blood and thermally-induced blood. The EAI gradually increased as the concentration of a dextran solution increased. In addition, the EAI significantly decreased for thermally-induced blood. From this experimental demonstration, the proposed method is able to effectively measure variations in RBC aggregation due to continuous hematocrit variations, especially by quantifying the EAI.

Detection of the inflammation biomarker C-reactive protein in serum samples: towards an optimal biosensor formula

The development of an electrochemical immunosensor for the biomarker, C-reactive protein (CRP), is reported in this work. CRP has been used to assess inflammation and is also used in a multi-biomarker system as a predictive biomarker for cardiovascular disease risk. A gold-based working electrode sensor was developed, and the types of electrode printing inks and ink curing techniques were then optimized. The electrodes with the best performance parameters were then employed for the construction of an immunosensor for CRP by immobilizing anti-human CRP antibody on the working electrode surface. A sandwich enzyme-linked immunosorbent assay (ELISA) was then constructed after sample addition by using anti-human CRP antibody labelled with horseradish peroxidase (HRP). The signal was generated by the addition of a mediator/substrate system comprised of 3,3,5',5'-Tetramethylbenzidine dihydrochloride (TMB) and hydrogen peroxide (H2O2). Measurements were conducted using chronoamperometry at -200 mV against an integrated Ag/AgCl reference electrode. A CRP limit of detection (LOD) of 2.2 ng·mL(-1) was achieved in spiked serum samples, and performance agreement was obtained with reference to a commercial ELISA kit. The developed CRP immunosensor was able to detect a diagnostically relevant range of the biomarker in serum without the need for signal amplification using nanoparticles, paving the way for future development on a cardiac panel electrochemical point-of-care diagnostic device.

Electrochemical enzyme-linked immunosorbent assay (ELISA) for α-fetoprotein based on glucose detection with multienzyme-nanoparticle amplification

Since glucose biosensors are one of the most popular and widely used point-of-care testing devices, a novel electrochemical enzyme-linked immunosorbent assay (ELISA) for protein biomarkers has been developed based on a glucose detection strategy. In this study, α-fetoprotein (AFP) was used as the target protein. An electrochemical ELISA system was constructed using anti-AFP antibodies immobilized on microwell plates as the capture antibody (Ab1) and multi-label bioconjugates as signal tracer. The bioconjugates were synthesized by attaching glucoamylase and the secondary anti-AFP antibodies (Ab2) to gold nanoparticles (AuNPs). After formation of the sandwich complex, the Ab2-glucoamylase-AuNPs conjugates converted starch into glucose in the presence of AFP. The concentration of AFP can be calculated based on the linear relation between AFP and glucose, the concentration of which can be detected by the glucose biosensor. When the AFP concentration ranged from 0.05 to 100 ng/mL, a linear calibration plot (i (µA) = 13.62033 - 2.86252 logCAFP (ng/mL), r = 0.99886) with a detection limit of 0.02 ng/mL was obtained under optimal conditions. The electrochemical ELISA developed in this work shows acceptable stability and reproducibility, and the assay for AFP spiked in human serum also shows good recovery (97.0%-104%). This new method could be applied for detecting any protein biomarker with the corresponding antibodies.

Examination of serum pregnancy-associated plasma protein A clinical value in acute coronary syndrome prediction and monitoring

INTRODUCTION

Chronic vascular inflammatory process promotes and intensifies all atherogenic events. The aim of this research was to estimate the clinical value of pregnancy-associated plasma protein A (PAPP-A) measurement associated with plaque destabilization and rupture in prediction and monitoring of acute coronary syndromes (ACS) as well as to assess the predictive value of this biomarker in comparison to traditional myocardial infarction (MI) risk markers.

MATERIAL AND METHODS

The study included 119 patients in 2 investigated groups and one control group. PAPP-A assay was performed using manual ELISA kit, DRG. All other parameters were determined using automatic analyzers: Olympus and Dade Behring.

RESULTS

A statistically significant difference between PAPP-A concentration median value was found in the investigated group MI individuals' serum and control group individuals' serum (11.42 ng/ml and 7.22 ng/ml respectively, p = 0.003). PAPP-A assay had the highest specificity (83.3%) and sensitivity (53.8%), and therefore the highest clinical value. In patients with clinically and laboratory confirmed MI we proved that PAPP-A serum level is a clinically useful biomarker in ACS prediction, better than C-reactive protein (hsCRP) and fibrinogen (FBG) level.

CONCLUSIONS

The highest diagnostic efficiency for ACS prediction was proved for simultaneous panel assays consisting of 2-3 parameters (PAPP-A - hsCRP, PAPP-A - FBG, PAPP-A - hsCRP - FBG), while PAPP-A itself does not show characteristics necessary for it to be used as a biomarker for MI dynamic monitoring. It is possible that prothrombotic component is mainly responsible for repeated major adverse cardiac events, more than inflammatory process.

Positive correlation between pregnancy-associated plasma protein-A level and OX40 ligand expression in patients with acute coronary syndromes

OBJECTIVE

Increasing evidence show that serum pregnancy-associated plasma protein-A (PAPP-A) and OX40 ligand (OX40L) expression have been implicated in acute coronary syndromes (ACS). We investigated the relationship between PAPP-A level and OX40L in serum and membrane-bound OX40L in patients with ACS.

METHODS

The present study included normal controls (n=30), patients with stable angina (SA) (n=60) and patients with ACS, including unstable angina (UA) (n=50) and acute myocardial infarction (AMI) (n=30). Serum concentrations of PAPP-A and soluble OX40L (sOX40L) were determined with Elisa, whereas the expression of OX40L on monocytes were analyzed with flow cytometry.

RESULTS

The expression of OX40L in peripheral monocytes in patients with UA [25.6±5.5 mean fluorescence intensity (MFI)] and AMI (29.4±6.3MFI) were significantly higher than those in patients with SA (10.6±2.8MFI) and controls (11.1±3.5MFI). Both sOX40L and PAPP-A in patients with UA (15.7±4.9ng/mL, 25.4±6.8μg/mL, respectively) and AMI (17.1±5.3ng/mL, 26.3±5.6μg/mL, respectively) were significantly higher than those in patients with SA (3.4±1.4ng/mL, 9.6±2.1μg/mL, respectively) and controls (3.9±1.3ng/mL, 8.5±2.8μg/mL, respectively) (P<0.001). Interestingly, a positive correlation was found between sOX40L, membrane-bound OX40L and serum PAPP-A levels (r(1)=0.54, r(2)=0.51; P<0.0001). Both serum and membrane-bound OX40L and PAPP-A levels significantly correlated with complex coronary stenosis (r(1)=0.56, r(2)=0.55, r(3)=0.40; P<0.001).

CONCLUSION

PAPP-A level was significantly related to soluble and membrane-bound OX40L in patients with ACS. Enhanced level of serum PAPP-A and sOX40L might represent a prognostic marker for coronary disease activity.

Placental growth factor as short-term predicting biomarker in acute coronary syndrome patients with non-ST elevation myocardial infarction

OBJECTIVES

The relevance of placental growth factor was analyzed at the admission of patients with acute coronary syndrome (ACS) without ST elevation in prognosis of fatal outcome after 30 days.

METHODS

We collected blood samples from 102 ACS patients admitted to the coronary unit with acute chest pain manifesting within the last 12 hours.

RESULTS

In all 102 admitted patients, higher values of placental growth factor (PLGF; >13.2 ng/L, average value) indicated a higher risk of fatal outcome (hazard ratio [HR] 2.28, 95% confidence interval [CI] 1.21- 4.76, P = 0.0125). PLGF is an important independent prognostic marker (adjusted HR 2.35, 95% CI 1.98-4.61, P = 0.1338), and this was shown in a multiparameter model, which involved other statistically important markers of relative risk (age >65, gender, and estimated glomerular filtration rate [eGFR]).

CONCLUSION

PLGF levels measured at 12 hours of symptom onset and 30 days later may independently predict fatal outcome in patients with ACS without ST elevation.

Cardiac biomarkers - the old and the new: a review

Biomarkers are biological parameters that can be objectively measured and quantified as indicators of normal biologic processes, pathogenic processes, or responses to a therapeutic intervention. Typically thought of as disease process screening, diagnosing, or monitoring tools, biomarkers may also be used to determine disease susceptibility and eligibility for specific therapies. Cardiac biomarkers are protein components of cell structures that are released into circulation when myocardial injury occurs. They play a pivotal role in the diagnosis, risk stratification, and treatment of patients with chest pain and suspected acute coronary syndrome and those with acute exacerbations of heart failure. Cardiac markers are central to the new definition of acute myocardial infarction put forward by the American College of Cardiology and the European Society of Cardiology. Active investigation has brought forward an increasingly large number of novel candidate markers but few have withstood the test of time and become integrated into contemporary clinical care because of their readily apparent diagnostic, prognostic, or therapeutic utility.

Future developments in chest pain diagnosis and management

Much of the focus of research on patients with chest pain is directed at technological advances in the diagnosis and management of acute coronary syndrome (ACS), pulmonary embolism (PE), and acute aortic dissection (AAD), despite there being no significant difference at 4 years as regards mortality, ongoing chest pain, and quality of life between patients presenting to the emergency department with noncardiac chest pain and those with cardiac chest pain. This article examines future developments in the diagnosis and management of patients with suspected ACS, PE, AAD, gastrointestinal disease, and musculoskeletal chest pain.

The use of proteomics to identify novel therapeutic targets for the treatment of disease

The completion of the Human Genome Project has revealed a multitude of potential avenues for the identification of therapeutic targets. Extensive sequence information enables the identification of novel genes but does not facilitate a thorough understanding of how changes in gene expression control the molecular mechanisms underlying the development and regulation of a cell or the progression of disease. Proteomics encompasses the study of proteins expressed by a population of cells, and evaluates changes in protein expression, post-translational modifications, protein interactions, protein structure and splice variants, all of which are imperative for a complete understanding of protein function within the cell. From the outset, proteomics has been used to compare the protein profiles of cells in healthy and diseased states and as such can be used to identify proteins associated with disease development and progression. These candidate proteins might provide novel targets for new therapeutic agents or aid the development of assays for disease biomarkers. This review provides an overview of the current proteomic techniques available and focuses on their application in the search for novel therapeutic targets for the treatment of disease.

Development of a method to measure plasma and whole blood choline by liquid chromatography tandem mass spectrometry

Background

Current gold standard markers for myocardial damage are troponins I and T, which are both sensitive and specific for the detection of myocardial infarction, but require up to 6 h to become reliably elevated in serum. Investigation into markers with potential to identify patients with early ischaemic changes is therefore intense. Choline is reported to be prognostic in patients presenting with acute coronary syndromes via its release from ischaemic cell membranes.

Methods

Liquid chromatography tandem mass spectrometry was used to develop a method to quantitate choline in plasma and blood. The method involves addition of a deuterated internal standard to an aliquot of plasma or blood followed by organic solvent addition, which precipitates the proteins in the sample. Preparation was carried out directly into a 96-deep-well plate. Chromatography of choline used a strong cation exchange column and separation used a Waters Atlantis dC18 analytical column positioned directly before the mass spectrometer source, allowing on-line preanalytical clean up of the sample.

Results

The lower limit of quantitation was 0.38 μmol/L, linearity was observed up to 754 μmol/L, with a working concentration range of 0.38–224 μmol/L, inter- and intra-assay coefficients of variation were <6% and <4%, respectively. Samples were stable throughout five freeze–thaw cycles and recovery was between 94% and 114%.

Conclusions

The assay was successfully validated in accordance with FDA guidelines and is suitable for quantitation of choline in research and clinical settings.

Emergency physician high pretest probability for acute coronary syndrome correlates with adverse cardiovascular outcomes

OBJECTIVES

The value of unstructured physician estimate of risk for disease processes, other than acute coronary syndrome (ACS), has been demonstrated. The authors sought to evaluate the predictive value of unstructured physician estimate of risk for ACS in emergency department (ED) patients without obvious initial evidence of a cardiac event.

METHODS

This was a post hoc secondary analysis of the Internet Tracking Registry for Acute Coronary Syndromes (i*trACS), a prospectively collected multicenter data registry of patients over the age of 18 years presenting to the ED with symptoms of ACS between 1999 and 2001. In this registry, following patient history, physical exam, and electrocardiogram (ECG), the unstructured treating physician estimate of risk was recorded. A 30-day follow-up and a medical record review were used to determine rates of adverse cardiac events, death, myocardial infarction (MI), or revascularization procedure. The analysis included all patients with nondiagnostic ECG changes, normal initial biomarkers, and a non-MI initial impression from the registry and excluded those without complete data or who were lost to follow-up. Data were stratified by unstructured physician risk estimate: noncardiac, low risk, high risk, or unstable angina.

RESULTS

Of 15,608 unique patients in the registry, 10,145 met inclusion/exclusion criteria. Patients were defined as having unstable angina in 6.0% of cases; high risk, 23.5% of cases; low risk, 44.2%; and noncardiac, 26.3% of cases. Adverse cardiac event rates had an inverse relationship, decreasing from 22.0% (95% confidence interval [CI] = 18.8% to 25.6%) for unstable angina, 10.2% (95% CI = 9.0% to 11.5%) for those stratified as high risk, 2.2% (95% CI = 1.8% to 2.6%) for low risk, and to 1.8% (95% CI = 1.4% to 2.4%) for noncardiac. The relative risk (RR) of an adverse cardiac event for those with an initial label of unstable angina compared to those with a low-risk designation was 10.2 (95% CI = 8.0 to 13.0). The RR of an event for those with a high-risk initial impression compared to those with a low-risk initial impression was 4.7 (95% CI = 3.8 to 5.9). The risk of an event among those with a low-risk initial impression was the same as for those with a noncardiac initial impression (RR = 0.83, 95% CI = 0.6 to 1.2).

CONCLUSIONS

In ED patients without obvious initial evidence of a cardiac event, unstructured emergency physician (EP) estimate of risk correlates with adverse cardiac outcomes.

Computational prediction models for early detection of risk of cardiovascular events using mass spectrometry data

Early prediction of the risk of cardiovascular events in patients with chest pain is critical in order to provide appropriate medical care for those with positive diagnosis. This paper introduces a computational methodology for predicting such events in the context of robust computerized classification using mass spectrometry data of blood samples collected from patients in emergency departments. We applied the computational theories of statistical and geostatistical linear prediction models to extract effective features of the mass spectra and a simple decision logic to classify disease and control samples for the purpose of early detection. While the statistical and geostatistical techniques provide better results than those obtained from some other methods, the geostatistical approach yields superior results in terms of sensitivity and specificity in various designs of the data set for validation, training, and testing. The proposed computational strategies are very promising for predicting major adverse cardiac events within six months.

Proteomics and heart disease: identifying biomarkers of clinical utility

Cardiovascular disease is the leading cause of mortality and morbidity in the industrialized world. Total worldwide deaths due to this disease are currently estimated at 17 million per year, and this number is expected to increase over the next several decades. To address this epidemic, a major effort has begun to develop new cardiovascular disease markers through the use of proteomic analysis, the global study of proteins. This review discusses strategies, recent technological advances and other issues in plasma/serum biomarker discovery for cardiovascular diseases. Emphasis lies on the needs for standardizing specimen collection, methods for reducing plasma proteome complexity to subproteomes, selection of appropriate technology platforms and strategies to evaluate candidates by multiplexed immune assays. The overall goal of this effort is to identify serum biomarkers for diagnosis, therapeutic monitoring and risk stratification of cardiovascular diseases.

Sixty-four–slice computed tomographic coronary angiography: will the “triple rule out” change chest pain evaluation in the ED?

Sixty-four-slice computed tomographic (CT) coronary angiography is a new technique for the noninvasive visualization of the coronary arteries. It enables noninvasive detection of coronary plaque and determination of severity without instrumentation of the heart. Although not yet commonly used in the emergency department setting, it stands poised to dramatically change the way that patients with chest pain are evaluated. In addition to evaluation of the coronary arteries, CT angiography has long been used to evaluate patients for other dangerous causes of chest pain such as aortic dissection and pulmonary embolus. Although these new scanners excel at all of these diagnostic modalities, the true excitement is in the possibility of combining several different protocols into one, allowing for multiple causes of chest pain to be "ruled out" simultaneously. This article describes the current state of the art of cardiac CT, current state of research, and current areas of controversy.

Measurement and clinical significance of circulating PAPP-A in ACS patients

BACKGROUND

The rupture of coronary atherosclerotic plaque and subsequent thrombus formation are major events underlying acute coronary syndromes (ACS). Pregnancy associated plasma protein A (PAPP-A), a biomarker of plaque rupture, has been studied in patients with ACS. This review aimed to provide an overview of clinical utility of PAPP-A in ACS patients and analytical issues adhering to immunological PAPP-A measurement.

METHODS

The literature relating to PAPP-A in ACS, the molecular structure and immunodetection of PAPP-A was reviewed. PubMed was used to search the relevant articles published from 1974 to 2006.

RESULTS

Higher PAPP-A concentrations have been found in patients with ACS than in patients with stable angina and subjects without coronary artery disease. Elevated PAPP-A concentrations have also been shown to associate with adverse cardiac events in ACS patients. The prognostic value of PAPP-A appears to be independent of cardiac troponins. Noteworthy, the PAPP-A form that accounts for increase in ACS is uncomplexed with the proform of eosinophil major basic protein (proMBP). However, PAPP-A assays applied in clinical studies published thus far detect total PAPP-A. Consequently, the clinical value may be non-optimal when total PAPP-A is measured in ACS patients. In addition, the clinical value can also be affected by the analytical factors that exert an effect on the performance of PAPP-A assays.

CONCLUSIONS

PAPP-A appears to be a very promising biomarker useful in the clinical management of ACS patients. However, more prospective and interventional studies with carefully established immunoassays are required to validate its clinical utility.

Cardiac markers and their point-of-care testing for diagnosis of acute myocardial infarction

Acute myocardial infarction (AMI) is the world's leading cause of mortality and morbidity. Therefore, quick and reliable diagnostics of AMI is extremely critical. Compared to the traditionally used central laboratory tests (CLT), which can be time-consuming and expensive, point-of-care testing (POCT) for AMI-indicative cardiac markers provides a convenient means for rapid diagnostic assays to be performed at the site of patient care delivery. In this article, the etiology and diagnosis of AMI are introduced, and some typical cardiac markers and their clinical applications are reviewed. Furthermore, the various POC cardiac marker devices that are currently available, the benefits of using cardiac marker POC assays, and challenges that cardiac marker POCT are facing are also discussed.