Development of a sandwich enzyme-linked immunosorbent assay for the determination of human heart type fatty acid-binding protein in plasma and urine by using two different monoclonal antibodies specific for human heart fatty acid-binding protein

Temporal patterns of cytokine and injury biomarkers in hospitalized COVID-19 patients treated with methylprednisolone

Background

The novel coronavirus disease 2019 (COVID-19) presents with complex pathophysiological effects in various organ systems. Following the COVID-19, there are shifts in biomarker and cytokine equilibrium associated with altered physiological processes arising from viral damage or aggressive immunological response. We hypothesized that high daily dose methylprednisolone improved the injury biomarkers and serum cytokine profiles in COVID-19 patients.

Methods

Injury biomarker and cytokine analysis was performed on 50 SARS-Cov-2 negative controls and 101 hospitalized severe COVID-19 patients: 49 methylprednisolone-treated (MP group) and 52 placebo-treated serum samples. Samples from the treated groups collected on days D1 (pre-treatment) all the groups, D7 (2 days after ending therapy) and D14 were analyzed. Luminex assay quantified the biomarkers HMGB1, FABP3, myoglobin, troponin I and NTproBNP. Immune mediators (CXCL8, CCL2, CXCL9, CXCL10, TNF, IFN-γ, IL-17A, IL-12p70, IL-10, IL-6, IL-4, IL-2, and IL-1β) were quantified using cytometric bead array.

Results

At pretreatment, the two treatment groups were comparable demographically. At pre-treatment (D1), injury biomarkers (HMGB1, TnI, myoglobin and FABP3) were distinctly elevated. At D7, HMGB1 was significantly higher in the MP group (p=0.0448) compared to the placebo group, while HMGB1 in the placebo group diminished significantly by D14 (p=0.0115). Compared to healthy control samples, several immune mediators (IL-17A, IL-6, IL-10, MIG, MCP-1, and IP-10) were considerably elevated at baseline (all p≤0.05). At D7, MIG and IP-10 of the MP-group were significantly lower than in the placebo-group (p=0.0431, p=0.0069, respectively). Longitudinally, IL-2 (MP-group) and IL-17A (placebo-group) had increased significantly by D14. In placebo group, IL-2 and IL-17A continuously increased, as IL-12p70, IL-10 and IP-10 steadily decreased during follow-up. The MP treated group had IL-2, IFN-γ, IL-17A and IL-12p70 progressively increase while IL-1β and IL-10 gradually decreased towards D14. Moderate to strong positive correlations between chemokines and cytokines were observed on D7 and D14.

Conclusion

These findings suggest MP treatment could ameliorate levels of myoglobin and FABP3, but appeared to have no impact on HMGB1, TnI and NTproBNP. In addition, methylprednisolone relieves the COVID-19 induced inflammatory response by diminishing MIG and IP-10 levels. Overall, corticosteroid (methylprednisolone) use in COVID-19 management influences the immunological molecule and injury biomarker profile in COVID-19 patients.

Electroanalytical point-of-care detection of gold standard and emerging cardiac biomarkers for stratification and monitoring in intensive care medicine - a review

Determination of specific cardiac biomarkers (CBs) during the diagnosis and management of adverse cardiovascular events such as acute myocardial infarction (AMI) has become commonplace in emergency department (ED), cardiology and many other ward settings. Cardiac troponins (cTnT and cTnI) and natriuretic peptides (BNP and NT-pro-BNP) are the preferred biomarkers in clinical practice for the diagnostic workup of AMI, acute coronary syndrome (ACS) and other types of myocardial ischaemia and heart failure (HF), while the roles and possible clinical applications of several other potential biomarkers continue to be evaluated and are the subject of several comprehensive reviews. The requirement for rapid, repeated testing of a small number of CBs in ED and cardiology patients has led to the development of point-of-care (PoC) technology to circumvent the need for remote and lengthy testing procedures in the hospital pathology laboratories. Electroanalytical sensing platforms have the potential to meet these requirements. This review aims firstly to reflect on the potential benefits of rapid CB testing in critically ill patients, a very distinct cohort of patients with deranged baseline levels of CBs. We summarise their source and clinical relevance and are the first to report the required analytical ranges for such technology to be of value in this patient cohort. Secondly, we review the current electrochemical approaches, including its sub-variants such as photoelectrochemical and electrochemiluminescence, for the determination  of important CBs highlighting the various strategies used, namely the use of micro- and nanomaterials, to maximise the sensitivities and selectivities of such approaches. Finally, we consider the challenges that must be overcome to allow for the commercialisation of this technology and transition into intensive care medicine.

Electrochemical immunosensor development based on core-shell high-crystalline graphitic carbon nitride@carbon dots and Cd0.5Zn0.5S/d-Ti3C2Tx MXene composite for heart-type fatty acid-binding protein detection

Acute myocardial infarction (AMI) is a significant health problem owing to its high mortality rate. Heart-type fatty acid-binding protein (h-FABP) is an important biomarker in the diagnosis of AMI. In this work, an electrochemical h-FABP immunosensor was developed based on Cd_0.5Zn_0.5S/d-Ti₃C₂T_x MXene (MXene: Transition metal carbide or nitride) composite as signal amplificator and core-shell high-crystalline graphitic carbon nitride@carbon dots (hc-g-C₃N₄@CDs) as electrochemical sensor platform. Firstly, a facile calcination technique was applied to the preparation of hc-g-C₃N₄@CDs and immobilization of primary antibody was performed on hc-g-C₃N₄@CDs surface. Then, the conjugation of the second antibody to Cd_0.5Zn_0.5S/d-Ti₃C₂T_x MXene was carried out by strong π-π and electrostatic interactions. The prepared electrochemical h-FABP immunosensor was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), x-ray diffraction (XRD) method, Fourier-transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The prepared electrochemical h-FABP immunosensor indicated a good sensitivity with detection limit (LOD) of 3.30 fg mL^-1 in the potential range +0.1 to +0.5 V. Lastly, low-cost, satisfactory stable, and environmentally friendly immunosensor was presented for the diagnosis of acute myocardial infarction.

Promising Novel Biomarkers in Cardiovascular Diseases

Cardiovascular diseases remain the most common causes of death globally, according to the World Health Organization. In recent years, a great number of biomarkers have been investigated, whereas only some have gained value in the diagnosis, prognosis, and risk stratification of different cardiovascular illnesses. As numerous studies have investigated the diagnostic yield of novel biomarkers in various disease entities every year, this review aims to provide an overview of the current status of four promising representatives. In particular, this manuscript refers to soluble suppression of tumorigenicity 2 (sST2), heart-type fatty acid binding protein (H-FABP), growth differentiation factor (GDF-15) and soluble urokinase-type plasminogen activator receptor (suPAR). These markers are of special interest as they are thought to provide an accurate estimate of cardiovascular risk in certain patient populations, especially those with pre-existing diseases, such as obesity or diabetes mellitus. We sought to give an overview of their function, individual diagnostic and predictive value and determination in the laboratory. A review of the literature regarding the aforementioned cardiovascular biomarkers yielded manifold results with respect to their individual diagnostic and prognostic value. Yet, the clinical relevance of these findings remains unclear, warranting further studies to identify their optimal use in clinical routine.

A highly sensitive electrochemiluminescence immunosensor for h-FABP determination based on self-enhanced luminophore coupled with ultrathin 2D nickel metal-organic framework nanosheets

In this work, a novel ECL immunosensor based on self-enhanced luminophore and ultrathin 2D nickel MOF nanosheets was fabricated for sensitive and specific detection of h-FABP. Initially, the porous ultrathin Ni-TCPP (Fe) nanosheets with high specific surface area and plentiful active sites were newly synthesized, which could enhance ECL signal of luminol by the superior peroxidase mimics activity towards H₂O₂ decomposition. Then, PEI and luminol were simultaneously immobilized on Ni-TCPP (Fe) nanosheets to construct self-enhanced solid state luminophore (Ni-TCPP (Fe)-PEI-Lum), possessing desirable stability and high ECL efficiency. Furthermore, poly (indole-5-carboxylic acid) (PICA) worked as substrate with outstanding conductivity and abundant binding sites to improve sensitivity. Under optimal conditions, the designed ECL immunosensor exhibited a wide dynamic range from 100 fg mL^-1 to 100 ng mL^-1 and a low detection limit of 44.5 fg mL^-1. In addition, the ECL immunosensor behaved excellent specificity and was successfully applied to detect target h-FABP protein in complex physiological matrix. Therefore, this work may provide an alternative method for biomarker detection in clinical diagnosis and expand the application potential of 2D MOF nanosheets in ECL technique.

Combined assessment of myocardial damage and electrical disturbance in chronic heart failure

AIM

To investigate feasibility of combined assessment of biochemical and electrophysiological myocardial impairment markers risk-stratifying patients with chronic heart failure (CHF).

METHODS

Serum levels of heart-type fatty acid binding protein (H-FABP) as a marker of ongoing myocardial damage and QRS duration on electrocardiogram were measured at admission in 322 consecutive patients with CHF. A prolonged QRS duration was defined as 120 ms or longer. The cut-off value for H-FABP level (4.5 ng/mL) was determined from a previous study. Patients were prospectively followed during a median follow up period of 534 d. The primary endpoint was cardiac deaths and rehospitalization for worsening CHF.

RESULTS

There were 117 primary events, including 27 cardiac deaths and 90 rehospitalizations. Patients were stratified into four groups according to H-FABP level and QRS duration (≥ 120 ms). Multivariate analysis demonstrated that high H-FABP levels [hazard ratio (HR) = 1.745, P = 0.021] and QRS prolongation (HR 1.612, P = 0.0258) were independent predictors of cardiac events. Kaplan-Meier analysis demonstrated that the combination of high H-FABP levels and QRS prolongation could be used to reliably stratify patients at high risk for cardiac events (log rank test P < 0.0001).

CONCLUSION

Combined assessment of myocardial damage and electrical disturbance can be used to risk-stratify patients with CHF.

Vancomycin modifies the expression of the agr system in multidrug-resistant Staphylococcus aureus clinical isolates

Staphylococcus aureus is an opportunistic pathogen that colonizes human hosts and causes a wide variety of diseases. Two interacting regulatory systems called agr (accessory gene regulator) and sar (staphylococcal accessory regulator) are involved in the regulation of virulence factors. The aim of this study was to evaluate the effect of vancomycin on hld and spa gene expression during the exponential and post-exponential growth phases in multidrug-resistant (MDR) S. aureus.

Methods: Antibiotic susceptibility was evaluated by the standard microdilution method. The phylogenetic profile was obtained by pulsed-field gel electrophoresis (PFGE). Polymorphisms of agr and SCCmec (staphylococcal cassette chromosome mec) were analyzed by multiplex polymerase chain reaction (PCR). The expression levels of hld and spa were analyzed by reverse transcription-PCR. An enzyme-linked immunosorbent assay (ELISA) was performed to detect protein A, and biofilm formation was analyzed via crystal violet staining.

Results: In total, 60.60% (20/33) of S. aureus clinical isolates were MDR. Half (10/20) of the MDR S. aureus isolates were distributed in subcluster 10, with >90% similarity among them. In the isolates of this subcluster, a high prevalence (100%) for the agrII and the cassette SCCmec II polymorphisms was found. Our data showed significant increases in hld expression during the post-exponential phase in the presence and absence of vancomycin. Significant increases in spa expression, protein A production and biofilm formation were observed during the post-exponential phase when the MDR S. aureus isolates were challenged with vancomycin.

Conclusion: The polymorphism agrII, which is associated with nosocomial isolates, was the most prevalent polymorphism in MDR S. aureus. Additionally, under our study conditions, vancomycin modified hld and spa expression in these clinical isolates. Therefore, vancomycin may regulate alternative systems that jointly participate in the regulation of these virulence factors.

Incremental value of heart-type fatty acid-binding protein in suspected acute myocardial infarction early after symptom onset

BACKGROUND

The early diagnosis of acute myocardial infarction (AMI) very soon after symptom onset remains a major clinical challenge, even when using high-sensitivity cardiac troponin (hs-cTnT).

METHODS AND RESULTS

We investigated the incremental value of heart-type fatty acid-binding protein (hFABP) in a pre-specified subgroup analysis of patients presenting with suspected AMI within 1 h of symptom onset to the emergency department (ED) in a multicentre study. HFABP was measured in a blinded fashion. Two independent cardiologists using all available clinical information, including hs-cTnT, adjudicated the final diagnosis. Overall, 1411 patients were enrolled, of whom 105 patients presented within 1 h of symptom onset. Of these, 34 patients (32.4%) had AMI. The diagnostic accuracy as quantified by the area under the receiver-operating characteristics curve (AUC) of hFABP was high (0.84 (95% CI 0.74-0.94)). However, the additional use of hFABP only marginally increased the diagnostic accuracy of hs-cTnT (AUC 0.88 (95% CI 0.81-0.94) for hs-cTnT alone to 0.90 (95% CI 0.83-0.98) for the combination; p=ns). After the exclusion of 18 AMI patients with ST-segment elevation, similar results were obtained. Among the 16 AMI patients without ST-segment elevation, six had normal hs-cTnT at presentation. Of these, hFABP was elevated in two (33.3%) patients.

CONCLUSIONS

hFABP does not seem to significantly improve the early diagnostic accuracy of hs-cTnT in the important subgroup of patients with suspected AMI presenting to the ED very early after symptom onset.

Circulating levels of fatty acid-binding protein family and metabolic phenotype in the general population

Objective

Fatty acid-binding proteins (FABPs) are a family of 14-15-kDa proteins, and some FABPs have been to be used as biomarkers of tissue injury by leak from cells. However, recent studies have shown that FABPs can be secreted from cells into circulation. Here we examined determinants and roles of circulating FABPs in a general population.

Methods

From the database of the Tanno-Sobetsu Study, a study with a population-based cohort design, data in 2011 for 296 subjects on no medication were retrieved, and FABP1∼5 in their serum samples were assayed.

Results

Level of FABP4, but not the other isoforms, showed a gender difference, being higher in females than in males. Levels of all FABPs were negatively correlated with estimated glomerular filtration rate (eGFR), but a distinct pattern of correlation with other clinical parameters was observed for each FABP isoform; significant correlates were alanine aminotransferase (ALT), blood pressure (BP), and brain natriuretic peptide (BNP) for FABP1, none besides eGFR for FABP2, age, BP, and BNP for FABP3, age, waist circumference (WC), BP, BNP, lipid variables, high-sensitivity C-reactive protein (hsCRP), and HOMA-R for FABP4, and age, WC, BP, ALT, BNP, and HOMA-R for FABP5. FABP4 is the most strongly related to metabolic markers among FABPs. In a multivariate regression analysis, FABP4 level was an independent predictor of HOMA-R after adjustment of age, gender, WC, BP, HDL cholesterol, and hsCRP.

Conclusions

Each FABP isoform level showed a distinct pattern of correlation with clinical parameters, although levels of all FABPs were negatively determined by renal function. Circulating FABP4 appears to be a useful biomarker for detecting pre-clinical stage of metabolic syndrome, especially insulin resistance, in the general population.

Heart type fatty acid binding protein: structure, function and biosensing applications for early detection of myocardial infarction

Heart type fatty acid binding protein (HFABP) as an early marker of cardiac injury holds a promising future with studies indicating surpassing performance as compared to myoglobin. As a plasma marker, this cytoplasmic protein owing to its small size (∼15kDa) and water solubility, appears readily in the blood-stream following cardiomyocyte damage, reaching peak levels within 6h of symptom onset. Low plasma levels of HFABP as compared to tissue levels indicate that minute amounts of the protein when released during myocardial infarction leads to a greater proportional rise. These parameters of kinetic release make it an ideal candidate for rapid assessment of acute myocardial infarction (AMI). The need for development of rapid immunoassays and immunotests so as to use HFABP as an early marker for AMI exclusion is tremendous. In the present review, we outline the various immunoassays and immunosensors developed so far for the detection of HFABP in buffer, plasma or whole blood. The principles behind the detection techniques along with their performance parameters compared to standard ELISA techniques are elucidated.

Cardiac biomarkers in the critically ill

Cardiac biomarkers have well-established roles in acute coronary syndrome and congestive heart failure. In many instances, the detection of cardiac biomarkers may aid in the diagnosis and risk assessment of critically ill patients. Despite increasing interest in the use of cardiac biomarkers in noncardiac critical illness, no clear consensus exists on how and in which settings markers should be measured. This article briefly describes what constitutes an ideal biomarker and focuses on those that have been most well studied in critical illness, specifically troponin, the natriuretic peptides, and heart-type fatty acid-binding protein.

Biochemical markers in acute coronary syndrome

Owing to their higher risk for cardiac death or ischemic complications, patients with acute coronary syndrome (ACS) must be identified from other causes of chest pain. Patients with acute coronary syndrome are divided into categories based on their electrocardiogram; those with new ST-segment elevation and those who present with ST-segment depression. The subgroups of patients with ST-segment elevation are candidates for immediate reperfusion, while fibrinolysis appears harmful for those with non-ST elevation myocardial infarction. There is increasing evidence to encourage appropriate risk stratification before deciding on a management strategy (invasive or conservative) for each patient. The TIMI, GRACE or PURSUIT risk models are recommended as useful for decisions regarding therapeutic options. Cardiac biomarkers are useful additions to these clinical tools to correctly risk stratify ACS patients. Cardiac troponin is the biomarker of choice to detect myocardial necrosis and is central to the universal definition of myocardial infarction. The introduction of troponin assays with a lower limit of detection will allow for earlier diagnosis of patients who present with chest pain. Analytical and clinical validations of these new assays are currently in progress. The question is whether the lower detection limit of the troponin assays will be able to indicate myocardial ischemia in the absence of myocardial necrosis. Previous to the development of ultrasensitive cardiac troponin assays free fatty acids unbound to albumin and ischemia modified albumin were proposed as biochemical markers of ischemia. Advances in our knowledge of the pathogenesis of acute coronary thrombosis have stimulated the development of new biomarkers. Markers of left ventricular performance (N-terminal pro-brain natriuretic peptide) and inflammation (e.g. C-reactive protein) are generally recognized as risk indicators. Studies suggest that using a number of biomarkers clinicians can risk stratify patients over a broad range of short and long term cardiac events. Nevertheless, it is still under debate as to which biomarker combination is best preferred for risk prediction. This review will focus on recent practice guidelines for the management of patients with ACS as well as current advances in cardiac biomarkers, their integration into clinical care and their diagnostic, prognostic and therapeutic utility.

H-FABP in cases of carbon monoxide intoxication admitted to the emergency room

INTRODUCTION

Carbon monoxide (CO) intoxication causes cardiovascular problems as a result of diffuse tissue hypoxia. Cardiac biochemical markers and electrocardiographic changes have been reported in CO intoxications. Human fatty acid-binding protein (H-FABP) has been recently used as a reliable marker in identifying early cardiac damage. In this prospective study, we aimed to investigate the advantages of the use of H-FABP, in evaluating the findings of myocardial ischemia in patients with CO intoxication in our region.

METHODS

Twenty four successive patients admitted to the emergency department with acute CO intoxication were included in our study. Serum traditional markers and H-FABP were also taken in the earliest period for evaluation of cardiac damage.

RESULTS

The creatinine kinase MB (CKMB) levels were positive in 11 of the patients; however, H-FABP and troponin T levels were positive in only 3 of them. One of these subjects had elevated level of H-FABP in the short-term and increasing troponin T level increasing level of troponin T during the follow-up period.

CONCLUSION

The obtained data supports the use of H-FABP, a specific indicator in identifying the cardiotoxicity of CO intoxications at an early phase.

Highly sensitive recombinant antibodies capable of reliably differentiating heart-type fatty acid binding protein from noncardiac isoforms

During recent times, heart-type fatty acid binding protein (hFABP) has gained increasing credence as a promising cardiac biomarker. This is largely due to its rapid myocardial release and subsequent clearance kinetics, which are superior to those of myoglobin and offer an earlier diagnostic window than the troponins. Realization of its full diagnostic and prognostic potential is dependent on accessibility to robust hFABP-specific assays. Here we describe a rational strategy for generation and screening of hFABP-specific avian-derived recombinant antibodies. These antibodies were confirmed to be exquisitely specific for hFABP, with no cross-reactivity observed in a representative panel of the most homologous non-heart-type FABP isoforms. All of the antibodies tested exhibited single-figure nanomolar affinities, and their analytical potential was demonstrated in a simple inhibition enzyme-linked immunosorbent assay (ELISA) format that returned an impressive limit of quantitation (LOQ) value of 1.9 ng/ml. The cumulative results underline the potential value of these antibodies as enabling reagents for use in a variety of immunodiagnostic configurations.

[Study on single nucleotide polymorphisms of H-FABP gene in sheep]

PCR-SSCP and DNA sequencing approaches were applied to assess the single nucleotide polymorphisms (SNPs) and analyze the genetic polymorphisms at partial exon 2 and intron 2 of H-FABP(Heart fatty acid-binding protein)gene, and five sheep populations that comprised of Small-Tailed Han sheep (SH, 48), Ningxia Tan sheep (Tan, 121), Tan x SH F1 (23), Poll Dorset (48) and Suffolk (24) sheep were screened in this study. The result showed: (1)four SNPs at 981(G/A), 1014(A/C) 1019(T/C) and 1058 (-/G ) and nine genotypes (AA, BB, CC, AB, AC, BC, AD, CD and BD) were detected using primer 2, the AA was the predominant genotype. A chi-square analysis suggested that the allele frequencies and genotype frequencies of H-FABP were in Hardy-Weinberg equilibrium except the Tan and Suffolk populations. Statistical analysis revealed a low polymorphism information content (PIC) in the Suffolk and Tan x SH F1 populations (PIC amp; 0.25) but an intermediate PIC in the remaining three populations (0.25 amp; PIC amp;0.50). It meant that the fragment of H-FABP had polymorphisms, which could be used as a candidate gene associated gene with phenotypic traits like intramuscular fat content in different sheep populations. (2)Three genotypes (HH, Hh and hh) determined by a SNP at 2407(T-C) were detected using primer 4. The genotype frequencies were in the order of HHHhhh. A chi-square analysis suggested that the allele frequencies and genotype frequencies of H-FABP were in Hardy-Weinberg equilibrium in the Tan and Poll Dorset populations, and the PIC values were low (PIC amp; 0.25). However, there was no polymorphisms in SH, Tan x SH F1 and Suffolk populations.

Prediction of acute cellular renal allograft rejection by urinary metabolomics using MALDI-FTMS

The present study investigated small molecule analysis of urinary samples as a noninvasive method to detect acute cellular renal allograft rejection. Matrix-assisted laser desorption/ionization Fourier transform mass spectrometry (MALDI-FTMS) was used to analyze 15 urinary samples from transplant patients with different grades of biopsy showing improved clinical acute cellular rejection (ACR) and 24 urinary samples from 8 transplant patients without evidence of rejection. Seven small molecules demonstrated highly successful diagnostic performance (m/z): 278.1 (t = 3.398, p = 0.004), 293.0 (t = 2.169, p = 0.048), 294.1 (t = 2.154, p = 0.05), 382.2 (t = 2.961, p = 0.010), 383.3 (t = 2.270, p = 0.040), 402.2 (t = 2.994, p = 0.010), 424.0 (t = 2.644, p = 0.019). Kidney transplant patients with ACR could be distinguished from those without ACR using four individual small molecules with a specificity of 100%. In conclusion, the combination of MALDI-FTMS technology with a clear definition of patient groups can detect urine small molecule associated with ACR.

Evaluation of the relationship between heart type fatty acid binding protein levels and the risk of cardiac damage in patients with obstructive sleep apnea syndrome

The aim of this study was to establish cardiac damage related to nocturnal ischemia using heart type fatty acid binding protein (h-fabp), which reaches detectable levels in plasma after being released from myocytes in case of ischemia in obstructive sleep apnea syndrome (OSAS) patients without coronary artery disease (CAD). Fifty patients diagnosed with OSAS in our sleep laboratory with polysomnographic analysis (PSG), who did not have any previous history of cardiac disease and in whom CAD was ruled out with myocardium perfusion scintigraphy, were included in the study. Control group comprised 19 volunteers without history of cardiac disease and risk factors in whom OSAS was excluded with PSG analysis. Blood samples were drawn from the patients to examine h-fabp, creatine kinase (CK), creatine kinase-MB (CK-MB), aspartate aminotransferase (AST), troponin I levels before and after sleep. No significant difference was found in CK, CK-MB, AST, Troponin I, and h-fabp levels before and after sleep in patient and control groups (p > 0.05). No significant difference was found between groups in terms of CK, CK-MB, AST, and Troponin I levels before and after sleep, while a significant difference was found between them with regard to h-fabp levels before (p = 0.006) and after sleep (p = 0.022). When arithmetical mean of the fabp levels before and after sleep was taken in the patient group, it was found that mean value of h-fabp was associated with the desaturated period in sleep which was under 80% (p = 0.04). H-fabp seems to be a marker that will enable the detection of cardiac injury in the early asymptomatic period in OSAS patients before development of disease that can be detected by imaging methods. Further studies are required to investigate the relation between the value of h-fabp and the development of cardiac dysfunction in the long term.

Cardiac troponin I for accurate evaluation of cardiac status in myopathic patients

BACKGROUND

Brain natriuretic peptide (BNP) and left ventricular ejection fraction (LVEF) are standard indexes for cardiac function. However, they can not reveal myocardial damage directly and they often remain normal even in advanced cardiomyopathy in immobilized patients. Myocardial markers such as MB type of creatine kinase (CK-MB), heart-type fatty acid binding protein (H-FABP) and cardiac troponins are expected to evaluate active myocardial degeneration. However, their availabilities in these patients have not been examined yet.

METHODS

Participants were 129 patients with dystrophinopathies; 100 Duchenne muscular dystrophy (DMD), 25 Becker muscular dystrophy (BMD) and 4 DMD/BMD carriers. Various serological cardiac indexes, including CK-MB, H-FABP, cardiac troponin I (cTnI), BNP and LVEF were measured and statistical analysis was done.

RESULTS

CK-MB and H-FABP was highly associated with creatine kinase (CK). On the contrary, cTnI, BNP and LVEF were independent from CK. In DMD, relatively high cTnI values were observed in patients with motor ability of rowing wheelchair and in their second decade. BNP and LVEF was strongly correlated. However, cTnI was independent from LVEF and only weak correlation could be detected between cTnI and BNP.

CONCLUSION

cTnI had been proven to be expressed in myocardium exclusively. Our results also certified that cTnI can assess cardiac degeneration independently from skeletal muscle degeneration and is practical index even in myopathic patients. Our findings also suggested that cardiac degeneration was preceded to functional impairment in many cases. It indicated that cTnI enable us to detect early stage of cardiac degeneration and initiate intervention at proper stage.

Heart fatty acid binding protein in the diagnosis of myocardial infarction: where do we stand today?

Heart fatty acid binding protein (hFABP) is a novel small cytosolic protein that is abundant in the heart. It is highly cardiac-specific (i.e. expressed primarily in cardiac tissue), but is also expressed at low concentrations in tissues outside the heart. After myocardial ischemic damage, hFABP can be detected in the blood as early as 1-3 h after onset of chest pain, with peak values reached at 6-8 h and plasma levels returning to normal within 24-30 h. hFABP's clinical diagnostic value is very limited in the presence of renal failure and skeletal muscle diseases as it is completely renally eliminated. In these conditions, the diagnosis of acute myocardial infarction (AMI) may be overestimated. The combination of initial hFABP release after symptom onset, rapid kidney clearance from the circulation and high cardiac specificity suggests great potential for clinical use. Serial measurements of hFABP in the first 24 h after onset of symptoms in AMI patients can: (a) identify patients who are susceptible to reperfusion strategies, (b) detect perioperative AMIs, (c) distinguish patients who reperfuse their infarct-related artery from those who do not, as early as 30 min after starting thrombolytic treatment, (d) detect re-infarction if it occurs within 10 h after symptom onset, and (e) permit an accurate estimation of myocardial infarct size providing important prognosis information.

Clinical Evaluation of Point‐of‐Care‐Testing of Heart‐Type Fatty Acid‐Binding Protein (H‐FABP) for the Diagnosis of Acute Myocardial Infarction

The present study was carried out for clinical evaluation of point-of-care-testing (POCT) of heart-type fatty acid-binding protein (H-FABP), Rapicheck H-FABP, for the diagnosis of acute myocardial infarction (AMI), in comparison with conventional cardiac biochemical markers such as myoglobin, creatine kinase isoenzyme MB (CK-MB), and cardiac troponin T. Whole blood samples from patients with confirmed AMI (n = 53), patients with non-AMI cardiac diseases (n = 24), and patients with non-cardiac diseases with chest pain (n = 6) were used. When a test line appeared within 15 min after the addition of 150 microL of whole blood, it was designated to be positive for H-FABP. A control line indicates a proper use of the test. On the other hand, when no test line appeared, it was negative. In the superacute phase of AMI within 3 hours, the diagnostic sensitivity of H-FABP was 93.1%, which was the highest of the four markers compared here. The diagnostic specificity in the phase for H-FABP was 64.3%, while it was 100% with cardiac troponin T. The POCT of H-FABP is thought to be practical for the detection of cardiac damage and effective for the diagnosis of AMI in superacute phase within 3 hours and/or 6 hours.

Urinary protein expression patterns in children with sleep-disordered breathing: Preliminary findings

BACKGROUND

Obstructive sleep apnea (OSA) is the most common form of sleep-disordered breathing, with almost 15 million Americans affected and many more at risk. Current diagnostic approach to OSA requires polysomnography, which is laborious, onerous, and time-consuming. There is ample evidence that inflammatory responses to the perturbations associated with OSA trigger a variety of genes and signaling cascades that ultimately lead to end-organ injury and changes in kidney function and protein expression. The aim of this study was therefore to analyze proteins in human urine and assess whether differential expression of particular proteins is associated with the presence of OSA.

METHODS

Eleven OSA and 11 control children between the ages of three and 14 (males=17; females=5) underwent overnight sleep studies followed by a first-morning urine sample. Proteomic analysis of urine samples yielded a unique map of proteins, of which, five spots were selected for further analysis due to their significant intensity differences between OSA and control groups.

RESULTS

Mass spectrometry followed by peptide mass fingerprinting conclusively identified four of the five spots as gelsolin, perlecan (a heparan sulfate proteoglycan), albumin, and immunoglobulin (P<0.05 and protein scores>67).

CONCLUSIONS

Overall, increased expression of gelsolin and perlecan in the urinary proteome of children with OSA suggests that the episodic hypoxia associated with OSA may lead to changes in protein permeability or alternatively to increased catabolism of these proteins and their excretion in urine.

Unbound Free Fatty Acids and Heart-Type Fatty Acid–Binding Protein: Diagnostic Assays and Clinical Applications

Background: A biomarker that reliably detects myocardial ischemia in the absence of necrosis would be useful for initial identification of unstable angina patients and for differentiating patients with chest pain of an etiology other than coronary ischemia, and could provide clinical utility complementary to that of cardiac troponins, the established markers of necrosis. Unbound free fatty acids (FFAu) and their intracellular binding protein, heart-type fatty acid–binding protein (H-FABP), have been suggested to have clinical utility as indicators of cardiac ischemia and necrosis, respectively.

Methods: We examined results of clinical assessments of FFAu and H-FABP as biomarkers of cardiac ischemia and necrosis. Data published on FFAu and H-FABP over the past 30 years were used as the basis for this review.

Results: Although little clinical work has been done on FFAu since the initial reports, recent studies documented an association between increased serum FFAs and ventricular dysrhythmias and death in patients with acute myocardial infarction (AMI). Recent data suggest that serum FFAu concentrations increase well before markers of cardiac necrosis and are sensitive indicators of ischemia in AMI. H-FABP is abundant in cardiac muscle and is presumed to be involved in myocardial lipid homeostasis. Similar to myoglobin, plasma H-FABP increases within 3 h after AMI and returns to reference values within 12–24 h.

Conclusions: FFAu may have a potential role in identifying patients with cardiac ischemia. H-FABP is useful for detecting cardiac injury in acute coronary syndromes and predicting recurrent cardiac events in acute coronary syndromes and in congestive heart failure patients. Assays are available for both markers that could facilitate further clinical investigations to assess their possible roles as markers of cardiac ischemia and/or necrosis.

Detection of brain injury by fatty acid-binding proteins

The rapid detection of brain injury (neuronal damage in general) is an important parameter in the management of cerebrovascular accidents, especially in hemorrhagic and/or ischemic events. Two types of 15-kDa cytoplasmic fatty acid-binding proteins (FABPs), brain-type FABP and heart-type FABP, have recently been postulated as novel markers for brain injury detection. Here we review the possible roles of these FABPs as rapid diagnostic markers for the detection of brain injury due to cerebrovascular accident, trauma or neurodegenerative diseases. The occurrence of brain- and heart-type FABPs in segments of the human brain is also described. Although only limited amounts of data are available, brain- and heart-type FABPs show higher sensitivities and specificities than protein S100 and neuron specific enolase in the rapid detection of brain injury in stroke, trauma and neurodegenerative diseases.

Relationship between heart-type fatty acid-binding protein levels and the risk of death in patients with serious condition on arrival at the emergency department

OBJECTIVE

Although heart-type fatty acid-binding protein (H-FABP) is a cardiac marker useful for early diagnosis of acute myocardial infarction (AMI), few data are available on its prognostic value. The objective of this study is to clarify the prognostic value of H-FABP in patients with a serious condition.

METHODS AND PATIENTS

We conducted a prospective study of 617 patients who presented to the emergency department with a serious condition. The H-FABP levels on arrival at the emergency department were divided into four groups using their quartiles. The endpoint was death from any causes in-hospital.

RESULTS

H-FABP ranged from 1.2 to 2,300 ng/ml, with a median of 19.9 ng/ml, a 25%-value of 6.7 ng/ml and 75%-value of 54.0 ng/ml. The unadjusted rate of the mortality increased progressively with increasing H-FABP quartile point (11% for quartile-I, 22% for quartile-II, 36% for quartile-III, and 38% for quartile-IV; p<0.001). After adjustment for age, gender, systolic blood pressure and the presence or absence of cardiovascular disease, H-FABP was the independent factor to predict the mortality.

CONCLUSION

H-FABP has proven to be an independent factor for prognosis in patients with a serious condition on arrival at the emergency department.

Performance of a semi-quantitative whole blood test for human heart-type fatty acid-binding protein (H-FABP)

OBJECTIVES

We evaluated the accuracy of visually reading the whole blood Rapicheck H-FABP panel test using the quantitative plasma H-FABP concentration as the reference.

SUBJECTS AND METHODS

Consecutive patients with chest pain (n = 237) who were suspected of having acute myocardial infarction were recruited. The appearance of an evident test line within 5 min was given a grade of +3 (strongly positive), appearance within 15 min +2 (moderately positive) and the appearance of a weak test line within 15 min +1 (weakly positive).

RESULTS AND DISCUSSION

The concordance rates were 91.8% for positive, 70.1% for negative and 80.2% for overall. Plasma H-FABP concentrations were above the cut-off value for 9.2% of negative (0) results. Fifty percent of weakly positive (+1) and 25.0% of moderately positive (+2) results had H-FABP concentrations lower than the cut-off value. All of the strongly positive (+3) were above the cut-off value. These results suggested that the false-positive and false-negative results of Rapicheck H-FABP were caused by over or underestimation in visual reading when the plasma H-FABP concentration was near the cut-off concentration.

CONCLUSIONS

Low accuracy of visual reading of Rapicheck H-FABP was due to poor estimation by manual reading around the cut-off value.

Effects of autotransfusion of mediastinal shed blood on biochemical markers of myocardial damage in coronary surgery

BACKGROUND

Previous studies have shown conflicting results regarding the effect of autotransfusion of mediastinal shed blood after coronary artery bypass grafting (CABG) on the serum levels of myocardial band (MB) isoenzymes of creatine kinase (CK-MB) and cardiac troponins. The effect of autotransfusion on serum levels of human heart fatty acid binding protein (H-FABP), another marker of myocardial necrosis, has not been studied. The aim of the present study was to investigate the effects of autotransfusion of mediastinal shed blood on the serum levels of CK-MB, cardiac troponin T (cTnT), and H-FABP after uncomplicated primary CABG.

METHODS

Fifty patients were randomized to post-operative autotransfusion of mediastinal shed blood or no autotransfusion. Blood samples for the analysis of the biochemical markers of myocardial damage were drawn pre-operatively and 1, 4, 12, 24, 48, and 72 h after the termination of cardiopulmonary bypass. Samples from the mediastinal shed blood were collected after 1 and 4 h.

RESULTS

The levels of the biochemical markers of myocardial injury were all markedly elevated in mediastinal shed blood. Autotransfusion did not significantly affect the serum levels of cTnT or H-FABP. However, during the early post-operative hours, there was a trend towards a higher level of cTnT and H-FABP in the autotransfusion group. During the first 24 h after surgery, the autotransfusion group had a significantly higher serum level of CK-MB.

CONCLUSION

Post-operative autotransfusion of mediastinal shed blood may contribute to elevated serum levels of biochemical markers of myocardial injury.

Prognostic value of serum concentration of heart-type fatty acid-binding protein relative to cardiac troponin T on admission in the early hours of acute coronary syndrome

BACKGROUND

Heart-type fatty acid-binding protein (H-FABP) is proposed as an early biomarker for acute myocardial infarction (AMI), but its prognostic value is unclear in acute coronary syndrome (ACS). We evaluated the prognostic value of the H-FABP concentration relative to cardiac troponin T (cTnT) in the early hours of ACS.

METHODS

Serum concentrations of H-FABP and cTnT were measured on admission in 328 consecutive patients hospitalized for ACS within 6 h after the onset of chest pain [AMI, 241 (73.5%) patients; ST-segment elevation myocardial infarction, 154 (47.0%) patients; and emergent coronary angiography within 24 h after admission, 287 (87.5%) patients]. Cardiac events, which were defined as cardiac death or subsequent nonfatal AMI, were monitored for 6 months after admission.

RESULTS

During the 6-month follow-up period, there were 25 cardiac events, including 15 cardiac deaths and 10 subsequent nonfatal AMIs. Stepwise multivariate analyses including clinical, electrocardiographic, and biochemical variables revealed that increased H-FABP (above the median of 9.8 microg/L), but not increased cTnT (above the median of 0.02 microg/L), was independently associated with cardiac events in all patients [relative risk (RR) = 8.96; P = 0.0004], the subgroup of patients with ST-segment elevation myocardial infarction (RR = 11.3; P = 0.02), and the subgroup of patients with unstable angina and non-ST-segment elevation myocardial infarction (RR = 8.31; P = 0.007). The area under the ROC curve was higher for H-FABP than for cTnT (0.711 vs 0.578; P = 0.08), suggesting that H-FABP concentrations have a greater predictive capacity for cardiac events than cTnT.

CONCLUSION

Serum H-FABP is a potential independent predictor of cardiac events within 6 months of patient admission and may provide prognostic information superior to cTnT in the early hours of ACS.

Rapid analysis of fatty acid-binding proteins with immunosensors and immunotests for early monitoring of tissue injury

Fatty acid-binding protein (FABP) holds promise for early detection of tissue injury. This small protein (15kD) appears earlier in the blood than large proteins after cell damage. Combined its characteristics of high concentration tissue contents and low normal plasma values provide the possibility of a rapid rise above the respective reference values, and thus an early indication of the appearance of tissue injury. A general review was presented on the current status of different types of FABP for the detection of tissue injury in patients with myocardial injury, brain injury and also in athletes or horses with skeletal muscle injury. To take full advantage of the characteristics of the early marker FABP, rapid analysis is a crucial parameter. In this review, an overview of the development of immunoassay for the quantification of FABP in buffer, plasma or whole blood was outlined. The characteristics of different FABP immunosensors and immunotests were described. The feasibility of these immunoassays to be used in routine clinical practice and in emergency case was also discussed. Nowadays, the improved automated immunoassays (e.g. a microparticle-enhanced turbidimetric immunoassay), less time-consuming bedside immunosensors and immunotests (e.g. a one-step FABP lateral flow immunotest), are the main advance technology in point-of-care testing. With these point-of-care tests, the application of FABP as an early tissue injury marker has a great potential for many clinical purposes.

Fatty acid-binding proteins as plasma markers of tissue injury

BACKGROUND

One of the novel and promising plasma markers for detection of tissue injury is the family of 15 kDa cytoplasmic fatty acid-binding proteins of which various tissue-specific types occur.

AIMS AND OBJECTIVES

The present status of heart-type fatty acid-binding protein (H-FABP) as a diagnostic and prognostic marker for acute and chronic cardiac injury, as well as the preliminary diagnostic use of other types of FABP for detecting injury in other organs, is reviewed.

METHODS

This review is based on an overview of the literature on clinical diagnostics of various forms of organ injury, and uses additional literature on physiological aspects relevant for the interpretation of plasma marker concentrations.

RESULTS

H-FABP not only proves to be an excellent early marker for cardiac injury in acute coronary syndromes, but also allows detection of minor myocardial injury in heart failure and unstable angina. Preliminary results indicate that sensitivity, rule-out power and prognostic value of H-FABP in cardiac injury surpass the performance of the standard early marker myoglobin. The liver only contains liver-type FABP (L-FABP), but co-expression of H-FABP and L-FABP occurs in the kidney. Similarly, intestinal-type FABP (I-FABP) and L-FABP are found in intestines, and brain-type FABP (B-FABP) and H-FABP occur in the brain. Preliminary but promising applications of these proteins have been demonstrated for liver rejection, viability selection of kidneys from non-heart-beating donors (NHBD), inflammatory and ischemic bowel disease, traumatic brain injury and in the prevention of muscle injury in trained athletes.

CONCLUSIONS

Further study of the diagnostic and prognostic use of various FABP types is warranted, but their clinical application will require further commercialization of automated and rapid assays.

The dependence of myocardial damage on age and ischemic time in pediatric cardiac surgery

OBJECTIVE

Heart fatty acid-binding protein is a rapid indicator for assessment of myocardial damage in cardiac surgery. The purpose of this study was to investigate the effects of age and ischemic time on the biochemical evidence and clinical outcomes of myocardial damage in pediatric cardiac surgery.

METHODS

A prospective observational cohort study conducted over 2.5 years was performed in 98 consecutive patients (51 infants and 47 children) undergoing cardiac surgery for ventricular septal defects. Serial measurements of serum levels of heart fatty acid-binding protein and the respective areas under the curve were obtained, with particular reference to age and aortic crossclamp time. Assessment of clinical outcomes included inotropic support, ventilatory support, and intensive care unit stay.

RESULTS

There was a linear dependence of the logarithm of age and the logarithm of heart fatty acid-binding protein release(r = 0.737, P < .0001). This logarithm-logarithm plot showed a power function of age for heart fatty acid-binding protein release. The exponent and amplitude parameter of the power function was the aortic crossclamp time. Compared with children, infants had significantly more myocardial damage and worse clinical outcomes, and these factors were related to the aortic crossclamp time.

CONCLUSIONS

The younger the age of patients, the more vulnerable are their myocardia to injury caused by ischemia during definitive repair of congenital heart disease. Therefore, perioperative management for pediatric patients after cardiac surgery should be performed, taking into consideration the dependence of the myocardial damage on age and ischemic time.

Combination of Heart-Type Fatty Acid Binding Protein and Brain Natriuretic Peptide Can Reliably Risk Stratify Patients Hospitalized for Chronic Heart Failure

BACKGROUND

The aim of the present study was to prospectively study whether a combination of markers for myocardial cell injury and left ventricular overload at admission can reliably risk stratify patients hospitalized for chronic heart failure (CHF).

METHODS AND RESULTS

Serum concentrations of heart-type fatty acid binding protein (H-FABP) and plasma concentrations of brain natriuretic peptide (BNP) were measured at admission in 186 consecutive patients hospitalized for CHF. During a mean follow-up period of 534+/-350 days, there were 44 cardiac events, including 16 cardiac deaths and 28 readmissions for worsening heart failure. Normal upper limits for H-FABP and BNP values were determined from the receiver operating characteristic curves (4.3 ng/ml for H-FABP and 200 pg/ml for BNP). A stepwise Cox regression analysis demonstrated that high H-FABP (hazard ratio 5.416, p = 0.0002) and high BNP (hazard ratio 2.411, p = 0.0463) were independent predictors of cardiac events. High concentrations of both H-FABP and BNP at admission were associated with the highest incidence of cardiac mortality and cardiac events. Kaplan-Meier analysis also showed that the combination of H-FABP and BNP concentrations could reliably stratify patients for cardiac events.

CONCLUSION

Combined measurement of H-FABP and BNP concentrations at admission may be a highly reliable evaluation for risk stratifying patients hospitalized for CHF.

Proteomic Identification of a Large Complement of Rat Urinary Proteins

The characterization of urinary proteins is an important tool to identify disease-related biomarkers and to better understand renal physiology. Expression of urinary proteins has been previously studied by Western blotting and other immunological methods. The scope of such studies, however, is limited to previously identified proteins for which specific antibodies are existed. We used proteomic analysis to identify proteins and to construct a proteome map for Sprague-Dawley (SD) rat urine isolated by ultracentrifugation. Urinary proteins were separated by two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) and visualized by silver staining. Proteins were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), followed by peptide mass fingerprinting using the NCBI protein database. A total of 350 protein spots were visualized. From 250 excised spots, 111 protein components were identified including transporters, transport regulators, chaperones, enzymes, signaling proteins, cytoskeletal proteins, pheromone-binding proteins, receptors, and novel gene products. The presence of a number of these identified proteins was unexpected and had not previously been identified in the urine. 2-D Western blot analyses for randomly selected proteins (ezrin, HSP70, beta- and gamma-actin, Rho-GDI, and l-myc) clearly confirmed the proteomic identification. Several potential posttranslational modifications were predicted by bioinformatic analyses. These data indicate that a large complement of expected and unexpected urinary proteins can be simultaneously studied by proteomic analysis. This approach may lead to better understanding of renal physiology and pathophysiology, and to biomarker discovery.

Proteomic patterns established with capillary electrophoresis and mass spectrometry for diagnostic purposes

BACKGROUND

Proteomics applied in large scale may provide a useful diagnostic tool.

METHODS

We developed an online combination of capillary electrophoresis with mass spectrometry, allowing fast and sensitive evaluation of polypeptides found in body fluids. Utilizing this technology, polypeptide patterns from urine are established within 45 minutes. About 900 to 2500 polypeptides as well as their concentrations are detected in individual urine samples without the need for specific reagents such as antibodies. To test this method for clinical application, we examined spot urine samples from 57 healthy individuals, 16 patients with minimal change disease (MCD), 18 patients with membranous glomerulonephritis (MGN), and 10 patients with focal segmental glomerulosclerosis (FSGS).

RESULTS

One-hundred seventy-three polypeptides were present in more than 90% of the urine samples obtained from healthy individuals, while 690 polypeptides were present with more than 50% probability. These data permitted the establishment of a "normal" polypeptide pattern in healthy individuals. Polypeptides found in the urine of patients differed significantly from the normal controls. These differences allowed the distinction of specific protein spectra in patients with different primary renal diseases. Abnormal pattern of proteins were found even in urine from patients in clinical remission.

CONCLUSION

The data indicate that capillary electrophoresis with mass spectrometry coupling provides a promising tool that permits fast and accurate identification and differentiation of protein patterns in body fluids of healthy and diseased individuals, thus enabling diagnosis based on these patterns.

Evaluation of heart fatty acid–binding protein as a rapid indicator for assessment of myocardial damage in pediatric cardiac surgery

OBJECTIVES

Perioperative myocardial damage is a major determinant of postoperative cardiac dysfunction for congenital heart disease. Heart fatty acid-binding protein is reported to be a rapid marker of perioperative myocardial damage that peaks earlier than creatine kinase isoenzyme MB or cardiac troponin T in adults. The objective of this study was to assess the suitability of using serum concentrations of heart fatty acid-binding protein for evaluation of perioperative myocardial damage in pediatric cardiac surgery.

METHODS

After institutional review board approval and informed consent, 100 children undergoing open procedures for congenital heart disease were prospectively enrolled in the study. Mean age at operation was 4.9 +/- 0.4 years. Serum concentrations of heart fatty acid-binding protein, creatine kinase isoenzyme MB, and cardiac troponin T were measured serially before operation and at 0, 1, 2, 3, and 6 hours after aortic declamping. Relationships between serum peak level of heart fatty acid-binding protein and intraoperative and postoperative clinical variables were evaluated.

RESULTS

Serum heart fatty acid-binding protein reached its peak level at 1 hour after declamping in 95 patients (95%), which was significantly earlier (P <.01) than serum creatine kinase isoenzyme MB or cardiac troponin T. In addition, serum heart fatty acid-binding protein level immediately after declamping correlated strongly with serum peak heart fatty acid-binding protein level (r = 0.91, P <.01). The serum peak level of heart fatty acid-binding protein correlated with those of creatine kinase isoenzyme MB (r = 0.77, P <.01) and cardiac troponin T (r = 0.80, P <.01). In the forward stepwise multiple regression analysis, age (P <.0001), aortic crossclamp time (P <.0001), the presence of a ventriculotomy (P <.001), and the lowest hematocrit level during cardiopulmonary bypass (P <.05) were significant intraoperative variables that influenced the release of heart fatty acid-binding protein. There were significant relationships between serum peak heart fatty acid-binding protein level and postoperative inotropic support, duration of intubation, and intensive care unit stay (P <.01 for each).

CONCLUSIONS

Heart fatty acid-binding protein is a rapid marker for assessment of myocardial damage and clinical outcome in pediatric cardiac surgery. In particular, serum heart fatty acid-binding protein level immediately after aortic declamping may be a potentially useful prognostic indicator of myocardial damage as well as clinical outcome in pediatric cardiac surgery.

Do we need additional markers of myocyte necrosis: the potential value of heart fatty-acid-binding protein

Heart fatty-acid-binding protein (FABP) is a small cytosolic protein that is abundant in the heart and has low concentrations in the blood and in tissues outside the heart. It appears in the blood as early as 1.5 h after onset of symptoms of infarction, peaks around 6 h and returns to baseline values in 24 h. These features of H-FABP make it an excellent potential candidate for the detection of acute myocardial infarction (AMI). We review the strengths and weaknesses of H-FABP as a clinically applicable marker of myocyte necrosis in the context of acute coronary syndromes.

Pericardial fluid level of heart-type cytoplasmic fatty acid-binding protein (H-FABP) is an indicator of severe myocardial ischemia

BACKGROUND

Heart-type cytoplasmic fatty acid-binding protein (H-FABP) has been reported as a sensitive and specific marker for the early diagnosis of acute myocardial infarction. Our hypothesis was that serum or pericardial fluid levels of H-FABP can reflect not only myocardial infarction but also myocardial ischemia.

METHODS

A total of 34 patients with unstable angina, who had anginal symptoms and/or ST-changes in ECG monitoring within 24 h before operation, were classified into group A (n=17), and those without these symptoms and changes into group B (n=17). Blood and pericardial fluid samples were obtained immediately after median sternotomy, and serum and pericardial fluid levels of creatine kinase-MB, cardiac troponin-T, and H-FABP were measured.

RESULTS

Serum H-FABP levels were slightly elevated compared with their normal values in both groups. While they showed no difference between groups A and B (group A vs. B: 8.5+/-1.0 vs. 7.1+/-0.7 ng/ml, P=0.25), pericardial fluid levels of H-FABP were significantly higher in group A than in group B (16.3+/-2.0 vs. 9.6+/-1.0 ng/ml, P=0.0046). H-FABP showed a weak correlation between its serum levels and pericardial fluid levels (r=0.40).

CONCLUSIONS

Pericardial fluid levels of H-FABP reflect myocardial ischemia occurring within 24 h of their measurements. H-FABP may be secreted into the interstitial space by increased permeability of the myocardial cell membrane associated with severe myocardial ischemia. Thus, pericardial fluid reflects pathophysiological conditions of cardiomyocytes more sensitively than circulating blood.

Ongoing Myocardial Damage in Chronic Heart Failure is Related to Activated Tumor Necrosis Factor and Fas/Fas Ligand System

BACKGROUND

Elevated concentrations of cardiac troponin T and heart-type fatty acid-binding protein (H-FABP) identify patients with chronic heart failure (CHF) and ongoing myocardial damage (OMD) who are at increased risk for future cardiac events. Cardiomyocyte necrosis and/or apoptosis via activated tumor necrosis factor (TNF) and the Fas/Fas ligand (FasL) system may be related to the development of OMD.

METHODS AND RESULTS

The serum concentrations of H-FABP, a sensitive marker of membrane damage of cardiomyocytes, soluble Fas (sFas) and TNF-alpha were measured in 38 patients with CHF. The concentrations of H-FABP, TNF-alpha and s-Fas in patients with New York Heart Association (NYHA) III + IV were all significantly higher than in those patients in NYHA II (H-FABP; III + IV 9.3+/-5.9 vs II 5.1+/-1.8 ng/ml, p=0.003, TNF-alpha; III + IV 10.5+/-3.8 vs II 8.0+/-2.7 pg/ml, p=0.02, sFas; III + IV 3.36+/-1.37 vs II 2.58 +/-0.84 ng/ml, p=0.03). Increased concentrations of H-FABP significantly correlated with the concentrations of TNF- alpha (r=0.57, p=0.0001) and sFas (r=0.69, p<0.0001), independent of renal function.

CONCLUSION

OMD detected by H-FABP, a marker of membrane damage, is related to activated TNF and the Fas/FasL system, which suggests a pathophysiological role of cardiomyocyte necrosis and/or apoptosis in patients with worsening heart failure.

Office Cardiologists Cooperative Study on Whole Blood Rapid Panel Tests in Patients With Suspicious Acute Myocardial Infarction

BACKGROUND

The whole blood rapid troponin T test, used to determine the early diagnosis of acute myocardial infarction (AMI), is effective only for 3-4 h after onset.

METHODS AND RESULTS

The present office cardiologists cooperative study compared the diagnostic efficacy of a newly developed whole blood rapid panel test for heart-type fatty acid-binding protein (H-FABP) with that of the rapid troponin T test in 129 consecutive patients with suspicious AMI according to certain time-frames from onset to presentation. Thirty-one patients (24.0%) had a final diagnosis of AMI. The respective sensitivities of the rapid H-FABP and troponin T tests were 100% vs 50% (p<0.05) for patients presenting within 3 h of onset; 75% vs 0% for those between 3 and 6 h; 100% vs 60% for those between 6 and 12 h; and 100% vs 100% for those presenting later than 12 h. The respective specificities were 63% vs 96.3% (p<0.05); 93.8% vs 93.8%; 72.7% vs 100%; and 75.0% vs 87.5%. Negative predictive value was 100% vs 86.7%; 93.8% vs 78.9%; 100% vs 84.6%; and 100% vs 100%, respectively. Patients with non-AMI myocardial damage associated with unstable angina or severe heart failure showed positive H-FABP test results and blunted the specificity.

CONCLUSIONS

When using the novel rapid H-FABP test, cardiac emergency triage to exclude non-AMI patients should be effectively organized within 3 h of onset.

Utility of Serum Ratio of Heart-Type Fatty Acid-Binding Protein to Myoglobin for Cardiac Damage Regardless of Renal Dysfunction

BACKGROUND

The serum ratio of heart-type fatty acid-binding protein to myoglobin (F/M) has been shown to be a new marker for cardiac damage and volume overload in hemodialysis patients. We evaluated the utility of F/M in hemodialysis patients compared to control subjects.

METHODS AND RESULTS

Twenty-one hemodialysis patients and 17 control subjects with normal renal function were investigated. Using a cutoff point of mean + 2SD of the F/M in the controls (value: 0.147), the hemodialysis patients were divided into 2 groups. The concentrations of atrial natriuretic peptide (ANP) and brain natriuretic peptide after hemodialysis in the high F/M group were higher than those in the low F/M group. The mean level of ANP in the low F/M group was almost the upper limit of normal range. The values of left ventricular end-diastolic dimension and left ventricular mass index in the high F/M group were higher than those in the low F/M group, and the mean levels of those in the low F/M group were almost the same as those in the controls.

CONCLUSIONS

The F/M can be evaluated by the absolute value regardless of renal dysfunction, and the value of 0.147 might be useful for determining the cutoff level of cardiac involvement.

Development of a displacement immunoassay for human heart-type fatty acid-binding protein in plasma: the basic conditions

To risk-stratify patients with chest pain who are admitted to emergency rooms and for whom initial evaluation is not conclusive, the use of cardiac markers has become a standard procedure. A recently introduced early plasma marker for acute myocardial infarction (AMI) is the 14.5-kDa cytoplasmic heart-type fatty acid-binding protein (FABP). To fully exploit its early release from injured myocardium, a rapid method for repeated measurements or continuous monitoring of FABP in plasma is desirable. Such an on-line method could be an immunosensor based on displacement. The aim of the present study was to further investigate the principles underlying the displacement assay of FABP, both in buffer and in plasma. Batches of sepharose-bound FABP were loaded with an antibody-horseradish peroxidase (HRP) conjugate (anti-FABP). Continuous measurement of FABP was mimicked by repeated addition of FABP containing solutions followed by several washing steps. In the presence of free FABP the antibody-HRP complex dissociated and was subsequently quantified. Significant displacement in the presence of free FABP was observed in both buffer and human plasma. Anti-FABP could be intermittently displaced in the same batch, for at least 9 h, and the displacement was concentration-dependent. These results show the feasibility of a sensor based on the displacement principle to be used for the diagnosis of AMI in emergency medicine.

Capillary electrophoresis coupled to mass spectrometry to establish polypeptide patterns in dialysis fluids

Combination of capillary electrophoresis with mass spectrometry (CE-MS) allows generation of polypeptide patterns of body fluids. In a single CE-MS (45 min) run more than 600 polypeptides were analyzed in hemodialysis fluids obtained with different membranes (high-flux/low-flux). Larger polypeptides (M(r) > 10 000) were almost exclusively present in high-flux dialysates only, while in low-flux dialysates additional small polypeptides were detected. Comparison to the normal urine pattern yielded a surprisingly low consensus: a number of polypeptides present in urine were missing. We established a fast and sensitive technique, easily applicable to the monitoring of different modalities of dialyzers.

Human heart-type fatty acid-binding protein as an early diagnostic and prognostic marker in acute coronary syndrome

Although heart-type fatty acid-binding protein (H-FABP) can be a marker of sarcolemmal injury due to acute myocardial ischemia, the diagnostic or prognostic value is not established in patients with acute chest pain. This multicenter prospective study aimed to determine the diagnostic and prognostic values of H-FABP in 133 patients presenting to an emergency room with suspected acute coronary syndrome (ACS) by comparing with those of conventional biomarkers. H-FABP and myoglobin had greater positive results than did creatine kinase-MB or troponin T. Receiver operating characteristics analysis revealed that H-FABP was the most reliable for detection of ACS and that H-FABP had the greatest sensitivities for identification of patients requiring emergency hospitalization, coronary angiography, and interventional therapy within 7 days among the biomarkers. Thus, H-FABP can be an early diagnostic and prognostic biochemical marker, particularly within the first 6 h from the onset of chest symptoms, in patients with chest pain at an emergency department.

Use of a whole blood rapid panel test for heart-type fatty acid-binding protein in patients with acute chest pain: comparison with rapid troponin T and myoglobin tests

PURPOSE

We sought to determine the clinical utility of a newly developed qualitative test to measure heart-type fatty acid-binding protein levels in blood for the early identification of myocardial infarction.

METHODS

We measured heart-type fatty acid-binding protein levels in 371 consecutive patients with acute chest pain and suspected myocardial infarction, and compared the performance of this test with those of troponin T and myoglobin tests. Levels of heart-type fatty acid-binding protein >or=6.2 ng/mL were considered as positive results.

RESULTS

A final diagnosis of acute myocardial infarction was made in 181 patients (49%). Of the 68 patients who presented within 2 hours of the onset of symptoms, 37 (54%) had a final diagnosis of myocardial infarction. The sensitivity of the rapid heart-type fatty acid-binding protein test was 89% (33/37), significantly higher than for troponin T (22% [8/37]; P<0.001) and myoglobin (38% [14/37]; P<0.001). However, the specificity of troponin T (94% [29/31]) was significantly better than for heart-type fatty acid-binding protein (52% [16/31]; P= 0.002) within 2 hours. The area under the receiver operating characteristic curve for heart-type fatty acid-binding protein levels was greater than that for myoglobin (0.72 vs. 0.61, P = 0.01) among patients who presented within 2 hours.

CONCLUSION

A novel whole blood rapid heart-type fatty acid-binding protein test can be useful in the early evaluation of patients who present with acute chest pain.

Development of a quantitative lateral-flow assay for rapid detection of fatty acid-binding protein

Using human heart-type fatty acid-binding protein (H-FABP) as an early cardiac marker to confirm or exclude a diagnosis of acute myocardial infarction (AMI) soon after admission requires a rapid assay system. Due to the requirement of skillful technicians and complicated assay procedures, most immunochemical assays for H-FABP are of limited use for routine clinical practice. In the present study, we describe a rapid lateral-flow assay for detection of H-FABP. Fifty-one human samples were evaluated using a conventional ELISA and a newly developed lateral-flow assay. A good agreement between the two methods was found according to Bland and Altman plot. The correlation found was y=0.9685 x -0.6270 (r(2)=0.9585). The detector antibody labeled with colloidal gold was mixed with those without label to extend the linear range of the calibration curve up to 125 microg/l H-FABP with r(2)=0.9832. The detection limit of the assay was 2.8 microg/l. The test-strips can be stored either at 4 degrees C and room temperature for up to 1 year without significant loss of activity. Finally, a one-step FABP test so-called CardioDetect(R), which was derived from the serum lateral-flow assay has been designed for qualitative determination of H-FABP in whole blood samples. It requires no sample pretreatment and gives results within 15 min. Thirty-eight patients presenting with chest pain and suspected AMI were studied. Using an upper reference level of 7 microg/l, the specificity of the rapid test was 94%. Both sensitivity and negative predictive value (NPV) were 100%, implying that 100% of non-AMI patients could be excluded with no false-negative results. With this rapid and sensitive immunotest, H-FABP could soon be introduced into clinical practice.

Serum ratio of heart-type fatty acid-binding protein to myoglobin. A novel marker of cardiac damage and volume overload in hemodialysis patients

BACKGROUND

The concentration of heart-type fatty acid-binding protein (hFABP), a promising novel marker for detection of acute or persistent myocardial damage, is significantly influenced by renal clearance and thus has limitations to its usefulness in patients with renal dysfunction. We evaluated whether the serum ratio of hFABP to myoglobin (F/M) might be a useful marker for assessing cardiac damage in hemodialysis patients.

METHODS

Serum hFABP and myoglobin were measured, and the value of F/M was calculated in 21 hemodialysis patients. Cardiac markers (cardiac troponin T [cTnT], atrial natriuretic peptide [ANP], and brain natriuretic peptide [BNP]) and echocardiographic indices (left ventricular end-diastolic dimension [LVDd], left ventricular mass index [LVMI], and inferior vena cava [IVC] dimension) were examined and compared with hFABP, myoglobin, and F/M ratios.

RESULTS

Serum hFABP and myoglobin levels were significantly elevated in hemodialysis patients and reduced by 30-40% during hemodialysis. The value of F/M after hemodialysis, but not the concentration of hFABP or myoglobin, had significant linear correlations with ANP, BNP, cTnT, LVDd, LVMI, and IVC.

CONCLUSION

The value of F/M after hemodialysis, but not the concentration of hFABP itself, might be a newly useful marker for estimation of cardiac damage and volume overload in hemodialysis patients.

Use of cytosolic and myofibril markers in the detection of ongoing myocardial damage in patients with chronic heart failure

PURPOSE

Measurement of serum levels of cytosolic and myofibril components of cardiac tissue could indicate ongoing myocardial damage in patients with chronic heart failure.

METHODS

We correlated serum levels of a cytosolic marker (heart-type fatty acid-binding protein) and a myofibril marker (troponin T) with the severity of symptoms (based on the New York Heart Association [NYHA] class), neurohumoral derangement, and subsequent cardiac events in 56 patients with chronic heart failure.

RESULTS

Mean (+/- SD) levels of heart-type fatty acid-binding protein were greater in patients with NYHA class III or IV heart failure (9.9 +/- 5.2 ng/mL) than in those with NYHA class II (4.9 +/- 1.9 ng/mL, P <0.0001). Detection of troponin T (> or =0.02 ng/mL) was also more common in patients with worse heart failure (81% [13/16] in class III or IV vs. 43% [17/40] in class II, P = 0.02). Significant correlations were found between heart-type fatty acid-binding protein levels and plasma levels of A-type natriuretic peptide (r = 0.45, P = 0.0004), B-type natriuretic peptide (r = 0.66, P <0.0001), and norepinephrine (r = 0.36, P = 0.006). Male sex (hazard ratio [HR] = 5.0; 95% confidence interval [CI]: 1.3 to 19), detectable troponin T levels (HR = 7.0; 95% CI: 1.1 to 44), heart-type fatty acid-binding protein (HR = 2.6 per 3.9-ng/mL increase; 95% CI: 1.1 to 6.5), and left ventricular ejection fraction (HR = 3.6 per 15% decrease; 95% CI: 1.2 to 11) were independently associated with subsequent cardiac events (8 deaths or 10 readmissions because of worsening heart failure).

CONCLUSION

Heart-type fatty acid-binding protein and troponin T are markers of ongoing myocardial damage, and are associated with subsequent cardiac events in patients with chronic heart failure.