One-step enzyme-linked immunosorbent assay (ELISA) for plasma fatty acid-binding protein

Life expectancy in cancer patients with pulmonary thromboembolism: From clinical prognostic biomarkers and paraclinical investigations to therapeutic approaches (Review)

Pulmonary embolisms (PEs) are obstructions of the pulmonary arteries by thrombi, which are emboli and they most frequently originate from the deep venous system of the inferior limbs. Emboli can also come from the inferior vena cava, abdominal and pelvic veins, or the upper body venous system from the right atrium or ventricle of the heart. Thrombi can form in situ inside pulmonary arteries as well. A cancer patient is at a higher risk for thromboembolic phenomena given both the oncological pathological context and also due to the associated medical or surgical treatment they receive. PE is a high-risk medical emergency that is associated with an increased risk of early mortality, with sudden death occurring in 25% of patients. The long-term presence of this condition can result in thromboembolic pulmonary hypertension. The risk of mortality, both in the acute and long-term, is dependent on the severity of the acute form, the recurrence of the embolism and the associated conditions. The majority of deaths associated with PE can be prevented by early diagnosis. The aim of the present review was to describe the various biological and cellular parameters, together with known paraclinical investigations, to assist in the rapid diagnosis of PE. Mortality in patients with PE and neoplastic conditions may be reduced by initiating anticoagulant treatment as soon as possible. PE may be the first manifestation of an underlying silent malignancy or may represent a complication of an already diagnosed malignancy. Exclusion or confirmation of the diagnosis is of utmost importance to avoid unnecessary anticoagulant treatment associated with a high risk of bleeding or to start immediate anticoagulant treatment if required.

An integrated microfluidic electrochemiluminescence device for point-of-care testing of acute myocardial infarction

Heart-type fatty acid binding protein (H-FABP) is an early biomarker for acute myocardial infarction. The concentration of H-FABP in circulation sharply increases during myocardial injury. Therefore, fast and accurate detection of H-FABP is of vital significance. In this study, we developed an electrochemiluminescence device integrated with microfluidic chip (designed as m-ECL device) for on-site detection of H-FABP. The m-ECL device is consisted of a microfluidic chip that enable easy liquid handling as well as an integrated electronic system for voltage supply and photon detection. A sandwich-type ECL immunoassay strategy was employed for H-FABP detection by using Ru (bpy)₃²⁺ loaded mesoporous silica nanoparticles as ECL probes. This device can directly detect H-FABP in human serum without any pre-treatment, with a wide linear range of 1-100 ng/mL and a low limit of detection of 0.72 ng/mL. The clinical usability of this device was evaluated using clinical serum samples from patients. The results obtained from m-ECL device are well matched with those obtained from ELISA assays. We believe this m-ECL device has extensive application prospects for point-of-care testing of acute myocardial infarction.

Biomarker Development in Cardiology: Reviewing the Past to Inform the Future

Cardiac biomarkers have become pivotal to the clinical practice of cardiology, but there remains much to discover that could benefit cardiology patients. We review the discovery of key protein biomarkers in the fields of acute coronary syndrome, heart failure, and atherosclerosis, giving an overview of the populations they were studied in and the statistics that were used to validate them. We review statistical approaches that are currently in use to assess new biomarkers and overview a framework for biomarker discovery and evaluation that could be incorporated into clinical trials to evaluate cardiovascular outcomes in the future.

Ratiometric Fluorescent Lateral Flow Immunoassay for Point-of-Care Testing of Acute Myocardial Infarction

We report the development of a highly sensitive ratiometric fluorescent lateral flow immunoassay (RFLFIA) strip for rapid and accurate detection of acute myocardial infarction biomarker, namely heart-type fatty acid binding protein (H-FABP). The RFLFIA strip works in terms of ratiometric change of fluorescence signal, arising from blending of fluorescence emitted by two composite nanostructures conjugated to capture and probe antibodies and inner filter effect of gold nanoparticles. In conjunction with using custom smartphone-based analytical device and tonality analysis, quantitative detection of H-FABP was achieved with a low limit of detection at 0.21 ng mL^-1 . The RFLFIA strip can generate a visually distinguishable green-to-red color change around the threshold concentration of H-FABP (6.2 ng mL^-1 ), thus allowing the semi-quantitative diagnosis by the naked eye.

Hosseini I, Raeissi K, Karimzadeh F, Jalali M, Kharaziha M, Sheibani S, Shariati L, Presley JF, Vali H, Mahshid S. Gold Nano/Micro-Islands Overcome the Molecularly Imprinted Polymer Limitations to Achieve Ultrasensitive Protein Detection

Here, we report on an electrochemical biosensor based on core-shell structure of gold nano/micro-islands (NMIs) and electropolymerized imprinted ortho-phenylenediamine (o-PD) for detection of heart-fatty acid binding protein (H-FABP). The shape and distribution of NMIs (the core) were tuned by controlled electrodeposition of gold on a thin layer of electrochemically reduced graphene oxide (ERGO). NMIs feature a large active surface area to achieve a low detection limit (2.29 fg mL^-1, a sensitivity of 1.34 × 10¹³ μA mM^-1) and a wide linear range of detection (1 fg mL^-1 to 100 ng mL^-1) in PBS. Facile template H-FABP removal from the layer (the shell) in less than 1 min, high specificity against interference from myoglobin and troponin T, great stability at ambient temperature, and rapidity in detection of H-FABP (approximately 30 s) are other advantages of this biomimetic biosensor. The electrochemical measurements in human serum, human plasma, and bovine serum showed acceptable recovery (between 91.1 ± 1.7 and 112.9 ± 2.1%) in comparison with the ELISA method. Moreover, the performance of the biosensor in clinical serum showed lower detection time and limit of detection against lateral flow assay (LFA) rapid test kits, as a reference method. Ultimately, the proposed biosensor based on the core-shell structure of gold NMIs and MIP opens interesting avenues in the detection of proteins with low cost, high sensitivity and significantstability for clinical applications.

Thermal Detection of Cardiac Biomarkers Heart-Fatty Acid Binding Protein and ST2 Using a Molecularly Imprinted Nanoparticle-Based Multiplex Sensor Platform

This manuscript describes the production of molecularly imprinted polymer nanoparticles (nanoMIPs) for the cardiac biomarkers heart-fatty acid binding protein (H-FABP) and ST2 by solid-phase synthesis, and their use as synthetic antibodies in a multiplexed sensing platform. Analysis by surface plasmon resonance (SPR) shows that the affinity of the nanoMIPs is similar to that of commercially available antibodies. The particles are coated onto the surface of thermocouples and inserted into 3D-printed flow cells of different multiplexed designs. We demonstrate that it is possible to selectively detect both cardiac biomarkers within the physiologically relevant range. Furthermore, the developed sensor platform is the first example of a multiplex format of this thermal analysis technique which enables simultaneous measurements of two different compounds with minimal cross selectivity. The format where three thermocouples are positioned in parallel exhibits the highest sensitivity, which is explained by modeling the heat flow distribution within the flow cell. This design is used in further experiments and proof-of-application of the sensor platform is provided by measuring spiked fetal bovine serum samples. Because of the high selectivity, short measurement time, and low cost of this array format, it provides an interesting alternative to traditional immunoassays. The use of nanoMIPs enables a multimarker strategy, which has the potential to contribute to sustainable healthcare by improving the reliability of cardiac biomarker testing.

Development of a Quantitative Detection Card for Heart-type Fatty Acid-binding Protein based on Background Fluorescence Quenching Immune Chromatography

Background

To establish a fast and simple quantitative method for detection of heart-type fatty acid-binding protein (H-FABP) in serum based on a background fluorescence quenching immunochromatographic assay.

Methods

A detection card based on the double-antibody sandwich double-antibody method with background fluorescence quenching was developed for quantitative measurement of H-FABP in serum. The optimal concentrations of control for coating the test and control lines were determined as well as the concentrations of gold-labeled antibodies used in preparing the detection system. The detection method for H-FABP in serum was established and validated using real-world clinical samples.

Results

The optimal concentrations of labeling antibody and coating antibody were 5.0 μg/mL and 1.0 mg/mL, respectively. The test card had a sensitivity of 1.15 ng/mL over a linear concentration range of 0–100 ng/mL. Based on three batches prepared for testing the card, the relative standard deviation (RSD) within batches was less than 15% without a significant difference (P=0.942). The detection method was tested against common interfering substances in serum, such as bilirubin, triglyceride and serum anticoagulants ethylenediamine tetraacetic acid (EDTA), heparin, and sodium citrate, and no significant cross-reaction was detected. The test method was further validated with 50 clinical serum samples, and the test results were comparable with standard reference detection methods with good correlation (R=0.95).

Conclusion

Our study presents a new method with strong specificity and sensitivity for the detection of H-FABP in serum, which could promote H-FABP detection in a broad range of applications.

Asymmetric dimethylarginine and heart-type fatty acid-binding protein 3 are risk markers of cardiotoxicity in carbon monoxide poisoning cases in Zagazig university hospitals

Carbon monoxide (CO) poisoning is a leading cause of toxicity-related mortality and morbidity worldwide. Recent studies focused on CO-induced cardiovascular toxicity. Oxidative stress plays an important role in the pathophysiology of CO toxicity. The aim of this study was to elucidate the relationship between cardiac damage biomarkers and oxidative stress biomarkers in patients with CO-induced cardiotoxicity. This study was carried out on 36 CO-poisoned patients admitted to Zagazig University Hospitals. Forty healthy individuals (age- and sex-matched) were selected as a control group. Clinical examination and electrocardiography (ECG) were performed for CO-poisoned patients. These patients have been investigated for carboxyhaemoglobin percent (COHB%) and cardiac damage biomarkers; cardiac troponin I (cTn-I), heart-type fatty acid-binding protein 3 (H-FABP3). Oxidative stress biomarkers comprising malondialdehyde (MDA), asymmetric dimethylarginine (ADMA), and total antioxidant capacity (TAC) have been also assessed. All biomarkers have been assessed on admission (0 h) and 6 h after treatment of CO-poisoned patients with high-flow oxygen and compared with those of the control groups. ECG findings were abnormal in 31 patients (86.11%), where sinus tachycardia was the commonest finding (58.33%). There was a statistically significant increase of COHB%, MDA, ADMA, and H-FABP3 levels, and a significant decrease of TAC level in CO-poisoned patients compared to controls with no significant changes in cTn-I. Six hours following treatment, all measured parameters were significantly improved except for cTn-I, which was significantly increased when compared with admission status (0 h). Furthermore, H-FABP3 showed a significant positive correlation with COHB%, MDA, ADMA, and a negative correlation with TAC, while cTn-I was significantly correlated with COHB% only. ADMA and MDA seem to be the strongest determinants for the prediction of H-FABP3 changes and hence cardiovascular toxicity. Thus, cardiac damage in patients with CO poisoning could be partially mediated by CO-induced oxidative stress, where H-FABP3 level was directly and strongly associated with MDA and ADMA levels.

Rapidly rule out acute myocardial infarction by combining copeptin and heart-type fatty acid-binding protein with cardiac troponin

Background

The rapid exclusion of acute myocardial infarction in patients with chest pain can reduce the length of hospital admission, prevent unnecessary diagnostic work-up and reduce the burden on our health-care systems. The combined use of biomarkers that are associated with different pathophysiological aspects of acute myocardial infarction could improve the early diagnostic assessment of patients presenting with chest pain.

Methods

We measured cardiac troponin I, copeptin and heart-type fatty acid-binding protein concentrations in 584 patients who presented to the emergency department with acute chest pain. The diagnostic performances for the diagnosis of acute myocardial infarction and NSTEMI were calculated for the individual markers and their combinations. Separate calculations were made for patients presenting to the emergency department <3 h, 3–6 h and 6–12 h after chest pain onset.

Results

For ruling out acute myocardial infarction, the net predictive values (95% CI) of cardiac troponin I, copeptin and heart-type fatty acid-binding protein were 90.4% (87.3–92.9), 84% (79.8–87.6) and 87% (83.5–90), respectively. Combining the three biomarkers resulted in a net predictive value of 95.8% (92.8–97.8). The improvement was most pronounced in the early presenters (<3 h) where the combined net predictive value was 92.9% (87.3–96.5) compared to 84.6% (79.4–88.9) for cardiac troponin I alone. The area under the receiver operating characteristic for the triple biomarker combination increased significantly ( P < 0.05) compared to that of cardiac troponin I alone (0.880 [0.833–0.928] vs. 0.840 [0.781–0.898], respectively).

Conclusions

Combining copeptin, heart-type fatty acid-binding protein and cardiac troponin I measurements improves the diagnostic performance in patients presenting with chest pain. Importantly, in patients who present early (<3 h) after chest pain onset, the combination improves the diagnostic performance compared to the standard cardiac troponin I measurement alone.

Utility of Heart-type Fatty Acid Binding Protein as a New Biochemical Marker for the Early Diagnosis of Acute Coronary Syndrome

INTRODUCTION

Acute coronary syndrome (ACS) refers to a constellation of clinical symptoms caused by acute myocardial ischemia. Cardiovascular diseases (CVDs) are major and growing contributors to mortality and disability in India.

AIMS AND OBJECTIVES

Especially patients with non-ACS-related troponin elevations have an adverse outcome and require careful patient management. So, we look forward for another marker Heart-type Fatty Acid Binding Protein (H-FABP) that reliably detects myocardial ischemia in the absence of necrosis and would be useful for initial identification and for differentiating patients with chest pain of aetiology other than coronary ischemia.

MATERIALS AND METHODS

The study was done on 88 subjects of whom 34 subjects were with ischemic chest pain, 29 were with non-ischemic chest pain and 25 were normal subjects.

RESULTS

Receiver operating characteristic (ROC) curve analysis was done which showed that area under the curve (AUC) for H-FABP was 0.885(0.79-0.94) and that of high-sensitive Troponin T (hs-TnT) in initial six hours was 0.805(0.70-0.88). The specificity of H-FABP was higher compare to hs-TnT while sensitivity was comparable during 0-6 h of presentation of chest pain.

CONCLUSION

H-FABP can be used as an additional marker to hs-TnT in diagnosis of myocardial infarction (MI) and for exclusion of non-AMI (acute myocardial infarction) patients.

Pathophysiological roles and clinical importance of biomarkers in acute coronary syndrome

Early diagnosis of acute coronary syndrome (ACS) is important to guide appropriate therapy at a time when it is most likely to be of value. Accurate prognostic and risk stratification will facilitate high-risk patients to have early advanced diagnostic investigations and early appropriate interventions in a cost-effective and efficient manner, while those patients at low risk of ACS complications do not need such costly diagnostic tests and unnecessary hospital admission. Recent investigations have demonstrated that elevation of biomarkers upstream from acute-phase biomarkers, biomarkers of plaque destabilization and rupture, biomarkers of myocardial ischemia, necrosis, and dysfunction may provide an earlier assessment of patient risk and identify patients with higher risk of having an adverse event. This review provides an overview of the pathophysiology and clinical characteristics of several well-established biomarkers as well as emerging biomarkers that may have potential clinical utility in patients with ACS. Such emerging biomarkers hold promise and need to be more thoroughly evaluated before utilization in routine clinical practice.

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.

Heart fatty acid-binding protein in combination with the 80-lead body surface potential map improves early detection of acute myocardial infarction in patients who are cardiac troponin T-negative at presentation

Of patients who present with ischemic-type chest pain and a negative cardiac troponin T (cTnT) at first medical contact, there are patients at a very early stage of infarction. The aim of this research was to assess heart fatty acid-binding protein (H-FABP), a novel marker of myocyte necrosis, in combination with the 80-lead body surface potential map (BSPM) in the early diagnosis of acute myocardial infarction (AMI).

METHODS

In this prospective study, consecutive patients presenting with acute ischemic-type chest pain between 2003 and 2006 were enrolled. At first medical contact, blood was sampled for cTnT and H-FABP; in addition, a 12-lead electrocardiogram (ECG) and BSPM were recorded. A second cTnT was sampled 12 hours or more after presentation. Peak cTnT 0.03 μg/L or higher diagnosed AMI. Elevated H-FABP was 5 ng/mL or higher. A cardiologist blinded to both the clinical details and 12-lead ECG interpreted the BSPM.

RESULTS

Enrolled were 407 patients (age 62 ± 13 years; 70% men). Of these 407, 180 had cTnT less than 0.03 μg/L at presentation. Acute myocardial infarction occurred in 52 (29%) of 180 patients. Of these 180 patients, 27 had ST-segment elevation (STE) on ECG, 104 had STE on BSPM (sensitivity, 88%; specificity, 55%), and 95 (53%) had H-FABP elevation. The proportion with elevated H-FABP was higher in the AMI group compared with non-AMI group (P < .001). Body surface potential map STE was significantly associated with H-FABP elevation (P < .001). Of those with initial cTnT less than 0.03 μg/L, the c-statistic for the receiver operating characteristic curve distinguishing AMI from non-AMI using H-FABP alone was 0.644 (95% confidence interval [CI], 0.521-0.771), using BSPM alone was 0.716 (95% CI, 0.638-0.793), and using the combination of BSPM and H-FABP was 0.812 (95% CI, 0.747-0.876; P < .001).

CONCLUSION

In patients with acute ischemic-type chest pain who have a normal cTnT at presentation, the combination of H-FABP and BSPM at first assessment identifies those with early AMI (c-statistic, 0.812; P < .001), thus allowing earlier triage to reperfusion therapy and secondary prevention.

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.

Brain-specific fatty acid-binding protein is elevated in serum of patients with dementia-related diseases

BACKGROUND

There is a need for biomarkers in accessible matrices, such as blood, for the diagnosis of neurodegenerative diseases. The aim of this study was to measure the serum levels of brain-type fatty acid-binding protein (FABP) and heart-type FABP in patients with dementia-involving diseases.

METHODS

Brain- and heart-type FABP were measured in serum samples from patients with either Alzheimer's disease (AD) (n = 31), Parkinson's disease (PD, n = 43), or other cognitive disorders (OCD, n = 42) and in 52 healthy controls. The localization of brain- and heart-type FABP was determined in brain sections by immunohistochemistry.

RESULTS

Brain-type FABP levels were elevated in serum of 29%, 35%, and 24% of the patients with AD, PD, and OCD, respectively, and in 2% of the healthy donors. Heart-type FABP serum levels were not different amongst the patient groups. Brain-type and heart-type FABP expression was observed in reactive astrocytes in brain sections of patients with AD.

CONCLUSIONS

In contrast to heart-type FABP, serum levels of brain-type FABP are elevated in a significant proportion of patients with various neurodegenerative diseases and can therefore have importance for defining subgroups of these patients.

Fatty acid- and cholesterol transporter protein expression along the human intestinal tract

Background

Protein distribution profiles along the human intestinal tract of transporters involved in the absorption of cholesterol and long-chain fatty acids (LCFA) have been scarcely evaluated.

Methodology/Principal Findings

In post-mortem samples from 11 subjects, intestinal transporter distribution profiles were determined via Western Blot. Differences in transporter protein levels were statistically tested using ANOVA and Tukey's Post Hoc comparisons. Levels in all segments were expressed relative to those in duodenum. Except for ABCG5 and FATP4, levels (mean±SEM) were the highest in the ileum. For ABCA1, ileal levels (1.80±0.26) differed significantly from those in duodenum (P = 0.049) and proximal colon (0.92±0.14; P = 0.029). ABCG8 levels in ileum (1.91±0.30) differed from those in duodenum (P = 0.041) and distal colon (0.84±0.22; P = 0.010) and jejunum (1.64±0.26) tended to be higher than distal colon (0.84±0.22; P = 0.087). Ileal NPC1L1 levels (2.56±0.51) differed from duodenum levels (P = 0.019) and from distal colon (1.09±0.22; P = 0.030). There was also a trend (P = 0.098) for higher jejunal (2.23±0.37) than duodenal NPC1L1 levels. The levels of ABCG5 did not correlate with those of ABCG8. FAT/CD36 levels in ileum (2.03±0.42) differed from those in duodenum (P = 0.017), and proximal and distal colon (0.89±0.13 and 0.97±0.15 respectively; P = 0.011 and P = 0.014). FABPpm levels in ileum (1.04±0.13) differed from proximal (0.64±0.07; P = 0.026) and distal colon (0.66±0.09; P = 0.037).

Conclusions/Significance

The distribution profiles showed a bell-shape pattern along the GI-tract with the highest levels in ileum for ABCA1, ABCG8, NPC1L1, FATCD36 and FABPm, suggesting a prominent role for ileum in transporter-mediated uptake of cholesterol and LCFAs.

Cardiac biomarkers for risk stratification in non-massive pulmonary embolism: a multicenter prospective study

BACKGROUND

Troponins (cTnI and cTnT), N-terminal pro-Brain Natriuretic Peptide (NT-proBNP), myoglobin, heart-type fatty acid-binding protein (H-FABP) and fibrin D-Dimer are emergent candidates for risk stratification in pulmonary embolism (PE).

OBJECTIVE

To compare the respective prognostic values of biomarker with non-massive PE to predict an adverse outcome at 3 months.

PATIENTS/METHODS

One hundred and forty-six consecutive patients with non-massive PE were included in this multicenter prospective study. The combined outcome consisted of intensive care monitoring on admission, death or hospitalization attributable to either a PE-related complication [defined by PE/deep vein thrombosis (DVT) relapse or major bleeding under anticoagulation] or to dyspnoea with or without chest pain during follow-up.

RESULTS

The outcome was met in 12% of patients. In univariate analysis, a NT-proBNP level above 300 pg/ml was the strongest predictor of unfavorable outcome with an odds ratio (OR) of 15.8 [95% confidence interval (CI): 2.05-122). ORs for the other variables were: 8.0 for D-dimer >2000 ng/ml (95% CI: 1.1-64), 4.7 for H-FABP >6 ng/ml (95% CI:1.5-14.8), 3.5 for cTnI >0.09 ng/ml (95% CI:1.2-9.7), 3.4 for myoglobin >70 ng/ml (95% CI:0.9-12.2). Receiver operating curve (ROC) analysis indicated that NT-proBNP was the best predictor [area under the curve (AUC) 0.84; 95%CI: 0.76-0.92; P < 0.0001] with a negative predictive value of 100% (95% CI: 91-100) at 300 pg/ml. At that cut-off, the true negative rate for NT-proBNP was 40%. In multivariate analysis, NT-proBNP was the only significant independent predictors.

CONCLUSIONS

NT-proBNP appears to be a good risk stratification marker in identifying low-risk patients with non-massive PE who could be treated in an outpatient setting.

Prognostic value of a multimarker approach for patients presenting to hospital with acute chest pain

To evaluate the prognostic role of novel biomarkers for the risk stratification of patients admitted with ischemic-type chest pain, a prospective study of 664 patients presenting to 2 coronary care units with ischemic-type chest pain was conducted over 3 years beginning in 2003. Patients were assessed on admission for clinical characteristics, electrocardiographic findings, renal function, cardiac troponin T (cTnT), markers of myocyte injury (heart fatty acid-binding protein [H-FABP] and glycogen phosphorylase BB), neurohormonal activation (N-terminal-pro-brain natriuretic peptide [NT-pro-BNP]), hemostatic activity (fibrinogen and D-dimer), and vascular inflammation (high-sensitivity C-reactive protein, myeloperoxidase, matrix metalloproteinase-9, pregnancy-associated plasma protein-A, and soluble CD40 ligand). A >or=12-hour cTnT sample was also obtained. Myocardial infarction (MI) was defined as peak cTnT >or=0.03 microg/L. Patients were followed for 1 year from the time of admission. The primary end point was death or MI. Elevated fibrinogen, D-dimer, H-FABP, NT-pro-BNP, and peak cTnT were predictive of death or MI within 1 year (unadjusted odds ratios 2.5, 3.1, 5.4, 5.4, and 6.9, respectively). On multivariate analysis, H-FABP and NT-pro-BNP were selected, in addition to age, peak cTnT, and left ventricular hypertrophy on initial electrocardiography, as significant independent predictors of death or MI within 1 year. Patients without elevations of H-FABP, NT-pro-BNP, or peak cTnT formed a very low risk group in terms of death or MI within 1 year. A very high risk group had elevations of all 3 biomarkers. In conclusion, the measurement of H-FABP and NT-pro-BNP at the time of hospital admission for patients with ischemic-type chest pain adds useful prognostic information to that provided by the measurement of baseline and 12-hour cTnT.

Cardiac dysfunction and cell damage across clinical stages of severity in growth-restricted fetuses

OBJECTIVE

The purpose of this study was to assess cardiac function and cell damage in intrauterine growth-restricted (IUGR) fetuses across clinical Doppler stages of deterioration.

STUDY DESIGN

One hundred twenty appropriate-for-gestational-age and 81 IUGR fetuses were classified in stages 1/2/3 according umbilical artery present/absent/reversed end-diastolic blood flow, respectively. Cardiac function was assessed by modified-myocardial performance index, early-to-late diastolic filling ratios, cardiac output, and cord blood B-type natriuretic peptide; myocardial cell damage was assessed by heart fatty acid-binding protein, troponin-I, and high-sensitivity C-reactive protein.

RESULTS

Modified-myocardial performance index, blood B-type natriuretic peptide, and early-to-late diastolic filling ratios were increased in a stage-dependent manner in IUGR fetuses, compared with appropriate-for-gestational-age fetuses. Heart fatty acid-binding protein levels were higher in IUGR fetuses at stage 3, compared with control fetuses. Cardiac output, troponin-I, and high-sensitivity C-reactive protein did not increase in IUGR fetuses at any stage.

CONCLUSION

IUGR fetuses showed signs of cardiac dysfunction from early stages. Cardiac dysfunction deteriorates further with the progression of fetal compromise, together with the appearance of biochemical signs of cell damage.

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.

Improved assay of cardiac troponin I is more sensitive than other assays of necrosis markers

OBJECTIVE

Highly sensitive and specific assays of cardiac troponins I and T are the preferred biomarkers in diagnosing myocardial infarction (MI). Assays of cardiac troponin I (cTnI) have been improved with the addition of antibodies against the cTnI molecule and may have increased sensitivity. We hypothesized that a cTnI assay with modern antibody configuration will exhibit equal or better sensitivity in the setting of acute MI compared to cTnT and other markers of myocardial necrosis.

MATERIAL AND METHODS

We investigated release kinetics of cTnI (Abbott ADV, Abbott Diagnostics), cTnT (Roche Diagnostics), CKMBmass, myoglobin and heart fatty acid binding protein (H-FABP) in 23 patients admitted with acute ST-segment elevation MI undergoing primary percutaneous coronary intervention. Calibrators for the Abbott ADV cTnI assay are traceable to the United States National Institute of Standards and Technology (NIST) reference material for cTnI. Eleven blood samples were drawn from each patient in the period from admission to 24 h. Biomarkers of necrosis showed marked increases in relative concentrations, especially within the first 2 h after admission.

RESULTS

From 30 min after admission onwards, cTnI exhibited significantly higher relative concentrations compared to cTnT, CKMBmass, Myoglobin and H-FABP (p<0.05).

CONCLUSIONS

The NIST standardized Abbott TnI ADV assay appears to be more sensitive than cTnT and other biomarkers in the early phase of MI.

Serum heart-type fatty acid-binding protein and cerebrospinal fluid tau: marker candidates for dementia with Lewy bodies

BACKGROUND

The measurement of biomarkers in cerebrospinal fluid (CSF) has gained increasing acceptance in establishing the diagnosis of some neurodegenerative diseases. Heart-type fatty acid-binding protein (H-FABP) was recently discovered in CSF and serum of patients with neurodegenerative diseases.

OBJECTIVE

We investigated H-FABP in CSF and serum alone and in combination with CSF tau protein to evaluate these as potential biomarkers for the differentiation between dementia with Lewy bodies (DLB) and Alzheimer's disease (AD).

METHODS

We established H-FABP and tau protein values in a set of 144 persons with DLB (n = 33), Parkinson disease with dementia (PDD; n = 25), AD (n = 35) and nondemented neurological controls (NNC; n = 51). Additionally, serum H-FABP levels were analyzed in idiopathic Parkinson disease patients without evidence of cognitive decline (n = 45) using commercially available enzyme-linked immunosorbent assays. We calculated absolute values of H-FABP and tau protein in CSF and serum and established relative ratios between the two to obtain the best possible match for the clinical working diagnosis.

RESULTS

Serum H-FABP levels were elevated in DLB and PDD patients compared with NNC and AD subjects. To better discriminate between DLB and AD, we calculated the ratio of serum H-FABP to CSF tau protein levels. At the arbitrary chosen cutoff ratio > or =8 this quotient reached a sensitivity of 91% and a specificity of 66%.

CONCLUSION

Our results suggest that the measurement of CSF tau protein, together with H-FABP quantification in serum and CSF, and the ratio of serum H-FABP to CSF tau protein represent marker candidates for the differentiation between AD and DLB.

New Trends in Immunoassays

This article takes a special focus on signal amplification technologies in immunoassays and new generations of lateral-flow assays. Novel signal amplification technologies based either on new classes of biofunctional nanocrystals consisting of releasable fluorophores or on aggregation-induced emission (AIE) can improve the sensitivity and the limits of detection in immunoassays. A bio-barcode assay also allows signal amplification by utilizing antibody-coated magnetic beads to concentrate the analytes and antibody-coated gold nanoparticle probes to carry with a large number of oligonucleotides. These innovative technologies boost the development of immunoassays. Growth in rapid immunoassay is fueled by the increasing number of diabetics, the globalization of infectious diseases and the surge in cardiovascular and other chronic diseases as well as other chronic conditions. Rapid, near patient, decentralized, point-of-care (POC) tests are emerging as a tool for more efficient diagnosis and patient evaluation. Technological innovations in lateral-flow assays have enabled a move to bring testing closer to the patient. A novel "digital-style" lateral-flow assay provides semi-quantitative results by simply counting the number of red lines in the test without any expensive reading instrument. An immuno-threshold-based assay can give a signal directly proportional to the concentration of a hapten to prevent confusion on interpretation of the test results. In addition, POC tests become more meaningful to healthcare professionals by combining the benefits of new technologies to provide quantitative results. A molecular compact disc provides a high-resolution imaging capability that can identify and quantify many different antigens simultaneously in highly complex immunoassays. Further advances in immunoassays will bring diagnostic testing even closer to the patient, and can help physicians to monitor diseases that require immediate test results, thereby enhancing the quality of patient care.

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.

FABP3 and FABP10 in Atlantic salmon (Salmo salar L.)--general effects of dietary fatty acid composition and life cycle variations

The increased use of dietary plant oil supplementation combined with high dietary lipid loads challenges the lipid transport systems of cultivated fish species. Fatty acid binding proteins (FABPs) have been thoroughly studied as intracellular fatty acid transporters in vertebrates, but no data have been reported in Atlantic salmon. In the present study, comparative characterizations were performed, and dietary influence of plant oil supplementation on FABP3 and FABP10 expression was studied for several tissues in two separate dietary trials. In trial I, groups (6 fish each) were fed diets for 42 weeks (body mass 142+/-1 to 1463+/-83 g) (mean+/-S.D.), containing graded levels of rapeseed oil substituting for fish oil using a linear regression design. In trial II, groups (3 fish each) were fed 100% fish oil or 100% plant oil for 22 months (0.160+/-0.052 to 2523+/-590 g) (mean+/-S.D.) and sampled at regular intervals. Liver and muscle tissues appeared to express several FABPs possibly linked to different metabolic functions. FABPs mRNA expression did not change with dietary inclusion of 75% rapeseed oil, whereas FABP3 protein expression seemed to be affected by dietary rapeseed oil inclusion. Significant changes in red muscle FABP3 mRNA expression correlate to significant changes in total beta-oxidation capacity during the energy consuming process of smoltification.

Ischemia-reperfusion injury in cadaveric nonheart beating, cadaveric heart beating and live donor renal transplants

PURPOSE

Ischemia-reperfusion injury is gaining importance in transplantation as being responsible for allograft dysfunction. Ischemia occurs during kidney procurement, which is shortest in LDs, and prolonged in cadaveric HBDs and NHBDs.

MATERIALS AND METHODS

Renal transplants from 17 LDs, 15 HBDs and 19 NHBDs were assessed during reperfusion for biochemical markers of ischemia-reperfusion injury and assessed clinically. Central venous blood sampling was assayed for free radicals using electron spin resonance and tissue injury biomarkers, namely lactate dehydrogenase, fatty acid binding protein, alanine aminopeptidase, lactate and total antioxidants.

RESULTS

The return to stable renal function was more rapid in LD renal transplants, while recovery continued from 3 months after hospital discharge in NHBD renal transplants. Injury markers, such as lactate dehydrogenase, fatty acid binding protein, alanine aminopeptidase and lactate, were raised at the time of reperfusion, especially in NHBD renal transplants. Free radical release measured by electron spin resonance showed 2 phase release, that is early (0 to 10-minute) and late (20 to 40-minute) release. In NHBD, HBD and LD renal transplants the index of free radical release in the early phase was 1.43, 1.36 and 1.20, and in the late phase it was 1.43, 1.38 and 0.97, respectively (each ANOVA p <0.05).

CONCLUSIONS

NHBD renal transplants were accompanied by a greater release of free radicals at reperfusion (NHBD > HBD > LD), which was associated with an increase in tissue injury markers at reperfusion. This was reflected in a slower return to stable renal function in NHBD compared to HBD and LD renal transplants.

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.

State and diagnostic value of plasma tissue factor in early-hospitalised patients with chest pain

To study the state and diagnostic value of plasma tissue factor (TF) in patients with acute coronary syndromes (ACS), we quantitatively compared plasma TF antigen and TF activity in 90 early-hospitalised patients with chest pain. Using high-affinity antibodies, a sensitive assay for TF antigen was developed with a detection limit of 40 fmol/l. One of the antibodies was used to capture TF from plasma and, after elution and dialysis-free reconstitution in phospholipid-glucoside micelles, absolute amounts of TF activity could be measured with a detection limit of 80 fmol/l. All TF in plasma was found to be exposed, and a value of 2.5(1.1-14.8) pmol/l (median with range) was found for TF antigen. Most of this TF antigen (70-80%) circulated in a (potentially) functional state. Left in its in vivo state, however, TF captured from plasma was totally inactive, probably because of the lack of a procoagulant matrix. Compared with controls with non-cardiac chest pain, TF activity was unchanged and TF antigen about 25% elevated in ACS patients. Combined with the markers prothrombin fragment F1+2 and fatty acid-binding protein, TF did not improve the early diagnosis 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.

A continuous displacement immunoassay for human heart-type fatty acid-binding protein in plasma

Human heart-type fatty acid-binding protein (FABP) is suggested as an early plasma marker of acute myocardial infarction (AMI), and several studies have proved that, for early diagnosis of AMI, FABP performs better than myoglobin, which is a more often used early marker protein. Because serial measurement of biochemical markers in plasma is now universally accepted as an important determinant in AMI diagnosis, a rapid and continuous measuring method for FABP would be desirable. The aim of the present study was to develop an immunoassay based on the principle of displacement and using a column for rapid and continuous measurement of FABP in plasma. Glass columns filled with Sepharose-bound FABP were loaded with a horseradish peroxidase (HRP)-labeled antibody (Ab) and equilibrated with human plasma. After reaching a stable baseline, human plasma spiked with FABP or plasma from AMI patients was added. The Ab-HRP complex dissociated due to the presence of FABP in the plasma and was subsequently quantified. For plasma from AMI patients (n=5), the Ab-HRP level thus measured correlated with the corresponding plasma FABP concentration (R=0.96). The results of this study show the feasibility of a sensor for continuous monitoring of FABP in plasma.

Brain- and Heart-Type Fatty Acid-Binding Proteins in the Brain: Tissue Distribution and Clinical Utility

Background: Detection of brain injury by serum markers is not a standard procedure in clinical practice, although several proteins, such as S100B, neuron-specific enolase (NSE), myelin basic protein, and glial fibrillary acidic protein, show promising results. We investigated the tissue distribution of brain- and heart-type fatty acid-binding proteins (B-FABP and H-FABP) in segments of the human brain and the potential of either protein to serve as plasma marker for diagnosis of brain injury.

Methods: B-FABP and H-FABP were measured immunochemically in autopsy samples of the brain (n = 6) and in serum samples from (a) patients with mild traumatic brain injury (MTBI; n = 130) and (b) depressed patients undergoing bilateral electroconvulsive therapy (ECT; n = 14). The protein markers S100B and NSE were measured for comparison. Reference values of B-FABP and H-FABP were established in healthy individuals (n = 92).

Results: The frontal, temporal, and occipital lobes, the striatum, the pons, and the cerebellum had different tissue concentrations of B-FABP and of H-FABP. B-FABP ranged from 0.8 μg/g wet weight in striatum tissue to 3.1 μg/g in frontal lobe. H-FABP was markedly higher, ranging from 16.2 μg/g wet weight in cerebellum tissue to 39.5 μg/g in pons. No B-FABP was detected in serum from healthy donors. H-FABP serum reference value was 6 μg/L. In the MTBI study, serum B-FABP was increased in 68% and H-FABP in 70% of patients compared with S100B (increased in 45%) and NSE (increased in 51% of patients). In ECT, serum B-FABP was increased in 6% of all samples (2 of 14 patients), whereas H-FABP was above its upper reference limit (6 μg/L) in 17% of all samples (8 of 14 patients), and S100B was above its upper reference limit (0.3 μg/L) in 0.4% of all samples.

Conclusions: B-FABP and H-FABP patterns differ among brain tissues, with the highest concentrations in the frontal lobe and pons, respectively. However, in each part of the brain, the H-FABP concentration was at least 10 times higher than that of B-FABP. Patient studies indicate that B-FABP and H-FABP are more sensitive markers for minor brain injury than the currently used markers S100B and NSE.

Intestinal-type and liver-type fatty acid-binding protein in the intestine. Tissue distribution and clinical utility

OBJECTIVES

Intestinal-type fatty acid-binding protein (I-FABP) has been proposed as plasma marker for the detection of acute intestinal injury. However, intestinal mucosa also expresses liver-type FABP (L-FABP). We have investigated the tissue distribution of I-FABP and L-FABP in segments of the human intestine along the duodenal to colonal axis and the potential of both proteins to serve as plasma marker for the diagnosis of intestinal injury.

DESIGN AND METHODS

I-FABP and L-FABP were measured with specific immunoassays in autopsy samples of the intestine (duodenum, jejunum, ileum and colon) of 23 subjects and in plasma samples from patients (n = 51) with intestinal and/or hepatic disease. Plasma reference values were established in normal healthy individuals (n = 92).

RESULTS

The I-FABP tissue contents in duodenum, jejunum, ileum, proximal colon and distal colon amounted to 2.22, 4.79, 1.04, 0.27 and 0.25 mug/g ww, respectively. L-FABP tissue contents were markedly higher, amounting to 124 and 198 mug/g ww in duodenum and jejunum, and to 58, 26 and 44 mug/g ww in ileum, proximal colon and distal colon, respectively. Elevated plasma levels of both I-FABP and L-FABP were found in patients suffering from intestinal diseases, while only L-FABP was increased in cases of purely hepatocellular injury.

CONCLUSIONS

I-FABP and L-FABP show a similar pattern of tissue distribution along the duodenal to colonal axis with highest tissue contents found in the jejunum but in each intestinal segment a >40-fold higher content of L-FABP than of I-FABP. Accordingly, besides I-FABP, also L-FABP is a useful plasma marker for the detection of intestinal injury, especially in patients undergoing intestinal 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.