The amino-terminal portion of pro-brain natriuretic peptide (Pro-BNP) circulates in human plasma

Turning Antibodies into Ratiometric Bioluminescent Sensors for Competition-Based Homogeneous Immunoassays

Here we present LUCOS (Luminescent Competition Sensor), a modular and broadly applicable bioluminescent diagnostic platform enabling the detection of both small molecules and protein biomarkers. The construction of LUCOS sensors entails the covalent and site-specific coupling of a bioluminescent sensor component to an analyte-specific antibody via protein G-mediated photoconjugation. Target detection is accomplished through intramolecular competition with a tethered analyte competitor for antibody binding. We established two variants of LUCOS: an inherent ratiometric LUCOSR variant and an intensiometric LUCOSI version, which can be used for ratiometric detection upon the addition of a split calibrator luciferase. To demonstrate the versatility of the LUCOS platform, sensors were developed for the detection of the small molecule cortisol and the protein biomarker NT-proBNP. Sensors for both targets displayed analyte-dependent changes in the emission ratio and enabled detection in the micromolar concentration range (KD,app = 16-92 μM). Furthermore, we showed that the response range of the LUCOS sensor can be adjusted by attenuating the affinity of the tethered NT-proBNP competitor, which enabled detection in the nanomolar concentration range (KD,app = 317 ± 26 nM). Overall, the LUCOS platform offers a highly versatile and easy method to convert commercially available monoclonal antibodies into bioluminescent biosensors that provide a homogeneous alternative for the competitive immunoassay.

Review A State of Natriuretic Peptide Deficiency

Measurement of natriuretic peptides (NPs) has proven its clinical value as biomarker, especially in the context of heart failure (HF). In contrast, a state partial NP deficiency appears integral to several conditions in which lower NP concentrations in plasma presage overt cardiometabolic disease. Here, obesity and type 2 diabetes have attracted considerable attention. Other factors - including age, sex, race, genetics, and diurnal regulation - affect the NP "armory" and may leave some individuals more prone to development of cardiovascular disease. The molecular maturation of NPs has also proven complex with highly variable O-glycosylation within the biosynthetic precursors. The relevance of this regulatory step in post-translational propeptide maturation has recently become recognized in biomarker measurement/interpretation and cardiovascular pathophysiology. An important proportion of people appear to have reduced effective net NP bioactivity in terms of receptor activation and physiological effects. The state of NP deficiency, then, both entails a potential for further biomarker development and could also offer novel pharmacological possibilities. Alleviating the state of NP deficiency before development of overt cardiometabolic disease in selected patients could be a future path for improving precision medicine.

Biochemistry of the Endocrine Heart

Simple Summary

Besides being a muscle and an electrochemically active organ, the heart is a true endocrine organ. As endocrine cells, cardiac myocytes possess all the needed chemical necessities for translation, post-translational modifications, and complex peptide proteolysis. In addition, intracellular granules in the cells contain not only peptides destined for secretion but also important granin molecules involved in maintaining a regulated secretory pathway. In this review, we highlight the biochemical phenotype of the endocrine heart, recapitulating that the cardiac myocytes are truly and fully capable endocrine cells.

Abstract

Production and release of natriuretic peptides and other vasoactive peptides are tightly regulated in mammalian physiology and involved in cardiovascular homeostasis. As endocrine cells, the cardiac myocytes seem to possess almost all known chemical necessities for translation, post-translational modifications, and complex peptide proteolysis. In several ways, intracellular granules in the cells contain not only peptides destined for secretion but also important granin molecules involved in maintaining a regulated secretory pathway. In this review, we will highlight the biochemical phenotype of the endocrine heart recapitulating that the cardiac myocytes are capable endocrine cells. Understanding the basal biochemistry of the endocrine heart in producing and secreting peptides to circulation could lead to new discoveries concerning known peptide products as well as hitherto unidentified cardiac peptide products. In perspective, studies on natriuretic peptides in the heart have shown that the post-translational phase of gene expression is not only relevant for human physiology but may prove implicated also in the development and, perhaps one day, cure of human cardiovascular disease.

Flow reduction of a high-flow arteriovenous fistula in a hemodialysis patient reveals changes in natriuretic and renin-angiotensin system hormones of relevance for kidney function

Arteriovenous fistulas (AVFs) are iatrogenic vascular connections established to allow high-flow intravascular access for patients with chronic kidney disease requiring hemodialysis. The left-right flow shunt results in changes in extracellular fluid volume and blood pressure-controlling hormones that could affect the residual kidney function. We present a case where a female patient with a brachiocephalic AVF had a fistula flow of >4 L/min. To reduce the flow, a banding procedure was performed. The patient was examined prior to banding and 1 and 2 weeks thereafter. Banding resulted in a marked decrease in AVF flow from >4 to 1 L/min and was associated with reductions in N-terminal pro-brain natriuretic peptide of 51% and 67% at 1- and 2-weeks post-banding, respectively. Mid-regional pro-atrial natriuretic peptide concentrations were reduced post-banding by 17% after 1 week and 25% after 2 weeks. After 1 week, renin, angiotensin II, and aldosterone levels in plasma decreased transiently by 44%, 47%, and >86%, respectively, and returned to pre-banding levels after 2 weeks. Creatinine clearance tended to decrease while blood pressure and total body water increased 2 weeks after banding. This indicates that high-flow AVF is associated with increased natriuretic peptides and hormones of the renin-angiotensin-aldosterone system, that may balance each other regarding fluid retention and hypertension and support remaining kidney function.

Right Ventricular Strain, Brain Natriuretic Peptide, and Mortality in Congenital Diaphragmatic Hernia

Rationale: Brain-type natriuretic peptide (BNP) correlates with pulmonary hypertension as demonstrated by echocardiogram in congenital diaphragmatic hernia (CDH); however, its association with right ventricular (RV) function and mortality is unknown.Objectives: To characterize the relationships between echocardiogram-derived RV strain, BNP, and mortality in diaphragmatic hernia.Methods: We performed a single-center retrospective cohort study of infants with CDH and at least one BNP-echocardiogram pair within a 24-hour period. RV global longitudinal strain (GLS) and free-wall strain (FWS) were measured on existing echocardiograms. Associations among strain, BNP, and mortality were tested using mixed-effect linear and logistic regression models. Survival analysis was stratified by BNP and strain abnormalities.Results: There were 220 infants with 460 BNP-echocardiogram pairs obtained preoperatively (n = 237), ≤1 week postoperatively (n = 35), and >1 week postoperatively ("recovery"; n = 188). Strain improved after repair (P < 0.0001 for all periods). Higher BNP level was associated with worse strain in recovery but not before or immediately after operation (estimate [95% confidence interval] for recovery: GLS, 1.03 [0.50-1.57]; P = 0.0003; FWS, 0.62 [0.01-1.22]; P = 0.047). BNP and strain abnormalities were associated with an extracorporeal-membrane oxygenation requirement. Higher BNP level in recovery was associated with greater mortality (odds ratio, 11.2 [1.2-571.3]; P = 0.02). Abnormal strain in recovery had high sensitivity for detection of mortality (100% for GLS; 100% for FWS) but had low specificity for detection of mortality (28% for GLS; 48% for FWS).Conclusions: Persistent RV dysfunction after CDH repair may be detected by a high BNP level and abnormal RV strain.

The Role of Neprilysin Inhibitors in the Treatment of Heart Failure with Preserved Ejection Fraction

Clinical and hemodynamic aggravation of heart failure with preserved ejection fraction (HFpEF) is largely due to progression of left ventricular (LV) diastolic dysfunction. The key role in the normal maintenance of diastolic function is played by a high level of activity of the intracellular signaling axis, cyclic guanosine-monophosphate-protein kinase G, the activity of which is significantly reduced in HFpEF. The activity of this axis can be increased by increasing the bioavailability of natriuretic peptides by blocking the enzyme neutral endopeptidase (neprilisin), which is responsible for the destruction of natriuretic peptides.This review presents experimental and clinical data on the use of neprilysin inhibitors in HFpEF and addresses prospects of this treatment.

B-Type Natriuretic Peptide as a Significant Brain Biomarker for Stroke Triaging Using a Bedside Point-of-Care Monitoring Biosensor

Stroke is a widespread condition that causes 7 million deaths globally. Survivors suffer from a range of disabilities that affect their everyday life. It is a complex condition and there is a need to monitor the different signals that are associated with it. Stroke patients need to be rapidly diagnosed in the emergency department in order to allow the admission of the time-limited treatment of tissue plasminogen activator (tPA). Stroke diagnostics show the use of sophisticated technologies; however, they still contain limitations. The hidden information and technological advancements behind the utilization of biomarkers for stroke triaging are significant. Stroke biomarkers can revolutionize the way stroke patients are diagnosed, monitored, and how they recover. Different biomarkers indicate different cascades and exhibit unique expression patterns which are connected to certain pathologies in the human body. Over the past decades, B-type natriuretic peptide (BNP) and its derivative N-terminal fragment (NT-proBNP) have been increasingly investigated and highlighted as significant cardiovascular biomarkers. This work reviews the recent studies that have reported on the usefulness of BNP and NT-proBNP for stroke triaging. Their classification association is also presented, with increased mortality in stroke, correlation with cardioembolic stroke, and an indication of a second stroke recurrence. Moreover, recent scientific efforts conducted for the technological advancement of a bedside point-of-care (POC) device for BNP and NT-proBNP measurements are discussed. The conclusions presented in this review may hopefully assist in the major efforts that are currently being conducted in order to improve the care of stroke patients.

BNP as a New Biomarker of Cardiac Thyroid Hormone Function

Background

Cardiac re-expression of fetal genes in patients with heart failure (HF) suggests the presence of low cardiac tissue thyroid hormone (TH) function. However, serum concentrations of T3 and T4 are often normal or subclinically low, necessitating an alternative serum biomarker for low cardiac TH function to guide treatment of these patients. The clinical literature suggests that serum Brain Natriuretic Peptide (BNP) levels are inversely associated with serum triiodo-L-thyronine (T3) levels. The objective of this study was to investigate BNP as a potential serum biomarker for TH function in the heart.

Methods

Two animal models of thyroid hormone deficiency: (1) 8-weeks of propyl thiouracil-induced hypothyroidism (Hypo) in adult female rats were subsequently treated with oral T3 (10 μg/kg/d) for 3, 6, or 14 days; (2) HF induced by coronary artery ligation (myocardial infarction, MI) in adult female rats was treated daily with low dose oral T3 (5 μg/kg/d) for 8 or 16 wks.

Results

Six days of T3 treatment of Hypo rats normalized most cardiac functional parameters. Serum levels of BNP increased 5-fold in Hypo rats, while T3 treatment normalized BNP by day 14, showing a significant inverse relationship between serum BNP and free or total T3 concentrations. Myocardial BNP mRNA was increased 2.5-fold in Hypo rats and its expression was decreased to normal values by 14 days of T3 treatment. Measurements of hemodynamic function showed significant dysfunction in MI rats after 16 weeks, with serum BNP increased by 4.5-fold and serum free and total T3 decreased significantly. Treatment with T3 decreased serum BNP while increasing total T3 indicating an inverse correlation between these two biologic factors (r ² = 0.676, p < 0.001). Myocardial BNP mRNA was increased 5-fold in MI rats which was significantly decreased by T3 over 8 to 16 week treatment periods.

Conclusions

Results from the two models of TH dysfunction confirmed an inverse relationship between tissue and serum T3 and BNP, such that the reduction in serum BNP could potentially be utilized to monitor efficacy and dosing of T3 treatment. Thus, serum BNP may serve as a reliable biomarker for cardiac TH function.

Point-of-Care Surface Plasmon Resonance Biosensor for Stroke Biomarkers NT-proBNP and S100β Using a Functionalized Gold Chip with Specific Antibody

Surface-plasmon-resonance (SPR) is a quantum-electromagnetic phenomenon arising from the interaction of light with free electrons at a metal-dielectric interface. At a specific angle/wavelength of light, the photon's energy is transferred to excite the oscillation of the free electrons on the surface. A change in the refractive-index (RI) may occur, which is influenced by the analyte concentration in the medium in close contact with the metal surface. SPR has been widely used for the detection of gaseous, liquid, or solid samples. In this study, a functionalized specific SPR chip was designed and used in a novel point-of-care SPR module (PhotonicSys SPR H5) for the detection of the stroke biomarkers NT-proBNP and S100β. These biomarkers have proven to be good for stroke diagnosis, with sensitivity and specificity of >85%. Specific detection was done by binding a biomolecular-recognizing antibody onto the Au SPR-chip. Detection was tested in water and plasma samples. NT-proBNP and S100β were detected in a range of concentrations for stroke, from 0.1 ng/mL to 10 ng/mL. The RI of the blank plasma samples was 1.362412, and the lowest concentration tested for both biomarkers showed a prominent shift in the RI signal (0.25 ng/mL NT-proBNP (1.364215) and S100β (1.364024)). The sensor demonstrated a clinically relevant limit-of-detection of less than ng/mL.

The Predictivity of N-Terminal Pro b-Type Natriuretic Peptide for All-Cause Mortality in Various Follow-Up Periods among Heart Failure Patients

Plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) is an excellent prognostic–predictive tool in heart failure (HF) patients, but its plasma level changes following therapy. The comparison of prognosis–predictivity of a single measurement of plasma NT-pro BNP in different follow-up periods in acute HF patients has been less studied. This study aimed to evaluate whether the association between initial plasma NT-proBNP levels and all-cause mortality would decrease along with an increased follow-up period in patients with acute HF. The retrospective study was carried out, enrolling adult patients with hospitalization-requiring acute HF who fulfilled the predefined criteria from January 1, 2011, to December 31, 2013. We evaluated the independent predictors of 12-month mortality, and subsequently compared the predictivity of NT-proBNP level at initial presentation for 1-, 3-, 6-, 9- and 12-month mortality. In total, 269 patients (mean age, 74.45 ± 13.59 years; female, 53.9%) were enrolled. The independent predictors of 12-month mortality included higher “Charlson Comorbidity Index” (adjusted hazard ratio (aHR) = 1.22; 95% confidence interval (CI), 1.10–1.34), increased “age” (aHR = 1.07; 95% CI, 1.04–1.10), “administration of vasopressor” (aHR = 3.43; 95% CI, 1.76–6.71), “underwent cardiopulmonary resuscitation” (aHR = 4.59; 95% CI, 1.76–6.71), and without “angiotensin-converting enzyme inhibitors/angiotensin receptor blocker” (aHR = 0.41; 95% CI, 1.86–11.31) (all p <0.001). “Plasma NT-pro BNP level ≧11,755 ng/L” was demonstrated as an independent predictor in 1-month (aHR = 2.37; 95% CI, 1.10–5.11; p = 0.028) and 3-month mortality (aHR = 1.98; 95% CI, 1.02–3.86; p = 0.045) but not in more extended follow-up. The outcome predictivity of plasma NT-proBNP levels diminished in a longer follow-up period in hospitalized acute HF patients. In conclusion, these findings remind physicians to act with caution when using a single plasma level of NT-proBNP to predict patient outcomes with a longer follow-up period.

The level of NT-proBNP in ambulatory patients with chronic heart failure with preserved ejection fraction of the left ventricle

AIM

The prevalence of chronic heart failure (CHF) remains high. Echocardiography is a reliable method of diagnosing heart failure. Determination of brain natriuretic peptide allows to identify patients with the most probable diagnosis of heart failure, which requires further instrumental examination of patients. To study the level of the brain natriuretic peptide in patients with diastolic chronic heart failure with preserved left ventricular ejection fraction.

MATERIALS AND METHODS

The study included 96 outpatients with diastolic chronic heart failure I-III functional class with a preserved left ventricular ejection fraction at the age of 65.06 ± 1.15 years and 50 practically healthy people aged 39.90 ± 1.64 years as a control group who underwent a preventive examination. The level of the N-terminal fragment of the medullary natriuretic peptide (NT-proBNP) in serum was determined using a test system (Vector-Best, Russia).

RESULTS

The concentration of NT-proBNP in patients with diastolic heart failure with a preserved left ventricular ejection fraction was 108.18 ± 21.64 in the range from 0.0 to 1212.3 pg/ml compared to the control of 7.6 ± 1.38 pg/ml, p<0.05. A positive correlation was found between the concentration of NT-proBNP and the area of the left atrium (r=0.35), left ventricular E/e '(r=0.6), and left ventricular end-systolic volume (r=0.48). The level of NT-proBNP had no correlation with the functional class of CHF (r=0,23), as well as with the stage of CHF (r=0,23).

CONCLUSION

Thus, patients with diastolic CHF with a preserved ejection fraction in 67% of cases had a level of NT-proBNP in the blood less than the diagnostic threshold. The concentration of NT-proBNP in the serum positively correlates with increased pressure in the cavity of the left ventricle, the end-systolic volume in it and the area of the left atrium.

Accuracy of Brain Natriuretic Peptide for Diagnosing Pulmonary Hypertension in Severe Bronchopulmonary Dysplasia

BACKGROUND

Premature infants with severe bronchopulmonary dysplasia (sBPD) are at risk of pulmonary hypertension (PH). Serum brain natriuretic peptide (BNP) is used to predict disease severity in adult PH. Its diagnostic utility in sBPD-associated PH is unknown.

OBJECTIVE

The aim of this paper was to determine the accuracy of BNP, against echocardiogram (echo), to diagnose PH in infants born <32 weeks' gestation with sBPD.

METHODS

We conducted a retrospective cohort study of all infants with sBPD with an echo and BNP within a 24-h period, at ≥36 weeks postmenstrual age. PH was defined as: right ventricular pressure >½ systemic blood pressure estimated from tricuspid regurgitant jet or patent ductus arteriosus (PDA) velocity, bidirectional or right-to left-PDA, and/or flat/bowing ventricular septum at end-systole. Receiver-operating characteristic (ROC) curves were constructed to test the diagnostic accuracy of BNP.

RESULTS

Of 128 infants, 68 (53%) had echo evidence of PH. BNP was higher among the infants with PH (median [interquartile range]: 127 pg/mL [39-290] vs. 35 [20-76], p < 0.001). The area under the ROC curve for diagnosing PH using BNP was 0.74 (95% CI 0.66-0.83). At an optimal cutpoint of 130 pg/mL, BNP correctly classified the presence or absence of PH in 70% of the infants (specificity: 92, sensitivity: 50%).

CONCLUSIONS

BNP, relative to concurrent echo, demonstrated moderate accuracy for diagnosing PH in this cohort of preterm infants with sBPD. BNP may help rule in PH in this population but has low utility to rule out the disease.

N-Terminal pro C-Type Natriuretic Peptide (NTproCNP) and myocardial function in ageing

Ageing-related alterations in cardiovascular structure and function are commonly associated with chronic inflammation. A potential blood-based biomarker indicative of a chronic inflammatory state is N-Terminal Pro C-Type Natriuretic Peptide (NTproCNP). We aim to investigate associations between NTproCNP and ageing-related impairments in cardiovascular function. Community-based participants underwent same-day assessment of cardiovascular function and circulating profiles of plasma NTproCNP. Associations between cardiovascular and biomarker profiles were studied in adjusted models including standard covariates. We studied 93 participants (mean age 73 ± 5.3 years, 36 women), of whom 55 (59%) had impaired myocardial relaxation (ratio of peak velocity flow in early diastole E (m/s) to peak velocity flow in late diastole by atrial contraction A (m/s) <0.84). Participants with impaired myocardial relaxation were also found to have lower peak early phase filling velocity (0.6 ± 0.1 vs 0.7 ± 0.1, p < 0.0001) and higher peak atrial phase filling velocity (0.9 ± 0.1 vs 0.7 ± 0.1, p < 0.0001). NTproCNP levelswere significantly lower among participants with impaired myocardial relaxation (16.4% vs 39.5% with NTproCNP ≥ 19, p = 0.012). After multivariable adjustments, NTproCNP was independently associated with impaired myocardial relaxation (OR 2.99, 95%CI 1.12–8.01, p = 0.029). Community elderly adults with myocardial ageing have lower NTproCNP levels compared to those with preserved myocardial function. Given that impaired myocardial relaxation probably represents early changes within the myocardium with ageing, NTproCNP may be useful as an ‘upstream’ biomarker useful for charting myocardial ageing.

Natriuretic Peptides and Normal Body Fluid Regulation

Natriuretic peptides are structurally related, functionally diverse hormones. Circulating atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are delivered predominantly by the heart. Two C-type natriuretic peptides (CNPs) are paracrine messengers, notably in bone, brain, and vessels. Natriuretic peptides act by binding to the extracellular domains of three receptors, NPR-A, NPR-B, and NPR-C of which the first two are guanylate cyclases. NPR-C is coupled to inhibitory proteins. Atrial wall stress is the major regulator of ANP secretion; however, atrial pressure changes plasma ANP only modestly and transiently, and the relation between plasma ANP and atrial wall tension (or extracellular volume or sodium intake) is weak. Absence and overexpression of ANP-related genes are associated with modest blood pressure changes. ANP augments vascular permeability and reduces vascular contractility, renin and aldosterone secretion, sympathetic nerve activity, and renal tubular sodium transport. Within the physiological range of plasma ANP, the responses to step-up changes are unimpressive; in man, the systemic physiological effects include diminution of renin secretion, aldosterone secretion, and cardiac preload. For BNP, the available evidence does not show that cardiac release to the blood is related to sodium homeostasis or body fluid control. CNPs are not circulating hormones, but primarily paracrine messengers important to ossification, nervous system development, and endothelial function. Normally, natriuretic peptides are not powerful natriuretic/diuretic hormones; common conclusions are not consistently supported by hard data. ANP may provide fine-tuning of reno-cardiovascular relationships, but seems, together with BNP, primarily involved in the regulation of cardiac performance and remodeling. © 2017 American Physiological Society. Compr Physiol 8:1211-1249, 2018.

Prognostic and diagnostic significance of mid-regional pro-atrial natriuretic peptide in acute exacerbation of chronic obstructive pulmonary disease and acute heart failure: data from the ACE 2 Study

PURPOSE

To compare the diagnostic and prognostic value of mid-regional pro-ANP (MR-proANP) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) in patients with acute dyspnea.

METHODS

MR-proANP and NT-proBNP were measured with commercial immunoassays at hospital admission (n = 313), on day 2 (n = 234), and before discharge (n = 91) and compared for diagnosing acute heart failure (HF; n = 143) and to predict mortality among patients with acute HF and acute exacerbation of chronic obstructive pulmonary disease (AECOPD; n = 84) separately.

RESULTS

The correlation coefficient between MR-proANP and NT-proBNP was 0.89 (p < 0.001) and the receiver-operating area under the curve (AUC) was 0.85 (95% CI 0.81-0.89) for MR-proANP and 0.86 (0.82-0.90) for NT-proBNP to diagnose acute HF. During a median follow-up of 816 days, mortality rates were 46% in acute HF patients and 42% in AECOPD patients. After adjustment for other risk variables by multivariate Cox regression analysis, MR-proANP and NT-proBNP concentrations were associated with mortality in patients with acute HF, but only MR-proANP were associated with mortality among patients with AECOPD: hazard ratio (_lnMR-proANP) 1.98 (95% CI 1.17-3.34).

CONCLUSION

MR-proANP and NT-proBNP concentrations provide similar diagnostic and prognostic information in patients with acute HF. In contrast to NT-proBNP, MR-proANP measurements also provided independent prognostic information in AECOPD patients.

N-Terminal B-type Natriuretic Peptide in Heart Failure

Plasma amino-terminal pro-B-type natriuretic peptide (NT-proBNP) is a guideline-mandated biomarker in heart failure (HF). Used as an inclusion criterion for therapeutic trials, NT-proBNP enriches trial populations and is a valid surrogate endpoint. Its diagnostic performance is best validated in acute decompensated HF (ADHF). NT-proBNP offers prognostic information independent of standard clinical predictors and refines risk stratification. With the advent of combined angiotensin 2 type 1 receptor blockade and neprilysin inhibition (ARNI) NT-proBNP retains its relationship to cardiac status and is the marker of choice in assessment of possible ADHF and in serial monitoring of HF patients receiving ARNI treatment.

Standardization of BNP and NT-proBNP Immunoassays in Light of the Diverse and Complex Nature of Circulating BNP-Related Peptides

Brain natriuretic peptide (BNP) and the N-terminal fragment of the BNP precursor (NT-proBNP) are widely used as heart failure (HF) biomarkers. Since the discovery of BNP in 1988, much effort has been allocated to the precise detection of BNP and NT-proBNP levels for reliable HF diagnostics. As a result, measurements of these biomarkers are globally accepted and used in clinical practice for the diagnosis of acute and chronic HF, risk stratification, and monitoring response to therapy. Several immunoassays specific for BNP and NT-proBNP are currently commercially available. Recent comparative studies show that there are marked differences between different BNP and NT-proBNP assays and platforms, and the results of measurements are not comparable enough. The lack of equivalence between the assays complicates the interpretation of the results and renders the cut-off points for diagnostic decisions to be method dependent. Presently, there is no agreement on what kind of BNP or NT-proBNP standard should be used for calibration, and a certified reference material as well as reference measurement procedures are lacking. The aim of this chapter is to summarize the available data on the complex nature of BNP-related peptides, specificity for existing BNP and NT-proBNP immunoassays, and to discuss potential approaches for standardization of BNP and NT-proBNP measurements.

Molecular forms of C-type natriuretic peptide in cerebrospinal fluid and plasma reflect differential processing in brain and pituitary tissues

C-type natriuretic peptide (CNP) is a paracrine growth factor widely expressed within tissues of the central nervous system. Consistent with this is the high concentration of CNP in cerebrospinal fluid (CSF), exceeding levels in the systemic circulation. CNP abundance is high in hypothalamus and especially enriched in pituitary tissue where - in contrast to hypothalamus - processing to CNP-22 is minimal. Recently we have shown that dexamethasone acutely raises CNP peptides throughout the brain as well as in CSF and plasma. Postulating that molecular forms of CNP would differ in central tissues compared to forms in pituitary and plasma, we have characterized the molecular forms of CNP in tissues (hypothalamus, anterior and posterior pituitary gland) and associated fluids (CSF and plasma) using size-exclusion high performance liquid chromatography (SE-HPLC) and radioimmunoassay in control (saline-treated) and dexamethasone-treated adult sheep. Three immunoreactive-CNP components were identified which were consistent with proCNP (1-103), CNP-53 and CNP-22, but the presence and proportions of these different fragments differed among tissues. Peaks consistent with CNP-53 were the dominant form in all tissues and fluids. Peaks consistent with proCNP, conspicuous in hypothalamic extracts, were negligible in CSF whereas proportions of low molecular weight immunoreactivity (IR) consistent with CNP-22 were similar in hypothalamus, posterior pituitary gland and CSF. In contrast, in both plasma and the anterior pituitary gland, proportions of higher molecular weight IR, consistent with CNP-53 and proCNP, predominated, and low molecular weight IR consistent with CNP-22 was very low. After dexamethasone, proCNP like material - but not other forms - was increased in all samples except CSF, consistent with increased synthesis and secretion. In conclusion, immunoreactive forms of CNP in central tissues differ from those identified in anterior pituitary tissue and plasma - suggesting that the anterior pituitary gland may contribute to systemic levels of CNP in some physiological settings.

The role of N-terminal pro-brain natriuretic peptide in evaluating the prognosis of patients with intracerebral hemorrhage

A prognostic biomarker that can provide a good prediction of prognosis in patients with intracerebral hemorrhage (ICH) would be beneficial in guiding the initial management decisions in the setting of ICH. N-terminal pro-brain natriuretic peptide (NT-proBNP) is a biomarker of prognosis in patients with cardiovascular disease and ischemic stroke. However, the prognostic role of NT-proBNP in patients with spontaneous ICH is still a controversial issue. This study aimed to determine the prognostic value of NT-proBNP in patients with spontaneous ICH. A total of 132 patients from 571 ICH cases in inpatient settings were enrolled in this study. Blood samples from each subject were obtained and analyzed for NT-proBNP on admission and on days 4 and 7. The first end point was functional outcome at discharge, which was dichotomized into favorable or unfavorable; the secondary end point was mortality within 6 months after ICH. Compared with the baseline levels on admission after ICH, the NT-proBNP levels increased markedly on day 4 (P < 0.05). Multivariate logistic regression analysis indicated that the NT-proBNP level on day 4, the ICH score, and the APACHE II score were independent prognostic factors of functional outcome and 6-month mortality in ICH patients. A cutoff NT-proBNP level of 999.85 pg/ml predicted an unfavorable functional outcome (with 66.1% sensitivity and 98.7% specificity) and 6-month mortality (with 93.8% sensitivity and 92.0% specificity) in ICH patients. Thus, the NT-proBNP level on day 4 was found to be a powerful prognostic predictor of functional outcome and 6-month mortality in ICH patients, which would be beneficial to guiding the initial management decisions in the setting of ICH.

Electrochemical impedimetric detection of stroke biomarker NT-proBNP using disposable screen-printed gold electrodes

Stroke is the second top leading cause of death globally. It is caused by an abrupt interruption of blood flow to the brain. In that course, brain natriuretic peptide (BNP) and its derivative N-terminal pro b-type natriuretic peptide (NT-proBNP), neurohormones produced mainly by the heart ventricles in response to excessive stretching of cardiomyocytes (heart muscle cells), are proven to be good biomarkers for heart failure diagnosis. Moreover, there is growing clinical interest of the use of NT-proBNP for stroke diagnosis and prognosis because it is significantly associated with cardioembolic stroke and secondary stroke reoccurrence, with sensitivity >90% and specificity >80%. However, in diagnostic settings, there is still a need to address the encountered analytical problems, particularly assay specificity and set up. In this study, a novel approach for NT-proBNP detection is demonstrated using an electrochemical immunoassay method. A label-free impedimetry immunosensor for stroke biomarker was developed using modified disposable screen-printed gold electrodes (SPGE) hosting specific anti-NT-proBNP capture antibody. The performance of our immunosensor was studied in the presence of NT-proBNP in both buffered and mock (porcine) plasma samples. A linear relation between the relative total resistance (ΔRtot) responses and the NT-proBNP concentrations in buffer was observed in a range from 0.1 to 5 ng mL-1 with a correlation coefficient (R2) of 0.94656. Overall, the biosensor has demonstrated the capability to quantitate NT-proBNP and differentiate such concentrations in a low concentration range, especially among 0, 0.1, 0.5, 1, and 3 ng mL-1 in plasma samples within 25 min. This range is valuable not only for classifying cardioembolic stroke (higher or equal to 0.5 ng mL-1), but also predicting the risk of secondary stroke reoccurrence (higher than 0.255 ng mL-1). Our biosensor has the potential to be used as an easy-to-use point-of-care test that is both accurate and affordable.

YiQiFuMai Powder Injection attenuates coronary artery ligation-induced myocardial remodeling and heart failure through modulating MAPKs signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

YiQiFuMai Powder Injection (YQFM), a traditional Chinese medicine prescription re-developed based on Sheng-Mai-San, is a classical and traditional therapeutic for clinical heart failure (HF) and angina. However, its potential mechanism against HF remains unclear.

AIM OF THE STUDY

The present study observes the therapeutic role of YQFM and mechanisms underlying its effects on coronary artery ligation (CAL)-induced myocardial remodeling (MR) and HF.

METHODS

MR and HF were induced by permanent CAL for 2 weeks in ICR mice. Then mice were treated with YQFM (0.13g/kg, 0.26g/kg and 0.53g/kg) once a day until 2 weeks later. Cardiac structure and function were evaluated by echocardiography. Serum lactate dehydrogenase (LDH), creatine kinase (CK) and malondialdehyde (MDA) were measured by biochemical kits and cardiomyocyte morphology was assessed by hematoxylin-eosin (HE) staining. Myocardial hydroxyproline (HYP), serum amino-terminal pro-peptide of pro-collagen type III (PIIINP), and Masson's trichrome staining were employed to evaluate cardiac fibrosis. Circulating level of N-terminal pro-B-type natriuretic peptide (NT-proBNP) was tested by ELISA kit to predict prognosis of CAL-induced HF. Effects of YQFM on the mitogen-activated protein kinases (MAPKs) pathway after CAL operation was evaluated by Western blotting and immunohistochemistry assay.

RESULTS

YQFM (0.53g/kg) improved the left ventricular (LV) function and structure impairment after 2 weeks in CAL mice. YQFM administration also decreased LDH and CK activities, circulating levels of MDA, PIIINP, NT-proBNP, and HYP contents. Moreover, YQFM ameliorated cardiac injury and fibrosis. Furthermore, YQFM (0.53g/kg) inhibited the myocardial phosphorylation of MAPKs in HF mice.

CONCLUSION

Our findings suggest that YQFM attenuates CAL-induced HF via improving cardiac function, attenuating structure damage, oxidative stress, necrosis, collagen deposition, and fibrosis. In addition, YQFM ameliorates cardiac remodeling and HF, partially through inhibiting the MAPKs signaling pathways. These data provide insights and mechanisms into the widely application of YQFM in patients with HF, MI and other ischemic heart diseases.

Investigation of optimum N-terminal probrain natriuretic peptide level in patients on maintained hemodialysis

Background: Serum N-terminal probrain natriuretic peptide (NT-proBNP) level is known to be strongly associated with fluid overload, and serves as a guide for fluid management in patients on hemodialysis (HD). This study aimed at investigating the relationship between NT-proBNP level and blood pressure (BP), ultrafiltration/dry weight ratio as well as hemoglobin, and to explore the optimal cutoff point of NT-proBNP level in Chinese patients on HD.

Methods: A total of 306 patients on maintained HD for stage 5 chronic kidney disease (CKD) were included in this prospective study. Their average ultrafiltration/dry weight ratio and BP before dialysis were recorded. The serum NT-proBNP, hemoglobin, serum calcium, and phosphorus were detected. The cutoff value for NT-proBNP level was calculated using receiver operating characteristic (ROC) analysis.

Results: The high NT-proBNP level was associated with high BP and ultrafiltration/dry weight ratio, and low hemoglobin level. The optimal cutoff point of NT-proBNP level for patients on maintained HD was 5666 pg/mL, with a sensitivity of 78.5%, specificity of 43.9%, and area under the curve (AUC) of 0.703 (<0.001).

Conclusions: NT-proBNP level ≤5666 pg/mL was recommended to achieve the target BP, hemoglobin level, and ultrafiltration/dry weight ratio in patients on maintained HD with an ejection fraction (EF) >50%.

Vector synthesis high-resolution electrocardiography, atrial natriuretic peptide and N-terminal prohormone brain natriuretic peptide for estimation of cardiac load in pregnancy

AIM

We analyzed atrial natriuretic peptide (ANP), N-terminal pro-brain natriuretic natriuretic peptide (NT-proBNP) and vector synthesis high-resolution electrocardiography (ECG), to estimate cardiac load with circulatory dynamic change from pregnancy through the post-partum period.

METHODS

The subjects were singleton pregnant women (n = 19), who were divided into three stages: stage 1, 34-36 weeks of gestation; stage 2, 2-6 post-partum days; and stage 3, 1-3 months after delivery. Vector synthesis high-resolution ECG, ANP and NT-proBNP were analyzed for all subjects.

RESULTS

A pregnant woman with massive uterin liomyoma expressed largest the corrected recover time (RTc) dispersion in I + II of tow Dimensional (2D) color distribution map ANP and NT-proBNP were significantly higher in stage 2 than in stages 1 and 3.

CONCLUSIONS

ANP, NT-proBNP and vector synthesis high-resolution ECG there might be able to evaluate cardiac load of normal pregnancy.

N-terminal fragment of the type-B natriuretic peptide (NT-proBNP) contributes to a simple new frailty score in patients with newly diagnosed multiple myeloma

Multiple myeloma (MM) patient frailty has been delineated primarily by age and ECOG performance score (PS) and recently by the IMWG frailty score based on functional status [Activity of Daily Living (ADL) and Instrumental‐ADL scores], comorbidities [Charlson‐comorbidity‐index (CCI)] and age. It was hypothesized that N‐terminal natriuretic peptide type B (NT‐proBNP) might be both a more convenient measure of frailty and a predictor of overall survival (OS). Three‐hundred and fifty‐one consecutive symptomatic MM patients who were seen at Mayo Clinic within 30 days of diagnosis and who had blood stored were eligible. Data from the first visit was abstracted and used to calculate an ADL, CCI, and measure the NT‐proBNP level. The best cutoff of NT‐proBNP predicting OS was 300 ng/L. Variables predictive for OS were ECOG‐PS, age, CCI, ADL, ISS, revised‐ISS, and NT‐proBNP. On multivariate analysis age ≥70, PS ≥2, and NT‐proBNP ≥300 were independent predictors of survival. Patients were assigned a score of 1 for each of these variables, creating stages I–IV with scores of 0–3 points, respectively. The median OS from diagnosis was not reached, 58, 28, and 18 months (P < 0.0001), respectively. This frailty risk schema was independent of initial therapy and the revised‐ISS. NT‐proBNP is a useful predictor of survival independent of age and PS. It is a widely available biomarker that could be added to the panel of laboratory tests of newly diagnosed MM patients and serve as a simple and objective tool of determining frailty in clinical practice. Am. J. Hematol. 91:1129–1134, 2016. © 2016 Wiley Periodicals, Inc.

The role of N-terminal pro-brain natriuretic peptide in prediction of postoperative atrial fibrillation

AIM

To analyze prognostic value of different factors in postoperative atrial fibrillation prediction.

MATERIAL AND METHODS

Study included 39 patients with coronary artery disease without previous paroxysmal atrial fibrillation. Multiple correlation, logistic regression and ROC-analysis were performed to create predictive model of postoperative atrial fibrillation prognosis. Authors have analyzed most of described in literature preoperative predictors of atrial fibrillation to define the role of different risk factors. Prognostic role of N-terminal pro-brain natriuretic peptide (NT-proBNP) is assessed.

RESULTS

We revealed high informativeness of NT-proBNP to predict postoperative atrial fibrillation after on-pump coronary artery bypass grafting.

Early Detection of Kawasaki Disease in Infants

BACKGROUND AND OBJECTIVES

This study aimed to investigate the clinical characteristics of infantile Kawasaki disease (KD), and to evaluate early diagnostic features of KD in febrile infants.

SUBJECTS AND METHODS

We retrospectively reviewed the medical records of 64 KD patients from January 2010 to October 2014. There was an analysis of the clinical, laboratory data of the infants versus children groups. Furthermore, the clinical and laboratory data of infantile KD patients were compared with 16 infants who were admitted for other acute febrile diseases.

RESULTS

A total of 64 patients with KD were identified; 20 (31.3%) were infants; 44 (68.8%) were >1 year old children. Incomplete KD was much more common in infants (n=13, 65.0%) than in children group (n=14, 31.8%) (p=0.013). The infants were characterized by significantly higher rates of inflammatory changes at the Bacille Calmett-Guérin (BCG) inoculation site (p<0.001), but lower rates of changes in the extremities (p=0.029) and cervical lymphadenopathy (p=0.006). The serum levels of platelet after 1 week (p=0.005), C-reactive protein (p=0.038), and N-terminal pro-brain natriuretic peptide (NT-proBNP) (p=0.026) were all significantly higher in the infants group. Comparing the infants with KD versus the other acute febrile diseases, there were significantly higher serum levels of erythrocyte sedimentation rate (p=0.002), C-reactive protein (p=0.046) and NT-proBNP (p=0.001) for the infants with KD group.

CONCLUSION

BCGitis and higher levels of NT-proBNP can be helpful for early diagnosis of the incomplete KD in infants, and may be a good predictor of KD in acute febrile infants, when combined with other acute phase reactants.

B-type Natriuretic Peptide circulating forms: Analytical and bioactivity issues

B-type Natriuretic Peptide (BNP), A-type and C-type Natriuretic Peptides (ANP and CNP) comprise a family of peptides that retain a common ring structure and conserved amino acid sequences. All are present in the heart, but only BNP and ANP are regarded as primarily cardiac secretory products. BNP and ANP, acting through a guanylyl cyclase receptor, increase sodium and water excretion by the kidney, induce vasodilation, reduce blood pressure, counteract the bioactivity of the renin-angiotensin-aldosterone and sympathetic nervous systems and possess anti-hypertrophic and anti-fibrotic properties. BNP is synthesised in cardiomyocytes first as the precursor peptide preproBNP. Removal of the signal peptide from preproBNP produces proBNP which is cleaved to produce the biologically active carboxy-terminal BNP peptide and the inactive N-terminal fragment, NT-proBNP. BNP, NT-proBNP, proBNP and the C-terminal portion of the BNP signal peptide have been detected in human plasma as well as multiple sub-forms including truncated forms of BNP and NT-proBNP, as well as variable glycosylation of NT-proBNP and proBNP. The origin of these circulating forms, their potential bioactivity and their detection by current analytical methods are presented in this review.

Sensitive immunosensor for N-terminal pro-brain natriuretic peptide based on N-(aminobutyl)-N-(ethylisoluminol)-functionalized gold nanodots/multiwalled carbon nanotube electrochemiluminescence nanointerface

A novel electrochemiluminescence (ECL) immunosensor was developed for the determination of N-terminal pro-brain natriuretic peptide (NT-proBNP) by using N-(aminobutyl)-N-(ethylisoluminol) (ABEI)-functionalized gold nanodots/chitosan/multiwalled carbon nanotubes (ABEI/GNDs/chitosan/COOH-MWCNTs) hybrid as nanointerface. First, ABEI/GNDs/chitosan/COOH-MWCNTs hybrid nanomaterials were grafted onto the surface of ITO electrode via the film-forming property of hybrid nanomaterials. The anti-NT-proBNP antibody was connected to the surface of modified electrode by virtue of amide reaction via glutaraldehyde. The obtained sensing platform showed strong and stable ECL signal. When NT-proBNP was captured by its antibody immobilized on the sensing platform via immunoreaction, the ECL intensity decreased. Direct ECL signal changes were used for the determination of NT-proBNP. The present ECL immunosensor demonstrated a quite wide linear range of 0.01-100 pg/mL. The achieved low detection limit of 3.86 fg/mL was about 3 orders of magnitude lower than that obtained with electrochemistry method reported previously. Because of the simple and fast analysis, high sensitivity and selectivity, and stable and reliable response, the present immunosensor has been successfully applied to quantify NT-proBNP in practical plasma samples. The success of the sensor in this work also confirms that ABEI/GNDs/chitosan/COOH-MWCNTs hybrid is an ideal nanointerface to fabricate a sensing platform. Furthermore, the proposed strategy could be applied in the detection of other clinically important biomarkers.

Brain-type natriuretic peptide levels correlate with pulmonary hypertension and requirement for extracorporeal membrane oxygenation in congenital diaphragmatic hernia

PURPOSE

B-type natriuretic peptide (BNP), an established biomarker of ventricular pressure overload, is used in the assessment of children with pulmonary hypertension (PH). PH is commonly observed in congenital diaphragmatic hernia (CDH). However, the use of BNP levels to guide treatment in this patient population has not been well defined. In this study, we investigate BNP levels in a large cohort of CDH patients treated at a single institution.

METHODS

We retrospectively reviewed charts of all CDH patients enrolled in our pulmonary hypoplasia program from 2004-2013. PH was assessed by echocardiography using defined criteria, and patients were further stratified into the following cohorts: no PH, short-term PH (requiring nitric oxide but no additional vasodilatory therapy), long-term PH (requiring continued vasodilatory therapy post-discharge), and ECMO (requiring ECMO therapy).

RESULTS

A total of 132 patients were studied. BNP levels were significantly increased in patients with PH compared to patients with normal pulmonary pressures (P<0.01). BNP levels were not significantly different between the ST-PH, LT-PH, and ECMO cohorts, but all levels in all three cohorts were significantly increased compared to patients who did not develop PH.

CONCLUSION

Our findings indicate that plasma BNP levels correlate with pulmonary hypertension as well as the requirement for ECMO in CDH patients. Monitoring of serial BNP levels may provide a useful prognostic tool in the management of CDH.

A multimarker approach to diagnose and stratify heart failure

BACKGROUND

We have previously demonstrated that circulating NT-proBNP is truncated at the N and C termini. Aims of this study are three-fold: firstly to determine whether the NT-proBNP levels correlate with NYHA functional classes when measuring with different antibody pairs; secondly to evaluate the diagnostic potential of ProBNP and; thirdly to investigate whether combining NT-proBNP assays with or without ProBNP would lead to better diagnostic accuracies.

METHODS

Plasma samples were collected from healthy controls (n=52) and HF patients (n=46). Customized AlphaLISA® immunoassays were developed and validated to measure the concentrations of proBNP and NT-proBNP (with antibodies targeting 13-45, 13-76, 28-76). The diagnostic performance and predictive value of proBNP and NT-proBNP assays and their combinations were evaluated.

RESULTS

Plasma proBNP assay showed acceptable diagnostic performance. NT-proBNP13-76 assay is useful in diagnosing and stratifying HF patients. The diagnostic performance of NT-proBNP13-76 demonstrated improvement over commercial NT-proBNP tests. The combination of NT-proBNP13-76 with NT-proBNP28-76 assays gave the best diagnostic assay performance.

CONCLUSION

Our results demonstrate that while there is major heterogeneity in circulating NT-proBNP, specific epitopes of the peptides are extraordinarily stable, providing ideal targets for clinically useful diagnostic assays. Future new clinical diagnostic clinical trials should include a multimarker approach rather than using a single marker to diagnose HF.

Associations of N-terminal pro-B-type natriuretic peptide with kidney function decline in persons without clinical heart failure in the Heart and Soul Study

BACKGROUND

Subclinical volume overload in the absence of diagnosed heart failure (HF) may be an underrecognized contributor to kidney function decline in coronary artery disease (CAD) patients. We evaluated associations of circulating N-terminal pro-B-type natriuretic peptide (NT-proBNP), a marker of ventricular stretch, with change in estimated glomerular filtration rate (eGFR).

METHODS

We evaluated 535 patients with stable CAD and no history of HF, who were enrolled in the Heart and Soul Study and followed for 5 years. N-terminal pro-B-type natriuretic peptide was measured at baseline. We evaluated the associations of NT-proBNP with change in kidney function over 5 years: (a) annual percent change in eGFR, (b) rapid kidney function loss (> 3% per year for 5 years), and (c) incident eGFR < 60 mL/min per 1.73 m2. In multivariable models, we adjusted for demographics, comorbid conditions, echocardiographic parameters, medications, and baseline kidney function.

RESULTS

Among 535 participants, median NT-proBNP was 130.6 (interquartile range 61.8-280.9) pg/mL, and median B-type natriuretic peptide (BNP) was 32.5 (14.4-75.9) pg/mL. Individuals with NT-proBNP levels in the highest quartile (> 280.9 pg/mL) had a greater odds of rapid kidney function loss after full adjustment (odds ratio 2.95; 95% CI 1-8.65; P = .0492). Associations with incident eGFR < 60 mL/min per 1.73 m2 were also significant (adjusted odds ratio 4.23; 95% CI 1.05-16.98; P = .0422). Results were similar when analyzed using BNP as the predictor.

CONCLUSIONS

N-terminal pro-B-type natriuretic peptide and BNP are strongly and independently associated with accelerated kidney function loss, even in the absence of clinical HF. These findings suggest that subclinical cardiovascular dysfunction may contribute to elevated kidney disease risk in persons with CAD.

B-Type Natriuretic Peptide Forms within the Heart, Coronary Sinus, and Peripheral Circulation in Humans: Evidence for Degradation before Secretion

BACKGROUND

The B-type natriuretic peptides (BNP and N-terminal pro-BNP) are secreted by the heart and, in the case of BNP, serve to maintain circulatory homeostasis through renal and vascular actions and oppose many effects of the renin-angiotensin system. Recent evidence suggests that in patients with severe heart failure, circulating immunoreactive BNP is made up mainly of metabolites that may have reduced bioactivity. We hypothesized that BNP may be degraded before it even leaves the heart.

METHODS

Peripheral venous plasma plus atrial and ventricular tissue, obtained from explanted hearts at the time of transplantation, were collected from 3 patients with end-stage heart failure. In a separate study, plasma was collected from the coronary sinus and femoral artery of 3 separate patients undergoing cardiac catheterization. Plasma C18 reverse-phase extracts were separated on reverse-phase HPLC, and the collected fractions were subjected to RIAs with highly specific antisera directed to the amino- and carboxy-terminal ends of BNP(1–32).

RESULTS

ProBNP, BNP(1–32), and 2 major BNP metabolites were present in atrial and ventricular tissue, where BNP(1–32) represented 45% and 70% of total processed BNP, respectively. Neither BNP(1–32) nor the 2 metabolites were detected in peripheral venous plasma. Nor was BNP(1–32) detected in matching coronary sinus and femoral artery plasma from the 3 patients undergoing cardiac catheterization.

CONCLUSIONS

BNP(1–32) is partly degraded within the hearts of patients with end-stage heart failure, and even in patients with relatively well-preserved left ventricular systolic function, only BNP metabolites enter the systemic circulation.

ANP and BNP responses to dehydration in the one-humped camel and effects of blocking the renin-angiotensin system

The objectives of this study were to investigate and compare the responses of atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) in the circulation of hydrated, dehydrated, and dehydrated losartan - treated camels; and to document the cardiac storage form of B-type natriuretic peptide in the camel heart. Eighteen male camels were used in the study: control or hydrated camels (n = 6), dehydrated camels (n = 6) and dehydrated losartan-treated camels (n = 6) which were dehydrated and received the angiotensin II (Ang II) AT-1 receptor blocker, losartan, at a dose of 5 mg/kg body weight intravenously for 20 days. Control animals were supplied with feed and water ad-libitum while both dehydrated and dehydrated-losartan treated groups were supplied with feed ad-libitum but no water for 20 days. Compared with time-matched controls, dehydrated camels exhibited a significant decrease in plasma levels of both ANP and BNP. Losartan-treated camels also exhibited a significant decline in ANP and BNP levels across 20 days of dehydration but the changes were not different from those seen with dehydration alone. Size exclusion high performance liquid chromatography of extracts of camel heart indicated that proB-type natriuretic peptide is the storage form of the peptide. We conclude first, that dehydration in the camel induces vigorous decrements in circulating levels of ANP and BNP; second, blockade of the renin-angiotensin system has little or no modulatory effect on the ANP and BNP responses to dehydration; third, proB-type natriuretic peptide is the storage form of this hormone in the heart of the one-humped camel.

Utility of NT-proBNP for identifying LV failure in patients with acute exacerbation of chronic bronchitis

BACKGROUND

NT-proBNP has been widely regarded as a useful tool for diagnosis or exclusion of heart failure (HF) in many settings. However, in patients with acute exacerbation of chronic bronchitis (AECB), its roles have not been well described. The objective of this study was to evaluate the diagnostic performance of NT-proBNP for identifying left ventricular (LV) failure in such patients.

METHODS AND RESULTS

311 AECB patients and 102 stable chronic bronchitis patients with no history of HF were enrolled. Plasma NT-proBNP concentrations were measured using Roche Elecsys. The European Society of Cardiology (ESC) diagnostic principles were adopted to identify HF and the diagnostic performance of NT-proBNP was evaluated by ROC. Our results showed, the median NT-proBNP level in patients with LV failure [4828.4 (2044.4-9203.6) ng/L] was significantly higher than that in those without LV failure [519.2 (179.1-1409.8) ng/L, p<0.001] and stable controls [207.5 (186.5-318.2) ng/L, p<0.001]. LV failure, renal function, atrial fibrillation and systolic pulmonary artery pressure were independent predictors of NT-proBNP levels (all p<0.05). The area under ROC curve (AUC) of NT-proBNP for identifying LV failure was 0.884, significantly superior to clinical judgment alone (AUC 0.835, p = 0.0294). At the optimal cutoff value of 935.0 ng/L, NT-proBNP yielded sensitivity 94.4%, specificity 68.2%, accuracy 74.3% and negative predictive value 97.6%. Adding the results of NT-proBNP to those of clinical judgment improved the diagnostic accuracy for LV failure.

CONCLUSION

As a tool for diagnosis or exclusion of HF, NT-proBNP can help physicians identify LV failure in patients with AECB.

MS-based approaches to unravel the molecular complexity of proprotein-derived biomarkers and support their quantification: the examples of B-type natriuretic peptide and apelin peptides

The specific forms of described protein biomarkers that occur in human blood are not yet fully established. Even though B-type natriuretic peptide (BNP) and N-terminal proBNP are now well known markers of heart failure and other cardiac disorders, several studies yielded highly controversial results reporting various truncated, multimerized or modified forms in human blood. Similar discrepancies were observed for other biomarkers also originating from proproteins, such as the apelin peptides. The drawback of most of these studies is that they used methods with low resolving power, such as immunoassays after HPLC separation. MS-based techniques may be able to avoid such flaws. In this review, we discuss the usefulness of MS-based approaches for the characterization of circulating forms of peptide biomarkers that originate from a given proprotein. Two particular examples are discussed in detail: BNP-related peptides and some more putative biomarkers of heart failure, the apelin peptides.

Assessment of ST-elevation myocardial infarction-related diastolic dysfunction with compensatory rise in left atrial ejection force

BACKGROUND

It is well known that patients with ST-elevation myocardial infarction (STEMI) show both systolic and diastolic left ventricular dysfunction. The aim of this study was to assess post-myocardial infarction diastolic dysfunction using left atrial ejection force (LAEF) in patients treated with primary percutaneous coronary intervention (PCI).

METHODS AND RESULTS

We enrolled 58 patients presenting with STEMI who were treated with primary PCI and 23 healthy subjects as a control group. A detailed transthoracic echocardiogram, including mitral flow velocities, tissue Doppler mitral annular velocities, and left atrial (LA) phasic volumes, was performed in both groups. We also measured the level of B-type natriuretic peptide (BNP). LAEF was calculated using the formula: 0.5 × P × Mitral orifice area × (Peak A velocity)(2) . Correlations between variables were studied using "Pearson and Spearman's rho" test. In the test group, we found that the level of BNP in the plasma, E/E' ratio, and the LA volume measurements were higher than that of the control group, and those differences were statistically significant. LAEF was increased in patients with myocardial infarction (MI); moderately correlated to BNP (r = 0.383 and P = 0.001) and E/E' (r = 0.473 and P = 0.001), and strongly correlated to A-wave velocity (r = 0.731 and P = 0.001). LAEF was also negatively correlated to E/A ratio (r = -0.419 and P = 0.001) and LVEF (r = -0.339 and P = 0.003).

CONCLUSION

Impaired diastolic function in STEMI affects LA and increased LAEF is one of its manifestations. LAEF may also have diagnostic importance in diastolic dysfunction, but these findings should be confirmed by further studies.

Association of cardiac and renal function with extreme N-terminal fragment pro-B-type natriuretic peptide levels in elderly patients

Background

The data are inconsistent regarding whether extreme N-terminal fragment pro-B-type natriuretic peptide (NT pro-BNP) levels are associated with impaired renal function. Furthermore, the relationship between extreme NT pro-BNP levels and cardiac and renal function in elderly patients has not been reported. The aim of the present study was to examine a hypothesis that extreme NT pro-BNP levels may be associated with impaired cardiac and renal function in elderly patients.

Methods

We retrospectively analyzed the data of demographic, clinical, and echocardiographic features on 152 consecutive elderly patients aged more than 80 years old (average age, 83.65 ± 3.58 years) with NT pro-BNP levels ≥ 3000 pg/ml. The participants were divided into two categories according to their NT pro-BNP levels: (1) 3000–10000 pg/mL and (2) >10000 pg /mL.

Results

The number of patients with impaired renal function (P = 0.019) and the mortality (P < 0.001) in the period of inpatient was higher in the group with NT pro-BNP > 10000 pg /mL. The levels of serum creatinine and creatine kinase MB (CK-MB) in the group of NT pro-BNP > 10000 pg / mL were higher than those in the group of NT pro-BNP = 3000-10000 pg/mL (P = 0.001 and P = 0.023, respectively). Furthermore, no significant difference in the distribution by NYHA class in different NT pro-BNP levels was observed. Multiple linear regression analyses demonstrated that with NT pro-BNP levels as the dependent variable, NT pro-BNP levels were positively correlated with CK-MB (β = 0.182, P = 0.024) and creatinine levels (β = 0.281, P = 0.001). The area under the receiver-operating characteristic (ROC) curve of NT pro-BNP levels and clinical diagnosis of impaired renal function was 0.596 and reached significant difference (95%CI:0.503-0.688, P = 0.044).

Conclusion

These data suggest that the extreme elevation of NT pro-BNP levels (≥3000 pg/ml) is mainly determined by impaired renal function in elderly patients above 80 years. Extreme NT pro-BNP levels may be useful for assessing the severity of impaired renal function.

Changes in cardiac biomarkers during doxorubicin treatment of pediatric patients with high-risk acute lymphoblastic leukemia: associations with long-term echocardiographic outcomes

PURPOSE

Doxorubicin causes cardiac injury and cardiomyopathy in children with acute lymphoblastic leukemia (ALL). Measuring biomarkers during therapy might help individualize treatment by immediately identifying cardiac injury and cardiomyopathy.

PATIENTS AND METHODS

Children with high-risk ALL were randomly assigned to receive doxorubicin alone (n = 100; 75 analyzed) or doxorubicin with dexrazoxane (n = 105; 81 analyzed). Echocardiograms and serial serum measurements of cardiac troponin T (cTnT; cardiac injury biomarker), N-terminal pro-brain natriuretic peptide (NT-proBNP; cardiomyopathy biomarker), and high-sensitivity C-reactive protein (hsCRP; inflammatory biomarker) were obtained before, during, and after treatment.

RESULTS

cTnT levels were increased in 12% of children in the doxorubicin group and in 13% of the doxorubicin-dexrazoxane group before treatment but in 47% and 13%, respectively, after treatment (P = .005). NT-proBNP levels were increased in 89% of children in the doxorubicin group and in 92% of children in the doxorubicin-dexrazoxane group before treatment but in only 48% and 20%, respectively, after treatment (P = .07). The percentage of children with increased hsCRP levels did not differ between groups at any time. In the first 90 days of treatment, detectable increases in cTnT were associated with abnormally reduced left ventricular (LV) mass and LV end-diastolic posterior wall thickness 4 years later (P < .01); increases in NT-proBNP were related to an abnormal LV thickness-to-dimension ratio, suggesting LV remodeling, 4 years later (P = .01). Increases in hsCRP were not associated with any echocardiographic variables.

CONCLUSION

cTnT and NT-proBNP may hold promise as biomarkers of cardiotoxicity in children with high-risk ALL. Definitive validation studies are required to fully establish their range of clinical utility.

Diagnosing destabilized heart failure in the emergency setting: current and future biomarker tests

Acute or destabilized heart failure (DHF) is characterized by new or worsening signs and symptoms of heart failure leading to admission to an emergency department. Biomarkers may support the diagnosis, the prognosis and the management of DHF patients. The aim of this review article is to discuss and evaluate the clinical usefulness of both recognized and potential new biomarker tests for use in heart failure.

B-type natriuretic peptide: from posttranslational processing to clinical measurement

BACKGROUND

Plasma cardiac natriuretic peptides and peptide fragments from their molecular precursors are markers of heart disease. Clinical studies have defined the current diagnostic utility of these markers, whereas biochemical elucidation of peptide structure and posttranslational processing has revealed new plasma peptide forms of potential clinical use.

CONTENT

Natriuretic propeptide structures undergo variable degrees of endo- and exoproteolytic cleavages as well as amino acid modifications, which leave the plasma phase of the peptides highly heterogeneous and dependent on cardiac pathophysiology and capacity. An ongoing characterization of the molecular heterogeneity may not only help us to appreciate the biosynthetic capacity of the endocrine heart but may also lead to the discovery of new and more disease-specific targets for future molecular diagnosis.

SUMMARY

Peptides derived from pro-atrial natriuretic peptide and pro-B-type natriuretic peptide are useful plasma markers in heart failure. New data have defined cardiac myocytes as competent endocrine cells in posttranslational processing and cellular secretion.