Natriuretic Peptides: Physiologic and Analytic Considerations

Effects of long-term dehydration and quick rehydration on the camel kidney: pathological changes and modulation of the expression of solute carrier proteins and aquaporins

BACKGROUND

Recurrent dehydration causes chronic kidney disease in humans and animal models. The dromedary camel kidney has remarkable capacity to preserve water and solute during long-term dehydration. In this study, we investigated the effects of dehydration and subsequent rehydration in the camel's kidney histology/ultrastructure and changes in aquaporin/solute carrier proteins along with gene expression.

RESULTS

In light microscopy, dehydration induced few degenerative and necrotic changes in cells of the cortical tubules with unapparent or little effect on medullary cells. The ultrastructural changes encountered in the cortex were infrequent during dehydration and included nuclear chromatin condensation, cytoplasmic vacuolization, mitochondrial swelling, endoplasmic reticulum/ lysosomal degeneration and sometimes cell death. Some mRNA gene expressions involved in cell stability were upregulated by dehydration. Lesions in endothelial capillaries, glomerular membranes and podocyte tertiary processes in dehydrated camels indicated disruption of glomerular filtration barrier which were mostly corrected by rehydration. The changes in proximal tubules brush borders after dehydration, were accompanied by down regulation of ATP1A1 mRNA involved in Na + /K + pump that were corrected by rehydration. The increased serum Na, osmolality and vasopressin were paralleled by modulation in expression level for corresponding SLC genes with net Na retention in cortex which were corrected by rehydration. Medullary collecting ducts and interstitial connective tissue were mostly unaffected during dehydration. CKD, a chronic nephropathy induced by recurrent dehydration in human and animal models and characterized by interstitial fibrosis and glomerular sclerosis, were not observed in the dehydrated/rehydrated camel kidneys. The initiating factors, endogenous fructose, AVP/AVPR2 and uric acid levels were not much affected. TGF-β1 protein and TGF-β1gene expression showed no changes by dehydration in cortex/medulla to mediate fibrosis. KCNN4 gene expression level was hardly detected in the dehydrated camel's kidney; to encode for Ca +  + -gated KCa3.1 channel for Ca +  + influx to instigate TGF-β1. Modulation of AQP 1, 2, 3, 4, 9 and SLC protein and/or mRNAs expression levels during dehydration/rehydration was reported.

CONCLUSIONS

Long-term dehydration induces reversible or irreversible ultrastructural changes in kidney cortex with minor effects in medulla. Modulation of AQP channels, SLC and their mRNAs expression levels during dehydration/rehydration have a role in water conservation. Cortex and medulla respond differently to dehydration/rehydration.

Rheumatoid arthritis increases the risk of heart failure-current evidence from genome-wide association studies

Background

Numerous studies have demonstrated that rheumatoid arthritis (RA) is related to increased incidence of heart failure (HF), but the underlying association remains unclear. In this study, the potential association of RA and HF was clarified using Mendelian randomization analysis.

Methods

Genetic tools for RA, HF, autoimmune disease (AD), and NT-proBNP were acquired from genome-wide studies without population overlap. The inverse variance weighting method was employed for MR analysis. Meanwhile, the results were verified in terms of reliability by using a series of analyses and assessments.

Results

According to MR analysis, its genetic susceptibility to RA may lead to increased risk of heart failure (OR=1.02226, 95%CI [1.005495-1.039304], P=0.009067), but RA was not associated with NT-proBNP. In addition, RA was a type of AD, and the genetic susceptibility of AD had a close relation to increased risk of heart failure (OR=1.045157, 95%CI [1.010249-1.081272], P=0.010825), while AD was not associated with NT-proBNP. In addition, the MR Steiger test revealed that RA was causal for HF and not the opposite (P = 0.000).

Conclusion

The causal role of RA in HF was explored to recognize the underlying mechanisms of RA and facilitate comprehensive HF evaluation and treatment of RA.

Gender-Related Differences in Heart Failure Biomarkers

Important differences in comorbidities and clinical characteristics exist between women and men with heart failure (HF). In particular, differences in the kinetics of biological circulating biomarkers—a critical component of cardiovascular care—are highly relevant. Most circulating HF biomarkers are assessed daily by clinicians without taking sex into account, despite the multiple gender-related differences observed in plasma concentrations. Even in health, compared to men, women tend to exhibit higher levels of natriuretic peptides and galectin-3 and lower levels of cardiac troponins and the cardiac stress marker, soluble ST2. Many biological factors can provide a reliable explanation for these differences, like body composition, fat distribution, or menopausal status. Notwithstanding, these sex-specific differences in biomarker levels do not reflect different pathobiological mechanisms in HF between women and men, and they do not necessarily imply a need to use different diagnostic cut-off levels in clinical practice. To date, the sex-specific prognostic value of HF biomarkers for risk stratification is an unresolved issue that future research must elucidate. This review outlines current evidence regarding gender-related differences in circulating biomarkers widely used in HF, the pathophysiological mechanisms underlying these differences, and their clinical relevance.

A new algorithm for suspected stroke patient management with NT-proBNP POCT platform in the emergency department: A new algorithm for suspected stroke patient

Introduction:

Stroke is a leading cause of mortality and morbidity in China. Of the different subtypes of ischemic stroke, cardioembolic stroke is of particular importance because it is potentially preventable. This study aimed to evaluate the usefulness of measuring N-terminal pro-brain natriuretic peptide in the emergency department in early recognition of patients with cardioembolic stroke.

Methods:

This was a multicenter prospective cohort study conducted from 1 June 2015 to 30 June 2016 in four emergency departments. Adult patients with acute ischemic stroke were recruited. Plasma N-terminal pro-brain natriuretic peptide was measured in the emergency department. Discharge diagnosis was determined by neurologists according to the Trial of ORG 10172 in Acute Stroke Treatment criteria. The diagnostic performance of N-terminal pro-brain natriuretic peptide was assessed by measuring the sensitivity, specificity, receiver operating characteristic curve, and the area under curve.

Results:

In all, 258 patients were analyzed. Of them, 17.9% were diagnosed with cardioembolic stroke. The optimal cut-off concentration, sensitivity, specificity, and the area under the curve of the plasma N-terminal pro-brain natriuretic peptide concentration suitable to distinguish cardioembolic stroke from other subtypes of stroke were 501.2 pg/mL, 82.6%, 80.2%, and 0.87 (95% confidence interval: 0.83–0.92), respectively.

Conclusion:

Emergency physicians should strongly consider cardioembolic stroke in patients presented with acute ischemic stroke with an N-terminal pro-brain natriuretic peptide level over 501.2 pg/mL. However, it must be considered in context with clinical assessment and judgment before making treatment decisions.

Prognostic and diagnostic significance of copeptin in acute exacerbation of chronic obstructive pulmonary disease and acute heart failure: data from the ACE 2 study

BACKGROUND

Copeptin is a novel biomarker that predicts mortality in lower respiratory tract infections and heart failure (HF), but the diagnostic value of copeptin in acute dyspnea and the prognostic significance of copeptin in acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is not clear.

METHOD

We determined copeptin and NT-proBNP concentrations at hospital admission in 314 patients with acute dyspnea who were categorized by diagnosis. Survival was registered after a median follow-up of 816 days, and the prognostic and diagnostic properties of copeptin and NT-proBNP were analyzed in acute HF (n = 143) and AECOPD (n = 84) separately.

RESULTS

The median concentration of copeptin at admission was lower in AECOPD compared to acute HF (8.8 [5.2-19.7] vs. 22.2 [10.2-47.9]) pmol/L, p < 0.001), but NT-proBNP discriminated acute HF from non-HF related dyspnea more accurately than copeptin (ROC-AUC 0.85 [0.81-0.89] vs. 0.71 [0.66-0.77], p < 0.0001). Adjusted for basic risk factors, increased copeptin concentrations predicted mortality in AECOPD (HR per log (ln) unit 1.72 [95% CI 1.21-2.45], p = 0.003) and acute HF (1.61 [1.25-2.09], p < 0.001), whereas NT-proBNP concentrations predicted mortality only in acute HF (1.62 [1.27-2.06], p < 0.001). On top of a basic model copeptin reclassified a significant proportion of patients into a more accurate risk strata in AECOPD (NRI 0.60 [0.19-1.02], p = 0.004) and acute HF (0.39 [0.06-0.71], p = 0.020).

CONCLUSION

Copeptin is a strong prognostic marker in both AECOPD and acute HF, while NT-proBNP concentrations predict mortality only in patients with acute HF. NT-proBNP levels are superior to copeptin levels to diagnose acute HF in patients with acute dyspnea.

Differential expression of B-type natriuretic peptide between left and right ventricles, with particular regard to sudden cardiac death

The aim of the present study was to investigate the differential expression of B-type natriuretic peptide (BNP) between the left and right ventricle (RV) in sudden cardiac death (SCD). A total of 26 forensic autopsy cases of sudden death (survival time <30 min, postmortem interval <48 h or frozen within 6 h following death) in the present institute were examined. The cases consisted of acute ischemic heart disease (AIHD, n=15) with/without apparent myocardial necrosis as a sign of infarction (acute myocardial infarction, n=6; ischemic heart disease, IHD, n=9), and arrhythmogenic right ventricular cardiomyopathy (ARVC/D, n=5), in addition to traffic accidents and high falls without any pre existing heart disease as control (C, total n=6). BNP was investigated in all cases by the colloidal gold method, hematoxylin-eosin staining, immunohistochemistry (IHC) and the molecular pathological method. The IHC results demonstrated that a positive BNP immunostaining was detected in all groups; however, there was no difference between different causes of death. Pericardial N-terminal (NT)-proBNP concentration was significantly increased in deaths resulting from AIHD and ARVC/D compared with control group. The relative quantification of BNP mRNA demonstrated that relative expression levels of BNP mRNA were significantly increased in the left ventricle (LV) in the AIHD group, and in the RV of the ARVC/D group. The relative quantification difference and ratio of BNP mRNA between LV and RV demonstrated a significantly greater value in the AIHD group compared with control group. BNP mRNA in myocardium and NT-proBNP concentration in pericardial fluid were elevated in SCD patients, and left ventricular dysfunction predominated in AIHD patients, whereas right ventricular dysfunction predominated in ARVC/D patients. The results of the present study suggest the possible use of molecular pathology of BNP for the determination of terminal cardiac function in SCD and analysis of its fatal mechanism in forensic practice.

Continuous administration of recombinant human B-type natriuretic peptide can improve heart and renal function in patients after cardiopulmonary bypass surgery

BACKGROUND

Any cardiac surgery under cardiopulmonary bypass (CPB) will induce ischemia-reperfusion injury and systematic inflammatory response, which may lead to exacerbation. Conventional therapy strategy is to use inotropes, diuretics and vasodilator drugs, yet, the therapeutic effects of which need to be improved. Recombinant human B-type natriuretic peptide (rhBNP) has been shown to be efficacious in the treatment of acute decompensated heart failure and acute myocardial infarction. However, the effects of rhBNP on patients carried out CPB surgery is unknown.

METHODS

We retrospect 357 patients carried out CPB surgery between Jan 1st 2014 and Dec 31st 2015 of our department. And according the use of rhBNP, these patients were divided into two groups: rhBNP group and control group. Patients in rhBNP group were received continuous intravenous rhBNP (0.0075-0.01 µg/kg/min) in 6 hours after CPB surgery, for a period of 72 h. Hemodynamic parameters were measured immediately after CPB surgery, and then at 2, 4, 8, 12 and 24 h after surgery. Blood samples were obtained immediately after surgery and thereafter once a day at 6:00 AM within the first 3 days after surgery. The daily urine volume as well as the time of tracheal intubation, ICU stay and chest drainage were also recorded.

RESULTS

The baseline characteristics and heart functions were well balanced between two groups, and no patient died in the surgery. It showed significant differences in time-dependent changes in both groups of MAP (P<0.0001, within groups), MPAP (P<0.0001, within groups), PAWP (P<0.0001, within groups), CI (P<0.0001, within groups), SVRI (P<0.0001, within groups), serum BNP (P<0.0001, within groups), CK-MB (P<0.0001, within groups), troponin (P<0.0001, within groups) and creatinine (P<0.0001, within groups). It also showed significant differences in time-dependent changes between the two groups of MAP (P=0.04, between groups), PAWP (P=0.04, between groups), serum troponin (P<0.0001, between groups), serum creatinine (P<0.0001, between groups) and urine volume (P<0.0001, between groups). Interestingly, our results showed that patients in rhBNP group tended to wean off the respirator half a day later than those in control group (P=0.05), while no significant difference showed in both the length of chest drainage time and intensive care unit stay between the two groups.

CONCLUSIONS

The administration of rhBNP can improve heart and renal function in patients underwent CPB surgery as well as accelerating the recovery from myocardial injury. But the prognosis of the patients who were administrated rhBNP did not improve in our study.

Brain natriuretic peptide: Much more than a biomarker

Brain natriuretic peptide (BNP) modulates several biological processes by activating the natriuretic peptide receptor A (NPR-A). Atria and ventricles secrete BNP. BNP increases natriuresis, diuresis and vasodilatation, thus resulting in a decreased cardiac workload. BNP and NT-proBNP, which is the biologically inactive N-terminal portion of its pro-hormone, are fast and sensitive biomarkers for diagnosing heart failure. The plasma concentrations of both BNP and NT-proBNP also correlate with left ventricular function in patients with acute exacerbation of COPD, even without history of heart failure. Several studies have been conducted in vitro and in vivo, both in animals and in humans, in order to assess the potential role of the NPR-A activation as a novel therapeutic approach for treating obstructive pulmonary disorders. Unfortunately, these studies have yielded conflicting results. Nevertheless, further recent specific studies, performed in ex vivo models of asthma and COPD, have confirmed the bronchorelaxant effect of BNP and its protective role against bronchial hyperresponsiveness in human airways. These studies have also clarified the intimate mechanism of action of BNP, represented by an autocrine loop elicited by the activation of NPR-A, localized on bronchial epithelium, and the relaxant response of the surrounding ASM, which does not expresses NPR-A. This review explores the teleological activities and paradoxical effects of BNP with regard to chronic obstructive respiratory disorders, and provides an excursus on the main scientific findings that explain why BNP should be considered much more than a biomarker.

N-Terminal Pro-Brain Natriuretic Peptide (NT-proBNP) and Risk of Hypertension in the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Brain natriuretic peptide (BNP) is released by the heart in response to ventricular and auricular wall stress. Release of BNP is traditionally considered part of the body's protective mechanism against pressure overload by inducing vasodilatation and diuresis. More recent evidence demonstrates that BNP also promotes vessel wall stress and preliminary studies suggest that chronic increased levels may increase risk of hypertension. This study aimed to evaluate the prospective association of N-terminal BNP (NT-proBNP), a cleavage product of BNP, with risk of hypertension in the Atherosclerosis Risk in Communities cohort study.

METHODS

We conducted a prospective analysis of 3,798 middle-aged participants in the ARIC study without hypertension at baseline (1996-1998). Using Cox proportional hazards models, we characterized the association between NT-proBNP at baseline and newly diagnosed hypertension for a maximum of 14 years of follow-up (median = 9 years).

RESULTS

We observed 2,113 new hypertension cases over the follow-up period. Higher baseline NT-proBNP was independently associated with an increased risk of hypertension. Adjusted hazard ratios for incident hypertension in the highest quartile compared to the lowest quartile of NT-proBNP at baseline was 1.24 (95% CI: 1.08-1.42). Each log-unit increase in NT-proBNP was associated with an 8% increased risk of hypertension (95% CI: 1.03-1.13).

CONCLUSIONS

Persons with elevated NT-proBNP, even with normal blood pressure at baseline, were at increased risk of developing hypertension. Our results suggest that elevated circulating BNP might contribute to the development of hypertension in previously normotensive individuals.

NT-proBNP on Cobas h 232 in point-of-care testing: Performance in the primary health care versus in the hospital laboratory

BACKGROUND

NT-proBNP may be useful for ruling out heart failure in primary health care. In this study we examined the analytical quality of NT-proBNP in primary health care on the Cobas h 232 point-of-care instrument compared with measurements performed in a hospital laboratory.

MATERIALS AND METHODS

Blood samples requested for NT-proBNP were collected in primary health care (n = 95) and in a hospital laboratory (n = 107). NT-proBNP was measured on-site on Cobas h 232 instruments both in primary health care centres and at the hospital laboratory and all samples were also analyzed with a comparison method at the hospital. Precision, trueness, accuracy, and lot-variation were determined at different concentration levels and evaluated according to acceptance criteria. Furthermore user-friendliness was assessed by questionnaires.

RESULTS

For Cobas h 232 repeatability CV was 8.5-10.7% in the hospital setting and 5.3-10.0% in the primary health care and within the analytical quality specifications, but higher than with the comparison method (< 4%). NT-proBNP results obtained in primary health care were significantly higher than by the hospital comparison method (bias ranged from 14.3-23.7%), whereas there was no significant bias when Cobas h 232 was used in the hospital setting (bias ranged from - 4.9 to 7.0%). User-friendliness of Cobas h 232 was overall acceptable.

CONCLUSION

Cobas h 232 point-of-care instrument for measurement of NT-proBNP performed satisfactorily with regard to precision, user-friendliness, and lot-variation. A decrease in NT-proBNP levels observed in samples transported to a central laboratory needs further attention and investigation.

B-type natriuretic peptides for the prediction of cardiovascular events in patients with stable coronary heart disease: the Heart and Soul Study

Background

Brain‐type natriuretic peptide (BNP) and the amino‐terminal fragment of its prohormone (NT‐proBNP) are known predictors of cardiovascular outcomes in patients with coronary heart disease; however, the relative prognostic value of these 2 biomarkers for secondary events remains unclear.

Methods and Results

In 983 participants with stable coronary heart disease, we evaluated the association of BNP and NT‐proBNP with time to hospitalization for heart failure, nonfatal myocardial infarction, stroke or transient ischemic attack, cardiovascular death, and combined major adverse cardiovascular events (MACE). During an average follow‐up of 6.5±3.3 years, both BNP and NT‐proBNP were associated with increased risk of MACE in a multivariable‐adjusted model (hazard ratio per standard deviation of log BNP: 1.58; 95% CI: 1.32 to 1.89; hazard ratio per standard deviation of log NT‐proBNP: 1.84; 95% CI: 1.52 to 2.24). When added to traditional risk factors, NT‐proBNP predicted MACE better than BNP (C statistic: 0.76 versus 0.72, P<0.001). Similarly, the addition of NT‐proBNP resulted in a greater net reclassification improvement for predicting MACE than the addition of BNP (65% for NT‐proBNP, 56% for BNP).

Conclusions

Both BNP and NT‐proBNP were significant predictors of MACE in stable coronary heart disease; however, NT‐proBNP was superior to BNP for net risk reclassification for MACE.

Clinical and molecular genetics of the phosphodiesterases (PDEs)

Cyclic nucleotide phosphodiesterases (PDEs) are enzymes that have the unique function of terminating cyclic nucleotide signaling by catalyzing the hydrolysis of cAMP and GMP. They are critical regulators of the intracellular concentrations of cAMP and cGMP as well as of their signaling pathways and downstream biological effects. PDEs have been exploited pharmacologically for more than half a century, and some of the most successful drugs worldwide today affect PDE function. Recently, mutations in PDE genes have been identified as causative of certain human genetic diseases; even more recently, functional variants of PDE genes have been suggested to play a potential role in predisposition to tumors and/or cancer, especially in cAMP-sensitive tissues. Mouse models have been developed that point to wide developmental effects of PDEs from heart function to reproduction, to tumors, and beyond. This review brings together knowledge from a variety of disciplines (biochemistry and pharmacology, oncology, endocrinology, and reproductive sciences) with emphasis on recent research on PDEs, how PDEs affect cAMP and cGMP signaling in health and disease, and what pharmacological exploitations of PDEs may be useful in modulating cyclic nucleotide signaling in a way that prevents or treats certain human diseases.

Noninvasive ventilation in the event of acute respiratory failure in patients with idiopathic pulmonary fibrosis

BACKGROUND

Some patients with idiopathic pulmonary fibrosis (IPF) develop severe acute respiratory failure (ARF) requiring admission to an intensive care unit (ICU) and ventilatory support. A limited number of observational studies have reported that noninvasive ventilation (NIV) can be an effective treatment to support breathing and to prevent use of invasive mechanical ventilation in these patients. This study aimed to retrospectively investigate the clinical status and outcomes in IPF patients receiving NIV for ARF and to identify those clinical and laboratory characteristics, which could be considered risk factors for its failure.

METHODS

This is a retrospective analysis of short-term outcomes in 18 IPF patients being administered NIV for ARF. This study was conducted in a 4-bed respiratory ICU (RICU) in a university hospital. Eighteen IPF patients who were administered NIV between January 1, 2005, and April 30, 2013, were included. The outcome measures are the need for endotracheal intubation despite NIV treatment and mortality rate during their RICU stay. The length of the patients' stay in the RICU and their survival rate following RICU admission were also evaluated.

RESULTS

Noninvasive ventilation was successful in 8 patients and unsuccessful in 10 who required endotracheal intubation. All the patients in the NIV failure group died within 20.2±15.3 days of intubation. The patients in the NIV success group spent fewer days in the RICU (11.6±4.5 vs 24.6±13.7; P=.0146). The median survival time was significantly shorter for the patients in the NIV failure with respect to the success group (18.0 [95% confidence interval {CI}, 9.0-25.0] vs 90.0 [95% CI, 65.0-305.0] days; P<.0001); the survival rate at 90 days was, likewise, lower in the NIV failure group (0% vs 34%±19.5%). At admission, the patients in the failure group had significantly higher respiratory rate values (36.9±7.8 vs 30.5±3.3 breaths/min; P=.036), plasma N-terminal fragment of the prohormone of B-type natriuretic peptide (NT-proBNP) levels (4528.8±4012.8 vs 634.6±808.0 pg/mL; P=.023) and serum C-reactive protein values (72.0±50.0 vs 20.7±24.0 μg/mL; P=.0289) with respect to those in the success group. Noninvasive ventilation failure was correlated to the plasma NT-proBNP levels at RICU admission (P=.0326) with an odds ratio of 12.2 (95% CI, 1.2 to infinity) in the patients with abnormally high values (>900 pg/mL).

CONCLUSIONS

The outcome of IPF patients who were administered NIV was quite poor. The use of NIV was, nevertheless, found to be associated with clinical benefits in selected IPF patients, preventing the need for intubation and reducing the rate of complications/death. Elevated plasma NT-proBNP levels at the time of ICU admission is a simple clinical marker for poor NIV outcome.

Comparative effects of recombinant human brain natriuretic peptide and dobutamine on acute decompensated heart failure patients with different blood BNP levels

Background

Recombinant human B-type natriuretic peptide (rhBNP) has been indicated for the treatment of acute decompensated heart failure (ADHF). However, the therapeutic efficacy of intravenous rhBNP is not always satisfactory in patients with extremely high blood BNP levels. In this study, we evaluated the effects of rhBNP on patients with different BNP levels.

Methods

One hundred and five patients with ADHF whose left ventricular ejection fraction (LVEF) was <40%, were assigned to a high BNP group (BNP ≤ 3000 pg/mL) or an extra-high BNP group (BNP > 3000 pg/mL) , depending on their admission plasma BNP levels. Each group was then subdivided into rhBNP or dobutamine subgroups according to intravenous administration with either rhBNP or dobutamine for 24-72h. In the high BNP group, 58 patients were randomized to subgroup rhBNP (n = 28) and subgroup dobutamine (n = 30). In the extra-high BNP group, 47 patients were randomized to subgroup rhBNP (n = 24) and subgroup dobutamine (n = 23). The effects of rhBNP and dobutamine on patients in the high and extra-high BNP groups were compared.

Results

In the high BNP group, rhBNP was more efficient than dobutamine at improving NYHA classification (P < 0.05), decreasing plasma BNP levels (P < 0.05), increasing LVEF (P < 0.05), and reducing hospital length of stay (P < 0.05). However, rhBNP displayed no superior therapeutic efficacy to dobutamine in the extra-high BNP group. Adverse cardiovascular events in patients treated with rhBNP were similar to adverse events in patients treated with dobutamine in both the high and extra-high BNP groups.

Conclusions

rhBNP was more efficient than dobutamine at improving heart function in patients with ADHF when plasma BNP was ≤3000 pg/mL. However, rhBNP treatment showed no advantages over dobutamine when plasma BNP reached extremely high levels (>3000 pg/mL).

Trial registration

ClinicalTrials.gov Identifier: NCT01837849.

TNF-α regulates natriuretic peptides and aquaporins in human bronchial epithelial cells BEAS-2B

Postoperative-fluid retention is a severe complication frequently reported in patients undergoing major surgical procedures. The complex network of molecules involved in such a severe surgery-induced condition remains poorly understood. Inflammation has been proposed among the various causes of fluid retention. Since TNF-α is one of the main proinflammatory cytokine initially released after major surgery, it is reasonable to assume its involvement in fluid overload. Here, we showed that TNF-α selectively regulates key molecules involved in fluids balance, such as natriuretic peptides (NPs) and aquaporins, in human bronchial epithelial cells BEAS-2B. In particular, we found that TNF-α induced a decrease of arial natriuretic peptide, natriuretic peptide receptor-1, aquaporin-1 and aquaporin-5 and an increase of brain natriuretic peptide with a different involvement of nuclear factor-κB and mitogen-activated protein kinases signaling pathway activation. Moreover, the observed changes in NPs expression, demonstrate inflammation as an additional cause of brain natriuretic peptide elevation, adding an important piece of information in the novel area of study regarding NPs and inflammation. Finally, we suggest that inflammation is one of the mechanisms of Aquaporin-1 and aquaporin-5 expression regulation. Therefore, in this exploratory study, we speculate that TNF-α might be involved in postoperative-fluid retention related to major surgery.

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.

High-sensitivity cardiac troponin T levels are increased in stable COPD

Objective

To assess the distribution of high-sensitivity cardiac troponin T (hs-cTnT) concentrations in stable chronic obstructive pulmonary disease (COPD), and whether hs-cTnT is associated with pulmonary function.

Design

Prospectively designed, cross-sectional study.

Setting

Outpatient clinic of Norwegian teaching hospital and community-based setting.

Participants

Sample of 101 stable COPD patients from the hospital's outpatient clinic and 120 individuals derived from a random general population sample.

Main outcomes

Ratio of hs-cTnT in stable COPD patients compared with references from the general population. Change in ratio of hs-cTnT per unit increase of relevant covariables.

Results

The crude geometric means of circulating hs-cTnT in the cases and the references were 7.75 and 3.01 ng/l, respectively (p <0.001); that is, a relative ratio of 2.57 (95% CI 2.05 to 3.23). After adjustment for relevant confounders, this ratio was moderately attenuated to 1.65 (1.31–2.08). In the total study cohort, as well as among stable COPD patients, we found a significant positive association between hs-cTnT and interleukin-6 concentrations (p <0.001) and the presence of pathologic Q waves (p=0.023). Among stable COPD patients, one quartile increase in forced expiratory volume 1 was associated with a 39% decrease in hs-cTnT and patient category (Global Initiative of Obstructive Lung Disease  classification 2011) was positively associated with hs-cTnT (p trend <0.001) after multivariate adjustment.

Conclusions

Stable COPD is independently associated with higher hs-cTnT compared with randomly drawn subjects from the general population. In patients with stable COPD, higher hs-cTnT seems to be associated with immune activation and the severity of the disease.

NT-proBNP independently predicts long term mortality after acute exacerbation of COPD - a prospective cohort study

Background

Cardiovascular disease is prevalent and frequently unrecognized in patients with chronic obstructive pulmonary disease (COPD). NT-proBNP is an established risk factor in patients with heart failure. NT-proBNP may also be released from the right ventricle. Thus serum NT-proBNP may be elevated during acute exacerbations of COPD (AECOPD). The prognostic value of NT-proBNP in patients hospitalized with AECOPD is sparsely studied. Our objective was to test the hypothesis that NT-proBNP independently predicts long term mortality following AECOPD.

Methods

A prospective cohort study of 99 patients with 217 admissions with AECOPD. Clinical, electrocardiographic, radiological and biochemical data were collected at index and repeat admissions and analyzed in an extended survival analysis with time-dependent covariables.

Results

Median follow-up time was 1.9 years, and 57 patients died during follow-up. NT-proBNP tertile limits were 264.4 and 909 pg/mL, and NT-proBNP in tertiles 1 through 3 was associated with mortality rates of 8.6, 35 and 62 per 100 patient-years, respectively (age-adjusted log-rank p<0.0001). After adjustment for age, gender, peripheral edema, cephalization and cTnT in a multivariable survival model, the corresponding hazard ratios for dying were 2.4 (0.95-6.0) and 3.2 (1.3-8.1) (with 95% confidence intervals in parentheses, p-value for trend 0.013).

Conclusions

NT-proBNP is a strong and independent determinant of mortality after AECOPD.

Plasma BNP, a useful marker of fluid overload in hospitalized hemodialysis patients

Hospitalization for intercurrent illness frequently disrupts the nutritional status of hemodialysis (HD) patients and jeopardizes the dry weight prescription. We report in this study the evolution of brain natriuretic peptide (BNP), blood pressure and body weight in hospitalized patients and the relationship between BNP plasma level and nutritional and inflammation parameters. We have studied 42 patients requiring hospitalization (F/M: 18/24; 72.5 ± 12.5 years old; 19/42 with diabetes). The plasma BNP levels at baseline, during hospitalization (BNP-Hosp), and in the recovery phase were compared. Predialysis and postdialysis blood pressure and postdialysis body weight were recorded and compared. BNP-Hosp increased significantly when compared with BNP levels at baseline, from 421 ± 647.2 pg/mL to 1584 ± 1584.4 pg/mL (P < 0.0001). Brain natriuretic peptide decreased from 1223 ± 1342.1 pg/mL during hospitalization to 616 ± 892.1 pg/mL after discharge (P = 0.005). The BNP-Hosp was positively correlated with C-reactive protein (P = 0.003) and negatively correlated with serum prealbumin (P = 0.0001) and albumin (P = 0.0001). The postdialysis body weight prescription decreased from 71.0 ± 15.7 kg at baseline to 70.5 ± 15.4 kg during hospitalization and to 67.8 ± 14.4 kg 4 months after discharge (P = 0.0032). Our study displays clearly the significant changes of plasma BNP levels occurring during intercurrent events. Fluid overload triggered by inflammation-associated catabolism and the lag time for dry weight adjustment is the cause of this finding. Hence, plasma BNP level may be used as a marker of fluid overload in patients with intercurrent events and may allow efficient dry weight adjustment. We cannot rule out an effect of inflammation on BNP synthesis.

Epithelium integrity is crucial for the relaxant activity of brain natriuretic peptide in human isolated bronchi

BACKGROUND AND PURPOSE Brain natriuretic peptide (BNP) plays an important role in several biological functions, including bronchial relaxation. Here, we have investigated the role of BNP and its cognate receptors in human bronchial tone. EXPERIMENTAL APPROACH Effects of BNP on responses to carbachol and histamine were evaluated in non-sensitized, passively sensitized, epithelium-intact or denuded isolated bronchi and in the presence of methoctramine, N(ω) -nitro-L-arginine methyl ester (L-NAME) and aminoguanidine. Natriuretic peptide receptors (NPRs) were investigated by immunohistochemistry, RT-PCR and real-time PCR. Release of NO and acetylcholine from bronchial tissues and cultured BEAS-2B bronchial epithelial cells was also investigated. KEY RESULTS BNP reduced contractions mediated by carbachol and histamine, with decreased E(max) (carbachol: 22.7 ± 4.7%; histamine: 59.3 ± 1.8%) and increased EC(50) (carbachol: control 3.33 ± 0.88 µM, BNP 100 ± 52.9 µM; histamine: control 16.7 ± 1.7 µM, BNP 90 ± 30.6 µM); BNP was ineffective in epithelium-denuded bronchi. Among NPRs, only atrial NPR (NPR1) transcripts were detected in bronchial tissue. Bronchial NPR1 immunoreactivity was detected in epithelium and inflammatory cells but faint or absent in airway smooth muscle cells. NPR1 transcripts in bronchi increased after incubation with BNP, but not after sensitization. Methoctramine and quinine abolished BNP-induced relaxant activity. The latter was associated with increased bronchial mRNA for NO synthase and NO release, inhibited by L-NAME and aminoguanidine. In vitro, BNP increased acetylcholine release from bronchial epithelial cells, whereas NO release was unchanged. CONCLUSIONS AND IMPLICATIONS Epithelial cells mediate the BNP-induced relaxant activity in human isolated bronchi.

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.

Predicting mortality and hospital admission in patients with COPD: significance of NT pro-BNP, clinical and echocardiographic assessment

AIMS

To quantify the ability of N-terminal pro-brain natriuretic peptide (NT pro-BNP) to predict mortality and hospitalization in patients with chronic obstructive airways disease (COPD).

METHODS

Prospective single-centre observational study of 140 consecutive patients aged at least 18 years with COPD between 27 March 2004 and 28 February 2008 (median follow-up 3.9 years).

RESULTS

Sixty-five (46%) men, 26 (19%) O2 therapy, 115 (82%) smokers, 38 (27%) patients receiving diuretics, 15 (11%) left-ventricular ejection fraction less than 45%. Median [interquartile range (IQR)] NT pro-BNP concentration 16.2 (25.4) pmol/l. NT pro-BNP was higher in those with a dilated left atrium (P<0.001), aortic stenosis (P=0.02), left-ventricular systolic dysfunction (P=0.027), right ventricular impairment (P=0.011), atrial fibrillation (P<0.001), patients receiving diuretics (P=0.010) and angiotensin-converting enzyme (ACE) inhibitors (P=0.006). One-year mortality and hospitalization rates were 2.9 and 25.4%. The median (IQR) time to hospitalization and length of first hospital stay: 383.5 (605) and 4.0 (7.0) days. NT pro-BNP was an excellent discriminator of right-ventricular impairment (C statistic=0.90) and predicted survival (highest quartile versus lowest quartile relative risk=3.02, P=0.001), but not hospital admission. After adjustment this association was not significant.

CONCLUSION

NT pro-BNP predicts survival, but not hospital admission in patients with COPD. The ability of NT pro-BNP to independently predict death or hospitalization is superseded by the presence of a dilated left atrium, aortic stenosis and left-ventricular systolic dysfunction.

Utilization of B-type natriuretic peptide and NT-proBNP in the diagnosis of pleural effusions due to heart failure

PURPOSE OF REVIEW

The natriuretic peptides B-type natriuretic peptide (BNP) and NT-proBNP have been incorporated into the existing clinical guidelines for the diagnostic evaluation of heart failure. Recent evidence has provided important information regarding the relative value of each of these peptides to differentiate between pleural effusions caused by heart failure and those attributable to other causes.

RECENT FINDINGS

In a meta-analysis of 10 studies, which included 1120 patients, pleural fluid levels of NT-proBNP had a pooled sensitivity and specificity of 94%, a positive likelihood ratio of 15.2, and a negative likelihood ratio of 0.06 in identifying heart failure-related effusions. Because pleural fluid and serum natriuretic peptide levels are closely correlated and display similar discriminatory properties, blood tests alone are sufficient. More than 85% of heart failure patients whose pleural fluids meet exudative criteria exhibit high pleural NT-proBNP concentrations. The diagnostic performance of pleural fluid BNP has been reported to be inferior to that of NT-proBNP.

SUMMARY

NT-proBNP is an established biomarker of heart failure-associated effusions and the most effective tool for recognizing cardiac effusions that are misclassified as exudates by Light's criteria. If clinicians choose pleural fluid specimens for natriuretic peptide testing, the lower diagnostic accuracy of BNP makes it a poor substitute for NT-proBNP measurements.

Evaluation of N-terminal pro-B-type natriuretic peptide as a diagnostic marker of various stages of cardiomyopathy in Doberman Pinschers

OBJECTIVE

To evaluate the diagnostic value of plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentrations in Doberman Pinschers in various stages of dilated cardiomyopathy (DCM).

ANIMALS

328 Doberman Pinschers.

PROCEDURES

Staging of DCM was determined via analysis of results of physical examinations, 24-hour ambulatory ECG (Holter) recordings, and echocardiographic evaluations. Plasma samples for NT-proBNP assays were obtained at each examination. Concentrations of NT-proBNP were measured in 337 samples obtained from 196 healthy Doberman Pinschers (control dogs) and in 195 samples obtained from 132 Doberman Pinschers in various stages of DCM. These included dogs that had ventricular premature contractions (VPCs; 79 samples), echocardiographic changes (23 samples), or both (51 samples); 16 samples were from dogs with overt DCM, and 26 were from dogs that were considered normal during initial examination but developed DCM within 1.5 years after this assessment. Receiver operating characteristic curves were analyzed to determine sensitivity and specificity of NT-proBNP concentrations for detection of DCM.

RESULTS

NT-proBNP concentrations in dogs that had or developed DCM were significantly higher than those of control dogs. Sensitivity and specificity of NT-proBNP concentrations (cutoff value, > 400 pmol/L) to detect all stages of DCM were 81.1 % and 75.0%, respectively; sensitivity was 90.0% and specificity was 75.0% to predict echocardiographic changes. Specificity to detect echocardiographic changes was 90.4% at a cutoff value of 550 pmol/L.

CONCLUSIONS AND CLINICAL RELEVANCE

Plasma concentrations of NT-proBNP were increased in dogs with DCM and in apparently healthy dogs that developed DCM within 1.5 years after samples were obtained, compared with concentrations in control dogs.

Measurement of NT-proBNP with LOCI technology in heart failure patients

OBJECTIVES

The aim of our study was to determine NT-proBNP concentrations in heart failure (HF) patients with a luminescent oxygen channeling immunoassay (LOCI).

DESIGN AND METHODS

Seventy HF patients were enrolled. NT-proBNP levels were measured with LOCI method and compared to a reference NT-proBNP assay.

RESULTS

LOCI NT-proBNP levels were significantly correlated with the reference NT-proBNP assay and were related to HF severity.

CONCLUSIONS

LOCI assay demonstrates performances close to the comparative assay for NT-proBNP testing and allows a significant reduction of the time of analysis.

Narrative review: the management of acute decompensated heart failure

Acute decompensated heart failure (ADHF) is the most common reason for hospitalization in Western nations. The prognosis of patients admitted to hospital with ADHF is poor, with up to 64% being readmitted within the first 90 days after discharge and with a 1-year mortality approximating 20%. Epidemiological studies suggest that the majority of patients hospitalized with ADHF receive treatment that is inadequate and which is not based on scientific evidence. Furthermore, emerging data suggest that the "conventional" therapeutic interventions for ADHF including morphine, high-dose diuretics, and inotropic agents may be harmful. The goal of this review is to provide evidence-based recommendations for the diagnosis and management of ADHF.

Use of B-type natriuretic peptide as a screening tool for left ventricular diastolic dysfunction in rheumatoid arthritis patients without clinical cardiovascular disease

OBJECTIVE

Patients with rheumatoid arthritis (RA) are at an increased risk for heart failure and left ventricular diastolic dysfunction (LVDD). B-type natriuretic peptide (BNP) may be useful to screen for LVDD in the general population. We compared the effectiveness of BNP as a screening tool for LVDD in RA and non-RA subjects without cardiovascular disease (CVD).

METHODS

Study subjects were recruited from population-based samples with and without RA, excluding subjects with CVD. LVDD was assessed by 2-dimensional and Doppler echocardiography and categorized as none, mild, moderate/severe, or indeterminate. Linear regression and proportional odds models evaluated the association between LVDD and BNP, adjusting for age, sex, and body mass index.

RESULTS

Among 231 RA and 1,730 non-RA subjects without CVD, BNP was significantly higher in subjects with moderate/severe LVDD compared to those with no or mild LVDD (P = 0.02 for RA and P < 0.001 for non-RA subjects). More RA subjects had elevated BNP than non-RA subjects (16% versus 9%; P < 0.001). Positive predictive value (25% in RA and 18% in non-RA subjects) and sensitivity (40% in RA and 26% in non-RA subjects) were similarly low in both cohorts, but specificity was significantly lower in RA than in non-RA subjects (89% versus 94%; P = 0.02).

CONCLUSION

While RA subjects were more likely to have elevated BNP, few RA patients with elevated BNP actually have LVDD. Also, normal BNP levels are less likely to rule out LVDD in RA than in non-RA subjects. Therefore, BNP may be less effective for screening in RA subjects compared to the general population.

Prognosis of vascular surgery patients using a quantitative assessment of troponin T release: is the crystal ball still clear?

BACKGROUND

Cardiac troponin T (cTnT) assays with increased sensitivity might increase the number of positive tests. Using the area under the curve (AUC) with serial sampling of cTnT an exact quantification of the myocardial damage size can be made. We compared the prognosis of vascular surgery patients with integrated cTnT-AUC values to continuous and standard 12-lead electrocardiography (ECG) changes.

METHODS

513 Patients were monitored. cTnT sampling was performed on postoperative days 1, 3, 7, 30 and/or at discharge or whenever clinically indicated. If cTnT release occurred, daily measurements of cTnT were performed, until baseline was achieved. CTnT-AUC was quantified and divided in tertiles. All-cause mortality and cardiovascular events (cardiac death and myocardial infarction) were noted during follow-up.

RESULTS

81/513 (16%) Patients had cTnT release. After adjustment for gender, cardiac risk factors, and site and type of surgery, those in the highest cTnT-AUC tertile were associated with a significantly worse cardiovascular outcome and long-term mortality (HR 20.2; 95% CI 10.2-40.0 and HR 4.0; 95% CI 2.0-7.8 respectively). Receiver operator analysis showed that the best cut-off value for cTnT-AUC was <0.01 days*ng m for predicting long-term cardiovascular events and all-cause mortality.

CONCLUSION

In vascular surgery patients quantitative assessment of cTnT strongly predicts long-term outcome.

Atrial natriuretic peptide and oxidative stress

Atrial natriuretic peptide (ANP) is a hormone, produced mainly by cardiomyocytes, with a major role in cardiovascular homeostatic mechanisms such as natriuresis and vasodilation, which serve to regulate blood pressure. However, ANP also acts as an autocrine/paracrine factor on other targets such as kidney, lung, thymus, liver and the immune system. ANP participates in the regulation of cell growth and proliferation, and evidence is accumulating that these effects are associated with the generation of reactive oxygen species (ROS). In vascular cells and cardiomyocytes ANP stimulates the antioxidant defense, but in other systems such as hepatoblastoma and macrophages ANP may produce either antioxidant or prooxidant effects, depending on experimental conditions and cell context. At present very little is known on the relationship between ANP and ROS production in the normal homeostatic processes or during the development of cardiovascular diseases and cancer. Our current knowledge of the role of ANP in signaling pathways leading to the generation of intracellular messengers such as diacylglycerol (DAG), and guanosine 3'-5'-cyclic monophosphate has been examined in order to clarify the mechanisms by which the hormone may counteract or contribute to the potentially dangerous effects of free radicals.

Risk factors and outcome of new-onset cardiac arrhythmias in vascular surgery patients

BACKGROUND

The pathophysiology of new-onset cardiac arrhythmias is complex and may bring about severe cardiovascular complications. The relevance of perioperative arrhythmias during vascular surgery has not been investigated. The aim of this study was to assess risk factors and prognosis of new-onset arrhythmias during vascular surgery.

METHODS

A total of 513 vascular surgery patients, without a history of arrhythmias, were included. Cardiac risk factors, inflammatory status, and left ventricular function (LVF; N-terminal pro-B-type natriuretic peptide and echocardiography) were assessed. Continuous electrocardiography (ECG) recordings for 72 hours were used to identify ischemia and new-onset arrhythmias: atrial fibrillation, sustained ventricular tachycardia, supraventricular tachycardia, and ventricular fibrillation. Logistic regression analysis was applied to identify preoperative risk factors for arrhythmias. Cox regression analysis assessed the impact of arrhythmias on cardiovascular event-free survival during 1.7 years.

RESULTS

New-onset arrhythmias occurred in 55 (11%) of 513 patients: atrial fibrillation, ventricular tachycardia, supraventricular tachycardia, and ventricular fibrillation occurred in 4%, 7%, 1%, and 0.2%, respectively. Continuous ECG showed myocardial ischemia and arrhythmias in 17 (3%) of 513 patients. Arrhythmia was preceded by ischemia in 10 of 55 cases. Increased age and reduced LVF were risk factors for the development of arrhythmias. Multivariate analysis showed that perioperative arrhythmias were associated with long-term cardiovascular events, irrespective of the presence of perioperative ischemia (hazard ratio 2.2, 95% CI 1.3-3.8, P = .004).

CONCLUSION

New-onset perioperative arrhythmias are common after vascular surgery. The elderly and patients with reduced LVF show arrhythmias. Perioperative continuous ECG monitoring helps to identify this high-risk group at increased risk of cardiovascular events and death.

Atrial natriuretic peptides and urodilatin modulate proximal tubule Na(+)-ATPase activity through activation of the NPR-A/cGMP/PKG pathway

The signaling pathway mediating modulation of Na(+)-ATPase of proximal tubule cells by atrial natriuretic peptides (ANP) and urodilatin through receptors located in luminal and basolateral membranes (BLM) is investigated. In isolated BLM, 10(-11)M ANP or 10(-11)M urodilatin inhibited the enzyme activity (50%). Immunodetection revealed the presence of NPR-A in BLM and LLC-PK1 cells. Both compounds increased protein kinase G (PKG) activity (80%) and this effect did not occur with 10(-6)M LY83583, a specific inhibitor of guanylyl cyclase. The inhibitory effect of these peptides on Na(+)-ATPase activity did not occur after addition of 10(-6)M KT5823, a specific inhibitor of PKG. LLC-PK1 cells were used to investigate if ANP and urodilatin change the activity of sodium pumps by luminal receptor interaction. ANP and urodilatin inhibited Na(+)-ATPase activity (50%), with maximal effect at 10(-10)M, similar to 10(-7)M db-cGMP, and did not occur with 10(-7)M LY83583, a guanylyl cyclase inhibitor. ANP and urodilatin specifically inhibit Na(+)-ATPase activity by activation of the cGMP/PKG pathway through NPR-A located in luminal membrane and BLM, increasing understanding of the mechanism of natriuretic peptides on renal sodium excretion, with proximal tubule Na(+)-ATPase one possible target.