The effects of super-flux (high performance) dialyzer on plasma glycosylated pro-B-type natriuretic peptide (proBNP) and glycosylated N-Terminal proBNP in end-stage renal disease patients on dialysis

Kinetics of atrial and brain natriuretic peptides during hemodialysis are regulated in association with different cardiac functional changes

The blood levels of atrial and brain natriuretic peptides (ANP and BNP) are both increased markedly in hemodialysis patients, but the kinetics of the two are not always parallel. The present study investigated the association of changes in ANP and BNP levels before and after dialysis with changes in cardiac function in hemodialysis patients. A total of 57 patients (mean age 64 years, 47 males and 10 females) on maintenance hemodialysis with sinus rhythm were enrolled. Blood samples were taken at the beginning and end of dialysis, and plasma levels of ANP and BNP were measured. Changes in cardiac function during dialysis were examined by echocardiography performed just before and after dialysis. Both plasma ANP and BNP concentrations decreased significantly after hemodialysis, but the rate of decrease in BNP [mean ± SD, 555 ± 503 to 519 ± 477 pg/mL (- 6.4%), P = 0.011] was much smaller than that in ANP [233 ± 123 to 132 ± 83 pg/mL (- 43.4%), P < 0.001]. As for the relation to the changes in echocardiographic parameters before and after dialysis, the decrease in inferior vena cava diameter had a close correlation with the decrease in ANP (r = 0.528, P < 0.001), but not BNP. In contrast, the decrease in left ventricular end-diastolic volume index was correlated only with the decrease in BNP (r = 0.297, P = 0.035). The peak velocity ratio of early diastolic to atrial filling decreased with preload reduction by dialysis, and its decrease was more strongly correlated with the decrease in BNP (r = 0.407, P = 0.002) than that in ANP (r = 0.273, P = 0.040). These results demonstrated that in hemodialysis patients, the decrease in plasma ANP by a single dialysis was essentially caused by blood volume reduction, while BNP decrease was mainly induced by the reduction of left ventricular overload. Our findings indicate that the kinetics of both peptides during dialysis are regulated by different cardiac and hemodynamic factors.

Natriuretic peptides in human heart: Novel insight into their molecular forms, functions, and diagnostic use

Among the three natriuretic peptides, atrial/A-type natriuretic peptide (ANP) and brain/B-type natriuretic peptide (BNP) are primarily produced by, and secreted from, heart tissue. They maintain cardiovascular homeostasis by binding to natriuretic peptide receptor-A. Since plasma ANP and BNP concentrations, as well as expression, are elevated in response to increased body fluid volume and pressure load on the heart wall, these peptides are widely utilized as diagnostic biomarkers for evaluating heart failure. Regardless of their high utility, differences in their molecular forms between healthy and diseased subjects and how these relate to pathophysiology have not well been examined. Recent studies have shown that the circulating molecular forms of ANP and BNP are not uniform; bioactive α-ANP is the major ANP form, whereas the weakly active proBNP is the major BNP form. The relative ratios of the different molecular forms are altered under different pathophysiological conditions. These facts indicate that detailed measurements of each form may provide useful information on the pathophysiological state of heart tissue. Here, we revisit the relationship between the molecular forms of, and pathophysiological alterations in, human ANP and BNP and discuss the possible utility of the measurement of each of the molecular forms. The third peptide, C-type natriuretic peptide, activates natriuretic peptide receptor-B, but little is known about its production and function in the heart because of its extremely low levels. However, through recent studies, its role in the heart is gradually becoming clear. Here, we summarize its molecular forms, assay systems, and functions in the heart.

Translational science: Newly emerging science in biology and medicine - Lessons from translational research on the natriuretic peptide family and leptin

Translation is the process of turning observations in the laboratory, clinic, and community into interventions that improve the health of individuals and the public, ranging from diagnostics and therapeutics to medical procedures and behavioral changes. Translational research is defined as the effort to traverse a particular step of the translation process for a particular target or disease. Translational science is a newly emerging science, distinct from basic and clinical sciences in biology and medicine, and is a field of investigation focused on understanding the scientific and operational principles underlying each step of the translational process. Advances in translational science will increase the efficacy and safety of translational research in all diagnostic and therapeutic areas. This report examines translational research on novel hormones, the natriuretic peptide family and leptin, which have achieved clinical applications or for which studies are still ongoing, and also emphasizes the lessons that translational science has learned from more than 30 years' experience in translational research.

Cutting Edge of Brain Natriuretic Peptide (BNP) Research - The Diversity of BNP Immunoreactivity and Its Clinical Relevance

Brain (or B-type) natriuretic peptide (BNP) is a cardiac hormone produced in the heart and an established biochemical marker for heart failure (HF) because the level in plasma increases in proportion to disease severity. Recently, the diversity of BNP molecular forms in the peripheral circulation, which includes mature BNP (BNP_1-32) and its metabolites (BNP_3-32, BNP_4-32, and BNP_5-32), was demonstrated. Moreover, studies showed that unprocessed BNP prohormone (proBNP) is also secreted from the heart, and its secretion is increased in patients with HF. Interestingly, BNP_1-32, its metabolites, and proBNP are all detected as immunoreactive BNP by the currently available BNP assay system. Current N-terminal proBNP (NT-proBNP) assay systems also can react to both NT-proBNP and proBNP. In addition, the N-terminal region of proBNP and NT-proBNP are often O-glycosylated, which may result in underestimation of total NT-proBNP level, which includes both glycosylated and non-glycosylated NT-proBNP, by the NT-proBNP assay system. More recently, we have shown that miR30-GALNT-dependent O-glycosylation in the N-terminal region of proBNP affects the processing of proBNP and contributes to its secretion from the heart. The level of proBNP relative to BNP (proBNP/BNP ratio) in the coronary sinus is higher in patients with more severe HF. The proBNP/BNP ratio and the deglycosylated NT-proBNP level may be new and clinically useful biomarkers of HF.

Prediction of perioperative cardiac events through preoperative NT-pro-BNP and cTnI after emergent non-cardiac surgery in elderly patients

Objectives

Clinical risk stratification has an important function in preoperative evaluation of patients at risk for cardiac events prior to non-cardiac surgery. The aim of this study was to determine whether the combined measurement of pre-operative N-terminal pro-brain natriuretic peptide (NT-pro-BNP) and cardiac troponin I (cTnI) could provide useful prognostic information about postoperative major adverse cardiac events (MACE) within 30 days in patients aged over 60 years undergoing emergent non-cardiac surgery.

Methods

The study group comprised 2519 patients aged over 60 years that were undergoing emergent non-cardiac surgery between December 2007 and December 2013. NT-pro-BNP and cTnI were measured during hospital admission. The patients were monitored for MACE (cardiac death, non-fatal myocardial infarction, or cardiac arrest) during the 30-day postoperative follow-up period.

Results

MACE occurred in 251 patients (10.0%). Preoperative NT-pro-BNP and cTNI level were significantly higher in the individuals that experienced MACE than in those who did not (P < 0.001). The confounding factors of age, sex, co-morbidities and preoperative medications were adjusted in a multivariate logistic regression analysis. This analysis showed that preoperative NT-proBNP level > 917 pg/mL (OR 4.81, 95% CI 3.446–6.722, P < 0.001) and cTnI ≥ 0.07 ng/mL (OR 8.74, 95% CI 5.881–12.987, P < 0.001) remained significantly and independently associated with MACE after the adjustment of the confounding factors. Kaplan-Meier event-free survival curves demonstrated that patients with preoperative simultaneous NT-proBNP level > 917 pg/mL and cTnT ≥0.07 ng/mL had worse event-free survival than individual assessments of either biomarker.

Conclusion

Preoperative plasma NT-proBNP and cTnI are both independently associated with an increased risk of MACE in elderly patients after emergent non-cardiac surgery. The combination of these biomarkers provides better prognostic information than using either biomarker separately.

Gender-related alterations in plasma adrenomedullin level and its correlation with body weight gain

Plasma levels of adrenomedullin (AM), a bioactive peptide produced in adipose tissue, have been shown to be higher in obese patients than in non-obese patients, but little is known about gender differences in plasma AM levels. The aims of this study were to clarify gender-related alterations in plasma AM levels and to examine the body weight (BW) gain-plasma AM relationship in the general population. We measured plasma AM levels of 346 local residents (62.0±8.9 years, mean±s.d.) in the Kiyotake area, Japan, who underwent a regular health check-up, by a specific fluorescence immunoassay. Plasma AM levels in the female residents were lower than that in the males, and multiple regression analysis revealed a possible gender difference in plasma AM. The AM levels were significantly correlated with BMI or waist circumference in women, but such a relationship was not seen in men. When the subjects were divided into two groups by results of a questionnaire about BW gain of 10 kg or more since the age of 20 years, the plasma AM level of women with BW gain ≧10 kg was significantly higher than that in those without BW gain, although no difference was noted between the men with and without BW gain. In conclusion, possible gender differences were noted in the plasma AM levels and in the BW gain-plasma AM relationship in the general population. The plasma AM levels in the female residents without BW gain seem partly attributable to the lower AM of women.

cGMP: transition from bench to bedside: a report of the 6th International Conference on cGMP Generators, Effectors and Therapeutic Implications

Essential physiological homeostatic processes such as vascular tone, fluid balance, cardiorenal function, and sensory processes are regulated by the second messenger cyclic guanosine 3', 5'-monophosphate (cGMP). Dysregulation of cGMP-dependent pathways plays an important role in cardiovascular diseases such as hypertension, pulmonary hypertension, heart failure, or erectile dysfunction. Thus, the cGMP pathway consisting of the cGMP-generating guanylyl cyclases, protein kinases, and phosphodiesterases (PDE) has evolved to an important drug target and is the focus of a wide variety of research fields ranging from unraveling mechanisms on the molecular level to understanding the regulation of physiological and pathophysiological processes by cGMP. Based on the results from basic and preclinical research, therapeutic drugs have been developed which modulate the cGMP pathway and are investigated in clinical trials. Riociguat, a nitric oxide (NO)-independent soluble guanylyl cyclase stimulator; recombinant B-type natriuretic peptide (BNP); or recombinant atrial natriuretic peptide (ANP) and PDE5 inhibitors are cGMP-modulating drugs that are already available for the treatment of pulmonary hypertension, acute heart failure, and erectile dysfunction, respectively. The latest results from basic to clinical research on cGMP were presented on the 6th International Conference on cGMP in Erfurt, Germany, and are summarized in this article.