Adrenomedullin and nitrite levels in children with Bartter syndrome

A Review of Adrenomedullin in Pediatric Patients: A Useful Biomarker

Adrenomedullin has several properties. It acts as a potent vasodilator, has natriuretic effects, and reduces endothelial permeability. It also plays a role in initiating the early hyperdynamic phase of sepsis. Since its discovery, many articles have been published studying the uses and benefits of this biomarker. The aim of this review is to determine the usefulness of adrenomedullin in pediatric patients. Relevant studies covering adrenomedullin in pediatrics (<18 years) and published up until August 2021 were identified through a search of MEDLINE, PubMed, Embase, Web of Science, Scopus, and Cochrane. Seventy studies were included in the present review, most of them with a low level of evidence (IV to VI). Research on adrenomedullin has primarily been related to infection and the cardiovascular field. The performance of adrenomedullin to quantify infection in children seems satisfactory, especially in sepsis. In congenital heart disease, this biomarker seems to be a useful indicator before, during, and after cardiopulmonary bypass. Adrenomedullin seems to be useful in the pediatric population for a large variety of pathologies, especially regarding infection and cardiovascular conditions. However, it should be used in combination with other biomarkers and clinical or analytical variables, rather than as a single tool.

Combined evaluation of plasma B-type natriuretic peptide and urinary liver-type fatty acid-binding protein/creatinine ratio is related to worsening renal function in patients undergoing elective percutaneous coronary intervention

BACKGROUND

There are few reports on the significance for the combined evaluation of blood humoral factors and urinary biomarkers in terms of worsening renal function (WRF) after coronary angiography (CAG)/percutaneous coronary arterial intervention (PCI).

METHOD AND RESULTS

Urinary liver type-fatty acid-binding protein (L-FABP), neutrophil gelatinase associated lipocalin (NGAL), and adrenomedullin (AM) were measured less than 24 h before and 3 h, 6 h, 1 day, and 2 days after CAG/PCI. WRF was defined as a > 20% decrease in the estimated GFR. WRF occurred in seven of 100 patients and the increase in L-FABP/creatinine (Cr) at 1 day after CAG/PCI was significantly higher in the WRF group than in the non-WRF group. Plasma B-type natriuretic peptide (BNP) before CAG/PCI and L-FABP/Cr at 1 day after CAG/PCI were independent predictors for WRF. The areas under the receiver-operating characteristic curves were as follows: 0.760 for BNP before CAG/PCI, 0.731 for L-FABP/Cr at 1 day after CAG/PCI, and 0.892 for BNP and L-FABP/Cr. Urinary AM levels after PCI/CAG were negatively correlated only to serum potassium levels. Gene expressions of AM and AM-receptor were detectable in renal tubule epithelial cells. AM increased intracellular second messenger levels in a dose-dependent manner.

CONCLUSIONS

Our results suggest that combined evaluation of plasma BNP and urinary L-FABP/Cr is useful as a predictor of renal dysfunction in CAG/PCI patients.

Serum vascular endothelial growth factor, transforming growth factor β1, and nitric oxide levels in patients with psoriasis vulgaris: their correlation to disease severity

BACKGROUND

Vascular endothelial growth factor (VEGF), transforming growth factor β1 (TGF-β1), and nitric oxide (NO) have been reported to be contributory factors to the pathogenesis of psoriasis vulgaris. In the current study, we aimed to investigate the association between the levels of VEGF, TGF-β1, and NO and psoriasis severity (as expressed by psoriasis area severity index, PASI).

METHODS

Fifty-eight patients with psoriasis vulgaris and twenty-two controls were included in the study. The serum levels of VEGF and TGF-β1 were estimated by ELISA technique. The serum levels of NO were determined by colorimetric method.

RESULTS

The serum levels of VEGF, TGF-β1, and NO were significantly higher in patients than controls. Moreover, the serum levels of the studied biochemical variables in patients with severe disease activity were significantly higher than mild cases. The duration of disease showed significant positive correlations with each VEGF (r = 0.35, P < 0.01) and TGF-β1 (r = 0.41, P < 0.05). In addition, the PASI score was significantly positively correlated with VEGF (r = 0.65, P < 0.001), TGF-β1 (r = 0.31, P < 0.05), and NO (r = 0.51, P < 0.001).

CONCLUSION

These findings suggest an association between psoriasis disease severity and serum levels of VEGF, TGF-β1, and NO, which can be recognized as markers of the psoriasis severity. The modulation of their production may represent a therapeutic potential strategy for psoriasis.

Plasma adrenomedullin levels in children with asthma: any relation with atopic dermatitis?

BACKGROUND

Asthma is a chronic, inflammatory disease of the airway, and adrenomedullin (ADM) may have some effects against bronchoconstriction. However, the role(s) of ADM in asthmatic children have not been evaluated yet. The aims of this study were to determine if there are any changes in plasma ADM levels during acute asthma attack, and to search for any association between allergen sensitivity and ADM level in asthmatic children.

METHODS

Twenty-seven children with acute asthma attack, ranging in age from 5 to 15 years were investigated and compared with 20 controls. Plasma ADM levels (ng/mL) were measured by ELISA method.

RESULTS

No significant difference was found in ADM levels between the controls and patients in either the acute attack or remission period. Plasma ADM levels were significantly higher in the acute attack (p=0.043) compared to the remission period in patients who were considered as having a "severe attack" according to GINA (Global Initiative for Asthma) classification. There were statistically significant correlations between the patients' AlaTOP and Food Panel 7 levels and plasma ADM levels in the acute attack period (p=0.010, p=0.001, respectively). The ADM levels in patients with a history of atopic dermatitis were significantly higher in the acute attack period compared to those without a history of atopic dermatitis (p=0.007).

CONCLUSION

We speculate that ADM may have a role in children with atopic dermatitis, and may also have a role in the immuno-inflammatory process of asthma.

Adrenomedullin Function in Vascular Endothelial Cells: Insights from Genetic Mouse Models

Adrenomedullin is a highly conserved peptide implicated in a variety of physiological processes ranging from pregnancy and embryonic development to tumor progression. This review highlights past and present studies that have contributed to our current appreciation of the important roles adrenomedullin plays in both normal and disease conditions. We provide a particular emphasis on the functions of adrenomedullin in vascular endothelial cells and how experimental approaches in genetic mouse models have helped to drive the field forward.

Nitric oxide and malondialdehyde levels in plasma and tissue of psoriasis patients

BACKGROUND

The pathogenesis of psoriasis has not been known exactly yet. Recently, it has been suggested that increased reactive oxygen species (ROS) such as nitric oxide (NO) and malondialdehyde (MDA) may play a part in the pathogenesis of various skin diseases, including psoriasis.

OBJECTIVES

In this study, we aimed to investigate the role of ROS in the pathogenesis of psoriasis.

METHODS

A convenience sample of 23 patients with psoriasis and 23 healthy subjects consented to participate in the study. Plasma NO and MDA levels were measured in all participants. Psoriasis area and severity index (PASI) and tissue levels of MDA on lesional and non-lesional skin regions of psoriasis patients were measured. In addition, the correlation between age, gender with plasma NO, plasma MDA and tissue MDA was assessed.

RESULTS

Plasma levels of NO and MDA in psoriasis patients (135.8 μmol/L, 4.33 μmol/L, respectively) were statistically significantly higher than those in controls (33.6 μmol/L, 2.03 μmol/L, respectively). Tissue levels of MDA in lesional tissues (49.18 nmol/gr) were significantly higher than those in non-lesional tissues (28.41 nmol/gr). A significant correlation was not found between the PASI and levels of NO and MDA. In addition, a significant negative correlation was found between the plasma NO levels and age.

CONCLUSION

NO and MDA levels are elevated in psoriasis patients, which may indicate that oxidative stress plays an important role in the aetiopathogenesis of psoriasis.

Kidney is in trouble with mediators

The kidneys receive 20-25 % of cardiac output and play a main role in the control of cardiovascular homeostasis. It is an endocrine organ that regulates and produces many substances, scavenger particles and immune complexes. Cytokines, growth factors, reactive oxygen metabolites, bioactive lipids, proteases, vasoactive substances such as nitric oxide (NO), adrenomedullin (AM), urotensin-II (U-II), have been released in several diseases, and kidney is one of mostly affected organs in body. Some of these mediators act in a paracrine fashion while some act in autocrine. They play important roles in modulating the cardiovascular responses, renal hemodynamics, and probably in mediating the clinical and laboratory manifestations of several renal diseases. These mediators are like "a double edged sword". While small amounts of them mediate many physiological events, little excess may cause the damage to the healthy cells. Many investigators have searched the role(s) of mediators in several diseases. However, the findings are mostly like the model of "chicken and egg", and indistinguishable as to whether they are the causes of, or results of the diseases. We will discuss mainly the possible roles of NO, AM and U-II in children with several renal diseases and summarize what is known, and what must be known about these mediators.

Biochemical effects of experimental epidural hematoma on brain parenchyma of rats

INTRODUCTION

The management of epidural hematoma is classified into surgical or conservative treatment according to clinical and radiologic parameters. In the recent years, the number of paper suggesting conservative management has been increasing. The experimental works that have been performed are based on especially the effects of epidural hematomas. Basic pathophysiologic factors on ischemia result of brain trauma are based on biochemical mediators. Nitric oxide (NO) and malondialdehyde (MDA) are the substances that play important roles in brain damage after trauma.

MATERIAL AND METHOD

In this study, 36 rats are divided into three groups (n = 12/group). Epidural hematoma was achieved by 0.1 ml autolog blood in rat epidural space with balloon model. Early and late phase biochemical effects on parenchyma of epidural hematoma operated in a volume which neither alters intracranial pressure (ICP) nor creates shift effect were observed. Biochemical changes of NO and MDA levels were examined in each of three experimental groups.

RESULTS

NO values increased significantly in the early group (6 hours) compared with those in the control group. Difference of NO values between the control and late groups was not significant. An increase has been found in MDA values in the control group compared with those in the early group. MDA values of the late group (30 days) were closer to that of the control group.

CONCLUSION

In this study, considering biochemical results, we have found that conservative volumes which neither increase ICP nor cause brain shift do not lead to permanent changes on brain.

Selective nuclear factor κ-B inhibitors, pyrolidium dithiocarbamate and sulfasalazine, prevent the nephrotoxicity induced by gentamicin

OBJECTIVE

To investigate the effect of selective nuclear factor kappa-B (NFkappa-B) inhibitors, pyrolidium dithiocarbamate (PD) and sulfasalazine (SZ) on renal tubular necrosis and inducible nitric oxide synthase (iNOS) and NFkappa-B expression induced by gentamicin in rats.

MATERIALS AND METHODS

In all, 48 adult male Sprague-Dawley rats were divided into six equal groups; group 1, control; group 2, injected with gentamicin for 10 days (100 mg/kg/day, intraperitoneal, i.p.); group 3, injected with gentamicin plus PD (100 mg/kg/day, i.p.); group 4, injected with gentamicin plus SZ (75 mg/kg/day, i.p.); group 5, injected with gentamicin plus distilled water (vehicle for PD); and group 6, injected with gentamicin plus ammonium hydroxide (75 mg/day, 1 m, vehicle for SZ) for 10 days. At 24 h after the last injection, rats were killed and the renal cortex separated from the medulla. A small sample was fixed in formaldehyde solution for histological and immunohistochemical examination. Blood samples were also taken to assess the serum levels of urea, creatinine, Na(+), K(+) and gamma-glutamyl transpeptidase (GT). Crude extracts of the cortex were used to determine reduced glutathione (GSH-Px), NO and malondialdehyde (MDA). Immunohistochemically, iNOS and the active subunit of NFkappaB, P65, were evaluated using mouse monoclonal antibodies.

RESULTS

On haematoxylin and eosin staining, compared with the controls rats, gentamicin caused widespread tubular necrosis (grade 3 and 4) but in group 3 and 4 there was a marked reduction in the extent of tubular damage. Immunohistochemically there was more marked staining for iNOS and P65 expression in rats given gentamicin than in the control and group 3 and 4 (P < 0.001). In groups 3 and 4 iNOS and P65 expression were significantly less than in rats given only gentamicin. There was no significant difference in serum levels of Na(+), K(+), blood urea nitrogen and creatinine. Compared with control rats, gentamicin caused hyperproteinuria, a marked increase in levels of serum gamma-GT, MDA and NO, and a decrease in GSH-Px (P < 0.001).

CONCLUSION

These results indicate that gentamicin induces iNOS expression through activation of NFkappa-B (P65). It is possible to prevent gentamicin-induced nephrotoxicity using selective NFkappa-B inhibitors.

Plasma and urinary adrenomedullin levels in children with acute pyelonephritis

AIM

Adrenomedullin (AM), a novel peptide recently isolated from pheochromocytoma, eliciting vasorelaxing activity, is the strongest among all known peptides. AM has been detected in the adrenal medulla, cardiac tissue, lung and kidney. Immunohistochemical studies have demonstrated the localization of AM in glomeruli, tubules and collecting cells of the kidney. Clinically, plasma and urinary AM levels are altered in patients with different renal disease. The present study aims to determine plasma and urinary AM levels in children with acute pyelonephritis (APN) and compare the results with a control group.

MATERIALS AND METHODS

The study group was comprised of 19 patients with APN aged 11.6 +/- 3.7 months (range, 6-18 months) and the control group consisted of 16 cases aged 11.5 +/- 3.2 months (range, 7-16 months). Acute pyelonephritis was diagnosed by clinical, laboratory and imaging methods. Plasma and urinary AM levels were measured by high performance liquid chromotography (HPLC).

RESULTS

The plasma AM levels were lower in APN patients (33.40 +/- 2.27 pmol/mL) than in the control group (43.76 +/- 4.27 pmol/mL) (P < 0.001), whereas the urinary AM levels were higher in APN patients (248.58 +/- 140.63 pmol/mg urinary creatinine) than in the control group (49.42 +/- 45.23 pmol/mg) (P < 0.001). Coefficients of correlation between urinary AM levels and C-reactive protein and white blood cells were statistically significant (r = 0.472, P = 0.041; r = 0.555, P = 0.014, respectively).

CONCLUSION

Adrenomedullin, a smooth muscle relaxant peptide that is synthesized in urinary tract tissue might have a role in acute pyelonephritis. However, the importance of AM in the pathogenesis of acute pyelonephritis remains to be determined by further detailed studies.

Plasma and urinary adrenomedullin levels in children with renal parenchymal scar and vesicoureteral reflux

Adrenomedullin (AM) is a strong vasodilator peptide with proven antimitogenic and antiproliferative effects in renal mesangial cells, as well as diuretic and natriuretic actions. Its gene expression is stimulated by endotoxins (lipopolysacharides) and cytokines. Consequently, its plasma and urinary levels are known to deviate from normal levels in many renal diseases. The purpose of this study is to determine plasma and urinary AM levels in children with renal parenchymal scar (RPS) and vesicoureteral reflux (VUR). The study was carried out on 74 children with recurrent urinary tract infections, arranged in groups: 25 patients with RPS with VUR (group I), 16 patients with RPS without VUR (group II), 12 patients with VUR without RPS (group III) and 21 healthy children as the control group. Plasma and urinary AM concentrations were both determined by high performance liquid chromotography (HPLC). Plasma AM was measured as picomoles per milliliter (pM/ml) and urinary AM as pM/mg urinary creatinine. In addition, serum creatinine, creatinine clearance and fractional sodium excretion (FE(Na)) were measured. All cases with RPS and VUR had normal blood pressure levels. The plasma AM levels were higher, although not significantly, in the control group (56.2+/-14.0 pM/ml) than in group I (50.6+/-4.2 pM/ml), group II (49.6+/-3.7 pM/ml) and group III (50.6+/-3.6 pM/ml) ( P =0.162). The urinary AM levels were higher in the control group (80.1+/-33.9 pM/mg) than in the three study groups (52+/-7.6 pM/mg, 58.6+/-7.5 pM/mg and 44.2+/-6.4 pM/mg; P =0.003, P =0.002 and P =0.002, respectively). There were no differences among the 4 groups (group I, group II, group III and the control group) in terms of FE(Na) and creatinine clearance ( P >0.05 and P >0.05, respectively). The finding that diminished urinary AM levels in patients with RPS and VUR implies that AM can be a prognostic factor in the long-term follow-up of cases with these diseases.

Effects of erdosteine on smoking-induced lipid peroxidation in healthy smokers

AIM

Oxidative stress caused by smoking has been implicated in many pulmonary diseases. Smoking causes reductions in plasma nitrate plus nitrite (NOx) concentrations and increases in plasma malondialdehyde (MDA) concentrations, which indicate oxidative stress and lipid peroxidation, respectively. In this study, we investigated the acute effects of smoking a single cigarette on the plasma concentrations of NOx and thiobarbituric acid reactive substances (TBARS) including MDA, and whether administration of erdosteine, a mucolytic and antioxidant agent, affects these parameters.

METHODS

Thirty healthy smokers were included in the study. Subjects smoked a single cigarette in 10 minutes on the study day. For analysis of NOx, TBARS and cotinine, blood was drawn from each subject before and 5 and 30 minutes after smoking. The subjects were then randomly divided into two groups, one receiving placebo and the other erdosteine suspension 175mg/5mL twice daily for 1 month. After this treatment period, the same study protocol was carried out. Two subjects in the placebo and five subjects in the study group were excluded because of noncompliance.

RESULTS

Twenty-three (14 female, 9 male) subjects completed the study. Their mean age was 32 +/- 8 years and their smoking history was 14 +/- 9 pack-years. Baseline NOx, TBARS and cotinine concentrations were similar between the groups. NOx concentrations decreased significantly after smoke exposure. At the end of the treatment period there were no significant differences in NOx, TBARS or cotinine concentrations between the groups. The concentration of TBARS after smoking decreased significantly in the erdosteine-treated group (at 5 minutes: 2.8 +/- 0.5 micromol/L before treatment and 2.3 +/- 0.3 micromol/L after treatment, p < 0.05; at 30 minutes: 2.8 +/- 0.5 micromol/L before treatment and 1.8 +/- 0.7 micromol/L after treatment, p < 0.05). Smoking history was significantly correlated with cotinine concentrations.

CONCLUSION

Acute smoke exposure decreased plasma NOx concentrations in healthy smokers, and this was not changed with erdosteine treatment. However, significant decreases were noted in TBARS concentrations after smoke exposure in the group that received erdosteine, suggesting that short-term erdosteine administration might help prevent smoking-induced lipid peroxidation.

Hereditary disorders of potassium homeostasis

There has been a dramatic recent increase in the understanding of the renal epithelial transport systems with the identification, cloning and characterization of a large number of membrane transport proteins. The aim of this chapter is to integrate this body of knowledge with the understanding of the clinical disorders that accompany gain, loss or dysregulation of function of these transport systems. The specific focus is on the best-defined human clinical syndromes in which there are derangements in potassium (K(+)) homeostasis. The focus is on inherited syndromes, rather than on acquired syndromes due to tubular transport defects, and the therapeutic approaches address chronic derangements of K(+) homeostasis rather than acute interventions directed at life-threatening hyperkalaemia.

Bartter syndrome

PURPOSE OF REVIEW

This review describes recent advances in our understanding of the genetic heterogeneity, pathophysiology and treatment of Bartter syndrome, a group of autosomal recessive disorders that are characterized by markedly reduced or absent salt transport by the thick ascending limb of Henle. Consequently, individuals with Bartter syndrome exhibit renal salt wasting and lowered blood pressure, hypokalemic metabolic alkalosis and hypercalciuria with a variable risk of renal stones.

RECENT FINDINGS

Previously, three genes (SLC12A2, the sodium-potassium-chloride co-transporter; KCNJ1, the ROMK potassium ion channel; ClC-Kb, the basolateral chloride ion channel) had been identified as causing antenatal and 'classic' Bartter syndrome. Two additional genes have now been identified. Barttin is a beta-subunit that is required for the trafficking of CLC-K (both ClC-Ka and ClC-Kb) channels to the plasma membrane in both the thick ascending limb and the marginal cells in the scala media of the inner ear that secrete potassium ion-rich endolymph. Loss-of-function mutations in barttin thus cause Bartter syndrome with sensorineural deafness. In addition, severe gain-of-function mutations in the extracellular calcium ion-sensing receptor can result in a Bartter phenotype because activation of this G protein-coupled receptor inhibits salt transport in the thick ascending limb (a furosemide-like effect).

SUMMARY

Five genes have been identified as causing Bartter syndrome (types I-V), with the unifying pathophysiology being the loss of salt transport by the thick ascending limb. Phenotypic differences in Bartter types I-V relate to the specific physiological roles of the individual genes in the kidney and other organ systems.

Cell and molecular biology of the multifunctional peptide, adrenomedullin

Adrenomedullin (AM) is a recently discovered regulatory peptide involved in many functions including vasodilatation, electrolyte balance, neurotransmission, growth, and hormone secretion regulation, among others. This 52-amino acid peptide is expressed by specific cell types in many organs throughout the body. A complex receptor system has been described for AM; it requires at least the presence of a seven-transmembrane-domain G-protein-coupled receptor, a single-transmembrane-domain receptor activity modifying protein, and a receptor component protein needed to establish the connection with the downstream signal transduction pathway, which usually involves cyclicAMP. In addition, a serum-binding protein regulates the biological actions of AM, frequently by increasing AM functional attributes. Changes in levels of circulating AM correlate with several critical diseases, including cardiovascular and renal disorders, sepsis, cancer, and diabetes. Whether AM is a causal agent, a protective reaction, or just a marker for these diseases is currently under investigation. New technologies seeking to elevate and/or reduce AM levels are being investigated as potential therapeutic avenues.

Renal genetic disorders related to K+ and Mg2+

The recent knowledge of the renal epithelial transport systems has exploded with the identification, cloning, and characterization of a large number of membrane transport proteins. The fundamental aspects of these transporters are beginning to emerge at the molecular level and are summarized in the accompanying contributions in this volume of the Annual Review of Physiology. The aim of my review is to integrate this body of knowledge with the understanding of the clinical disorders of human mineral homeostasis that accompany gain, loss, or dysregulation of function of these transport systems. The specific focus is on the best defined human clinical syndromes in which there are derangements in K(+) and Mg(2+) homeostasis.

A review of the biological properties and clinical implications of adrenomedullin and proadrenomedullin N-terminal 20 peptide (PAMP), hypotensive and vasodilating peptides

Adrenomedullin (AM), identified from pheochromocytoma and having 52 amino acids, elicits a long-lasting vasodilatation and diuresis. AM is mainly mediated by the intracellular adenylate cyclase coupled with cyclic adenosine monophosphate (cAMP) and nitric oxide (NO) -cyclic guanosine monophosphate (cGMP) pathway through its specific receptor. The calcitonin receptor-like receptor (CLCR) and receptor-activity modifying protein (RAMP) 2 or RAMP3 models have been proposed as the candidate receptor. AM is produced mainly in cardiovascular tissues in response to stimuli such as shear stress and stretch, hormonal factors and cytokines. Recently established AM knockout mice lines revealed that AM is essential for development of vitelline vessels of embryo. Plasma AM levels elevate in cardiovascular diseases such as heart failure, hypertension and septic shock, where AM may play protective roles through its characteristic biological activities. Human AM gene delivery improves hypertension, renal function, cardiac hypertrophy and nephrosclerosis in the hypertensive rats. AM decreases cardiac preload and afterload and improves cardiac contractility and diuresis in patients with heart failure and hypertension. Advances in gene engineering and receptor studies may contribute to further understandings of biological implication and therapeutic availability of AM.