Atrial natriuretic peptide in human urine

Summary A highly sensitive radioimmunoassay to measure atrial natriuretic peptide (ANP) concentration in urine has been established, and its clinical usefulness is presented. ANP in urine was stable at 4° C for several days and was easily measured by our radioimmunoassay. The average ANP excretion in 65 healthy persons was 25.0±1.4 ng/day (mean ± SEM) and the fractional excretion of ANP was 0.7±0.05%. In 14 patients with congestive heart failure, the average ANP excretion was 119.2±29.4 ng/day, which decreased to 53.3±11.0 after successful treatment.Abbreviations ANP atrial natriuretic peptide - hANP human atrial natriuretic peptide - RIA radioimmunoasay - NSB non specific bound - FE_ANP the fractional excretion of atrial natriuretic peptide - FE_Na the fractional excretion of sodium - SIADH the syngrome of inappropriate secretion of antidiuretic hormone     

Atrial natriuretic factor (ANF) does not affect ion transport in human intestine but does in porcine intestine

The aim of this study was to test whether atrial natriuretic factor (ANF) exerts any effect on human intestinal ion transport, and the porcine intestine was used as a positive control of ANF's effects. Tissues from human proximal (n = 6) and distal (n = 6) colons, and from distal ileum (n = 6) were mounted in Ussing chambers, and short circuit current (I_sc) was measured subsequent to serosal application of ANF (10^--⁶ m), 8–Br-cyclic guanosine monophosphate (8–Br-cGMP) (10^--⁴ m), and theophylline (10^--² m). ANF did not affect I_sc whereas 8–Br-cGMP increased I_sc by 28 (8–53), 16 (3–36), and 16 (5–41) μA cm^-2 in the distal colon (DC), proximal colon (PC) and distal ileum (DI), respectively. Likewise, transepithelial potential difference (PD) became more negative by 5.0 (0.6–8.9), 2.5 (0.4–4.0) and 0.9 (0.3–2.3) mV in DC, PC, and DI, respectively, subsequent to addition of 8–Br-cGMP. I_sc and PD were further increased by theophylline. Additional radio-isotope flux studies in human colon revealed that ANF did not affect electroneutral sodium and chloride transport either. For comparison, ANF (10^--⁶ m) was administered to large intestinal tissues from young pigs in which ANF induced a significant increase in I_sc which was comparable to the 8–Br-cGMP response in humans. The porcine I_sc response was partly inhibited by chloride-free solution on the serosal side, by serosal application of bumetanide (10^--⁴ m) and BaCl₂ (10^--³ m), and mucosal application of the chloride-channel blocker diphenylamine-2–carboxylate (DPC) (10^--³ m). Mucosal amiloride (10^--⁵ m) pre-treatment reduced baseline I_sc but did not affect the porcine intestinal I_sc response to ANF. In vitro radio-autography demonstrated specific binding sites for ANF in porcine distal colon, whereas no apparent labelling was observed in human distal colon. These findings suggest that the lack of effect of ANF on sodium and chloride transport in human distal ileum and colon is probably due to lack of ANF receptors. In the porcine intestine, however, the I_S0 response induced by ANF seems to involve stimulation of electrogenic chloride secretion, whereas electrogenic sodium absorption seems unaffected.     

Neuraminidase- and benzalkonium chloride-dependent inhibition of basic peptide-induced rat mast cell secretion

Two types of inhibition of basic peptide-induced rat mast cell secretion are reported. Pretreatment of rat peritoneal mast cells with Vibrio comma neuraminidase, an enzyme which cleaves sialic acid from oligosaccharides, led to inhibition of 5-hydroxytryptamine release induced by the basic peptides polylysine, corticotropin_1–24 and a decapeptide sequence of human IgE. Inhibition was similarly observed when mast cells were challenged in the presence of the cationic cell membrane-active substance benzalkonium chloride. It is postulated that both of these experimental procedures inhibit basic peptide-induced secretion by depletion of cell surface negative charge. Sialic acid itself does not act as a specific receptor for basic peptides, since a molar excess of sialic acid in free solution failed to inhibit secretion by binding to basic peptides in the fluid phase.     

Atrial amyloid deposits in the failing human heart display both atrial and brain natriuretic peptide-like immunoreactivity

Atrial amyloid deposits are common in the ageing human heart and contain alpha-atrial natriuretic peptide (proANP99-126) immunoreactivity. However, atrial myocytes secrete both amino and carboxy terminal fragments of the ANP prohormone (proANP1-126) and also express an homologous, but separate brain natriuretic peptide (BNP). Characteristic amyloid deposits were identified in the atria of 9/22 patients (26-63 years of age) with end-stage heart failure. Amyloid fibrils displayed immunoreactivity for both amino and carboxy terminal fragments of proANP1-126 and for the distinct BNP sequence. As in other endocrine organs, both mature and precursor peptide sequences appear to be constituents of amyloid fibrils. Whilst immunoreactivity for cardiac peptide hormones is co-localized in atrial amyloid deposits, it is uncertain whether the increase in natriuretic peptide expression which accompanies cardiac failure contributes to the incidence of isolated atrial amyloidosis.     

Endocrine differentiation of extra-pulmonary small cell carcinoma demonstrated by immunohistochemistry using antibodies to PGP 9.5, neuron-specific enolase and the C-flanking peptide of human pro-bombesin

Several recent studies have confirmed the endocrine nature of small cell carcinoma of the lung. In extra-pulmonary sites, small cell 'undifferentiated' carcinomas have classical morphological features similar to their pulmonary counterpart. We therefore investigated, using immunocytochemistry, the possibility that the non-pulmonary neoplasms may also be endocrine in nature. Sections of 29 small cell carcinomas from oesophagus, stomach, larynx, colon and urinary bladder were immunostained using antisera to protein gene product 9.5 (PGP 9.5), neuron-specific enolase (NSE), cytokeratin, leucocyte common antigen and peptides including bombesin, the C-flanking peptide of human probombesin, adrenocorticotrophic hormone, neurotensin, calcitonin and pancreatic polypeptide. All the tumours showed immunoreactivity for at least one of the two general endocrine markers PGP 9.5 and NSE. Twenty-three of the 29 cases were immunoreactive for PGP 9.5, 27 for NSE. All were positive for cytokeratin and negative for leucocyte common antigen. Of the regulatory peptides, immunoreactivity was obtained with antisera to bombesin (one case), the C-flanking peptide of human pro-bombesin (14 cases), adrenocorticotrophic hormone (one case) and calcitonin (three cases). No PGP 9.5-, NSE- or peptide-like immunoreactivity was detected in 25 control tumours from similar sites, including lymphomas and poorly differentiated tumours. These results suggest that non-pulmonary small cell carcinoma has an endocrine character.     

Vp130, a chloroviral surface protein that interacts with the host Chlorella cell wall

A protein, Vp130, that interacts with the host cell wall was isolated from Chlorovirus CVK2. From its peptide sequence, the gene for Vp130 was identified on the PBCV-1 genomic sequence as an ORF combining A140R and A145R. In Vp130, the N-terminus was somehow modified and the C-terminus was occupied by 23-26 tandem repeats of a PAPK motif. In the internal region, Vp130 contained seven repeats of 70-73 amino acids, each copy of which was separated by PAPK sequences. This protein was well conserved among NC64A viruses. A recombinant rVp130N protein formed in Escherichia coli was shown not only to bind directly to the host cell wall in vitro but also to specifically bind to the host cells, as demonstrated by fluorescence microscopy. Because externally added rVp130N competed with CVK2 to bind to host cells, Vp130 is most likely to be a host-recognizing protein on the virion.     

Effect of atrial natriuretic factor and cyclic guanosine monophosphate on water and urea transport in the inner medullary collecting duct

We examined the action of high (2×10^–8M) and low (6×10^–9M) concentrations of atrial natriuretic factor (ANF) on water and urea transport in the rat inner medullary collecting duct (IMCD) using the in vitro microperfusion technique. We measured the hydraulic conductivity (Lp ×10^–6 cm/atm per second) and both lumen-to-bath (P _u(lb)) and bath-to-lumen (P _u(bl)) ¹⁴C-urea permeabilities (P _u× 10^–5 cm/s) in the absence and in the presence of vasopressin (VP). High concentrations of ANF were able to inhibit the maximum activity of (50 U/ml) VP-stimulated L _p but physiological concentration of ANF inhibit only submaximum activity (10 U/ml) of VP-stimulated L _p. The hydrosmotic effect of dibutyryl-cyclic 3,5 adenosine monophosphate (cAMP) (10^–4M) was unchanged by high concentrations of ANF (2×10^–8M). Also we found that high (10^–4M) and low (10^–6M) concentrations of exogenous cyclic 3,5-guanosine monophosphate (GMP) while unable to change the Lp in the absence of VP, decreased the maximum activity of VP-stimulated Lp significantly. We also found that ANF inhibits partially and in a reversible manner the VP-stimulated P _u(lb) but not the VP-stimulated P _u(bl). These results demonstrated that plasma concentrations of ANF observed during volume expansion (10^–10M) are able to inhibit submaximum activity of VP-stimulated (10 U/ml) L _p in the rat IMCD, this effect seems to occur before cAMP formation and it appears to be mediated by cGMP. ANF (6× 10^–9M) also reduced the VP-stimulated urea outflux. Therefore, the increase in water excretion produced by ANF could be explained, at least in part, by the inhibition by ANF of vasopressin effects on water and urea transport in the IMCD.This study was presented in part at the VI Latin American Congress of Nephrology, Brazil, October 1985 and at the X^th International Congress of Nephrology, London, July 1987.     

Content of Autoantibodies to Bradykinin and β-Amyloid1-42 as a Criterion for Biochemical Differences between Alzheimer's Dementias

We measured serum content of autoantibodies to -amyloid protein A_1-42, its neurotoxic fragment A_25-35, vasopressin, bradykinin, thrombin, antithrombin III, ₂-macroglobulin, and angiotensin II in patients with various forms of Alzheimer's dementias, including presenile and senile dementias of the Alzheimer type. The ratio of antibradykinin and anti-A_1-42 autoantibody contents differed by 39% in these patients. Our results can be used for the development of a new biochemical method for differential diagnostics of dementias of the Alzheimer type.     

Effect of hydra peptide morphogen on cyclic nucleotide levels in injured tissues

Novokuznetsk Branch, Central Research Institute of Prosthetics. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 108, No. 10, pp. 486–487, October, 1989.     

Human defensins

Antimicrobial peptides are small, cationic, amphiphilic peptides of 12–50 amino acids with microbicidal activity against both bacteria and fungi. The eukaryotic antimicrobial peptides may be divided into four distinct groups according to their structural features: cysteine-free -helices, extended cysteine-free -helices with a predominance of one or two amino acids, loop structures with one intramolecular disulfide bond, and -sheet structures which are stabilised by two or three intramolecular disulfide bonds. Mammalian defensins are part of the last-mentioned group. The mammalian defensins can be subdivided into three main classes according to their structural differences: the -defensins, -defensins and the recently described -defensins. Mammalian -defensins are predominantly found in neutrophils and in small intestinal Paneth cells, whereas mammalian -defensins have been isolated from both leukocytes and epithelial cells. Recently, two novel human -defensins, human beta-defensin-3 (HBD-3), and human beta-defensin-4 (HBD-4) have been discovered. Similar to HBD-1 and HBD-2, HBD-3 has microbicidal activity towards the Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli) and the yeasts Candida albicans and Malassezia furfur. In addition, HBD-3 kills Gram-positive bacteria such as Streptococcus pyogenes or Staphylococcus aureus, including multi-resistant S. aureus strains, and even vancomycin-resistant Enterococcus faecium. In contrast to HBD-1 and HBD-2, significant expression of HBD-3 has been demonstrated in non-epithelial tissues, such as leukocytes, heart and skeletal muscle. HBD-4 is expressed in certain epithelia and in neutrophils. Its bactericidal activity against P. aeruginosa is stronger than that of the other known -defensins. Here we present an overview of human antimicrobial peptides with some emphasis on their antifungal properties.J.J. Schneider and A. Unholzer contributed equally to this work