Atrial granules in the dog heart after cardiac denervation

Summary Because the increase in sodium excretion during left atrial distension in conscious dogs is abolished after chronic cardiac denervation, we have investigated whether this is a result of the disappearance of specific atrial granules. Electron microscopy and light-microscopical and ultrastructural immunohistochemistry of canine atria show that atrial granules displaying immunoreactivity for cardiac hormones of the cardiodilatin/atrial natriuretic polypeptide (CDD/ANP) family are still present in denervated left and right atria, although reduced in quantity. It is concluded that the atrial-induced natriuresis is not only related to the existence of specific atrial granules. The functional link between atrial-induced natriuresis provoked by atrial distension and the release of atrial polypeptide hormones remains uncertain because the denervated heart can secrete CDD although the diuretic-natriuretic effect is altered.     

Chemical synthesis of beta-defensins and LEAP-1/hepcidin.

A large and steadily growing subfamily of antimicrobially active peptides of animals and plants is formed by the defensins, which are highly disulfide-bonded, cationic peptides with a molecular mass of about 4 kDa. The synthesis of the human beta-defensins 1 and 2 (hBD-1, hBD-2) as well as of the novel murine beta-defensins 7 and 8 (mBD-7 and mBD-8) is reported. The peptides were synthesized by solid-phase peptide synthesis using fluorenylmethoxycarbonyl chemistry. The linear products were oxidized in the presence of the cysteine/cystine redox system to the biologically active molecules. The correct disulfide connectivity of the resulting cyclic products was partly verified by mass spectrometry and sequence analysis of the fragments obtained after tryptic cleavage. In addition, the recently discovered antimicrobially active human peptide LEAP-1/hepcidin, which contains four disulfide bonds, was successfully synthesized and subsequently oxidized. For Liver-expressed anti microbial peptide (LEAP)-1/hepcidin and hBD-1, the identity of native and synthetic peptides was demonstrated by high-pressure liquid chromatography and capillary electrophoretic analysis. The general synthetic procedure is suitable to rapidly perform the total chemical synthesis of novel fully bioactive defensins, which are expected to be identified soon, as well as of structurally modified analogs.     

Chemoattraction of macrophages, T lymphocytes, and mast cells is evolutionarily conserved within the human alpha-defensin family

Human defensins are natural peptide antibiotics. On the basis of the position and bonding of six conserved cysteine residues, they are divided into two families, designated alpha- and beta-defensins. Human alpha-defensins are expressed predominantly in neutrophils (human neutrophil peptides (HNP) 1-4) or intestinal Paneth cells (human defensins (HD) 5 and 6). Although alpha-defensins have been implicated in the pathogenesis of inflammatory bowel disease, their immunomodulatory functions are poorly understood. In the present study, HNP-1, HNP-3, and HD5 were found to be potent chemotaxins for macrophages but not dendritic cells using Galphai proteins and MAPK as signal transducers. Alpha-defensins were also chemoattractive for the human mast cell line HMC-1 but lacked, in contrast to beta-defensins, the ability to induce intracellular calcium fluxes. Furthermore, HNP-1, HNP-3, and HD5 comparably mobilized naive as well as memory T lymphocytes. Using the protein kinase C (PKC) inhibitors GF109 and G?6976, we observed a PKC-independent functional desensitization to occur between human alpha-defensins, which suggests a common receptor for HNP-1, HNP-3, and HD5 on immune cells. This alpha-defensin receptor was subject to heterologous desensitization by the PKC activator PMA and to PKC-dependent cross-desensitization by human beta-defensins. Conversely, alpha-defensins desensitized beta-defensin-mediated migration of immune cells in a PKC-dependent manner, suggesting unique receptors for both defensin families. Taken together, our observations indicate that chemoattraction of macrophages, T lymphocytes, and mast cells represents an immunomodulatory function which is evolutionarily conserved within the human alpha-defensin family and tightly regulated by beta-defensins.     

In vivo processed fragments of IGF binding protein-2 copurified with bioactive IGF-II

Proteolysis of insulin-like growth factor binding proteins (IGFBPs), the major carrier of insulin-like growth factors (IGFs) in the circulation, is an essential mechanism to regulate the bioavailability and half-live of IGFs. Screening for peptides in human hemofiltrate, stimulating the survival of PC-12 cells, resulted in the isolation of C-terminal IGFBP-2 fragments and intact IGF-II co-eluting during the chromatographic purification procedure. The IGFBP-2 fragments exhibited molecular masses of 12.7 and 12.9kDa and started with Gly169 and Gly167, respectively. The fragments were able to bind both IGFs. The stimulatory effect of the purified fraction on the survival of the PC-12 cells could be assigned exclusively to IGF-II, since it was abolished by the addition of neutralizing IGF-II antibodies. We suggest that in the circulation IGF-II is not only complexed with intact IGFBP but also with processed IGFBP-2 fragments not impairing the biological activity of IGF-II.     

Comparison of the pharmacokinetics,safety and tolerability of two concentrations of a new liquid recombinant human growth hormone formulation versus the freeze-dried formulation

Background  

Somatropin is recombinant human growth hormone (GH) used for the treatment of growth failure in children and GH deficiency in adults. Two concentrations of a liquid formulation have been developed: 5.83 and 8.0 mg/mL. This trial compared the pharmacokinetics (PK), safety and tolerability of these two liquid concentrations against the freeze-dried (FD) formulation in healthy volunteers.     

Dopamine-β-hydroxylase-, neurotensin-, substance P-, vasoactive intestinal polypeptide- and enkephalin-immunohistochemistry of paravertebral and prevertebral ganglia in the cat

Summary Para and prevertebral ganglia of the cat were investigated for immunoreactivity (IR) against neurotensin (NT), vasoactive intestinal polypeptide (VIP), substance P (SP) and enkephalin (ENK). Dopamine--hydroxylase- (DBH)-IR was studied in consecutive sections to correlate the distribution of noradrenergic/adrenergic neurons with that of peptidergic nerve fibres and cells.In paravertebral (cervical and thoracic) ganglia, NT-IR or ENK-IR nerve fibres were seen in areas in which DBH-IR fibre networks also occurred. NT-IR varicosities were often in close contact with perikarya of principal ganglionic cells on which DBH-IR varicosities also terminated. Such an association was rarely seen between ENK-IR and DBH-IR fibre baskets. NT-IR and ENK-IR fibre baskets were not found to occur around the same principal ganglionic cell. The distribution of VIP-IR and SP-IR nerve fibres did not coincide with that of DBH-IR fibres.In prevertebral ganglia (celiac-superior mesenteric and inferior mesenteric) DBH-IR or VIP-IR varicosities surrounded the majority of principal ganglionic neurons. ENK-IR or SP-IR fibres were closely associated with only a minority of the neurons; NT-IR networks were rather sparse. Some principal neurons were approached by DBH-IR fibres and by different peptide-IR fibres.In paravertebral ganglia some principal ganglionic cells contained VIP-IR, a few of which were also surrounded by NT-IR varicosities. VIP-IR perikarya in prevertebral ganglia were extremely rare. No NT-IR, SP-IR or ENK-IR principal ganglionic cells were found.Glomus-like paraganglionic cell clusters in paravertebral and prevertebral ganglia exhibited DBH-IR cell bodies. Moreover, the clusters also contained ENK-IR or SP-IR cells. NT-IR varicosities were observed adjacent to clustered paraganglionic cells. Only few singly located paraganglionic cells were NT-IR or ENK-IR.The differential distribution of peptide-IR nerve endings in the investigated ganglia suggests a regulation of impulse transmission that seems to be related to the target organs.Fellow of the Heisenberg foundationSupported by the DFG, grants He 919/5, Re 520/1-2, and SFB 90 Carvas, Heidelberg