The acute GH release stimulated by the synthetic hexapeptide, His-DTrp-Ala-Trp-DPhe-Lys-NH2 [GH releasing peptide (GHRP)], was determined in 18 normal men and compared with the effects of GH-releasing hormone, GHRH-(1-44)-NH2. Specificity of effect was assessed by measurement of serum PRL, LH, TSH, and cortisol. GHRP was administered at doses of 0.1, 0.3, and 1.0 microgram/kg by iv bolus. GHRH at a dose of 1.0 microgram/kg was administered alone and together with various does of GHRP. No adverse clinical effects of laboratory abnormalities were observed in response to GHRP. A side-effect of mild facial flushing of 1- to 3-min duration occurred in 16 of the 18 subjects who received GHRH-(1-44)-NH2. Mean (+/- SEM) peak serum GH levels after injection of placebo and 0.1, 0.3, and 1.0 microgram/kg GHRP were 1.2 +/- 0.3, 7.6 +/- 2.5, 16.5 +/- 4.1, and 68.7 +/- 15.5 micrograms/L, respectively. The submaximal dosages of 0.1 and 0.3 microgram/kg GHRP plus 1 microgram/kg GHRH stimulated GH release synergistically. Serum PRL and cortisol levels rose about 2-fold above basal levels only at the 1 microgram/kg dose of GHRP, and there were no changes in serum LH and TSH over the first hour after administration of the peptide(s). GHRP is a potent secretagogue of GH in normal men. Since GHRP and GHRH together stimulate GH release synergistically, these results suggest that GHRP and GHRH act independently. This supports our hypothesis that the GH-releasing activity of GHRP reflects a new physiological system in need of further characterization in animals and man.

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The baseline data from GLORIA-AF phase 2 demonstrate that in newly diagnosed nonvalvular atrial fibrillation patients, NOAC have been highly adopted into practice, becoming more frequently prescribed than VKA in Europe and North America. Worldwide, however, a large proportion of patients remain undertreated, particularly in Asia and North America. (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients With Atrial Fibrillation [GLORIA-AF]; NCT01468701).

Analogs of somatostatin are being investigated clinically for the treatment of various malignancies, including brain tumors. We studied the ability of three therapeutically promising radioactively labeled somatostatin octapeptide analogs, RC-160, RC-121, and RC-161, to cross the blood-brain barrier (BBB) after peripheral or central injection. After i.v. injection, intact RC-160 was recovered from the blood and the brain. The entry rates were different for each compound but were generally low. By contrast, entry across the intact BBB increased 220 times when RC-160 was given in a serum-free perfusate. This suggests that some serum-related factor, probably the previously described protein binding or an aggregation-promoting factor, is the main determinant in limiting the blood-to-brain passage of somatostatin analogs. Entry into the brain was not inhibited by the addition of unlabeled analog to the perfusate, showing that passage was probably by diffusion across the membranes that comprise the BBB rather than by saturable transport. By contrast, a saturable system was found to transport peptide out of the central nervous system (CNS). The clearance from the CNS of RC-160 and RC-121, but not RC-161, was faster than could be accounted for by reabsorption of cerebrospinal fluid. Transport of radioactively labeled RC-160 out of the CNS was inhibited by unlabeled RC-160 or somatostatin but was not affected by some other peptides known to cross the BBB by their own transport systems. More than 80% of the radioactivity recovered from the blood after intracerebroventricular injection of RC-160 was eluted by HPLC at the position of the labeled analog, showing that the peptide had crossed the BBB in intact form. Our results indicate the presence of a saturable transport system in one direction across the BBB for some superactive analogs of somatostatin. Several problems impede the therapeutic use of naturally occurring peptides, including poor absorption by the gastrointestinal tract, a short half-life in the circulation, and multiple actions. For use in the central nervous system (CNS), limited passage across the blood-brain barrier (BBB) may also be a factor. Most of these problems have been solved in the case of somatostatin by the development of analogs. Circulating half-life has been increased by the development of enzymatically resistant analogs. In addition, the administration of the analogs in sustained-delivery systems (microcapsules) permits the maintenance of high therapeutic blood levels (6, 10, 17). Many analogs show selectivity in their activities. For example, RC-121 is about 100 times more potent than somatostatin-(1-14) tetradecapeptide in the inhibition of growth hormone release but <5 times more potent in the inhibition of gastric acid release (17,18).In contrast, essentially no work has been done to investigate the ability of somatostatin analogs to cross the BBB, although it is known that radioactively iodinated Tyrsomatostatin-(1-14) pentadecapeptide can cross (19). This relationship to the BBB...

The host-encoded Perforin-2 (encoded by the macrophage-expressed gene 1, Mpeg1), which possesses a pore-forming MACPF domain, reduces the viability of bacterial pathogens that reside within membrane-bound compartments. Here, it is shown that Perforin-2 also restricts the proliferation of the intracytosolic pathogen Listeria monocytogenes. Within a few hours of systemic infection, the massive proliferation of L. monocytogenes in Perforin-2 ؊/؊ mice leads to a rapid appearance of acute disease symptoms. We go on to show in cultured Perforin-2 ؊/؊ cells that the vacuole-to-cytosol transitioning of L. monocytogenes is greatly accelerated. Unexpectedly, we found that in Perforin-2 ؊/؊ macrophages, Listeria-containing vacuoles quickly (<15 min) acidify, and that this was coincident with greater virulence gene expression, likely accounting for the more rapid translocation of L. monocytogenes to its replicative niche in the cytosol. This hypothesis was supported by our finding that a L. monocytogenes strain expressing virulence factors at a constitutively high level replicated equally well in Perforin-2 ؉/؉ and Perforin-2 ؊/؊ macrophages. Our findings suggest that the protective role of Perforin-2 against listeriosis is based on it limiting the intracellular replication of the pathogen. This cellular activity of Perforin-2 may derive from it regulating the acidification of Listeria-containing vacuoles, thereby depriving the pathogen of favorable intracellular conditions that promote its virulence gene activity. Both extracellular bacteria and virus-infected cells are targeted by innate defense responses that employ pore-forming proteins (1). Extracellular bacteria that become bound with the complement factor C3b and the C5b-8 complex trigger the polymerization of C9, resulting in a doughnut-shaped pore with a diameter of 100 Å that constitutes the membrane attack complex (MAC) (2-4). Similarly, virus-infected cells are recognized and eliminated by natural killer (NK) and cytotoxic T lymphocytes (CTL) that, as part of their respective killing programs, secrete Perforin-1, which forms a cluster of lethal pores in the membrane of the infected cell (5, 6). The complement proteins C6 to C9 and Perforin-1 all possess a membrane-attack-complex-perforin (MACPF) domain, which mediates the homopolymerization process that drives pore formation.A gene predicted to encode a third MACPF-containing protein, macrophage expressed gene-1 (Mpeg1), recently has been described in a number of invertebrates and zebrafish and plays a role in innate immune responses in these species to bacterial pathogens (7-11). Phylogenic analyses indicate that the MACPF domain of Mpeg1 is the ancestor of the MACPF domains in the complement and Perforin-1 proteins (12). Interestingly, although homologous Mpeg1 genes are found in most metazoan genomes spanning from sponges to humans, Mpeg1, or MACPF-encoding genes more generally, so far have not been identified in nonmetazoan clades of eukaryotes. However, the MACPF domain itself bears a striking structural si...