Bombinins, antimicrobial peptides from Bombina species

The skin secretions of Bombina species contain peptides and small proteins with interesting biological properties. These include bombesin, thyrotropin releasing hormone, BSTI and Bv8. In this review, the biosynthesis and antimicrobial activity of two groups of peptides, bombinins and bombinins H, are described. To date, these have only been found in Bombina skin. They are derived from common precursors containing one or two bombinin copies at the amino and a single bombinin H at the carboxyl end. Bombinins are active against Gram-positive and Gram-negative bacteria and fungi but virtually inactive in haemolysis assays. Conversely, bombinins H have lower bactericidal activities but lyse erythrocytes. In the skin secretions, bombinins H are present in two sizes with either 20 or 17 amino acids. Moreover, they occur as epimers with either an l- or a d-amino acid at position 2. An enzyme catalyzing this inversion of chirality of an amino acid in peptide linkage has been isolated from Bombina skin secretions. In different tests, also with different stages of the life cycle of Leishmania parasites, the d-forms were found to be more active. Biophysical studies have yielded some insight into the different behaviours of the epimers in model membranes.     

Targeting integrins: insights into structure and activity of cyclic RGD pentapeptide mimics containing azabicycloalkane amino acids

A small library of cyclic RGD pentapeptide mimics incorporating stereoisomeric 5,6- and 5,7-fused bicyclic lactams was synthesized. This library was found to contain high-affinity ligands for the alpha(v)beta3 integrin. The aim of this study was to investigate activity, selectivity, and structure of these ligands in order to identify new specific alpha(v)-integrin antagonists that could be evaluated as tumor angiogenesis inhibitors. In vitro screening, including receptor-binding assays to purified alpha(v)beta3, alpha(v)beta5, and alpha5beta1 integrins, and platelet aggregation assay, revealed ST1646 as a potent, highly selective alpha(v)beta3/alpha(v)beta5 integrin antagonist. Structure determination of the cyclic RGD pentapeptide mimics performed by a combination of NMR spectroscopy, and molecular mechanics and dynamics calculations showed a strong dependence of the RGD cyclopeptide conformation on lactam ring size and stereochemistry. ST1646 revealed the highest ability within the library to adopt the proper RGD orientation required for binding to the alpha(v)beta3 integrin, as deduced from the recently solved crystal structure of the extracellular segment of integrin alpha(v)beta3 in complex with a cyclic pentapeptide ligand.     

Early Response to Sibutramine in Patients Not Meeting Current Label Criteria: Preliminary Analysis of SCOUT Lead‐in Period

The Sibutramine Cardiovascular Outcomes (SCOUT) trial protocol defines a patient population predominantly outside current European Union label criteria. This article explores responses to sibutramine during the 6‐week, single‐blind, lead‐in period between patients who conformed to the label requirements (“conformers”) and those who did not (“nonconformers”). SCOUT is an ongoing, randomized, double‐blind, placebo‐controlled outcome trial in overweight/obese patients at high risk of a cardiovascular event. In total, 10,742 patients received sibutramine and weight management during the lead‐in period. Initial responses were assessed post hoc in label conformers and nonconformers. Of that 8.1% patients met label criteria; 91.9%, the majority with cardiovascular disease and/or blood pressure >145/90 mm Hg, were nonconformers. Conformers and nonconformers had similar reductions in body weight (median change ?2.2 kg) and waist circumference (women: ?2.0 cm for both groups; men: ?1.5 cm vs. ?2.0 cm for conformers and nonconformers, respectively) over the 6‐week period. Greater blood pressure falls were evident in nonconformers (median change ?3.5/?1.0 vs. ?1.0/0.0 mm Hg). Both groups had small pulse rate increases; median 1.5 bpm (nonconformers) vs. 3.0 bpm (conformers). There was a low incidence of serious adverse events (conformers: 1.0%; nonconformers: 2.8%) and ～93% of patients in both groups completed the 6‐week period. The SCOUT lead‐in period evaluating weight management with sibutramine confirms its good tolerability and efficacy in patients who meet current label criteria. Preliminary data from high‐risk patients for whom sibutramine is currently contraindicated suggest a low discontinuation rate and few serious adverse events but confirmation from the SCOUT outcome data is needed.     

Rheumatoid nodule and combined pulmonary carcinoma: topographic correlations; a case report and review of the literature

An association between rheumatoid arthritis (RA) and malignancies has been ascertained and patients with RA appear to be at higher risk of lymphoma and lung cancer. The higher risk of the latter malignancy may be related to rheumatoid interstitial lung disease and immunosuppressive therapies. Herein we illustrate the case of a 59-year-old male smoker affected by RA and treated with cortisone, methotrexate and TNF-α antagonists, who underwent right lower lobectomy for a nodular lesion. On microscopic examination, the lesion consisted of two distinct areas: a central area of fibrinoid necrosis, bordered by histiocytes in a palisaded arrangement, lymphocytes and a 0.4 cm thick peripheral area constituted by a combined small cell anaplastic carcinoma, adenocarcinoma and squamous cell carcinoma. The combination of three histotypes is very rare in such a small tumour. In our case, it may be hypothesized that synchronous, heterogeneous mutations occurred in different type of committed cells or in stem cells, due to the production of cytokines by RA nodule histiocytes and lymphocytes, which are contiguous to the carcinomatous area. Since few studies have evaluated the topographic correlation between tumors and rheumatoid lung lesions, further morphological and molecular studies are needed to clarify this association and the pathogenetic relationship between RA and cancer of the lung.     

Disruption of CD40/CD40L interaction influences the course of Cryptococcus neoformans infection

CD40 signaling has been implicated in various pathogenic processes such as chronic inflammatory disease, graft-versus-host disease, autoimmune disease and cancer. We previously demonstrated in an in vitro system that the CD40/CD40L pathway mediates late interleukin (IL) 12 production in response to Cryptococcus neoformans. The purpose of this study was to examine the course of C. neoformans infection in the absence of CD40/CD40L costimulation. We compared infection in mice genetically lacking CD40L (CD40L(-/-)) and in the wild-type counterpart. The animals were injected intratracheally with C. neoformans and monitored for clearance of the organism and the development of cellular immune response. CD40L(-/-) mice exhibited an exacerbation of infection, evaluated as scarce inflammatory response in the lung, that mirrored an increase of fungal burden. This correlated with impairment of nitrite production and antimicrobial activity by macrophages against C. neoformans and unrelated microorganisms such as Candida albicans. Moreover, IL-12 production by splenic macrophages was diminished in CD40L(-/-) mice and interferon-gamma production by CD4 and CD8 T cells was decreased. CD4 T cells retained the ability to express a costimulatory molecule, CTLA-4, but showed a decrease in CD28 expression. This latter molecule is implicated in a positive effect on proliferation, cytokine production and survival of T cells. Collectively these data demonstrate that absence of CD40L correlates with (i) reduced antimicrobial activity of natural effector cells; (ii) reduction of the magnitude of T cell response; and (iii) increase of fungal growth in the brain. These findings suggest that disruption of CD40/CD40L may be deleterious for development of an efficient immune response to C. neoformans and may identify potential molecular targets for novel immunotherapeutic approaches     

Metabolic alterations in K562 cells exposed to taxol and tyrphostin AG957: 1H NMR and biochemical studies

K562 cells exposed for 3 h to taxol or taxol plus tyrphostin AG957 exhibited a significant variation in the concentration of the water-soluble metabolites glutathione, myo-inositol and phosphorylcholine, as evaluated by (1)H NMR up to 72 h incubation in drug-free medium. Cells treated with both drugs showed an increase of glutathione and glutathione reductase at 24 h and a sharp decrease of myo-inositol between 8 and 24 h. Phosphorylcholine increased at 8 h both in taxol and taxol plus AG957-treated cells, which was then abruptly inverted to a significantly lower concentration at 24 h, subsequently increasing again to values higher than those found in taxol-treated and control cells. All the above reported effects were lacking in cells exposed to AG957 alone. These modifications, despite the enhancement of the overall apoptotic cascade in taxol plus AG957-treated cells, can be related to the activation of cellular detoxification mechanisms, to the correct osmolarity maintenance, and to alterations of phospholipid metabolism.