Novel Nicotinic Acetylcholine Receptor Ligands based on Cytisine, Ferruginine, Anatoxin-a and Choline : <i>In vitro </i>Evaluation and Structure-Activity Relationships

Nicotinic acetylcholine receptors (nAChRs), excitatory ligand-gated cation channels, are transmembranic allosteric proteins composed of five polypeptide chains. The subtype at the neuromuscular junction consists of α1, β1, γ and δ subunits whereas the neuronal subtypes are formed by a combination of different α (α2 to α10) and β(β2 to β4) subunits (heteromeric type) or identical α subunits (homomeric type). NAChRs are widely distributed in the central nervous system and in the periphery. In recent years, there has been increasing interest in nAChR ligands as potential analgesics and therapeutics for the treatment of various neurological and mental disorders related to a decrease in cholinergic function such as Alzheimer’s and Parkinson’s diseases, attention deficit/hyperactivity disorder, schizophrenia, and depression. Natural toxic alkaloids like (-)-cytisine, (+)-ferruginine, and (+)-anatoxin-a possess high affinity for α4β2 nAChR, representing the major population of nACh receptors in mammalian brain, but no appropriate selectivity. Structure-activity relationship studies for these ligands are missing for other subtypes, like α7, α3β4 and (α1)2β1γδ. In order to evaluate the affinities of novel analogues of (-)-cytisine, (+)-ferruginine, and (+)-anatoxin-a, in vitro radioligand binding studies were performed for four different nAChR subtypes: α4β2*, α7*, α3β4* and (α1)2β1γδ nAChRs, using membranes of native tissues (rat brains, calf/pig adrenals and Torpedo calif. electroplax). Important information could be obtained concerning the structural requirements that enhance selectivity of these novel analogues for α4β2* nAChR over other nAChRs investigated. In general, since the molecular recognition between ligands and nAChRs might be based on cation-pi interactions and a hydrogen bond formation between the receptor site and the ligand (HBD-HBA interaction), all high affinity compounds bear the cationic and HBA motifs. Beside the search and development of novel nAChR ligands exhibiting selectivity for the α4β2* nAChR, interest is growing to develop novel compounds selective for the α7 and α3-containing subtypes. Choline has proved to be a selective ligand for the α7, showing also neuroprotective actions. In this study, choline derivatives are evaluated in in vitro radioligand binding studies to gain more information about the structural requirements to enhance the selectivity for α7* versus the α4β2* nicotinic receptor

Anti-Biofilm Activity of a Long-Chain Fatty Aldehyde from Antarctic Pseudoalteromonas haloplanktis TAC125 against Staphylococcus epidermidis Biofilm

Staphylococcus epidermidis is a harmless human skin colonizer responsible for ~20% of orthopedic device-related infections due to its capability to form biofilm. Nowadays there is an interest in the development of anti-biofilm molecules. Marine bacteria represent a still underexploited source of biodiversity able to synthesize a broad range of bioactive compounds, including anti-biofilm molecules. Previous results have demonstrated that the culture supernatant of Antarctic marine bacterium Pseudoalteromonas haloplanktis TAC125 impairs the formation of S. epidermidis biofilm. Further, evidence supports the hydrophobic nature of the active molecule, which has been suggested to act as a signal molecule. In this paper we describe an efficient activity-guided purification protocol which allowed us to purify this anti-biofilm molecule and structurally characterize it by NMR and mass spectrometry analyses. Our results demonstrate that the anti-biofilm molecule is pentadecanal, a long-chain fatty aldehyde, whose anti-S. epidermidis biofilm activity has been assessed using both static and dynamic biofilm assays. The specificity of its action on S. epidermidis biofilm has been demonstrated by testing chemical analogs of pentadecanal differing either in the length of the aliphatic chain or in their functional group properties. Further, indications of the mode of action of pentadecanal have been collected by studying the bioluminescence of a Vibrio harveyi reporter strain for the detection of autoinducer AI-2 like activities. The data collected suggest that pentadecanal acts as an AI-2 signal. Moreover, the aldehyde metabolic role and synthesis in the Antarctic source strain has been investigated. To the best of our knowledge, this is the first report on the identification of an anti-biofilm molecule form from cold-adapted bacteria and on the action of a long-chain fatty aldehyde acting as an anti-biofilm molecule against S. epidermidis

Colonic epithelial ion transport is not affected in patients with diverticulosis

<p>Abstract</p> <p>Background</p> <p>Colonic diverticular disease is a bothersome condition with an unresolved pathogenesis. It is unknown whether a neuroepithelial dysfunction is present. The aim of the study was two-fold; (1) to investigate colonic epithelial ion transport in patients with diverticulosis and (2) to adapt a miniaturized Modified Ussing Air-Suction (MUAS) chamber for colonic endoscopic biopsies.</p> <p>Methods</p> <p>Biopsies were obtained from the sigmoid part of the colon. 86 patients were included. All patients were referred for colonoscopy on suspicion of neoplasia and they were without pathological findings at colonoscopy (controls) except for diverticulosis in 22 (D-patients). Biopsies were mounted in MUAS chambers with an exposed area of 5 mm². Electrical responses to various stimulators and inhibitors of ion transport were investigated together with histological examination. The MUAS chamber was easy to use and reproducible data were obtained.</p> <p>Results</p> <p>Median basal short circuit current (SCC) was 43.8 μA·cm^-2(0.8 – 199) for controls and 59.3 μA·cm^-2(3.0 – 177.2) for D-patients. Slope conductance was 77.0 mS·cm^-2(18.6 – 204.0) equal to 13 Ω·cm²for controls and 96.6 mS·cm^-2(8.4 – 191.4) equal to 10.3 Ω·cm²for D-patients. Stimulation with serotonin, theophylline, forskolin and carbachol induced increases in SCC in a range of 4.9 – 18.6 μA·cm^-2, while inhibition with indomethacin, bumetanide, ouabain and amiloride decreased SCC in a range of 6.5 – 27.4 μA·cm^-2, and all with no significant differences between controls and D-patients. Histological examinations showed intact epithelium and lamina propria before and after mounting for both types of patients.</p> <p>Conclusion</p> <p>We conclude that epithelial ion transport is not significantly altered in patients with diverticulosis and that the MUAS chamber can be adapted for studies of human colonic endoscopic biopsies.</p

Secukinumab efficacy in the treatment of nail psoriasis: a case series

Nail involvement is frequent in patients with psoriasis, especially those with psoriatic arthritis (PsA), and can significantly impair quality of life (QoL). It is typically difficult to treat compared with skin lesions, although several conventional treatment options are available. The aim of this article is to describe our experience in the treatment of nail psoriasis with secukinumab in a case series. Fifteen patients (11 males and 4 females), with moderate-severe plaque psoriasis and nail psoriasis, eligible for systemic therapy, and received secukinumab. The Psoriasis Area and Severity Index (PASI) and body surface area (BSA) assessed cutaneous severity. Nail Psoriasis Severity Index (NAPSI) was used to evaluate nail involvement. Starting from 6 weeks after initiation of treatment with secukinumab 300 mg, a clinically significant response was observed, with progressive reduction of both skin and nail disease indexes. Average reduction of PASI was 75%, of BSA 70%, and of NAPSI 50%, at week 6. At week 12, NAPSI reduction was by 80%, of PASI 90%, and of BSA 97%. Effective treatment of both skin and nail psoriasis was obtained with secukinumab, a new approach to psoriatic patients resistant to topical therapy

Anti-biofilm activity of Pseudoalteromonas haloplanktis TAC125 against Staphylococcus epidermidis biofilm: Evidence of a signal molecule involvement?

Staphylococcus epidermidis is recognized as cause of biofilm-associated infections and interest in the development of new approaches for S. epidermidis biofilm treatment has increased. In a previous paper we reported that the supernatant of Antarctic bacterium Pseudoalteromonas haloplanktis TAC125 presents an anti-biofilm activity against S. epidermidis and preliminary physico-chemical characterization of the supernatant suggested that this activity is due to a polysaccharide. In this work we further investigated the chemical nature of the anti-biofilm P. haloplanktis TAC125 molecule. The production of the molecule was evaluated in different conditions, and reported data demonstrated that it is produced in all P. haloplanktis TAC125 biofilm growth stages, also in minimal medium and at different temperatures. By using a surface coating assay, the surfactant nature of the anti-biofilm compound was excluded. Moreover, a purification procedure was set up and the analysis of an enriched fraction demonstrated that the anti-biofilm activity is not due to a polysaccharide molecule but that it is due to small hydrophobic molecules that likely work as signal. The enriched fraction was also used to evaluate the effect on S. epidermidis biofilm formation in dynamic condition by BioFlux system