Polyclonal antibodies have been raised against the alpha, beta and gamma subunits of the amiloride-sensitive Na+ channel. The three subunits were detected by immunohistochemistry at the apical membrane of epithelial cells from the distal colon, the lung and the distal segments of the kidney tubules. No significant labelling was detected in lung alveoli, suggesting that it is not a major site of expression of the Na+ channel. Effects of a low Na+ diet or of dexamethasone treatment were measured at the mRNA level and at the protein level by immunohistochemistry. In the colon, steroids controlled Na+ channel activity via the stimulation of the transcription of beta and gamma subunits. The alpha mRNA was constitutively expressed. However, while neither alpha, beta nor gamma proteins were detected in the colon of control animals, they were all detected in the colon of steroid-treated animals. In the lung, Na+ channel expression was regulated by glucocorticoids the circulating level of which was sufficiently high to induce a maximal expression of the three subunits, even in control animals. Adrenalectomy drastically reduced expression of the three subunits. A surprising finding was the apparent absence of steroid effects on alpha, beta and gamma subunit expression in the kidney. Neither the expression of the mRNAs nor the expression of the proteins were significantly altered by aldosterone or by dexamethasone. These results could be due to mixed gluco- and mineralocorticoid regulations in different segments of the kidney tubule, but their interpretation also requires regulations that are apparently not found in the lung or colon.

Biofilms formed by pathogenic bacteria and fungi are associated with a wide range of diseases, from device-related infections (such as catheters or prosthetic joints) to chronic infections occurring on native tissues (such as lung infections in cystic fibrosis patients). Biofilms are therefore responsible for an important medical and economic burden. Currently used antibiotics have mostly been developed to target exponentially growing microorganisms and are poorly effective against biofilms. In particular, even high concentrations of bactericidal antibiotics are inactive against a subset of persistent biofilm bacteria, which can cause infection recurrence despite prolonged treatments. While the search for a magic bullet antibiotic effective against both planktonic and biofilm bacteria is still active, alternative preventive and curative approaches are currently being developed either limiting adhesion or biofilm formation or targeting biofilm tolerance by killing persister bacteria. Most of these approaches are adjunctive using new molecules in combination with antibiotics. This review presents promising approaches or strategies that could improve our ability to prevent or eradicate bacterial biofilms in medical settings.

␥-aminobutyric acid type A (GABA A ) receptors comprise a subfamily of ligand-gated ion channels whose activity can be modulated by ligands acting at the benzodiazepine binding site on the receptor. The benzodiazepine binding site was characterized using a site-directed mutagenesis strategy in which amino acids of the ␣ 5 subunit were substituted by their corresponding ␣ 1 residues. Given the high affinity and selectivity of ␣ 1 -containing compared with ␣ 5 -containing GABA A receptors for zolpidem, mutated ␣ 5 subunits were co-expressed with ␤ 2 and ␥ 2 subunits, and the affinity of recombinant receptors for zolpidem was measured. One ␣ 5 mutant (bearing P162T, E200G, and T204S) exhibited properties similar to that of the ␣ 1 subunit, notably high affinity zolpidem binding and potentiation by zolpidem of GABA-induced chloride current. Two of these mutations, ␣ 5 P162T and ␣ 5 E200G, might alter binding pocket conformation, whereas ␣ 5 T204S probably permits formation of a hydrogen bond with a proton acceptor in zolpidem. These three amino acid substitutions also influenced receptor affinity for CL218872. Our data thus suggest that corresponding amino acids of the ␣ 1 subunit, particularly ␣ 1 -Ser 204, are the crucial residues influencing ligand selectivity at the binding pocket of ␣ 1 -containing receptors, and a model of this binding pocket is presented.

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Despite the availability of antibiotics and vaccines, Neisseria meningitidis remains a major cause of meningitis and sepsis in humans. Due to its extracellular lifestyle, bacterial adhesion to host cells constitutes an attractive therapeutic target. Here, we present a high-throughput microscopy-based approach that allowed the identification of compounds able to decrease type IV pilus-mediated interaction of bacteria with endothelial cells in the absence of bacterial or host cell toxicity. Compounds specifically inhibit the PilF ATPase enzymatic activity that powers type IV pilus extension but remain inefficient on the ATPase that promotes pilus retraction, thus leading to rapid pilus disappearance from the bacterial surface and loss of pili-mediated functions. Structure activity relationship of the most active compound identifies specific moieties required for the activity of this compound and highlights its specificity. This study therefore provides compounds targeting pilus biogenesis, thereby inhibiting bacterial adhesion, and paves the way for a novel therapeutic option for meningococcal infections. meningitis | bacteria | virulence | inhibitors | type IV pilus