Regional differences in the modulatory role of the epithelium in sheep airway.

1. The airway epithelium may modulate smooth muscle responsiveness via the release of biologically active substances, such as nitric oxide (NO) and prostaglandins. Based on regional differences in structure and function described for the airway epithelium, we performed a comparative study on the responsiveness of sheep isolated, epithelium-intact or -denuded, first- to fourth-order bronchi to acetylcholine (ACh). 2. We performed contractility studies using KCl or cholinergic stimuli in the presence or absence of NO or prostaglandin-related drugs in epithelium-intact and epithelium-denuded bronchial strips obtained from all four airway regions. We also studied the expression of NO synthase (NOS), using the NADPH-diaphorase staining technique, and the effect of airway epithelium removal on the synthesis of NO metabolites in the different bronchi orders. 3. There was no difference in the response of first- to fourth-order epithelium-intact bronchi to ACh (1 nmol/L-100 mmol/L) or KCl (5-100 mmol/L). Removal of the epithelium had no effect on ACh-induced contractions of first- and second-order bronchi, but increased responses of third- and fourth-order bronchi to ACh. The NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (100 micromol/L) increased ACh-induced contractions of fourth-order epithelium-intact bronchi only. The NO donor sodium nitroprusside (1 nmol/L-1 mmol/L) equally relaxed 1 micromol/L carbachol-precontracted epithelium-denuded first- and fourth-order bronchi. 4. Although NAPDH-diaphorase staining demonstrated no regional differences in NOS expression, basal levels of NO metabolites were 4.5-fold greater in fourth- compared with second-order epithelium-intact bronchi. 5. The cyclo-oxygenase inhibitor indomethacin (10 micromol/L) had no effect on ACh-induced contractions of first- to fourth-order epithelium-intact bronchi, but decreased responses of fourth-order epithelium-denuded bronchi to ACh. The contractile effect of the thromboxane A(2) mimetic U-46619 (1 nmol/L-10 micromol/L) was greater in fourth- compared with first-order epithelium-denuded bronchi. 6. In conclusion, the sheep airway epithelium exhibits regional differences in its modulatory role and this is particularly apparent in small bronchi.

Reduced susceptibility to quinupristin/dalfopristin in Enterococcus faecium in Greece without prior exposure to the agent.

During 2005-2006, a total of 865 Enterococcus faecium isolated from patients from eight Greek hospitals were tested for susceptibility to quinupristin/dalfopristin (Q/D). Among them, 250 genetically unrelated strains (28.9%) were found to be intermediate-resistant to Q/D (minimum inhibitory concentration (MIC) 1.5-4 mg/L); all were resistant to dalfopristin (MIC=16-64 mg/L), whilst 69% were resistant to quinupristin, carrying the ermB gene. No strain was found to carry any of the known genes, such as vatE and vatD, involved in Q/D resistance, indicating that a non-transferable undetermined mechanism is responsible for the expression of low-level Q/D resistance. The high percentage of Q/D-intermediate-resistant E. faecium in Greece was not associated with prior consumption of the agent or with the veterinary use of virginiamycin.