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The thermal properties, emulsification, and rheological properties of exopolysaccharides (levan-BS) of Bacillus subtilisAF17 were studied and compared with those of the xanthan gum. The carbohydrate content of levan was more than 95.5% and no proteins were detected. The glass transition temperature was 31.1 °C. Levan-BS displayed a crystallization temperature of 88 °C and melting temperature was about 214 °C. Levan-BS produced more stable emulsions with olive oil and toluene, compared to xanthan gum, at an optimum concentration of 0.8%. The levan solution showed a pseudoplastic non-Newtonian fluid behavior. Levan-BS has several potential features, including high thermostability, good emulsifying properties and stability making it promising to be used in different industrial fields.

We investigated the role of heme oxygenase-1 (HO-1), a powerful anti-inflammatory and anti-oxidant enzyme, in modulating cigarette smoke (CS)-induced mucus secretion. In both rats and mice, 5-day CS exposure increased HO-1 expression and activity, mucus secretion, MUCIN 5AC (MUC5AC) gene and protein expression, and local inflammation, along with up-regulation of dual oxidase 1 gene expression and both the activity and phosphorylation of the epidermal growth factor receptor, which is involved in MUC5AC induction. Pharmacological induction of HO-1 prevented these actions and inhibition of HO-1 expression by a specific siRNA potentiated them. In French participants to the European Community Respiratory Health Survey II (n= 210, 30 to 53 years of age, 50% males) exposed to CS, a significant increase in the percentage of participants with chronic sputum was observed in those harboring at least one allele with a long (GT)nin the HO-1 promoter gene (33 repeats), which is associated with a low level of HO-1 protein expression, compared with those with a short number of (GT)n repeats (21.7% versus 8.6%, P= 0.047). No such results were observed in those who had never smoked (n= 297). We conclude that HO-1 has a significant protective effect against airway mucus hypersecretion in animals and humans exposed to CS.

ABSTRACTWe determined whether gyrAmutations were present in fluoroquinolone-resistant laboratory mutants derived from theBacteroides fragilisreference strain ATCC 25285 and in clinical isolates of B. fragilis. The two first-step mutants selected on ciprofloxacin (CIP) were devoid of gyrAmutations, whereas two of the three CIP-selected second-step mutants studied presented the same gyrAmutation leading to a Ser82Phe change. Unusual GyrA alterations, Asp81Asn or Ala118Val, were detected in two of the three first-step mutants selected on trovafloxacin (TRO), Mt3 and Mt1, respectively. The Ala118Val change had no effect on the susceptibility of Mt1 to CIP. No second-step mutant could be obtained with TRO as a selector. For the 12 clinical isolates studied, a Ser82Phe change in GyrA was found only in the 3 strains which showed the highest levels of TRO resistance (MIC, 4 μg/ml). Thus, the resistance phenotypes and genotypes observed in fluoroquinolone-resistant clinical isolates of B. fragiliswere similar to those found in CIP-selected laboratory mutants, whereas peculiar mutational events could be selected in vitro with TRO.

MICs of the new fluoroquinolone, moxifloxacin, and those of ciprofloxacin, ofloxacin and sparfloxacin for 19 genetically characterized fluoroquinolone-resistant strains were determined by the agar dilution method. The MICs of moxifloxacin for Escherichia isolates with one mutation in gyrA (corresponding to Ser83→Leu or Asp87→Gly substitution) were 0.25–0.5 mg/L, while those of ciprofloxacin, ofloxacin and sparfloxacin were 0.06–0.25, 1 and 0.12–0.5 mg/L, respectively. These values were four- to 16-fold higher than those of the same antibiotics for the wild-type strain, E. coli KL16. Similar results were observed with clinical isolates of Salmonella spp. harbouring one mutation in gyrA leading to the substitution of Ser83 by Phe or Tyr. In the presence of two mutations in the E. coligyrA gene, the MICs of moxifloxacin ciprofloxacin, ofloxacin and sparfloxacin were 2, 0.5, 4 and 1 mg/L, respectively; these were 32 times higher than the MICs of these agents for E. coli KL16. The MICs of the four quinolones for triple mutants with two mutations in gyrA and one in parC were even higher, i.e. 8, 8, 16 and 8–16 mg/L, respectively. The MICs of moxifloxacin for Campylobacter coli and Campylobacter jejuni strains with a gyrA mutation leading to Thr86→Ile substitution ranged from 1 to 2 mg/L, while the MICs of ciprofloxacin, ofloxacin and sparfloxacin were 16–32 mg/L, 8–16 and 4–8 mg/L, respectively. For high-level ciprofloxacin-resistant (MICs of 32 mg/L) clinical isolates of Enterococcus faecalis with one substitution at position 83 in GyrA (E. coli coordinates), the MICs of moxifloxacin, ofloxacin and sparfloxacin were 8–16, ≥128 and 32 mg/L respectively. In conclusion, moxifloxacin and other fluoroquinolones exhibit cross-resistance against aerobic Gram-negative bacilli and enterococci. The in-vitro activity of moxifloxacin was greater than that of ofloxacin and slightly less than that of ciprofloxacin and sparfloxacin against Enterobacteriaceae, but greater than those of the three other compounds tested against Campylobacter spp and E. faecalis.