Contribution of resistance-nodulation-division efflux pump operon smeU1-V-W-U2-X to multidrug resistance of Stenotrophomonas maltophilia.

KJ09C, a multidrug-resistant mutant of Stenotrophomonas maltophilia KJ, was generated by in vitro selection with chloramphenicol. The multidrug-resistant phenotype of KJ09C was attributed to overexpression of a resistance nodulation division (RND)-type efflux system encoded by an operon consisting of five genes: smeU1, smeV, smeW, smeU2, and smeX. Proteins encoded by smeV, smeW, and smeX were similar to the membrane fusion protein, RND transporter, and outer membrane protein, respectively, of known RND-type systems. The proteins encoded by smeU1 and smeU2 were found to belong to the family of short-chain dehydrogenases/reductases. Mutant KJ09C exhibited increased resistance to chloramphenicol, quinolones, and tetracyclines and susceptibility to aminoglycosides; susceptibility to ß-lactams and erythromycin was not affected. The expression of the smeU1-V-W-U2-X operon was regulated by the divergently transcribed LysR-type regulator gene smeRv. Overexpression of the SmeVWX pump contributed to the acquired resistance to chloramphenicol, quinolones, and tetracyclines. Inactivation of smeV and smeW completely abolished the activity of the SmeVWX pump, whereas inactivation of smeX alone decreased the activity of the SmeVWX pump. The enhanced aminoglycoside susceptibility observed in KJ09C resulted from SmeX overexpression.

Establishment of an arabinose-inducible system in Stenotrophomonas maltophilia.

A pBBad22T-derived conditioned arabinose (Ara)-inducible expression system was evaluated in Stenotrophomonas maltophilia (an opportunistic pathogen and has gained increasing attention as a cause of healthcare-associated infection). S. maltophilia cannot grow well when Ara is the sole available carbon source. The induction kinetic study, optimal inducer concentration determination, and depletion experiment were performed by using a xylE gene fusion construct, pBxylE, to monitor the expression of pBBad22T in S. maltophilia. For induction survey, the expression of catechol 2,3-dioxygenase (C23O), encoded by xylE gene, continuously increases during an 8-h induced course and can be modulated by different inducer concentrations. The applied induction condition of pBBad22T in S. maltophilia is the inducer concentration ranging from 0.1% to 0.5% for an induction time of 4 h. For repression evaluation, the C23O expression is rapidly turned off within 30 min after the removal of Ara. Accordingly, the established Ara-inducible system can provide a convenient tool for the study of S. maltophilia.

Suppression of endotoxin-induced proinflammatory responses by citrus pectin through blocking LPS signaling pathways.

Pectin is composed of complex polysaccharides rich in galactoside residues, and it is most abundant in citrus fruits. Pectin and modified pectin have been found to exhibit anti-mutagenic activity and inhibit cancer metastasis and proliferation, with no evidence of toxicity or other serious side effects. In this study, we investigated the inhibitory effect of pectin at different degrees of esterification (DEs) on the expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in lipopolysaccharide (LPS)-activated macrophages. Western blot and RT-PCR analyses demonstrated that 30% esterified pectin (DE30), DE60 pectin, and DE90 pectin significantly inhibited the protein and mRNA expressions of iNOS and COX-2 in LPS-activated macrophages, and DE90 pectin was the most-potent inhibitor. To clarify the mechanisms involved, DE90 pectin was found to inhibit the phosphorylation of MAPKs and IKK kinase activity. In addition, DE90 pectin inhibited the activation of NF-kappaB and AP-1 by electrophoretic mobility shift assay and transient transfection experiments. Finally, we found that DE90 pectin could bind with LPS, and might result in decreased binding of LPS to its receptor. These results suggest that modulation of iNOS and COX-2 expressions by dietary pectin may be important in cancer chemoprevention and anti-inflammation.

Lateral nasal wall mucoperiosteal flap: a versatile new reconstruction of the inner defect of translocated facial bone segments.

From July 1998 to December 2002, 42 patients (including 29 patients who had undergone radiation therapy) underwent a newly designed lateral nasal wall mucoperiosteal flap pedicled anteriorly on the lateral nasal artery of the angular artery to resurface a translocated facial bone segment during a facial translocation approach to the skull base to prevent its avascular necrosis. Of the 42 patients studied, 1 patient had full-thickness flap loss that resulted in bone graft necrosis. Another patient had marginal necrosis. The average length, width, and surface area of the flap was 30 mm, 45 mm, and 1350 mm measured on 5 patients. The mucoperiosteal flap tolerated radiation therapy well. The lateral nasal wall mucoperiosteal flap is a simple, reliable flap that provides ample vascularized tissue to resurface the nude translocated facial bone segment during a facial translocation approach to the skull base. It thus prevents its avascular necrosis even after radiation therapy.

Detection of Epstein-Barr virus-derived latent membrane protein-1 gene in various head and neck cancers: is it specific for nasopharyngeal carcinoma?

OBJECTIVE: The object of the study was to determine the incidence of the presence of Epstein-Barr virus-derived latent membrane protein-1 (LMP-1) gene in various head and neck cancers by polymerase chain reaction method. STUDY DESIGN: Prospective study. METHODS: During a 5-year period, polymerase chain reaction was used to investigate the presence of LMP-1 gene in various head and neck cancers from different locations and histopathological types, noncancerous nasopharyngeal biopsy samples, and tonsillectomy specimens from patients with chronic hypertrophic tonsillitis. RESULTS: Of 202 patients enrolled in the study, 53 were diagnosed by pathological study with oropharyngeal carcinoma, 45 with nasopharyngeal carcinoma, 26 with oral cavity carcinoma, 26 with laryngohypopharyngeal carcinoma, 31 with nasopharyngeal lymphoid hyperplasia, and 21 with tonsils with lymphoid hyperplasia. After the application of polymerase chain reaction, the LMP-1 gene was not detected in any sample from oral cavity carcinoma, laryngohypopharyngeal carcinoma, or nasopharyngeal lymphoid hyperplasia or from tonsillectomy specimens but was detected in only one case of tonsillar carcinoma. On the contrary, the LMP-1 gene was detected in 43 (95.6%) of 45 samples from patients with nasopharyngeal carcinoma. The statistical analysis shows a significant association (P <.001) between the presence of LMP-1 gene and tumor localization in the nasopharynx. CONCLUSIONS: The study shows that the presence of LMP-1 gene detected by polymerase chain reaction in the tumor cell is only significantly associated with tumor located in the nasopharynx, implying that Epstein-Barr virus plays a trifling role in the tumorigenesis of carcinomas arising from other head and neck locations. The polymerase chain reaction method that was used is a potential tool for screening nasopharyngeal carcinoma.