Radiological localization of Schneiderian papilloma.

BACKGROUND: It has been recently reported that the site of attachment of Schneiderian papillomas can be predicted with high accuracy on preoperative computed tomography (CT) scans using bony osteitic changes as an indicator. The objective of this study is to evaluate, in a blinded fashion, the reliability of the osteitis sign at predicting the site of attachment of Schneiderian papillomas. METHODS: A retrospective cohort study of patients who underwent endoscopic surgical resection for inverted papilloma (IP) or cylindrical papilloma between September 2002 and September 2009 in a tertiary care rhinology center was carried out. The preoperative sinus CT scans were collected and reviewed by a fellowship-trained and experienced head and neck radiologist who was blinded to the intraoperative findings. The radiologist attempted to identify and grade bony osteitic changes in the sinuses. The radiological findings were then correlated with the actual site of attachment reported by the surgeon in the operative report. RESULTS: A total of 34 patients were evaluated. Six (18%) patients had a single site of osteitis and 28 (82%) were found to have multiple sites of osteitis. The sensitivity and specificity of the radiological prediction based on the degree of osteitis was found to be 74% (46.5-90.3%) and 0% (0-17%), respectively. The predictive value of the radiological localization was 41%. CONCLUSION: Osteitic changes are very common nonspecific findings on CT scans of patients with Schneiderian papillomas. Their presence as well as the degree of osteitis did not allow preoperative localization of tumor attachment.

Characterization of a beta-N-acetylhexosaminidase and a beta-N-acetylglucosaminidase/beta-glucosidase from Cellulomonas fimi.

The gram-positive soil bacterium Cellulomonas fimi is shown to produce at least two intracellular beta-N-acetylglucosaminidases, a family 20 beta-N-acetylhexosaminidase (Hex20), and a novel family 3-beta-N-acetylglucosaminidase/beta-glucosidase (Nag3), through screening of a genomic expression library, cloning of genes and analysis of their sequences. Nag3 exhibits broad substrate specificity for substituents at the C2 position of the glycone: kcat/Km values at 25 degrees C were 0.066 s(-1) x mM(-1) and 0.076 s(-1) x mM(-1) for 4'-nitrophenyl beta-N-acetyl-D-glucosaminide and 4'-nitrophenyl beta-D-glucoside, respectively. The first glycosidase with this broad specificity to be described, Nag3, suggests an interesting evolutionary link between beta-N-acetylglucosaminidases and beta-glucosidases of family 3. Reaction by a double-displacement mechanism was confirmed for Nag3 through the identification of a glycosyl-enzyme species trapped with the slow substrate 2',4'-dinitrophenyl 2-deoxy-2-fluoro-beta-D-glucopyranoside. Hex20 requires the acetamido group at C2 of the substrate, being unable to cleave beta-glucosides, since its mechanism involves an oxazolinium ion intermediate. However, it is broad in its specificity for the D-glucosyl/D-galactosyl configuration of the glycone: Km and kcat values were 53 microM and 482.3 s(-1) for 4'-nitrophenyl beta-N-acetyl-D-glucosaminide and 66 microM and 129.1 s(-1) for 4'-nitrophenyl beta-N-acetyl-D-galactosaminide.