Nasal airway changes after Le Fort I--impaction and advancement: anatomical and functional findings.

Twenty patients were studied prospectively to assess intranasal anatomical changes and functional changes resulting from a one-piece Le Fort I-osteotomy with anterior and superior positioning of the maxilla. Presurgical and 3 months postsurgical rhinological inspection, anterior rhinomanometry and acoustic rhinometry were performed. Interalar width was measured and cephalograms were used to assess maxillary movement. Rhinoscopically, three septal perforations (15%) were noticed. Turbinate enlargement was less common postoperatively. Interalar width increased significantly. These findings correlate with a significant increase in cross-sectional diameter at the Isthmus nasi revealed by acoustic rhinometry 3 months postoperatively. The mean total nasal airflow measured by anterior rhinomanometry was unchanged indicating no increase in resistance despite decreased intranasal dimensions in cases where the impaction is not higher than 5 mm.

Pathways of mucin O-glycosylation in normal and malignant rat colonic epithelial cells reveal a mechanism for cancer-associated Sialyl-Tn antigen expression.

The Sialyl-Tn antigen (Sialyl alpha-Ser/Thr) is expressed as a cancer-associated antigen on the surface of cancer cells. Its presence is associated with a poor prognosis in patients with colorectal and other cancers. We previously reported that Sialyl-Tn expression in LSC human colon cancer cells could be explained by a specific lack of the activity of core 1 beta3-Gal-transferase (Brockhausen et al., Glycoconjugate J. 15, 595-603, 1998) and an inability to synthesize the common O-glycan core structures. To support this mechanism, or find other mechanisms to explain Sialyl-Tn antigen expression, we investigated the O-glycosylation pathways in clonal rat colon cancer cell lines that were selected for positive or negative expression of Sialyl-Tn antigen, and compared these pathways to those in normal rat colonic mucosa. Normal rat colonic mucosa had very active glycosyltransferases synthesizing O-glycan core structures 1 to 4. Several sialyl-, sulfo- and fucosyltransferases were also active. An M type core 2 beta6-GlcNAc-transferase was found to be present in rat colon mucosa and all of the rat colon cancer cells. O-glycosylation pathways in rat colon cancer cells were significantly different from normal rat colonic mucosa; for example, rat colon cancer cells lost the ability to synthesize O-glycan core 3. All rat colon cancer cell lines, regardless of the Sialyl-Tn phenotype, expressed glycosyltransferases assembling complex O-glycans of core 1 and core 2 structures (unlike human LSC colon cancer cells which lack core 1 beta3-Gal-transferase activity). It was the activity of CMP-sialic acid:GalNAc-mucin alpha6-sialyltransferase that coincided with Sialyl-Tn expression. Sialyl-Tn negative cells had a several fold higher activity of core 2 beta6-GlcNAc-transferase which synthesizes complex O-glycans that may mask adjacent Sialyl-Tn epitopes. The results suggest a new mechanism controlling Sialyl-Tn expression in cancer cells.