Structural determination of the sheath-forming polysaccharide of Sphaerotilus montanus using thiopeptidoglycan lyase which recognizes the 1,4 linkage between α-d-GalN and ß-d-GlcA.

Sphaerotilus natans is a filamentous sheath-forming bacterium commonly found in activated sludge. Its sheath is assembled from a thiolic glycoconjugate called thiopeptidoglycan. S. montanus ATCC-BAA-2725 is a sheath-forming member of stream biofilms, and its sheath is morphologically similar to that of S. natans. However, it exhibits heat susceptibility, which distinguishes it from the S. natans sheath. In this study, chemical composition and solid-state NMR analyses suggest that the S. montanus sheath is free of cysteine, indicating that disulfide linkage is not mandatory for sheath formation. The S. montanus sheath was successfully solubilized by N-acetylation, allowing solution-state NMR analysis to determine the sugar sequence. The sheath was susceptible to thiopeptidoglycan lyase prepared from the thiopeptidoglycan-assimilating bacterium, Paenibacillus koleovorans. The reducing ends of the enzymatic digests were labeled with 4-aminobenzoic acid ethyl ester, followed by HPLC. Two derivatives were detected, and their structures were determined. We found that the sheath has no peptides and is assembled as follows: [→4)-ß-d-GlcA-(1→4)-ß-d-Glc-(1→3)-ß-d-GalNAc-(1→4)-α-d-GalNAc-(1→4)-α-d-GalN-(1→]n (ß-d-Glc and α-d-GalNAc are stoichiometrically and substoichiometrically 3-O-acetylated, respectively). Thiopeptidoglycan lyase was thus confirmed to cleave the 1,4 linkage between α-d-GalN and ß-d-GlcA, regardless of the peptide moiety. Furthermore, vital fluorescent staining of the sheath demonstrated that elongation takes place at the tips, as with the S. natans sheath.

Development of prediction models for the sensitivity of oral squamous cell carcinomas to preoperative S-1 administration.

S-1 is an anticancer agent that is comprised of tegafur, gimeracil, and oteracil potassium, and is widely used in various carcinomas including oral squamous cell carcinoma (OSCC). Although an established prediction tool is not available, we aimed to develop prediction models for the sensitivity of primary OSCC cases to the preoperative administration of S-1. We performed DNA microarray analysis of 95 cases with OSCC. Using global gene expression data and the clinical data, we developed two different prediction models, namely, model 1 that comprised the complete response (CR) + the partial response (PR) versus stable disease (SD) + progressive disease (PD), and model 2 that comprised responders versus non-responders. Twelve and 18 genes were designated as feature genes (FGs) in models 1 and 2, respectively, and, of these, six genes were common to both models. The sensitivity was 96.3%, the specificity was 91.2%, and the accuracy was 92.6% for model 1, and the sensitivity was 95.6%, the specificity was 85.2%, and the accuracy was 92.6% for model 2. These models were validated using receiver operating characteristic analysis, and the areas under the curves were 0.967 and 0.949 in models 1 and 2, respectively. The data led to the development of models that can reliably predict the sensitivity of patients with OSCC to the preoperative administration of S-1. The mechanism that regulates S-1 sensitivity remains unclear; however, the prediction models developed provide hope that further functional investigations into the FGs will lead to a greater understanding of drug resistance.

Efficacy and safety of repaglinide vs nateglinide for treatment of Japanese patients with type 2 diabetes mellitus.

UNLABELLED: Aims/Introduction: Repaglinide is a short-acting insulin secretagogue. We assessed the efficacy and safety of repaglinide in comparison with nateglinide in Japanese patients with type 2 diabetes previously treated with diet and exercise. MATERIALS AND METHODS: In this 16-week randomized, multicenter, double-blind, parallel-group, active-controlled superiority trial, Japanese patients with type 2 diabetes and glycated hemoglobin (HbA1c) of ≥6.9 and ≤9.4% were enrolled. Patients were randomly assigned to receive 0.5 mg repaglinide (n = 64) or 90 mg nateglinide (n = 66) three times a day. The primary end-point was changes in HbA1c from baseline to the end of treatment. RESULTS: Mean reductions of HbA1c were significantly greater for the repaglinide group than the nateglinide group (-1.17 ± 0.62 vs -0.81 ± 0.39%, P < 0.001). The target HbA1c values of <6.9% were achieved by 75.0% of the repaglinide group vs 59.1% for nateglinide. Mean changes in fasting plasma glucose also showed significantly greater efficacy for repaglinide than nateglinide (-26.0 ± 20.9 vs -18.3 ± 17.8 mg/dL, P < 0.001). There were no differences in the adverse event rates between the repaglinide and the nateglinide group, by 57.8% (37/64) and 60.6% (40/66), respectively. Incidences of hypoglycemic symptoms were 17.2% (11/64, 28 events) in the repaglinide group and 6.1% (4/66, 20 events) in the nateglinide group, respectively. CONCLUSIONS: In type 2 diabetic patients treated with diet and exercise, repaglinide monotherapy gives greater glycemic improvement than nateglinide monotherapy in reducing HbA1c and fasting plasma glucose values after 16 weeks. This trial was registered with JapicCTI (no. JapicCTI-080521). (J Diabetes Invest, doi: 10.1111/j.2040-1124.2011.00188.x, 2011).