ABSTRACT
Objective To investigate the molecular size distribution and the structure of group B me-ningococcal capsular polysaccharides for the development of vaccines .Methods The molecular size distribution of group B meningococcal capsular polysaccharides was analyzed by chromatography on a Sepharose CL -4B col-umn.The molecular weight of repeat units were measured by matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS).The structural characteristics of group B meningococcal capsular polysaccharides were analyzed by nuclear magnetic resonance ( NMR) based on the chemical shift of all charac-teristic protons by using group C meningococcal capsular polysaccharides and sialic acid as the controls .Results The KD value of group B meningococcal capsular polysaccharides extracted from 15 strains were ranged from 0.60 to 0.76.The molecular weight of repeat units was 284, which was identical to the theoretical value .The group B meningococcal capsular polysaccharides were 2→8 linked homopolymers of sialic acid lacking O-acetyl groups.Conclusion The group B meningococcal capsular polysaccharides had lower molecular weights , which might result in their poor immunogenicity .The structure of group B meningococcal capsular polysaccharides could be quickly and accurately analyzed by NMR technology .
ABSTRACT
Objective: To investigate changes in species and amounts of intestinal flora after reconstruction of upper digestive tract, and the relationship with the infective complications.Methods: 52 patients with advanced malignancy being performed reconstruction of upper gastrointestinal tract was prospectively observed .The species of bacteria and counts of the colony forming units(CFU) were measured from juice taking from the upper jejunum through nasointestinal tube during operation, the second day and the fifth day after operation. Meanwhile, the plasma endotoxin concentration was determined with the modified chromogenic limulus assay.Results: There weren't significant changes of intestinal flora in species and amounts between groups (P＞0.05.) No any signs of bacterial translocation were seen. There was no significant difference for the level of plasma endotoxin between groups.Conclusion: There is no disorder of intestinal flora and bacterial translocation during the perioperative period after upper digestive tract reconstruction successfully.