An essential saccharide binding domain for the mAb 2C7 established for Neisseria gonorrhoeae LOS by ES-MS and MSn

A study of bacterial surface oligosaccharides were investigated among different strains of Neisseria gonorrhoeae to correlate structural features essential for binding to the MAb 2C7. This epitope is widely expressed and conserved in gonococcal isolates, characteristics essential to an effective candidate vaccine antigen. Sample lipooligosaccharides (LOS), was prepared by a modification of the hot phenol-water method from which de-O-acetylated LOS and oligosaccharide (OS) components were analyzed by ES-MS-CID-MS and ES-MSnin a triple quadrupole and an ion trap mass spectrometer, respectively. Previously documented natural heterogeneity was apparent from both LOS and OS preparations which was admixed with fragments induced by hydrazine and mild acid treatment. Natural heterogeneity was limited to phosphorylation and antenni extensions to the alpha-chain. Mild acid hydrolysis to release OS also hydrolyzed the beta(1-->6) glycosidic linkage of lipid A. OS structures were determined by collisional and resonance excitation combined with MS and multistep MSn which provided sequence information from both neutral loss, and nonreducing terminal fragments. A comparison of OS structures, with earlier knowledge of MAb binding, enzyme treatment, and partial acid hydrolysis indicates a generic overlapping domain for 2C7 binding. Reoccurring structural features include a Hepalpha(1-->3)Hepbeta(1-->5)KDO trisaccharide core branched on the nonreducing terminus (Hep-2) with an alpha(1-->2) linked GlcNAc (gamma-chain), and an alpha-linked lactose (beta-chain) residue. From the central heptose (Hep-1), a beta(1-->4) linked lactose (alpha-chain), moiety is required although extensions to this residue appear unnecessary.      

L-carnitine protects gastric mucosa by decreasing ischemia-reperfusion induced lipid peroxidation.

Studies have shown that reactive oxygen metabolites and lipid peroxidation play important roles in ischemia-reperfusion injury in many organs such as heart, brain and stomach. The aim of this study is to evaluate the antioxidant effect of L-carnitine on gastric mucosal barrier, lipid peroxidation and the activities of antioxidant enzymes in rat gastric mucosa subjected to ischemia-reperfusion injury. Rats were subjected to 30 min of ischemia followed by 60 min of reperfusion. L-carnitine (100 mg/kg), was given to rats intravenously five minutes before the ischemia. In our experiment, lesion index, thiobarbituric acid reactive substances, prostaglandin E2 and mucus content in gastric tissue were measured. The results indicated that the lesion index and the formation of thiobarbituric acid reactive substances increased significantly with the ischemia-reperfusion injury in the gastric mucosa. L-carnitine treatment reduced these parameters to the values of sham operated rats. The tissue catalase and superoxide dismutase activities and prostaglandin E2 production decreased significantly in the gastric mucosa of rats exposed to ischemia-reperfusion. L-carnitine pretreatment increased the tissue catalase activity and prostaglandin E2 to the levels of sham-operated rats but did not change superoxide dismutase activity. There were no significant difference in glutathione peroxidase activity and mucus content between the groups in the gastric mucosa. In summary, L-carnitine pretreatment protected gastric mucosa from ischemia-reperfusion injury by its decreasing effect on lipid peroxidation and by preventing the decrease in prostaglandin E2 content of gastric mucosa.     

Effects of L-carnitine on neutrophil-mediated ischemia-reperfusion injury in rat stomach

Reactive oxygen metabolites play an important role in ischemia-reperfusion related gastric injury. Primary sources of reactive oxygen metabolites seem to be the xanthine/xanthine oxidase system and neutrophils accumulating within the reperfused tissue. Tissue myeloperoxidase activity is an important index of neutrophil accumulation. The purpose of the present study was to clarify the effect of L-carnitine on the accumulation of neutrophils and neutrophil-induced gastric mucosal damage in rats exposed to ischemia-reperfusion. Rats were randomly divided into three groups: sham-operated, ischemia-reperfusion and ischemia-reperfusion plus L-carnitine groups. Ischemia was induced by clamping the celiac artery for 30 min and then reperfusion was established for 60 min. Gastric injury was assessed by measuring myeloperoxidase activity in gastric tissue. The neutrophil accumulation and hemorrhagic lesions due to ischemia-reperfusion in gastric mucosa were ascertained in a histological study. L-Carnitine (100 mg kg(-1)) administrated intravenously 5 min before ischemia significantly reduced both the gastric injury and myeloperoxidase activity compared with the ischemia-reperfusion group. The results suggest that L-carnitine provides marked protection against ischemia-reperfusion-related gastric injury which could be due to its ability to reduce neutrophil accumulation in ischemic tissue.     

Effect of self-association on the structural organization of partially folded proteins: inactivated actin

The propensity to associate or aggregate is one of the characteristic properties of many nonnative proteins. The aggregation of proteins is responsible for a number of human diseases and is a significant problem in biotechnology. Despite this, little is currently known about the effect of self-association on the structural properties and conformational stability of partially folded protein molecules. G-actin is shown to form equilibrium unfolding intermediate in the vicinity of 1.5 M guanidinium chloride (GdmCl). Refolding from the GdmCl unfolded state is terminated at the stage of formation of the same intermediate state. An analogous form, known as inactivated actin, can be obtained by heat treatment, or at moderate urea concentration, or by the release of Ca(2+). In all cases actin forms specific associates comprising partially folded protein molecules. The structural properties and conformational stability of inactivated actin were studied over a wide range of protein concentrations, and it was established that the process of self-association is rather specific. We have also shown that inactivated actin, being denatured, is characterized by a relatively rigid microenvironment of aromatic residues and exhibits a considerable limitation in the internal mobility of tryptophans. This means that specific self-association can play an important structure-forming role for the partially folded protein molecules.     

Does massive proximal small bowel resection influence prostaglandin E2 synthesis in the stomach and ileum during adaptive process in rats?

It is unclear whether massive small bowel resection (SBR) affects prostaglandin E2 synthesis in the gastrointestinal tracts. Thus the aim of this study was to investigate possible changes over tissue levels of prostaglandin E2 in the stomach and ileum after massive proximal SBR. Female Swiss-Albino rats underwent control operation (groups 1, 3, 5) or an 80% SBR (groups 2, 4, 6). The specimens were obtained during relaparotomy at 3 days in groups 1 and 2, at 9 days in groups 3 and 4, at 15 days in groups 5 and 6. Group 2 vs. groups 1 and 6, group 4 vs. groups 3 and 6 had significant increase in the levels of gastric acid (P < 0.01, P < 0.05, respectively). Gastric prostaglandin E2 levels markedly increased in group 2 compared to group 1 (P < 0.01). Ileal prostaglandin E2 levels showed to be significantly higher in group 6 when compared with groups 2, 4, and 5 (P < 0.05). Gastric acidity increased at 3 and 9 days, decreased thereafter at 15 days following massive proximal SBR. While resected rats had increased levels of gastric prostaglandin E2 at 3 days, ileal prostaglandin E2 was markedly elevated at 15 days. Therefore, we conclude that prostaglandin E2 may have a possible role in regulating intestinal adaptation at the end of the adaptive process, and contribute to cytoprotective barrier function in the ileum and stomach at early and late periods of the intestinal adaptation, respectively.