Activities of polysaccharides obtained fromGrifola frondosa on insulin-dependent diabetes mellitus induced by streptozotocin in mice

In an experiment with C57BL/6J model mice having insulin-dependent diabetes mellitus (IDDM) induced by streptozotocin, the glucans obtained from Maitake fruit-body were found to suppress activation and proliferation of macrophages and consequently to inhibit the generation of nitric oxide (NO) and IL (interleukin)-1 β, which are β-cell destruction factors, suppressing their production to 0.17 and 0.33, respectively, relative to the control mice. In addition, the glucans caused proliferation and activation of B cells, as detected by flow cytometric analysis of whole spleen cell lymphocytes. Cytokine secretion from whole spleen cells was also investigated by ELISA, which showed that IFN-γ production was suppressed while IL-4 production increased. These glucans, acting in the diabetic mice, accelerate recovery of Th2 cell functions, regulate the balance between Th1 cells and Th2 cells, and consequently repress the cytotoxic reaction. In spite of the effect of the glucans on the immune reactions, IDDM itself does not show any favorable signs of recovery. For the result, some other factors are suggested to be acting in the complex immunity network in relation to IDDM generation.     

Immunochemical studies on the capsular polysaccharides of pneumococcal type IX

1. In addition to the previously identified components, d-glucose, N-acetyl-d-glucosamine and d-glucuronic acid, the immunologically specific capsular polysaccharide of pneumococcal type IX (polysaccharide S IX) is now found to contain mannosamine and galactosamine, probably as their N-acetyl derivatives. 2. Partial hydrolysis yields a complex mixture of oligosaccharides, several of which have been separated. 3. One of these is alpha-d-glucuronopyranosyl-(1-->3)-d-glucose. It is an inhibitor of the precipitation of antipneumococcal type IX serum by polysaccharide S IX. 4. Two others, d-glucuronopyranosyl-(1-->3)-d-glucosamine and d-glucuronopyranosyl-(1-->3)-d-galactosamine have been identified and a trisaccharide and pentasaccharide partially characterized.     

罗汉果多糖对环磷酰胺所致的免疫 抑制小鼠免疫功能的影响

该研究将小鼠随机分成正常组,模型组,罗汉果多糖低、中、高剂量组(25、50、100 mg·kg~(-1))和左旋咪唑组,采用腹腔注射环磷酰胺(20 mg·kg~(-1))建立免疫抑制小鼠模型,连续灌胃给药14 d后,测定各组小鼠的免疫器官指数、廓清指数(K)、吞噬指数(α)、T和B淋巴细胞增殖水平、耳肿胀度、半数溶血值(HC50)以及免疫球蛋白G(IgG)、免疫球蛋白M(IgM)、IL-2、IL-4、IL-6、TNF-α的含量,并观察脾组织病理形态变化,考察罗汉果多糖对免疫抑制小鼠免疫功能的影响。结果表明:罗汉果多糖各剂量组(25、50、100 mg·kg~(-1))均能显著提高免疫抑制小鼠的免疫器官指数、半数溶血值(HC_(50))、B淋巴细胞增殖能力,明显降低耳肿胀度,显著增加IgG、IgM、IL-2、IL-4、IL-6、TNF-α的含量。罗汉果多糖中、高剂量组(50、100 mg·kg~(-1))能显著增强T淋巴细胞增殖能力,明显增加廓清指数(K)、吞噬指数(α)。脾组织病理学观察结果表明,罗汉果多糖可以减轻免疫抑制小鼠脾脏的病理损伤。这表明罗汉果多糖能明显增强环磷酰胺所致免疫抑制小鼠的免疫功能。     

Base hydrolysis of phosphodiester bonds in pneumococcal polysaccharides

A comprehensive study of the base hydrolysis of all phosphodiester bond-containing capsular polysaccharides of the 23-valent pneumococcal vaccine is described here. Capsular polysaccharides from serotypes 6B, 10A, 17F, 19A, 19F, and 20 contain a phosphodiester bond that connects the repeating units in these polysaccharides (also referred to as backbone phosphodiester bonds), and polysaccharides from serotypes 11A, 15B, 18C, and 23F contain a phosphodiester bond that links a side chain to their repeating units. Molecular weight measurements of the polysaccharides, using high performance size exclusion chromatography with tandem multiangle laser light scattering and refractive index detection, was used to evaluate the kinetics of hydrolysis. The measurement of molecular weight provides a high degree of sensitivity in the case of small extents of reaction, thus allowing reliable measurements of the kinetics over short times. Pseudo-first-order rate constants for these polysaccharides were estimated using a simple model that accounts for the polydispersity of the starting sample. It was found that the relative order of backbone phosphodiester bond instability due to base hydrolysis was 19A > 10A > 19F > 6B > 17F, 20. Degradation of side-chain phosphodiester bonds was not observed, although the high degree of sensitivity in measurements is lost in this case, due to the low contribution of the side chains to the total polysaccharide molecular weight. In comparison with literature data on pneumococcal polysaccharide 6A, 19A was found to be the more labile, and hence appears to be the most labile pneumococcal polysaccharide studied to date. The rate of hydrolysis increased at higher pH and in the presence of divalent cation, but the extent was lower than expected based on similar data on RNA. Finally, the differences in the phosphodiester bond stabilities were analyzed by considering stereochemical factors in these polysaccharides. These results also provide a framework for evaluation of molecular integrity of phosphodiester-bond-containing polysaccharides in different solution conditions.