Comparison of several mathematical models for describing the joint effect of temperature and ph on glucanex activity

The aim of the present work was to evaluate with different statistical criteria the suitability of nine equations for describing and optimizing the simultaneous effect of temperature and pH on glucanex activity using two characteristic polysaccharides (curdlan and laminarin) as substrates. The most satisfactory solutions were found with an empirical equation constituted with parameters of practical interest (Rosso model), and a hybrid model between the Arrhenius equation and the mathematical expression generated by the protonation-hydroxylation mechanism (Tijskens model). The joint optimal values of pH and temperature calculated with the Rosso model were obtained at 4.64 and 50°C with curdlan and 4.64 and 48°C using laminarin as substrate.     

Strong association between mRNA folding strength and protein abundance in S. cerevisiae

One of the open questions in regulatory genomics is how the efficiency of gene translation is encoded in the coding sequence. Here we analyse recently generated measurements of folding energy in Saccharomyces cerevisiae, showing that genes with high protein abundance tend to have strong mRNA folding (mF; R=0.68). mF strength also strongly correlates with ribosomal density and mRNA levels, suggesting that this relation at least partially pertains to the efficiency of translation elongation, presumably by preventing aggregation of mRNA molecules.     

牛膝多糖对哮喘大鼠信号转导子和转录激活子6表达的影响

目的：研究牛膝多糖（ABPS）对支气管哮喘大鼠支气管信号转导子和转录激活子6（STAT6）及其mRNA表达的影响。方法：雄性SD大鼠30只随机分为正常对照组、哮喘组和哮喘＋牛膝多糖组（ABPS组）。留取支气管肺泡灌洗液（BALF）进行细胞总数、嗜酸性粒细胞（E0s）和分类计数;并测定BALF和血清中白细胞介素4（IL-4）浓度;采用免疫组化法和原位杂交法分别检测STAT6蛋白和STAT6 mRNA的表达。结果：①哮喘组BALF中细胞总数、EOS绝对值和EOS占细胞总数的百分比（EOS％）均高于对照组（P〈0．01）,ABPS组上述指标均低于哮喘组（P〈0．01）;②BALF和血清中IL-4浓度哮喘组均高于对照组（均为P〈0.01）,ABPs组均低于哮喘组（均为P〈0．01）;③免疫组化和原位杂交显示,哮喘组支气管STAT6蛋白和STAT6 mRNA表达的平均吸光度（LD）均高于对照组,ABPS组则均低于哮喘组（均为P〈0．01）,其主要表达细胞是上皮细胞。结论：哮喘大鼠支气管STAT6及其mRNA较强表达,上皮细胞是其主要表达细胞;牛膝多糖有抑制哮喘气道EOS性炎症的作用．下调STAT6及其mRNA表达,使IL-4合成减少可能为其重要作用机制。     

Receptor expression and oxidase activity in human neutrophils: Regulation by granulocyte-macrophage colony-stimulating factor and dependence upon protein biosynthesis

Incubation of human bloodstream neutrophils with 50 u/ml recombinant granulocyte-macrophage colony-stimulating factor (rGM-CSF) primed the respiratory burst (as assessed by fMet-Leu-Phe stimulated luminol-dependent chemiluminescence) and resulted in a rapid (within 15 min) upregulation of expression of CD11b and CD18 (as measured by FACS analysis). This rapid priming and modulation of receptor expression was not inhibited by cycloheximide and hence appeared to be independent ofde novo protein biosynthesis. When neutrophils were incubated for up to 5 h in culture, the fluorescence distributions of CD11b and CD18 declined indicating the loss of expression of these receptors as the neutrophils aged, but in rGM-CSF treated suspensions receptor expression was maintained. When neutrophils were incubated in the presence of cycloheximide, they progressively lost their ability to generate reactive oxidants in response to fMet-Leu-Phe so that by 5 h incubation with this inhibitor they could only generate about 25% of the oxidative response stimulated in untreated cells, and the expression of CD16 and CD18 was grossly impaired. Similar effects were observed in rGM-CSF treated suspensions except that cycloheximide required longer incubation times (typically 4–5 h) before impairment of function or receptor expression occurred. These data show thatde novo protein biosynthesis is required for both the maintenance of neutrophil function and also for the continued expression of some plasma membrane receptors.Abbreviations fMet-Leu-Phe N-formylmethionyl-Leucyl-Phenylalanine - rGM-CSF recombinant granulocyte-macrophage colony-stimulating factor - FITC fluorescein isothiocyanate conjugate - Luminol 5-amino-2,3-dihydrophthalazine-1,4-dione