聚氯乙烯增塑糊流变行为的研究——Ⅳ.表面活性剂的影响

本文研究了各类表面活性剂对聚氯乙烯增塑糊流变行为的影响。阴离子表面活性剂使其增塑糊有较高致流值,呈明显假塑性流动;阳离子和非离子表面活性剂使其增塑糊有低的表观粘度,接近牛顿型流动。测定了聚氯乙烯粒子表面的Zeta电位和接触角,并讨论了表面活性剂影响增塑糊流变性能的机理。     

An immunohistochemical study of MAP2 and clathrin in gerbil hippocampus after cerebral ischemia

Changes in MAP2 and clathrin immunoreactivity were studied in gerbil hippocampus after transient cerebral ischemia. MAP2 immuno-reactivity decreased significantly by 1 h in the subiculum-CA1 and CA2 areas which correspond to reactive change, while no decrease was observed in CA1 until day 4. Before the initiation of delayed neuronal death, MAP2 immunoreactivity was not changed in CA1. On the other hand clathrin immunoreactivity increased in the pyramidal cell layer of CA1 by 3 h after ischemia and remained high for 2 days. Clathrin immunoreactivity in the pyramidal cell layer of CA1 diminished after delayed neuronal death. The transient change of clathrin was noted especially in CA1 in the period prior to delayed neuronal death. These results imply an abnormal change in clathrin turnover after ischemia, which may participate in the pathogenesis of delayed neuronal death.     

HPLC/MS Determination of Enalapril and Enalaprilat in the Blood Plasma

A reproducible and sensitive analytical procedure has been developed for the quantitative determination of enalapril and enalaprilat in the blood plasma by high-performance liquid chromatography with mass-spectrometric detection (HPLC/MS). For increasing the sensitivity and reproducibility of analyses, the samples were treated with diazomethane in order to obtain methyl esters of the analyzed compounds. The quantitative determination was carried out using the internal standard method; the internal standard was captopril. The detection was performed in the positive ion mode for ions with m/z = 377 (enalaprilat methyl ester), 391 (enalapril methyl ester), and 267 (captopril methyl ester). Enalapril, enalaprilat, and captopril were isolated from the blood plasma and purified by means of solid-phase extraction. The calibration plot is linear in the concentration range from 0.5 to 200 ng/ml. The detection limits for both enalaprilat and enalapril in the blood plasma are 0.1 ng/ml.__________Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 39, No. 2, pp. 49 – 52, February, 2005.     

Altered genetic response to beta-adrenergic receptor activation in late passage C6 glioma cells.

Previous studies have demonstrated variability in the phenotype of rat C6 glioma cells. In the present study, we compared morphology, growth rate, and beta-adrenergic regulation of gene expression in early (P39-47) and late (P55-90) passage C6 cells. Morphological changes were observed in five independently derived, late passage populations. In four of the five, the untreated cells were more polygonal than the fibroblast-like parental cells, and only a small fraction exhibited process outgrowth after dbcAMP treatment. Untreated cells from the fifth late passage population had longer cytoplasmic processes than parental cells and responded to dbcAMP with further process outgrowth. All late passage populations had shorter generation times than the parental cells. In early passage cells, treatment with the beta-adrenergic agonist, isoproterenol (IPR), resulted in an increase in c-fos mRNA and a decrease in c-jun mRNA (Gu-bits RM, Yu H: J Neurosci Res, 30:625-630, 1991). Both of these immediate early gene responses were irreversibly lost between P50 and P55. Additional differences in basal or IPR-induced mRNA levels were observed for beta-APP, GFAP, NGF, and PPE, but not for a number of other mRNAs. These results are discussed in relationship to previously described differences in the ability of early and late passage C6 cells to accumulate cAMP (Mallorga P, et al.: Biochim Biophys Acta 678:221-229, 1981).