大鼠离体脑片癫痫放电特征及EC—海马环路的作用

目的和方法：采用４００～５００μｍ大鼠水平脑切片强直电刺激海马Ｓｃｈａｅｆｅｒ侧枝（６０Ｈｚ、２ｓ）全细胞、细胞外同步记录ＣＡ１神经元胞体电活动和相应树突区场电位,探讨其在癫痫发生中的作用。结果：①５３片脑片上记录到细胞内、外同步发生的原发性后放,持续２０ｓ以上,放电形式和持续时间常在第６个刺激串后趋于稳定。ＣＡ１神经元的原发性后放常跟在强直电刺激引起的阵发性去极化或超极化偏移之后（ＰＤＳ、ＰＨＳ）。它可以从紧张性放电向爆发性放电转化,振幅逐渐递增并与细胞外癫痫样放电同步,产生癫痫放电极性偏移;②其中８／４０脑片细胞外可记录到继发性后放之后出现的自发性发作样癫痫放电,长达数分钟,与全细胞记录的ＥＰＳＰ同步。切断ＥＣ与海马之间的联系可以易化海马癫痫电活动（３／５）。结论：ＥＣ输入到海马的神经通路可能在封闭的ＥＣ海马环路中起着重要的门控作用     

TREATMENT OF RAT PROXIMAL AND DISTAL COLONIC CELLS WITH SODIUM ORTHOVANADATE ENHANCES THEIR ADHESION AND SURVIVAL IN PRIMARY CULTURE

We have studied the effect of sodium orthovanadate, an inhibitor of protein tyrosine phosphatases, on primary cultures of colonocytes and stromal cells. Everted proximal and distal colonic tissue of adult rats were disintegrated by a collagenase/dispase solution for 60 min at 37°C to prepare viable gland fragments and isolated cells. Cell preparations were inoculated onto plastic substratum or cytodex-3 microcarriers in a defined maintenance medium or in 1% fetal calf serum media. Incorporation of sodium orthovanadate (≥50 μm) in these media constantly enhanced the survival (cell enumeration and trypan blue exclusionP<0.05) and the adhesion (up to four-fold by crystal violet staining,P<0.01) of colonocytes (characterized by cytokeratin-18, transforming growth factor-α or alkaline phosphatase expression) and stromal cells. Removal of sodium orthovanadate from culture media restored cellular death processes. Incorporation of 10 mmn-butyric acid did not promote cell adhesion and survival except for distal cells exposed to 2 mm sodium orthovanadate. Besides studies in the regulation of anoikis in primary culture, the model will help to assay the influences of dietary and growth factors on the biology of non-cancerous colonic cells.     

A 0.5 G, 60 Hz magnetic field suppresses melatonin production in pinealocytes

The objective of this study was to develop a model for testing various hypotheses concerning possible mechanisms whereby electromagnetic fields might induce suppression of nighttime melatonin production in rodents. A published method for digesting freshly obtained pineal glands to the single cell level was modified, yielding better than 95% viability. An in vitro exposure facility developed for the Food and Drug Administration was used for 12-h overnight exposures of primary pinealocyte cultures to 0.05 mT, 60 Hz, vertical AC and 0.06 μT, DC fields. After exposure, cells were separated from the supernatant by centrifugation. Supernatant melatonin was measured by ELISA assays. Data from 10 experiments demonstrated an average 46% reduction in norepinephrine-induced production of melatonin in the pinealocytes. The results support the hypothesis that EM exposure can produce pineal gland melatonin suppression by affecting individual cells. Bioelectromagnetics 19:123–127, 1998. Published 1998 Wiley-Liss, Inc.     

Activation and glucagon regulation of mitogen-activated protein kinases (MAPK) by insulin and epidermal growth factor in cultured rat and human hepatocytes

Many hepatocellular activities may be proximally regulated by intracellular signalling proteins including mitogen-activated protein kinases (MAPK). In this study, signalling events from epidermal growth factor (EGF) and insulin were examined in primary cultured human and rat hepatocytes. Using Western immunoblots, rat and human hepatocytes were found to produce a rapid tyrosine phosphorylation of the EGF receptor and MAPK following 0·5–1 min exposure to EGF. Phosphorylation of p42 and p44 MAPK was observed following 2·5 min exposure to EGF. Insulin treatment produced phosphorylation of the insulin receptor β subunit; shc phosphorylation was not observed. MAPK phosphorylation corresponded with a shift in molecular weight and an increase in kinase activity. Insulin-dependent activation of MAPK was unequivocally observed only in human hepatocytes, though a slight activation was detected in rat. Co-treatment with insulin and EGF produced phosphorylation and complete electrophoretic shift in molecular weight of MAPK, with an additive or synergistic increase in enzyme activity in rat but not human hepatocytes; human hepatocyte MAPK was maximally stimulated by EGF alone. Glucagon pretreatment blocked phosphorylation, gel mobility shift and kinase activity of MAPK induced by insulin but only partially blocked EGF-induced MAPK activation in human hepatocytes. Glucagon also reduced the activation of MAPK by EGF in rat hepatocytes. Pre-treatments with forskolin or cyclic AMP analogues diminished in the insulin-, EGF- and insulin plus EGF-dependent activation of MAPK in rat hepatocytes without effecting phosphorylation of receptors or MAPK. These results indicate that although EGF and insulin may both signal through the MAPK/ras/raf/MAPK pathway, the response for MAPK differs between these ligands and between species. Further, in both rat and human, glucagon exerts its effects through a cyclic AMP-dependent mechanism at a level in the insulin and EGF signal transduction pathways downstream of MAPK but promixal to MAPK. The partial inhibition of EGF-induced MAPK phosphorylation by glucagon in human hepatocytes provides further evidence for a raf-1-independent pathway for activation of MAPK. © 1998 John Wiley & Sons, Ltd.     

Effects of maternal uninephrectomy on the development of fetal rat kidney: Numerical and volumetric changes of the glomerulus and formation of the anionic site in the glomerular basement membrane

Developmental processes of the fetal rat kidney from uninephrectomized mothers were studied. The uninephrectomy was performed on day 5 of gestation. Glomerular number and volume in the fetal kidneys on days 18, 20, and 22 of gestation were morphometrically determined. To investigate the anionic site formation in the glomerular basement membrane, distribution of cationized ferritin (CF) in the fetal glomerulus was examined electron microscopically after CF injection. Blood urea nitrogen (BUN) concentration in the pregnant rats was also determined on various days after uninephrectomy. On fetal days 20 and 22, the glomerular volume was significantly larger in the fetuses from uninephrectomized mothers than in those from sham-operated ones. On fetal day 20, the CF particles were clustered in the laminae rarae interna and externa of the glomerular basement membrane in the fetuses from uninephrectomized mothers, while the clusters were arrayed in three to four layers in the glomerular basement membrane in the fetuses from sham-operated ones. On fetal day 22, the CF particles noted in the lamina rara externa in the fetuses from uninephrectomized mothers were slightly larger in number than such particles in the age-matched control fetuses. The BUN concentration of the uninephrectomized pregnant rats was significantly higher than that of the sham-operated pregnant ones on each postoperative day. These results suggest that the development of the fetal renal glomerulus is accelerated by the elevated BUN level following maternal uninephrectomy when the fetal kidney is functional in effective filtration in the rat. J. Morphol. 238:337–342, 1998. © 1998 Wiley-Liss, Inc.     

Species-dependent enantioselective pharmacokinetics of PNU-103017, a Pyrone HIV protease inhibitor

PNU-103017, 4-Cyano-N-(3-(cyclopropyl(5,6,7,8,9,10-hexahydro-4-hydroxy-2-oxo-2H-cycloocta(b) pyran-3-yl)methyl)phenyl)-benzenesulfonamide, is a selective HIV aspartyl protease inhibitor under evaluation as a potential oral treatment of Acquired Immunodeficiency Diseases. PNU-103017 is a racemic mixture of two enantiomers, designated PNU-103264 (R-) and PNU-103265 (S-). Stereoselective pharmacokinetics of the two enantiomers of PNU-103017 were observed in the dog, rat, and human after single and multiple dose administration of the racemate and were apparently species-dependent. Mean enantiomeric ratios of plasma concentrations (R-/S-) at each time point were greater than 1 in the dog, ranging from 1.22 to 3.06, but less than 1 in the rat and in the human, ranging from 0.44 to 0.80 and 0.23 to 0.73, respectively. A trend towards increased or decreased (farther from 1:1, R-/S-) enantiomeric ratio of plasma concentrations with time after each administration was also observed. The enantiomeric ratio remained unchanged after multiple dose administration in the rat, dog, and human although enzyme induction and increased plasma clearance were observed for both enantiomers. Chirality 10:210–216, 1998. © 1998 Wiley-Liss, Inc.     

Measurement of whole blood phagocyte chemiluminescence in the Wistar rat

The factors influencing the rat whole blood chemiluminescence (CL): concentrations of blood, luminol, zymosan or opsonized zymosan, volume of the reaction mixture, storage time of blood samples and the presence of anticoagulants were evaluated. The CL micromethod described provides a fast and sensitive tool for the determination of metabolic activity of phagocytes in the microlitre range of rat whole blood. © 1997 John Wiley & Sons, Ltd.