甜菜碱通过钙通道升高鼠脾淋巴细胞内[Ca^2＋]i研究

研究甜菜碱对小鼠脾淋巴细胞内钙离子浓度的变化及相关钙通道的研究．应用激光共聚焦显微镜（LSCM）测小鼠脾淋巴细胞内钙浓度的变化，应用不同钙通道阻滞剂研究甜菜碱影响细胞内钙浓度变化途径．对终浓度4mmol／L甜菜碱作用淋巴细胞不同时间的细胞内钙离子浓度值分析表明：甜菜碱可以使淋巴细胞内Ca^2＋浓度升高，6h后效果最明显；对加入不同阻滞剂细胞内钙离子浓度变化分析表明：钙通道及蛋白阻滞剂硝苯地平、地尔硫卓、咪贝地尔、金雀异黄素对甜菜碱升高淋巴细胞内钙离子浓度没有影响；维拉帕米、新霉素、肝素、普鲁卡因能阻断甜菜碱对淋巴细胞内钙离子浓度的升高作用．由此可知：细胞内钙离子浓度升高主要通过以下途径：在G蛋白介导下通过影响L-型电压门控钙通道的仅。亚单位而引起外钙内流；通过影响胞内钙库的ILR钙通道和RyR钙通道而引起内钙外排．其共同引起胞质钙离子浓度增加．     

水中微囊藻毒素高效液相色谱检测与前处理条件优化

通过对前处理过程中关键环节进行单因素不同水平比较,以及运用正交试验设计进行多因素综合分析,优选出洗脱剂、淋洗剂、固相萃取柱、浓缩定容方式等因素的最优试验方案,建立实用简便易行的一般水样前处理流程.微囊藻毒素高效液相色谱进样分析时,选用甲醇-0.05%三氟乙酸水溶液作为流动相进行梯度洗脱,对于MC-RR和MC-LR取得较好分离效果,水样检出限可达0.02 μg/L.优化后的前处理、检测方法,对MC-RR,MC-LR平均回收率分别为88.9%和92.1%.另外,对于总(胞内胞外)微囊藻毒素的检测前处理,冰乙酸处理法优于其他处理法.优化后的方法已成功应用于不同水域环境样本的藻毒素分析.     

Regulation of the arachidonic acid-stimulated respiratory burst in neutrophils by intracellular and extracellular calcium

The respiratory burst is an important physiological function of the neutrophils in killing the bacteria invading in human body. We used chemiluminescence method to measure the exogenous arachidonic acid-stimulated respiratory burst, and measured the cytosolic free calcium concentration in neutrophils by the fluorescence method. It was found that, on one hand, the arachidonic acid-stimulated respiratory burst was enhanced by elevating the cytosolic free calcium concentration in neutrophils with a potent endomembrane Ca2+-ATPase inhibitor, Thapsgargin; on the other hand, chelating the intracellular or extracellular calcium by EGTA or BAPTA inhibited the respiratory burst. Results showed that calcium plays an important regulatory role in the signaling pathway involved in the exogenous arachidonic acid-stimulated respiratory burst of neutrophils.     

用近红外光谱法实时监测蛹虫草发酵中胞内多糖的质量浓度

应用近红外光谱(NIR)结合偏最小二乘法(PLS)建立一种实时监测蛹虫草发酵中胞内多糖质量浓度的新方法.对39个批次的蛹虫草在3个不同条件的5L发酵罐中进行蛹虫草深层发酵,发酵过程中间隔一定时间取样,采集样品的近红外光谱,并按常规方法测定样品中胞内多糖质量浓度,再采用PLS法建立样品的近红外光谱与胞内多糖质量浓度间的模型,所建模型经过选择最适光谱预处理方法和最适隐变量数进行优化,其留一交互验证预测值与化学测定参考值间的相关系数R=0.8750,交互验证均方根误差RMSECV=0.3052.采用最优PLS模型对样品中胞内多糖质量浓度进行预测,校正集预测均方根误差RMSEC=0.1670,预测集预测均方根误差RMSEP=0.3650,表明模型的稳健性和预测性能较好。     

δ-Protocadherins: unique structures and functions

δ-Protocadherins constitute a group of cadherins characterized by several conserved motifs in their cytoplasmic domains. We present a phylogenetic analysis that further divides this group into δ1-protocadherins (comprising protocadherin-1, −7, −9 and −11 or -X/Y) and δ2-protocadherins (comprising protocadherin-8, −10, −17, −18 and −19). The δ-protocadherin genes, which are located on different chromosomes in man and mouse, have a similar gene structure. They are expressed as multiple splice forms, differing mostly in their cytoplasmic domains. Some δ-protocadherins were reported to mediate weak cell-cell adhesion in vitro and cell sorting in vivo. In addition, individual δ-protocadherins might play important roles in signaling pathways, as they bind to proteins such as TAF1/Set, protein phosphatase-1α and the Frizzled 7 receptor. The spatiotemporally restricted expression of δ-protocadherins in different tissues and species and the results of their functional analysis, mainly in Xenopus, suggest that they play multiple, tightly regulated roles in vertebrate development. Received 18 July 2005; received after revision 26 August 2005; accepted 2 September 2005     

HLA-G protein processing and transport to the cell surface

Data are presented on the intracellular trafficking of HLA-G protein, taking the unique features of this non-classical molecule into consideration: the existence of seven isoforms resulting from alternative splicing (HLA-G1 to G7), and reduced tail length compared with HLA class I antigens. Biochemical studies and analysis of viral strategies for escaping the host immune system led to the demonstration that (i) both the membrane-bound (HLA-G1) and the soluble (HLA-G5) forms of the molecule require peptide association for cell surface expression, using TAP-dependent or TAP-independent pathways; (ii) peptide loading onto the HLA-G protein plays a critical role in controlling the quality of the molecule reaching the cell surface; (iii) surface expression of truncated HLA-G molecules is possible, and (iv) HLA-G expression may be restricted to soluble HLA-G5. These data reveal that HLA-G presents specific cell trafficking pathways and strongly support the contention that the primary function of HLA-G is as of an inhibitor ligand for immune-competent cells. Received 4 June 2002; accepted 2 July 2002 RID="*" ID="*"Corresponding author.     

Cellular microbiology of intracellular <Emphasis Type="Italic">Salmonella enterica</Emphasis>: functions of the type III secretion system encoded by <Emphasis Type="Italic">Salmonella</Emphasis> pathogenicity island 2

The facultative intracellular pathogen Salmonella enterica resides in a special membrane compartment of the host cell and modifies its host to achieve intracellular survival and proliferation. The type III secretion system encoded by Salmonella pathogenicity island 2 (SPI2) has a central role in the interference of intracellular Salmonella with host cell functions. SPI2 function affects antimicrobial defense mechanisms of the host, intracellular transport processes, integrity and function of the cytoskeleton and host cell death. These modifications are mediated by translocation of a large number of effector proteins by the SPI2 system. In this review, we summarize recent work on the cellular phenotypes related to SPI2 function and contribution of SPI2 effector proteins to these manipulations. These studies reveal a complex set of pathogenic interferences between intracellular Salmonella and its host cells.Received 11 June 2004; received after revision 8 July 2004; accepted 12 July 2004     

Effect of Aβ1-40 on membrane permeability and intracellular free Ca2+ of nerve cells

The effects of soluble and fibrillar Aβ1-40 on membrane permeability and intracellular free Ca^2 of nerve cells were investigated by the laser confocal microscopy. Results indicate that: i) Effects of soluble and fibrillar Aβ1-40 on cell membrane permeability are both concentration-dependent. Soluble Aβ1-40 increases membrane permeability only at concentration of 3μmol/L, while the toxic effect of fibrillar Aβ1-40 is much stronger, its evident effect begins from 1μmol/L. When its concentration rose to 3μmol/L, not only the membrane permeability increased, but also the nuclear membrane broke seriously, ii) Both soluble and fibrillar Aβ1-40 at high concentrations increased the intracellular free Ca^2 , and the increased amplitudes are concentration-dependent. However, the fibrillar one induces the increase of intracellular Ca^2 much quicker and synchronously.These results indicate that some correlation exists between the neurotoxicity of high concentration soluble and fibrillar Aβ1-40 and the change of physico-chemical properties and intracellular Ca ion imbalance.     

不同浓度ET-1引起心肌细胞[Ca2+]i 升高作用的量效关系

目的：探讨内皮素－１（ＥＴ－１）对心肌细胞内游离钙浓度（［Ｃａ２＋］ｉ）的作用以及不同浓度ＥＴ－１引起［Ｃａ２＋］ｉ升高作用的量效关系。方法：采用分离的Ｓｐｒａｇｕｅ－Ｄａｗｌｅｙ大鼠心室肌细胞,以Ｆｕｒａ－２／ＡＭ荧光指示剂负载,检测不同浓度ＥＴ－１引起［Ｃａ２＋］ｉ变化。结果：ＥＴ－１引起［Ｃａ２＋］ｉ升高呈双相反应,即起始的短暂快速相和随后的持续相。在１×１０－９～５×１０７ｍｏｌ／Ｌ范围内,随着ＥＴ－１浓度的增加,其升高［Ｃａ２＋］ｉ的作用亦增强;并且这种作用可被ＥＴＡ的特异性受体阻断剂ＢＱ１２３（２×１０６ｍｏｌ／Ｌ）所阻断。结论：ＥＴ－１升高［Ｃａ２＋］ｉ呈剂量依赖关系,其作用具有特异性,并且是通过ＥＴＡ受体介导的。