毛细管电泳技术分离哺乳动物脑组织中神经节苷脂

利用毛细管电泳（ｃａｐｉｌｌａｒｙｅｌｅｃｔｒｏｐｈｏｒｅｓｉｓ，ＣＥ）分离猪脑、鼠脑组织中主要几种神经节苷脂ＧＭ_１、ＧＤ_（１ａ）、ＧＤ_（１ｂ）、ＧＴ_（１ｂ），在缓冲液中加入α－环状糊精（α－ｃｙｃｌｏｄｅｘｔｒｉｎ，α－ＣＤ）来提高分离的选择性和效率，并对缓冲液的ｐＨ值、α－ＣＤ浓度和电压等变化因素进行研究。结果表明在含１５．０ｍｍｏｌ／Ｌα－环状糊精的２．５ｍｍｏｌ／Ｌ磷酸级冲液（ｐＨ８．６）中，电压为２５ｋＶ时能很好的分离生物样品。从猪脑提取物中分离出ＧＭ_３、ＧＭ_１、ＧＤ_（１ａ）、ＧＤ_（１ｂ）、ＧＴ_（１ｂ）和含唾液酸的其他糖脂类物质，鼠脑中分离出ＧＭ_１、ＧＤ_（１ａ）和ＧＴ_（１ｂ），说明毛细管电泳可用于分离神经节苷脂，具有快速、简便、节约等特点。     

Determinants of differential liver-colonizing potential of variants of the MCA-38 murine colon cancer cell line

We investigated factors that might contribute to the differing liver tumor colonizing potentials of MCA-38 colonic cancer cell line variants injected into the ileocolic veins of C57B1/6J mice. Non-colonizing (MCA-38 CD) cells were sensitive to lysis by hepatic ntural killer (NK) cells in vitro (⁵¹ Cr-release assay) and cells with high liver-colonizing potential (MCA-38 LD) were resistant. Following abrogation of NK activity by treatment with anti-asialoG_M1, liver-colonizing ability of LD cells but not CD cells was enhanced. MCA-38 CD cells were, however, capable of initial liver colonization after ileocolic vein injection. Differing patterns of membrane sialylation may have contributed to the contrasting hepatic tumorigenicities of LD and CD cells; -galactoside 2,6-sialyltransferase mRNA levels and activity were four-fold higher in LD than CD cells and qualitative and quantitative differences existed between their ganglioside profiles. In the MCA-38 model outlined, tumor cell susceptibility or resistance to NK lysis was a relatively unimportant determinant of liver-colonizing potential.     

2,4-Dichlorophenoxyacetic acid disrupts the cytoskeleton and disorganizes the Golgi apparatus of cultured neurons.

2,4-Dichlorophenoxyacetic acid (2,4-D) is a potent neurotoxic herbicide widely used in agriculture. The basic mechanisms by which 2,4-D produces cell damage have not yet been determined. In this study we have examined the effects of 2,4-D in primary cultures of cerebellar granule cells in order to obtain insights into the possible mechanisms underlying the toxic effects of this herbicide. The results obtained indicate that a 24-hour exposure to 2,4-D produces a striking and dose-dependent inhibition of neurite extension. This phenomenon is paralleled by a significant reduction in the cellular content of both dynamic and stable microtubules, a disorganization of the Golgi apparatus, and an inhibition in the synthesis of complex gangliosides. Interestingly, 2,4-D inhibits the in vitro polymerization of purified tubulin. Taken together, the present observations raise the possibility that at least one basic mechanism underlying 2,4-D neurotoxicity involves an inhibition of microtubule assembly. That event may cause a decreased neurite outgrowth response, and could also explain the observed differences in the pattern of ganglioside biosynthesis and/or the disorganization of the Golgi apparatus.     

Factors defining target specificity in antibody-mediated neuropathy: Density-dependent binding of anti-GD1a polyclonal IgG from a neurological patient

IgM and IgG antibodies reacting with components of human brain gangliosides were detected in a patient bearing severe sensory ataxy. Using different chemical and immunological methods, the antigen was identified as the GD_1a ganglioside. The antibodies showed antigen “density-dependent” binding, a property only observed in tumor-specific monoclonal antibodies. The relevance of this result in regard with target specificity of neuropathy-associated antibodies directed to ubiquitous glycolipids is discussed. J. Neurosci. Res. 47: 636–641, 1997. © 1997 Wiley-Liss, Inc.     

Sialidase NEU3 contributes neoplastic potential on colon cancer cells as a key modulator of gangliosides by regulating Wnt signaling

The plasma membrane‐associated sialidase NEU3 is a key enzyme for ganglioside degradation. We previously demonstrated remarkable up‐regulation of NEU3 in various human cancers, with augmented malignant properties. Here, we provide evidence of a close link between NEU3 expression and Wnt/β‐catenin signaling in colon cancer cells by analyzing tumorigenic potential and cancer stem‐like characteristics. NEU3 silencing in HT‐29 and HCT116 colon cancer cells resulted in significant decrease in clonogenicity on soft agar and in vivo tumor growth, along with down‐regulation of stemness and Wnt‐related genes. Analyses further revealed that NEU3 enhanced phosphorylation of the Wnt receptor LRP6 and consequently β‐catenin activation by accelerating complex formation with LRP6 and recruitment of GSK3β and Axin, whereas its silencing exerted the opposite effects. NEU3 activity‐null mutants failed to demonstrate the activation, indicating the requirement of ganglioside modulation by the sialidase for the effects. Under sphere‐forming conditions, when stemness genes are up‐regulated, endogenous NEU3 expression was found to be significantly increased, whereas NEU3 silencing suppressed sphere‐formation and in vivo tumor incidence in NOD‐SCID mice. Increased ability of clonogenicity on soft agar and sphere formation by Wnt stimulation was abrogated by NEU3 silencing. Furthermore, NEU3 was found to regulate phosphorylation of ERK and Akt via EGF receptor and Ras cascades, thought to be additionally required for tumor progression. The results indicate an essential contribution of NEU3 to tumorigenic potential through maintenance of stem‐like characteristics of colon cancer cells by regulating Wnt signaling at the receptor level, in addition to tumor progression via Ras/MAPK signaling.     

神经节苷脂对大鼠坐骨神经损伤后Wallerian变性的预防作用

神经节苷脂对大鼠坐骨神经损伤后Ｗａｌｅｒｉａｎ变性的预防作用１马鸣超王捷（沈阳军区军事医学研究所，沈阳１１００３１）神经节苷脂（ｇａｎｇｌｉｏｓｉｄｅｓ，Ｇａｎ）是一类存在于大多数细胞膜上的糖鞘脂，特别存在于神经细胞膜上．有关其作用已有大量文献报道，...     

Protective effects of exogenous gangliosides on ROS-induced changes in human spermatozoa

This article summarizes the available evidence on the efficacy of gangliosides to reduce the degree of reactive oxygen species (ROS)-mediated damage. The antioxidative efficacy of exogenous gangliosides in protecting different cells encouraged us to examine their ability to protect human spermatozoa. Gangliosides are sialic acid-containing glycosphingolipids with strong amphiphilic character due to the bulky headgroup made of several sugar rings with sialic acid residues and the double-tailed hydrophobic lipid moiety. The amphiphilicity of gangliosides allows them to exist as micelles in aqueous media when they are present at a concentration above their critical micellar concentration. The protective effect of ganglioside micelles on spermatozoa is believed to stem from their ability to scavenge free radicals and prevent their damaging effects. In our study, we particularly focused our attention on the protective effect of ganglioside micelles on DNA in human spermatozoa exposed to cryopreservation. The results indicate that ganglioside micelles can modulate the hydrophobic properties of the sperm membrane to increase tolerance to DNA fragmentation, thus protecting the DNA from cryopreservation-induced damage. Further actions of ganglioside micelles, which were documented by biochemical and biophysical studies, included (i) the modulation of superoxide anion generation by increasing the diffusion barrier for membrane events responsible for signal translocation to the interior of the cell; (ii) the inhibition of iron-catalysed hydroxyl radical formation due to the iron chelation potential of gangliosides; and (iii) inhibition of hydrogen peroxide diffusion across the sperm membrane.     

神经节苷脂治疗儿童病毒性脑炎的疗效观察

目的观察神经节苷脂治疗儿童病毒性脑炎（VE）的疗效。方法98例VE患儿,随机分成对照组49例和治疗组49例,两组性别、病情轻重差异无统计学意义（P〉0．05）。两组均进行常规综合治疗,对照组予在常规治疗基础上给予胞二磷胆碱治疗,治疗组在常规治疗上给予神经节苷脂治疗,对两组治疗效果进行比较。结果治疗组在临床症状及体征恢复时间较对照组缩短,显效率和总有效率明显高于对照组,两组疗效有显著差异（P〈0．01）,治疗组明显优于对照组。结论神经节苷脂辅助治疗VE能提高疗效,减少并发症,具有重要的临床推广应用价值。