神经节苷脂制备中溶剂效率的研究

神经节苷脂在组织中的含量很低，分离、提取过程极其复杂，有机溶剂消耗量非常大。利用回收的有机溶剂，结合离心液相色谱技术，使有机溶剂用量下降了８８．５％，组织提取率达到０．０８９４％。     

Organophosphate Metasystox-induced Increment of Lipase Activity and Lipid Peroxidation in Cerebral Hemisphere: Diminution of Lipids in Discrete Areas of the Rat Brain

Abstract: The effects of the pesticide, metasystox (O,O-dimethyl-S-2 or Metasystor^® (ethylsulphinyl) ethylthiophosphate), on various lipid fractions in the discrete areas of the brain were studied. The daily intraperitoneal administration of 4 mg/kg body weight of metasystox for 10 days has depleted the levels of total lipids, phospholipids, cholesterol, esterified fatty acids and gangliosides in cerebral hemisphere, cerebellum, brain stem and spinal cord. But the lipase and lipid peroxidation measured in the cerebral hemisphere were significantly increased. It is possible that the inhibition of the lipid levels in the discrete areas of the brain may be due to the increase activity of lipase and lipid peroxidation.     

Effect of gangliosides on Na,K-ATPase activity and conformation of microsomal membranes

The effect of gangliosides on activity of Na,K-ATPase and K-dependent nitrophenyl-phosphatase was studied. Gangliosides in low concentrations were shown to activate Na,K-ATPase, but to inhibit it in high concentrations. In all concentrations used the gangliosides had only an inhibitory action on K-dependent nitrophenyl-phosphatase. Inhibition of the enzyme by gangliosides was reversible and competitive relative to K⁺. Calculation of Hill's coefficient showed that gangliosides, whether their action was activating or inhibitory, behaved as allosteric effectors. To elucidate the mechanism of action of gangliosides on the enzyme their effect on microsomal membranes was studied by the fluorescent probe method. Gangliosides were found to produce marked conformational changes in microsomal membranes of the brain.Department of Pharmacology and Department of General and Clinical Chemistry, Erevan Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Zakusov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 12, pp. 682–684, December, 1978.     

Prevention of experimental allergic encephalomyelitis by ganglioside GM4

Guinea pigs inoculated with a mixture of myelin basic protein and the myelin-specific ganglioside, sialosylgalactosylceramide (G_M4), do not develop the signs or neuropathology of experimental allergic encephalomyelitis. The results indicate that G_M4 cloaks the basic protein molecule so that it is no longer immunopathogenic in these animals. The interaction of basic protein with G_M4, previously shown in vitro, appears to be relevant to the pathogenesis of experimental allergic encephalomyelitis in guinea pigs.     

Molecular Microscopy of Brain Gangliosides: Illustrating their Distribution in Hippocampal Cell Layers

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Expression of GD3 disialoganglioside antigen on peripheral T-lymphocytes in patients with disseminated malignant melanoma

Abstract Disialoganglioside antigens GD2 and GD3 are expressed on most melanoma cells. On melanoma surrounding T-cells in immunohostological sections, disialogangliosides can also be found, as well as in a small % of T-lymphocytes in peripheral blood from healthy persons. In order to find out if there is a difference in ganglioside expression on peripheral T-lymphocytes between melanoma patients and healthy persons, we examined the expression of CD3 as T-lymphocytic antigen and GD2 or GD3 antigens, respectively, by flow cytometry. We used peripheral mononuclear blood cells of 12 patients with advanced disseminated malignant melanoma and of 12 healthy control donors. For immunostaining, murine monoclonal antibodies Leu-4, 14G2a and MB3.6 were used, recognizing CD3, GD2 and GD3. GD2 expression was found on only a low proportion of T-lymphocytes in patients and healthy persons (pat.: mean = 1.2%± 0.7%, co.: mean = 0.4%± 0.4%). Disialoganglioside antigen GD3, however, could be demonstrated on an average of 8.4%± 4.6% of patients' and on 4.0%± 2.1% of healthy persons' T-cells. There is a statistically significant difference (P < 0.01) between the data of patients' and control group. We conclude that there is a correlation between advanced malignant melanoma and expression of GD3 antigen on patients' peripheral T-lymphocytes. The immunological relevance of our findings is discussed.     

Characterization of sialidase activity in mouse synaptic plasma membranes and its age-related changes

Sialidase activity in synaptic plasma membranes (SPM) isolated from C57BL/6 mouse brain was examined using exogenous ganglioside substrates. The enzyme activity directed toward GM3 showed sharp pH dependency with optimal pH of 4.0, and was greatly enhanced by Triton CF-54, Nonidet P-40 or CHAPS. The apparent K_m and V_max values for enzyme activity in SPM were 11 μM and 164 pmol/mg protein/min, respectively. Examination of sialidase activities in subcellular fractions of brain tissues showed the enrichment of enzyme activity in SPM prepared from either young adult or senescent mice. Substrate specificity of SPM sialidase was compared with that of myelin sialidase using delipidated, solubilized enzyme preparations. The SPM sialidase hydrolyzed GD1a more effectively as compared with the myelin enzyme. While SPM sialidase could hydrolyze GM1, the hydrolytic rate by the SPM enzyme was significantly lower than that by the myelin enzyme. The sialidase activity in SPM decreased with increasing age; activity was highest between the ages of 4–7 months, decreased to a relatively constant level between 13–25 months, and reached its lowest level at 31 months. These results demonstrate that SPM contain a distinct sialidase activity which is regulated in an age-dependent manner. © 1995 Wiley-Liss, Inc.     

Glioma heterogeneity in vitro: the significance of growth factors and gangliosides

Despite renewed attempts by the WHO at updating the system of classification for brain tumours, most of the dynamic biological processes which underlie both the morphological appearances which form the basis for such systems and the malignant potential of gliomas remain an enigma to the neuropathologist. One feature recognized in human gliomas is their phenotypic and genotypic heterogeneity. Such cellular heterogeneity seen in the histological section is retained in vitro, at least during early passage. It is proposed that this heterogeneity is important in the growth and maintenance of the tumour and may be related to the activity of growth factors and gangliosides. Such molecules may not only influence the histoarchitecture of glial neoplasms but may also determine malignant progression and invasive potential. Moreover, there may be an intimate relationship between growth factors and gangliosides constituting an intricate feedback mechanism upon which the biological progression of gliomas depends.     

Ultrastructure of myocardium in the hurler syndrome

Summary Cardiac tissues obtained at post mortem examination of eight patients with the Hurler syndrome, who ranged in age from 5 to 23 years, were examined by histochemical methods and electron microscopy. Extensive myocardiocytic vacuolization and increased interstitial fibrous tissue were noted by light microscopy in all hearts. The cytoplasmic (perinuclear) vacuoles contained Luxol-fast-blue-positive substance. At the ultrastructural level, abnormal cytoplasmic organelles were present within the myocardiocytes in all patients. These organelles were of three types: zebra bodies (ZB), membranous cytoplasmic bodies (MCB) and granulomembranous bodies (GMB). As ZB and MCB are believed to represent the morphological counterpart of accumulated gangliosides, these substances rather than glycosaminoglycans appear to be stored within myocardiocytes of patients with the Hurler syndrome. The accumulation of gangliosides and the consequent damage to the myocardial substratum probably contributes to the clinically evident cardiac disease, so often observed in the patients with this disorder.Supported in part by grants-in-aid T.3-11 and 3-3 from the Ontario Heart Foundation, No. 766 from the Ontario Mental Health Foundation, Toronto, and a Special Research Fund, University Hospital, London, Ontario, CanadaPresented in part at the Annual Meeting of the Canadian Association of Pathologists, Quebec City, Quebec, Canada, June 16–20, 1979Recipient of a Medical Research Council of Canada Fellowship, 1978–1980