摘要:

AbstractTheiler's murine encephalomyelitis viruses causing both fatal encephalitis (GDVII virus) and chronic demyelinating disease (WW virus) are capable of replicating in isolated Schwann cell cultures. Light microscopy combined with immunohistochemical staining of viral antigens revealed that large numbers of Schwann cells infected with the two viruses show cytopathic effect (rounding) and contain viral antigens. Electron microscopy of virus‐infected Schwann cells shows that the morphological alterations that the cells undergo following infection by the two virus isolates are different. In the early stages of GDVII and WW virus infection, different inclusion bodies are formed in the cells cytoplasm. At late stages of the infection GDVII virions are found in all infected cells and are arranged in crystalline arrays around inclusion bodies. In contrast, in WW virus‐infected Schwann cells only in few cells virions were observed and they appeared aligned between two membrane un

ISSN:0360-4012    

DOI:10.1002/jnr.490150202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractSome acidic lipids including sulfatide and phosphatidylinositol were found to increase greatly the rate of cathepsin D cleavage of the myelin basic protein. Since a similar effect was seen when the substrate was changed to cytochrome C, but not when the enzyme was changed to pepsin, these acidic lipids seem to be acting on cathepsin D rather than on myelin basic protein itself. Even so, chemical modification studies suggest that this phenomenon is only seen when the myelin basic protein is in its native conformation. Succinylation of MBP increases its rate of cleavage by cathepsin D by at least tenfold and, in addition, with this modified and presumably denatured MBP as substrate, activation of cathepsin D is no longer seen with acidic lipids. These findings suggest that the native conformation of MBP is both an important determinant of its rate of cleavage by cathepsin D and is also essential for observing activation of this reaction by acidic lipids. The acidic lipids seem to alter the “extended active site” of cathepsin D in such a way as to enable this enzyme better to utilize the native myelin basic protein as a substrate. Cathepsin D has previously been implicated as the protease responsible for the release into cerebrospinal fluid in multiple sclerosis patients of an encephalitogenic fragment derived from myelin basic protein. It is possible that the elevated levels of cathepsin D and sulfatide that have previously been found associated with multiple sclerosis plaques in vivo act in concert to bring about the rapid cleavage and subsequent loss of the myelin basic protein from these localized regions in the myelin she

ISSN:0360-4012    

DOI:10.1002/jnr.490150203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractAntisera against the trout CNS myelin proteins 36K and IP2 were prepared in rabbits and characterized by immunoblot analysis and immunohistochemistry. The anti‐36K antiserum exclusively stained its corresponding antigen from trout CNS myelin but failed to recognize any myelin polypeptide from either trout PNS or mammalian CNS and PNS. Antibodies against the IP2 glycoprotein specifically cross‐reacted with related intermediate proteins (IP) of both CNS and PNS myelin from trout but only faintly labeled the P0protein of mouse peripheral nerve. Immunohistochemical localization of both antigens in the CNS of young trout was confined to the myelin sheath, except that anti‐36K antiserum also stained oligodendrocytes. Nodes of Ranvier, neuronal cell bodies, and dendrites, as well as other glial elements, were negative. Specificity of the immunofluorescent reaction was established by crossed immunoadsorption experiments. Whereas on adjacent sections through trout brain both antigens exhibited a nearly identical distribution pattern, immunostaining in peripheral nerves was seen only with anti‐IP2 ant

ISSN:0360-4012    

DOI:10.1002/jnr.490150204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractGangliosides inhibit the phosphorylation of both small and large rat myelin basic proteins (SMBP, LMBP) by an endogenous phospholipid‐sensitive Ca2+‐dependent protein kinase (C‐Kinase). Using a rat brain myelin preparation in an in vitro phosphorylation assay system, we determined the inhibition constants (IC50's) of the gangliosides GM1, GD1a, GD1b, and GT1bto be approximately 160 μM, 65 μM, 65 μM, and 40 μM, respectively. Asialoganglioside GA1, ceramide, and Nacetylneuraminic acid (NANA, sialic acid) failed to produce similar inhibition, suggesting that both the lipid and the sialic acid moieties are necessary, but neither alone is sufficient to produce inhibition. The results indicate that gangliosides may regulate protein kinase C activities in the nervo

ISSN:0360-4012    

DOI:10.1002/jnr.490150205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractPreviously we reported results of an incubation experiment with neurofilaments that supported the existence of a μ‐type of Ca2+‐activated neutral protease in the rat peripheral nerve; it was active with μM order Ca2+(μ‐CANP). This time, we partially purified the μ‐CANP from a crude CANP fraction of rat peripheral nerve by using a DE52 column and a Phenyl‐Sepharose column followed again by DE52 column chromatography. The presence of μ‐CANP was verified by an immunoblotting technique. The μ‐CANP degraded the neurofilament triplet as previously reported; i.e., among the neurofilament triplet, the 160K component was most sensitive, and in the order of the 160K, 68K, and 200K compo

ISSN:0360-4012    

DOI:10.1002/jnr.490150206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractNonidet P4O solubilized up to 90% of the sialidase, active towards added ganglioside substrate, that was associated with the total membrane fraction prepared from gray matter of bovine brains. Solubilized sialidase acted upon endogenous substrate (sialic acid containing compounds solubilized with the enzyme), hydrolyzing approximately 50% of the readily available sialosyl residues within 20 min. During a 2‐hr reaction time 80% of the polysialylated gangliosides solubilized with the enzyme were acted upon. A 20‐min lag was observed before sialidase acted upon added ganglioside substrate. The lag could be reduced to less than 2 min when the enzyme was allowed to act on endogenous substrate prior to exposure to exogenous substrate, suggesting that the solubilized enzyme acted preferentially on endogenous substrate. A protease inhibitor prevented much of the 86% loss of activity towards added substrate that was seen when the enzyme was stored at 4°C for 6 days; activity towards endogenous substrate decreased only

ISSN:0360-4012    

DOI:10.1002/jnr.490150207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractWe have previously communicated that heparan sulfate and heparin released 16S acetylcholinesterase (AChE) from cholinergic synapses. These experiments suggest that heparan‐like molecules are involved in the anchorage of AChE to the neuromuscular junction. In order to prove the in vivo interaction between the 16S AChE and heparan sulfate residues, the binding of exogenously added 16S enzyme to intact cells rich in cell‐surface heparan sulfate proteoglycans was examined; 16S AChE form was shown to bind to intact endothelial cells in a specific, time‐dependent, saturabel fashion. A single class of binding sites was involved and at saturation around 2.52 × 1011molecules of 16S AChE/cm2were bound. Fifty percent of the binding of the 16S AChE was blocked by heparan sulfate, heparin, or previous treatment of the cell with heparitinase. The binding was reversed by exogenous heparin, but not by chondroitin sulfate or hyaluronic acid. Our results demonstrate that the synaptic form of AChE binds to heparan sulfate proteoglycans on the surface of th

ISSN:0360-4012    

DOI:10.1002/jnr.490150208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractIn order to quantify the changes that occur in the cholinergic central nervous system with aging, we have compared acetylcholine (Ach) formation in brain cortex slice preparations from 2‐year‐old aged CBF‐1 mouse brains and compared the findings with those in 2–4‐month‐old young adult mouse brain slices. Incorporation of exogenous radioactively labelled choline (31 nM [3H] choline) into acetyl choline in incubated brain slices was linear with time for 90 min. Percentage of total choline label distributed into Ach remained constant from 5 min after starting the incubation to 90 min. In contrast, distribution of label into intracellular free choline (Ch) and phosphorylcholine (Pch) changed continuously over this period suggesting that the Ch pool for Ach synthesis in brain cortex is different from that for Pch synthesis. Incorporation of radioactivity into Ach was not influenced by administration of 10 μM eserine, showing that the increment of radioactivity in Ach reflects rate of Ach formation, independently from degradation by acetylcholine esterases. Under our experimental conditions, slices from cortices of aged 24‐month‐old mouse brain showed a significantly greater (27%) incorporation of radioactivity into intracellular Ach than those from young, 2–4‐month‐old, brain cortices. Inhibitors of Arch release, 1 mM ATP or GABA, had no effect. Since concentration of radioactive precursor in the incubation medium was very low (31 nM), the Ch pool for Ach synthesis in slices was labelled without measurably changing the size of the endogenous pool. These data suggest a compensatory acceleration of Ach synthesis or else a smaller precursor pool specific for Ach synthesis into which labelled Ch migrated in aged brain. We also measured in detail the incorporation of [3H]CH into choline phospholipids: phosphatidyl choline, lysophosphatidyl choline, and sphingomyelin of young and old mouse brain. We could not detect any difference between young and old mouse brain cortical slices, suggesting that the difference in Ach synthesis that we have observed may reflect a specific alteration with aging in the metabolic mecha

ISSN:0360-4012    

DOI:10.1002/jnr.490150209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractIn order to contribute evidence leading to establishing the excitatory pathways in the vertebrate retina, we selectively lesioned chick retinas by intraocular injection of 6, 60, 120, and 200 nmol of kainate, which selectively damages OFF‐bipolars, amacrines, horizontals, and ON‐bipolars, and measured the K+‐stimulated, Ca++‐dependent release of L‐(3H)‐glutamate and L‐(3H)‐aspartate. We also measured (3H)‐GABA release as a marker for horizontal cells and a population of amacrines, as well as (14C)‐glycine release as a tracer of a different subpopulation of amacrines. All four amino acids were released from control retinas by a depolarizing K+concentration in a Ca++‐dependent fashion. GABA and glycine, however, showed an additional Ca++‐independent component of release. Lesion induced by 6 nmol of kainate decreased by 50% the release of glutamate and by 20% that of aspartate; glycine release was reduced 40% while GABA release was unaffected. Injection of 60 nmol of kainate reduced glutamate release a further 20% and significantly decreased GABA (50%) and glycine (75%) release; aspartate release remained unmodified; 120 nmol of kainate caused a further 30% reduction in aspartate and GABA release. Neither compound was significantly released after treatment with 200 nmol of kainate. These results seem to suggest that while OFF‐bipolars could release glutamate as transmitter, aspartate is released from a different cell population which is less sensitive to kain

ISSN:0360-4012    

DOI:10.1002/jnr.490150210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractBioelectrical responses evoked in the ventrolateral funiculus (VLF) of the spinal cord by electrical stimulation of the contralateral hind limb were studied following topical application of 1% morphine solution to the somatosensory SI area of the rat cerebral cortex. After morphine, a typical pattern was observed in the electrocorticogram, characterized by the appearance of rhythmic spiking activity. Time‐related with each cortical spike, a significant reduction in the amplitude of VLF responses was observed. It is concluded that cortical excitation induced by morphine generates descending influences having the ability to inhibit spinal sensory transmissio

ISSN:0360-4012    

DOI:10.1002/jnr.490150211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY