摘要:

Abstract—Slices of rabbit spinal cord were incubated with [3H]tyrosine and [35SO4] in the presence of either 5% antiserum to myelin basic protein or 0.21 mM‐puromycin. The degree of incorporation of the precursors into the basic protein (BP), the proteolipid protein (PLP) and into sulphatides, as a representative lipid, in isolated myelin was investigated. Anti‐BP serum inhibited the incorporation of [3H]tyrosine into BP and PLP from 22 to 46% as compared to controls, whereas puromycin nearly completely inhibited incorporation. The incorporation of [35SO4] into sulphatides was inhibited by anti‐BP serum from 20 to 34% and by puromycin from 33 to 65% as compared to controls. These alterations were myelin‐specific as shown by the equal or even increased incorporation of the precursors into the homogenates of spinal cord. The results are discussed in relation to the interaction of lipids and proteins in membrane

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb12252.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—The metabolism of rat brain sphingomyelins containing short‐chain (C16‐C18) and long‐chain (C20‐ C24) fatty acids has been studied by determination of the content of radioactivity in the sphingo‐sinc. fatty acids and phosphate of the sphingomyelins over a period of 60 days following the intracisternal injection of [14C]acetate and [32P]phosphate. From the rate of decrease of the specific radioactivities of the different constituents of short‐chain fatty acid sphingomyelins, we have calculated a half‐life of 65 days for sphingosine. 41 days for fatty acids and 62 days for phosphate. For the long‐chain fatty acid sphingomyelins the half‐life of sphingosine was approximately 465 days. The fatty acids and phosphate from these sphingomyelins had fast and slow turnover pools. The half‐life for the fast pool was 7 days for the two constituents and the estimated half‐lives for the slow pool were 220 days for fatty acids and 480 days for phosphate.These results suggest that one can distinguish at least three metabolic pools of brain sphingomyelins: (a) sphingomyelins with long‐chain fatty acids situated in myelin whose half‐lives are 465 days for sphingosine, 220 days for fatty acids and 480 days for phosphate; (b) sphingomyelins with long‐chain fatty acids located mainly in non‐myelin structures having half‐lives of 465 days for sphingosine. 7 days for fatty acids and 7 days for phosphate; (c) sphingomyeiins with short‐chain fatty acids with half‐lives of 65 days for sphingosine. 41 days for fatty acids and 62 days for phosphate. The differences between the half‐lives of the three metabolic pools of sphingomyelin, together with the subcellular localizations of the two molecular species of these compounds, suggest that the metabolism of the different molecular species of sphingomyelin are independent and that in various subcellular fractions the long‐chain fatty acid and short‐chain fatty acid s

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb12253.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—In slice preparations the exchange of dissolved substances between cells and incubation medium is delayed by diffusion through the extracellular space. The delay may seriously interfere with the study of membrane transport in terms of unidirectional fluxes across the cell membranes. A three‐compartment serial model has been developed to describe exchange between slice and incubation medium. By aid of this model it is shown that the diffusion delay prevents determination of unidirectional fluxes for the two non‐metabolizable glucose analogues 3‐O‐methylglucose and α‐methyl‐glucosidc. The membrane transport of the slowly transported α‐methylglucoside can however be examined by aid of the model whereas the transport of 3‐O‐methylglucose is so rapid that it can not be examined with respect to VmaxKmand Kr. An attempt to determine these parameters will result in falsely large values which reflect extracellular diffusion and n

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb12254.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—The glucose analogues 3‐O‐methyl‐D‐glucose and α‐methyl‐D‐glucoside were not metabolized in brain tissue.The uptake of these two sugars into the intracellular compartment of brain cortex slices was investigated using media with normal and low Na+concentration (replacement of all NaCl with choline Cl). The cellular transport was not Na+‐dependent. The transport mechanism clearly distinguished between the two sugars in both norma

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb12255.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—The chemical composition of four parts of the CNS (cerebrum, cerebellum, brain stem and spinal cord) was determined in 107 pigs at 11 stages of fetal and postnatal development and also in 6 adults. In cerebrum, cerebellum and brain stem, but not in spinal cord, the rate of increase in weight and the rates of change in lipid content slowed down for a period of about 10 days before and after birth. Cholesterol esters and desmosterol were only found in progressively decreasing amounts during the fetal stages of development and together with DNA these were exceptions to the general increases in the tissue concentrations and total amounts of other components during the period studied.The onset of myelination, as measured by calculated daily increases in tissue contents of cerebroside took place between 70 and 80 days conceptual age and there were two peaks of activity, the first occurring 2 weeks before and the second 3 weeks after birth. Unlike the rate curve for total spinal cord weight the biphasic accumulation of DNA was not synchronous with myelin lipid accretion and the earlier prenatal DNA peak probably denotes proliferation of oligodendrocytes. The two phases of myelination are discussed in relation to an observed generalized pause in development immediately before and after birth.Fatty acid analysis of cerebrosides indicated that, in spinal cord, chain elongation and desaturation are associated with myelination and continue with increasing activity until maturity. Consequently there was a progressive decrease in the proportion of saturated fatty acids. The fatty acid components of cholesterol esters in the developing pig were shown to be similar to those found during development in the CNS of other species but different from those found in demyelinating condition

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb12256.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—The effects of spermine and spermidine tetrahydrochloride on female Agus rat brain caudate nucleus homogenates, soluble acetylcholinesterase from the electric organ of Electrophorus electricus and acetylthiocholine iodide were studied. Measurements were made using an autoanalytical spectrophotometric method which measured the initial rate of reaction rapidly and accurately. Both polyamines interacted with the substrate, acetylthiocholine, causing an increase in the rate of its non‐enzymatic hydrolysis. Slight inhibitory effects on acetylcholinesterase were also observed. Combined effect of the polyamine on the substrate and the enzyme showed an inhibition at low and activation at high (above 1 mm) substrate concentrati

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb12257.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—The distribution of choline acetyltransferase (ChAT) and glutamate decarboxylase (GAD) in different layers of the pigeon optic tectum and in some nuclei of the optic lobe have been investigated. About 40% of GAD and 25% of ChAT were found in the superficial part of tectum, but negligible activity was found in the stratum opticum. The highest GAD activity was found in layers 3‐7 (according to the nomenclature of Cajal, 1911) with a peak in layer 4. ChAT activity peaked in layers 3, 5. 8 and 10/11. Its distribution correlated well with the staining pattern of AChE, particularly in the superficial part of the tectum. The distribution of ChAT and GAD did not change significantly 4 weeks after enucleation. ChAT and GAD activities were high in the nucleus isthmi, pars parvocellularis (Ipc). The activity of GAD was also high in the nucleus intercollicularis (ICo), the other nuclei showed less activity of both enzy

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb12258.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—Cerebral protein patterns resolved into 12 soluble fractions by ion exchange and 18 particulate fractions by gel electrophoresis were quantitatively analyzed from the cerebra of naive and trained pigeons. Behavioral treatment affected protein distribution significantly (P<0.01) in 2 soluble and 2 particulate fractions, and marginally (P<0.05) in a third fraction. The magnitude of the observed changes ranged from 12 to 57% of control values for a given fraction, but involved very small (<1 mg/g brain) shifts in absolute protein concentration. These results support the view that protein patterns are basically stable to non‐traumatic behavioral stimulation, but that small changes in specific fractions can oc

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb12259.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—The effect of L‐2,4 diaminobutyric acid (DABA) and β‐alanine on the K+stimulated release of [3H]GABA was examined using a continuous superfusion system in which a carrier mediated exchange diffusion could be demonstrated between [3H]GABA in preloaded rat cortical slices and unlabeled DABA and β‐alanine in the superfusion medium. These structurally related amino acids were chosen to investigate the source of releasable [3H]GABA because of evidence suggesting they may have differing affinities for the GABA carrier transport system that are specific for neurons and glia, DABA having a greater affinity for the neuronal GABA system and β‐alanine for the glial. Five millimolars‐DABA in the superfusion medium nearly abolished the K+stimulated release of [3H]GABA whereas β‐alanine had little effect. The results and conclusions are discussed in terms of a postulated carrier mediated exchange of unlabeled DABA with a specific neuronal pool of [3H]GABA interfering with the K+stimulated release of the radiolabeled GABA. The results provide indirect evidence in favor of a neuronal pool as the source of releasable [3H]GA

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb12260.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—The formation of a complex between myelin basic protein and S‐100 protein was detected from the change in migration of S‐100 protein on immunoelectrophoresis. A degree of specificity for the interaction was shown by two observations: (1) two other pure acidic proteins. III‐III‐2 and bovine serum albumin, did not show it and (2) complex formation was dependent on specific ions, either Ca2+(10 mM) or Mn2+(1 mM). Mg2+, Ba2+, and Li+had no effect. Non‐specific interactions between S‐100 protein and other basic molecules (histones. polylysine) are not dependent on specific ions such as Ca2+and Mn2+. The complex was stable at physiological salt concentrations and contained 3 mol of basic protein per mol of S‐100 protein. Complex formation was also detected from the alteration of migration rate of S‐100 protein in polyacrylamide gels. Serological activity (complement‐fixation) of S‐100 protein with anti‐S‐100 serum was redu

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb12261.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY