摘要:

Abstract—Cardiolipin (diphosphatidyl glycerol) was isolated from bovine brain grey matter in pure form by column chromatography. A combination of a DEAE cellulose column, an acid‐silicic acid column and a bicarbonate‐treated silicic acid column was used for the isolation. Analytical data on cardiolipin (and lyso‐cardiolipin), including phosphorus and fatty ester values, infrared and ultraviolet spectra, and chromatographic behaviour of intact cardiolipin, lyso‐cardiolipin and their water‐soluble hydrolysis products gave results which were consistent with the diphosphatidylglycerol structure proposed by MacFarlane. Cardiolipin constituted 1·2 per cent of the total lipids from grey matter, or 0·43 per cent of the dry weight. No aldehydes were detected in purified cardiolipin. The major fatty acids were 16:0, 16:1, 18:1, 18:2 and 20:4. Cardiolipin contained much higher concentrations of 18:2 (17·8 per cent) than any of the other major grey matter glycerophosphatides. Cardiolipin was hydrolysed by incubation with snake venom (Trimeresurus flavoviridis) phospholipase A (phosphatide acyl‐hydrolase, EC 3.1.1.4) to determine the distribution of fatty acids on the carbons of its diglyceride moieties. The fatty acids were not distributed randomly; 16:0, 18:0 and 18:2 were predominantly localized in theαandαpositions, while 18:1 and 20:4 were predominantly localized in

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb05920.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—1A procedure has been developed to measure ACh synthesis from [14C]‐precursors. As little as 10−9moles of ACh were detected as the result ofde novasynthesis. Following incubation of cortex slices of rat brain with eserine and a tagged metabolite, ACh carrier was added to the incubation medium and to an extract from the slices. ACh was purified by chromatography on Amberlite CG‐50, precipitation and recrystallization of ACh chloroaurate.2[U−14C]glucose and [2−14C]pyruvate formed similar amounts of [14C]ACh. Hydrolysis of ACh with subsequent chromatography of the resultant acetic acid demonstrated that all of the label was located in the acetyl moiety. [14C]acetate did not serve as a precursor of the acetyl group of ACh. Equivalent incorporation of carbons 1 and 6 of glucose into ACh indicated that glucose metabolism to ACh occurred via the Embden‐Meyerhof pathway.3The amount of ACh detected by bioassay after incubation of cortex slices with [U−14C]glucose was approximately the same as that calculated as labelled ACh; this demonstrates that all of the acetyl groups of ACh formed during incubation were derived from glucose.4[14C]choline, either methyl or chain labelled, formed [14C]ACh while labelled ethanolamine, serine and methionine did not. Synthesis from labelled choline did not occur in the absence of glucose.5When both [U−14C]glucose and [14C]choline were incubated with brain slices, the acetyl and choline moieties of ACh were equally labelled; this demonstrates that the entire molecule was formed from added precursors. Slices supported a high rate of ACh synthesis without addition of choline. The addition of 10−4m‐hemicholinium‐3 inhibited ACh formation by more than 90 per cent from either [U‐14C]glucose or [Me‐14C]choline.6Study of the time course of ACh synthesis from glucose demonstrated a rapid formation of [14C]ACh within the slices which reached a maximum during the first hour of incubation. [14C]ACh in the incubation medium accumulated at a linear rate for 3 hr. Replacement of a portion of the sodium chloride of the incubation medium by potassium chloride to a final concentration of 31 mm‐KCI markedly increased the formation of [14C]ACh found in the incubation medium. Decreased amounts of [14C]ACh were extracted from the slices by homogenization or by subsequent heating at pH 4 in

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb05921.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—Comparative studies were carried out on 5‐hydroxytryptamine (5‐HT) and 3,4‐dimethoxyphenylethylamine (DMPEA) oxidation using brain homogenates from different animals as the source of enzyme. Differences in the enzyme saturation curves, in the inhibitor spectra and variations of enzyme activity depending on the substrate used, suggested that the enzymes taking part in the oxidation of 5‐HT and of DMPEA slightly differ from each other. Differences were interpreted on the basis of the heterogeneity of monoamine oxidase (MAO), suggested by earlier investigations. Thus the possibility of an individual inhibition of the degradation of certain amines has to be c

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb05922.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—1The metabolism of three substrates, [U‐14C]glucose, [U‐14C]pyruvate and [U‐14C]glutamate has been studiedin vitroin neuronal and glial cell fractions obtained from rat cerebral cortex by a density gradient technique.2The mixed cell suspension, after washing, metabolized glucose and glutamate in a manner essentially similar to the tissue slice. Exceptions were a reduced ability to generate lactate from glucose and alanine from glutamate, and a lowered effect of added glucose in suppressing the production of aspartate from glutamate.3After 2 hr incubation with [U‐14C]glucose, the concentration of the amino acids glutamate, glutamine, GABA, aspartate and alanine were raised in the neuronal, compared to the glial fraction to 234 per cent, 176 per cent, 202 per cent, 167 per cent and 230 per cent respectively although both were lower than in the tissue slice. Incorporation of radio‐activity was absolutely lower in the neuronal fraction, however, and the specific activities of the amino acids were: glutamate 12 per cent, GABA 18 per cent, aspartate 34 per cent, and alanine 33 per cent of those in the glial fraction.4After the incubation with [U‐14C]pyruvate, the pool size of the amino acids were higher than after incubation with glucose, except for GABA, which was reduced to one‐third. The concentrations of the amino acids glutamate, glutamine, GABA, aspartate, and alanine in the neuronal fraction were respectively 46 per cent, 143 per cent, 105 per cent, 97 per cent, and 57 per cent of those in the glial. Thus, with the exception of alanine, the specific activity of the neuronal amino acids compared to the glial was little increased when pyruvate replaced glucose as substrate.5After 2 hr incubation with [U‐14C]glutamate in the presence of non‐radioactive glucose, the pool sizes of all the amino acids were increased in both neuronal and glial fractions, with the exception of neuronal alanine and glial glutamine. The concentrations of the amino acids glutamine, GABA, aspartate and alanine were raised in the neuronal fraction, compared to the glial, to 425 per cent, 187 per cent, 222 per cent, and 133 per cent respectively. The specific activities of all the amino acids were higher than with glucose alone with the exception of alanine, and neuronal GABA. Neuronal glutamine and aspartate had specific activities respectively 102 per cent and 84 per cent of glial.6An unidentified amino acid, with RFcomparable to that of alanine and specific activity close to that of glutamate, was also present after incubation. It was relatively concentrated in the neuronal fraction.7The distribution of the enzymes glutamate dehydrogenase, aspartate aminotransferase, glutamate decarboxylase and glutamine synthetase between the cell fractions was studied. With the exception of glutamine synthetase, none of the enzymes was lost from the cell fractions during their preparation. Only 14 per cent of the glutamine synthetase, compared with 75 per cent of total protein, was recovered in the fractions. Of the enzymes, glutamate dehydrogenase activity was 406 per cent, and glutamate synthetase activity 177 per cent in the neuronal fraction compared to the glial in the absence of detergent. In the presence of detergent, glutamate dehydrogenase control was 261 per cent, aspartate aminotransferase activity 237 per cent is the neuronal as compared to the glial fraction.8Incorporation of radioactivity into acid‐insoluble material from either glutamate or pyruvate was twice as high into the neuronal as the glial fraction.9The extent to which these differences may be extrapolated back to the intact tissue is considered, and certain correction factors calculated. The significance of the observations for an understanding of the compartmentation of amino acid pools and metabolism in the brain, and the possible identification of such compa

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb05923.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—The distribution of tryptophan hydroxylase in the cat brain was investigated and found to parallel roughly the distribution of serotonin. The most active areas are the caudate nucleus, septal area, anterior perforating substance, hypothalamus, amygdala and various areas of the midbrai

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb05924.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—Myelinated cerebellar tissue culture (organ culture) was used to assess the salvage andde novopathways of pyrimidine synthesis in mammalian brain. Radioactive orotic acid and carbamyl aspartic acid were readily incorporated into UMP and into perchloric acid‐insoluble RNA. The incorporation was effectively blocked by azauridine. Neither radioactive sodium bicarbonate or citrulline was incorporated into UMP or blocked by azauridine. [3H]Uridine, on the other hand, rapidly entered the cultures, was incorporated into UMP and perchloric acid‐insoluble material, and was partially inhibited by azauridine. The failure to demonstrate activity of carbamyl phosphate synthetase suggests the potential importance of the salvage pathway and the likely dependence of the brain upon exogenous and endogenous pyrimidine precu

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb05925.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—The cholinesterase activity of motor endplates in tibialis anterior muscle of rats accounted for about 20 per cent of the total cholinesterase activity of the muscle. In the isolated muscle membrane preparation of rat intercostal muscle, the cholinesterase activity was localized solely in the motor endplate, as shown by cholinesterase staining. The cholinesterase activity of the membrane per unit of nitrogen was 26·9 times that of the muscle homogenate. The membrane (endplate) cholinesterase had an optimal pH of 8,Kmvalue of 3·1 mm, and was stable at 4° for at least 13 days. Cholinesterase of a motor endplate hydrolysed 2·69 × 108acetylcholine molecules in 1 msec. Since it is estimated that 108cholinesterase active sites are present in a motor endplate, the turnover time (time necessary for one enzyme site to hydrolyse one acetylcholine molecule) is calculated to be 372μsec, and the turnover number (molecules of acetylcholine hydrolysed by one enzyme site/min) to be 1·61 × 105. From studies with cholinesterase inhibitors, cholinesterase activity was estimated to be due mostly to acetylcholinesterase, and only a minor part to pseudocholinesterase. The muscle membrane preparation seems to be useful for the study of other properties of the motor

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb05926.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—Twenty‐nine autopsy specimens of intracerebral tumours (nine astrocytomata, ten medulloblastomata and ten glioblastomata multiforme), as well as samples of peritumoral and apparently normal brain tissue, have been studied for Na, K, P, Ca, Mg, Cu, and S contents.The tumour tissue, irrespective of the histological characteristics, as compared to the ‘normal’ and perineoplastic tissues, showed higher concentration of Ca, Mg, Cu and S. The peritumoral tissue, regardless of the tumour type, showed a higher concentration of Cu than the ‘normal’ control brain.The more malignant glioblatomata and medulloblastomata. The Cu levels did not show a significan

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb05927.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—A total of ten electroshock seizures (two seizures per day) were induced in rats beginning 3 days after an injection of [U‐14C]glucose. Despite the intense stimulation, the labelling of the protein and nucleic acid fractions in the brains of convulsed animals decreased only slightly and not significantly. During the first 2 days after administration of [14C]glucose to untreated animals, there was a slight decrease in the specific activity of protein‐bound glutamic acid relative to that of aspartic acid and the total protein fraction, suggesting the presence of a protein with a high content of glutamic acid and a rapid tur

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb05928.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb05929.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY