摘要:

Abstract—By techniques of isosmotic density gradient ultracentrifugation three subfractions of myelin were isolated from homogenates of whole rat brain at densities of 1.054 g/ml (myelin I), 1.060 g/ml (myelin II) and 1.066 g/ml (myelin III). The stability of these fractions was demonstrated by the zonal centrifuge profile analysis of recycled fractions. Examination of the three myelin subfractions by techniques of electron microscopy and thin layer chromatography detected no obvious morphological or chemical differences. However, analysis for protein, cholesterol, phospholipids and cerebrosides did reveal differences among myelin I, myelin II and myelin III. Myelin I contained relatively more cholesterol than II or III. Myelin III contained relatively more phospholipids than I or II. The cerebroside‐to‐protein ratios were the same in all three fractions. Quantitative differences in fatty acid composition (as detected by gas‐liquid chromatography) were also o

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01472.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—The influence of the following acetylenic analogues of GABA on GABA‐metabolizing enzymes was studiedin vitro: 4‐amino‐, 4‐morpholino‐, 4‐piperazino‐, 4‐piperidino‐ and 4‐pyrrolidinotetrolic acid. 4‐Aminotetrolic acid was a linear competitive inhibitor of GABA transaminase activity in extracts of rat cerebral mitochondria and a linear noncompetitive inhibitor of this enzyme activity in extracts ofP. fluorescenswhen activity was measured with GABA as the variable substrate. From these results it was calculated that the dissociation constants for the binding of 4‐aminotetrolic acid to the pyridoxal form of these enzymes are approx. 1 mM. The other substituted tetrolic acids did not influence either transaminase activity under the conditions studied. None of the substituted tetrolic acids influenced the L‐glutamic acid decarboxylase activity in extracts of rat ce

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01473.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—trans‐4‐aminocrotonic acid,dl‐cis‐aminocyclohexane‐ltarboxylic acid and 4‐aminotetrolic acid were found to be competitive inhibitors of GABA uptake in rat brain slices. These inhibitors are analogues of extended conformations of GABA, which indicates that these conformations are important in the initial binding of this inhibitory transmitter to its tran

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01474.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—Essential fatty acid deficiency initiated in rats prior to birth and continued for 140 days after birth affects the fatty acid composition of ethanolamine phosphoglyceride of brain subcellular fractions (myelin, microsomes, mitochondria and synaptosomes). It was confirmed that the fatty acid composition of the same phospholipid class differs considerably among the various subcellular fractions: myelin has the highest concentration of long‐chain monoenes, while in the other fractions saturates and polyenes predominate. In EFA deficiency it was found that (1) trienes are elevated and tetraenes decreased in all fractions, (2) the triene/tetraene ratio, which is considered a biochemical index of essential fatty acid deficiency, is highest in myelin and lowest in the synaptosomal fraction, and (3) in all fractions there is a shift towards more unsaturated members of the same fatty acid fam

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01475.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—DNA has been extracted from normal and scrapie affected mouse brain fractions, 48 h after the injection of [3H]thymidine precursors. The extracted DNA has been subjected to fractionation on hydroxyapatite columns and CsCl gradients. The specific activity of double stranded nuclear DNA is two to three times higher when extracted from scrapie‐affected brain than from normal brain, but there is no apparent difference in the number of counts associated with double stranded mitochondrial DNA extracted from similar numbers of normal and scrapie affected brains. DNA from the large granule fraction of scrapie affected brain contains a peak of counts, melting off hydroxyapatite columns before the double stranded peak, consistent with the presence in scrapie brain of trace amounts of a small single stranded

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01476.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—Severe vitamin B6deficiency induced in pregnant rats during the last 2 weeks of gestation resulted in a reduction of brain weight in the new born rat. This indicates that the foetus was affectedin utero. However, no significant changes were observed in other measured parameters in brains of the neonates at birth. Subjecting these neonates to vitamin B6 deficiency during lactation severely retarded the development of their body and brain weights. There is evidence to suggest that B6deficiency also leads to increased levels of glutamic acid decarboxylase apoenzyme, although thein vivoactivity of the enzyme appears to be reduced as a result of marked reduction in coenzyme saturation. The level of γ‐aminobutyric acid transaminase apoenzyme was reduced. Its coenzyme saturation was also reduced, but the level of reduction was less than with the decarboxylase. The progressive increase in whole brain γ‐aminobutyric acid level was also retarded by the deficiency. Five days after administration of pyridoxine hydrochloride to 2‐week‐old deficient neonates, whole brain γ‐aminobutyric acid levels and the activities of whole brain glutamic acid decarboxylase and γ‐aminobutyric acid transaminase were almost restored to normal. However, brain and body weight showed a slow recovery during the same period. It was found that in the recovering neonates both enzymes follow changes in age rather than change

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01477.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—Microsomal, mitochondrial, synaptosomal and synaptic vesicle fractions of rat brain took up [3H‐methyl]choline by a similar carrier‐mediated transport system. The apparentKmfor the uptake of [3H‐methyl]choline in these subcellular fractions was about 5 × 10−5M. Choline uptake was also observed in microsomal fractions prepared from liver and skeletal muscle. Virtually identical kinetic properties for [3H‐methyl]choline transport were found in the synaptosomal fractions prepared from the whole brain, cerebellum or basal ganglia. Countertransport of [3H‐methyl]choline from the synaptosomal fraction was demonstrated against a concentration gradient. HC‐3 was a competitive inhibitor of the uptake of [3H‐methyl]choline in brain microsomal, synaptosomal and mitochondria]fractions with respective values forKiof 4.0, 2.1 and 2.3 × 10−5M. HC‐15 was a competitive inhibitor of the transport of [3H‐methyl]choline in the synaptosomal fraction, with aKiof 1.7 × 10−4M. Upon entry into the microsomal fraction, 74 per cent of the radioactivity could be recovered as unaltered choline, 10 per cent as phosphorylcholine, 1.5 per cent as acetylcholine and 2.5 per cent as phospholipid.Choline acetyltransferase (EC 2.3.1.6) was assayed with [14C]acetylCoA in synaptosomal fractions prepared from basal ganglia and cerebellum, and in the 31,000gsupernatant fraction of a rat brain homogenate. Enzyme activity was 11‐fold greater in the synaptosomal fraction from the basal ganglia than in that from the cerebellum. HC‐3 did not inhibit choline acetyltransferase and there was no evidence for acetylation of HC‐3.Our findings suggest that choline uptake is a ubiquitous property of membranes in the CNS and cannot serve to distinguish cholinergic nerve e

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01478.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—Two glycolipids, accumulated in the spinal ganglia of a patient with Fabry's disease were identified as: galactosyl (α1 → 4) galactosyl (β1 → 4) glucosyl(1 → 1) ceramide (CTH) and galactosyl (α1 → 4) galactosyl(1 → 1) ceramide (CDG). Only one glycolipid which had the same structure as the CTH in the spinal ganglia accumulated in the sympathetic ganglia of the patient. In the nervous system, CTH contained behenic acid (C22:0) as the major fatty acid. In the spinal ganglia, CDG also contained behenic acid as the ma

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01479.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—The ontogenetic development of norepinephrine and dopamine and their associated biosynthetic and degradative enzymes was investigated in five anatomical regions of the rat brain. Clear regional differences were found in the development of both norepinephrine and tyrosine hydroxylase (EC 1.14.3.1). In the case of both norepinephrine and tyrosine hydroxylase, brainstem structures achieved adult levels well before forebrain structures. The development of DOPA decarboxylase (EC 4.1.1.26), monoamine oxidase (EC 1.4.3.4) and catechol‐0‐methyl transferase (EC 2.1.1.6) did not appear to differmarkedly from area to area. Further analysis of the data revealed that in forebrain structures both the amines and the biosynthetic enzymes developed concurrently. By contrast, in the brainstem structures, there was a dissociation of amine and enzyme development with development of tyrosine hydroxylase, in particular, markedly preceding that of norepinephrine and of DOPA decarboxylase. The bases for both the lower amine levels in the infant brain and the regional developmental differences are discussed in relation to the anatomical organization of the central catecholamine‐containing

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01480.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—Myelin from the peripheral nervous system has been shown to contain two basic protein components and an electrophoretically slower‐moving major protein, the ‘J’ band. The ‘J’ band protein cannot be selectively removed by aqueous or organic solvents and does not correspond to proteolipid or acidic protein. Histochemical stains applied to peripheral nervous systems myelin proteins separated by polyacrylamide electrophoresis indicate that ‘J’ band protein is analogous with the neurokeratin of the nerve sheath. Trypanophilia observed histochemically in unfixed myelin is principally due to basic proteins. With prolonged tryptic digestion ‘J’ band protein is degraded. Thus, previous classifications of myelin proteins based on trypsin sensitivity have been modified. All peripheral nervous system myelin proteins should be regarded as trypsin‐sensitive, the basic protein being relatively more and the ‘J’ band protein re

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01481.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY