摘要:

Abstract—The effect of 100% O2at one atmosphere on carbohydrate metabolism in cell‐free homogenates of rat brain was studied under different experimental conditions. The principal findings were the following:1Compared to 10% O2‐90% N2, oxygen at one atmosphere inhibited metabolism of α‐oxoglutarate and depressed the net synthesis of ATP. With glucose as substrate, accumulation of ATP was also markedly inhibited but substrate utilization was only slightly affected.2Glycolysis in brain was relatively resistant to oxygen toxicity, except in the presence of added Cu2+.3With α‐oxoglutarate as the substrate, inhibition of the formation of ATP occurred earlier than inhibition of substrate utilization, indicating the particular sensitivity of oxidative phosphorylation to inactivation by oxygenin vitro.4Cu2+and Fe2+accentuated oxygen toxicity but appeared to act by different mechanisms. Co2+exerted a protective effect.5The sulphydryl compounds, dithiothreitol and reduced glutathione, strongly diminished the toxic effec

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb03341.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—Rat brain polysomes were prepared from a deoxycholate‐treated postmito‐chondrial supernatant in the presence of 2% bentonite and 1 mg/ml of yeast RNA to prevent partial degradation during preparation.1The polysomal preparations had an absorption maximum at 260 mμ and an absorption minimum at 235 mμ. The ratio of absorption maximum to minimum and the RNA to protein ratio were 1·58 and 1·06 respectively in 6‐day‐old rat brain polysomes. The sedimentation patterns showed six distinct peaks with sedimentation coefficients of 235S, 185S, 173S, 135S, 100Sand 80S, indicating that these preparations have the characteristics of pure heavy polysomes.2The rate of [14C]phenylalanine incorporation into brain polysomal protein was maximal at approximately 10 days of age and decreased thereafter. A similar progressive reduction with increasing age was found in the stimulation of phenylalanine incorporation by the addition of 60 μg/tube of polyuridylic acid. However, the incorporation of phenylalanine into young rat brain polysomes was usually greater even with the addition of polyuridylic acid than in the older animals.3The comparative studies on sucrose density gradient centrifugation of polysomes between young and adult rat brains showed a considerable decrease of heavy polysomes in the older animals.4The effect of various factors on the stability of brain polysomes from both ages has been studied. The rates of RNA, protein and acid‐soluble phosphorus release from polysomes of the adult rat brains were usually greater in the presence of high salt concentration, ethylenediaminetetra‐acetic acid and urea than those from the corresponding preparations of younger animals. On the basis of evidence obtained from the above results it suggested that the adult brain polysomes were more unstable than those of younger animals.5The amount of polysomal RNA linearly increased up to the first 20 days after birth and then levelled off. The ratio of G + C/A + U of polysomal RNA was less in the young rat brains, falling to 1·30 as compared to 1·50 in older animals. The differences were statistically significant at less than a 1% level of confidence.6Polysomal preparations also contained RNase, phosphomonoesterase, phospho‐diesterase and 5′‐nucleotidase activities which cannot be washed off. The specific activities of these enzymes were generally higher in young rat brai

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb03342.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—In rabbits, the sedative effect of chlorpromazine (CPZ) is temporally correlated with a decrease in dopamine and a rise in homovanillic acid (HVA) in the basal ganglia. Reserpine elicits similar biochemical changes. In addition, both reserpine and CPZ reduce the concentration of 3‐methoxytyramine, theO‐methylated metabolite of dopamine in the basal ganglia of normal rabbits. In contrast, both drugs markedly increase the levels of this metabolite in animals treated with a monpamine oxidase inhibitor. The results indicate that CPZ, like reserpine, causes an intraneuronal destruction of dopamine, and suggest that the well‐documented increase in dopamine synthesis after CPZ is the consequence of this mechanism and not of a blockade by CPZ of the dopaminergic receptors i

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb03343.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—The quantitative histochemistry of acetylcholinesterase (AChE) has been examined in hippocampus (regio superior) and area dentata. Samples (0–05–2 μg) were dissected from freeze‐dried tissue sections and assayed by either a colorimetric or a radiometric micromethod. In hippocampus the highest AChE activity occurred in a narrow zone just beneath the layer of pyramidal cells. Stratum oriens had a higher activity than stratum radiatum. A small peak of activity occurred in the lacunosal layer. In area dentata the overall activity was about 60 per cent higher than in the hippocampus. The highest activities were found in two zones adjacent to the granular layer.When the results were expressed as activities per volume of tissue they correlated well with microdensitometric measurements on sections stained for AChE by the Koelle method.Following transection of the fimbria the activity decreased to a low level, approaching a common value in the layers examined.The results are discussed in relation to the significance of AChE in the hippocampa

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb03344.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—Ribosomal aggregates were isolated from rat brain stem and characterized as polysomes by sedimentation analysis and by their sensitivity to RNase and EDTA treatment.Three weeks following hypophysectomy there was a significant decrease in the content of large polysomes in the rat brain stem. The incorporation of radioactive uridine into RNA was studied using a double‐labelling technique with [3H]‐ and [14C]uridine and labelling periods of 70 and 180 min. It was found that after hypophysectomy the incorporation of radioactive uridine into total, nuclear and cytoplasmic RNA and in polysomes was decreased after 70 and 180 min. Information on the nature of the rapidly‐labelled RNA in the various subcellular fractions was obtained by sucrose gradient sedimentation analysis.After 70 min of labelling the nucleus contained heterogeneous RNA with a considerable fraction of RNA sedimenting faster than 28S.In the cytoplasmic fraction heterogeneous 4 to 30SRNA was found, presumably associated with RNP particles, whereas after 180 min the polyribosomal aggregates were also labelled.The present results indicate a profound effect of hypophysectomy on the metabolism of all species of brain RNA inves

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb03345.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—The folate coenzymes of mouse brain underwent quantitative and qualitative changes during the first few weeks after birth. The total folate coenzymes per unit wet weight declined by approximately 60 per cent. In the newborn brains a relatively small proportion of the total folates were poly‐γ‐glutamyl derivatives, but the percentage of the total folates in these forms increased as the brain m

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb03346.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—The presence and distribution of RNA in nerve fibres was studied by autoradiographic detection of [3H]uridine incorporation in chick embryo sensory nerve cells culturedin vitrounder the effect of the Nerve Growth Factor. The presence of RNA in these fibres, free from satellite cells, is demonstrated. The cellular origin of the fibre RNA is, at least in part, prove

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb03347.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—Sialoglycoproteins and gangliosides were characterized in various bovine brain regions by determining the amount of sialic acid. Expressed per g dry weight, the gangliosidic sialic acid ranged from 11·20 to 1·93 μmol and the glycoprotein sialic acid from 8·93 to 1·84 μmol in grey and white matter respectively (values not corrected for incomplete release and breakdown during hydrolysis). Both the sialoglycoproteins and the gangliosides occur in highest concentration in areas predominating in neuronal cell bodies (cerebral grey, cerebellar grey, caudate nucleus). The lowest concentrations are found in those areas, consisting largely of myelinated fibre tracts and glial cells (pons, medulla, corpus callosum, cerebral white). Relative to the gangliosides the sialoglycoproteins are somewhat more concentrated in white matter.The sialidase activity was investigated with endogenous substrate as well as with additional gangliosides or sialoglycopeptides. In all conditions the activity was much greater in grey matter than in white matter. The regional sialidase distribution more or less parallels the distribution of sialic acid in the various regions. At high substrate level the sialoglycopeptides inhibit the sialidase activity. There are indications that gangliosides are a far better substrate for brain sialidase than glycoproteins or glycopeptides. The possible significance of this phenomenon is di

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb03348.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—1Guinea pig neocortical tissues incubated in glucose‐bicarbonate media reached stable calcium contents of 2 μat./g of which 0‐35 μat.Ca/g was in a space accessible to inulin.2Addition ofl‐glutamate salts caused a prompt increase in intracellular calcium at rates up to 7 μat./g tissue/hr.3Using45Ca, this increase was found to be due to an accelerated influx of Ca and a diminished efflux. The rate of influx could be doubled by 1 mm‐l‐glutamate.4Tetrodotoxin at concentrations of 66‐330 nM diminished45Ca entry, both in the absence and presence of added glutamate.5Tissue sodium and potassium contents are also reported under some conditions, and the extent to which calcium may condition sodium and potassium moveme

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb03349.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—Paper chromatography of extracts from mesenteric Pacinian corpuscles of the cat revealed the presence of glutamic acid, glutamine, aspartic acid and alanine as major amino acids, and glycine, serine and threonine in traces; GABA was not detected. Levels of glutamic acid (0·75 μmol/g ′ 0·37,s.d.), glutamine (1·34 ± 0·55), and aspartic acid (0·32 ± 0·22) of mesenteric and pancreatic samples of Pacinian corpuscles were determined by separation on chromatographic columns. The protein values averaged 5·2 ± 0·66 per cant of the wet weight.Treatment of the cats with reserpine or pargyline or deafferentation of the Pacinian corpuscles did not significantly alt

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb03350.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY