摘要:

Abstract—An assay system for the measurement of triphosphoinositide phosphodiesterase in homogenates of rat brain is described. With triphosphoinositide (TPI) as substrate, and in the presence of 0·1m‐KCI and saturating amounts of diethyl ether, the activity of phosphodiesterase in myelinated brain was 400–500 μmoles of TPI hydrolysed per g wet wt. per hr. One quarter of the adult level of the enzyme was present in rat brain one day after birth, with the remainder being added prior to and during the early stages of myelination. On subfractionation of brain homogenates, substantial activity of the enzyme was located in the soluble portion and in the paniculate fractions enriched in myelin and synaptosomes. The enzyme associated with the particulate fractions could not be detached from the membranes by any of several methods employed. There was a rough correlation between distribution of phosphodiesterase and that of 5′‐nucleotidase, an enzyme associated with plasma membrane in a number of tissues. Some implications of the results ar

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb00495.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—Rapid administration (0·4 ml in 1 sec) of the convulsant inhalant, flurothyl (hexafluorodiethyl ether, indoklon), to mice induced within 10 sec clonic‐tonic seizures that were accompanied by marked decrease of P‐creatine, decrease of ATP and glucose, and increase of lactate in the cerebral cortex. In contrast, mice to which flurothyl had been administered slowly (0·05 ml every 30 sec for 10 min) exhibited myoclonic jerks after about 3 min, merging into irregular clonus at about 5 min, and intermittent clonus thereafter until onset of tonic hind limb extension at about 10 min. In these mice, P‐creatine in cerebral cortex decreased gradually for 6 min and then remained through 10 min at levels nearly as low as those reached 10 sec after rapidly administered flurothyl. Lactate in cerebral cortex increased much more during the 10 min of slow administration of flurothyl than in 10 sec of rapid administration, the greatest increase occurring at 4–6 min, as myoclonic jerks merged into irregular clonus. Glucose and ATP in cerebral cortex fluctuated somewhat but did not decrease greatly when flurothyl was administ

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb00496.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—The isolation and identification of the following gamma‐glutamyl peptides from the brain ofMacaca irusandCercopithecus ethiopsis reported: glutamyl‐glutamine, glutamyl‐glycine, glutamyl‐alanine, glutamyl‐valine, glutamyl‐isoleucine, glutamyl‐glutamate, glutamyl‐serine and glutam

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb00497.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—The effect of excess leucine in the diet on serotonin metabolism in the brain was investigated in experimental animals. It was found that:(1) Animals receiving diets containing 3 % and 8 % leucine and those receiving jowar diets had significantly lower levels of serotonin in the brain.(2) Intraperitoneal administration of the precursor amino acid 5‐HTP increased the serotonin concentration in brain in both control and leucine‐fed animals. However, the serotonin concentration in leucine‐fed animals was significantly lower than that of pairfed controls. Larger amounts of the synthesized serotonin were found to be catabolized in 3 hr in leucine‐fed animals than in control animals.(3) Thein vitrouptake of [14C]5‐HTP by brain slices of animals fed leucine was found to be similar to that of control animals.(4) The basal concentration of 5‐HIAA in brain was higher in leucine‐fed animals, suggesting a higher rate of catabolism of serotonin.(5) Administration of nicotinic acid resulted in a further fall of serotonin concentration in the brains of leucine‐fed animals but not i

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb00498.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—Isolated brains from three adult monkeys were perfused for 1 hr with [2‐14C]glucose. Glycogen was isolated from the brain stem, cerebral hemispheres, cerebellum and the hypothalamic area at completion of the perfusions. The distribution of14C in carbons of the glucose unit of glycogen was determined and from this the contribution of the pentose cycle to metabolism of glucose was calculated. The data indicate a maximum contribution by the pentose cycle of 5–8 per cent in brain. No significant difference was observed in the various portions of brain. Oxygen consumption was noted to be low in relation to the amount of glucose utilized, as measured in these experi

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb00499.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—A reproducible extraction and fractionation scheme for the isolation of peptides from nervous tissue is described. The low molecular weight fraction, obtained by this procedure from calf brain stem tissue, was further investigated. The presence ofN‐acetyl‐aspartic acid,N‐acetyl‐α‐aspartylglutamic acid and pyrrolidone‐2‐carboxylic acid was confirmed. The occurrence of minor quantities of glutamylpeptides, identical with or related to known γ‐glutamyldipeptides and glutathione, was indicated.Three hitherto unknown dipeptides α‐aspartylserine, alanylphenylalanine and isoleucylleucine were identified. Mass spectrometry was used in the fi

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb00500.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—The proximo‐distal gradients for representative peptidases, peptidylpeptide hydrolases, and amino acids were measured in segments of peripheral nerve from invertebrates and vertebrates and in the lobster brain and ventral cord.Crustacean nerve was characterized by a large pool of free amino acids totaling 100–200 μmoles/g wet wt. In lobster nerve, the principal free amino acid was aspartic acid which comprised 55 per cent of the free pool, whereas in the rat sciatic nerve it comprised only 5 per cent. The principal free amino acid in rat sciatic nerve was taurine (32 per cent of the pool) and in lobster brain glycine comprised 30 per cent of the pool. No consistent patterns emerged for the gradients along the nerves for amino acids and hydrolytic enzymes. In the leg nerve of the lobster, concentrations of aspartic acid and arginine were higher in the proximal region, and concentrations of proline and alanine were higher in the distal region. Concentrations of most amino acids were higher in the proximal regions of crab nerve, of lobster brain and ventral cord, and of rat sciatic nerve.Rat sciatic nerve exhibited a pronounced proximo‐distal increase in activity of aminopeptidase (Leu‐Gly‐Gly). In lobster leg nerve, activity of neutral proteinase was higher in the proximal segment, whereas activity of acid proteinase was higher in the distal segment. The best examples of proximo‐distal gradients were found in lobster brain and ventral cord; activities of endopeptidases, arylamidases (Leu‐ and Arg‐βNA), and aminopeptidase were higher in the supra‐esophageal ganglia or cephalothorax segments than

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb00501.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—Creatine kinase derived from rabbit brain has been re‐examined with respect to its kinetic features. The enzyme from brain has lower Michaelis constants for both ADP and creatine phosphate than does the enzyme from rabbit muscle. Substrate inhibition by excess creatine phosphate occurs at a concentration approximating that found in the tissue. The enzyme from muscle is less sensitive to substrate inhibition.The crude mitochondrial fraction from rat brain was centrifuged in a sucrose density gradient and the distribution of enzymatic activities among the subfractions was determined. The distribution of creatine kinase resembled that of two glycolytic enzymes; no evidence for a mitochondrial localization was fo

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb00502.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—The composition of sphingolipids and phospholipids of mouse brain during myelination was determined in normal animals and in mice with a genetically‐determined disorder of myelin formation. Myelination was normally characterized by a two‐fold increase in total phospholipids of brain, a four‐fold increase in total sphingolipids, and a six‐fold increase in cerebrosides. The Jimpy mutant, with defective formation of myelin in the central nervous system, demonstrated a marked deficiency of cerebrosides and a significantly lower content of total sphingolipids, without alteration of the composition of phospholipids. The increasing content of cerebrosides in the brains of the leucodystrophic mutant at the time in development when myelination is most active and the subsequent relative deficit suggest that the failure of myelin formation is not the result of a defect in biosynthesis of cer

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb00503.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—A study has been made of the fatty acyl profiles of lecithin in subcellular fractions of the brain in rat, guinea pig and rabbit. It was found that cerebral lecithins consisted of at least two groups with dissimilar fatty acyl profiles. The group obtained from myelin showed little variation with age of the rats or among two other species examined. The changes in lecithin fatty acyl composition of brain homogenates were in agreement with a progressively greater contribution of myelin lecithins to brain homogenate lecithins with increasing ag

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb00504.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY