摘要:

Abstract—Methods are presented for the measurement of the non‐oxidative enzymes of the pentose phosphate pathway in freeze‐dried samples of tissue weighing 2 μg or less. The activities of transketolase (EC 2.2.1.1), transaldolase (EC 2.2.1.2), ribosephosphate isomerase (EC 5.3.1.6), and ribulosephosphate epimerase (EC 5.1.3.1), together with glucose‐6‐phosphate dehydrogenase (EC 1.1.1.49) and 6‐phosphogluconate dehydrogenase (EC 1.1.1.44) have been measured in seven specific regions in the central nervous system of the rat. Michaelis constants and temperature coefficients of these enzymes were obtained on homogenates of whole rat brain. The entire enzymic complement of the pentose phosphate pathway was detected in each of the regions examined. The activities of the non‐oxidative enzymes and 6‐phosphogluconate dehydrogenase did not vary greatly among the different regions examined, whereas the activity of glucose‐6‐phosphate dehydrogenase varied in close correspondence with the lipid content of the various structures. The cellular, granular layer of the cerebellum was exceptional, since it exhibited at least three times more transaldolase activity than that observed in other structures, an observation suggesting an association of transaldolase wi

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01247.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—Explants of rat cerebellum obtained 12‐24 h after birth were maintained in culture in Maximow assemblies. About 90 per cent of the cultures myelinated after 10–12 daysin vitro. Cultures maintained for varying periods of time were exposed to [35S]Na2SO4; labelled sulphatide was recovered from the total homogenate. Preparation of a subcellular fraction with density properties corresponding to those of myelin indicated that labelled sulphatide appeared in this fraction. Cultures which were poorly‐myelinated always exhibited a lower rate of inccrpomtion than well‐myelmated cultures from littermate animals, but the distribution of labelled sulphatide into the ‘myelin’ fraction was similar in the two groups. The rate of incorporation of [35S]Na2SO4into total sulphatide increased with the duration of the culture, with a low level of incorporation until the seventh dayin vitro, followed by a sharp increase in rate up to the 21st day. This pattern resembles that observed for rat cere

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01248.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—1In vitroincorporation of tritiated leucine into nuclear proteins of normal human brain, astrocytoma I and II and glioblastoma multiforme was investigated. The distribution of radioactivity among various protein fractions of nuclei was determined.2The results demonstrate that the isolated nuclei of astrocytoma I and II incorporate radioactivity into proteins at least 40 times more actively than nuclei of normal human brain or glioblastoma multiforme.3The residual protein fraction was the most highly labelled fraction among the nuclear pioteins. This fraction from astrocytomas incorporates relatively more radioactivity than the similar fraction of normal human brain or glioblastoma multiforme. The buffered‐saline soluble protein fraction of astrocytoma nuclei contained a relatively lower amount of radioactivity than the similar fraction of normal human brain or glioblastoma multiforme. The total radioactivity incorporated into the deoxyribonucleoproteins seemed to increase with the malignancy of the tissue investigated. The significance of the results with respect to malignant transformation is discus

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01249.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—Further investigations have been made into ergothioneine in the brains of several mammalian species, and the distribution of ergothioneine in the brain of the ox is described. It has not been possible to confirm many of the findings of earlier workers and the results do not appear to support their conclusion that ergothioneine is identical with the cerebellar facto

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01250.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—Two enzymes that selectively hydrolyse kinins at pH 7.5 were obtained in partially purified form from the supernatant fraction of homogenates of previously frozen rabbit brain by gel filtration on Sephadex G‐100. The enzymes were detected and their activity estimated by bioassay with the isolated guinea pig ileum The products of the enzymic reactions were identified by high voltage electrophoresis at pH 3.5 and by the determination with the amino acid analyser of the amino acids released from the kinins.One enzyme, kinin‐converting enzyme, catalyses the hydrolysis of kinin‐10 (Lysbradykinin) and kinin‐11 (Met‐Lys‐bradykinin) into kinin‐9 (bradykinin). It also hydrolyses the aminoacyl‐8‐naphthylamides of methionine, lysine, arginine and leucine. The conversion of kinin‐10 to kinin‐9 was inhibited by puromycin (Ki3.5 × 10−5M) These properties are similar to those of brain arylamidases described in the literature.Kininase, the second enzyme, inactives kinins 9, 10 and 11 by peptide‐bond hydrolysis. Similar rates of release of arginine and phenylalanine were observed for the three kinins, suggesting that kininase acts at the carboxy‐terminus of these peptides.Our results suggest that brain contains proteases which apparently selectively metabolize polypeptide hormones that exert definite pharmacological effects on the central

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01251.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—Free choline and acetylcholine (ACh) in mouse or rat brain were assayed biologically. The subcellular distribution of ACh in brain slices that had been incubated in the presence of eserine was compared to that in control brain; during incubation, the ACh outside nerve endings increased four‐fold, the ACh released from synaptosomes by osmotic shock doubled but the ACh bound firmly within nerve endings did not increase. The two nerve ending stores of ACh were labelled to similar specific radioactivities when slices were incubated with [3H]choline, but the specific radioactivity of the ACh formed was much lower than that of the added choline. Tissue incubated in the presence of eserine released choline and ACh into the medium and the tissue levels of both substances increased. Brain tissue exposed to Na+‐free medium lost 84 per cent of its ACh and 66 per cent of its free choline; the amounts of both substances returned towards control values during subsequent incubation in a normal‐Na+medium (choline‐free). Both the ACh outside nerve endings and the ACh associated with synaptosomes were depleted when tissue was incubated in Na+‐

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01252.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—Existing methods for the colorimetric (diphenylamine) determination of DNA content of brain have been modified for preserved cerebral hemispheres. On the average, right and left hemispheres (rat and chicken) contained similar amounts of DNA and one hemisphere could serve as a control for the other. All comparisons have been made with the values obtained for frozen brains (‘controls’). Preservation in 10 % (v/v) buffered formalin for 1 month introduced significant differences for both neonatal and adult cerebral hemispheres. On the other hand, preservation in 75 % (v/v) aqueous ethanol for 1 month did not introduce any significant differences in any of these determinations. Embedding in paraffin and subsequent clarification (removal of paraffin) did not further affect the DNA values of cerebral hemispheres preserved in formalin. Consequently it was possible to determine DNA in histological sections at the desired planes or even in parts of the sections. Micro‐modifications have been devised to determine colorimetrically the total DNA content of small brains (e.g. tadpoles) or of small parts of larger brains, as low as 25 μg of DN

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01253.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—Levels of free amino acids, profiles of polyribosomes, and rates of protein synthesis and degradation were examined in the brains of chicks fed toxic levels of galactose. The content of a number of amino acids were altered; alanine and leucine were most strikingly depressed, whereas levels of aspartate were elevated. Polyribosomal profiles were unaltered. There appeared to be no detrimental effect on protein synthesis as judged byin vivoincorporation of L‐[U‐14C]leucine and L‐[guanidino‐14C]arginine. Likewise, the half‐lives of proteins, measured by the loss of L‐[guanidino‐14C]arginine, were similar in experimental and control groups. In contrast, initial rates of incorporation of [3H]glucosamine into glycoproteins were enhanced. The effect was greatest in the microsomal fraction and typically 50 per cent greater than controls. Levels of free glucosamine and protein‐bound hexosamine were essentially unaltered in the gal

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01254.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—The isomeric phenolic acids, homovanillic acid (4‐hydroxy,3‐methoxyphenylacetic acid) and homo‐iso‐vanillic acid (3‐hydroxy,4‐methoxyphenylacetic acid), were separated and identified by means of paper chromatography of their azo‐derivatives with diazotized para‐nitroaniline. Using this chromatographic procedure, homo‐iso‐vaniliic acid was identified in several samples of human cerebrospinal fluid, an observation which suggests that dopamine may be partly metabolized in brain, with the production of

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01255.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—In the soluble brain proteins of various species‐man, ox, cat, rabbit, rat, mouse, hen, snake, frog and fish–there is a protein group which migrates more slowly than Moore's S‐100 protein and faster than the albumin fraction on disc electrophoresis. The protein group is absent from any organs other than brain, and has a different pattern and number of fractions in different species. Immunochemically, the protein fraction group of the mammalian brains shows some common and identical distinctive antigenic determinants compared with the brain protein of the other animals‐hen, snake, frog and fish. The protein group was designated the ‘SPR’ proteins, which were separated to ‘PII,’, ‘PIII’, ‘PIV’ and ‘Pv’ fractions. Common antigenic determinants are found in these fractions. The protein group is found in human brain in larger amounts in grey matter than in white matter and in small amounts in the cellular nuc

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01256.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY