bluuebunny/crossref_metadata_2025 huggingface dataset:
ISOLATION OF N‐ACETYLGLUTAMINE, PYROGLUTAMIC ACID AND THE BUTYL ESTER OF PYROGLUTAMIC ACID FROM HUMAN BRAIN1
Authors: Auditore J. V. , Wade L.
Published: October 2006

N‐acetyl‐l‐glutamine, pyroglutamic acid, and the butyl ester of pyroglutamic acid were isolated in pure form from an aqueous extract of human brain. These compounds were isolated by combination of paper and ion exchange chromatography. The isolated substance identified as N‐acetyl‐l‐glutamine did not react with the ninhydrin reagent but yielded glutamic acid and ammonia upon acid hydrolysis. An acetyl hydrazide was identified by paper chromatography from hydrazinolysates of the isolated substance. The glutamic acid liberated by hydrolysis had the l‐configuration. The results of elementary analysis of the isolated compound were in full accord with the analysis calculated for synthetic N‐acetyl‐l‐glutamine. A large amount of pyroglutamic acid and a substance identical with the butyl ester of pyroglutamic acid were isolated in pure form. The results of our studies suggest that pyroglutamic and the butyl ester derivative were artifacts formed during the isolation and purification procedures.
ISOLATION OF PURIFIED BASIC PROTEIN FROM HUMAN BRAIN
Authors: Banik N. L. , Davison A. N.
Published: October 2006

—A simplified method for the isolation of an encephalitogenic basic protein from myelin is described. The basic polypeptide is easily extracted from the interfacial protein which separates when chloroform‐methanol extracts of myelin are treated with a synthetic upper phase containing citrate. Evidence is presented for the purity and identity of the protein. The disc polyacrylamide gel electrophoretic pattern of this protein was consistent with a high degree of homogeneity.
PRECURSOR INCORPORATION INTO CORTICAL PROTEIN DURING FIRST EXPOSURE OF RATS TO LIGHT; CELLULAR LOCALIZATION OF EFFECTS
Authors: Rose S. P. R. , Sinha A. K. , Broomhead S.
Published: October 2006

—The rate of incorporation of [3H]lysine into acid‐insoluble material in vivo was determined in neurons and neuropil from the visual cortex of dark‐reared rats, littermates exposed to the light for varying lengths of time and normally reared controls. Following onset of light exposure, the elevation of incorporation was confined to the neuronal fraction. On continuous exposure for up to 96 h, the level of incorporation in the neuronal fraction dropped to that of the dark control value. In dark‐reared animals, the rate of incorporation in the neuronal fraction was 68 per cent of that in neuropil, in normals it was 150 per cent. On onset of exposure, the ratio in light exposed animals approached the normal level, but on prolonged continuous exposure both light exposed and normal ratios dropped to the dark control value once more. This drop did not occur if the animals were exposed to a 12 h light/dark cycle. These results are taken as suggesting that part of the protein synthesis of the visual cortex is functionally controlled, and that neuronal and neuropil fractions show a metabolic relationship which can be affected by environmental changes. The failure to show a depression of incorporation in prolonged exposure, by comparison with earlier results under somewhat different behavioural conditions, was taken as further evidence for the ‘state‐dependence’ of a number of brain biochemical parameters.
THE EFFECT OF THE CONVULSANT 3‐MERCAPTOPROPIONIC ACID ON ENZYMES OF THE γ‐AMINO‐BUTYRATE SYSTEM IN THE RAT CEREBRAL CORTEX
Authors: De Lores Arnaiz Georgina Rodríguez , De Canal Martha Alberici , Robiolo Blanca , De Pacheco Marta Mistrorigo
Published: October 2006

—The activities of GABA enzymes in rat cerebral cortex were studied after the administration of the convulsant, 3‐mercaptopropionic acid (MP). We found that MP markedly inhibited glutamate decarboxylase (EC 4.1.1.15) and activated GABA‐aminotransferase (EC 2.6.1.c). The level of GABA appeared to be decreased during convulsions but thereafter returned to normal. The study of the subcellular distribution of GABA enzymes after the administration of MP indicated that the glutamate decarboxylase present in the nerve endings was not affected, while GABA aminotransferase in the mitochondria was activated to a similar extent to that observed in the original homogenate. These results together with the recovery of glutamate decarboxylase activity in cortical homogenates by dialysis suggested a reversible type of inhibition, whereas the effect on GABA‐aminotransferase seemed to be more permanent.
STUDIES ON RAPIDLY LABELLED NUCLEAR RNA OF RAT BRAIN
Authors: Oravec M.
Published: October 2006

—Methyl albumin kieselguhr chromatography (MAK) has been employed to separate rat brain nuclear RNA, labelled in vivo with [3H]uridine, into three major fractions. The first fraction (QI RNA) is ribosomal in nature for it has a high G + C/U ratio and is methylated by [methyl‐3H] methionine. The other two fractions (Q2 RNA and TD RNA) are DNA‐like for they exhibit a low G + C/U ratio and are labelled minimally by methionine. Pure ribosomal RNA chromatographs almost entirely in the Q1 RNA fraction.

Labelling studies indicate that ribosomal RNA and DNA‐like RNA behave differently. Initially, the label in the DNA‐like RNA fractions increases rapidly and in a linear fashion for the first 30 min, but thereafter decreases rapidly and reaches a steady state level by 1 h and remains so up to at least the 2 h period. In contrast, the labelling of ribosomal RNA is much slower than that of DNA‐like RNA during the first 30 min; however, unlike DNA‐RNA, the labelling of ribosomal RNA still continues to increase linearly thereafter. Thus, during longer labelling periods, ribosomal RNA is labelled more rapidly than DNA‐like RNA. It appears that the labelling of ribosomal RNA relative to DNA‐like RNA is more rapid in liver than in brain.
SOME FACTORS AFFECTING THE UPTAKE, BINDING AND RETENTION OF [3H]CORTISOL BY THE CHICK EMBRYO RETINA AS RELATED TO ENZYME INDUCTION
Authors: Chader G. J.
Published: October 2006

—The accumulation of [3H]cortisol by the embryonic chick neural retina was studied at a time of rapid biochemical differentiation. In retinal cultures, uptake of steroid was decreased by inhibitors of energy metabolism and of sulphhydryl groups but not by inhibitors of macromolecular synthesis. The retention of steroid was inhibited by dinitrophenol and N‐ethyl maleimide (NEM) over a 3 h incubation period. This inhibition may be due, in part, to the effect of NEM on the binding of steroid to intraretinal receptor as can be demonstrated by gel filtration. Neuraminidase had no effect on [3H]cortisol uptake or retention but markedly inhibited the induction of glutamine synthetase by the steroid. Uptake and retention of steroid at 37° was greater in the retinal nuclear pellet than in the cytosol fraction; the reverse was true at 4°. After treatment with NEM, [3H]cortisol accumulation in the nuclear pellet was drastically decreased, with approximately the same level of uptake as that seen at 4°. A temperature‐dependent, sulphhydryl‐sensitive process of steroid translocation from cytoplasm to nucleus may thus be indicated.
THE SYNTHESIS OF CHOLINE AND ETHANOLAMINE PHOSPHOGLYCERIDES IN NEURONAL AND GLIAL CELLS OF RABBIT IN VITRO1
Authors: Binaglia L. , Goracci G. , Porcellati G. , Roberti R. , Woelk H.
Published: October 2006

Abstract— The de novo synthesis of phosphatidylcholine and phosphatidylethanolamine in isolated neuronal and glial cells from adult rabbit brain cortex was investigated in vitro, using labelled phosphorylcholine (phosphorylethanolamine) or cytidine‐5′‐phosphate choline (cytidine‐5′‐phosphate ethanolamine), as lipid precursors. Synthesis of phospholipid from phosphorylcholine and phosphorylethanolamine in both fractions was extremely low when compared to that derived from the corresponding cytidine nucleotides. The neuronal cell‐enriched fraction was found to possess a much higher rate of synthesis of both lipids from all precursors. Neuronal/glial ratios of about 5–9 were found for the synthesis of phosphatidylcholine and phosphatidylethanolamine from cytidine‐5′‐phosphate choline and cytidine‐5′‐phosphate ethanolamine, respectively. Several kinetic properties of the choline‐phosphotransferase (EC 2.7.8.2) and ethanolaminephosphotransferase (EC 2.7.8.1) were found to be similar both in neurons and in glia (e.g. Km of cytidine‐5′‐phosphate ethanolamine, Km of diacyl glycerol, pH optimum, need for divalent cations), but the Km value for cytidine‐5′‐phosphate choline in glial cells was much lower (2.3 × 10−4m) than in neurons (1 × 10−3m). The Kmfor cytidine‐5′‐phosphate ethanolamine in both cells was much lower than in whole brain microsomes. It is concluded that the cytidine‐dependent enzymic system for phosphatidylcholine and phosphatidylethanolamine synthesis is concentrated mostly in the neuronal cells, as compared to glia.
SOME PROPERTIES OF A MAJOR STRUCTURAL GLYCOPROTEIN OF SCIATIC NERVE
Authors: Wood J. G. , Dawson R. M. C.
Published: October 2006

The major protein of rat sciatic nerve is a glycoprotein which consists of a protein moiety attached to galactose, mannose and perhaps other sugars. On controlled tryptic digestion, it splits into a glycopeptide and a smaller fragment similar in molecular size to peripheral nerve basic proteins. Both the basic proteins of peripheral nervous system (PNS) myelin and the glycoprotein are antigenically active when administered to guinea pigs and produce sciatic nerve lesions similar to those described for experimental allergic neuritis. It is suggested from the amino acid analysis and its antigenic properties that the protein moiety of the glycoprotein may contain a sequence which is similar to the basic proteins of PNS myelin.
FREE AMINO ACIDS IN DEVELOPING RAT RETINA
Authors: Macaione S. , Ruggeri P. , Luca F. De , Tucci G.
Published: October 2006

—During postnatal growth the free amino acids pattern of rat retina differs at various developmental stages. The adult level for individual amino acids is reached on the 30th day of maturation. During differentiation the taurine, glutamic acid, GABA, glutamine, aspartic acid, glycine arginine, methionine and histidine levels increase while proline. alanine, ornithine and tyrosine decrease.
PROPERTIES OF ACETYLCHOLINESTERASE FROM RAT BRAIN
Authors: Wenthold R. J. , Mahler H. R. , Moore W. J.
Published: October 2006

—Acetylcholinesterase (EC 3.1.1.7) from cerebral cortex of mature rats was purified by means of affinity chromatography, to a specific activity of 4.5 mmol acetylthiocholine hydrolysed × min−1× mg−1 protein. The enzyme is a glycoprotein and contains a single subunit with a mol. wt of about 80,000. Electrofocusing either a pure or a crude preparation of the enzyme produces six enzymatically active bands with a range of isoelectric points from 5.04 to 5.54. Gel filtration yields oligomers with molecular weights of about 150,000, 320,000, 500,000 and 650,000, with 60 per cent of the activity in the 150,000 fraction. The gel fractions with molecular weights 150,000 and 320,000 produce the same isoelectric patterns. Different subcellular fractions of the cortex show different characteristic isoenzyme patterns.
EFFECTS OF MAPLE SYRUP URINE DISEASE METABOLITES ON MOUSE l‐FIBROBLASTS IN VITRO: A FINE STRUCTURAL AND BIOCHEMICAL STUDY
Authors: Bissell M. G. , Bensch K. G. , Herman M. M.
Published: October 2006

—The branched‐chain amino and ketoacids [i.e. l‐leucine, l‐isoleucine, l‐valine, alpha‐ketoisocaproic acid (AKICA), alpha‐keto‐beta‐methylvaleric acid (AKBMVA) and alpha‐ketoisovaleric acid (AKIVA)] were administered to mouse strain l fibroblasts in tissue culture in an attempt to study the effects of increased levels of the compounds in an in vitro system. All of these compounds are found to be elevated in the blood of patients with Maple Syrup Urine Disease (MSUD).

With AKICA, l‐leucine, AKIVA and AKBMVA, there was a decreased growth rate at concentrations of 10 to 30 times the levels found in Maple Syrup Urine Disease. Combined administration of the above six compounds at the maximum blood levels noted in MSUD produced a significantly decreased growth rate. Electron microscopic studies revealed numerous annulate lamellae in cells treated with AKICA and in those treated with a combination of all six MSUD compounds. AKICA‐treated cells contained elevated concentrations per cell of free fatty acids, triglycerides, sterols and some classes of phospholipids. Isotope labelling experiments were performed using [U‐14C] AKICA and [3H]isoleucine, which were added to l‐cell suspension cultures containing various levels of unlabelled AKICA. Labelled AKICA and isoleucine were both taken up by the cells. The net uptake of isoleucine was inhibited by AKICA in concentrations found in MSUD. Folch‐Lees extraction of cells treated with labelled AKICA revealed increased 14C counts only in the lower lipid phase.

The growth inhibition and annulate lamellae observed with AKICA treatment may be due to an arrest of the cells in phase G1 of the cell growth cycle, possibly due to decreased isoleucine uptake. It is proposed that a similarly‐mediated arrest in the proliferation of oligodendroglial cells during the critical period of myelination gliosis might account for the myelination abnormalities reported in MSUD.
INCORPORATION OF d‐[3H]GLUCOSAMINE INTO THE SIALOGLYCOPROTEIN GP‐350 OF ADULT RAT BRAIN
Authors: Van Nieuw Amerongen A. , Ferwerda W. , Roukema P. A.
Published: October 2006

—The incorporation of d‐[3H]glucosamine into the nervous specific sialoglycoprotein GP‐350 has been studied in adult rat brain. Both the 100,000 g supernatant fluid and the 12,500 g pellet were used for the investigation, since GP‐350 could only be detected in the soluble cell fraction (Van Nieuw Amerongenet al., 1972) and in the synaptosomal membranes, sedimenting in the crude mitochondrial fraction (Van Nieuw Amerongen & Roukema, 1973, 1974). GP‐350 was separated from the other proteins by polyacrylamide gel electrophoresis at pH 7.5 and the incorporation of radioactivity into GP‐350 was measured at different time intervals, ranging from 1 to 96 h after the administration of the radioisotope. The maximal incorporation of radioactivity into the soluble GP‐350 was obtained after about 2 h and into the membrane‐bound GP‐350 after about 3 h. After 2 h there is a very rapid decrease of the radioactivity of GP‐350 from the soluble cell fraction (up to 70 per cent within 2 h). Thereafter the disappearance is more gradual and of the same order as that found for the membrane‐bound fraction of GP‐350. The half‐life of the soluble GP‐350 was estimated to be 19 h and for the membrane‐bound GP‐350 a value of 18 h was calculated. Compared to the total pool of brain (glyco) proteins and specific nervous (glyco) proteins GP‐350 has a very rapid turnover. The rapid initial decrease of the radioactivity from the soluble GP‐350 may be interpreted in terms of a rapid transport of the newly‐synthesized GP‐350 from the cytoplasma of the perikaryon to the membranes of the synaptic region by an axoplasmic flow.
CHANGES IN VESICULAR DOPAMINE‐β‐HYDROXYLASE RESULTING FROM TRANSMITTER RELEASE
Authors: Fillenz Marianne , West D. P.
Published: October 2006

—Exposure of rats to 3°C for up to 30 min leads to a decrease of 30 per cent in the dopamine‐β‐hydroxylase activity of the vesicular pellet of the heart; this is greater than can be accounted for by loss of soluble DBH from the two populations of noradrenaline storage vesicles known to be present in the heart. Cold exposure in the presence of α‐methyltyrosine causes a much smaller reduction in dopamine‐β‐hydroxylase activity; this suggests that there is a decrease in transmitter release when synthesis is inhibited. The noradrenaline concentration of the vesicular pellet rises briefly during cold exposure and is then maintained at control levels; the early rise is absent in the presence of α‐methyltyrosine. The use of the noradrenaline : dopamine‐β‐hydroxylase ratio as an index of saturation of vesicular storage capacity suggests that during cold exposure an increased synthesis rate leads to increased filling of vesicles.
REACTIONS OF FREE AND tRNA BOUND GLUTAMATE AND GLUTAMINE
Authors: Murthy M. R. V. , Roux Huguette
Published: October 2006

—[14C]‐Glutamate and [14C]‐glutamine were incorporated into calf brain tRNA in the presence of homologous aminoacyl‐tRNA synthetases. When the tRNAs were then deaminoacylated and chromatographed, a number of radioactive products were found in addition to the original amino acids. One of the products of glutamate transformation was identified to be glutamine. Formation of the radioactive products of glutamate in the presence and absence of tRNA indicated that glutamine was produced from glutamate at the level of the free amino acid followed by the incorporation of both substances into tRNA. Examination of the products of deaminoacylation of glutaminyl‐tRNA showed that glutamine underwent structural alterations at the level of the aminoacyl‐tRNAs to give rise to a cyclic derivative of glutarimide. This reaction was specific for glutamine, and constituted approximately 15 per cent of the total radioactivity in the deaminoacylation products of glutaminyl‐tRNA.
ON THE DEVELOPMENT OF SYMPATHETIC NERVE TRUNK VESICLES DURING AXONAL TRANSPORT: DENSITY GRADIENT ANALYSIS OF DOPAMINE β‐HYDROXYLASE IN BOVINE SPLENIC NERVE
Authors: Lagercrantz H. , Kirksey D. F. , Klein R. L.
Published: October 2006

—Dopamine β‐hydroxylase was used as a marker enzyme for sympathetic nerve vesicles which were studied by density gradient technique in bovine splenic nerves. The enzyme analyses were complicated by the occurrence of inhibitors which had to be carefully neutralized with copper. The inhibitor was mainly found in the soluble fraction and no evidence for the occurrence of endogenous inhibitors in the nerve vesicles was obtained.

A great variation in density of the dopamine β‐hydroxylase containing particles was observed. This was probably mainly due to the variation in vesicle maturation since dopamine β‐hydroxylase was distributed more towards the lighter gradient fractions in the proximal nerve segment preparations compared with intrasplenic nerve segment preparations. Noradrenaline/protein and noradrenaline/dopaminc β‐hydroxylase ratios were found to be increased about 1·7‐fold in the vesicle fraction isolated from the proximal nerve segments to those from the intrasplenic segments. A further increase of the noradrenaline/dopamine β‐hydroxylase ratio was observed in a fraction with the same density isolated from the spleen. On the basis of these findings the noradrenaline/protein ratio was calculated to be about 500‐600 nmol/mg in the nerve terminal vesicles.
FORSSMAN HAPTEN N‐ACETYL‐α‐D‐GALACTOSAMINIDASE IN RAT BRAIN AND KIDNEY1
Authors: Israel M. , Bach G. , Miyatake T. , Naiki M. , Suzuki K.
Published: October 2006

—Forssman hapten (N‐acetyl‐α‐galactosaminosyl‐N‐acetyl‐β‐galactosaminosyl‐α‐galactosyl‐β‐galactosyl‐glucosylceramide), prepared from sheep erythrocytes was specifically labelled with tritium at the terminal N‐acetyl‐α‐galactosamine moiety by the galactose oxidase‐sodium [3H]borohydride method. Activities to cleave the terminal N‐acetyl‐α‐galactosamine from Forssman hapten were detected in the high‐speed supernatant of the frozen‐thawed and sonicated crude mitochondrial fraction from adult rat brain and kidney. The optimal pH of the reaction was approximately 4·4. The reaction was linear for at least 1 h for the kidney enzyme and up to 3 h for the brain enzyme. Taurocholate was required for the activity. The optimal concentration was 1·5‐2 mg/ml. Several other detergents and bile salts tested could not replace taurocholate. The apparent Km of the brain and kidney enzymes were 1·0×10−4M and 3·5×10−4m, respectively. During development, Forssman hapten‐cleaving activities of both brain and kidney gradually declined in specific activity as the animal matured. These changes were similar to those of nonspecific p‐nitrophenyl N‐acetyl‐α‐galactosaminidase. Several rat organs examined all showed detectable activities to cleave Forssman hapten.
FATE OF l‐GLUTAMATE IN THE BRAIN
Authors: Benjamin A. M. , Quastel J. H.
Published: October 2006

Abstract— It is shown, using aminooxyacetate as metabolic inhibitor, that the process of oxidation of endogenous glutamate in incubated rat brain cortex slices follows a different course from that of exogenous l‐glutamate. Whereas endogenous glutamate is largely oxidized by an initial reaction with glutamate dehydrogenase with release of ammonia, exogenous l‐glutamate undergoes initial transamination to aspartate and α‐oxoglutarate before oxidation occurs. In the presence of 2·5 mm l‐glutamate, it is found that, of the total exogenous glutamate utilized, 49 per cent is converted to aspartate, 37 per cent is converted to glutamine and the rest is f uily oxidized through glutamate dehydrogenase. It is suggested that endogenous glutamate is normally oxidized in the neurons, and that glutamate released from neurons during excitation, and acting therefore as exogenous glutamate, is taken up by the glia where, besides conversion to glutamine, it largely undergoes initial transamination before oxidation takes place.
THE EFFECT OF ELEVATED AMINO ACIDS ON AMINOTRANSFERASE LEVELS IN BRAIN AND LIVER OF THE MOUSE
Authors: Benuck M. , Lajtha A.
Published: October 2006

Abstract— Adult mice were fed standard diets that were enriched with selected amino acids, i.e. 3% methionine, 6% valine, or 8% lysine. These diets caused the following changes in the amino acid pool of the brain measured at 7 and 21 days. The high methionine diet resulted in 50‐fold higher levels of methionine and cysteine and somewhat lower levels of serine and glutamine. The valine and lysine‐enriched diets also caused 2‐ to 4‐fold increases in valine and lysine contents of brain, respectively. In spite of the large changes in amino acid levels, however, there were essentially no changes in aspartate: α‐ketoglutarate, alanine: α‐ketoglutarate, ornithine: α‐ketoglutarate, methionine: α‐ketoglutarate, and the branched chain aminotransferase activities of brain 3, 10, and 21 days after the onset of the dietary regimen. In contrast, these diets produced significant changes in some of these enzyme activities in liver. Changes in liver included a 2‐fold increase in ornithine and alanine aminotransferase activities with the methionine‐enriched diet. Liver ornithine aminotransferase activity also increased slightly in animals fed the valine‐enriched or lysine‐enriched diet.
NEONATAL UNDERNUTRITION AND RNA SYNTHESIS IN DEVELOPING RAT BRAIN1
Authors: De Guglielmone AliciaE. R. , Soto Ana M. , Duvilanski Beatriz H.
Published: October 2006

—Underfeeding of newborn rats results in a decreased body and brain weight at 10, 20 and 30 days of age. The DNA and RNA content of the brain in these animals are similar to those of normal controls. The in vivo and in vitro synthesis of RNA in brain is significantly decreased in undernourished rats at 10 days of age when compared with controls. The metabolic transformation of 3H‐orotic acid to nucleotides is also diminished. A short period of food rehabilitation produces ‐an improvement in the above mentioned alterations. However, a reduced incorporation of label into microsomal RNA persists even in the last condition. The results suggest that malnutrition, during the first days of life, alters the metabolism of cerebral RNA.
THE METABOLISM OF [14C]GLUCOSE BY THE BRAINS OF SUCKLING RATS INTOXICATED WITH INORGANIC LEAD
Authors: Patel A. J. , Michaelson I. A. , Cremer J. E. , Balázs R.
Published: October 2006

—The development with age of the pattern of distribution of glucose carbon characteristic of the adult brain was studied in 7‐, 13‐, 19‐ and 24‐day‐old rats suckling from mothers maintained on a diet containing 4·5% lead acetate or on a normal diet. In normal rats the rapid and extensive conversion of glucose carbon into amino acids associated with the tricarboxylic acid cycle has been shown to develop in the cerebellum and the cerebral cortex during the same period as previously observed for the whole forebrain. A significant retardation was observed in both brain parts of rats suckling from mothers ingesting lead. In comparison with glutamate, aspartate and γ‐aminobutyrate, the labelling of glutamine was particularly low. The concentration of glutamine was not affected in the forebrain, but it was elevated in the cerebellum. The age‐dependent rise in the amounts of glutamate and aspartate was also retarded, but it would appear that the contribution of this effect to the depressed labelling of amino acids was small. There was no evidence of impaired entry of glucose into the brain from the blood. Although in comparison with undernourished animals, the growth retardation of the lead‐treated rats is similar, several of the effects observed on the developing brain seem to be distinct.
ENZYMATIC ACYLATION OF 1‐ALKYL‐, 1‐ALKENYL‐AND 1‐ACYL GLYCERO‐3‐PHOSPHORYLETHANOLAMINE IN DEVELOPING RAT BRAIN
Authors: Natarajan V. , Sastry P. S.
Published: October 2006

Abstract— Rat brain particulate fractions were shown to acylate [32P]1‐alkyl‐sn‐glycero‐3‐phosphorylethanolamine (GPE). While the main product is 1‐alkyl‐2‐acyl GPE, about 12 per cent of the radioactivity was also found in 1‐alkenyl‐2‐acyl GPE. The acyl transferase activity was completely dependent on added ATP and CoA and it was localized mainly in the microsomal fraction. A comparative study of acyl transferase activities to 1‐alkyl‐, 1‐alkenyl‐, and 1‐acyl GPE by crude mitochondrial fraction and microsomes of 10, 16 and 22‐day‐old rat brains showed a progressive increase in activity with development. In the 22‐day‐old rat brain the order of activity towards the three substrates is as follows: 1‐acyl GPE ± 1‐alkenyl GPE ± 1‐alkyl GPE with a crude mitochondrial fraction and 1‐acyl GPE ± 1‐alkyl GPE ± 1‐alkenyl GPE with microsomes.
DECARBOXYLATION OF EXOGENOUS l‐5‐HYDROXYTRYPTOPHAN AFTER DESTRUCTION OF THE CEREBRAL RAPHE SYSTEM
Authors: Korf J. , Venema K. , Postema F.
Published: October 2006

Abstract— l‐5‐Hydroxytryptophan (l‐5‐HTP) was administered intravenously to rats (12 mg/kg) after inhibition of the peripheral aromatic l‐amino acid decarboxylase with l‐α‐hydrazino‐α‐methyl dopa (MK 486). The accumulation of 5‐hydroxytryptamine (5‐HT) and 5‐hydroxyindoleacetic acid in the cerebral cortex was measured 1, 2 and 4 h after injection of 5‐HTP with automated assay techniques. Besides controls two groups of rats were studied: rats after inhibition of tryptophan‐5‐hydroxylase with p‐chlorophenylalanine (pcpa) and subjects with a chronic lesion in the area of the raphe nucleus. The net accumulation of both measured 5‐hydroxyindoles was diminished in rat cerebral cortex after degeneration of 5‐HT containing nerve endings, compared with control animals and pcpa‐treated rats. These results indicate that the formation of 5‐HT in the cerebral cortex from exogenous l‐5‐HTP, after inhibition of the peripheral aromatic amino acid decarboxylase, occurs predominantly in 5‐HT containing nerve endings possibly by a specific 5‐HTP‐decarboxylating enzyme.
SQUALENE‐2(3)‐EPOXIDE‐LANOSTEROL CYCLASE IN DEVELOPING RAT BRAIN1
Authors: Dennick R. G. , Dean P. D. G.
Published: October 2006

Abstract— Squalene‐2(3)‐epoxide‐lanosterol cyclase activity has been studied in cell‐free extracts of developing rat brain. The enzyme is microsomal and is not stimulated by the addition of 100,000 g supernatant fluid. It is activated by deoxycholate in a manner similar to that of the liver cyclase. It is not inhibited by nicotinamide over a wide range of concentrations but is strongly inhibited by the hypocholesteraemic agent N‐dodecylimidazole. Cyclase activity increases from low levels at 5 days of age to maximum activity at 13 days and thereafter slowly declines. The increase in activity is independent of increases in total brain protein and has been analysed by the method of ‘chemical allometry’. Using this technique it can be seen that prior to 13 days the proportion of brain protein allotted to cyclase is increasing whereas after this time it decreases.
LIPID COMPOSITION IN GRAY AND WHITE MATTER OF THE BRAIN IN MENKES' DISEASE
Authors: Lou H. C. , Hølmer Gunhild K. , Reske‐Nielsen Edith , Vagn‐Hansen P.
Published: October 2006

Abstract— Lipid composition has been determined in brain frontal lobe gray and white matter from a 5‐month‐old patient who died from Menkes' disease, and from a normal control patient of the same age.

Total cholesterol and the amount of cholesterol esters were significantly increased in the case of Menkes' disease, whereas the values for free cholesterol were nearly unchanged.

In white matter a decrease in total galactolipids was observed in the pathological brain.

The values for total phospholipids were unchanged for the tissues, but the ratio between phosphatidylcholines and phosphatidylethanolamines (including ethanolamineplasmalogens) in white matter from the patient seemed increased. The fatty acid pattern of phosphatidylethanolamines (including ethanolamineplasmalogens), phosphatidylcholines and sphingomyelin were similar to those of the normal control. Phosphatidylethanolamines from pathological tissues contained 25–30 per cent polyunsaturated fatty acids with four, five or six double bonds.
INCORPORATION OF AMINO ACIDS INTO PROTEINS IN NEURONAL AND NEUROPIL FRACTIONS OF RAT CEREBRAL CORTEX: PRESENCE OF A RAPIDLY LABELLING NEURONAL FRACTION
Authors: Rose S. P. R. , Sinha A. K.
Published: October 2006

Abstract— The time course of incorporation of intraperitoneally injected [3H]lysine and [14C]phenylalanine into neuronal and neuropil proteins has been followed for up to 8 days. At short times after injection (<2 h) the specific activity of the neuronal fraction was higher than that of the neuropil. At longer time intervals, although the total brain specific activity continued to rise, neuronal perikaryal specific activity fell below that of neuropil. Thus the neuronal/neuropil incorporation ratio with [3H]lysine as substrate was 1·5 at 1 h, but by 4 h had fallen to 0·4, a ratio which was maintained for up to 8 days. A similar reversal occurred with phenylalanine as substrate. These changes were interpreted as evidence for the presence of a rapidly‐labelling protein fraction in the neurons which is subsequently transported out. Subcellular fractionation showed that over the 4 h period the rapidly labelling fraction was not transported to the synaptosomes. Incubation of prelabelled cortex slices followed by cell fractionation showed that a differential transport of protein of higher than average specific activity from both neurons and neuropil fractions occurred; there is a tendency for preformed highly labelled protein to accumulate during the in vitro incubation in Fraction D, a pellet enriched in red cells, some large neuronal perikarya and cell nuclei. When cell fractions were prepared after in vitro incubation, the distribution of the material down the gradient differed from that when fresh tissue was fractionated, as demonstrated by microscopic examination and the distribution of β‐galactosidase, a neuronal marker. Double‐label experiments showed that this redistribution could not account for the preferential loss and accumulation of prelabelled protein. It was noted that in vivo incorporation into the rapidly labelling neuronal protein is suppressed under certain changed environmental conditions, such as dark rearing. This is interpreted as lending support to the concept of the state‐dependence of neuronal and neuropil protein synthesis and their inter‐relations.
THE FATTY ACID COMPOSITION OF SPHINGOLIPIDS FROM BOVINE CNS AXONS AND MYELIN1
Authors: DeVries G. H. , Norton W. T.
Published: October 2006

Abstract— Cerebrosides, sulphatides and sphingomyelin were isolated from bovine CNS myelin and from myelin‐free axons derived from myelinated axons. The fatty acid composition of each sphingolipid was determined by gas‐liquid chromatography of the fatty acid methyl esters. In each case the fatty acids of the axonal sphingolipids were of shorter average chain length than those from the corresponding myelin lipids. These differences, however, were small and the fatty acids of the axonal cerebrosides and sulphatides were similar in average chain length to those reported previously for bovine myelin. The principal unsubstituted acid of both cerebroside and sulphatide from axons was 24: 1, with the total long chain acids (> C18) amounting to 80 and 85 per cent, respectively. The corresponding figures for myelin galactolipids were 94 and 95 per cent long chain acids. The principal α‐hydroxy acid of both axonal galactolipids was 24 h:0, with cerebroside having 80 per cent and sulphatide 92 per cent long chain acids, compared to the figures of 87 and 97 per cent for the corresponding myelin lipids. In axonal sphingomyelin the major acid was 18:0 (compared to 24:1 in myelin) and the long chain acids were 61 per cent of the total vs 76 per cent of the total for myelin sphingomyelin. The non‐identity of axonal and myelin sphingolipid fatty acids substantiates the belief that they are intrinsic axonal constituents. These findings do not rule out the possibility of a close metabolic relationship between the sphingolipids of the axon and its myelin sheath.
RESPIRATION IN IMMATURE RAT BRAIN MITOCHONDRIA
Authors: Holtzman D. , Moore C. L.
Published: October 2006

—Respiration was studied polarographically in mitochondria isolated from immature rat cerebral hemispheres. Respiratory rates are compared as a function of age, substrate, and the requirement for a phosphate acceptor.

1. All respiratory rates are low in the first week of life. These rates increase during the first month and then decline to about the newborn rate by 5 weeks of age.

2. With the NAD‐linked substrate pair, glutamate and malate, the changes with age are significant only for the rate of ADP‐dependent respiration. With succinate as substrate, significant age‐dependent changes in respiration occur only in ADP‐independent respiration.

3. In mitochondria from animals less than five weeks of age, the ADP‐dependent respiratory rate is significantly greater with the NAD‐linked substrate pair than with succinate. In mitochondria from older animals, both ADP‐dependent and ADP‐independent rates are greater with succinate.
THE BIOSYNTHESIS OF 3‐METHOXY‐4‐HYDROXYPHENYLGLYCOL SULPHATE BY LIVER AND BRAIN
Authors: Wong K. P.
Published: October 2006

—3‐Methoxy‐4‐hydroxyphenylglycol (MHPG) formed a sulphate conjugate when incubated with ATP, Mg2+ ions, Na235SO4 and the high‐speed supernatant preparations of rabbit or rat brain. The same reactions could be catalysed by similar enzyme preparations from liver. The sulphated product was separated and identified by paper chromatography. On acid hydrolysis, it released both Na235SO4 and the free glycol. The measurement of this labelled sulphate was used as a specific assay procedure for determining the overall sulphoconjugatory process. The pH optimum of the reaction is 7.8. For rabbit brain, the Km for Na2SO4 determined for the activating system is 3.6 × 10−4m, and that for MHPG for the sulphotransferase reaction is 1.05 × 10−4m. The specific enzyme activity, expressed as nmol 35SO4 incorporated/h/mg protein for a 30‐min assay is as follows: rat brain, 2.8; rabbit brain, 1.6; rat liver, 33.4and rabbit liver, 15.0. Dithiothreitol at 3 mm concentration had no significant effect on the sulphation of MHPG in all these preparations.
REGIONAL AND SEXUAL DISTRIBUTION PATTERNS OF CHROMATIN PROTEINS AND OF SOLUBLE CYTOPLASMIC PROTEINS IN THE RAT BRAIN1
Authors: Yu J. Y.‐L.
Published: October 2006

Abstract— Electrophoretic patterns of forebrain and hindbrain proteins were compared in normal adult rats of both sexes, as well as in adult female rats following neonatal androgenization. There were significant differences between the forebrains and hindbrains in the relative densities of several chromatin proteins and soluble cytoplasmic protein bands. Minor qualitative differences between forebrains and hindbrains were observed in patterns of chromatin proteins. No qualitative sex difference was detectable in the patterns of chromatin‐derived proteins or in soluble cytoplasmic proteins. The relative densities of the brain protein bands were very similar for both sexes, indicating quantitative equivalence as well. The brain protein electrophoretic patterns of adult females following neonatal androgenization were identical qualitatively to those of normal females in respect to both chromatin and cytoplasmic proteins.
ATPASE AND PHOSPHATIDYLINOSITOL KINASE ACTIVITIES OF ADRENAL CHROMAFFIN VESICLES
Authors: Muller T. W. , Kirshner N.
Published: October 2006

Abstract— The hypothesis that the ATPase and phosphatidyhnositol (PI) kinase activities of chromaffin vesicle membranes are catalysed by same enzyme was investigated. The two activities exhibited entirely different responses to variations in Mg2+ or Mn2+ concentrations. In the presence of 1 mM ATP, maximal ATPase activity occurred with 1 mM Mg2+ while maximal PI kinase activity required 100 mM Mg2+ Similar differences were observed with Mn2+ with the exception that maximal ATPase activity occurred with 0.5 mM Mn2+ and maximal PI kinase activity occurred with 5 mM Mn2+ Mn2+ was more effective than Mg2+ in stimulating PI kinase activity at low concentrations, but at optimal concentrations of each, the maximal activity obtained with Mg2+ was 5‐fold greater than the maximal activity obtained with Mn2+ The heat stabilities of the two enzymes are vastly different. At 50°C the ATPase activity of the intact membranes was stable for up to 20 min while the tl/2 of PI kinase was less than 2 min. After solubilization in Lubrol PX or at higher temperatures both enzymes were less heat stable, but PI kinase was still inactivated at a much greater rate than the ATPase. The evidence suggests that the ATPase and the PI kinase are different proteins.

The major phosphorylated product was diphosphatidylinositol and once formed, it was stable. Phosphorylation of membrane protein accounted for less than 10% of the total 32P‐incorporated into chromaffin vesicles. SDS gel electrophoresis of the solubilized membranes showed the presence of at least 2 major phosphorylated high molecular weight components.
A METHOD FOR THE ESTIMATION OF γ‐AMINOBUTYRIC ACID USING GAS‐LIQUID CHROMATOGRAPHY AND ELECTRON CAPTURE DETECTION
Authors: Pearson J. D. M. , Sharman D. F.
Published: October 2006

Abstract— A method for the estimation of γ‐aminobutyric acid (GABA) in brain tissue using gas‐liquid chromatography is described. The method is based on the formation of an electron‐capturing derivative of GABA by treatment with 1,1,1,3,3,3‐hexafluoroisopropanol and trifluoroacetic anhydride under mild conditions. The method is comparatively simple and shows high specificity and sensitivity.
NEURONAL AND GLIAL SYSTEMS FOR γ‐AMINOBUTYRIC ACID METABOLISM
Authors: Sellström Å. , Sjöberg L.‐B. , Hamberger A.
Published: October 2006

—Bulk prepared neuronal perikarya, nerve endings and glial cells have been used to study amino acid concentrations and GABA metabolism in vitro. All amino acids were more concentrated in synaptosomes and glial cells than in neuronal perikarya. Cell specificity was found with respect to the relative distribution of some amino acids. Glutamate decarboxylase activity was considerably higher in synaptosomes than in glial cells. The inhibitory effect of amino‐oxyacetic acid on glutamate decarboxylase activity differed between synaptosomes and glial cells. γ‐Aminobutyric acid‐α‐ketoglutarate transaminase had the highest activity in the glial cell fraction; the inhibition of amino‐oxyacetic acid differed between glial and neuronal material. The metabolism of exogenous GABA just accumulated by a cell showed similar time characteristics in neuronal and glial material.
MEMBRANE‐BOUND NEURAMINIDASE IN THE BRAIN OF DIFFERENT ANIMALS: BEHAVIOUR OF THE ENZYME ON ENDOGENOUS SIALO DERIVATIVES AND RATIONALE FOR ITS ASSAY
Authors: Tettamanti G. , Preti A. , Lombardo A. , Suman T. , Zambotti V.
Published: October 2006

—The activity of brain membrane‐bound neuraminidase on endogenous and exogenous substrates was comparatively studied in various animals (rat, chicken, rabbit, pig, calf and human). The maximum rate of hydrolysis of endogenous substrates by membrane‐bound neuraminidase (using a crude preparation of the enzyme) was different in the various animals (from 0·05 to 0·73 units, referred to 1 mg protein) and was obtained under similar but not identical optimum conditions (pH from 4·1 to 5·1; requirement or not of Triton X‐100). The maximum degree of hydrolysis of endogenous substates was also different (from 15 to 27 nmol released NeuNAc/mg protein) and was obtained within different incubation periods (from 2 to 18 h). It corresponded (in rabbit, calf, human brain only), or not, to the actual exhaustion of the endogenous substrates.

The endogenous substrates were recognized as both gangliosides and sialoglycoproteins. The extent of hydrolysis of sialoglycoproteins varied from 1·5% in rabbit to 15·6% in chicken brain; the hydrolysis of gangliosides (ranging from 14·1% in pig to 53·7% in rabbit brain) reached only in some animals (rabbit, calf, human) the complete transformation of major oligosialogangliosides into the neuraminidase resistant monosialoganglioside GMI. Upon addition of exogenous substrates (sialyl‐lactose, ganglioside GD1a, brain sialopeptides, ovine submaxillary mucin) the actual rate of liberation of total NeuNAc (from both endogenous and exogenous substrates) considerably exceeded, although at a different extent (depending on the animal and on the added substrate used) the rate of hydrolysis of sole endogenous substrates. The possibility of an accurate assay of brain membrane‐bound neuraminidase in a crude enzyme preparation is evaluated and guidelines for the assay procedure suggested.
THE EFFECT OF ASPARTATE ON CITRATE METABOLISM IN THE CYTOSOLIC FRACTION OF BRAIN UNDER CONDITIONS OF NORMOXIA, HYPOXIA AND ANAESTHESIA
Authors: Rafalowska Urszula , Erecińska Maria , Chance B.
Published: October 2006

—The utilization of citrate by the cytoplasmic fraction of rat brain is inhibited in hypoxia and remains unaltered in anaesthesia. The addition of exogenous aspartate to the cytosolic fraction isolated from brains of hypoxic animals increases the rate of citrate removal. The level of cytosolic aspartate gradually decreases when the exposure period to low oxygen tension is increased and reaches a minimum after 30 min.

The levels of mitochondrial aspartate and of cytoplasmic carbamyl aspartate remain constant. The low level of cytosolic aspartate is accompanied by an increase in the concentration of cytosolic urea and increase in the aspartate level in blood serum. It is suggested that the oxidation of citrate by the cytoplasmic fraction of brain is inhibited in hypoxia owing to the decrease in endogenous aspartate. The decrease in the level of cytoplasmic aspartate is caused by the diversion of this substrate toward urea synthesis and by the increased leakage across the cell/blood barrier to the blood stream. Anaesthesia prevents the changes induced by hypoxia.
CHARACTERIZATION OF POLY(A) SEQUENCES IN BRAIN RNA
Authors: Mahony J. B. , Brown I. R.
Published: October 2006

—Nuclear and polysomal brain RNA from the rabbit bind to Millipore filters and oligo(dT)‐cellulose suggesting the presence of poly(A) sequences. The residual polynucleotide produced after RNase digestion of 32P pulse‐labelled brain RNA is 95% adenylic acid and 200‐250 nucleotides in length. After longer isotope pulses the polysomal poly(A) sequence appears heterodisperse in size and shorter than the nuclear poly (A). Poly(A) sequences of brain RNA are located at the 3′‐OH termini as determined by the periodate‐[3H]NaBH4 labelling technique. Cordycepin interferes with the processing of brain mRNA as it inhibits in vivo poly(A) synthesis by about 80% and decreases the appearance of rapidly labelled RNA in polysomes by about 45%. A small poly(A) molecule 10‐30 nucleotides in length is present in rapidly labelled RNA. It appears to be less sensitive to cordycepin than the larger poly(A) and is not found in polysomal RNA.
ACTIONS OF 6‐HYDROXYDOPAMINE QUINONES ON CATECHOLAMINE NEURONS1
Authors: Jonsson G. , Sachs Charlotte
Published: October 2006

—The effect of the para‐(PQ) and the ortho‐(OQ) quinones of 6‐hydroxydopamine (6‐OH‐DA) on transmitter uptake‐storage mechanisms of catecholamine neurons in mouse and rat has been investigated. After the administration of PQ and OQ there was a dose‐dependent and long‐lasting disappearance of noradrenaline (NA) nerve terminals as demonstrated by fluorescence histochemistry and a reduction of the in vitro uptake of [3H]NA in mouse atrium and iris. These effects could be completely counteracted by blockade of the ‘membrane pump’ transport mechanism with desipramine, while monoamine oxidase inhibition, by nialamide and administration of ascorbic acid potentiated the effects produced by the two quinones. The results obtained after PQ and OQ were largely identical with those seen after administration of 6‐OH‐DA, well‐known for its neurotoxic action on catecholamine neurons. It is therefore concluded that PQ and OQ are able to produce an acute and selective degeneration of NA nerve terminals similar to that of 6‐OH‐DA. The results obtained after intraventricular injection of the quinones into rat brain were also in agreement with this view. Neonatal administration of PQ or OQ to mice caused a permanent and marked decrease in [3H]NA uptake in the cerebral cortex and the spinal cord, whereas the uptake was markedly increased in the pons‐medulla, similar to that seen after 6‐OH‐DA. The PQ and the OQ were equally potent in most experiments although clearly less potent than 6‐OH‐DA itself. The quinones were also found to be equally or slightly less potent than 6‐OH‐DA in affecting [3H]NA uptake and retention in vitro in atrium and cerebral cortex from untreated mice. It may be concluded that PQ and OQ exert their neurotoxic action on NA neurons after transition to 6‐OH‐DA, after a rapid extraneuronal equilibration. 6‐OH‐DA thus formed can thereafter be taken up and accumulated intraneuronally by use of the ‘membrane pump’ and the specific degenerative action is elicited. The lower neurotoxic potency of the quinones may be attributed to their known ability to undergo covalent binding with proteins and/or formation of 5,6‐dihydroxyindole.