bluuebunny/crossref_metadata_2025_split huggingface dataset:
CALCIUM‐DEPENDENT BINDING OF BRAIN GLUTAMATE DECARBOXYLASE TO PHOSPHOLIPID VESICLES
Authors: Covarrubias Manuel , Tapia Ricardo 
Published: October 2006

AbstractThe binding of glutamate decarboxylase (GAD), to phospholipid vesicles (liposomes) in the absence and in the presence of several Ca2+ and Mg2+ concentrations was studied. Phosphatidylcho‐line‐phosphatidylserine (4:1) liposomes are capable of binding GAD in a Ca2+‐dependent manner. The per cent of GAD bound increased from 5 to 65°., in a sigmoid shape with Ca2+ concentrations in the 0.2‐4 mm range. Mg2+ also induces GAD binding but is less effective than Ca2+ The Ca2+ ‐dependent binding of GAD is not the result of unspecific association of protein, since Ca2+ did not promote any binding of choline acetyltransferase or lactate dehydrogenase. Furthermore, the relative specific activity (oo enzyme activity/% protein) of GAD associated to liposomes increases 4‐fold from 0 to 2 mm Ca2+. The per cent of GAD bound attains a plateau at a ratio phospholipid/protein of about 1.5. and decreases when the pH increases from 6.5 or 6.8 to 7 or 7.25. Na+ or K+ at a 100mm concentration also induce binding of GAD to liposomes. Phosphatidylcholine liposomes (without phosphatidylserine) practically did not bind GAD at any Ca2+ concentration. The Ca2+‐dependent association of GAD to phosphatidylcholine‐phosphatidylserine liposomes is very similar to that previously reported using brain membranes, and it correlates also well with the reported Ca2+‐dependent aggregation of phosphatidylserine molecules in phospholipid membranes of similar composition. It is concluded that phosphatidylserine is probably involved in the Ca2+‐dependent binding of GAD to brain membranes. Phospholipid vesicles seem to be a useful experimental model for studying the mechanisms of this GAD association to membranes and the possible physiological implications of the GAD‐Ca2+‐membrane interaction regarding the release of newly synthesized GABA from nerve endings.
RELEASE OF ATP FROM A SYNAPTOSOMAL PREPARATION BY ELEVATED EXTRACELLULAR K+ AND BY VERATRIDINE
Authors: White T. D. 
Published: October 2006

Abstract—A technique was developed which permitted the release of ATP from synaptosomes by elevated extracellular K+ or by veratridine to be directly and continuously monitored. The released ATP interacted with firefly luciferin and luciferase in the incubation medium to produce light which could be detected by a photomultiplier. The assay system was specific for ATP, in that similar concentrations of adenosine, AMP or ADP did not produce chemiluminescence. Moreover, the maximum peak of light emission correlated linearly with the concentrations of ATP present in the medium, so that semiquantitative estimates of ATP release could be made.Elevating the extracellular K+ concentration produced a graded release of ATP from synaptosomes. Rb+ also released ATP but Na+, Li+ and choline did not. The response to elevated K+ was not blocked by tetrodotoxin (TTX), indicating that this effect was not mediated by the opening of Na+‐channels in synaptosomal membranes.Veratridine (50 μM) caused a graded release of ATP which was larger and more prolonged than that caused by elevated K+. The release of ATP by veratridine was blocked by TTX indicating that the opening of Na+‐channels was involved. Neither veratridine nor elevated K+ released ATP from microsomal or mitochondrial fractions, showing that the release of ATP probably did not originate from microsomal, vesicular or mitochondrial contaminants of the synaptosomal preparation.Release of ATP by elevated K+ was diminished in a medium lacking CaCl+ or when EGTA was added to chelate Ca2+. In contrast, release by veratridine appeared to be augmented in Ca2+‐free media or in the presence of EGTA.The K+‐induced release of ATP, which is Ca2+ dependent, closely resembles the exocytotic release of putative neurotransmitters from presynaptic nerve‐terminals. On the other hand, the apparent lack of a Ca2+ requirement for veratridine's action suggests that this process could originate from other sites, or involve mechanisms other than conventional neurotransmitter release processes.
RESTITUTION OF CEREBRAL ENERGY STATE, AS WELL AS OF GLYCOLYTIC METABOLITES, CITRIC ACID CYCLE INTERMEDIATES AND ASSOCIATED AMINO ACIDS AFTER 30 MINUTES OF COMPLETE ISCHEMIA IN RATS ANAESTHETIZED WITH NITROUS OXIDE OR PHENOBARBITAL
Authors: Nordström C.‐H. , Rehncrona S. , Siesjö B. K. 
Published: October 2006

Abstract—Restitution of cerebral cortex concentrations of organic phosphates, glycolytic metabolites, citric acid cycle intermediates, associated amino acids, and ammonia, following a 30 min period of complete ischemia, was studied in rats anaesthetized with either 70% N2O or 150 mg·kg‐1 of phenobar‐bital.Following a 90 min period of recirculation the pattern of restitution was similar in the two groups. Thus, all animals showed recovery of phosphocreatine concentrations, restitution of the adenylate energy charge to about 99% of control, and disappearance of lactate accumulated during the ischemia. Analyses of glycolytic metabolites indicated inhibition of glycolysis at the phosphofructokinase step, possibly caused by accumulation of citrate. Measured citric acid cycle intermediates indicated extensive normalization of mitochondrial metabolism. Changes in amino acid concentrations consisted of a fall in glutamate concentration, a rise in aspartate/glutamate ratio, a fall in GABA concentration, and a rise in alanine concentration. However, ammonia concentration was close to normal, and the size of the amino acid pool did not change.It is concluded that although the results do not exclude damage to a small part of the neuronal population, they demonstrate that, irrespective of the type of anaesthesia used, the majority of brain cells must have survived 30 min of complete ischemia without signs of irreversible metabolic damage.
IN VITRO BIOSYNTHESIS OF TUBULIN ON TOTAL, FREE AND MEMBRANE‐BOUND POLYSOMES FROM THE DEVELOPING RAT BRAIN
Authors: Sato M. , Yoshida Y. , Takahashi Y. 
Published: October 2006

Abstract— Incorporation of [3H]leucine into tubulin and total protein was examined using a polysomal system from newborn (1‐day‐old). young (10‐day‐old) and adult (3‐month‐old) rat brains and cerebral cortices. The rate of tubulin biosynthesis (specific radioactivity) was always lower than that of total protein biosynthesis. No significant differences in the specific radioactivities of the synthesized total proteins were found between the newborn and young brain polysomal system, although young cerebral cortical polysomes were less active than newborn cerebral cortical polysomes. The adult brain (or cerebral cortical) polysomes were less active, about 20‐30% lower than the young brain (or cerebral cortical) polysomes. The incorporation of [3H]leucine into tubulin showed a progressive decrease in the polysomal systems isolated from the newborn, young and adult rat brains and cerebral cortices. These tendencies were similar in every cell sap taken from newborn, young and adult rat brain homogenates.In order to examine the relative activities of free and bound polysomes of the developing rat brain in tubulin biosynthesis. double‐labelling experiments were carried out. Labelled tubulin was purified by the assembly and disassembly method, followed by SDS gel electrophoresis, or by vinblastine precipitation method, followed by SDS gel electrophoresis; then identification by co‐electrophoresis with native brain tubulin, molecular weight determination and demonstration of specific aggregation in the presence of GTP followed. Free and bound polysomes showed approximately similar activities during tubulin biosynthesis. Furthermore, relative activities of tubulin biosynthesis by free and bound polysomes did not significantly change during development.
EXISTENCE OF ASCORBIC ACID AS AN ACTIVATOR OF THIAMINE DlPHOSPHATASE IN RAT BRAIN
Authors: Matsuda T. , Maeda S. , Baba A. , Iwata H. 
Published: October 2006

Abstract—The effect of the supernatant fraction (105,000 g for 60 min) of rat brain on the microsomal thiamine diphosphatase activity was examined. The thiamine diphosphatase activity was increased by addition of the supernatant fraction. The factor activating the enzyme was a heat‐stable and dialyzable substance. It caused lipid peroxidation in the microsomes and the increase of the enzyme activity was mediated through lipid peroxidation of the preparation. When the supernatant fraction was chromatographed on columns of Sephadex G‐25 and Dowex 1 × 2, the activator was eluted in fractions containing ascorbic acid. The inhibitory factor of ATPase present in the supernatant fraction was also eluted with the activator. The u.v.‐spectrum of the active fraction obtained by these chromatographies was the same as that of ascorbic acid. These findings indicate the existence of ascorbic acid as an activator of thiamine diphosphatase in rat brain and confirm the previous finding that the soluble factor inhibiting ATPase activity is ascorbic acid.
POST MORTEM STABILITY AND STORAGE IN THE COLD OF BRAIN ENZYMES
Authors: Puymirat J. , Javoy‐Agid F. , Gaspar P. , Ploska A. , Prochiantz A. , Agid Y. 
Published: October 2006

Abstract—Tyrosine hydroxylase (TH), glutamate‐decarboxylase (GAD) and choline acetyltransferase (CAT) were estimated in the striatum of rat brains kept at 20°C or 4°C for various periods of time up to 48 h after death. At 20°C TH and GAD activities decreased up to 4&50% of controls after 48 h; CAT activity was not affected. Maintenance of dead animals at 4°C completely (GAD and CAT) or partially (TH) prevented the decrease in enzyme activities. In a second series of experiments, TH, G A D and CAT activities were measured in striata (tissue or homogenate) stored immediately after death at different temperatures (4°C; ‐35°C; ‐70°C) for various time intervals up to 3 months. Storage of striata at 4°C induced a rapid decrease of all enzyme activities with time (GAD > CAT > TH). TH, GAD and CAT activities in striata kept at ‐35°C or ‐70°C were fairly stable. However, CAT activity was slightly decreased when the dissected striata were not homogenized; GAD activity was substantially reduced after 3 months at ‐35°C. Stability of TH, GAD and CAT activities were confirmed in homogenates of human caudate nucleus stored at ‐70°C for 1 month.If human enzymes behave similarly to the rat enzymes the following conclusions should be drawn: (1) brains should be obtained at autopsy within 8 h after death; (2) placement of dead bodies in the refrigerator should be done as soon as possible; (3) dissected brain structures (preferably as homogenates) should be stored at ‐70°C.
EFFECTS OF NERVE GROWTH FACTOR ON CYCLIC AMP LEVELS IN EMBRYONIC CHICK DORSAL ROOT GANGLIA FOLLOWING FACTOR DEPRIVATION
Authors: Skaper S. D. , Bottenstein J. E. , Varon S. 
Published: October 2006

AbstractNerve growth factor (NGF) at 10 B.U./ml produced a 5‐fold increase in the concentration of cyclic AMP 10min after addition to freshly excised embryonic chick dorsal root ganglia (DRG). The presence of NGF at 10 B.U./ml, but not 1 B.U./ml, over a 6 h incubation in nutrient‐free medium prevented this cyclic AMP increase when the DRG were again challenged with NGF (10 B.U./ml) after the 6 h. Incubation of DRG for 6 h at 37°C without NGF did not prevent the cyclic AMP response from occurring when NGF was presented at this time. The basal cyclic AMP concentration, however, decreased by 65–75% during the course of the 6 h incubation, and the continuous presence of NGF (10 B.U./ml) was unable to prevent this. When NGF was added to 6‐h NGF‐deprived DRG, the time for maximum cyclic AMP increase decreased from 15min to 6min with increasing NGF concentrations from 1 to 50 B.U./ml, although the relative magnitude of the cyclic AMP increase was essentially the same (approx 3‐fold) at these NGF concentrations.Attempts were made to correlate the cyclic AMP response in NGF‐deprived DRG with another rapid response resulting from administration of NGF to NGF‐deprived DRG, namely, the reactivation of hexose uptake. The cyclic AMP and permeation responses both occurred on the same time scale (5‐15 min), and both responded to increasing concentrations of NGF with a decreasing time to achieve maximal effect. A temporal relationship between cyclic AMP and membrane permeability was noted, but it could not be ruled out that it might reflect difficulties in methodology and/or inadequacy in current knowledge of the underlying mechanisms.
STUDIES ON AUTOIMMUNE ENCEPHALOMYELITIS IN THE GUINEA PIG—TIT. A COMPARATIVE STUDY OF TWO AUTOANTIGENS OF CENTRAL NERVOUS SYSTEM MYELIN1
Authors: Lebar René , Vincent Christine , Boubennec Elisabeth Fischer‐le 
Published: October 2006

Abstract— A new CNS myelin autoantigen(s) (referred to as M2), different from the encephalitogenic basic protein (BP), can be detected with guinea‐pig demyelinating and complement fixing (CF) sera raised against guinea pig CNS tissue or myelin (Lebaret al., 1976). M2 and BP were present in mouse, rat, rabbit, bovine and human CNS tissues when tested with guinea‐pig homologous specific antisera; they were not present in non‐CNS tissues. Both autoantigens were also detected in newborn guinea‐pig myelin and myelin‐like fractions.The CF activity of myelin with demyelinating (anti‐M2) sera was not altered by trypsin; however, absorption experiments showed that M2 was partly trypsin sensitive. Both antibodies against the trypsin sensitive and the trypsin resistant determinants of M2 were demyelinating. Both determinants of M2 were preselit in mouse, rat, rabbit, bovine‘and human CNS tissues and in guinea‐pig newborn myelin. CF BP activity of myelin was partially or even totally abolished by trypsin, but the persistent encephali‐togenicity of trypsin‐treated myelin could be attributed to non‐CF encephalitogenic peptides from BP.In accordance with recent work our results tend to support an inner localization of BP in myelin; M2, on the other hand, would be a surface antigen(s).
THE EFFECT OF MONOAMINE OXIDASE INHIBITORS ON SOME ARYLALKYLAMINES IN RAT STRIATUM
Authors: Philips S. R. , Boulton A. A. 
Published: October 2006

AbstractThe trace amines phenylethylamine, tryptamine, p‐tyramine and m‐tyramine have been measured in the striatum of both control and MAO‐treated rats. Dose‐response and time‐response studies have been carried out with clorgyline and deprenyl, inhibitors which preferentially inhibit the A and B forms of MAO, respectively, and with tranylcypromine and phenylethylhydrazine, which are used clinically in the treatment of depression. Phenylethylamine was increased by 1 mg/kg of deprenyl, but was unaffected by clorgyline at doses up to 50 mg/kg, while the tyramines and tryptamine were increased by low doses of clorgyline, but were increased only by much greater doses of deprenyl than those required to affect phenylethylamine.Phenylethylamine is oxidized by the B form of MAO, but tryptamine and the tyramines appear to be oxidized by both A and B MAO. The observed proportional increases in trace amine levels are much greater than those observed for the classical neurotransmitters, noradrenaline, dopamine and 5‐hydroxytryptamine. As these increases are differential, selective manipulation of trace amine concentrations is possible.
Human Brain Aldehyde Reductases: Relationship to Succinic Semialdehyde Reductase and Aldose Reductase
Authors: Hoffman Paula L. , Wermuth Bendicht , Wartburg Jean‐Pierre von 
Published: October 2006

AbstractHuman brain contains multiple forms of aldehyde‐reducing enzymes. One major form (AR3), as previously shown, has properties that indicate its identity with NADPH‐dependent aldehyde reductase isolated from brain and other organs of various species; i.e., low molecular weight, use of NADPH as the preferred cofactor, and sensitivity to inhibition by barbiturates. A second form of aldehyde reductase („SSA reductase”) specifically reduces succinic semialdehyde (SSA) to produce γ‐hydroxybutyrate. This enzyme form has a higher molecular weight than AR3, and uses NADH as well as NADPH as cofactor. SSA reductase was not inhibited by pyrazole, oxalate, or barbiturates, and the only effective inhibitor found was the flavonoid quercetine. Although AR3 can also reduce SSA, the relative specificity of SSA reductase may enhance its in vivo role. A third form of human brain aldehyde reductase, AR2, appears to be comparable to aldose reductases characterized in several species, on the basis of its activity pattern with various sugar aldehydes and its response to characteristic inhibitors and activators, as well as kinetic parameters. This enzyme is also the most active in reducing the aldehyde derivatives of biogenic amines. These studies suggest that the various forms of human brain aldehyde reductases may have specific physiological functions.
Rat, Mouse, and Guinea Pig Brain Development and Microtubule Assembly
Authors: Lennon A. M. , Francon J. , Fellous A. , Nunez J. 
Published: October 2006

Abstract:The development of in vitro microtubule assembly and of tubulin concentration have been studied during brain maturation in the mouse and the rat, two species which have postnatal brain development, and in one species which is mature at birth, the guinea pig. (a) The rate of tubulin assembly is very slow soon after birth in both the mouse and rat; it increases progressively with age until adulthood. In contrast, in the guinea pig this rate is maximal at birth and slower rates are seen only at foetal stages. (b) Postnatal changes in the lag period of assembly and in the minimal concentration of tubulin (Cc) required to obtain in vitro assembly are seen in the mouse and the rat; in contrast these parameters are constant at all postnatal stages in the guinea pig with longer lag periods and lower Cc values being seen only at foetal stages. (c) Maximal rates of assembly, minimal lag periods, and minimal Cc values are restored after addition of microtubule‐associated proteins to foetal guinea pig or young mouse and rat preparations, suggesting that the difference in the kinetic parameters of assembly between these species depends on differences in the concentration or activity of these proteins. (d) Maximal tubulin concentrations are observed before birth in the guinea pig and approximately at day 10 in the rat and mouse. Lennon A. M. et al. Rat, mouse, and guinea pig brain development and microtubule assembly. J. Neurochem.35, 804–813 (1980).
Choline Uptake by the Neuroblastoma X Glioma Hybrid, NG108‐15
Authors: McGee Richard 
Published: October 2006

Abstract:The neuroblastoma X glioma hybrid clone NG108‐15 is able to release acetylcholine upon depolarization and form cholinergic neuromuscular synapses in culture. Normal functioning of cholinergic synapses is thought to be dependent on the ability of a neuron to take up extracellular choline, since neurons are unable to synthesize choline de novo. For these two reasons it became important to characterize the choline uptake system of NG108‐15 cells. The uptake system appears to bear little if any resemblance to the Na+‐dependent high‐affinity choline uptake system normally associated with cholinergic neurons. Although the cells appear to possess both high‐ and low‐ affinity choline uptake systems, neither system is dependent on Na+ and uptake actually is increased about 60% by the substitution of sucrose for NaCl. Acetylcholine synthesis also is not dependent on Na+, since sucrose, substituted for NaCl, also stimulates acetylcholine synthesis. Changes in the concentrations of the other ions in the uptake medium have little effect on uptake, with the exception that elevated Ca2+ or Mg2+ reverses the stimulation of choline uptake produced by substitution of sucrose for NaCl. Choline uptake is inhibited by hemicholinium‐3, but only at high concentrations of the drug (IC50= 30–80 μm). The metabolic poisons cyanide and iodoacetate inhibit uptake by only 30‐40%. Growth of the cells in N6,O2′ dibutyryladenosine‐3′,5′‐cyclic monoposphate, which promotes functional and morphological differentiation of the cells, decreased slightly the total amount of choline taken up but had no additional effect on the uptake system. Thus, it appears that NG108‐15 cells are capable of forming functional cholinergic synapses with muscle cells even though the neuroblastoma does not possess the high‐affinity choline uptake system normally associated with cholinergic neurons.
Glial Cell Markers in the Reeler Mutant Mouse: A Biochemical and Immunohistological Study
Authors: Ghalidour M. S. , Derer P. , Labourdette G. , Delaunoy J. P. , Langley O. K. 
Published: October 2006

Abstract:The glial cell contents of S lOO protein, 2′3′‐cyclic AMP, 3′‐ phosphohydrolase (CNP), isoenzyme II of carbonic anhydrase (CAII) and butyrylcholinesterase (BuChE) were biochemically determined in the cerebellum and cerebrum of the reeler mutant mouse. Astrocytes and oligodendrocytes, shown by this study, contain abnormal amounts of these components. The CAII concentration was significantly increased in the particulate fraction of the reeler cerebellum and cerebrum (by 50% and 89%, respectively). The BuChE specific activity was greatly increased in the reeler, by 120% for cerebellum and by 40% in cerebrum. In contrast, the SlOO protein concentration was reduced in the reeler cerebellum by 40% and by 25% in cerebrum, while the CNP specific activity increased by 30% in the reeler cerebellum. In addition, the glial cell distribution was studied by immunohistological techniques with antibodies directed against S 100 protein, glial fibrillary acidic protein (GFA) and CAII. Apparently the density of glial cells is not significantly affected. However, the Golgi epithelial cells were usually abnormally placed and their Bergmann fibres were less well developed.
Effects of Preweaning Undernutrition and Continued Postweaning Protein Deficiency or Nutritional Rehabilitation on Polyphosphoinositides in Rat Brain
Authors: Uma S. , Ramakrishnan C. V. 
Published: October 2006

Abstract:Metabolically inert polyphosphoinositides seem to play an important role in the structural development of neurons, glia, and myelin. The metabolically active pool of Phlpp appears to be important for the functional development of glia and myelin during the post‐weaning period, whereas Phlp seems to be more important for the functional development of neurons during the preweaning period. Neonatal undernutrition reduces the concentrations of structural polyphosphoinositides and metabolic PhIp while metabolic Phlpp remains unaltered. These effects can be reversed by postweaning nutritional rehabilitation. A continued postweaning protein deficiency of neonatally undernourished rats affects structural Phlpp more than PhIp. Metabolically active Phlpp is drastically reduced.