bluuebunny/crossref_metadata_2025_split huggingface dataset:
DETERGENT‐LIKE ACTION OF TETRAPHENYLBORATE ON PHOSPHOLIPID LABELLING IN GUINEA PIG CORTEX SUBFRACTIONS1
Authors: Schacht J. , Agranoff B. W. 
Published: October 2006

Abstract—The addition of 2 × 10−4m sodium tetraphenylborate to particulate preparations of guinea pig cerebral cortex increases labelling of phosphatidic acid from γ‐[32P]‐ATP two‐ to four‐fold. The effect ‘was observed in all subcellular fractions studied (nuclear, synaptosomal, mitochondrial and microsomal) and is not blocked by the addition of atropine. Changes in phospholipid labelling similar to those induced by tetraphenylborate can be demonstrated with sodium dodecyl sulphate or sodium desoxycholate. It is suggested that tetraphenylborate stimulates lipid labelling by a detergent‐like activation of diglyceride kinase.
EFFECT OF NEUROTRANSMITTERS ON PHOSPHOLIPID METABOLISM IN RAT CEREBRAL‐CORTEX SLICES—CELLULAR AND SUBCELLULAR DISTRIBUTION1
Authors: Abdel‐Latif A. A. , Yau S.‐J. , Smith J. P. 
Published: October 2006

Abstract— Young rat cerebral‐cortex slices were incubated with 32Pi in the absence and presence of ACh plus eserine, norepinephrine, dopamine or serotonin for 1 h. their cellular and subcellular fractions were isolated, and the specific radioactivities of the various phospholipids determined.In the neuronal‐ and astroglial‐enriched fractions ACh plus eserine increased the 32P‐labelling of phosphatidyl inositol (PhI) phosphatidic acid (PhA) and phosphatidylcholine (PhC) by increments which ranged from 108 per cent for PhI to 30 per cent for PhC and in the presence of norepinephrine or dopamine these increments ranged from 180 per cent for PhI to 29 per cent for PhC.In the subcellular fractions ACh plus eserine exerted maximal stimulatory effect on the labelling of the synaptosomal phospholipids, which was 88 per cent for PhI and 79 per cent for PhA, followed by those of microsomes, mitochondria and nuclei.ACh plus eserine exerted no effect on [l4C]glucose incorporation, but inhibited the incorporation of [14C]glycerol into phospholipids by amounts which ranged from 30 per cent for PhI to 3 per cent for PhE.Although the rate of incorporation of 32Pi into phospholipids of 0.2 mm slices was higher than that of the 0.5 mm slices the stimulatory effect of ACh plus eserine on the 32Pi incorporation into the lipids of the latter was higher.When neuronal‐ and astroglial enriched fractions were first isolated from the cerebra then incubated with 32Pi or [14C]choline, labelling of phospholipids in the neuronal fraction was higher than that of the astroglial fraction; however, ACh plus eserine had no effect on the incorporation of 32Pi into the lipids of either fraction.ACh plus eserine stimulated the activity of phosphatidic acid phosphatase in the various subcellular fractions by increments which ranged from 13 per cent in nuclei to 37 per cent in microsomes.It was concluded that the nonspecific localization of the neurotransmitter effect could be due to the widespread distribution of the enzymes which appear to be responsive to cholinergic and adrenergic neurotransmitters.
THE ISOLATION AND PROPERTIES OF LARGE BASIC PEPTIDES FROM BOVINE SPINAL CORD
Authors: Eylar E. H. , Hashim G. A. 
Published: October 2006

Abstract— Two basic peptides (B1 and B2) were derived from bovine spinal cord following in situ proteolysis at 37°C for 10–24 h. These peptides do not arise as degradation products from the A1 protein as shown by amino acid composition and end group analysis; rather they appear to originate from some larger basic protein in the spinal cord having similarities to the P2 protein, a basic protein found in peripheral nerve myelin. The peptides were purified following defatting, acid extraction, and ammonium sulphate fractionation, by chromatography on Amberlite IRC‐50 resin using guanidinium chloride. The peptides, found generally in a 4:1 ratio of B1 to B2, appeared homogeneous on gel electrophoresis and immunodiffusion. Approximately 25–60 mg of peptides was obtained per 100 g wet spinal cord.In contrast to the basic A1 protein from myelin, neither of these peptides nor their pepsin digests were encephalitogenic. They do not cross‐react immunologically with the basic A1 protein, but cross‐react with each other. These peptides further differ from the A1 protein in their tryptic peptide map, size (B1, 63 residues; B2, 54 residues), and composition particularly the high lysine: arginine ratio, and low histidine content. Like the A1 protein, however, they contain a tryptophan residue and a blocked NH2‐terminal amino acid; peptide Bl has COOH‐terminal valine. It was concluded that the basic peptides represent a fragment of a hitherto unidentified protein(s) of the nervous system.
HIGH AFFINITY UPTAKE OF l‐GLUTAMINE IN RAT BRAIN SLICES
Authors: Balcar V. J. , Johnston G. A. R. 
Published: October 2006

Abstract—l‐Glutamine is taken up into rat brain slices by a specific‘high affinity’uptake system (Km 52 μm) which is not influenced by high concentrations of l‐glutamate and l‐asparagine. The uptake system appears to be associated with cellular structures that do not survive homogenization under conditions which yield synaptosomes. The‘high affinity’uptake of glutamine is dependent on the external sodium ion concentration and can be inhibited by p‐chloromercuriphenylsulphonate, amino‐oxyacetic acid, ouabain, dibenamine and allylglycine. The effects of several inhibitors indicate that l‐asparagine uptake is mediated by a system different from the‘high affinity’system mediating l‐glutamine uptake.
EFFECTS OF CHRONIC PORTO‐CAVAL ANASTOMOSIS ON BRAIN TRYPTOPHAN, TYROSINE AND 5‐HYDROXYTRYPTAMINE
Authors: Curzon G. , Kantamaneni Bharati D. , Fernando J. C. , Woods Margaret S. , Cavanagh J. B. 
Published: October 2006

Abstract—Three weeks after porto‐caval anastomosis, tryptophan and 5‐hydroxyindolylacetic acid concentrations were‐greatly increased in rat brain regions. 5‐Hydroxytryptamine showed smaller increases. Midbrain tyrosine and muscle tyrosine and tryptophan concentrations were also increased. Striatal dopa‐mine concentration was not significantly changed. Unlike previous results from acute liver failure, brain tryptophan changes in this chronic study did not simply reflect plasma‐free tryptophan changes. Midbrain tryptophan/plasma‐free tryptophan ratio and midbrain tyrosine/plasma tyrosine ratio both rose, suggesting increased effectiveness of uptake of these amino acids from plasma by brain. Corresponding muscle/plasma ratios were unaltered by the porto‐caval anastomosis. Uptake of tryptophan from buffer by cerebral cortex slices was unaffected. Results on control animals illustrate the importance of plasma‐free tryptophan in the normal physiological control of brain tryptophan.
STEARYL COENZYME A DESATURASE ACTIVITIES IN RAT BRAIN MICROSOMES
Authors: Pullarkat R. K. , Reha H. 
Published: October 2006

Abstract—A quantitative assay for the rat brain microsomal stearyl CoA desaturase is described. The method was used to determine the developmental pattern and regional distribution of the desaturase in rat brain. Even though the specific activity of the enzyme decreased to one‐third from 8 to 60 days of age, the total activity per brain remained the same. The regional distribution of the activity in adult brain was of the order midbrain > medulla oblongata > cerebral hemispheres > cerebellum, with midbrain activity being about twice as that of the cerebellum.
SUBCELLULAR LOCALIZATION AND PROPERTIES OF A CHOLINERGIC RECEPTOR ISOLATED FROM HOUSEFLY HEADS
Authors: Donnellan J. F. , Jewess P. J. , Cattell K. J. 
Published: October 2006

Abstract—Protein(s) possessing the ligand‐binding properties expected of the insect cholinergic receptor were demonstrated in both aqueous and chloroform‐methanol extracts of an 80,000 g supernatant obtained from frozen housefly heads. There is reasonable correlation in both the properties and concentration of the housefly head cholinergic receptor in these radically different extracts.Binding constants for decamethonium, acetylcholine, nicotine and atropine have been determined with aqueous housefly head extracts using an ultrafiltration assay. These observations are taken as further evidence that the cholinergic receptor in the insect central nervous system differs in specificity to the more widely studied nicotinic and muscarinic cholinergic receptors from vertebrates.
THE EFFECTS OF HYPERKETONEMIA ON GLYCOLYTIC INTERMEDIATES IN THE DEVELOPING RAT BRAIN
Authors: Ozand P. T. , Stevenson J. H. , Tildon J. T. , Cornrlath M. 
Published: October 2006

Abstract— Newborn rats from dams fed on a high fat diet developed increased ketonemia and significant hypertriglyceridemia i.e. “hyperketonemic pups”. This perinatal metabolic stress led to an alteration in the developmental pattern of glycolytic intermediates in their brains.In control rats, the concentration of glucose 6‐phosphate (G6P) in the brain was high at birth, and gradually decreased to adult values by the third week of life. In contrast, the fructose‐1,6‐diphosphate (FDP) concentration was low at birth and increased thereafter. The lactate concentration was also high at birth but decreased to the adult level by the first day of life. In the brains of control pups, lactate and pyruvate concentrations remained relatively constant during the first 3 weeks of life.In the brains of hyperketonemic pups, the concentration of G6P was the same as in the control animals at birth but decreased significantly during the first days of life. During early development the concentrations of FDP and pyruvate were significantly lower and the concentration of lactate, higher in the hyperketonemic pups as compared to the control group. The alteration in the concentration of these glycolytic intermediates in the brains of hyperketonemic pups indicated a change in the developmental pattern of glycolysis. The ratio of [lactate]/[pyruvate] also suggested an increased cytoplasmic redox potential in the brains of hyperketonemic pups during the first week of life.
TRANSPORT OF LEUCINE AND SODIUM IN CENTRAL NERVOUS TISSUE: STUDIES ON RETINA IN VITRO1
Authors: Ames A. , Parks J. M. , Nesbett F. B. 
Published: October 2006

Abstract—Unidirectional leucine fluxes were measured in isolated rabbit retina maintained under steady state conditions in medium resembling CSF but with leucine varied from 2 to 20,000 μM. At physiological leucine concentration (11 μM), 1/2 time for outward transport was 88 s and intracellular fluid was cleared of Isotopically labelled leucine at 2.3ml/g dry wt./min; 1/2 time for inward transport was 16 s and interstitial fluid was cleared at 7.5 ml/g dry wt./min. The rate of leucine influx corresponded quite well with its rate of disappearance from the intracellular fluid, over a wide range of concentrations. Exchange diffusion was demonstrated for transport in both directions. There was competition by other amino acids, but no interaction between Na+ and leucine transport could be demonstrated. Kinetic analysis indicated the presence of more than one transport system for leucine. There was an unexpected fall in the efflux coefficient, with reduction in leucine concentration at the lower end of the concentration range, for which an explanation is proposed. Under control conditions, 1/2 time for efflux of intracellular 24Na+ was about 0.9 min. With intracellular Na+ increased 4 fold, l/2 time for efflux was slightly reduced. Problems encountered in measuring fluxes in organized tissue are discussed.
EFFECT OF HYPOCAPNIA, HYPERCAPNIA, AND BLOOD PRESSURE ON NADH FLUORESCENCE, ELECTRICAL ACTIVITY, AND BLOOD FLOW IN NORMAL AND PARTIALLY ISCHEMIC MONKEY CORTEX
Authors: Sundt T. M. , Anderson R. E. , Sharbrough F. W. 
Published: October 2006

Abstract—Nicotinamide adenine dinucleotide fluorescence, cortical reflectance, cortical blood flow, and electroencephalograms were recorded from squirrel monkey brains before, during, and after focal transient cerebral ischemia produced by the temporary clipping of the middle cerebral artery. After release of the occluding clip, the monkeys were followed through an N2‐breathing cycle and then to death from anoxia. The effects of controlled variations in arterial carbon dioxide tensions (Paco2) and mean arterial blood pressures (MABP) were investigated in normal and in ischemic brain. In normal brain, with preserved autoregulation, NADH fluorescence was constant through a wide range in Paco2, MABP, and cortical blood flow. In ischemic brain, NADH levels increased, correlated closely with decreased cortical blood flow and EEG abnormalities, and became dependent on MABP. Artifacts in fluorescent measurements were reduced by: monochromators for excitation, emission, and reflected light; low intensity vertical excitation energy and high sensitivity recording instrumentation; and a small avascular (123 μm) field.
CYSTATHIONINE SYNTHESIS AND DEGRADATION IN BRAIN, LIVER AND KIDNEY OF THE DEVELOPING MONKEY
Authors: Sturman J. A. , Gaull G. E. , Niemann W. H. 
Published: October 2006

Abstract— The concentration of cystathionine, along with the specific activities of the enzymes involved in its synthesis and degradation, cystathionine synthasc and cystathionase, respectively, have been measured in brain, liver and kidney of the developing Rhesus monkey from mid‐gestation, through birth and neonatal life, to maturity. The concentration of cystathionine and the specific activity of cystathionine synthase are low in fetal brain. Both parameters increase slowly after birth and reach values found in adult brain at approx 3 months of postnatal age. The activity of cystathionase in brain is low throughout development.Liver provides a direct contrast in that the concentration of cystathionine and the specific activity of cystathionine synthase are high in the fetus, decreasing rapidly after birth to values found in the adult by 2 weeks of postnatal age. Cystathionase activity is low in fetal liver and increases slowly after birth reaching values found in adult liver after 2–3 months. Kidney has no more than trace amounts of cystathionine throughout development, higher activity of cystathionine synthase in the fetus than in the adult and high, unchanged activity of cystathionase throughout the period of development studied.These results indicate that the high concentrations of cystathionine found in primate brain are reached postnatally and suggest that this high concentration of cystathionine may be associated with the functioning of mature brain.
ENZYMES ASSOCIATED WITH THE METABOLISM OF CATECHOLAMINES, ACETYLCHOLINE AND GABA IN HUMAN CONTROLS AND PATIENTS WITH PARKINSON'S DISEASE AND HUNTINGTON'S CHOREA
Authors: McGeer P. L. , McGeer E. G. 
Published: October 2006

Abstract—Tyrosine hydroxylase (TH), dopa decarboxylase (DDC), glutamic acid decarboxylase (GAD), choline acetyltransferase (CAT), and acetylcholinesterase (AChE) were measured in 18–55 areas of brain from humans post mortem. Individuals meeting sudden and unexpected death (22), patients dying in hospital with non–neurological illness (6), Parkinson's disease (12), Huntington's chorea (8), terminal coma (6) or head injury (2) were included in the series. The absolute values obtained compared favourably with some previous human studies where high values for these enzymes were obtained, as well as with monkey and baboon data. The regional distributions of the enzymes were also comparable to those previously reported in human and animal studies. A number of important points with regard to human tissue seemed to emerge from the study. The mode of death was not a factor in enzyme levels in non–neurological and non‐coma cases. Post mortem delay did not seem to be a major factor either even though a substantial decline in GAD, TH and DDC could be demonstrated in rats left several hours between sacrifice and removal of the brain for assay. Age had a highly significant effect in certain areas of brain. The decline typically followed a curvilinear pattern (activity = A/age + B with the sharpest drops being in the younger age groups). DDC seemed to be the enzyme most severely affected by age but all the enzymes showed declines in certain brain areas, while in other areas there was no significant decline. All the enzymes were very depressed by coma from illness except AChE. TH and DDC in the brain stem were, however, not affected in the head injury cases. The Parkinsonian cases showed a sharply decreased TH activity in the substantia nigra, caudate and putamen. There were decreases in GAD in the globus pallidus (GP) and substantia nigra with marginal decreases in the neostriatum. CAT levels in the extrapyramidal nuclei were normal. In Huntington's chorea there was a substantial decrease in GAD in all the extrapyramidal structures. There was a patchy loss of CAT in the neostriatum and locus coeruleus.
PRESENCE OF 15‐HYDROXY PROSTAGLANDIN DEHYDROGENASE, PROSTAGLANDIN‐Δ13‐REDUCTASE AND PROSTAGLANDIN E‐9‐KETO(α)‐REDUCTASE IN THE FROG SPINAL CORD
Authors: Bishai I. , Coceani F. 
Published: October 2006

AbstractMetabolism of prostaglandin E1 (PGE1) and F1α (PGF1α) was studied in the frog spinal cord, using a hemisected preparation in vitro and tissue homogenates (whole honiogenate and tissue fractions). In the intact tissue, PGE, was converted to three Metabolites, 1 to 111, whereas only Metabolites 11 and 111 werc detected in experiments with PGF1α. Work with tissue homogenatcs confirmed that PG transformation is enzymatic, and endproducts were identified as PGF1α (Metabolite 1), 15‐kcto metabolite (Metabolite 11) and 15‐keto‐13,14‐dihydro metabolite (Metabolite 111). The 15‐keto‐13,14‐dihydro metabolite was formed via the 15‐keto metabolite which is consistent with findings elsewhere. These results establish the presence in the frog spinal cord of two pathways for PG metabolism, consisting one of the 15‐hydroxy prostaglandin dehydrogenase (15‐PGDH) and the prostaglandin‐A13‐ reductase (13‐PGR), the other of the prostaglandin E 9‐keto(α)‐reductase (9K‐PGR). 9K‐PGR is regarded as an inactivating enzyme because amphibian spinal neurons are less responsive to PGF, than to PGE1. In the intact or in the homogenized tissue, PGE, is metabolized more efficiently by the 15‐PGDH/13‐PGR than by the 9K‐PGR route. The 15‐PGDH metabolizes PGE, more readily than PGF1α. The present findings, together with the previous demonstration of active PG synthesis in the tissue and the potent actions of exogenous PGs, strongly suggest that the PGs play an important role in the function of neurons in the frog spinal cord.
HYPOXIC SURVIVAL OF NORMOGLYCAEMIC YOUNG ADULT AND ADULT MICE IN RELATION TO CEREBRAL METABOLIC RATES12
Authors: Berlet H. H. 
Published: October 2006

AbstractThe hypoxic tolerance and the cerebral metabolic rates (CMR) of young adult mice (20 to 25 g, 4 to 5 weeks old) and adult mice (30 g and above, 6 to 7 weeks old), respectively, were determined and their interrelationship was evaluated. CMRs increased from 25 mmol ‐ P/kg.min to 38 mmol/kg.min as the animals grew older from young to full adulthood. Concurrently the tolerance to aerogcnic hypoxia (5% O2‐95%j N2) declined. The effects of hypoxia on the cerebral energy metabolism were greater in adult than in young adult animals. It is concluded that the full metabolic maturation of the brain is reached in adult animals only. They become more dependent on an adequate oxygen supply as the aerobic activity of the energy metabolism of the brain is further increasing.Hypoxic gasping occurred while the pool of cerebral energy reserves was still far from being depleted. A failure to utilize energy reserves rather than their exhaustion is suggested as the ultimate cause of death from hypoxia. An acid‐soluble form of glycogen or related polyglucan was found in addition to the usual amounts of insoluble glycogen. It was utilizcd rapidly during hypoxia and ischaemic anoxia and it may, therefore, constitute an additional source of carbohydrate substrates in thc brain.
THE INFLUENCE OF PORTOCAVAL ANASTOMOSIS ON THE METABOLISM OF LABELLED OCTANOATE, BUTYRATE AND LEUCINE IN RAT BRAIN
Authors: Cremer J. E. , Teal H. M. , Heath D. F. , Cavanagh J. B. 
Published: October 2006

Abstract—Rats were given a portocaval anastomosis and 3 weeks later, when the only ultrastructural change in the CNS is watery swelling of astrocytes, several aspects of brain metabolism were studied. The uptake of leucine by the brain, its incorporation into protein and its oxidation were followed after the simultaneous injection of a mixture of L‐[114C]leucine and L‐[4,5‐3H]leucine. The concentration of leucine in blood was lowered in the operated animals whereas in brain it was increased. The specific radioactivity of leucine in the brain was comparable to values in control animals and there was no evidence of a decrease in incorporation of [1‐14C]leucine into brain proteins over the short experimental time period studied. The only difference from the controls in the oxidation of [4,5‐3H]leucine was a greater accumulation in glutamine. The amount of glutamine in the brains of the operated animals had increased 4‐fold at the time of the metabolic studies.From dual‐labelled experiments in which a mixture containing [1‐14C]butyrate and L‐[4,5‐3H]leucine was injected intravenously, it was shown that, in both control and operated animals, the pools of brain glutamate and glutamine labelled from butyrate were metabolically distinct from those labelled from leucine. The total radioactivity appearing in brain from [1‐14C]butyrate was markedly reduced in operated animals, but the radioactivity from L‐[4,5‐3H]leucine was not.The metabolism of [1‐14C]octanoate was compared with that of [1‐14C]butyrate. In control animals the labelling of metabolites was almost identical with either precursor. In operated animals there was no reduction in the uptake of [1‐14C]octanoate into the brain. There was evidence that the size of the glutamine pool labelled, relative to glutamate, was increased but that it had a slower fractional turnover coefficient. A link between astroglial changes and an impairment to the carrier mechanism for transport of short chain monocarboxylic acids across the blood‐brain barrier is suggested.
LYSINE METABOLISM IN THE RAT BRAIN: BLOOD—BRAIN BARRIER TRANSPORT, FORMATION OF PIPECOLIC ACID AND HUMAN HYPERPIPECOLATEMIA
Authors: CHANG YUNG‐FENG 
Published: October 2006

Abstract—Through the use of intravenous pulse injection of L‐[U‐14C] lysine, the blood‐brain barrier transport of L‐lysine was studied. The uptake of L‐lysine plus metabolites in the brain remained essentially unchanged at approx 0.002–0.005 nmol/g in the low dose (3μg per kg body weight) injection, and 20–40 nmol/g in the high dose (30 mg/kg) injection throughout the time intervals of up to 60 min. The uptake of L‐lysine plus metabolites in the heart, however, decreased substantially from 0.03 to 0.003 nmol/g in the low dose injection and from 320 to 62 nmol/g in the high dose injection. The plasma to heart uptake ratio only decreased slightly through the 60 min period: from 6 to 2 in either the low or high dose L‐lysine injection. The plasma to brain uptake ratio, however, decreased rapidly from a high of 62 to a low of about 4 in either the low or high dose injection throughout the 60‐min time course. Study of labeled L‐pipecolate formation in the plasma and individual organs indicates that this compound was formed only in the brain to a significant level within 0.5 min of14C‐L‐lysine intravenous pulse injection. Labeled pipecolate was recovered from heart, liver, kidney and plasma in significant quantities only at 2 min or later after pulse‐injection. It is concluded that the blood‐brain barrier of L‐lysine in the rat is not particularly strong and that the rat brain may be primarily responsible for L‐pipecolate synthesis from L‐lysine. The possible etiology of human hyperpipecolatemia is also discussed in light of the current findings.