bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE BLOCKAGE OF AXOPLASMIC FLOW OF PROTEINS BY COLCHICINE AND CYTOCHALASINS A AND B
Authors: McGregor A. M. , Komiya Y. , Kidman A. D. , Austin L. 
Published: October 2006

Abstract— Colchichine blocks axoplasmic flow of proteins in chicken sciatic nerve. The slow component is more effectively blocked than the fast. The colchicine effect on slow flow is independent of the time delay between colchicine injection and that of the [14C]‐leucine used to measure flow, over a period extending from 2 h after to 9 days before the leucine. It is still effective, but to a lesser degree, after a period of 27 days. There is little effect on the fast component when the colchicine is administered after leucine. When given before leucine the effect is not pronounced up to a time interval of 1 day. Maximum blockage was obtained with longer intervals of up to 27 days. These results are discussed in relation to the involvement of the microtubules in both slow flow and rapid flow.The effect of both cytochalasins A and B on slow and rapid protein flow has also been studied. Neither drug had any significant effect on slow flow. Cytochalasin A reduced the amount of protein flowing at the rapid rate to a small extent when administered 2 h before [14C]leucine. Cytochalasin B also caused a similar reduction and this effect was independent of dose over the ranges of doses used. The cytochalasin B diminished the incorporation of amino acid into protein in the spinal cord and it has been concluded that these results are due to a membrane effect which reduces uptake of amino acid rather than a direct effect on neurofilaments in the axons.
ADENOSINE 3′,5′‐MONOPHOSPHATE IN GUINEA PIG CEREBRAL CORTICAL SLICES: EFFECT OF BENZODIAZEPINES
Authors: Schultz J. 
Published: October 2006

AbstractSeveral benzodiazepines, diazepam, chlordiazepoxide, desmethyldiazepam, methyloxazepam and oxazepam, potentiate the accumulation of cyclic AMP elicited by histamine and histamine: noradrenaline in cerebral cortical slices of guinea pig. In addition, these drugs increase basal levels of cyclic AMP by about 100 per cent. When adenosine is used to stimulate cyclic AMP formation only diazepam, desmethyldiazepam and methyloxazepam are increasing cyclic AMP levels significantly over respective controls. The order of potency is: diazepam > desmethyldiazepam > methyloxazepam > oxazepam > chlordiazepoxide. Diazepam decreases the rate of degradation of cyclic AMP after removal of the stimulatory agents (histamine : noradrenaline). Dose response curves for diazepam under two stimulatory conditions are shown. A significant effect is obtained at 50 μm‐diazepam and an ED50 of 40 μm is calculated with histamine as the stimulatory agent. When cyclic AMP formation is elicited by histamine : noradrenaline a significant effect of diazepam is seen at 10 μm and an ED50 of 16 μm is obtained. These results lend support to the hypothesis that the psychotropic action of the benzodiazepines may, at least in part, involve the cyclic AMP generating systems of the central nervous system.
INFLUENCE OF EARLY VISUAL DEPRIVATION ON REGIONAL ACTIVITY OF BRAIN ATPases IN DEVELOPING RATS1
Authors: Meisami E. , Timiras P. S. 
Published: October 2006

AbstractThe effects of light deprivation from birth to 40 days of age on the development of Na‐K‐ATPase and Mg‐ATPase activity, enzymes significantly involved in cerebral energy exchange, ion transport, and synaptic function, were investigated in visual and non‐visual brain areas of the rat. Although both enzymes generally showed a progressive depression with age in light‐deprived rats, Na‐K‐ATPase was more depressed than Mg‐ATPase, and significant effects were confined to the superior colliculi, visual cortex, frontal cortex and hypothalamus. A disparate developmental pattern was evidenced in Na‐K‐ATPase activity in the visual cortex, where it was higher than control values at day 10 but lower by day 40, and in the hypothalamus, where it was lower on days 10 and 25 but significantly higher on day 40. The depression of Mg‐ATPase in the hypothalamus of light‐deprived rats at all ages and the activation of Na‐K‐ATPase in this structure is interpreted to mean that discrete alterations may have occurred in neurosecretory functions of the hypothalamus, known to be responsive to light. Transferring dark‐reared animals to normal light‐cycle conditions at day 25 affected only Mg‐ATPase in the visual cortex and Na‐K‐ATPase in the hypothalamus, both enzymes showing a significant increase by day 40 over values in continually light‐deprived animals. These findings confirm that early light deprivation is associated with important biochemical and neuroendocrine changes that persist into adulthood.
PROTEIN AND PEPTIDE HYDROLASES OF THE RAT HYPOTHALAMUS AND PITUITARY
Authors: Marks N. , Galoyan A. , Grynbaum Alice , Lajtha A. 
Published: October 2006

AbstractPeptide and peptidyl‐peptide hydrolase activities were measured in the cerebral cortex, adenoand neurohypophysis, anterior and posterior regions of the hypothalamus to assess regional differences in peptide hormone turnover. In general all enzyme activities were higher in the pituitary except for the monoacyl arylamidase which was lower, and neutral proteinase which was distributed more evenly in all regions. Of the enzymes measured the highest activities occurred in the presence of the di‐ and tripeptide substrates (aminopeptidases); this activity was some 20‐60‐fold higher than the acid and neutral proteinases. Comparison of the peptide‐amide substrates revealed the highest activity with the monoacyl derivative which was five‐fold higher than the dipeptidyl, and 50‐fold higher than the tripeptidyl (hormonal) factor Pro‐Leu‐Gly. NH2. Analysis of the breakdown products of the hormonal factor indicated inactivation by N‐terminal release of Pro, Leu with Gly. NH2 as the final product. Regional differences in enzyme content in neurosecretory areas suggest that this plays a role in the turnover of specific hormones.
EFFECTS OF ETHANOL ON SEROTONIN METABOLISM IN BRAIN
Authors: Tabakoff B. , Boggan W. O. 
Published: October 2006

AbstractThe effect of ethanol on serotonin metabolism in brains of mice was determined both after a single injection and ‘chronic’ administration of ethanol. Behavioral effects were also monitored.‘Chronic’ administration of ethanol by inhalation to mice resulted in an increased susceptibility to Metrazole induced seizures. This susceptibility was evident for 48 h after ‘withdrawal’ of mice from ethanol chambers. No differences in brain 5‐HT levels between control and ethanol treated mice were evident during withdrawal. However, a significant elevation in brain 5‐HIAA levels was noted during this period. Short lived increases in brain 5‐HIAA levels were also noted after a single injection of ethanol. Ethanol treatment produced no significant changes in the activity of brain MAO, aldehyde dehydrogenase, or aldehyde reductase. Other mechanisms for ethanol induced increases in brain 5‐HIAA are discussed.
REGIONAL DISTRIBUTION OF HOMOCARNOSINE AND OTHER NINHYDRIN‐POSITIVE SUBSTANCES IN BRAINS OF MALNOURISHED MONKEYS1
Authors: Enwonwu C. O. , Worthington Bonnie S. 
Published: October 2006

Abstract—Eight male monkeys (Macaca nemestrina) aged 6–9 months were divided into two groups and fed either an adequate protein diet (20% casein) or a protein deficient diet (2% casein). After 3‐ 5 months of receiving the low protein diet, the malnourished monkeys showed extensive fatty metamorphosis of the liver cells, distorted patterns of plasma and hepatic free amino acid pools, and other features consistent with the diagnosis of protein‐calorie malnutrition. Examination of the cerebrum, cerebellum and brain stem in the malnourished animals revealed profound accumulation of 3‐methylhistidine, histidine and homocarnosine in all three regions. For histidine, the cerebral, cerebellar and brain stem levels in the protein deficient animals increased by 145, 104 and 101 per cent over levels observed in corresponding regions of the brain in well‐fed monkeys. Similarly, there were significant elevations in homocarnosine contents of the cerebrum (+ 99 per cent), cerebellum (+ 140 per cent) and brain stem (+ 146 per cent) in comparison to levels in control animals. In contrast, the levels of valine, serine and aspartic acid were markedly reduced in all three brain areas in the malnourished animals. Protein‐calorie deficiency also produced reductions in the brain levels of taurine, glutamic acid, isoleucine, leucine and threonine which varied in magnitude in the three major regions of the brain examined. These biochemical alterations which may in part underlie some of the psychomotor changes often observed in protein‐calorie malnutrition, were discussed not only in relation to the role of amino acids as precursors for the synthesis of neuroregulatory substances but also with due regard to the possibility that some of these ninhydrin‐positive substances such as GABA, homocarnosine, glycine and the dicarboxylic amino acids may possess neuroexcitatory or inhibitory properties in various parts of the central nervous system.
PURIFICATION AND PROPERTIES OF CHOLINE ACETYLTRANSFERASE FROM THE NERVOUS SYSTEM OF DIFFERENT INVERTEBRATES
Authors: Emson P. C. , Malthe‐Sosrenssen D. , Fonnum F. 
Published: October 2006

Abstract—Choline acetyltransferase has been purified from three invertebrate species, namely snail (Helix aspersa), cockroach (Periplaneta americana) and horse shoe crab (Limulus polyphemus.) All three enzymes followed a Theorell‐Chance enzyme mechanism with a sequential addition of the substrates. All three enzymes were activated by sodium and potassium chloride and inhibited by high concentrations of magnesium or calcium chloride. The apparent Km for choline and acetyl‐CoA was for snail: Kmch= 370 μm,KmAcetyl‐CoA= 51μm; cockroach:KmCh= 550 μm, KmAcely‐CoA= 16 μm horse shoe crab:KmCn= 2700 μm KmAcctyl‐coA= 68 μmCoA inhibited the enzymes competitively with respect to acetyl‐CoA and non‐competitively with respect to choline. Acetylcholine inhibited the enzymes competitively with respect to choline and non‐competitively with respect to acetyl‐CoA. All the enzymes were inhibited strongly by 5,5′‐dithiobis (2‐nitrobenzoate), iodoacetate, acryloylcholine, chloracetylcholine and 3‐bromacetonyltrimethyl‐ammonium. The enzymes were only weakly inhibited by the styrylpyridine derivatives. The isoelectric points were 5.3 and 5.0 for the horse shoe crab and cockroach enzymes respectively. All three enzymes showed low affinity for a cation‐exchanger (CM‐Sephadex).
ON THE MECHANISM OF STIMULATION OF AMP‐AMINOHYDROLASE ACTIVITY BY HEXOKINASE IN BRAIN TISSUE
Authors: Haroutunian A. V. , Buniatian H. Ch. 
Published: October 2006

Abstract—A hexokinase has been isolated from brain tissue on Sephadex G‐100 and DEAE cellulose which is similar to yeast enzyme in stimulating the AMP‐aminohydrolase activity of rat brain soluble fractions. This effect of hexokinase is influenced neither by N‐acetyl‐glucosamine nor noradrenaline. An isoenzyme of hexokinase isolated from brain tissue on DEAE cellulose, having properties similar to that of the muscle enzyme, has no effect on AMP‐aminohydrolase activity. The activating effect of yeast hexokinase is not due to its oligomeric structure. Enzyme subunits obtained by the treatment of native yeast enzyme by urea also activate AMP‐aminohydrolase of rat brain soluble fractions.
ASSOCIATION OF AXONALLY TRANSPORTED PROTEINS WITH GOLDFISH BRAIN MYELIN FRACTIONS
Authors: Elam J. S. 
Published: October 2006

Abstract—The presence of rapidly transported axonal proteins in purified preparations of myelin has been investigated in the goldfish visual system. Fish were injected intraocularly with 3H proline and contralateral optic tecta were pooled 8–12 h later for purification of myelin. Three purification procedures were employed using continuous and discontinuous gradients of sucrose and continuous gradients of CsCl. All of the myelin preparations were found to have physical, chemical and enzymatic properties attributable to relatively pure preparations of myelin. The goldfish myelin differed from mammalian preparations in having a slightly lower density and in containing an additional major protein of approx. 45,000 mol. wt. All of the myelin preparations retained relatively high levels of axonally transported radioactivity with specific radioactivities which ranged from 70 to 80 per cent of that of the whole tectal homogenate. Acrylamide gel analysis showed the myelin‐associated radioactivity to be confined to the higher molecular weight proteins with very little radioactivity associated with basic protein or proteolipid protein. Both the axonally transported radioactivity and the group of higher molecular weight proteins were found to be more concentrated in a myelin subfraction of relatively high density than in a subfraction of low density. The possible significance of the association of axonally transported proteins with myelin is discussed.
CHANGES IN CARBOHYDRATE SUBSTRATES, AMINO ACIDS AND AMMONIA IN THE BRAIN DURING INSULIN‐INDUCED HYPOGLYCEMIA
Authors: Lewis L. D. , Ljunggren B. , Norberg K. , Siesjö B. K. 
Published: October 2006

Abstract—The influence of insulin‐induced hypoglycemia upon carbohydrate substrates, amino acids and ammonia in the brain was studied in lightly anaesthetized rats, and the changes observed were related to the blood glucose concentration and to the EEG. Calculations from glucose concentrations in tissue, CSF and blood indicated the presence of appreciable amounts of free intracellular glucose at blood glucose concentrations above 3 μmol/g. When the blood glucose concentration fell below 3 μmol/g, there was no calculated intracellular glucose and decreases in the concentrations of glycogen, G‐6‐P, pyruvate, lactate and of citric acid cycle intermediates were observed. At blood glucose levels of below 1 μmol/g the tissue was virtually depleted of glycogen, G‐6‐P, pyruvate and lactate.When the blood glucose concentration was reduced below about 2·5 μmol/g there were progressive increases in aspartate and progressive decreases in alanine, GABA, glutamine and glutamate, and at blood glucose concentrations below 2 μmol/g the ammonia concentration increased. It is suggested that most of the changes observed can be explained as a result of a decreased availability of pyruvate and of NADH. The decrease in the concentration of free NADH was reflected in reductions of the lactate/pyruvate and malate/oxaloacetate ratios at an unchanged intracellular pH.Slow wave activity appeared in the EEG when the hypoglycemia gave rise to reduction of the intracellular glucose concentration to zero. Convulsive activity continued until carbohydrate stores in the form of glycogen and G‐6‐P were depleted. When this occurred the EEG became isoelectric. In all convulsive animals the concentration of the nervous system activity inhibitor, GABA, was decreased and stimulant, aspartate, was increased.
THE EFFECT OF γ‐AMINOBUTYRIC ACID ON BRAIN MITOCHONDRIAL ATP SYNTHESIS1
Authors: Lee L.‐W. , Liao C.‐L. , Yatsu F. M. 
Published: October 2006

Abstract—Rat brain mitochondrial ATP synthesis was studied by measuring labeled orthophosphate incorporation into ADP to form ATP. GABA stimulates ATP synthesis, and this effect requires glutamate since with GABA alone little ATP is formed. The significance of this effect by GABA is unclear, but the mechanism may relate to induction of conformational change or chelation of cation.
INCREASED CONCENTRATIONS OF ACIDIC METABOLITES OF DOPAMINE IN THE SUPERIOR CERVICAL GANGLION FOLLOWING PREGANGLIONIC STIMULATION IN VIVO
Authors: Pearson J. D. M. , Sharman D. F. 
Published: October 2006

Abstract—Evidence is presented for the presence of two acidic metabolites of dopamine, 3,4‐dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the sympathetic ganglia of some mammalian species other than ruminants. In the pig, electrical stimulation of the preganglionic nerves to the superior cervical ganglion results in a mean increase of 78 per cent in the concentration of HVA and a mean increase of 372 per cent in the concentration of DOPAC in this sympathetic ganglion. These results can be interpreted as further evidence for the involvement of dopamine in transmission at sympathetic ganglia.
POLYACRYLAMIDE GEL ELECTROPHORESIS OF RAT BRAIN ACETYLCHOLINESTERASE: ISOENZYMES OF NORMAL RAT BRAIN1
Authors: Vijayan V. K. , Brownson R. H. 
Published: October 2006

Abstract— Triton‐solubilized acetylcholinesterase (EC 3.1.1.7) of rat brain was submitted to vertical flatbed polyacrylamide gel electrophoresis. Three anodally migrating isoenzyme zones with low relative mobilities could be resolved, each of which on quantitative densitometry appeared to consist of more than one subzone. More than 50 per cent of the total AChE activity was exhibited by the isoenzyme zone closest to the origin (isoenzyme zone 3).Regional differences in AChE isoenzyme activity were quantitative only with the caudate‐putamen complex, midbrain, pons and medulla oblongata exhibiting relatively high content of the three isoenzymes and the cerebral cortex and olfactory bulb possessing weak isoenzyme activities. Intermediate levels of isoenzyme activities were observed in the cerebellum and hippocampus. In all areas examined, the relative percentage values for each isoenzyme remained constant. AChE isoenzymes from the forebrain, brain stem and cerebellum of 15‐ and 30‐day‐old rats appeared to have identical patterns. In brain stem, no quantitative differences could be detected in the isoenzyme activities between 15 and 30 days of age. At both ages, the isoenzymes of male and female rats did not show any qualitative differences.The single cholinesterase (EC 3.1.1.8) isoenzyme which could be identified in brain stem supernatants of 30‐day‐old rats was weakly reactive and appeared to have the same relative mobility as the major acetylcholinesterase zone, zone 3.Acetylcholinesterase isoenzymes failed to demonstrate any differential response toward varying concentrations of inhibitors and to changes in pH. While there were basic similarities in the acetylcholinesterase and cholinesterase isoenzyme patterns of brain, serum, liver, skeletal muscle and intestine, brain alone exhibited a marked preponderance of the acetylcholinesterase isoenzyme zone 3.
THE EFFECTS OF LITHIUM ON HIGH ENERGY PHOSPHATE AND GLUCOSE LEVELS IN THE RAT SUPERIOR CERVICAL GANGLION1
Authors: Organisciak D. T. , Klingman J. D. 
Published: October 2006

Abstract— The effects of acute treatment with lithium ion (25 mm) on the levels of ATP, phosphocreatine and glucose were measured in an in vitro preparation of rat superior cervical ganglion. Similar analyses were performed on ganglia from rats fed a chronic lithium diet (0.5 mm). Ganglia were excised and de‐sheathed, then stimulated (5 Hz) or rested for 20, 40 or 80 min in normal or lithium‐containing Krebs‐Ringer bathing solutions. Following freeze drying, enzymatic pyridine nucleotide methods were used to measure fluorometrically ATP, phosphocreatine and glucose on portions of a ganglionic perchloric acid extract.After 20 min of incubation, normal ganglionic contents of ATP and phosphocreatine were higher than the initial zero time levels. Incubation for periods longer than 20 min resulted in ATP and phosphocreatine levels which were lower than those at zero time. Stimulation of normal ganglia caused a decrease in the contents of high‐energy phosphates relative to those in the resting state. Except for the 20 min time period the ATP levels were lower than normal in ganglia from rats chronically fed lithium. Levels of ATP and phosphocreatine in ganglia acutely exposed to lithium were significantly lower than in both normal ganglia and ganglia from chronically‐treated rats. In comparison to normal ganglia, significantly lower levels of glucose were found only for stimulated ganglia acutely exposed to lithium.
CONTROL OF THE REDOX STATE OF THE PYRIDINE NUCLEOTIDES IN THE RAT CEREBRAL CORTEX. EFFECT OF ELECTROSHOCK‐INDUCED SEIZURES
Authors: Howse D. C. , Duffy T. E. 
Published: October 2006

Abstract—The concentrations of most of the intermediates of glycolysis and of the tricarboxylic acid cycle were determined in the cerebral cortex of rats, frozen 10 s after the induction of a generalized seizure by electroshock. The apparent equilibrium constant for the combined glyceraldehyde‐3‐phosphate dehydrogenase, 3‐phosphoglycerate kinase and lactic dehydrogenase reactions, i.e. Kapp= [Lactate] [3‐Phosphoglycerate] [ATP]/[Pyruvate] [Glyceraldehyde‐3‐phosphate] [ADP] [HPO24], was evaluated and found to be similar to the value reported for the in vitro system at pH 7. During an estimated 4–5‐fold increase in glycolytic flux imposed by the seizure, this system remained close to equilibrium. In control cortex the components of the aldolase reaction were deviated 80‐fold from equilibrium but shifted slightly toward equilibrium during the seizure. The components of the aspartate aminotransferase reaction were maintained in equilibrium in both the control and the seizure states.Of 4 reactions used to assess the cytoplasmic and mitochondrial redox states, only the lactic dehydrogenase reaction was considered reliable in the acutely changing situation of the seizure, and yielded a calculated decrease in the cytoplasmic [NAD+]/[NADH] ratio. This change, coupled with an observed decrease in the [ATP]/[ADP] [HPO24] ratio during the seizure, supports the concept that in brain, as in liver (Krebs & Veech, 1969), the phosphate potential determines the redox state of the tissue.
PURIFICATION OF RAT BRAIN CHOLINE ACETYLTRANSFERASE AND AN ESTIMATION OF ITS HALF‐LIFE
Authors: Wenthold R. J. , Mahler H. R. 
Published: October 2006

Abstract—Acetyl‐CoA:choline‐O‐acetyltransferase (ChAc, EC 2.3.1.6) was purified from rat cerebral cortex and its half‐life determined. The molecular weight of the enzyme under non‐denaturing conditions was estimated by gel filtration to be in the range of 60,000–65,000. On SDS acrylamide gels, the purified enzyme migrated as a single band with a molecular weight estimated as 62,000. The turnover rate of ChAc in the mature rat was determined by the double label method, employing l‐[1‐14C]leucine and l‐[4,5‐3H]leucine. Its half‐life under steady‐state conditions was estimated to be 5.2 days. As a control, tubulin was isolated from the same preparation and its half‐life measured. Under these conditions tubulin exhibited a half‐life of 3.8 days.
REGIONAL γ‐AMINOBUTYRIC ACID LEVELS IN RAT BRAIN DETERMINED AFTER MICROWAVE FIXATION
Authors: Balcom G. J. , Lenox R. H. , Meyerhoff J. L. 
Published: October 2006

Abstract—GABA levels in rat whole brain were compared following three methods of sacrifice: rapid microwave fixation, decapitation into liquid nitrogen, and decapitation at 20°C. Levels were shown to be identical in animals sacrificed by microwave fixation and decapitation into liquid nitrogen. In contrast, rats decapitated at 20°C had 18 per cent higher GABA levels when determined immediately post‐mortem and 48 per cent higher levels after 30 min at 20°C. Microwave treatment prevented these post‐mortem increases. The increase in GABA after decapitation at 20°C was even greater in hypothalamus than in whole brain.A comparison of 3 GABA extraction methods following microwave fixation demonstrated that sodium acetate was 88 per cent as effective as 80 per cent ethanol and more effective than 0·5 n‐perchloric acid in extracting GABA.Fifteen brain regions were dissected from microwave‐treated brains and the GABA levels determined.