bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE [14C]DEOXYGLUCOSE METHOD FOR THE MEASUREMENT OF LOCAL CEREBRAL GLUCOSE UTILIZATION: THEORY, PROCEDURE, AND NORMAL VALUES IN THE CONSCIOUS AND ANESTHETIZED ALBINO RAT1
Authors: Sokoloff L. , Reivich M. , Kennedy C. , Rosiers M. H. Des , Patlak C. S. , Pettigrew K. D. , Sakurada O. , Shinohara M. 
Published: October 2006

Abstract— A method has been developed for the simultaneous measurement of the rates of glucose consumption in the various structural and functional components of the brain in vivo. The method can be applied to most laboratory animals in the conscious state. It is based on the use of 2‐deoxy‐D‐[14C]glucose ([14C]DG) as a tracer for the exchange of glucose between plasma and brain and its phosphorylation by hexokinase in the tissues. [14C]DG is used because the label in its product, [14C]deoxyglucose‐6‐phosphate, is essentially trapped in the tissue over the time course of the measurement. A model has been designed based on the assumptions of a steady state for glucose consumption, a first order equilibration of the free [14C]DG pool in the tissue with the plasma level, and relative rates of phosphorylation of [14C]DG and glucose determined by their relative concentrations in the precursor pools and their respective kinetic constants for the hexokinase reaction. An operational equation based on this model has been derived in terms of determinable variables. A pulse of [14C]DG is administered intravenously and the arterial plasma [14C]DG and glucose concentrations monitored for a preset time between 30 and 45min. At the prescribed time, the head is removed and frozen in liquid N2‐chilled Freon XII, and the brain sectioned for autoradiography. Local tissue concentrations of [14C]DG are determined by quantitative autoradiography. Local cerebral glucose consumption is calculated by the equation on the basis of these measured values.The method has been applied to normal albino rats in the conscious state and under thiopental anesthesia. The results demonstrate that the local rates of glucose consumption in the brain fall into two distinct distributions, one for gray matter and the other for white matter. In the conscious rat the values in the gray matter vary widely from structure to structure (54‐197 μmol/100 g/min) with the highest values in structures related to auditory function, e.g. medial geniculate body, superior olive, inferior colliculus, and auditory cortex. The values in white matter are more uniform (i.e. 33–40 μmo1/100 g/min) at levels approximately one‐fourth to one‐half those of gray matter. Heterogeneous rates of glucose consumption are frequently seen within specific structures, often revealing a pattern of cytoarchitecture. Thiopental anesthesia markedly depresses the rates of glucose utilization throughout the brain, particularly in gray matter, and metabolic rate throughout gray matter becomes more uniform at a lower level.
PURIFICATION AND CHARACTERIZATION OF CARNOSINE SYNTHETASE FROM MOUSE OLFACTORY BULBS
Authors: Horinishi Hiroo , Grillo Mary , Margolis Frank L. 
Published: October 2006

AbstractCarnosine synthetase was purified about 500‐fold from mouse olfactory bulb to a specific activity of approx 25 nmol/min/mg. This is an increase of 800‐fold over that previously reported for this enzyme from rat brain and 11 times higher than the most highly purified enzyme from chicken pectoral muscle. ATP was essential for activity and could not be replaced by ADP. NAD had no effect on the synthesis of carnosine. Of the β‐alanine analogues tested, the purified mouse enzyme incorporated only γ‐aminobutyric acid and β‐amino‐n‐butyric acid into peptide linkage with histidine. Synthesis of carnosine by the mouse olfactory bulb enzyme was competitively inhibited by the histidine analogues, 1‐methyl histidine and 3‐methyl histidine, with Ki values which were at least 40 times the Km value for histidine (16 μM). Ornithine and lysine were more efficient β‐alanine acceptors than 1‐methyl histidine for the mouse enzyme. Enzyme from olfactory epithelium and leg skeletal muscle of mice also showed higher Ki values for 1–methyl histidine than the Km value for histidine. In contrast, carnosine‐anserine synthetase from chicken pectoral muscle gave Km values for histidine, 1‐methyl histidine and 3‐methyl histidine, which were all in the range of 4–12 μM. The differences in substrate specificity between the enzyme from mouse and chicken implies alternate routes of anserine synthesis in these species and predicts the occurrence of certain novel peptides in mouse brain.
ON THE STRUCTURE OF A NEW, FUCOSE CONTAINING GANGLIOSIDE FROM PIG CEREBELLUM
Authors: Sonnino S. , Ghidoni R. , Gall G. , Tettamanti G. 
Published: October 2006

AbstractA new ganglioside, provisionally named GLIVa, was isolated in pure form from pig cerebellum. Ganglioside GLIVa is a disialoganglioside containing fucose. Its basic neutral glycosphingolipid core is the gangliotetraose ceramide: Gal, β 1 → 3 GalNAc, β 1 → 4 Gal, β 1 → 4 Glc, β 1 → Cer.Fucose is α‐glycosidically linked to the 2‐position of external galactose and one N‐acetylneuraminic acid is linked to the other one by an α, 2 → 8 linkage. Thus the total structure of ganglioside GLIVa is the following: Fuc, α 1 → 2 Gal, β 1 → 3 GalNAc, β 1 → 4 (NeuAc, α 2 48 NeuAc, α 2 → 3) Gal, β 1 → 4 Glc, β 1 → Ceramide. According to the IUPAC‐IUB Commission on Biochemical Nomenclature is indicated as II3α(NeuAc)2 IV2αFuc‐GgOse4Cer.
THE EFFECTS OF BOTULINUM TOXIN ON ACETYLCHOLINE METABOLISM IN MOUSE BRAIN SLICES AND SYNAPTOSOMES
Authors: Gundersen Cameron B. , Howard Bruce D. 
Published: October 2006

AbstractThe effects of Type A botulinum toxin on acetylcholine metabolism were studied using mouse brain slice and synaptosome preparations. Brain slices that had been incubated with the toxin for 2h exhibited a decreased release of acetylcholine into high K+ media. Botulinum toxin did not affect acetylcholine efflux from slices in normal K+ media. When labeled choline was present during the release incubation, a‘newly‐synthesized’pool of acetylcholine was formed in the tissue. In toxin‐treated slices exposed to high K+, both the production and the release of this‘newly‐synthesized’acetylcholine were depressed. A possible explanation for these actions of botulinum toxin would be via an inhibition of the high affinity uptake of choline. This hypothesis was tested by measuring the high affinity uptake of [3H]choline into synaptosomes prepared from brain slices. Previous exposure of slices to botulinum toxin caused a significant reduction in the accumulation of label by the synaptosomes. These data are discussed in terms of our current understanding of the mechanism of action of botulinum toxin and the toxin's interaction with the mechanisms regulating acetylcholine turnover.
CEREBRAL METABOLIC CHANGES IN PROFOUND, INSULIN‐INDUCED HYPOGLYCEMIA, AND IN THE RECOVERY PERIOD FOLLOWING GLUCOSE ADMINISTRATION
Authors: Agardh C.‐D. , Folbergrovaa J. , Siesjou B. K. 
Published: October 2006

AbstractSevere hypoglycemia was induced by insulin in lightly anaesthetized (70°o N2O) and artificially ventilated rats. Brain tissue was frozen in situ after spontaneous EEG potentials had disappeared for 5. 10. 15 or 30 min and cerebral cortex concentrations of labile organic phosphates, glycolytic metabolites, ammonia and amino acids were determined. In other experiments, recovery was induced by glucose injection at the end of the period of EEG silence.All animals with an isoelectric EEG showed extensive deterioration of the cerebral energy state. and gross perturbation of amino acid concentrations. The latter included a 4‐fold rise in aspartate concentration and reductions in glutamate and glutamine concentrations to 20 and 5oo of control levels respectively. There was an associated rise in ammonia concentration to about 3μmol‐g‐1.Administration of glucose brought about extensive recovery of cerebral energy metabolism. For example, after an isoelectric period of 30 min tissue concentrations of phosphocreatine returned to or above normal, the accumulation of ADP and AMP was reversed, there was extensive resynthesis of glycogen and glutamine and full normalisation of tissue concentrations of pyruvate. α‐ketoglutarate. GABA and ammonia. However, even after 3 h of recovery there was a reduction in the ATP concentration and thereby in adenine nucleotide pool, moderate elevations of lactate content and the lactate pyruvate ratio, and less than complete restoration of the amino acid pool. It is concluded that some cells may have been irreversibly damaged by the hypoglycemia.
EFFECTS OF THE ANTICONVULSANT SODIUM VALPROATE ON γ‐AMINOBUTYRATE AND ALDEHYDE METABOLISM IN OX BRAIN
Authors: Whittle S. R. , Turner A. J. 
Published: October 2006

Abstract—Succinic semialdehyde dehydrogenase and NADPH‐dependent aldehyde reductase have been purified from ox brain by affinity chromatography on 5′ AMP–Sepharose and 2′5′ ADP–Sepharose respectively. Aldehyde reductase has also been purified using chromatography on Procion Red HE3B–Sepharose. The effects of the anticonvulsant drug sodium valproate were examined on these enzymes, and also on GABA‐aminotransferase partially purified from ox brain. Aldehyde reductase was inhibited by valproate in an uncompetitive manner with respect to aldehyde substrates (Ki= 38–85 μM). The inhibitions of succinic semialdehyde dehydrogenase and GABA aminotransferase were approx 2 orders of magnitude weaker, suggesting that aldehyde reductase may be an important site of action of anticonvulsant drugs.
CEREBRAL BLOOD FLOW AND CEREBRAL METABOLIC RATES FOR OXYGEN, GLUCOSE, AND KETONE BODIES IN NEWBORN DOGS
Authors: Gregoire N. M. , Gjedde A. , Plum F. , Duffy T. E. 
Published: October 2006

Abstract—Cerebral blood flow (CBF) and the cerebral metabolic rates for oxygen, glucose, acetoacetate, β‐hydroxybutyrate and lactate were measured in 1‐ to 5‐day old Beagle dogs under nitrous oxide anesthesia. CBF was determined by 133Xe washout with mechanically integrated blood samples withdrawn simultaneously from a femoral artery and from the posterior one‐third of the superior sagittal sinus. CBF and CMRO2 in normocapnia (PaCO2 40 × 1 mm Hg) were 48 × 5 ml/100 g/min and 2.15 ml/100 g/min, respectively. There was a positive, linear relationship between CBF and PaCO2, calculated for PaCO2 values ranging from 26 to 70 mm Hg. Induced hypocapnia (PaCO2 31 × 1 mm Hg) or hypercapnia (PaCO2 58 × 2 mm Hg) did not alter the CMRO2. Glucose and acetoacetate were taken up by the brain at all PaCO2 levels examined; however, the cerebral uptake of glucose always exceeded the combined uptake of ketone bodies by more than a factor of ten. The cerebral metabolic rate for glucose (94.6 × 3.6 μmol/100 g/min) more than accounted for overall cerebral oxygen consumption, and yielded an oxygen:glucose ratio (mol:mol) of 5.1. Thus, as in adult animals, PaCO2 is an important regulator of cerebral blood flow in puppies, and glucose is the major substrate for oxidative energy production in the immature brain. The oxidation of ketone bodies by the newborn dog brain accounts for not more than 6% of the in vivo cerebral oxygen consumption.
THE LABELLING OF NERVE ENDING PHOSPHOLIPIDS IN GUINEA‐PIG BRAIN IN VIVO AND THE EFFECT OF ELECTRICAL STIMULATION ON PHOSPHATIDYLINOSITOL METABOLISM IN PRELABELLED SYNAPTOSOMES
Authors: Pickard M. R. , Hawtoorne J. N. 
Published: October 2006

Abstract—The intracerebral injection of 32Pi into guinea‐pig cortex resulted in a steady rate of incorporation into all phospholipids over a 20 h period. The specific radioactivities of phosphatidate and phos‐phatidylinositol in synaptosomes prepared from cortex prelabelled, in vivo, were at a maximum after 2 h and the respective activities were 3–8 times higher than in whole cortex. This peak in labelling corresponded with the maximum specific activity of the brain ATP. No similar differential labelling pattern was observed for phosphatidylethanolamine, phosphatidylcholine and phosphatidylserine.Electrical stimulation of the prelabelled synaptosomes produced a rapid drop in the specific activity of phosphatidylinositol and phosphatidate and an increase in the specific activity of CDP‐diacylglycerol. The specific activity of synaptosomal ATP was not affected.Study of the subsynaptosomal fractions obtained after osmotic rupture of the synaptosomes revealed that the most highly labelled phosphatidylinositol was in the synaptic vesicle fraction (D) and the most active phosphatidate was in a ‘microsomal’ fraction (E). Electrical stimulation caused a loss of phosphatidylinositol radioactivity from fraction D and a loss of phosphatidate radioactivity from fraction E. The specific activity of these lipids in other fractions was not affected.A possible role for presynaptic phosphatidylinositol is suggested.
ENTRY OF β‐OXALYL‐l‐α,β‐DIAMINOPROPIONIC ACID, THE LATHYRUS SATIVUS NEUROTOXIN INTO THE CENTRAL NERVOUS SYSTEM OF THE ADULT RAT, CHICK AND THE RHESUS MONKEY
Authors: Rao S. L. N. 
Published: October 2006

Abstract— A comparative study of the tissue disposition of the L. sativus neurotoxin has been done using [3H]0DAP with special reference to the CNS in normal and Diamox treated (acidotic) adult rhesus monkeys and also in the day old chick, a species susceptible to the neurotoxin, and the adult rat which is refractory to it. The neurotoxin was detected in the CNS of the acidotic monkey and also in the normal monkey in nearly the same quantity. The neurotoxin was largely localised in the lumbosacral region of the spinal cord. The amount of radioactive ODAP in the CNS following its intraperitoneal injection was twice that seen following its intravenous injection.The concentrations of the neurotoxin 90 min after injection in the CNS of the adult rat and the day old chick were almost the same and increased 2 fold by 24 h. No radioactive metabolite of ODAP could be detected in either the tissues or the urine of the different species. Species (and age) differences in susceptibility to the L. sativus neurotoxin is thus independent of its entry into the CNS.
STEREOSPECIFIC IN VlTRO BINDING OF [3H]DEXETIMIDE TO BRAIN MUSCARINIC RECEPTORS
Authors: Laduron P. M. , Wimp M. Ver , Leysen J. E. 
Published: October 2006

Abstract—A binding assay for muscarinic cholinergic receptors has been developed using labelled dexetimide as ligand and a filtration technique. The main features of this assay are its stereospecific nature, the very high affinity of the ligand for the specific receptors sitcs and its very low affinity for non‐specific binding sites.The latter point was further investigated using labelled levitimide, the inactive enantiomer. The binding was found to be neither stereospecific nor saturable and displacement by both enantiomers revealed a particular curve with a very flattened course.Kinetic experiments with [3H]dexetimide suggest the occurrence of a heterogenous population of muscarinic receptors in the rat striatum.A study of the regional distribution of muscarinic receptors in rat brain showed a high concentration in the dopaminergic areas, the cortex and the hippocampus, but practically none in the cerebellum.The subcellular distribution pattern revealed a marked enrichment of [3H]dexetimide stereospecific binding sites in the microsomal fraction of rat striatum and hippocampus. Such a distribution was not found with [3H]levitimide. All the characteristics of this binding assay make dexetimide a very appropriate ligand for labelling muscarinic receptors in vitro as well as in vivo.
OXIDIZED AND REDUCED GLUTATHIONE IN THE RAT BRAIN UNDER NORMOXIC AND HYPOXIC CONDITIONS
Authors: Folbergrová Jaroslava , Rehncrona Stig , Siesjö Bo K. 
Published: October 2006

AbstractIn order to test the proposition that hypoxia leads to a change in the concentration ratio of reduced (GSH) and oxidized (GSSG) glutathione in the brain, enzymatic, fluorometric assays were worked out for measuring GSH and GSSG. In lightly anaesthetized and immobilized rats. GSH concentrations in the cerebral cortex and the cerebellum were close to 2 μmol.g‐1 while a slightly lower concentration (approx 1.4μmol.g‐1) was found in the brain stem. In order to avoid artefactual oxidation of GSH during sample preparation for GSSG determination the tissue was extracted with trichloroacetic acid, following alkylation of SH groups with N‐ethylmaleimide. With these precautions GSSG concentrations were approx 0.7% of the corresponding GSH concentrations. However. the results indicated that the true GSSG concentrations may be even lower. During hypoxia there was neither a decrease in GSH nor an increase in GSSG concentrations in cortical tissue or cisternal CSF.
IN VITRO STUDIES ON THE INTERACTION OF BRAIN MONOAMINE OXIDASE WITH 5,6‐ AND 5,7‐DIHYDROXYTRYPTAMINE12
Authors: Klemm H.‐P. , Baumgarten H. G. , Schlossberger H. G. 
Published: October 2006

Abstract[14C]5,6‐Dihydroxytryptamine ([14C] 5,6‐DHT) and [14C]5,7‐dihydroxytryptamine ([14C]5,7‐DHT) were deaminated to toluene‐isoamylalcohol extractable products when incubated with homogenates of rat hypothalamus or pons‐medulla oblongata. [14C]5,6‐Dihydroxyindole acetic acid ([14C]5.6‐DHIAA) and [14C]5,7‐dihydroxyindole acetic acid ([14C]5,7‐DHIAA) were detected as MAO metabolites by TLC besides non‐identified components. The conversion of [14C]5,6‐DHT and [14C]5,7‐DHT obeyed, at least initially, Michaelis‐Menten kinetics (Km 5,7‐DHT: 0.5 × 10−3M; Km 5,6‐DHT: 1.25 × 10−3M). Inhibition of the reaction by the MAO A inhibitor, clorgyline, resulted in a typical double sigmoidal inhibition curve indicating that both amines are metabolized by both types of MAO (A and B). In deprenyl inhibition studies, however, 5,7‐ and 5,6‐DHT seemed to be preferred substrates of MAO A.Incubation of rat brain homogenates with [14C]5,6‐DHT and [14C]5,7‐DHT or with the MAO metabolites [14C]5,6‐DHIAA and [14C]5,7‐DHIAA caused a time‐dependent break‐down of the dihydroxylated indole compounds with subsequent binding of radioactivity to perchloric acid insoluble tissue components.5,6‐DHT inactivated MAO in rat brain homogenates parallel to its decomposition and extensive protein binding. The inactivation of MAO by 5,6‐DHT and the extensive binding of radioactivity to protein were antagonized by dithiothreitol (DTT), glutathione (GSH) and L‐ascorbic acid. Reduction of [O2] in the incubation medium slightly attenuated the inactivation of MAO by 5,6‐DHT. Catalase or superoxide dismutase failed to prevent MAO from being inactivated by 5,6‐DHT. The results suggest that oxidation products of 5,6‐DHT, e.g. its corresponding o‐quinone, are involved in the inactivation of MAO in vitro and mainly responsible for the binding of radioactivity to brain proteins in vitro. Similar mechanisms may also be operative in the in vivo neurotoxicity of 5,6‐DHT.The lack of inactivation of MAO by 5,7‐DHT in vitro correlated with a low degree of radioactivity binding (from [14C]5,7‐DHT) to homogenate protein pellets; the binding to proteins was barely influenced by GSH, cysteine, DTT and l‐ascorbic acid. These latter findings do not provide a plausible explanation for the mechanism(s) involved in the well known in vivo neurotoxicity of 5,7‐DHT.
A RAPID AND SIMPLE METHOD FOR THE DETERMINATION OF PICOGRAM LEVELS OF SEROTONIN IN BRAIN TISSUE USING LIQUID CHROMATOGRAPHY WITH ELECTROCHEMICAL DETECTION
Authors: Ponzio F. , Jonsson G. 
Published: October 2006

AbstractA rapid and simple technique using solvent extraction and high pressure liquid chromatography with electrochemical detection has been developed for the determination of serotonin in small brain tissue samples (1‐20 mg). The method has a reasonably good specificity and a very low experimental error (less than 3%s.e., calculated from six samples processed and analysed from the same brain homogenate). The recovery of authentic 5‐HT added is 80‐90%. The 5‐HT levels of rat whole brain was found with the present technique to be 690 ± 17.5 ng/g and of mouse neocortex 304 ± 16 ng/g. Monoamine oxidase inhibition with pargyline (2 h) increased 5‐HT levels in mouse neocortex to 194 ± 15% (N = 5) of control, while reserpine depleted 5‐HT to 13 ± 4% of control. The method has a sensitivity level of about 20 pg (0.1 pmol) per brain sample.
PURIFICATION OF L‐GLUTAMIC ACID DECARBOXYLASE FROM CATFISH BRAIN
Authors: Thomas Su Y. Y. , Wu J.‐Y. , Lam Dominic M. K. 
Published: October 2006

Abstract—L‐Glutamic acid decarboxylase (GAD) from brain of the channel catfish (Ictalurus punctatus) has been purified to homogeneity by a combination of ammonium sulfate fractionation, gel filtration, calcium phosphate gel and preparative polyacrylamide gel electrophoresis. The purity of the enzyme preparation was established by showing that on both 7.5% regular and 3.7–15% gradient polyacrylamide gel electrophoresis the enzyme migrated as a single protein band which contained all the enzyme activity. The molecular weight of the purified GAD was estimated by gel filtration and gradient polyacrylamide gel to be 84,000 ± 2000 and 90,000 ± 4000, respectively. SDS‐polyacrylamide gel electrophoresis revealed three major proteins with molecular weights of 22,000 ± 2000, 40,000 ± 5000 and 90, 000 ± 6000 which may represent a monomer, dimer, and tetramer. Antibodies against the purified enzyme were obtained from rabbit after four biweekly injections with a total of 80 μg of the enzyme. A double immunodiffusion test using these antibodies and a crude extract from catfish brains showed only a single, sharp precipitin band which still retained the enzyme activity, suggesting that the precipitin band was indeed a GAD‐anti‐GAD complex. In an enzyme inhibition study, a maximum inhibition of 60–70% was obtained at a ratio of GAD protein/anti‐GAD serum of about 1:1.6. Furthermore, the precipitate from the GAD‐anti‐GAD incubation mixture also contained the enzyme activity, suggesting that the antibody was specific to GAD and that the antigen used was homogeneous. Advantages and drawbacks of the purification procedures described here and those used for mouse brain preparations are also discussed.
Association of Newly Synthesized Tubulin with Brain Microsomal Membranes
Authors: Soifer David , Czosnek Henryk 
Published: October 2006

Abstract:Tubulin has been found to be synthesized on both membrane‐bound and free polyribosomes prepared from brain. Cell‐free studies indicate that tubulin made on rough microsomes is incorporated into the endoplasmic reticulum membrane as it is synthesized. This tubulin remains associated with the membrane after sedimentation and washing. The tubulin is not removed from the membrane after stripping ribosomes from the membranes in KCI‐puromycin, followed by repeated washing by either sedimentation or flotation in 0.5 M‐KCI. The membrane tubulin is partially susceptible to proteolysis by trypsin and chymotrypsin: /3‐tubulin is more accessible to the proteases than is a‐tubulin. Nonionic detergents extract mostly /3‐tubulin from the microsomal membrane. Newly synthesized tubulin which has been extracted from microsomal membranes in 0.5% Nonidet P‐40, coassembles and disassembles with carrier microtubule protein. The insertion of newly synthesized tubulin into endoplasmic reticulum membrane may be the first step in the incorporation of tubulin into the plasma membrane.