bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE INFLUENCE OF FUNCTIONAL ALTERATION ON MONOAMINE OXIDASE AND CATECHOL‐O‐METHYL TRANSFERASE IN THE VISUAL PATHWAY OF RATS1
Authors: Bigl V. , Biesold D. , Weisz K. 
Published: October 2006

Abstract—Rats were reared in complete darkness or under chronic stimulation with flashing light from birth to the age of 7 weeks. Light deprivation caused a significant increase in monoamine oxidase activity (measured with [14C]serotonin) of about 30 per cent in the structures of the visual pathway. Chronic stimulation with flashing light had no influence on the activity of monoamine oxidase in either visual or non‐visual structures. The activity of catechol‐O‐methyl transferase in the brain areas of light‐deprived rats was reduced, in light‐stimulated rats it was slightly increased. In mother rats kept together with their litters in either complete darkness or flashing light for 5 weeks no change in monoamine oxidase activity was observed. The activity of catechol‐O‐methyl transferase in mother rats kept in darkness was significantly decreased in all brain regions studied; in light‐stimulated animals the enzyme activity was not affected.
HIGH AFFINITY CHOLINE TRANSPORT IN GUINEA PIG BRAIN AND THE EFFECT OF NOREPINEPHRINE
Authors: Carroll Paul T. , Buterbaugh Gary G. 
Published: October 2006

Abstract—The influence of 1‐norepinephrine on the accumulation of [14C]choline by nuclei‐free homogenates and synaptosomes of guinea‐pig brain was studied. Kinetic analysis of choline accumulation by guinea‐pig brain resulted in both high and low affinity Michaelis constants. Norepinephrine stimulated the high affinity choline transport process but not the low and the magnitude of its stimulation in 3 different brain regions was correlated with the choline acetyltransferase activity of those regions. Depletion of norepinephrine from the brainstem by pretreatment with the catecholamine depleter alpha‐methyl‐para‐tyrosine significantly decreased the maximal velocity of choline transport. Both the alpha adrenergic receptor blocker phentolamine and the beta adrenergic receptor blocker propranalol inhibited norepinephrine induced stimulation of choline transport. Cocaine stimulated choline transport at low concentrations and pretreatment of animals with reserpine significantly antagonized cocaine's stimulation of choline transport. The results suggest that endogenous norepinephrine may modify the high affinity choline transport process in guinea‐pig brain.
CERAMIDE GLYCOSYLTRANSFERASES IN CULTURED RAT CEREBELLUM: CHANGES WITH AGE, WITH DEMYELINATION, AND WITH INHIBITION OF MYELINATION BY 5‐BROMO‐2′‐DEOXYURIDINE OR EXPERIMENTAL ALLERGIC ENCEPHALOMYELITIS SERUM
Authors: Latovitzki N. , Silberberg D. H. 
Published: October 2006

Abstract—UDP‐galactose:ceramide galactosyltransferase (CGalT) (E.C. 2.4.1.62) and UDP‐glucose:ceramide glucosyltransferase (CGlcT) activities were measured in myelinating cultures of newborn rat cerebellum. Specific activities were measured at various days in vitro and the pattern of activities compared with that reported for in vivo tissue. Cultures demyelinated by incubation with media containing 22% serum from rabbits in which experimental allergic encephalomyelitis (EAE) was induced by injection with whole guinea‐pig spinal cord, had 28% of CGalT specific activity and 86% of CGlcT specific activity measured in control cultures. Cultures in which myelination was inhibited by maintenance on media containing 0.15 mm‐5‐bromo‐2′‐deoxyuridine (BUdR) had 10% of CGalT specific activity and 118% of CGlcT specific activity of control cultures. Cultures in which myelination was inhibited by maintenance on media containing 2% EAE serum had 12% of the CGalT specific activity of control cultures. The data suggest that in vitro CGalT is predominantly a glial enzyme while CGlcT occurs primarily in neurons, and that the reduced CGalT activity may be involved in the mechanism of myelination inhibition by BUdR and by EAE serum.
DEOXYRIBONUCLEASES IN DEVELOPING AND ADULT RAT CEREBELLUM: TRANSIENT AND LONG DURATION ACTIONS OF METHYLAZOXYMETHANOL
Authors: Chanda Rita , Woodward D. J. , Griffin W. S. T. 
Published: October 2006

Abstract—Acid and alkaline DNase activities were determined in postnatal and adult rat cerebellum. Normal animals were compared with those injected with 10 mg/kg methylazoxymethanol acetate using varying schedules after birth in order to induce transient damage to proliferating cell populations. In all animals studied, both immature and adult, methylazoxymethanol caused an increase in acidic and decrease in alkaline DNase activity. These effects were not specific to the dividing populations and occurred in nonmitotic cells as well. When injections were given to young adults, these effects appeared irreversible and persisted up to 3 months after birth.
CEREBRAL AROMATIC AMINOTRANSFERASE
Authors: Noguchi T. , Nakatani M. , Minatogawa Y. , Okuno E. , Kido R. 
Published: October 2006

Abstract—Aromatic: 2‐oxoglutarate aminotransferase has been purified about 950‐fold from rat brain mitochondria. The purified enzyme was homogeneous in polyacrylamide gel electrophoresis and had a molecular weight of approx 63,000. On the basis of substrate specificity, substrate inhibition, purification ratio, yield, polyacrylamide gel electrophoresis and some other properties of the enzyme it has been suggested that brain mitochondrial tyrosine:2‐oxoglutarate aminotransferase (l‐tyrosine: 2‐oxoglutarate aminotransferase, EC 2.6.1.5) is identical with brain mitochondrial phenylalanine and kynurenine: 2‐oxoglutarate aminotransferases (l‐kynurenine: 2‐oxoglutarate aminotransferase, EC 2.6.1.7), and also with aspartate: 2‐oxoglutarate aminotransferase (l‐aspartate: 2‐oxoglutarate aminotransferase, EC 2.6.1.1).
IN VIVO STUDIES ON THE METABOLISM OF [15,16‐3H]TETRACOSANOIC ACID (LIGNOCERIC ACID) IN ADULT RAT BRAIN
Authors: Seidel D. , Nowoczek G. , Jatzkewitz H. 
Published: October 2006

Abstract—Adult rats were killed 16 h, 48 h, 6 days and 21 days after intracerebral application of n‐[15,16‐3H]tetracosanoic acid (lignoceric acid). After incorporation into complex lipids with a strong preference for the ester‐bound fatty acids of glycerophospholipids, radioactivity decreased with time. The incorporated activity into the amide‐bound fatty acids of sphingolipids was also shown to decrease, with exception of the cerebroside of the hydroxy fatty acid type (cerebron fraction). Only negligible amounts of labelled triglyceride and cholesterol ester could be detected.The fatty acids derived from the complex lipids were analysed by radio gas chromatography. It was revealed that some of the applied labelled lignoceric acid was hydroxylated and incorporated into the cerebron fraction while the rest had their chains shortened. In the latter case all even and odd numbered chain lengths down to C18 and C16 (stearic and palmitic acid) were detected. At this stage, the pool of the degradation products of lignoceric acid is stabilized by the preferred incorporation of fatty acids of these chain lengths into glycerophospholipids. A time‐dependent desaturation to oleic acid from stearic acid was observed.
INHIBITION OF GABA UPTAKE IN RAT BRAIN SLICES BY NIPECOTIC ACID, VARIOUS ISOXAZOLES AND RELATED COMPOUNDS
Authors: Krogsgaard‐Larsen P. , Johnston G. A. R. 
Published: October 2006

Abstract—A variety of isoxazoles structurally related to muscimol (3‐hydroxy‐5‐aminomethylisoxazole) were tested as inhibitors of the uptake of GABA and some other amino acids in rat brain slices, and of the activity of the GABA‐metabolizing enzymes l‐glutamate 1‐carboxylyase and GABA:2‐oxo‐glutarate aminotransferase. A bicyclic derivative, 4,5,6,7‐tetrahydroisoxazolo[4,5‐c]pyridin‐3‐ol, proved to be a more potent inhibitor of GABA uptake than muscimol. Structure‐activity studies on this derivative, which appeared to be a competitive inhibitor of GABA uptake, led to the findings that nipecotic acid (piperidine‐3‐carboxylic acid) is a powerful non‐competitive inhibitor of GABA uptake, and that perhydro‐1,2‐oxazine‐6‐carboxylic acid is a relatively weak competitive inhibitor of GABA uptake.
BOVINE ADRENAL MEDULLARY DOPAMINE‐β‐HYDROXYLASE: STUDIES ON INTERACTION WITH CONCANAVALIN A
Authors: Aunis D. , Miras‐portugal M. T. , Mandel P. 
Published: October 2006

Abstract—Bovine adrenal medullary dopamine‐β‐hydroxylase binds with concanavalin A and forms an enzymically active precipitate. The formation of the insoluble complex is pH‐dependent and can be inhibited by α‐methyl‐D‐mannoside, D‐mannose and D‐glucose. The insoluble complex can be dissociated into two species with α‐methyl‐D‐mannoside. From the results, it appears that the interaction between dopamine‐β‐hydroxylase and concanavalin A is due to the carbohydrate moiety of dopamine‐β‐hydroxylase. This property was used to purify the enzyme from a soluble lysate of chromaffin granules. Of all the proteins contained in the soluble lysate, dopamine‐β‐hydroxylase was the only one to be retained on a column of concanavalin A covalently bound to Sepharose 4B. The preparation of pure dopamine‐β‐hydroxylase exhibits a very high specific activity of 320 μmol of octopamine formed per 30 min per mg of protein.
LACK OF PHOSPHOLIPID TRANSPORT MECHANISMS IN CELL MEMBRANES OF THE CNS1
Authors: Pasquini J. M. , Gomez C. J. , Najle R. , Soto E. F. 
Published: October 2006

Abstract—The possible transport role of phospholipid‐protein complexes, present in the cell supernatant of rat brain was investigated using labelled choline as precursor of phosphatidyl choline.Results obtained after the intracranial injection of choline gave no indication of a sequence of events compatible with a transport of phospholipid molecules from the possible site of synthesis (microsomes) to the supernatant and subsequently to myelin.Chase experiments using rat brain slices incubated in vitro with radioactive choline agreed well with the above mentioned results. Contrariwise, when Na352SO4 was used as precursor, the results clearly indicated that synthesis of sulphatides takes place in microsomes, followed by transfer of the radioactive lipid to sulphatide‐containing lipoproteins in the supernatant and finally to myelin.Results presented in this paper seem to give further support to the idea that other subcellular fractions, besides microsomes, can autonomously synthesize part of their own provision of phospholipids.Possible reasons which might explain the marked differences between the mechanisms of addition of phospholipids and sulphatides to myelin are discussed in relation to results obtained by other investigators.
CYCLIC ADENOSINE 3′, 5′‐MONOPHOSPHATE IN GUINEA PIG CEREBRAL CORTICAL SLICES: POSSIBLE REGULATION OF PHOSPHODIESTERASE ACTIVITY BY CYCLIC ADENOSINE 3′, 5′‐MONOPHOSPHATE AND CALCIUM IONS
Authors: Schultz J. 
Published: October 2006

Abstract—Cyclic adenosine 3′, 5′‐monophosphate (cyclic AMP) accumulates in guinea pig cerebral cortical slices during incubation with histamine, histamine + noradrenaline and adenosine. Noradrenaline does not enhance cyclic AMP formation. In the absence of Ca2+ ions and presence of 1 mM‐EGTA in the Krebs‐Ringer bicarbonate medium the effects of histamine, histamine + noradrenaline and adenosine are significantly enhanced and noradrenaline elicits an increase in cyclic AMP over control levels. When histamine is used as stimulant, cyclic AMP levels start to decline after only 5 min. However, in the absence of calcium and in the presence of EGTA in the medium this decline is not observed and cyclic AMP levels continue to rise for a considerable period of time. In normal medium, responses to restimulation by histamine or histamine + noradrenaline are greatly reduced in magnitude after a prior stimulation by these putative neurotransmitters. In contrast, when calcium is omitted from the incubation medium and 1 mM‐EGTA is included, cyclic AMP levels increase to normal values at a second stimulation with histamine or histamine + noradrenaline. When slices are preincubated for various periods of time with histamine before addition of noradrenaline, the accumulation of cyclic AMP is significantly reduced as compared to levels obtained when histamine + noradrenaline were added simultanously. This decline in the overall response to histamine + noradrenaline is not observed when preincubation with histamine and subsequent incubations with histamine + noradrenaline are performed in Ca2+‐free, 1 mM‐EGTA containing buffer. Also preincubation with noradrenaline in normal, calcium‐containing medium does not affect the total amount of cyclic AMP accumulating in the brain slices.The results are discussed in terms of an activation of phosphodiesterase within the cerebral cortical slices by increased levels of intracellular, freely available calcium which is mediated by the elevation of cyclic AMP concentration following hormonal stimulation.
PROTEIN KINASES IN MYELIN OF RAT BRAIN: SOLUBILIZATION AND CHARACTERIZATION
Authors: Miyamoto E. 
Published: October 2006

Abstract—Myclin from rat brain contained adenosine 3′, 5′‐monophosphate (cyclic AMP)‐dependent protein kinase activity, which was solubilized by 0.2% Triton X‐100 and required exogenous protein substrate for its activity. Also present was a protein kinase which catalysed the phosphorylation of the endogenous substrate and which was neither solubilized by Triton X‐100 nor stimulated by cyclic AMP. Sodium fluoride was required to maintain the activity of the endogenous phosphorylation, probably by inhibiting ATPase activity, but had no effect on the phosphorylation of histone by the solubilized enzyme. Protamine and myelin basic protein served as well as histone as a substrate for the solubilized enzyme. A protein kinase modulator had no effect on the endogenous phosphorylation, but inhibited histone phosphorylation by the solubilized enzyme. Cyclic AMP‐binding activity was observed in both the solubilized and non‐solubilized preparations. The concentration of cyclic AMP required to give half‐maximal binding activity of the preparations was about 2.5 nM.The results indicate that the cyclic AMP‐binding site of the protein kinase in myelin may partially be accessible, whereas the catalytic site may be integrated into the membrane structure of myelin.
TETRODOTOXIN BINDING AS A MARKER FOR FUNCTIONAL DIFFERENTIATION OF VARIOUS BRAIN REGIONS DURING CHICK AND MOUSE DEVELOPMENT
Authors: Unsworth R. , Hafemann D. R. 
Published: October 2006

Abstract—Measurements of wet wt. and tetrodotoxin (TTX) binding have been made for various regions of chicken and mouse brain during development. The results in each case describe a sigmoid curve.In the chick all brain regions (telencephalon, optic tecta, cerebellum and brainstem) bind significant levels of TTX at hatching, but the brainstem is already at the adult level of binding.In the mouse only the brainstem binds measureable amounts of TTX at birth, indicating that it is the only brain region capable of generating sodium spikes in the newborn animal. Tetrodotoxin binding does not appear in the mouse cerebellum until after the first postnatal week, but subsequent to this time the development of TTX binding is more rapid in this structure than in any other.
FUNCTIONAL HOMOGENEITY OF LEUCINE POOL IN RETINA CELLS1
Authors: Ames A. , Parks J. M. 
Published: October 2006

Abstract—Data on leucine metabolism in isolated rabbit retina are examined for evidence, for or against, a common intracellular pool of free leucine. Data include values for: concentrations, transport rates, degradative metabolism and protein incorporation of labelled leucine measured over a wide range of concentrations; protein incorporation of labelled threonine, measured simultaneously; and an indirect measurement of protein breakdown. The fall in labelled leucine incorporation into protein, when medium leucine was reduced below 100 μM, corresponded closely with the fall in intracellular specific activity predicted from rate of influx of labelled leucine from medium and rate of release of unlabelled leucine from protein breakdown. Protein incorporation of labelled leucine competed with decarboxylation and outward transport and reduced the free intracellular leucine in about the amounts predicted for a common pool. Implications for measurements using labelled amino acid are discussed.
PHOSPHOLIPID COMPOSITION AND [14C]GLYCEROL INCORPORATION INTO GLYCEROLIPIDS OF TOAD RETINA AND BRAIN
Authors: de Bazán Haydée E. Pascual , Bazán N. G. 
Published: October 2006

Abstract—The phospholipid composition as well as the in vivo [14C]glycerol uptake in lipids was found to be similar in the toad brain and retina. The choroid lipid labeling was markedly different. An in vitro time‐course study of [14C]glycerol incorporation in toad retina lipids disclosed that under the conditions of these experiments: (1) retina is able to rapidly synthetize phosphatidic acid from the radioactive precursor; (2) the sequence phosphatidic acid‐diacylglycerol‐triacylglycerol operates; (3) a high rate of phosphatidylinositol de novo biosynthesis takes place; (4) phosphoglycerides of choline and of ethanolamine are also heavily labeled after a lag period; (5) in vivo labeling profiles resembled those obtained in vitro mainly regarding phosphatidylinositol biosynthesis; and (6) the presence of glycerol kinase in the CNS is suggested.
A LYMPH NODE NEUTRAL PROTEINASE ACTING ON MYELIN BASIC PROTEIN
Authors: Smith Marion Edmonds 
Published: October 2006

Abstract—A neutral protease present in inguinal and popliteal lymph nodes of rats with acute experimental allergic encephalomyelitis (EAE), rats injected with Freund's adjuvant, and rats that are normal has been found to hydrolyze basic protein present in purified brain and spinal cord myelin. The enzyme has been enriched by ammonium sulfate precipitation, and its properties have been studied. The protease activity toward different substrates was very specific and decreased in the following order: Protamine sulfate = polylysine (MW 183,000) > myelin basic protein > histone > polylysine (MW 2000) > polyarginine > cytochrome c. Other proteins including casein, freshly denatured hemoglobin, egg albumin, bovine serum albumin, and ribonuclease were ineffective as substrates. The pH curve showed a peak at pH 7 for rat myelin, isolated beef basic protein, and histone. A possible role for this enzyme in demyelination in acute experimental allergic encephalomyelitis is suggested.
PURIFICATION, CHARACTERIZATION AND IDENTIFICATION OF TRYPTOPHAN AMINOTRANSFERASE FROM RAT BRAIN
Authors: Minatogawa Y. , Noguchi T. , Kido R. 
Published: October 2006

Abstract—Tryptophan aminotransferase was purified from rat brain extracts. The purified enzyme had an isoelectric point at pH 6.2 and a pH optimum near 8.0. On electrophoresis the enzyme migrated to the anode. The enzyme was active with oxaloacetate or 2‐oxoglutarate as amino acceptor but not with pyruvate, and utilized various L‐amino acids as amino donors. With 2‐oxoglutarate. the order of effectiveness of the L‐amino acids was aspartate 〉 5‐hydroxytryptophan > tryptophan > tyrosine > phenylalanine. Aminotransferase activity of the enzyme towards tryptophan was inhibited by L‐glutamate. Sucrose density gradient centrifugation gave a molecular weight of approx. 55,000. The enzyme was present in both the cytosol and synaptosomal cytosol, but not in the mitochondria. The isoelectrk focusing profile of tryptophan: oxaloacetate aminotransferase activity was identical with that of L‐aspartate: 2‐oxoglutarate aminotransferase (EC 2.6.1.1) activity, with both subcellular fractions.On the basis of these data, it is suggested that the enzyme is identical with the cytosol aspartate: 2‐oxoglutarate aminotransferase.
CYSTEINE SULPHINATE DECARBOXYLASE IN CHICK AND RAT RETINA DURING DEVELOPMENT
Authors: Pasantes‐Morales H. , Lopez‐Colome A. M. , Salceda R. , Mandel P. 
Published: October 2006

Abstract—The activity, properties and developmental pattern of cysteine sulphinate decarboxylase (CSD) were studied in chick and rat retina Retinal CSD shows properties similar to those of the enzyme in brain with respect to optimum pH, saturating substrate concentrations and stimulation by pyridoxal phosphate. CSD activity increased 3‐fold from the 10th day of embryogenesis to hatching in chicks and in postnatal development in rats. The developmental pattern of CSD activity in both species is coincident with the functional maturation of visual function.
DETECTION OF MYELIN IN THE OPTIC NERVE OF YOUNG RATS BY SEDIMENTATION EQUILIBRIUM IN A CsCl GRADIENT1
Authors: Detering Nancy K. , Wells M. A. 
Published: October 2006

Abstract—A method is described for detecting myelin in small amounts of tissue by density criteria. Samples are homogenized in 0.926 m‐CsCl, 10 mm‐Tris‐HCl, (pH 7.4), 5 mm‐Ca2+ solution and centrifuged to equilibrium at 52,000 rev./min and 4°C in the AN‐F rotor of the Model E analytical ultracentrifuge. Homogenates of white matter show a band of material in the density range of 1.20–1.130 g/ml, whereas gray matter homogenates do not show a band of material in this density region. A preparative method is described for isolating the material banding in the region of 1.120–1.130 g/ml from optic nerve homogenates of 21‐day old rats. This material has (1) a protein content of 22–24%, (2) an enzymatic activity for 2′,3′‐cyclic nucleotide phosphohydrolase of 13.1 μmol/min per mg protein and (3) a phospholipid‐cholesterol‐galactolipid molar ratio of 100:100:48. Plasmalogen accounted for 22% of the phospholipid, and sulfatide accounted for 31% of the galactolipid. This material is 85% soluble in chloroform:methanol (2:1. v:v). Developmental studies indicate that this myelin material can first be detected in the optic nerve from an 11‐day‐old rat.
PHOSPHOLIPID METABOLISM IN SUBACUTE SCLEROSING PANENCEPHALITIS : ACTIVITY OF BRAIN PHOSPHOLIPASE A2 TOWARDS SPECIFICALLY LABELLED 1,2‐DIACYL‐, 1‐ALK‐1′‐ENYL‐2‐ACYL‐ AND 1‐ALKYL‐2‐ACYL‐sn‐GLYCERO‐3‐PHOSPHORYLCHOLINE
Authors: Woelk H. , Jakumeit‐Morgott U. , Schenck K. 
Published: October 2006

Abstract—1,2‐Diacyl‐, 1‐alk‐1′‐eny1‐2‐acyl‐ and 1‐alky1‐2‐acyl‐sn‐glycero‐3‐phosphorylcholine specifically labelled with different fatty acids at the 2 position, were prepared enzymically using the acyltransferase system of rabbit sarcoplasmic reticulum. The substrates were submitted to hydrolysis by phospholipase A2 (phospholipid acyl‐hydrolase, EC 3.1.1.4) obtained from normal and brain tissue affected with subacute sclerosing panencephalitis. In the diseased tissue an increase of phospholipase A2 activity ranging from 46 to 54% could be observed in comparison to the control brain for all substrates investigated. Among the investigated substrates phospholipase A2 had the highest affinity for the 1,2‐diacylcompound, whereas alkenylacyl‐ and alkylacyl‐sn‐glycero‐3‐phosphorylcholine were cleaved at almost similar rates. The hydrolysis rate of choline‐plasmalogen and the corresponding diacyl compound by the enzyme was greatly influenced by the fatty acid moiety located at the 2 position of the substrates.
THE INCORPORATION OF [1‐14C]ACETATE INTO UNESTERIFIED FATTY ACIDS IN RAT CEREBRAL CORTEX IN VIVO
Authors: Bonser R. W. , Lunt G. G. 
Published: October 2006

Abstract—The incorporation of [1‐14C]acetate into unesterified fatty acids and into the fatty acids of neutral glycerides and of phospholipids has been measured in rat cerebral cortex in vivo. The most rapid incorporation is seen in the unesterified fatty acids which have a turnover time of 5‐6 min. It is suggested that unesterified fatty acids are precursors to neutral glycerides and phospholipids rather than being derived from them by lipase activity.