bluuebunny/crossref_metadata_2025 huggingface dataset:
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

—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

—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.
THE BINDING OF 5‐HYDROXYTRYPTAMINE TO BUTANOL EXTRACTS OF RAT BRAIN STEM
Authors: Godwin S. F. R. , Sneddon J. M.
Published: October 2006

Abstract— When butanol‐water extracts of rat brain stem were incubated with [3H]5‐HT, (5 × 10−7m), and the components resolved by chromatography on LH20 Sephadex, a peak representing approximately 70% of the eluted radioactivity was found in chloroform‐methanol 4:1. The peak was not found in identically prepared extracts from rat diaphragm, neither was a similar peak found when brain extracts were incubated with [14C]ACh (10−6m), suggesting a degree of selectivity. Binding was not saturated at concentrations of 5 × 10−5m‐5‐HT. The binding was highly sensitive to the presence of water, requiring about 15% (v/v) for optimum binding. The implications of these findings are discussed in terms of a possible ‘5‐HT receptor’.
EFFECTS OF DEXAMETHASONE ON PHENYLETHANOLAMINE N‐METHYLTRANSFERASE AND ADRENALINE IN THE BRAINS AND SUPERIOR CERVICAL GANGLIA OF ADULT AND NEONATAL RATS
Authors: Moore K. E. , Phillipson O. T.
Published: October 2006

Abstract— Phenylethanolamine N‐methyltransferase (PNMT) activity assayed by a sensitive radiochemical method was found to be distributed unevenly in the adult rat brain. Highest activities of this enzyme were located in the medulla and the hypothalamus. Small amounts of adrenaline were identified in the hypothalamus using a sensitive enzymatic radiochemical assay procedure, whereas in the medulla and other brain regions the values for adrenaline were at the limits of the sensitivity of the assay for this amine. The daily administration of dexamethasone (1 mg/kg) to adult rats for 13 days significantly increased PNMT activity in medulla and hypothalamus and also increased the adrenaline content of the hypothalamus. Five daily injections of dexamethasone (0·1 mg/kg) to newborn rats did not alter the PNMT activity or the catecholamine content of the brain, but markedly increased the PNMT activity and adrenaline content of superior cervical ganglia. Higher doses of dexamethasone given to newborn rats (6 daily injections of 1 mg/kg) increased PNMT activity both in the medulla and in the hypothalamus.
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.
SYNTHESIS AND RELEASE OF PROSTAGLANDINS BY RAT BRAIN SYNAPTOSOMAL FRACTIONS1
Authors: Raffel G. , Clarenbach P. , Peskar B. A. , Hertting G.
Published: October 2006

Abstract— Particulate fractions from rat brain homogenate containing the synaptosomes synthesize and release prostaglandins F and E on aerobic incubation. The prostaglandin of the F‐typc released could be further identified as proslaglandin F2α using specific radioimmunoassays for prostaglandins F1α, and F2α‐. The metabolite 13,14‐dihydro‐15‐keto‐prostaglandin F2α could not be detected. The amount of prostaglandins released is dependent on incubation time and temperature as well as pH and osmolarity of the incubation medium. Total brain homogenate released more prostaglandins than purified synaptosomes per mg protein, indicating that synaptosomes are probably not a main source of prostaglandins when compared with other subcellular brain fractions. While prostaglandin synthesis was only moderately increased by the addition of the precursor fatty acid arachidonic acid, anti‐inflammatory drugs like indomethacin, high concentrations of some local anaesthetics and Δ1‐tetrahydrocannabinol inhibited prostaglandin release. The neurotransmitters noradrenaline, dopamine and 5‐hydroxytryptamine did not influence prostaglandin release from the synaptosomal rat brain fractions.
CHLOROTETRACYCLINE‐ASSOCIATED FLUORESCENCE CHANGES DURING CALCIUM UPTAKE AND RELEASE BY RAT BRAIN SYNAPTOSOMES1
Authors: Schaffer Walter T. , Olson Merle S.
Published: October 2006

Abstract– The fluorescent divalent metal chelate‐probe, chlorotetracycline (CTC), was used as a dynamic monitor of calcium association with rat brain snynaptosomes. The determined fluorescence excitation and emission maxima, 412 nm and 522 nm respectively, were used to monitor membrane‐calcium interactions as a function of various parameters. Positive correlations were observed between increased or decreased fluorescence quantum yield and the uptake of both CTC and 45Ca by synpatosomes. The divalent metal ionophore A23187 enhanced fluorescence as well as probe and 45Ca uptake. Whereas, the polar chelator, EGTA, markedly reduced fluorescence, and the synaptosomal bound CTC and 45Ca. The CTC fluorescence changes also demonstrated the saturable manner in which 45Ca bound synaptosomes. At concentrations greater than 100μg/ml, CTC bound to the synaptosomes in a manner which quenched fluorescence at 522 nm. Also, CTC, at concentrations above 15 μg/ml, enhanced the uptake of 45Ca. At CTC concentrations between 10 and 15 μg/ml the quenching and iono‐phoretic properties of the probe were minimized without affecting the capability of using the probe to visualize calcium interactions with synaptosomal membranes. Also, at a low CTC concentration (12.5 μg/ml) the inhibition of calcium uptake by increasing monovalent ion concentrations was clearly demonstrated.
CYCLIC NUCLEOTIDES IN MURINE BRAIN: EFFECT OF HYPOTHERMIA ON ADENOSINE 3′,5’ MONOPHOSPHATE, GLYCOGEN PHOSPHORYLASE, GLYCOGEN SYNTHASE AND METABOLITES FOLLOWING MAXIMAL ELECTROSHOCK OR DECAPITATION
Authors: Lust W. D. , Passonneau J. V.
Published: October 2006

Abstract—The accumulation of adenosine‐3′,5′‐cyclic monophosphate (cyclic AMP) has been investigated in murine brain following electroconvulsive shock and decapitation. Animals were made hypothermic (20°C) to minimize the freezing time of the brain and to delay metabolic events. Cyclic AMP concentrations were decreased in the cerebral cortex of hypothermic rats and mice. Furthermore, the changes in cyclic AMP elicited by electroconvulsive shock and decapitation were delayed. In hypothermic animals, the metabolic rate as determined by high energy phosphate use was decreased to 65% of control values. The interconversions of the active and inactive forms of glycogen phosphorylase and glycogen synthase were sufficiently retarded in hypothermic animals to correlate with changes in cyclic AMP concentrations. The conversion of phosphorylase b to a and synthase a to b occurred when cyclic AMP concentrations had increased from 2 to 5 μmol/kg, following either electroconvulsive shock or decapitation. The results indicate that cyclic AMP plays a role in regulation of glycogen metabolism in cerebral cortex.
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

—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

—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

—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.
EFFECTS OF ELECTROCONVULSIVE SHOCK AND CYCLOHEXIMIDE ON THE INCORPORATION OF AMINO ACIDS INTO PROTEINS OF MOUSE BRAIN SUBCELLULAR FRACTIONS1
Authors: Dunn A. J. , Bergert B. J.
Published: October 2006

—The incorporation of [4,5‐3H]lysine and [1‐14C]leucine into the proteins of subcellular fractions of mouse brain was examined following a single electroconvulsive shock (ECS) or following cycloheximide injections. When the [3H]lysine was injected intraperitoneally immediately after the ECS the incorporation into total brain proteins was decreased by more than 50% as compared to sham controls. The proportion of lysine incorporated into the microsomal fraction was increased, but no changes were observed in the other subcellular fractions including the synaptosomal fraction. With extended pulses administered at various times after the ECS there was no change in total incorporation nor were selective effects seen in any subcellular fractions. With intracranial injections of both [3H]lysine and [14C]leucine the decreased incorporation caused by ECS was not observed, neither were there selective changes in any subcellular fraction. This lack of inhibition occurred because the intracranial injection itself severely inhibited [3H]lysine incorporation. Cycloheximide (30 mg/kg) which depressed [3H]lysine incorporation into brain proteins by 84% caused a selective depression of the incorporation into the cell‐sap fraction and selective elevations into the microsomal and synaptosomal fractions. Similar changes were seen with a higher (amnestic) dose of cycloheximide (150 mg/kg) which inhibited incorporation by 94%. These data are interpreted in terms of the diverse mechanisms by which ECS and cycloheximide inhibit protein synthesis.
EFFECT OF EXOGENOUS LIPIDS ON ACTIVITIES OF THE RAT BRAIN CHOLESTEROL ESTER HYDROLASE LOCALIZED IN THE MYELIN SHEATH1
Authors: Igarashi M. , Suzuki K.
Published: October 2006

Abstract— Activity of cholesterol ester hydrolase localized almost exclusively in the myelin sheath (Eto & Suzuki, 1973a) was greatly affected by exogenous lipids added to the assay mixture. With isolated myelin as the enzyme source, phosphatidylserine was most effective in stimulating the activity. Other phospholipids were less effective. Efhanolamine phospholipid was slightly inhibitory and lysolecithin was strongly inhibitory. Differences in the fatty acid composition did not appear to account for such different effects. Glucosylceramide, galactosylceramide and digalactosylceramide were stimulatory while sulfatide, ganglioside and its asialo‐derivative were inhibitory. Saturated fatty acids were generally stimulatory while corresponding unsaturated acids were strongly inhibitory. In order for exogenous lipids to be effective they had to be added to the assay mixture as free dispersion. When heat‐inactivated myelin was used as the lipid source, no effect was observed, while equivalent amounts of a whole white matter lipid mixture was effective. Although phosphatidylserine was the most effective activator among the lipids tested, it could not completely replace sodium taurocholate present in the standard assay system. When isolated myelin was stored frozen, the activity of the enzyme declined gradually in the standard system without additional lipids. The stimulating effect of phosphatidylserine was greater for such partially inactivated enzyme sources, although it did not completely restore the activity to that of fresh preparations. When myelin was fractionated into basic protein, proteolipid protein and the high molecular weight acidic protein (Wolfgram) fractions, the last fraction contained most of the recovered activity. However, Wolfgram protein was less active than the intact myelin when assayed without additional lipid. The addition of phosphatidylserine completely restored the activity of this partially delipidated preparation.
ISOLATION OF HYDROPHOBIC PROTEINS BINDING AMINO ACIDS: l‐ASPARTIC ACID‐BINDING PROTEIN FROM THE RAT CEREBRAL CORTEX
Authors: Fiszer de Plazas Sara , De Robertis E.
Published: October 2006

Abstract— Lyophilized rat cerebral cortex was treated with chloroform‐methanol (2:1, v/v), and the extracted hydrophobic proteins (i.e. proteolipids) were separated by column chromatography on Sephadex LH‐20. The first peak of protein, eluting with chloroform in the void volume, had high affinity binding for l‐[14C]aspartic acid. The saturation of the binding showed three saturable sites with apparent dissociation constants of 0.2 μm, 10 μm and 50 μm. The binding capacities of the three sites were 2.8, 132 and 617 nmol/mg of protein, respectively. There were 8.0 nmol of high affinity binding sites for l‐aspartic acid and 1.53 nmol for l‐glutamic acid per g of fresh tissue in the cerebral cortex of the rat. Differentiation between binding of l‐aspartic and l‐glutamic acid was clearly established by cross‐binding and competition experiments with agonists and antagonists.

It is suggested that the isolated protein fraction may correspond to a synaptic receptor and not to the transport system. It is concluded that in the cerebral cortex there is a separate receptor for l‐aspartic acid. This is further support to the possible role of this amino acid as a central excitatory transmitter.
SUBCELLULAR LOCALIZATION OF TRYPTOPHAN‐5‐MONO‐OXYGENASE IN BOVINE PINEAL GLANDS AND RAPHE NUCLEI
Authors: Hori S. , Kuroda Y. , Saito K. , Ohotani S.
Published: October 2006

Abstract— Tryptophan‐5‐mono‐oxygenase from both bovine raphe nuclei and pineal glands was activated by preincubation with dithiothreitol and ferrous ion at pH 8.5. The optimum pH for the enzyme activity lies between pH 6.4 and 7.3. Preincubation increased the activity of the enzyme from raphe nuclei by about 20 times in both the homogenate and 105,000 g precipitate prepared from it. Activity in the 105,000 g supernatant fraction was about trebled. Corresponding increases in pineal gland enzyme activity were noted: 100 times in homogenate and 105,000 g precipitate and 15 times in 105,000 g supernatant fluid. Total recoveries of activated enzyme from the homogenate prepared in hypo‐osmotic medium, in the 105,000 g supernatant and precipitate, were 87.1% and 79.0% for raphe nuclei and pineal glands respectively. Of this, 89.5‐91.3% in the case of the raphe nuclei and 76.0‐82.0% in the case of the pineal glands, was found in the precipitate. In contrast, 85‐90% of the lactate dehydrogenase activity was found in the supernatant fraction. The results of subcellular fractionation revealed that the raphe nuclear enzyme was located in both ‘mitochondrial’ and ‘microsomal’ fraction while the pineal gland enzyme was effectively restricted to the ‘mitochondrial’ fraction. The structural characteristics of the fraction were confirmed by electron microscopy.
INHIBITION OF RAT BRAIN PHENOL SULPHOTRANSFERASE IN VITRO BY NORADRENALINE and DOPAMINE METABOLITES1
Authors: Pennings E. J. M. , Vrielink R. , Wolters W. L. , Van Kempen G. M. J.
Published: October 2006

Abstract— Kinetic parameters of the sulphotransferase reaction in rat brain were investigated in vitro at pH 7.4. Evidence is presented that the enzyme phenol sulphotransferase (EC 2.8.2.1) can be assayed with 4‐methylumbelliferone or 3‐methoxy‐4‐hydroxyphenylethyleneglycol as the substrate. Both assays give identical Vmax values, whereas Km values are 0.026 mm and 0.039 mm, respectively. Normetanephrine, metanephrine and the catecholamines adrenaline and dopamine, having a positive charge on the side chain at pH 7.4, do not inhibit 4‐methylumbelliferone and 3‐methoxy‐4‐hydroxyphenylethy‐leneglycol sulphotransferase at this pH. Their deaminated metabolites 3,4‐dihydroxyphenylethyleneglycol, 3,4‐dihydroxymandelic acid, 3,4‐dihydroxyphenylacetic acid, 3‐methoxy‐4‐hydroxyphenylethylene glycol, 3‐methoxy‐4‐hydroxyphenethanol and 3‐methoxy‐4‐hydroxyphenylacetic acid inhibit both the enzyme activities. The type of inhibition is noncompetitive with the exception of 3‐methoxy‐4‐hydroxy‐phenylethyleneglycol, which is a competitive inhibitor of 4‐methylumbelliferone sulphation. 3‐Methoxy‐4‐hydroxy‐mandelic acid does not inhibit the enzyme activities. It is concluded that the catecholamines themselves are not sulphated by rat brain in vitro at pH 7.4.
RAPIDLY LABELLING AND EXPORTED NEURONAL PROTEIN; [3H]FUCOSE AS A PRECURSOR, AND EFFECTS OF CYCLOHEXIMIDE AND COLCHICINE
Authors: Rose S. P. R. , Sinha A. K.
Published: October 2006

Abstract— The characteristics of a rapidly labelled and rapidly transported neuronal perikaryal protein fraction (Rose & Sinha. 1974a) were investigated in three experiments. (1) The kinetics of labelling of neuronal cell body and neuropil fractions from [3H]fucose were followed and shown to be similar to those from [3H]lysine, the label first appearing in the neuronal fraction and then being exported. The neuronal/neuropil incorporation ratio fell from 1.37 at 1 h to 0.77 at 4 h. (2) When cycloheximide (5 mg/kg) was injected intraperitoneally 15 min after [3H]lysine, incorporation into neuronal protein was inhibited to a greater extent (85%) than into neuropil (60%). (3) Colchicine was injected at a dose (40 μg/kg) sufficient to prevent accumulation of radioactively labelled protein into synaptosomes but insufficient to affect total incorporation of precursor into protein. [3H]Lysine was injected 1 h after colchicine and neurons and neuropil fractions made 1 h and 4 h later; colchicine inhibited the export of labelled protein from the neuronal perikaryon and its accumulation in the neuropil. We conclude that the rapidly labelled neuronal protein is partially glycoprotein in character and may be normally transported from the cell body by way of the axonal/(dendritic?) flow mechanism.
SODIUM AND CHLORIDE FLUXES IN SYNAPTOSOMES IN VITRO
Authors: Marchbanks R. M. , Campbell C. W. B.
Published: October 2006

Abstract—

Synaptosomes incubated in a physiological saline extrude sodium and take up potassium. As would be expected this process is completely blocked by metabolic inhibitors such as cyanide and iodoacetate. However, when metabolic inhibitors are replaced by ouabain (100 μM) there is an increase in the steady state intrasynaptosomal sodium and chloride content even though there is no change in the potassium content. The increases are prevented when synaptosomes are incubated with metabolic inhibitors in addition to ouabain. There is therefore a ouabain‐insensitive process that transports sodium, chloride and concomitantly water into synaptosomes. It appears not to function when the supply of metabolic energy is inhibited. The diuretic furosemide (1 mM) in the presence of ouabain inhibits the entry of sodium and chloride without affecting the intrasynaptosomal potassium concentration. Ethacrynic acid (1 mM) has a somewhat similar effect but in addition appears to damage the synaptosome membrane.

Kinetic measurements were made of the uptake of sodium, potassium and chloride under conditions of metabolic inhibition and the permeability constants of the membrane determined. Values of 0.068, 0.117 and 0.032 × 10‐6 (cm s‐1) were found for the permeability constants of the membrane to (respectively) sodium, potassium and chloride. Measurements of the rate of uptake in the presence of ouabain revealed an inwardly directed sodium and chloride flux of 5‐20 pmol cm‐2 s‐1. Calculation of the fluxes from the steady state ion concentrations also reveals an inwardly directed sodium and chloride flux, though of lesser magnitude. The influx of water is less than would be expected to preserve osmotic equality suggesting that the translocation of sodium and chloride is the primary event. Although its function remains uncertain the flux has a considerable effect on the ion content of synaptosomes.
UPTAKE OF TAURINE INTO SUBCELLULAR FRACTIONS OF C‐6 GLIOMA CELLS1
Authors: Sieghart W. , Karobath M.
Published: October 2006

Abstract—

Subcellular fractions from cultured C‐6 glioma cells prepared by methods similar to those for crude synaptosomal fractions of rat cerebral cortex accumulated [35S]taurine as did intact glioma cells. Thus, the accumulation of taurine was dependent on temperature and sodium concentration and sensitive to osmotic shock. The kinetic properties of this uptake are characterized by an apparent Km, of about 25 μm, The properties of taurine uptake into subcellular fractions from C‐6 glioma cells were compared with those of crude synaptosomal fractions and differences could be observed in temperature sensitivity and with metabolic inhibitors, which were less potent in the glioma preparation. Equilibrium density gradient centrifugation of subcellular fractions from glioma cells revealed that particles containing [35S]taurine sediment to a lower buoyant density than mitochondria. But on co‐sedimentation of subcellular fractions from glioma cells with synaptosomal fractions derived from cerebral cortex, differences in the buoyant density between these two preparations could be found. The findings support the possibility of a contamination of synaptosomal fractions with subcellular fractions derived from glial origin.
THE EFFECT OF DIETARY HISTIDINE LEVEL ON THE CARNOSINE CONCENTRATION OF RAT OLFACTORY BULBS
Authors: Chung‐Hwang E. , Khurana H. , Fisher H.
Published: October 2006

Young adult male rats were fed purified diets supplying the maintenance level of the essential amino acids or the same diet devoid of histidine. Animals were sacrificed after 2, 4, 6 and 8 weeks on these diets and olfactory bulbs, whole brains and breast muscle removed for analysis of free histidine and histidinecontaining dipeptides. There was an immediate and sharp drop in the level of carnosine in the olfactory bulb of rats on the histidine‐free diet. By 8 weeks only very small amounts of this dipeptide remained. The carnosine concentration in the olfactory bulbs of the rats receiving the maintenance level of histidine also decreased in comparison with the level maintained on the stock diet; this is believed to reflect the much reduced amount of histidine in the former as compared to the latter diet. Homocarnosine disappeared completely from whole brains of rats within 2 weeks on the histidine‐free diet. Muscle carnosine decreased in both absolute terms and relative to the controls. Anserine was lower relative to the controls, but actually increased in absolute value. Histidine deficiency may be used to study the role of carnosine in olfactory function.
PHOSPHATIDYLINOSITOL AND OTHER LIPIDS IN A MAMMALIAN SYMPATHETIC GANGLION: EFFECTS OF NEURONAL ACTIVITY ON INCORPORATION OF LABELLED INOSITOL, PHOSPHATE, GLYCEROL AND ACETATE1
Authors: Burt D. R. , Larrabee M. G.
Published: October 2006

Abstract— Superior cervical ganglia from adult rats were incubated for 1–6 h in a physiological salt solution containing 32Pi [2‐3H]inositol, [U‐14C]glycerol, or [U‐14C]acetate. Control ganglia were at rest throughout incubation, while the preganglionic nerves of the experimental ganglia were stimulated at 5/s, starting after 1 h of incubation. Responses were monitored by recording the action potentials in a postganglionic nerve. Radioactivity of phospholipids was counted after separation of the lipids by paper chromatography. Specific activity of free inositol and the gamma‐phosphate of ATP were measured, the latter by using the hexokinase reaction with [14C]glucose, isolating the product, and counting its content of 32P and 14C. At rest, labelling of phosphatidylinositol (PI), phosphatidylcholine and phosphatidylethanolamine proceeded at constant rates for at least 8 h with all precursors which entered them, except that labelling with glycerol slowed after 2–4 h. During stimulation the rate of incorporation of 32P into PI approximately doubled, as previously reported. The increased rate remained constant for 3 h and then reverted to approximately the resting rate, although the electrical response continued unabated for 16 h. This decrease in rate of 32P‐labelling of PI in the ganglion could not be accounted for by transport into the postganglionic nerves. In stimulated preparations, after 4 h of incubation the labelling of PI was increased above the resting level by 53 ± 5% (mean ±s.e.m.) with [3H]inositol, 97 ± 6% with 32Pi, 24 ± 6% with [14C]glycerol and −3 ± 10% with [14C]acetate. The increase with glycerol was thus statistically significant, in contrast with the findings of others on brain, where an increase of this size has neither been demonstrated nor excluded. There were no accompanying effects of stimulation on the specific activities of the gamma‐P of ATP or of the free inositol within the ganglion that were sufficient to explain the difference between the labelling of PI with P and that with inositol.
EFFECT OF CHOLINE ON THE RATES OF SYNTHESIS and OF RELEASE OF ACETYLCHOLINE IN THE ELECTRIC ORGAN OF TORPEDO
Authors: Morel N.
Published: October 2006

Abstract— Slices of electric organ of Torpedo marmorata were chopped and incubated in a saline‐urea‐sucrose medium. This preparation of minced tissue exhibited a relative enrichment in ACh and nerve endings, which was attributed to a loss of electroplaque cytoplasm. Electron microscopic controls showed nerve endings of normal morphology, some of them forming ‘chaplets’ separated from electro‐plaques. Miniature endplate potentials were recorded on sealed fragments also present in this preparation. ACh levels remained unchanged during incubation periods as long as 19 h. The time course of the incorporation of [1‐14C]acetate of [2‐14C]pyruvate into ACh pools was studied. These incorporations were similarly affected by the choline added to the medium. In the presence of increasing choline concentrations (up to 10‐4m), the incorporation of [14C]acetate or [14C]pyruvate into ACh increased. They both diminished when choline was added above 10‐4M. The ACh content of the tissue was not affected by added choline. From the constancy of ACh levels in the presence of various choline concentrations and from the steady state of our preparation, we can conclude that the release of transmitter varied in parallel to the incorporation rate of the precursor of the acetyl moiety of ACh. This fact was also found using the efflux of [14C]acetate as an evaluation of ACh release. The values of release calculated by this method were in good agreement with those determined from the incorporations of acetate and pyruvate into ACh. It is suggested that the primary action of choline is on its high affinity carrier system. This triggers a secondary action on the ACh release mechanisms.
LACTOSYLCERAMIDASES IN CANINE GLOBOID CELL LEUKODYSTROPHY1
Authors: Kurczynski T. W. , Fletcher T. F. , Suzuki K.
Published: October 2006

Lactosylceramide‐cleaving activities were examined in the canine form of globoid cell leuko‐dystrophy. Lactosylceramidase I activities were deficient in the brains and livers of affected dogs, while they were intermediate in heterozygous carriers. In contrast, lactosylceramidase II activities were normal in affected dogs. Examination of the total tissue activities, solubilization characteristics, and the behavior in Sephadex G‐200 gel filtration, of the activities of lactosylceramidase I and II, galactosylceramidase, and 4‐methylumbelliferyl β‐galactosidase, indicated that, as in human tissues, lactosylceramidase 1 is probably identical with galactosylceramidase, and that lactosylceramidase II is closely associated with 4‐methylumbelliferyl β‐galactosidase. The canine form of globoid cell leukodystrophy is analogous with the human disease with respect to lactosylceramidases, and the lactosylceramidase I assay system of Wengeret al. (1974) is directly applicable also for canine tissues.
ELEVATED INTRACELLULAR GLYCINE ASSOCIATED WITH HYPOXANTHINE‐GUANINE PHOSPHORIBOSYLTRANSFERASE DEFICIENCY IN GLIOMA CELLS1
Authors: Skaper S. D. , Seegmiller J. E.
Published: October 2006

Abstract— The intracellular concentrations of a number of amino acids were measured in a normal clone of rat glioma cells, and in several independently derived clones selected for gross deficiency of the enzyme hypoxanthine‐guanine phosphoribosyltransferase (HGPRT). A significant, approx 2‐fold increase in the concentration of free glycine was observed in both mutagenized and non‐mutagenized HGPRT deficient clones. The increase in glycine was independent of the phase of cell growth. A similar increase did not occur in HGPRT deficient lymphoblasts.
EFFECTS OF CYTOCHALASIN B ON THE UPTAKES OF MONOSACCHARIDES BY RAT BRAIN SYNAPTOSOMES
Authors: Tan C. H. , Peterson N. A. , RAGHUPATHY E.
Published: October 2006

Abstract— Synaptosomal uptakes of a number of simple carbohydrates were strongly inhibited by cytochalasin B (K1= 7‐9 × 10−8M). Phloretin (K1= 2‐4 × 10−6M) and phloridzin (K1= 3‐4 × 10−4M) were less inhibitory. Cytochalasin B competitively inhibited the uptakes of carbohydrates with saturable transport kinetics. Inhibition of sugar uptake was immediate on addition of cytochalasin B but was promptly reversed upon removal of the drug. Cytochalasin B had no effect on the efflux of D‐glucos‐amine or of the phosphorylated sugar, and did not affect intrasynaptosomal hexokinase(s). The synapto‐somal uptakes of L‐glucose, D‐mannitol, L‐fucose and the N‐acetylated amino sugars were non‐saturable and uninhibited by cytochalasin B. In the case of sugars which enter synaptosomes by both saturable and non‐saturable processes, cytochalasin B could be used to selectively inhibit the saturable uptake components. The resultant non‐saturable cytochalasin‐insensitive uptake rates obtained were found to be widely different among the sugars studied, and must be corrected for in order to estimate accurate kinetic constants of the saturable processes.
TRANSPORT OF TYROSINE, PHENYLALANINE, TRYPTOPHAN AND GLYCINE IN NEUROBLASTOMA CLONES
Authors: Archer Ellen G. , Breakefield Xandra O. , Sharata Mary N.
Published: October 2006

Abstract—

Amino acid transport was studied in three neuroblastoma clones, N‐TD6, which synthesizes norepinephrine, N‐T16, which synthesizes small amounts of serotonin, and N‐S20Y, which synthesizes acetylcholine. All three clones exhibited high‐affinity saturable transport systems for tyrosine, phenylalanine, tryptophan and glycine as well as systems unsaturated at amino acid concentrations of 1 mM in the external medium. Tyrosine, phenylalanine and tryptophan enter all three clones by rapidly exchanging transport systems which appear to be relatively insensitive to lowered external [Na+] or to the presence of 2,4‐dinitrophenol (DNP). Glycine uptake was slower and was much more sensitive to lowered external [Na+] and to the presence of DNP in the medium. Glycine transport in N‐T16 cells was decreased more markedly at low temperature than was transport of the three aromatic amino acids. Km and Vmax values found for saturable transport of tyrosine, phenylalanine and tryptophan were sufficiently low to suggest that, if similar amino acid transport systems exist in neuronal membranes, and if amino acid levels in brain extracellular fluid are similar to levels in plasma, such systems may serve, in conjunction with transport systems in cerebral capillaries, to limit the entry of amino acids into brain cells when blood amino levels are near the normal physiological range.
SOME IMMUNOCHEMICAL CHARACTERISTICS OF W1 AND W2 WOLFGRAM PROTEINS ISOLATED FROM RAT BRAIN MYELIN
Authors: Nussbaum J. L. , Delaunoy J. P. , Mandel P.
Published: October 2006

Abstract—

Starting from a chloroform‐methanol (2: 1 v/v) insoluble pellet of rat brain myelin, two pure proteins W1 and W2 were isolated by sodium dodecylsulphate preparative polyacrylamide gel electrophoresis. Their amino acid composition was compared. Antibodies against these proteins were prepared in rabbits. It was found that the two antigens have common antigenic similarities. The presence of one precipitin line of identity when myelin or isolated W1 and W2 from different animals were tested, led to the conclusion that there was no species specificity. The importance of the availability of such antisera is discussed.