bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract—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.
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.
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

AbstractYoung 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.
LACTOSYLCERAMIDASES IN CANINE GLOBOID CELL LEUKODYSTROPHY1
Authors: Kurczynski T. W. , Fletcher T. F. , Suzuki K. 
Published: October 2006

AbstractLactosylceramide‐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.
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.
AXONAL TRANSPORT IN NIGRO‐NEOSTRIATAL NEURONS DURING MORPHINE TOLERANCE DEVELOPMENT AND ABSTINENCE IN RATS1
Authors: IWAMOTO E. T. , CRAVES F. B. , LOH H. H. , MEYERHOFF J. L. , WAY E. L. 
Published: October 2006

Abstract—Axonal transport of [3H]protein in the nigro‐neostriatal pathway in rats was examined during acute and chronic morphine administration and during morphine abstinence. Two days after a microinjection of [3H]lysine into the left substantia nigra zona compacta, more than 95% of the radioactivity present in the rat forebrain was protein‐bound. Examination of frozen frontal brain sections revealed that 80–90% of the labelled protein of the injected side was located in brain areas traversed by the nigro‐neostriatal pathway. As a positive control, intranigrally administered colchicine reduced the amount of [3H]protein transported after 5 days to the nucleus caudatus‐putamen (neostriatum) to approx 18‐26% of control. In animals rendered morphine‐dependent by subcutaneous implantation of tablets containing 75 mg of morphine base, 27–86% more radioactivity accumulated in the neostriatum at 3, 4 and 5 days after [3H]lysine injection. In contrast, 23–48% less radioactivity was recovered in the neostriatal areas of animals withdrawing from morphine 24 h after [3H]lysine. Gel electrophoresis of soluble and particulate [3H]protein fractions from neostriatal tissues indicated that the gel patterns of radioactivity were not altered by chronic morphine administration. Neither morphine administration nor morphine abstinence altered the rate or amount of [3H]lysine incorporation into protein of the substantia nigra. These data demonstrate that chronic morphine administration was accompanied by a generalized increase in the amount of labelled protein transported to the neostriatum but the procedure was not sufficiently sensitive to detect a minor qualitative alteration of any particular protein(s). Furthermore, these data suggest that either the capacity or the rate of nigro‐neostriatal protein transport may be increased during chronic morphine administration in the rat.
LOCALIZATION OF GABAERGIC, CHOLINERGIC AND AMINERGIC STRUCTURES IN THE MESOLIMBIC SYSTEM
Authors: Fonnum F. , Walaas I. , Iversen E. 
Published: October 2006

Abstract— The localization of cholinergic, GABAergic and aminergic structures in the ‘mesolimbic’ system has been discussed from studies on the topographical distribution of choline acetyltransferase, glutamate decarboxylase and aromatic amino acid decarboxylase in normal rat brain and in brains hemitransected at the level of globus pallidus. The structures analysed included nucleus accumbens, olfactory tubercle, septum, medial forebrain bundle, striatum, substantia nigra, ventral tegmental area and nucleus interpeduncularis.Choline acetyltranferase was highly concentrated in the nucleus interpeduncularis, but it did also exhibit considerable activity in the nucleus accumbens, the olfactory tubercle and the striatum. The activities did not change after hemitransection. Aromatic amino acid decarboxylase was highly concentrated in the ventral tegmental area, but high activities were also found in the striatum, the nucleus accumbens, the olfactory tubercle and the pars compacta of the substantia nigra. The activity decreased in all areas rostral to the hemitransection. Glutamate decarboxylase was highly concentrated in the dopamine innervated regions, moreso in the limbic structures than in the striatum. Much higher activity was found in the substantia nigra than in the ventral tegmental area. After hemitransection the activity in the substantia nigra was decreased whereas in the ventral tegmental area it was unchanged. Our results thus suggest that dopaminergic cells in the ventral tegmental area do not receive GABAergic fibres from the terminal regions of the ascending dopaminergic fibres. In addition, we found a very high concentration of glutamate decarboxylase in a region traversed by the rostral medial forebrain bundle. Here the activity was mainly confined to the paniculate fraction, probably the synaptosomes. This fraction also displayed a very active high affinity uptake of y‐aminobutyric acid.
RAT BRAIN STEM TRYPTOPHAN HYDROXYLASE: MECHANISM OF ACTIVATION BY CALCIUM
Authors: Hamon M. , Bourgoin S. , Artaud F. , Héry F. 
Published: October 2006

Abstract— The activity of soluble tryptophan hydroxylase from rat brain stem was increased in presence of mm concentrations of calcium. Similarly to that observed by treating the enzyme with sodium dodecyl sulphate or trypsin, this activation resulted mainly from an increased affinity of tryptophan hydroxylase for both its substrate, tryptophan, and the cofactor 2‐amino‐4‐hydroxy‐6‐methyl‐5,6,7,8‐tetrahydropteridine (6‐MPH4). In addition, the optimal pH for the enzymic activity was shifted from 7.6 to 7.9 following activation by calcium, sodium dodecyl sulphate or trypsin.Under the assay conditions used for measuring tryptophan hydroxylase activity, calcium also stimulated a neutral proteinase. This latter enzyme could be eliminated from the solution of tryptophan hydroxylase by filtration through Sephadex G 200. The resulting partially purified tryptophan hydroxylase could be activated by calcium only when the neutral proteinase was included in the assay mixture. In support of this conclusion, the effect of calcium on tryptophan hydroxylase was very small in the new born rat when the activity of the neutral proteinase was low. In addition, the activating effect of Ca2+ could be antagonized not only by a chelating agent like EGTA but also (partially) by specific inhibitors of proteinases such as benzethonium and PMSF.These results strongly suggest that the activation of tryptophan hydroxylase by calcium is the consequence of a partial proteolysis of the enzyme by the calcium‐dependent neutral proteinase. Therefore, the physiological significance of this irreversible effect is doubtful.
METHYLHISTAMINE: EVIDENCE FOR SELECTIVE DEAMINATION BY MAO B IN THE RAT BRAIN IN VIVO
Authors: Waldmeier P. C. , Feldtrauer J.‐J. , Maǐtre L. 
Published: October 2006

Abstract— A new method has been developed for the separation of histamine and its metabolites after intracisternal injection of [3H]histamine into the rat brain, involving solvent extraction and subsequent thin‐layer chromatography.The effect of graded doses of the MAO inhibitors deprenil and pargyline, which at relatively low doses inhibit preferentially the B form (phenethylamine deaminating) of the enzyme, and clorgyline, which mainly inhibits the A form (serotonin, noradrenaline and dopamine deaminating) on the brain levels of intracisternally injected [3H]histamine and its labelled metabolites was studied and compared to MAO A and B activity as determined with the substrates serotonin and phenethylamine, respectively. In addition, the time‐course of the effects of a single dose of pargyline (50mg/kg subcutaneously) was investigated. No [3H]imidazoleacetic acid could be detected in any of the control or treated animals. [3H]Histamine accounted for 9–12% of the total extracted radioactivity and this was not altered significantly by pretreatment with any of the MAO inhibitors up to high doses, at which both MAO A and B activities were completely inhibited.In the controls, 40–43% of the total extracted radioactivity was [3H]methylhistamine and 28–30% was [3H]methylimidazoleacetic acid. Deprenil and pargyline caused [3H]methylhistamine levels to increase in a dose‐dependent manner up to about 150% of control levels and those of [3H]methylimida‐zoleacetic acid to decrease concomitantly to about 10% of control levels. Clorgyline in doses up to 10 mg/kg subcutaneously (s.c.) had no effect on the levels of these two metabolites. The dose‐response curves of the effects of deprenil and pargyline on [3H]methylimidazoleacetic acid levels were congruent with those of the MAOI effects on MAO B activity and not with those on MAO A activity.Pargyline (50 mg/kg s.c.) had a long lasting effect on the accumulation of [3H]methylhistamine and [3H]methylimidazoleacetic acid. Recovery occurred within 21 days, and the half‐lives observed were 5.3 and 5.6 days, respectively. This compares well to the half‐life for the recovery of MAO B activity reported earlier after the same dose of pargyline (5.5 days).These results suggest that methylhistamine is metabolized selectively by MAO B in rat brain. Moreover, the fact that clorgyline, at doses where phenethylamine deamination is already considerably inhibited, did not affect the deamination of methylhistamine, suggests that the latter is an even more selective substrate for MAO B than phenethylamine itself.Therefore, small doses of deprenil (0.3–3 mg/kg s.c.) or pargyline (1–3 mg/kg) can be used to influence histamine catabolism without interfering with catecholamine or serotonin deamination.
THE DISTRIBUTION OF NEUROPHYSINS AND POSTERIOR PITUITARY HORMONES IN THE PORCINE NEUROHYPOPHYSEAL SYSTEM
Authors: Dax E. M. , Johnston C. I. 
Published: October 2006

AbstractSpecific, homologous porcine neurophysin I and II radioimmunoassays were established together with specific oxytocin and vasopressin radioimmunoassays. The levels of each of these proteins and peptides were measured in acid extracts of individual paraventricular nuclei, supraoptic nuclei, neurohypophyseal stalks and posterior pituitary lobes of 12 pigs in order to quantitate the neurophysin‐hormone relationships in the porcine neurohypophyseal system. Neurophysin III was found to be immunologically identical to neurophysin I. Neurophysin measurements by radioimmunoassay were quantitatively validated by scanning densitometry of polyacrylamide gels stained with 0.5% amido schwarz.In the hypothalamic nuclei vasopressin was in 3–4 M excess of oxytocin but in the neurohypophyseal stalk and posterior pituitary lobe the hormones were equimolar suggesting that the rate of formation of vasopressin differs from that of oxytocin. Neurophysin I immunoreactivity was present in a 3:1 molar ratio with neurophysin II throughout the porcine neurohypophyseal system. In posterior pituitary lobes total neurophysins were equimolar to total hormone concentrations. The specific activity (pmol/mg extracted protein) of oxytocin increased 1800 times, vasopressin 560 times and neurophysins about 360 times from the paraventricular nucleus to the posterior pituitary lobe. In the hypothalamic nuclei relationships between immunoreactive neurophysin I and vasopressin, and between neurophysin II and oxytocin were highly significant. In the posterior pituitary lobe each immunoreactive neurophysin level correlated with both hormone levels. Quantification of densitometric scans of stained polyacrylamide gels from neurophypophyseal extracts and immunoreactivity patterns of neurophysins in eluates of sliced, duplicate gels indicated that neurophysin III decreased distally within the neurohypophyseal tract while neurophysin I increased. The results demonstrated that vasopressin was associated with porcine neurophysin I. However, oxytocin may be associated with both immunoreactive neurophysin I and neurophysin II in the porcine neurohypophyseal system if a 1:1 molar ratio of neurophysin to hormone is to be maintained. Neurophysin III contributed to the stoichiometry of this relationship.
BIOSYNTHESIS OF S‐ADENOSYL‐L‐METHIONINE IN THE RAT PINEAL GLAND
Authors: Guchhait Ras B. , Grau James E. 
Published: October 2006

AbstractThis investigation provides direct evidence that rat pineal gland contains ATP:L‐methionine S‐adenosyltransferase. The specific activity of the enzyme is about 25 times greater than that of hydroxyindole‐O‐methyltransferase, the unique marker enzyme in this tissue. The major product of the reaction catalyzed by ATP:L‐methionine S‐adenosyltransferase has been identified as S‐adenosyl‐methionine which can function as a methyl group donor for the formation of melatonin. The specific activity of pineal ATP:L‐methionine S‐adenosyltransferase is at least eight times greater than that of brain, and one‐half that of the liver enzyme.
EVIDENCE FOR STRICTLY Na+‐DEPENDENT ACCUMULATION OF SERINE AND THREONINE IN BRAIN CORTICAL SYNAPTOSOMES FROM NEWBORN RATS
Authors: Peterson N. A. , Raghupathy E. 
Published: October 2006

AbstractEvidence is presented in this paper to show that synaptosomal particles derived from brains of immature rats possess two separate, high‐affinity transport systems for the hydroxyamino acids, serine and threonine. One of these is strictly Na+‐dependent and the other Na+‐nondependent. The Km terms of both of these systems have values in the range of 20 μM. Na+‐dependent uptakes of serine and threonine do not take place in synaptosomal particles isolated from of adult animals.