bluuebunny/crossref_metadata_2025 huggingface dataset:
STUDIES ON THE PROPERTIES OF RETINAL ALCOHOL DEHYDROGENASE FROM THE RAT
Authors: Watkins W. D. , Tephly T. R.
Published: October 2006

Abstract—

An NAD‐dependent alcohol dehydrogenase (alcohol:NAD oxidoreductase; EC 1.1.1.1) has been isolated and partially purified from the retinal cytosol of the rat. Its substrate specificity and sensitivity to inhibitors of hepatic alcohol dehydrogenase have been investigated. Ethanol, 1‐propanol and 1‐butanol served as substrates for this enzyme but the Km values were more than 100‐fold higher than those reported for hepatic alcohol dehydrogenase. Methanol and retinol were unreactive with this alcohol dehydrogenase. Inhibition by pyrazole was observed but the Kt was about 100‐fold higher than the value observed for hepatic alcohol dehydrogenase. n‐Butyraldoxime inhibited retinal alcohol dehydrogenase with a Kt of 2 μM, a value which approximates its Kt for hepatic alcohol dehydrogenase. 1, 10‐Phenanthroline was ineffective as an inhibitor. Oxidation of retinol was observed in retinal homogenates in the presence of NADP but no inhibition was observed with ethanol, methanol or pyrazole. We conclude that oxidation of retinol is not catalysed by soluble retinal alcohol dehydrogenase.
QUANTITATIVE HISTOCHEMICAL STUDIES OF FORMALDEHYDE‐INDUCED PARENCHYMAL FLUORESCENCE FOLLOWING L‐DOPA ADMINISTRATION
Authors: Dowson J. H. , Laszlo I.
Published: October 2006

Abstract—

A microfluorimetric method is described for quantitative histochemical study of diffuse formaldehyde‐induced fluorescence in the neuropil of various brain regions and was used to investigate the effects of L‐DOPA in the rat and cat. Regional and species differences in the effects of L‐DOPA on the CNS are reported and discussed.

In the rat, suitable doses of L‐DOPA led to increases in the intensity of fluorescence in the neuropil of the samples of caudate nucleus, which were greater than the increases in the neuropil of the other regions studied. Marked increases in the intensity of fluorescence in the neuropil of the cat brain samples were produced by doses of L‐DOPA/kg body wt. which were too low to produce detectable increases in the fluorescence of the rat brain samples.
RELEASE OF AROMATIC AMINES FROM BRAIN TISSUES OF THE RAT IN VITRO1
Authors: Baldessarini R. J.
Published: October 2006

Abstract—

Radioactive β‐hydroxylated phenylethylamines, DL‐octopamine and DL‐metara‐minol, as well as DL‐norepinephrine, were released from slices or minces of rat brain in vitro by electrical or ionic depolarizing stimuli. In contrast, labelled D‐amphetamine and p‐tyramine were poorly released and the release of urea was barely perceptible. Addition of unlabelled L‐norepinephrine to an incubating medium led to displacement of previously bound [3H]octopamine and [3H]metaraminol from a synaptosomal preparation. Pretreat‐ment of rats with intrathecal 6‐hydroxydopamine markedly decreased the ability of slices of their brains to release [3H]norepinephrine and [3H]octopamine. We suggest that certain phenolic β‐hydroxylated phenylethylamines may enter central, norepinephrine‐containing nerveendings, may be stored in presynaptic vesicles and may be released by nerve stimulation. Under certain circumstances such compounds may act as neurotransmitters with unknown post‐synaptic effects.
STUDIES ON THE ORIGIN OF PYRIMIDINES FOR BIOSYNTHESIS OF NEURAL RNA IN THE RAT
Authors: Hogans Alice F. , Guroff G. , Udenfriend S.
Published: October 2006

Uridine was far superior to orotic acid in labelling the RNA in incubated slices of rat brain. On the other hand, uridine and orotic acid were equally effective in labelling the RNA of hepatic or renal slices In rats in vivo, uridine, but not orotic acid, labelled brain RNA, and the cerebellar RNA contained the most label. In contrast, both uridine and orotic acid labelled hepatic RNA. Only when surgical intervention prevented peripheral metabolism of orotic acid, thereby raising its concentration in the plasma, did neural tissue utilize this precursor for limited biosynthesis of RNA. However, among the tissues studied, the preference for uridine over orotic acid for RNA synthesis was unique to neural tissue.
CORTICOSTERONE BINDING BY RAT BRAIN CYTOSOL1
Authors: Grosser B. I. , Stevens W. , Bruenger F. W. , Reed D. J.
Published: October 2006

Significant quantities of corticosterone were associated with macromolecules of the brain cytosol following intrathecal administration of [3H]corticosterone to adrenalectomized rats. Fifteen times more steroid was found associated with proteins from adrenalectomized rats than from control animals or adrenalectomized animals pretreated with corticosterone. Pretreatment of adrenalectomized rats with 11‐dehydrocorticosterone, Cortisol and cortisone decreased the amount of [3H]corticosterone found associated with protein, whereas progesterone, oestradiol and testosterone did not interfere with the association of [3H]corticosterone with macromolecules of the cytosol. Further evidence for protein‐steroid interaction was obtained by incubating [3H]corticosterone (B), [3H]cortisol (F), or 11‐[3H]deoxycortisol (S) with brain cytosols. The degree of binding was in the order B > F > S.
THE INFLUENCE OF INTRAVENTRICULARLY INJECTED AMINO ACID EXCITANTS ON THE LABELLING OF ENDOGENOUS BRAIN AMINO ACIDS FROM [U‐14C]ACETATE IN NEMBUTALIZED MICE
Authors: Watkins J. C.
Published: October 2006

Mice were anaesthetized with nembutal and the effects of intraventricularly injected excitant amino acids on [U‐14C]acetate metabolism were investigated. The natural excitant amino acids, l‐glutamate and l‐aspartate, reduced the incorporation of 14C from [U‐14C]acetate into glutamine, GAB A and possibly alanine. The synthetic excitant amino acid, N‐methyl‐d‐aspartate caused a reduction in the incorporation of 14C from intraventricularly injected [U‐14C]acetate into all of the brain amino acids labelled by [U‐14C]acetate within 5 min. It is suggested that these effects may be due to changes in pool sizes of tricarboxylic cycle intermediates, to inhibition of acetyl‐CoA formation, or both. Differences in the metabolic effects of the synthetic and natural excitants are interpreted in terms of the uptake of the natural amino acids into glutamine‐forming pool(s) of glutamate metabolism.
EFFECT OF HAEMORRHAGE ON THE RAPID AXONAL TRANSPORT OF NEUROHYPOPHYSIAL PROTEINS OF THE RAT
Authors: Norströ A. , Sjöstrand J.
Published: October 2006

Following injection of [35S]cysteine into the region of the supraoptic nucleus male rats were subjected to haemorrhage and the radioactivity of the supraoptic nucleus and neurohypophysial proteins was measured at various time intervals after injection. Following haemorrhage the incorporation of [35S]cysteine into supraoptic nucleus proteins increased. Evidence was obtained for a lag period of 1 to 2 h for the supraoptic nucleus proteins to become available for axonal transport. As judged from the time of arrival of labelled material in the neurohypophysis, haemorrhage did not change the rapid rate of axonal transport (190 mm/day). At 15 min following bleeding, the radioactivity in fraction A (a neurophysin) of the neurohypophysis was reduced, which indicated a release of this rapidly transported protein. During the following 15 min an increase in the protein‐bound radioactivity of the neural lobe occurred which exceeded that in controls. This is taken as evidence for increased axonal transport in response to haemorrhage.
AGE‐DEPENDENT VARIATIONS OF THE HUMAN N‐ACETYL‐β‐D‐HEXOSAMINIDASES
Authors: Harzer K. , Sandhoff K.
Published: October 2006

The total N‐acetyl‐β‐d‐hexosaminidase (hexosaminidase A plus B) activity of the human brain increases during life until the age of 70 years to about twice the activity found in the foetal brain. This activity roughly parallels the increasing level of brain ganglio‐sides. Simultaneously, the ratio between the hexosaminidases A and B changes from approx. 3.4 to 1.1 as established by the microscale isoelectric focussing of the enzymes from crude extracts. Age‐dependent variations can be also demonstrated for other glycosidase activities: The β‐d‐glucosidase is shown to increase, the α‐d‐mannosidase and α‐l‐fucosidase to decrease during life. The enzyme values are related to the protein content, the age‐dependent shift of which we have determined in the human brain. In different organs and body liquids distinct differences are found for the levels of the total hexosaminidase activity as well as for the hexosaminidase pattern. The relation of the hexosaminidase activity to the ganglioside degradation during the human development is discussed.
DEVELOPMENT OF THE UPTAKE AND STORAGE OF L‐[3H]NOREPINEPHRINE IN THE RAT BRAIN
Authors: Coyle J. T. , Axelrod J.
Published: October 2006

The uptake and storage of L‐[3H]norepinephrine at various stages of development was examined in homogenates of rat brain. For the adult animal, active uptake accounted for 80 per cent of the total uptake. At 14 days of gestation, no active uptake was demonstrable At 18 days of gestation, saturable uptake of L‐[3H]norepinephrine with a Km of 3 × 10 −7m was first demonstrable; the Km value did not vary during subsequent development. The Vmax. of uptake increased five‐fold between 18 days of gestation and 28 days postnatally, at which stage it was the same as the adult value. The development of saturable uptake paralleled but preceded the increase in endogenous norepinephrine. When homogenates were incubated with l‐[3H]norepinephrine and subjected to centrifugation on linear sucrose gradients, there was a peak of tritium in the synaptosomal fractions; the magnitude of the peak increased with maturation of the brain. The increase in the peak of tritium paralleled the increase in particulate LDH activity and was distinct from the peak of MAO activity. Desipramine, a compound that blocks the initial uptake of norepinephrine, first exhibited inhibition of uptake at 19 days of gestation; the degree of inhibition did not vary during subsequent development. In contrast, reserpine, a compound which inhibits the intra‐neuronal storage of norepinephrine, exhibited a progressive increase of inhibition with maturation of the brain at and subsequent to 19 days of gestation.
EFFLUX OF ENDOGENOUS PROTEIN FROM NON‐MYELINATED OLFACTORY NERVE AS MONITORED BY TRYPTOPHAN FLUORESCENCE
Authors: Hines J. F. , Easton D. M.
Published: October 2006

Endogenous protein was lost from the olfactory nerve of the garfish (Lepisosteus osseus) when the excised but excitable nerve was bathed with normal physiological solution. The protein could be detected by its fluorescence at 340 nm when excited at 280 nm. The relative concentrations were expressed in terms of an equivalent fluorescence from a standard solution of tryptophan. From an initial fluorescence, equivalent to 5 × 10−10 mol of tryptophan/mg of nerve washed out during each 10 min, the efflux may decline slowly in rate to 10−11 mol/mg per 10 min. Depolarizing direct current or a several‐fold increase of the concentration of KCl in the bathing solution might transiently double the rate of efflux above the resting rate during continuous monitoring of the fluorescence intensity. Changes in concentrations of external KCl, glucose or sucrose, in ionic strength (at constant osmolality), or in osmolality all produced a transient increase of fluorescence in the effluent from the nerve. An increase followed both introduction of the experimental solution and the return to the control solution. We interpreted the increase in intensity of fluorescence of the washout solution to indicate an increase in concentration of an intrinsic specific protein washed from the nerve. By electrophoresis, a single acidic fluorescent protein band was observed travelling with the marking dye. Chromatographic fractionation on Sephadex suggested a mol. wt. in excess of 100,000.
ISOLATION AND ELECTROPHORETIC IDENTIFICATION OF HISTONES OF RAT BRAIN AND LIVER
Authors: Duerre J. A. , Gaitonde M. K.
Published: October 2006

Abstract—

Relatively pure brain nuclei were prepared on a discontinuous sucrose gradient which gave yields of between 40 and 60 per cent.

An extraction procedure has been developed for the isolation of total histones from brain and liver nuclei. This procedure is also applicable to the isolation of histones directly from whole brain and liver.

The electrophoretic pattern of histones prepared from brain and liver by the above procedure was similar to that of calf thymus histones.
UPTAKE AND METABOLISM OF [3H]NOREPINEPHRINE IN THE CEREBRAL HEMISPHERES OF CHICK EMBRYOS1,2
Authors: Kellogg C. , Vernadakis A. , Rutledge C. O.
Published: October 2006

Abstract— The uptake and metabolism of [3H]norepinephrine were studied in slices of cerebral hemispheres removed from chick embryos at 10, 15 and 20 days of embryonic age, as well as from 90‐day‐old hens. Brain tissue from all age groups concentrated [3H]norepinephrine to much greater levels at 37°C than at 0°C. There was a marked increase in the rate of accumulation of [3H]norepinephrine in tissues from 10 to 15 days of embryonic age, with no further increase in the rate observed from 15 to 20 days of embryonic age.

Tissue slices were incubated for 20 min with [3H]norepinephrine, and the deaminated metabolites of norepinephrine were separated by paper chromatography. In tissues from all age groups, the neutral metabolites were produced in greater amounts than the acid metabolites. A significant increase in the amounts of deaminated metabolites formed was observed in the period from 10 to 15 days of embryonic age and a significant decrease in the amounts formed was observed in the period from 15 to 20 days of embryonic age. The deamination at 20 days was very similar to that observed in the adult.

A significant decrease in the level of the deaminated metabolites was noted in all age groups in response to cocaine (an inhibitor of neuronal uptake mechanisms), an observation suggesting that mechanisms for neuronal uptake of NE are functional by 10 days of embryonic development in the chick. However, a significant increase in the level of deaminated metabolites in response to reserpine (an inhibitor of uptake of NE into storage granules) was observed only in slices taken from 20‐day embryos and from the 90‐day‐old hen. The effect in the hen was more prominent than in the 20‐day embryo. These results were interpreted to indicate that mechanisms for the uptake of NE develop at an earlier embryonic age than mechanisms for the storage of NE and that mechanisms for storage continue to develop after hatching.
PROTEIN SYNTHESIS IN VITRO IN NUCLEI OF HUMAN NERVOUS TISSUE
Authors: Haglid K. G.
Published: October 2006

Abstract—

In vitro incorporation of tritiated leucine into nuclear proteins of normal human brain, astrocytoma I and II and glioblastoma multiforme was investigated. The distribution of radioactivity among various protein fractions of nuclei was determined.

The results demonstrate that the isolated nuclei of astrocytoma I and II incorporate radioactivity into proteins at least 40 times more actively than nuclei of normal human brain or glioblastoma multiforme.

The residual protein fraction was the most highly labelled fraction among the nuclear pioteins. This fraction from astrocytomas incorporates relatively more radioactivity than the similar fraction of normal human brain or glioblastoma multiforme. The buffered‐saline soluble protein fraction of astrocytoma nuclei contained a relatively lower amount of radioactivity than the similar fraction of normal human brain or glioblastoma multiforme. The total radioactivity incorporated into the deoxyribonucleoproteins seemed to increase with the malignancy of the tissue investigated. The significance of the results with respect to malignant transformation is discussed.
THE BIOSYNTHESIS OF CHOLESTEROL AND OTHER STEROLS BY BRAIN TISSUE
Authors: Ramsey R. B. , Jones J. P. , Rios A. , Nicholas H. J.
Published: October 2006

Abstract— The distribution of [14C]‐labeIled material into subcellular fractions of 15‐day‐old rat brain was studied as a function of time after intracerebral injection of [2‐14C]mevalonic acid. As previously shown for adult brain, the data indicated the microsomal fraction to be the site of sterol biosynthesis. The synaptosomal fraction exhibited a marked early uptake of [14C]‐nonsaponifiable material. Total radioactivity in both myelin and myelin‐like fractions remained low in comparison to that in the other subcellular fractions at all time periods examined. At 2 h after injection, labelled digitonin‐precipitable material was demonstrable in all subcellular fractions. Examination of the [14C]‐labelled nonsaponifiable material by thin‐layer chromatography indicated the rapid appearance of labelled 4‐desmethyl sterol in all subcellular fractions, with the most rapid appearance in the myelin fraction, followed in decreasing order by microsomal, synaptosomal, and mitochondrial fractions. Examination of [14C] digitonin‐precipitable material from each fraction by the dibromide method demonstrated that although 4‐desmethyl sterol appeared quickly, the formation of cholesterol was slow in all fractions, an effect that had been reported earlier for adult brain.
ALLOSTERIC ACTIVATION OF HYPOTHALAMIC TYROSINE HYDROXYLASE BY IONS AND SULPHATED MUCOPOLYSACCHARIDES
Authors: Kuczenski R. T. , Mandell A. J.
Published: October 2006

Abstract— The kinetics of canine hypothalamic tyrosine hydroxylase were studied in the presence of various ions and sulphated mucopolysaccharides. Enzymic activity was dependent on ionic strength, a specific sulphate effect and the presence of the highly sulphated mucopolysaccharide, heparin. Whereas both sulphate and heparin activated tyrosine hydroxylase by increasing Vmax heparin, but not sulphate, also increased the affinity of the enzyme for the synthetic cofactor, 2‐amino‐4‐hydroxy‐6,7‐dirnethyl‐5,6,7,8‐tetrahydropteridine, by nearly an order of magnitude. Other rnucopolysaccharides, such as chondroitin sulphate and hyaluronic acid, were not effective as activators of tyrosine hydroxylase. The allosteric activation of tyrosine hydroxylase by heparin may serve to ‘sensitize’ the enzyme to low levels of its end product, norepinephrine.
DEMONSTRATION OF ACETYLCHOLINE RELEASE BY MEASURING EFFLUX OF LABELLED CHOLINE FROM CEREBRAL CORTICAL SLICES
Authors: Somogyi G. T. , Szerb J. C.
Published: October 2006

Abstract— To demonstrate release of ACh in the absence of inhibition of cholinesterase, slices of cerebral cortex were incubated with [3H]choline, after which they were placed in a tissue bath for superfusion. Hemicholinium (HC‐3) increased the spontaneous efflux of [3H]choline. Electrical stimulation at 4/s increased the efflux of [3H]choline to the same extent whether the slices were stimulated early or late during superfusion. The effect of stimulation on efflux of [3H]choline was abolished by tetrodotoxin and by the absence of calcium. The extent of choline efflux resulting from stimulation, as calculated from the specific radioactivity of the incubation medium, was the same when the slices were incubated with 0.1 or 1.0mM choline, but was less with lower concentrations of choline. We conclude that the increased efflux of [3H]choline evoked by stimulation probably originates from stores of [3H]ACh synthetized during incubation.
COMPARTMENTATION AND LABELLING OF AMINO ACIDS IN THE DEVELOPING RAT BRAIN AFTER INJECTION OF [U‐14C]RIBOSE
Authors: Gaitonde M. K. , Kelly Roisin
Published: October 2006

Abstract— [U‐14C]Ribose was given by subcutaneous injection to young rats aged 2–56 days. During the first week after birth 14C in the brain was found mainly combined in glucose, fructose and sedoheptulose which contained 46–57 per cent of the 14C in the acid soluble metabolites in the rat brain. In contrast, during the critical period (10–15 days after birth) the 14C in the free sugars decreased from 24 to 3 per cent, while the 14C content of amino acids in the brain increased from 11 to 44 per cent of the total perchloric acid‐soluble 14C. The increase in labelling of amino acids during the critical period was attributed to increased glycolysis and increased oxidation of pyruvate. The relative specific radioactivity of y‐aminobutyrate and aspartate in the rat brain at 28 days after birth was equal to or greater than the relative specific radioactivity of glutamate. Assuming that the increase in amino acid content following the cessation of cell proliferation in the brain is located mainly in cell processes (cytoplasm of axons, dendrites, glial processes and nerve terminals), tentative values were estimated for the pool sizes of glutamate, glutamine, aspartate and y‐amino butyrate.
THE EFFECT OF DIETHYL‐α‐FLUOROGLUTARATE ON PHOSPHATES AND GLUTAMATE IN SLICES OF RABBIT CEREBRAL CORTEX1
Authors: Cohen H. P. , Lin S.
Published: October 2006

Abstract— The diethyl ester of α‐fluoroglutarate (DEFG), an inhibitor of glutamate dehydrogenase, was prepared, and its effect on glutamate and phosphates in slices of rabbit cerebral cortex was examined. The primary effect of the drug on cortical slices incubating in a Krebs‐Ringer glucose medium was to decrease the tissue levels of glutamate in association with decreased levels and turnover of high‐energy phosphates. Assimilation of exogenous glutamate by the slices was partially blocked in the presence of the drug and severely depressed oxidative phosphorylation resulted when glutamate and DEFG were both present in the incubation mixture. The results suggested a significant relationship between the activity of cerebral glutamate dehydrogenase and oxidative phosphorylation.

During incubation in a Krebs‐Ringer glucose medium the endogenous pool of free amino acids in the cortical slice partitioned with the medium. Little or no glutamate, aspartate or GABA was present in the medium after incubation, but glycine, alanine, threonine, serine and glutamine did partition to varying degrees, with over one‐half of the glutamine present in the incubation medium. With the exception of ‘leakage’ of aspartate, the partitioning patterns were relatively unaffected by the presence of added glutamate or DEFG.
EXPERIMENTAL ALCOHOLISM IN RATS: PROTEIN SYNTHESIS IN SUBCELLULAR FRACTIONS FROM CEREBELLUM, CEREBRAL CORTEX AND LIVER AFTER LONG TERM TREATMENT1
Authors: Jarlstedt J.
Published: October 2006

Abstract— The incorporation in vivo of [3H]leucine into protein from subcellular fractions was determined in rats chronically ingesting 15 per cent ethanol for 8 months. Mitochondrial, microsomal and cell sap fractions from cerebellum, cortex cerebri and liver were investigated. The results showed a minor over‐all depression of protein synthesis in cerebellum and cortex cerebri and a slight stimulation of the incorporation of leucine into protein from liver subcellular fractions. If the animals were abstinent 24 h before injection of the isotope, the incorporation of labelled amino acids into protein was markedly increased in cerebellum and cerebral cortex but not in liver.
Rat brain polysomal profiles: a study of their stability in vitro
Authors: Wasterlain C. G.
Published: October 2006

Modifications of the profiles of brain polysomes have been interpreted as having pathological significance (Aoki and Siegel, 1970; Vesco and Giuditta, 1968). However, profiles of polysomes obtained from brains of healthy animals vary greatly with the method of extraction (Roberts and Zomzely, 1966) and we do not know whether they accurately reflect the distribution in oioo of polysomes and ribosomal subunits. In exponentially growing E. coli, the large proportion of 70s ribosomes found in polysomal profiles is an artifact resulting from the aggregation in vitro of ribosomal subunits (Phillips, Hotham‐Iglewski and Franklin, 1969a, b). In the present study we sought to determine whether similar changes reflecting instability of some components or in vitro aggregation are likely to occur in polysomes from rat brain. Initially we have investigated the effects of various monovalent cations on the profiles of brain polysomes and the aggregation in vitro of ribosomal subunits.
THE LIMITED PROTEOLYSIS OF BOVINE NEUROPHYSINS BY CATHEPSIN D
Authors: Pickup J. C. , Hope D. B.
Published: October 2006

Abstract— The limited proteolysis of the bovine neurophysins at acid pH has been studied and the enzyme responsible has been characterized. Only 15 per cent of the catheptic activity in 4‐year‐old acetone‐dried posterior pituitary lobe powder is soluble at pH 4.0. Solubility increases as the age of the powder decreases and the cathepsin is completely soluble in the presence of 1% Triton X‐100. Acid proteinase activity in the neurohypophysis is not thiol activated and is inhibited by 3‐phenylpyruvic acid. Bovine serum albumin was degraded at only 1 per cent of the rate of haemoglobin but with the same pH optimum (3.7). On this basis the enzyme was identified as cathepsin D.

Neurophysin‐I is degraded in two stages by cathepsin D; the first product (neurophysin‐I′) runs faster and the second product (neurophysin‐I″) runs slower than the native protein on starch‐gel electrophoresis at pH 8.1. Neurophysin‐II is also degraded in two stages; the first product has a higher electrophoretic mobility than the native protein and is identical in mobility with the faster‐running component of the so‐called neurophysin‐M of Hollenberg and Hope (1967b). Prolonged incubation with the cathepsin gives rise to a slower‐running component. Neurophysin‐C is not attacked by the acid proteinase. Neurophysin‐I′ and I″ have been isolated by ion‐exchange chromotography. They have the same N‐terminal amino acid (alanine) and C‐terminal sequence (Ala‐Phe‐Ser) as the native protein and both bind 8‐argininevasopressin. Neurophysin‐I′ is identical in amino acid composition with the native protein but neurophysin‐I″ has lost one leucine and two aspartic acid residues.

Reduction, 14C‐alkylation and separation of the fragments by starch‐gel electrophoresis shows that the structural and functional integrity of neurophysin‐I″ is maintained by the disulphide bonds, even though a tripeptide has been split out of the interior of the molecule. The low molecular weight material produced by catheptic digestion of neurophysin‐I has been purified and shown to have a composition of one leucine and two aspartic acid residues. It is suggested that extensive in vivo proteolysis of neurophysin by lysosomal cathepsin, with consequent abolition of hormone‐binding ability, is unlikely.
ALTERATION OF GABA SYSTEM AND PURKINJE CELLS IN RAT CEREBELLUM BY THE CONVULSANT 3‐MERCAPTOPROPIONIC ACID
Authors: Rodríguez de Lores Arnaiz Georgina , Alberici de Canal Martha , De Robertis E.
Published: October 2006

Abstract— The effect of the convulsant, 3‐mercaptopropionic acid (MP) on the content of free amino acids and on the activity of some enzymes related to their metabolism was studied in the rat cerebellum. A decrease in the activity of glutamate decarboxylase (EC 4.1.1.15) and in the level of GABA was found; at the same time, the activity of GABA‐aminotransferase (EC 2.6.1.19) was increased. These changes coincided with a profound alteration of the morphology of the Purkinje cells which was related to the dose of MP. These findings, plus some changes in the content of other free amino acids and the activities of related enzymes, suggest that 3‐mercaptopropionic acid induces in the cerebellum an imbalance among the amino acids involved in the excitation‐inhibition mechanisms.
LES COMPARTIMENTS D'ACETYLCHOLINE DE L'ORGANE ELECTRIQUE DE LA TORPILLE ET LEURS MODIFICATIONS PAR LA STIMULATION
Authors: Dunant Y. , Gautron J. , Israël M. , Lesbats B. , Manaranche R.
Published: October 2006

Résumé— L'acétylcholine ‘libre’ et ‘liée’ a été mesurée avant et après stimulation de l'organe électrique de la Torpille in vivo ou in vitro, sur des tranches de tissu incubées dans une solution physiologique. Des potentiels de plaque miniatures peuvent être enregistrés. Des déharges d'une amplitude atteignant 30 V ont été obtenues après stimulation du tissu. La réponse électrique décroît rapidement lors de stimulations répétitives. L'acétylcholine ‘libre’ est celle qui est hydrolysée en cours d'homogénéisation par les estérases du tissu, l'acétyl‐choline ‘liée’ ne l'est pas. Dans l'homogénat, cette dernière est associée aux vésicules synaptiques. L'acétylcholine ‘libre’ est mesurée par la différence entre l'acétylcholine totale et l'acétylcholine ‘liée’. Une baisse d'acétylcholine ‘libre’ est mise en évidence lorsque la réponse électrophysiologique est épuisée par la stimulation. La chute d'acétylcholine ‘libre’ est, comme l'amplitude de la déharge, dépendante du rapport Ca2+/Mg2+. Dans d'autres expériences une diminution des deux compartiments a été notée à la fin de la période de stimulation. Cependant nous avons aussi observé successivement la chute de l'acétylcholine ‘libre’ puis celle de l'acétylcholine ‘liée’ lorsque la stimulation est poursuivie. En présence d'inhibiteurs d'estérase on peut recueillir de l'acétylcholine libérée par stimulation dans la solution physiologique. Une préincubation des tissus avec de la [14C]choline permet de marquer les compartiments d'acétylcholine. La radioactivité spéifique varie dans le compartiment ‘libre’ aprés une série de stimulations, alors qu'elle reste stable dans le compartiment ‘lié’. Ces résultats indiquent que l'acétylcholine ‘libre’ représente un compartiment immédiatement disponible, libéré quand on stimule le tissu.
THE PREPARATION OF CHOLINERGIC SYNAPTOSOMES FROM BOVINE SUPERIOR CERVICAL GANGLIA
Authors: Wilson W. S. , Cooper J. R.
Published: October 2006

—A method is described for the preparation of relatively pure cholinergic synaptosomes from bovine cervical sympathetic ganglia. After dispersion of the tissue by incubation with collagenase, differential centrifugation yielded a crude synaptosomal fraction (P2), which was further purified by centrifugation on sucrose or Ficoll‐sucrose density gradients. Assay of acetylcholine and choline acetyltransferase, and electron microscopy confirmed that presynaptic nerve endings survived the incubation procedure, appeared in the P2 fraction and thereafter sedimented to a density of approx. 1.13 in sucrose and 1.06 in Ficoll‐sucrose. The washed P2 fraction had an acetylcholine content of 2.3 nmol/mg of protein, which is at least three times higher than the corresponding fraction from brain.
SUBCELLULAR DISTRIBUTION OF POTASSIUM, SODIUM, MAGNESIUM, CALCIUM AND CHLORIDE IN CEREBRAL CORTEX1
Authors: Hanig Ruth C. , Tachiki K. H. , Aprison M. H.
Published: October 2006

The subcellular distributions of potassium, sodium, magnesium, calcium and chloride have been determined for rabbit cerebral cortex. After homogenization and differential centrifugation, the following percentages of ions were associated with the particulate fraction (nuclear, mitochondrial, synaptic vesicles, and microsomal): (a) 19% of the total potassium; (b) 22% of the total sodium; (c) 77% of the total calcium; (d) 69% of the total magnesium; and (e) less than 2% of the total chloride. However, the sum of the potassium and sodium content in each of the particulate fractions was greater than the sum of the calcium and magnesium content. After hypo‐osmotic shock of the crude mitochondrial fraction (MT), more sodium than potassium (μmol/g wet wt.) was associated with the mitochondrial (M1) and synaptic vesicle (M2) fractions. The molar ratio of sodium to potassium was 1·4 for M1 and 4·5 for M2. The association of 22Na+ with the particulate fractions was further studied by the method of equilibrium dialysis. The data from both types of experiments indicate that a large fraction of the sodium in cortical tissue appears to be in a bound state.
INCREASE OF BRAIN TRYPTOPHAN BY ELECTROCONVULSIVE SHOCK IN RATS
Authors: Tagliamonte A. , Tagliamonte P. , Chiara G. Di , Gessa R. , Gessa G. L.
Published: October 2006

—ECS markedly increased tryptophan and 5‐hydroxyindoleacetic acid levels in brain. Brain serotonin and plasma tryptophan levels were unaffected.
OCCURRENCE AND DISTRIBUTION OF AROMATIC l‐AMINO ACID (l‐DOPA) DECARBOXYLASE IN THE HUMAN BRAIN
Authors: Lloyd K. G. , Hornykiewicz O.
Published: October 2006

—The enzymatic decarboxylation of l‐DOPA was measured in isotonic dextrose homogenates of different regions of the human brain by estimating 14CO2 evolved from tracer amounts of d l‐DOPA[carboxy1‐14C]. Enzyme activity was linear with respect to tissue concentration and time of incubation. The reaction exhibited a pH maximum at 7·0, was completely dependent upon the presence of high concentrations of pyridoxal phosphate, proceeded at the same rate in an atmosphere of air and nitrogen, and produced dopamine in addition to CO2 as a reaction product. The enzyme preparation behaved like an aromatic l‐amino acid decarboxylase: it also decarboxylated o‐tyrosine and when incubated with 5‐hydroxytryptophan, serotonin was isolated as the reaction product; but it was devoid of activity towards d‐DOPA[carboxy1‐14C]. Within the human brain, l‐DOPA decarboxylase was most active in the putamen and caudate nucleus; the pineal gland, hypothalamus, and the reticular formation and dorsal raphe areas of the mesencephalon exhibited considerable activity. Areas of cerebral cortex exhibited very low enzymatic activity and in regions composed predominantly of white matter, l‐DOPA decarboxylase activity was not significantly above blank values. The activity of l‐DOPA decarboxylase in the human putamen and caudate nucleus tended to decrease with the age of the patients; in comparatively young subjects (46 yr old) the enzyme activity compared favourably with that found, by means of the same assay technique, in the caudate nucleus of the cat.
THE ROLE OF NERVE GROWTH FACTOR IN THE RAMIFICATION OF SYMPATHETIC NERVE FIBRES INTO THE RAT IRIS IN ORGAN CULTURE
Authors: Johnson D. G. , Silberstein S. D. , Hanbauer I. , Kopin I. J.
Published: October 2006

Small amounts of nerve growth factor (NGF) were present in the superior cervical ganglion and the iris of the rat. The observations that NGF content in each of the tissues was depleted during organ culture and that more NGF appeared in the media than was originally present in the tissues indicated that synthesis or activation of NGF had occurred in organ culture. Antibody to NGF or the depletion of endogenous NGF retarded growth of new sympathetic axons into irides in organ culture. Exogenously added NGF appeared to enhance the initiation of axonal sprouting and the rate of the ramification of nerve fibres.
IDENTIFICATION AND CHARACTERIZATION OF WATER SOLUBLE RAT BRAIN ANTIGENS I. BRAIN AND SPECIES SPECIFICITY
Authors: Bock Elisabeth
Published: October 2006

—Some new immunoelectrophoretic methods were applied to the study of brain and species specificity of water‐soluble rat brain antigens. Five antigens were brain specific and one, a brain specific antigen, was species restricted.
EFFECTS OF 5‐PHENYLOXAZOLIDINEDIONE ON SODIUM–POTASSIUM–MAGNESIUM‐ACTIVATED ADENOSINE TRIPHOSPHATASE ACTIVITY IN MOUSE BRAIN1
Authors: Brink J. J. , Freeman Ellen A.
Published: October 2006

—10 μm 5‐Phenyloxazolidinedione (PKO) stimulated Na–K–Mg‐ATPase activity in mouse brain homogenates by 45%. This activation effect was also observed for trimethadione and dimethadione. Inhibition of Na–K–Mg‐ATPase by 0.1 mm ouabain was reduced in the presence of PKO. When PKO (4 mg/kg) was administered to mice intravenously, maximum levels of 2 μg (10 nmol)/g were attained in the brain within 15 min. PKO had an ld50 of 872 mg/kg and an ed50 of 375 mg/kg for protection against metrazol‐induced seizures in mice.
EFFECTS OF GAMMA‐HYDROXYBUTYRIC ACID AND OTHER HYPNOTICS ON GLUCOSE UPTAKE IN VIVO AND IN VITRO
Authors: Taberner P. V.
Published: October 2006

Abstract— (1) The effects of gamma‐hydroxybutyrate, imidazole‐4‐acetic acid and pento‐barbitone on mouse brain glucose, glycogen and lactate levels have been studied. All the drugs significantly increased the brain glucose content, but did not significantly alter brain glycogen levels. The increase in brain glucose following imidazole‐4‐acetic acid or hypnotic doses of pentobarbitone was matched by corresponding decreases in the lactate level; this was not the case with gamma‐hydroxybutyrate where the total glucose equivalents in the brain, expressed as the tissue level of (glucose) + (lactate/2), were significantly increased.

(2) All drugs except imidazole‐4‐acetic acid significantly decreased the rate of appearance of [14C]glucose into the bloodstream in vivo but had no effect on the uptake of glucose into rat diaphragm in vitro when present at 2·5 mM concentration.

(3) Only imidazole‐4‐acetic acid significantly inhibited glucose uptake into the brain in vivo but at 2·5 mM had no significant effect on glucose uptake into rat cerebral cortical slices in vitro.

(4) It is concluded that the very large increase in brain glucose level observed following the injection of hypnotic doses of gamma‐hydroxybutyrate cannot be explained in terms of an increased net uptake of glucose into the brain.
DISTRIBUTION OF SERUM PROTEINS AND BETA‐TRACE PROTEIN WITHIN THE NERVOUS SYSTEM
Authors: Olson J‐E. , Link H.
Published: October 2006

Abstract— The concentration of beta‐trace protein, a low molecular weight water‐soluble protein, was significantly higher in cerebral and cerebellar white matter than in grey matter. A similar distribution was found for transferrin. The concentrations of gamma‐trace protein and pre‐albumin were almost constant in cerebral and cerebellar white and grey matter. A different distribution was shown for albumin, betalc/betalA globulins, and the immunoglobulins G, A and M, with the highest concentrations mostly encountered in the highly vascularized basal ganglia and grey matter, and the lowest concentrations in white matter. Thus, different parameters, hitherto unknown determine the distribution within the central nervous system of various proteins‐those which originate from serum, and beta‐trace protein which originates mainly from the central nervous system.

The amounts of the different proteins were higher in the choroid plexus than in brain tissue, with the exception of gamma‐trace protein.

Foetal brains contained increasing concentrations of beta‐trace protein and of transferrin with age.

Femoral nerve contained lower concentrations of beta‐trace protein and gamma‐trace protein, and higher concentrations of the other proteins, than the central nervous system.
SYNTHESIS OF GLYCOPROTEINS IN BRAIN: IDENTIFICATION, PURIFICATION AND PROPERTIES OF A SYNAPTOSOMAL SIALYL TRANSFERASE UTILIZING ENDOGENOUS AND EXOGENOUS ACCEPTORS1
Authors: BOSMANN H. B.
Published: October 2006

Abstract— Synaptosomes from guinea‐pig cerebral cortex contain a fetuin: sialyl glyco‐protein: glycosyl transferase; evidence is presented which indicates that both a sialyl transferase; evidence is presented which indicates that both a sialyl transferase and endogenous acceptors were located in the synaptosome ‘ghost’ fractions. Following solubilization of synaptosomes with Triton X‐100 and the use of fetuin minus NANA as acceptor, 25 per cent of the transferase was recovered after centrifugation and column chromatography on Sephadex G‐100 and G‐200 with a 64·0‐fold purification. The enzyme had a pH optimum of 6·3, required no divalent metal cation for activity, and exhibited high activity with either fetuin minus sialic acid, prothrombin minus sialic acid, Tamm‐Horsfall glycoprotein minus sialic acid, or orosomucoid minus sialic acid as acceptor; neither BSM nor PSM minus NANA functioned as an effective acceptor. The fetuin:sialyl transferase using fetuin minus sialic acid and CMP‐sialic acid as substrates a and b, respectively, gave the following kinetic constants when using the Cleland bisubstrate model: Ka= 35μM; Kb= 3 μM; Kia, = 25 μM; Kib= 25μM; and V1= 92 pmoles. min−1.mg−1 of protein. The following divalent cations inhibited the reaction: Ba2+ > Hg2+ > Pb2+ > Cu2+.
Tyrosine hydroxylase activity in rat brain following “REM” sleep deprivation
Authors: Sinha A. K. , Claranello R. D. , Dement W. C. , Barchas J. D.
Published: October 2006

In Recent years biogenic amines have been implicated in the control mechanism for induction and maintenance of sleep processes (Jouvet, 1969). Investigators have looked for changes in the rate of synthesis of cerebral norepinephrine from [3H]tyrosine after REM sleep deprivation and reported increased rates of synthesis during REM sleep deprivation (Mark, Heiner, Mandel and Godin, 1969) and REM sleep rebound following 91 h of deprivation (Pujol, Mouret and Glowinski, 1968). Because tyrosine is thought to be the rate‐limiting enzyme (Udenfriend, 1966) in the synthetic pathways for norepinephrine and since the above‐mentioned studies are suggestive of changes in the activity of the enzyme, we decided to measure tyrosine hydroxylase activity following REM sleep deprivation.
Desmosterol levels in human foetal brain—a reassessment
Authors: Dennick R. G. , Dean P. D. G. , Abramovich D. A.
Published: October 2006

Cholesterol, an essential component of the central myelin sheath, is synthesized in large quantities during myelination in the central nervous system. However, in rat brain prior to and during the early stages of myelination desmosterol accumulates in significant amounts (Fumagalli and Paoletti, 1963; Kritchevsky and Holmes, 1962)
Developmental changes of cholesterol ester hydrolases localized in myelin and microsomes of rat brain1
Authors: Eto Y. , Suzijki K.
Published: October 2006

We Previously demonstrated two distinct cholesterol ester hydrolases in rat brain (Eto and Suzuki, 1971). One of the two hydrolases had a pH optimum of 6·6 and showed a bimodal subcellular distribution, in microsomes and myelin. A substantial activity of this enzyme was present in newborn rat brain. The activity remained relatively unchanged during the first 12 days and then increased sharply, concomitant with the period of active myelination (Eto and Suzuki, 1972a). The more recent investigation, however, clearly demonstrated that this pH 6·6 cholesterol ester hydrolase actually consists of two distinct cholesterol ester hydrolases, one primarily localized in microsomes and the other almost exclusively localized in the myelin sheath (Eto and Suzuki, 1972b, 1973). The microsomal hydrolase had a pH optimum of 6·0 and was activated by sodium taurocholate and Triton X‐100, particularly by the latter. The myelin enzyme had a pH optimum of 7·2. It was activated by sodium taurocholate but slightly inhibited by Triton X‐100. These new findings suggested that the previously reported developmental curve of the pH 6·6 cholesterol ester hydrolase was probably a composite of developmental changes of these two distinct cholesterol ester hydrolases. We report here the findings which confirm the above prediction and update the information regarding the developmental changes of the enzymes involved in cholesterol ester metabolism in rat brain.
On the loss of gangliosides by dialysis
Authors: Kanfer J. N. , Spielvogel Christine
Published: October 2006

The Gangliosides represent a family of sialic acidcontaining sphingoglycolipids which have ceramide (N‐acyl‐sphingosine) as the basic hydrophobic portion (Svennerholm, 1972). A heteropolysaccharide is glycosidically linked through the primary hydroxyl group of ceramide and the aldehyde of glucose. There are usually three or four different carbohydrates and up to a total of seven in the chain. The isolated gangliosides are soluble both in organic and aqueous solvents presumably because of their content of both hydrophobic and hydrophilic groups. The most commonly employed extraction procedure is based upon their solubility in chloroform‐methanol (2: 1, v/v) and subsequent partitioning into an aqueous methanol phase (FOLCH, LEES and SLOANE‐STANLEY, 1957). This methanolic solution is then dialysed against water to remove small molecular‐weight contaminants. This paper reports the loss of gangliosides upon dialysis when they are present at low concentrations.

Gangliosides were prepared from fresh calf brain as previously described (Kanfer, 1969) and contained 25‐25% GMl, as judged by quantitative thin‐layer chromatography (Suzuki, 1964). GM2 was prepared from this material by treatment with neuraminidase as previously described (Kolodny, Brady, Quirk and Kanfer, 1970) and purified by the procedure of Winterbourne (1971). GM2 was isolated from brain tissue of a Tay‐Sachs child provided by Dr. B. Volk. Thin‐layer chromatography was carried out on Analtech Silica Gel G plates (Analtech Co., Wilmington, Del.) with chloroformmethanol‐2.5 N NH4OH (60 : 30 : 8, by vol.) as developing solvent. Total sialic acid was quantified by the resorcinol procedure according to Suzuki (1964). Duplicate known quantities of gangliosides were dissolved in 2 ml of methanol 41 M KCI(1 : 1, v/v) and dialysed overnight in untreated Visking tubing (0.22‐in. dia.; Fisher Scientific Co., Pittsburgh, Pa.; Cat. No. 1000) against a 500‐fold vol. of distilled water at 4°C. The contents of the sacs were removed and the total volume was measured; a 10‐1 5 per cent increase in volume was usually observed. Portions were analysed in duplicate for total sialic acid content, and the remainder was lyophilized for examination by TLC.
PROTEIN SYNTHESIS BY HIGHLY AGGREGATED AND PURIFIED POLYSOMES FROM YOUNG AND ADULT RAT BRAIN
Authors: Fellous Arlette , Francon J. , Nunez J. , Sokolof L.
Published: October 2006

The state of aggregation and the activity of polyribosomes as well as the activity of the pH 5 enzyme fraction were studied at two stages of postnatal brain development, 9 and 50 days after birth. When the polyribosomes were prepared at 0°C in the presence of 5 mm‐Mg2+, more than 85 per cent of the polyribosome material exhibited a sedimentation coefficient higher than 110 S. High Mg2+ concentrations are, therefore, unnecessary to obtain highly aggregated brain polyribosomes. The basal amino acid incorporating activity of both 9‐ and 50‐day‐old rat brain preparations is at least equal to that of rat liver. When prepared by the same procedure as above, 9‐day‐old rat brain polyribosomes seem to be more active (20 per cent) than those of adult brain. However, this difference in activity depends on the presence of a non‐ribosomal inactive contaminant which is always present in higher amounts in adult brain preparations. When purified from this contaminant, the preparations do not differ in activity. High Mg2+ concentrations are also not necessary for optimal protein synthetic activity and, in fact, are inhibitory. When assayed with both types of highly aggregated polyribosomes, the pH 5 enzyme fraction from adult brain is clearly less active than that of 9‐day‐old rats.

These results suggest that the loss of brain protein synthesis during development does not depend on the stability of the messenger RNA‐ribosome complex but only on the soluble pH 5 enzyme fraction.
Accumulation of adenosine 3′,5′‐monophosphate in incubated slices from discrete regions of squirrel monkey cerebral cortex: effect of norepinephrine, serotonin and adenosine
Authors: Skolnick P. , Huang M. , Daly J. , Hoffer B.
Published: October 2006

THE ROLE of adenosine 3′5′‐monophosphate (cyclic AMP) in the central nervous system is as yet unknown. However, a variety of putative neurotransmitters such as norepinephrine, serotonin and histamine have been found to elicit enhanced accumulations of cyclic AMP in cerebral cortical slices from a variety of species (SHIMIZU and DALY, 1972; FORN and KRISHNA, 1971; SHIMIZU, TANAKA, SUZUKI and MATSUKADO, 1971; FUMAGALLI, BERNAREGGI, BERTI and TRABUCCHI, 1971). In addition, depolarization of membranes in cortical slices elicits a marked accumulation of cyclic AMP, probably mediated through the action of adenosine (KAKIUCHI, RALL and MCILWAIN, 1969; SHIMIZU. CREVELING and DALY, 1970). These results, obtained with grey matter from the entire cerebral cortex, suggest an intimate relationship between neuronal activity, release of putative neurotransmitters, and enhanced accumulation of cyclic AMP in brain tissue. Since innervation and electrical activity in the cerebral cortex differs among functionally distinct neocortical areas and in the histologically distinct limbic cortex, it appeared possible that these differences would also be manifest in the regional control of cyclic AMP levels. We now report that the response of the cyclic AMP generating system to putative neurotransmitters and adenosine does differ among discrete functional regions of the squirrel monkey cerebral cortex.