bluuebunny/crossref_metadata_2025 huggingface dataset:
STUDIES ON THE METABOLIC DETERMINANTS OF D‐GALACTOSE‐INDUCED NEUROTOXICITY IN THE CHICK1
Authors: Kozak L. P. , Wells W. W.
Published: October 2006

The contents of galactose, galactitol, galactose 1‐phosphate, UDP‐galactose and UDP‐glucose in the brains of chicks fed a diet containing 40 % (w/w) D‐galactose were determined at regular intervals during a 48 h period which terminated in convulsive activity and death of the animals. Although levels of galactose and galactitol were markedly elevated, UDP‐galactose and UDP‐glucose levels were not significantly increased. The level of galactose 1‐phosphate rose to 1‐3 μg/g of fresh tissue by 14 h but gradually diminished until, at 48 h, the content was 0‐25 μg/g. The metabolic turnover of these compounds, as shown by labelling experiments with inorganic [32P]phosphate and [U‐14C]galactose, indicated that galactose 1‐phosphate and UDP‐galactose were rapidly metabolized, yet relatively little galactose was utilized by the brain as a source of energy. These observations have prompted us to propose a mechanism for the turnover of galactose 1‐phosphate that involves cyclical phosphorylation and dephosphorylation reactions in the brains of galactose‐fed chicks. In support of this hypothesis, we have identified phosphatase activity which has a relatively low Km value for galactose 1‐phosphate (0‐06‐0‐07 mM) in virtually all subcellular fractions of homogenates of chick brain. Maximum activity of the phosphatase is several‐fold greater than that recorded for galactokinase (EC 2.7.1.6) and galactose 1‐phosphate uridyltransferase (EC 2.7.710) from chicken brain.
COMPOSITION OF GANGLIOSIDES AND PHOSPHOLIPIDS OF NEURONAL AND GLIAL CELL ENRICHED FRACTIONS1
Authors: Hamberger A. , Svennerholm L.
Published: October 2006

Abstract— Fractions enriched in neuronal cell bodies and in glial cells were isolated from rabbit cerebral cortex by discontinuous gradient centrifugation. The ratio of total lipid to protein was approx. 50 per cent higher in the glial fraction than in the neuronal fraction. The fatty acid composition for the major phosphoglycerides was with few exceptions, similar for neurons and glia. The ganglioside concentration was very low for both cell types, but was approx. twice as high in the glial cells as in the neurons. The pattern of individual gangliosides was, however, very similar for the glial and neuronal fractions and did not differ from that of unfractionated cerebral cortex, synaptosomes and mitochondria. The latter results are discussed in relation to the estimated amounts of plasma membrane in the neuronal and glial fractions.
THE 4‐O‐METHYL METABOLITES OF CATECHOLAMINES IN MAN: CHROMATOGRAPHIC IDENTIFICATION OF 3‐HYDROXY,4‐METHOXYPHENYLACETIC ACID (HOMO‐ISO‐VANILLIC ACID) IN CEREBROSPINAL FLUID
Authors: Mathieu P. , Revol L. , Trouillas P.
Published: October 2006

Abstract— The isomeric phenolic acids, homovanillic acid (4‐hydroxy,3‐methoxyphenylacetic acid) and homo‐iso‐vanillic acid (3‐hydroxy,4‐methoxyphenylacetic acid), were separated and identified by means of paper chromatography of their azo‐derivatives with diazotized para‐nitroaniline. Using this chromatographic procedure, homo‐iso‐vaniliic acid was identified in several samples of human cerebrospinal fluid, an observation which suggests that dopamine may be partly metabolized in brain, with the production of 4‐methoxy derivatives.
CHANGES IN GLUCOSE AND ENERGY METABOLISM IN VIVO IN DEVELOPING RETINAE FROM VISUALLY‐COMPETENT (DBA/1J) AND MUTANT (C3H/HeJ) MICE1
Authors: Lolley R. N.
Published: October 2006

Abstract— The distribution in vivo of glucose and lactate between the complete or sub‐ divided retina and the blood has been evaluated in DBA and C3H mice during postnatal development. Levels in vivo of several intermediates of glucose and energy metabolism were measured by enzyme‐linked fluorometric assays of freeze‐dried retinae; glucose and lactate were determined in freshly‐drawn plasma.

DBA retinae. During the first 20 days of postnatal life, the level of glucose in the plasma rose slightly while that in the retina declined: during this period the level of lactate in the plasma rose and became nearly equal to that in the retina. Changes during development in levels of glucose and glycogen were consistent with the interpretation that the rate of utilization of glucose in vivo is enhanced during early postnatal life.

C3H retinae. The levels of glucose and glycogen in vivo were abnormally high throughout the developmental period, whereas levels of lactate were normal. The rise in levels of glucose after the 15th postnatal day was not related to an increase in blood levels of glucose but rather to a decreased utilization of glucose during this period.

For the first 10 postnatal days the content of glucose, lactate, ATP and P‐creatine within the photoreceptor layer of C3H retinae were within normal limits. Then, biochemical changes occurred which were secondary to ultrastructural pathology in the photoreceptors. This observation suggested that glucose metabolism and energy production are not involved in the primary aetiology of the inherited disease.
CARBOHYDRATE‐PEPTIDE LINKAGES IN GLYCOPROTEINS AND MUCOPOLYSACCHARIDES FROM BRAIN
Authors: Margolis R. U. , Margolis R. K. , Atherton D. M.
Published: October 2006

Abstract— Treatment of glycopeptides, prepared from glycoproteins of rat and rabbit brain, with NaOH‐NaBH4 leads to the destruction of a portion of the serine, threonine and galactosamine present, and the appearance in acid hydrolysates of alanine, α‐aminobutyric acid and galactosaminitol. These results indicate that N‐acetylgalactosamine at the reducing end of oligosaccharide chains in brain glycoproteins is linked O‐glycosidically to the hydroxyl groups of serine and threonine residues. 2‐acetamido‐1‐(L‐β‐aspartamido)‐l,2‐dideoxy‐β‐D‐glucose was also detected after partial acid hydrolysis of the alkali‐stable glycopeptides, and most of the carbohydrate in brain glycoproteins appears to be linked by N‐acetylglucosaminylasparagine linkages. The results of the treatment of the sulphated mucopolysaccharides from bovine brain with alkaline‐borohydride indicate that the polysaccharide chains in chondroitin sulphate and heparan sulphate are linked exclusively to serine.
UPTAKE AND RELEASE OF TAURINE FROM RAT BRAIN SLICES
Authors: Kaczmarek L. K. , Davison A. N.
Published: October 2006

Abstract— Rapid efflux of [35S]taurine from rat brain slices was observed on electrical stimulation. Slower release resulted when the Ca2+ content of the perfusion medium was replaced with Mg2+. Uptake of [35S]taurine into rat cortical slices was unaffected by GABA, glutamic acid, glycine and leucine but was inhibited by alanine, ouabain, KCN and 2,4‐dinitrophenol. Of a number of analogues of taurine, 2‐aminoethylsulphinic acid was the most potent in inhibiting the uptake of [35S]taurine. The rate of uptake was found to be decreased by lowering the incubation temperature. The possibility that taurine may be a neurotransmitter is discussed.
REGIONAL AND SUBCELLULAR DISTRIBUTION OF AMINOTRANSFERASES IN RAT BRAIN
Authors: Benuck M. , Stern F. , Lajtha A.
Published: October 2006

Abstract— Aminotransferase activity was measured in various areas of the nervous system of the rat (cortical grey matter, midbrain, corpus callosum, spinal cord and sciatic nerve) and in subcellular fractions of rat brain (nuclei, mitochondria and cytosol). Activity was low or absent in the sciatic nerve relative to that in the other areas, with the exception of incubation of glutamate with oxaloacetate (25 per cent of the activity found in brain) and of asparagine with 2‐oxoglutarate (65 per cent of the activity found in brain). The distribution of enzymic activity was not homogeneous; alanine‐2‐oxoglutarate aminotransferase was highest in cortical grey matter; leucine‐ and GABA‐2‐oxoglutarate aminotransferases were highest in midbrain. Incubation of phenylalanine or tyrosine with 2‐oxoglutarate gave similar activities in grey matter and midbrain. Activity generally was higher in the grey matter than in corpus callosum or spinal cord. However, incubations of methionine with 2‐oxoglutarate, or glutamine with glyoxylate, gave similar activities in the three areas studied from the brain, whereas incubations of glutamate with glyoxylate gave highest activity in the corpus callosum. Only incubations of asparagine with 2‐oxoglutarate, and glutamate with glyoxylate, gave significant activity in the nuclear subcellular fraction. Aminotransferase activity of phenylalanine, tyrosine or GABA with 2‐oxoglutarate, or ornithine or glutamine with glyoxylate, was localized to mitochondria. The remaining reactions studied (glutamate with oxaloacetate; leucine, alanine, methionine or asparagine with 2‐oxoglutarate and glutamate with glyoxylate) demonstrated activity in both the mitochondrial fraction and the soluble supernatant fraction.
TYROSINE HYDROXYLASE IN RAT BRAIN: DEVELOPMENTAL CHARACTERISTICS
Authors: Coyle J. T. , Axelrod J.
Published: October 2006

Abstract— The development of tyrosine hydroxylase (tyrosine 3‐hydroxylase, EC 1.14.3.a) activity has been examined in whole rat brain and in various regions and subcellular fractions thereof. The specific activity of tyrosine hydroxylase increased almost 15‐fold from 15 days of gestation to adulthood. With maturation, those regions of the brain that contain only terminals of the catecholaminergic neurons showed the greatest increases in enzyme activity. There was a shift in the subcellular distribution of tyrosine hydroxylase from the soluble fraction in the fetal brain to the synaptosomal fraction in the adult brain. Tyrosine hydroxylase, dopamine hydroxylase (EC 1.14.2.1) and the specific uptake mechanism for norepinephrine appear to develop in a coordinated fashion.
CHANGES IN THE LACTATE AND MALATE DEHYDROGENASE ISOENZYME PATTERNS OF CHICKEN EMBRYO BRAIN AND RETINA
Authors: Pasantes‐Morales H. , Klethi J. , Urban P. F. , Mandel P.
Published: October 2006

Abstract— Lactate dehydrogenase and malate dehydrogenase isoenzyme patterns of chicken brain and retina have been investigated by cellulose acetate electrophoresis, during embryonic and post‐hatching development. The proportion of M‐type lactate dehydrogenase subunits decreases significantly in brain and retina with development. A marked increase in the H‐type subunits is observed in retina. Lactate dehydrogenase isoenzyme distribution appears to change in both organs in parallel with the metabolic changes of differentiation.

Malate dehydrogenase isoenzyme patterns do not reveal any consistent change of the ratio between the mitochondrial and cytoplasmic forms.
STUDIES ON THE SITE OF MEDIATED TRANSPORT OF CHLORIDE FROM BLOOD INTO CEREBROSPINAL FLUID: EFFECTS OF ACETAZOLAMIDE
Authors: Bourke R. S. , Nelson K. M.
Published: October 2006

Abstract— In monkeys we measured the steady‐state concentrations of Cl− in endogenous CSF, in artificial CSF (which had equilibrated with the underlying exposed surface of the cerebral cortex but was not in diffusion equilibrium with endogenous CSF), and in arterial plasma. The ratio of the distribution of Cl− in artificial CSF to that in plasma was consistent with a passive Donnan distribution, whereas that ratio describing Cl− levels in endogenous CSF in comparison to those in plasma clearly exceeded theratio required for a passive, Donnan−type of distribution for Cl−. The kinetic analysis of the efflux of Cl− from blood into endogenous CSF and into artificial CSF (perfused over the exposed surface of the cerebral cortex) indicated that the rate of efflux of Cl− into endogenous CSF which was continuous with ventricular fluid was inhibited by acetazolamide [in confirmation of a similar finding described previously by Maren and Broder (1970)], whereas the rate of efflux of chloride from blood into the artificial CSF perfusate was uninfluenced by pretreatment of animals with acetazolamide. We have discussed the site of mediated (active) transport of chloride from blood into CSF in light of these findings.
PROPERTIES OF MONOAMINE OXIDASES IN SYMPATHETIC NERVE AND PINEAL GLAND
Authors: Yang H.‐Y. T. , Goridis C. , Neff N. H.
Published: October 2006

Abstract— The monoamine oxidases (MAO) of rat pineal gland and superior cervical ganglion were compared and found to have different characteristics. The predominant enzyme in the ganglion was inhibited by low concentrations of clorgyline (0.1 μM), exhibited a lower apparent Km for tyramine than the enzyme in the pineal, was readily inactivated by trypsin, and was relatively heat‐stable. In contrast, the MAO of the pineal was inhibited by 0.1 mm clorgyline, was not readily inactivated by trypsin, and was heat‐labile. Moreover, these enzymes appeared to have different substrate specificities. Our results are consistent with the view that there may be multiple forms of MAO and that these forms may be associated with specific cell types.
CALCIUM‐BINDING PHOSPHOPROTEIN OF PIG BRAIN: EFFECTS OF CATIONS ON THE CALCIUM BINDING
Authors: Wolff D. J. , Huebner J. A. , Siegel F. L.
Published: October 2006

—The effects of various cations on the calcium‐binding properties of a brain phosphoprotein have been investigated employing an ultrafiltration binding assay. Sodium, magnesium, barium, strontium and manganese ions were competitive inhibitors of the calcium binding, and their affinity for the calcium‐binding site increased in the order given. Potassium was a non‐competitive inhibitor. Lanthanum, lead, mercuric and cadmium ions precipitated the phosphoprotein from solution. These findings are discussed in relation to a postulated role for the protein as a calcium‐receptor molecule involved in release of neurotransmitters.
THE REGIONAL AND SUBCELLULAR DISTRIBUTION OF CATECHOL‐O‐METHYL TRANSFERASE IN THE RAT BRAIN
Authors: Broch O. J. , Fonnum F.
Published: October 2006

Catechol‐O‐methyl transferase (COMT) activities determined in different regions of rat brain showed small variations. Highest activities were found in the hypothalamus and corpora quadrigemina, and lowest activities in the hippocampus and corpus striatum. The regional distribution of COMT was thus at variance with the distribution of DOPA decar‐ boxylase in this study and with the distribution of catecholamines and tyrosine hydroxylase reported in the literature. Determinations of the subcellular distribution of COMT in rat forebrain showed that 50 per cent of the activity was recovered in the high speed supernatant fluid and about 33 per cent in the crude mitochondrial fraction. Further separation of the latter by discontinuous sucrose gradients showed that the particulate COMT was found in the synaptosomal fraction in an occluded form. Full enzyme activity was only obtained after treatment with a detergent or after resuspension in water. After hypo‐osmotic rupture of the crude mitochondrial fraction, COMT was recovered in the cytoplasmic fraction. The subcellular distribution of COMT was very similar to the ones of lactate dehydrogenase and DOPA decarboxylase.

The proportions of soluble COMT obtained from homogenates of various regions of the brain differed from that of choline acetyl transferase and DOPA decarboxylase but were similar to that of lactate dehydrogenase. In conclusion, COMT is a cytoplasmic enzyme almost evenly distributed in the CNS. Its distribution does not resemble the distributions of the catecholamines or of the enzymes participating in the synthesis of catecholamines.
EFFECTS OF SODIUM FLUOROACETATE ON THE METABOLISM OF N‐ACETYLASPARTATE AND ASPARTATE IN MOUSE BRAIN
Authors: Nadler J. V. , Horwitch P. , Cooper J. R.
Published: October 2006

A subconvulsant dose of sodium fluoroacetate inhibited the metabolic utilization of intracerebrally‐administered N‐acetyl‐l‐[U‐14C]asparticacid and the labelling of glutamine from this precursor in mouse brain, but not the labelling of glutamate or aspartate. A convulsant dose also inhibited the utilization of l‐[U‐14C]aspartic acid. When intraperitoneal injection of a convulsant dose of sodium fluoroacetate was followed by intracerebral injection of N‐acetyl‐l‐[U‐14C]asparticacid, the levels of N‐acetylaspartate, aspartate and glutamate in brain were lowered, while the glutamine content was increased. The specific radioactivity of glutamine relative to that of glutamate was much lower when these compounds were labelled from l‐[U‐14C]aspartic acid than when N‐acetyl‐l‐[U‐14C]aspartic acid was used as the precursor. Intracerebral injection of tracer amounts of l‐[U‐14C]aspartic acid reduced the content of N‐acetylaspartate in brain and raised the glutamine content. Sodium fluoroacetate had no additional effect on the relative specific radioactivity of glutamine or the content of N‐acetylaspartate, aspartate, glutamate or glutamine when l‐[U‐14C]aspartic acid was the precursor. We consider the results to be consistent with a selective inhibition both by sodium fluoroacetate and by exogenous aspartic acid of the tricarboxylic acid cycle in brain associated with the biosynthesis of glutamine. We suggest that the activity of this pathway may regulate the metabolism of N‐acetylaspartate and aspartate.
IMIPRAMINE‐INDUCED CHANGES OF BRAIN ADENOSINE TRIPHOSPHATASE ACTIVITY
Authors: Nag D. , Ghosh J. J.
Published: October 2006

Abstract— Adenosine triphosphatase (ATPase) activities of brain microsomal and synaptosomal preparations are inhibited by imipramine [5‐(3′‐dimethylamino propyl)‐10, 11‐dihy‐dro‐5H‐dibenz (b,f) azepine] in vitro, whereas microsomal ATPase activity is stimulated and synaptosomal ATPase activity remains unaltered under in vivo imipramine treatment. The inhibition of ATPase activity can to some extent be counteracted by spermine [N, N′‐bis(3 aminopropyl)‐1,4‐butanediamine]. Determination of Km values from double reciprocal plots (activity‐1 vs. ATP mM‐1) under drug and spermine‐treated conditions appear to indicate that spermine can to some extent imparta stabilizing effect mainly on the microsomal membrane ATPase, preventing inhibition in presence of imipramine in vitro, although spermine has no effect on the already destabilized membrane ATPase. Spermine exerts a stabilizing effect on membrane ATPase possibly by increasing the affinity of the enzyme for the substrate.
Isolation and characterization of phenylethylamine and phenylethanolamine from human brain
Authors: Inwang E. E. , Mosnaim A. D. , Sabelli H. C.
Published: October 2006

The Presence of endogenous 2‐phenylethylamine in mammalian tissues has long been suspected, in view of the fact that L‐phenylanine, a substrate for L‐aromatic amino acid decarboxylase (Lovenberg, Weissbach and Udenfriend, 1962), is found in substantial amounts in many neural and non‐neural tissues. It has been difficult to demonstrate the presence of phenylethylamine in tissues of untreated animals because this amine is an excellent substrate for monoamine oxidase (Mantegazza and Riva, 1963). Using paper chromatography and electrophoresis, Nakajima, Kakimoto and Sano (1964) tentatively identified phenylethylamine in many organs of animals pretreated with monoamine oxidase inhibitors. Phenylethylamine exerts, in animals pretreated with such inhibitors, behavioural stimulant effects similar to those induced by amphetamine (Mantegazza and Riva, 1963). These effects may in part be attributable to catecholamine release (Fuxe, Grobecker and Jonsson, 1967) and partly to a direct effect exerted by phenylethylamine itself (Fischer, Ludmer and Sabelli, 1967; Giardina, Pedemonte and Sabelli, 1972). The brain content of phenylethylamine in mice (Mosnaim and Sabelli, 1971), rabbits (Sabelli, Giardina, Mosnaim and Inwang, 1972) and rats (Fischer, Spatz, Heller and Reggiani, 1972) is increased by antidepressive treatments (imipramine, monoamine oxidase inhibitors, electroshock) and reduced by reserpine. The urinary excretion of phenylethylamine is decreased in depressed patients (Fischer, Heller and Miró, 1968; Boulton and Milward, 1971; Inwang, Sugerman, Mosnaim and Sabelli, 1972; Fischeret al., 1972).

However, the presence of phenylethylamine in brain has not yet been conclusively demonstrated because the analytical procedures used in the above‐mentioned investigations were not sufficiently specific. In the present study we isolated and identified, by a number of analytical procedures, phenylethylamine and its metabolite 2‐hydroxy‐2‐phenylethylamine (phenylethanolamine) from human brain. Molinoff, Landsberg and Axelrod (1969) have shown by enzymatic methods the formation of phenylethanolamine following the administration of phenylethylamine.
Effect of growth hormone on glycogenesis in cerebral cortical slices
Authors: Visweswaran P. , Subrahmanyam K.
Published: October 2006

The uptake of glucose by cerebral cortical slices of rats was found to be enhanced by insulin by Rafaelsen (1961) and Genes and Charnaya (1966). This was confirmed by Prasannan and Subrah‐manyam (1965) and more recently by Nelson, Schultz, Pasoneau and Wry (1968). Eisenberg and Seltzer (1962) and Gotistein, Held, Sebenng and Walpurger (1965) obtained evidence for a direct effect of insulin on the entry of glucose into brain and on its metabolism in this tissue. A marked resynthesis of glycogen was demonstrated with glucose as substrate by Lebaron (1955) and Mcilwain and Tresize (1956) in cerebral cortical slices of the guinea pig. Prasannan and Subrahmanyam (1965) obtained evidence for a similar resynthesis of glycogen in cerebral cortical slices of the rat. Addition of 0.2 unit of insulin per 3.5 ml of incubating medium gave rise to an increase of 60 per cent in the resynthesis of glycogen in these slices. The incorporation of 14C from labelled glucose into glycogen and CO2 by cerebral cortical slices of normal and alloxan diabetic rats and the stimulation of the incorporation into glycogen by insulin in vitro was reported by Visweswaran, Prasannan and Subrahmanyam (1969). An insulin‐like action of growth hormone on the carbohydrate metabolism was reported by Ketterer, Randle and Young (1967) and Manchester and Young (1961). It was believed to be due to the formation of a polypeptide breakdown product of growth hormone which has biological insulin‐like properties. Park, Brown, Cornbluth, Daughaday and Krahl. (1952) reported an increased uptake of glucose by isolated rat diaphragm due to the action of growth hormone which is similar to that of insulin. Hence, it was considered appropriate to study the incorporation of 14C from labelled glucose into glycogen and CO2 by cerebral slices of growth hormone treated rats and the effect of growth hormone treatment on the activities of the enzymes concerned with glycogenesis in rat cerebral cortex.
ISOLATION AND CHARACTERIZATION OF AN ORGAN SPECIFIC RIBONUCLEOPROTEIN FROM GOAT BRAIN
Authors: Sharma N. C. , Talwar G. P.
Published: October 2006

An organ specific protein (NP) has been isolated from the goat brain by salt fractionation and preparative polyacrylamide gel electrophoresis. The antiserum against this protein gave immunological cross reaction with the brain extracts of a wide variety of animals but did not react with extracts of liver, lung, kidney, spleen, heart and blood. Similar proteins have also been found to be present in monkey brain and human astrocytomas in culture. Evidence is presented to show that it is a ribonucleoprotein. This is based on the following observations: (1) its absorption characteristics before and after RNase treatment, (2) chemical analysis showing the presence of ribose, purines and pyrimidines, (3) incorporation of radioactive uridine and lysine in monkey brain and in human astrocytomas in culture into a protein band having electrophoretic mobility and immunological characteristics analogous to NP protein.

The molecular weight of the NP protein has been found to be 25,120 Daltons, while the residual moiety after treatment with RNase has a molecular weight of 19,060. The RNA content of NP protein in four separate preparations was 20.65% (±0.55 S.D.) as determined by the orcinol colour reaction and 23.85% (± 0.88 S.D.) gauged by the ratio of extinctions at 260 and 280 nm. The base composition of RNA has also been determined. The nature of association of the RNA moiety with the protein is not known. The two are, however, not dissociable by SDS and high pH excluding the possibility of aminoacyl linkage and nonspecific adsorption.
PLASMA AND BRAIN TRYPTOPHAN CHANGES IN EXPERIMENTAL ACUTE HEPATIC FAILURE
Authors: Curzon G. , Kantamanem B. D. , Winch J. , Rojas‐Bueno A. , Murray‐Lyon I. M. , Williams R.
Published: October 2006

An experimental model for acute hepatic failure in man was obtained in pigs by hepatic devascularization. After operation, liver function was grossly impaired, movements became inco‐ordinated and coma ensued. Most animals died 5½–8½ h after operation. Plasma unesteritied fatty acid and free (but not total) tryptophan concentrations rose markedly after operation and correlated significantly with each other. Brain tryptophan concentration increased and correlated significantly with plasma free tryptophan concentration. Increased tryptophan was found in the four brain regions studied (hypothalamus, thalamus, caudate and cortex) and was associated with raised 5‐hydroxytryptamine turnover as indicated by raised 5‐hydroxyindolylacetic acid concentration. Results are discussed in relation to altered tryptophan metabolism in human hepatic coma and to investigations of the influence of plasma unesterified fatty acid and free tryptophan changes on brain tryptophan metabolism in the rat.
Effect of intraventricular injection of 5,7‐dihydroxytryptamine on regional tryptophan hydroxylase of rat brain
Authors: Baumgarten H. G. , Victor S. J. , Lovenberg W.
Published: October 2006

5,6‐DIHYDROXYTRYPTAMINE has been shown to cause selective degeneration of serotonergic neurons in the central nervous sytem (BAUMGARTEN, LACHENMAYER and SCHLOSSBERGER, 1972b). This degeneration is accompanied by depletion of serotonin (BAUMGARTEN et al., 1971; 1972a) and loss of tryptophan hydroxylase activity (VICTOR, BAUMGARTEN and LOVENBERG, 1973) in certain regions of the brain. In the current experiments, the effect of 5,7‐dihydroxytryptamine (another dihydroxylated tryptamine derivative) on tryptophan hydroxylase activity has been examined. Since tryptophan hydroxylase is the rate‐limiting enzyme in serotonin biosynthesis and has a similar distribution to that of serotonin in the brain, it is used as a biochemical marker of serotonergic neurons, Recent experiments also indicate that 5,7‐dihydroxytryptamine causes morphological damage to serotonergic neurons of the central nervous system (BAUMGARTEN and LACHENMAYER, 1972).
PARTIAL PURIFICATION AND PROPERTIES OF CHOLINE KINASE (EC 2.7.1.32) FROM RABBIT BRAIN: MEASUREMENT OF ACETYLCHOLINE
Authors: Haubrich D. R.
Published: October 2006

Choline kinase (EC 2.7.1.32; ATP: choline phosphotransferase) was purified 200‐fold from an extract of acetone powder of rabbit brain by a combination of acid precipitation, ammonium sulphate precipitation, DEAE cellulose chromatography, and ultrafiltration. Maximal activity of 243 nmol of phosphorylcholine synthesized. min−1 mg−l of protein occurred at pH 9.5–10.0 in the presence of 10 mm MgS04, 10 mm choline and 0.005% (w/v) bovine serum albumin. 2‐Aminoethanol, 2‐methylaminoethanol, and 2‐dimethylaminoethanol were also phosphorlyated by the enzyme preparation. The enzyme quantitatively converted low concentrations of choline (2.5–50 μm) to phosphorylcholine [32P] in the presence of ATP [y32P], and may, therefore, be used to measure small amounts of choline acetylcholine. There were two Km values for choline at pH 9.5; 32 μm and 0.31 mm. At pH 7.4, the higher Km was not observed and enzyme activity was maximal with 0.1 mm choline. The Km for ATP was 1.1 mm. Enzyme activity was inhibited by ATP (20 mm), AMP, ADP, cytidine diphosphocholine (1 or 10 mm), and activated by choline esters (1.0 mm), NaCl or KCl(200 mm).
STUDIES ON THE MECHANISM OF DEMYELINATION: TRIETHYL TIN‐INDUCED DEMYELINATION
Authors: Smith Marion Edmonds
Published: October 2006

The metabolism of myelin undergoing breakdown as a result of edema induced by chronic administration of triethyl tin (TET) dissolved in the drinking water (10 mg/l.) was examined. The spinal cord showed more edema and loss of myelin than the brain. Uptake in vitro of [1‐14C]acetate into myelin lipids of slices of brain or spinal cord from TET‐treated rats was depressed until 4–5 weeks after the beginning of the regime, then rose to above normal levels. The uptake of [l‐14C]leucine into myelin protein rose within several weeks of TET treatment to levels averaging over 300 per cent of normal and remained high even after the TET was removed. The high levels of [l‐14C]leucine incorporation were inhibited by cycloheximide and were not explained by an increase in the size of the free amino acid pool. The three classes of myelin proteins, basic, proteolipid protein, and Wolfgram protein shared in the increased incorporation. Spinal cord myelin showed the greatest metabolic response, brain stem myelin less, and myelin from the forebrain was minimally affected by the TET treatment. Myelin prelabelled by intracisternal injection of [l‐14C]acetate and [l‐14C]leucine before the onset of TET administration showed faster turnover in myelin proteins in relation to the myelin lipids than the control in the most severely affected animals, but not in others less affected. A ‘floating fraction’ was observed floating on 10.5% (w/v) sucrose during the myelin purification. This fraction showed metabolic characteristics typical of myelin, and myelin‐labelling studies at various stages of the animal's development showed it to be derived from recently synthesized myelin. The floating fraction from the brain contained less cerebroside and more lecithin than myelin, while the spinal cord floating fraction composition was much like that of myelin. The floating fractions contained less protein typical of myelin (basic and proteolipid protein) and more highmolecular‐weight protein which may have been derived from contaminating microsomes. The floating fraction was presumed to be partially deproteinated myelin. The use of TET‐treatment as model for demyelination as a result of edema and proceeding in the absence of macrophages is discussed.
AXOPLASMIC TRANSPORT OF DOPAMINE IN NIGRO‐STRIATAL NEURONS1
Authors: Fibiger H. C. , McGeer E. G. , Atmadja S.
Published: October 2006

The possibility that dopamine is transported in the nigro‐striatal system was investigated by the stereotaxic injection of labelled tyrosine or l‐DOPA into the substantia nigra of tranylcypromine‐pretreated rats. At various intervals thereafter (2‐48 h), significant quantities of labelled material were recovered from the ipsilateral substantia nigra, globus pallidus and caudate‐putamen, The activity in the substantia nigra consisted of DOPA, dopamine, methoxytyramine, acid metabolites and other unidentified metabolites. In the caudate‐putamen, however, nearly all of the activity (85 per cent) was recovered in the dopamine fraction, the remainder being distributed among some of the metabolites. No DOPA was recovered from the caudate‐putamen. On the basis of time‐course studies after the injection of [14C]DOPA into the substantia nigra, we calculated the transport rate of dopamine in the nigro‐striatal bundle to be 0.8 mm/h. Electrolytic lesions of the nigrostriatal bundle at the level of the lateral hypothalamus, pretreatment with 6‐hydroxydopamine, or injections of [14C]DOPA dorsal to the substantia nigra each produced profound reductions in the amount of activity subsequently recovered from the caudate‐putamen. These data suggest that the activity recovered from the caudate‐putamen after injections of [14C]DOPA into the or substantia nigra reflected axonal transport rather than other processes such as diffusion or transport via the circulation. Pretreatment with the DOPA decarboxy‐lase inhibitor, Ro 4‐4602, significantly reduced the amount of activity recovered in the caudate‐putamen, an indication that decarboxylation of DOPA to dopamine was a prerequisite for transport. Pretreatment with reserpine also severely reduced the transport of dopamine in the nigro‐striatal bundle, an observation suggesting that dopamine was transported by binding to the amine storage granules. There was no evidence of retrograde transport of dopamine in the nigrostriatal bundle. Injections of larger than tracer quantities of labelled tyrosine into the substantia nigra did not produce the degree of transport of dopamine that was obtained after injections of DOPA, a result suggesting that the amine storage granules may not normally be filled during axonal transport.
BRAIN LIPIDS OF A CASE OF JUVENILE NIEMANN‐PICK DISEASE1
Authors: Tjiong H. B. , Seng P. N. , Debuch H. , Wiedemann H.‐R.
Published: October 2006

—Lipids of frontal lobe grey and white matter were examined in parallel from a normal and a diseased child (M. Niemann‐Pick), both nine years of age.

In the grey matter of the pathological case the following changes, although small, were found: a slight increase in all phospholipids and decreased values for nervonic acid in cerebrosides and for hydroxy fatty acids in sulphatides.

White matter seemed much more affected by the disease: water content was about 6 per cent higher which corresponds to an approx. 20 per cent loss of dry substance compared with the normal brain. Further increases were observed in ‘ganglioside’ fraction and in all phosphatides. Cerebroside and sulphatide levels appeared decreased owing to destruction of myelin. In all of the glycerophosphatides oleic acid portions were lowered whereas in sphingolipids mainly nervonic acid values were reduced. Aldehyde content of both tissues seemed lowered in the disease, however, changes in composition were observed only in white matter, where the stearaldehyde portion of ethanolamine glycerophospholipid increased at the expense of palmitaldehyde and oleinaldehyde.
THE KINETIC PROPERTIES OF HEXOSE TRANSPORT INTO SYNAPTOSOMES FROM GUINEA PIG CEREBRAL CORTEX
Authors: Heaton G. M. , Bachelard H. S.
Published: October 2006

Abstract— Hexose uptake into synaptosomes has been shown to occur by a saturable mechanism with a relatively small component due to passive diffusion. Competition between glucose and deoxyglucose for entry was demonstrated and the kinetic properties of the process were studied by using glucose as a competitive inhibitor of deoxyglucose entry. During kinetic analysis of the transport process higher affinities for both hexoses were indicated by the results from the synaptosome preparation compared with those from cerebral cortex slices. The kinetic properties of glucose inhibition of deoxyglucose uptake into synaptosomes could not be interpreted completely in terms of a unimolecular transport model. The results appear to follow predictions for ‘doubly competitive inhibition’, and some evidence for polyvalency of the uptake process was obtained.
EFFECT OF THIAMINE DEPRIVATION AND THIAMINE ANTAGONISTS ON THE LEVEL OF γ‐AMINOBUTYRIC ACID AND ON 2‐OXOGLUTARATE METABOLISM IN RAT BRAIN12
Authors: Gubler C. J. , Adams B. L. , Hammond B. , Yuan En Chuan , Guo Shirley M. , Bennion M.
Published: October 2006

Brain levels of y‐aminobutyric acid (GABA), glutamate and 2‐oxoglutarate, activities of glutamate decarboxylase GABA‐transaminase plus succinic semiaidehyde dehydrogenase and blood levels of glutamate and 2‐oxoglutarate were determined in normal, thiamine‐deprived, oxythiamine‐treated and pyrithiamine‐treated rats. Brain GABA levels were significantly reduced in thiamine‐deprived and pyrithiamine‐treated rats, but the activities of the enzymes of the GABA shunt pathway were not affected. Brain levels of glutamate were decreased and of 2‐oxoglutarate increased in all three types of deficiency. This was associated with similar decreases in glutamate and increases in 2‐oxoglutarate in the blood in all three deficient groups. Intraventricular injections of 2‐[U‐14C] oxoglutarate into the brain in these four groups of rats resulted in some significant differences in distribution of 14C in various TCA‐pathway intermediates and satellite compounds in the brain. Increases in 14C‐label were observed for glutamine and 2‐oxoglutarate in all three deficient groups as compared to controls. The 14C content of succinate, fumarate and aspartate was decreased in the thiamine deprived and PTh‐treated groups and [14C]glutamate was decreased in all three deficient groups. The 14C content of GABA was not significantly affected.
THE HALF‐LIFE OF ACETYLCHOLINESTERASE IN MATURE RAT BRAIN
Authors: Wenthold R. J. , Mahler H. R. , Moore W. J.
Published: October 2006

—The rate of degradation of acetylcholinesterase [EC 3.1.1.7] in mature rat cerebral cortex was determined from the time course of the label introduced into the protein by one intraventricular injection of l‐leucine‐l‐14C. The half life of the enzyme was 2.84 ± 013 days.
ÈVIDENCE FOR THE COMPARTMENTATION OF GLUTAMATE METABOLISM IN ISOLATED RAT RETINA
Authors: Starr M. S.
Published: October 2006

—Glucose is a major precursor of glutamate and related amino acids in the retina of adult rats. 14C from labelled glucose appears to gain access to a large glutamate pool, and the resulting specific activity of glutamate labelled from glucose is always higher than that of glutamine or the other amino acids.

Radioactive acetate appeared to label a small glutamate pool. The specific activity of glutamine labelled from acetate relative to that of glutamate was always greater than 1.0. Other precursors of the small glutamate pool were found to include glutamate, aspartate, GABA, serine, leucine and sodium bicarbonate.

The level of radioactivity present in retinae incubated with [U‐14C]glucose or [1‐14C]sodium acetate was reduced in the presence of 10−5m‐ouabain. Under these conditions, the relative specific activity of glutamine labelled from [1‐14C]sodium acetate was lowered, but it was raised when [U‐14C]glucose was used as substrate. Ouabain also considerably reduced the synthesis of GABA from [1‐14C]sodium acetate. In all cases ouabain caused a fall in the tissue levels of the amino acids.

Aminooxyacetic acid (10−4m) almost completely abolished the labelling of GABA from both [U‐14C]glucose and [1‐14C]sodium acetate, while the RSA of glutamine labelled from the latter substrate was significantly increased. Aminooxyacetic acid raised the tissue concentration of glutamate, but caused a fall in the tissue concentrations of glutamine, aspartate and GABA.

The results suggest that there are separate compartments for the metabolism of glutamate in retina and that these can be modified in different ways by different drugs.
CHANGES IN ENZYME PATTERNS PRODUCED BY HIGH POTASSIUM CONCENTRATION AND DIBUTYRYL CYCLIC AMP IN ORGAN CULTURES OF SYMPATHETIC GANGLIA1
Authors: Goodman R. , Oesch F. , Thoenen H.
Published: October 2006

—Preliminary experiments had shown that acetylcholine, the putative mediator of trans‐synaptic induction of tyrosine hydroxylase (TH) and dopamine β‐hydroxylase (DBH) in vivo, did not lead to an increase in these enzyme activities in mouse superior cervical ganglia kept in organ culture. It was the aim of the present study to evaluate whether increases in tyrosine hydroxylase and dopamine β‐hydroxylase evoked by other stimuli such as potassium or dibutyryl cyclic AMP in such an in vitro system are representative for in vivo trans‐synaptic induction where changes in the levels of enzymes involved in norepinephrine synthesis or degradation are strictly confined to TH and DBH. In the presence of elevated concentrations of potassium or 5 mm dibutyryl cyclic AMP under organ culture conditions TH and DBH as well as DOPA decarboxylase and monoamine oxidase were significantly (P < 0.025) increased. The increase in total activities of TH and DBH were completely, those of DOPA decarboxylase and monoamine oxidase partially, inhibited by cycloheximide.

In the presence of high concentrations of potassium, the total protein content of the ganglia was 28 per cent higher than in culture controls while dibutyryl cyclic AMP had no significant effect. Cycloheximide alone caused the protein content to fall to 70 per cent of that in control cultures. The loss of protein in the presence of cycloheximide was not accompanied by a simultaneous loss of TH, DOPA decarboxylase or monoamine oxidase, but DBH was decreased. Potassium was shown to increase the incorporation of [3H]leucine into TCA‐insoluble protein during an early culture period but dibutyryl cyclic AMP showed no such effect. An increase in the rate of incorporation of [3H]leucine into protein was seen in both the control and elevated potassium cultures after 48 h. This increase did not occur in the presence of dbcAMP.

The difference in enzyme patterns under conditions of elevated potassium and dibutyryl cyclic AMP and the fact that no changes in the levels of endogenous cyclic AMP were observed during exposure to 54 mm‐potassium for a time period sufficient to initiate changes ultimately leading to elevated TH levels argues against the mediation of the potassium‐induced enzyme increases by cAMP.

Since changes in enzyme patterns caused by potassium and dbcAMP were not similar to patterns seen in vivo under conditions of trans‐synaptic induction we conclude that use of this system as an in vitro model for in vivo trans‐synaptic induction necessitates great caution.
INCORPORATION OF 14C FROM [U‐14C]GLUCOSE INTO FREE AMINO ACIDS IN MOUSE BRAIN REGIONS UNDER CYANIDE INTOXICATION
Authors: Shimada M. , Kihara T. , Kurimoto K. , Watanabe M.
Published: October 2006

—During anoxia induced by the administration of potassium cyanide, [U‐14C]glucose was injected intraperitoneally into adult mice and they were decapitated at 5, 15 and 30 min after the injection. After freeze‐drying in vacuo, differences in the uptake of radioactive carbon from [U‐14C]glucose into free amino acids (glutamate + glutamine, aspartate + asparagine, GABA, alanine and glycine) in mouse cerebral neocortex, cerebellar hemisphere, caudate nucleus, thalamus, hypothalamus and medulla oblongata were investigated (by macroautoradiography and GLC separation) and compared with those obtained under normal conditions.

(1) During anoxia, autoradiographical densities in the thalamus and medulla oblongata were higher than that in the cerebral neocortex and caudate nucleus.

(2) Among specific radioactivities (d.p.m./μmol) of free amino acids, alanine gave the highest value during anoxia, except in the cerebellar hemisphere and hypothalamus at 5 min and the medulla oblongata at 30 min.

(3) During anoxia, the specific radioactivities of alanine and glycine in each brain region did not significantly decrease at 15 and 30 min compared with those under normal conditions. During anoxia, the specific radioactivity of glutamate + glutamine in the cerebellar hemisphere and hypothalamus did not significantly decrease compared with the normal conditions, while that of GABA, aspartate + asparagine and glutamate + glutamine in the cerebral neocortex, caudate nucleus, thalamus and medulla oblongata showed an increase.

(4) The percentage decrease of glutamate + glutamine and aspartate + asparagine at 5 and 15 min was highly significant in the cerebral neocortex and caudate nucleus.
DEVELOPMENTAL CHANGES IN GLYCOLYSIS IN RAT CEREBRAL CORTEX
Authors: Takagaki G.
Published: October 2006

Abstract— The ATP concentration in infant rat cerebral cortex slices which were incubated aerobically with glucose (5 mm) as substrate was much higher than in those from the adult. The higher ATP concentration in slices from young rat was also obtained when they were incubated aerobically with pyruvate (10 mm), dl‐lactate (20 mm) and dl‐3‐nydroxybutyrate (20 mm) However, when the slices were incubated anaerobically with glucose, the ATP concentration was very low. Thus, the formation of ATP in the slices from the young rat was thought to be mainly due to their oxidative metabolism, as in those from the adult. The amounts of glycolytic key enzymes in rat cerebral cortex (hexokinase. phosphofructokinase and pyruvate kinase) increased with age. Glycolysis was actually shown to be less active in the cerebral slices from young rats than from the adult. In addition it is known that the tricarboxylic acid cycle enzymes in rat cerebrum also increase with age. Consequently, the activity with respect to ATP formation must be lower in the cerebral cortex slices from young rats than from the adult. The fact that ATP was nevertheless higher in the slices from young rats may be explained by a lower rate of degradation. Developmental increases in the amounts of Na+‐K+‐ATPase and Mg2+ ‐ATPase in rat cerebral cortex were greater than those of the glycolytic key enzymes. These are discussed in relation to the observation that the rate of aerobic glycolysis in slices from cerebral cortex of young rats was not increased by d‐glutamate (5 mm) and high potassium (50 mm).
tRNA METHYLTRANSFERASE ACTIVITY IN NEONATAL AND MATURE MAMMALIAN NEURAL TISSUE
Authors: Johnson T. C. , Mathews R. A. , Chou L.
Published: October 2006

Abstract— The activity and kinetic characteristics of tRNA methyltransferases were measured with enzyme preparations obtained from neonatal and adult mouse brain tissue. Both neonatal and mature brain enzyme preparations were shown to contain a considerable amount of protein methylase activity which could interfere with the measurement of the tRNA methyltransferases. When increasing amounts of the unfractionated enzymes from young and adult neural tissue were added to reaction mixtures, the saturation kinetics were found to be considerably different. However, fractionation of the samples by precipitation at pH 5 resulted in an increase in the enzyme activity of preparations obtained from adult brain. Although the precipitation at pH 5 allowed a quantitative recovery of the enzyme activity of immature brain samples, this partial purification step led to an apparent activation of the tRNA methyltransferases in adult preparations. This activation was shown to be independent of differential changes in the thermolability of the enzymes but rather to be associated with an increase in the sites methylated and the measured affinity of the adult enzyme preparations with the tRNA substrate. Nicotinamide, a potent inhibitor of tRNA methyltransferase activity in other tissues, was shown to be ineffective in modulating brain tRNA methyltransferase activity. The results are discussed in light of the possible modulation of the activity of specific enzyme species and the alterations in the synthesis of nucleic acid precursors during neural development.
EVIDENCE FOR CALCIUM‐SENSITIVE COMPONENT IN BRAIN ACTOMYOSIN‐LIKE PROTEIN (NEUROSTENIN)
Authors: Mahendran C. , Nicklas W. J. , Berl S.
Published: October 2006

Abstract— The isolation of brain actomyosin‐like protein (neurostenin) with a Ca2+ ‐sensitive component is described. The addition of 1 mm EGTA results in approximately 50 per cent reduction in MgATPase activity. The inhibition can be released by a free Ca2+ concentration of 10−6m. Dialysis of the protein complex against low ionic strength medium followed by centrifugation results in a loss of Ca2+ sensitivity in the pelleted protein. Ca2+ sensitivity can be restored by reprecipitating this desensitized complex in the presence of the 70.000 g supernatant. The protection of sulphhydryl groups during desensitization and reconstitution procedures is essential. This Ca2+ regulatory property is similar, in these respects, to other actomyosin‐like proteins.