bluuebunny/crossref_metadata_2025 huggingface dataset:
STIMULATION OF SYNAPTOSOMAL PROLINE UPTAKE BY SERUM ALBUMIN
Authors: Peterson N. A. , Raghupathy E. , Estey S. J. , Tan C. H. , Salfi M.
Published: October 2006

Abstract— The accumulation of proline by synaptosomal fractions from adult brain cortices is strongly stimulated by serum albumin. Albumin at a concentration of 1 mg/ml increased the recovery of proline from the fraction by approx 2‐fold. This effect was not due to any contaminant but rather due to the albumin molecule itself. Several other proteins tested failed to stimulate synaptosomal accumulation of proline, indicating that the stimulation due to albumin is not a general protein effect. The possibility that albumin stimulates synaptosomal proline accumulation by virtue of its fatty acid binding property is discussed.
FOUR PROTEIN POLYMORPHISMS IN PIGEON BRAIN EXTRACTS DETECTED BY TWO‐DIMENSIONAL GEL ELECTROPHORESIS
Authors: Schenker T.
Published: October 2006

Abstract— Proteins of the brain extracts of 85 individual pigeons (Columba livia) were mapped by two‐dimensional gel electrophoresis. The method is a modification of O'Farrell'S technique and separates proteins first by charge and then by molecular weight. There were three proteins, A, B and D which had each a variant form. The positions of these six proteins on the gel corresponded to the following pH values and molecular weight values: protein A1, 6.4/43,000; A2, 6.6/43,000; B1, 5.7/41,000; B2, 5.8/40,000; D1, 6.2/22,000; D2, 6.2/21,000. The variants are genetically determined, since protein A, B and D each occurred in three phenotypes (A1, A1A2 and A2; B1, B1B2 and B2; D1, D1D2 and D2) corresponding to the three possible genotypes. From the observed frequencies of the phenotypes the following allele frequencies were calculated: allele A1, 72%; A2, 28%; B1, 15%; B2, 85%; D1, 74%; D2, 26%. A fourth protein named C occurred in four different forms (C1, 7.2/37,000; C2, 7.2/36,000; C3, 7.1/37,000; C4, 7.1/36,000) and six phenotypes (C1, C1C2, C2, C1C3, C2C3 and C4C3). This polymorphism is also interpreted as being genetically determined. The four alleles coding for the four protein C forms had the following frequencies: allele C1, 62%; C2, 27%; C3, 10.5%; C4, 0.5%.
CHARACTERIZATION OF HIGH AFFINITY CHOLINE UPTAKE BY TORPEDO CALIFORNICA T‐SACS
Authors: Rothlein Joan E. , Parsons Stanley M.
Published: October 2006

Abstract— The high affinity choline uptake system present in T‐sacs prepared from Torpedo californica electric organ was shown to be insensitive to external Ca2+ and to be absolutely dependent on external NaCl, with optimal uptake at approx 200 mM‐NaCl. Both Na+ and Cl− separately stimulate uptake. Uptake also exhibited an optimum at approx 10mM‐external K+. Uptake was completely inhibited at 4°C. Approximately 50% of newly accumulated [3H]choline was released by depolarization of T‐sacs regardless of the time or method of depolarization.
NEUROCHEMICAL ASPECTS OF NEURONAL ONTOGENESIS IN THE DEVELOPING RAT CEREBELLUM: CHANGES IN NEUROTRANSMITTER AND POLYAMINE SYNTHESIZING ENZYMES
Authors: Gilad Gad M. , Kopin Irwin J.
Published: October 2006

Abstract— Changes in the activities of several specific enzymes were measured in the cerebellum during development. Early transient increases were found in both ornithine decarboxylase and S‐adenosylmethionine decarboxylase, enzymes involved in the initial steps of polyamine synthesis. Different patterns of changes were found in neurotransmitter synthesizing enzymes. Tyrosine hydroxylase activity achieved adult levels very early, by 3 days after birth, and remained at this level. Glutamic acid decarboxylase activity, while very low at early stages, increased rapidly before birth and then after a lag period of 10 days started to increase rapidly, directly related to the general growth of cerebellar weight and protein content. Choline acetyltransferase activity started to increase rapidly, reaching a peak of about 100% of adult levels at 3‐7 days after birth; the activity then gradually declined and at 20 days, after reaching a low of about 55% of adult values, gradually started to increase, reaching adult levels later than 40 days after birth. The development of protein carboxymethylase activity was similar to that of glutamic acid decarboxylase, directly related to the general growth of the cerebellum. Several interpretations of the results are discussed.
RELATIONSHIP BETWEEN THE 4‐AMINOBUTYRATE BYPATH AND THE OXIDATION OF 2‐OXOGLUTARATE IN RAT BRAIN MITOCHONDRIA
Authors: Lopes‐Cardozo M. , Albers R. W.
Published: October 2006

Abstract— A method is described to evaluate simultaneously the contributions of 2‐oxoglutarate oxidation and the GABA bypath to succinate production in isolated rat brain mitochondria.

2‐Oxoglutarate oxidation is under respiratory control whereas the activity of the GABA shunt is but slightly affected by the mitochondrial energy state.

The oxidation of GABA is half‐maximal with 5mm‐GABA. GABA does not affect 2‐oxoglutarate oxidation. 1 mm‐2‐oxoglutarate is optimal for GABA oxidation, whereas higher concentrations inhibit the shunt activity.

The rate of GABA oxidation observed in vitro (5 nmol/min.mg mitochondrial protein) is comparable to the activity of the shunt under in viuo conditions.

The control and the compartmentation of GABA oxidation are discussed.
STIMULATION BY PHOSPHATE OF THE ACTIVATION OF GLUTAMATE APODECARBOXYLASE BY PYRIDOXYL‐5′‐PHOSPHATE AND ITS IMPLICATIONS FOR THE CONTROL OF GABA SYNTHESIS
Authors: Martin Sandra Bloom , Martin David L.
Published: October 2006

Abstract— Previous studies have shown that inorganic phosphate relieves the inhibition of brain glutamate decarboxylase by ATP. Since the evidence suggested that inhibition by ATP resulted in formation of the inactive apoenzyme, it was possible that Pi might relieve this inhibition by promoting activation of the apoenzyme by its cofactor, pyridoxal‐5′‐phosphate. We have investigated this possibility using apoenzyme from rat brain. In most experiments, apoenzyme was prepared by incubating glutamate decarboxylase with 20 μM‐aminooxyacetate followed by exhaustive dialysis. Activation was studied by incubating the enzyme with pyridoxal‐P under various conditions after which the amount of holoenzyme formed was measured by a 5 min enzyme assay. In the absence of Pi there was an initially rapid but incomplete activation by pyridoxal‐P which stopped after 15‐20 min. The amount of holoenzyme formed after 20 min increased without saturating as the concentration of pyridoxal‐P was raised from 0.03 to 250 μm Addition of 1‐10mm‐Pi increased the initial rate of activation and the final degree of activation. Pi stimulated activation whether present initially or added after 15 min, indicating that incomplete activation in the absence of Pi was not attributable to destruction of pyridoxal‐P or irreversible inactivation of the enzyme. Pi reduced the concentration of pyridoxal‐P, giving half maximal activation from about 10 μm to about 0.07 μm. Pi also stimulated the residual enzyme activity in the apoenzyme preparation in the absence of added pyridoxal‐P, suggesting that Pi may convert the holoenzyme to a more active form. Pi had very similar effects on glutamate apodecarboxylase from vitamin B6‐deficient rats and also stimulated the activation of apoenzyme which had been prepared by dissociation of the cofactor by treatment with glutamate, indicating that stimulation by Pi is unrelated to the method of preparing apoenzyme. Activation was also strongly stimulated by methylphosphonate and arsenate and weakly stimulated by sulfate. Trichloromethylphosphonate, cacodylate, pyrophosphate and AMP had little or no effect. The results suggest that Pi relieves the inhibition by ATP, at least in part, by promoting the activation of glutamate apodecarboxylase, and that Pi may be an important factor in the regulation of glutamate decarboxylase in vivo.
LACTOPEROXIDASE‐COUPLED IODINATION OF BOVINE CHROMAFFIN GRANULES
Authors: Blakeborough P. , Louis C. F.
Published: October 2006

Abstract— Chromaffin granules were iodinated with lactoperoxidase at either their external or internal membrane surfaces. When iodination of internal soluble granule proteins and membrane phospholipids was minimized, the majority of the membrane proteins, including the 83,000 component, were iodinated. Components with molecular weights 63,000, 61,000, 51,000, 44,000, 32,000, 26,000 and 19,000 had a higher 125I specific activity than did the other membrane components, suggesting they were more accessible at the outer membrane surface than were the other components. In the presence of detergent, the iodination of all membrane components was increased more than 10‐fold; the incorporation of 125I was now similar to their Coomassie Blue staining intensity in disc gels, indicating that all components were equally accessible to lactoperoxidase. In the presence of detergent, iodine incorporation into the MW 83,000 and 16,000 components was stimulated approx 100‐fold.

The MW 83,000, 63,000, 61,000 and 37,000 components incorporated significant amounts of 125I when granule membranes were iodinated from their internal surface, suggesting these components have a portion of their polypeptide chain accessible at the inner membrane surface. Thus the MW 83,000 component, which we identified as dopamine β hydroxylase, and the MW 63,000/61,000 components, which are part of the membrane ATPase, can be iodinated from both membrane surfaces. This would suggest that these are transmembrane proteins. However, the major portion of all the proteins in this membrane were inaccessible to lactoperoxidase at either membrane surface.
NERVE FIBER OUTGROWTH FROM DORSAL ROOT GANGLIA: ION DEPENDENCY OF NERVE GROWTH FACTOR ACTION
Authors: Stach Robert W. , Stach Bettie M. , West Norman R.
Published: October 2006

Abstract– Embryonic sensory neurons have an absolute requirement for the nerve growth factor to survive and grow fibers, at least in vitro. We have now shown that the inorganic cations, magnesium and potassium are also necessary for the survival of these cells. On the other hand, calcium is not needed for the survival of the sensory neurons, but is needed for the neurons to grow fibers. Therefore, by changing the concentration of calcium ions in the culture medium it is possible to separate the two actions (survival and fiber outgrowth) of the nerve growth factor on sensory neurons.
CHARACTERIZATION AND DEVELOPMENTAL CHANGES OF UDP‐GALACTOSE‐CERAMIDE GALACTOSYL TRANSFERASE IN A RAT CNS AXOLEMMA‐ENRICHED FRACTION. DIFFERENCES AND SIMILARITIES OF THE ENZYME ASSOCIATED WITH THE MICROSOMAL AND MYELIN FRACTIONS
Authors: Costantino‐Ceccarini Elvira , Cestelli Alessandro , DeVries George H.
Published: October 2006

Abstract— The properties of rat CNS UDP‐galactose‐ceramidc galactosyltransferase in an axolemma‐enriched fraction (AXL), microsomes, and myelin simultaneously isolated with the AXL was characterized using a newly developed assay system. The microsomal enzyme utilized either magnesium or manganese equally well as the divalent cation at 3.3 mm, while both the myelin and AXL enzyme preferred manganese over magnesium at this concentration. The microsomal enzyme was more stable to heat inactivation than the myelin or AXL enzyme. The AXL galactosyltransferase had the highest specific activity at 15 days (8‐fold higher than that of the microsomes) and dramatically decreased in specific activity with development. The developmental profile of the myelin enzyme paralleled that of the AXL although the absolute specific activity was lower than that of AXL. In contrast, the specific activity of microsomal enzyme was quite low at the earliest age then sharply increased to 25 days and gradually decreased with further development. The specific activity of the enzyme in AXL isolated from Quaking mouse was dramatically decreased (about 5% of control levels) whereas both whole homogenate and microsomal specific activity were decreased to 35% of control levels. These data indicate that AXL and myelin contain a galactosyltransferase with properties which are unique relative to those of the microsomal fraction. The possible functional significance of these findings with respect to myelination is discussed.
NONEXISTENCE OF A TYPE C MONOAMINE OXIDASE IN RAT BRAIN
Authors: Toyoshima Yoshif , Kinemuchi Hiroyasu , Kamijo Kazuya
Published: October 2006

Abstract— The possible existence of type C MAO, distinct from type A and type B, in circumventricular structures of rat brain was examined by histological studies on the inhibitory effects of clorgyline. a preferential type A MAO inhibitor and deprenyl, a preferential type B inhibitor, on enzyme. Brain slices were preincubated with the inhibitors and then incubated with 5‐HT, the substrate for type A MAO, and stained for MAO activity. Deposits of the product formazan were detected in circumventricular structures of slices of brain preincubated with clorgyline and deprenyl at concentrations of 10‐7–10‐4m at room temperature for 5 min. When the slices were preincubated with either of these inhibitors at room temperature for 60 min, strong activity was observed in this region, whereas when they were preincubated with either 10‐5m‐clorgyline or 10‐5m‐deprenyl for 20 and 30 min at 37°C, no MAO activity was seen in any region of the brain. Thus, at the higher preincubation temperature, lower concentrations of each inhibitor and a shorter preincubation period were required for inhibition of the enzyme. Preincubation for 60 min at 37°C with a combination of 10‐7m‐clorgyline and 10‐8m‐deprenyl did not inhibit the enzyme in the circumventricular region completely, but at the same temperature, concentrations of 10‐7m of both inhibitors inhibited the enzyme completely in 10min, Thus the effects of the inhibitors are synergistic. These results indicate that the inhibitory effects of the two inhibitors on the enzyme in circumventricular structures of the brain is time‐ and temperature‐dependent. Moreover, the activity seems to be sensitive to deprenyl even when 5‐HT is used as substrate. The results do not support the idea of the existence of type C MAO, distinct from type A and type B MAO.
DEPENDENCE OF BRAIN TRYPTAMINE FORMATION ON TRYPTOPHAN AVAILABILITY
Authors: Warsh Jerry J. , Coscina Donald V. , Godse Damodar D. , Chan Peter W.
Published: October 2006

Abstract— The dependence of rat brain tryptamine (TA) formation on tryptophan availability was investigated. Rat brain TA was found to accumulate linearly with respect to time over 90min following pargyline (75 mg/kg. i.p.). The in vivo rate of brain TA appearance was estimated to be 0.1 nmol/g/h. After tryptophan loading the accumulation of brain TA and 5‐HT in pargyline‐pretreated rats was linearly related to both brain and plasma tryptophan concentrations. Low doses of tryptophan (5–10 mg/kg. i.p.) produced statistically significant increments in brain TA formation. The findings of this study indicate that the in vivo formation of TA in rat brain is directly dependent upon brain and plasma tryptophan concentrations.
LOCALIZATION OF THE THY‐1 ANTIGEN IN THE CEREBELLAR CORTEX OF RAT BRAIN BY IMMUNOFLUORESCENCE DURING POSTNATAL DEVELOPMENT
Authors: Barclay A. Neil
Published: October 2006

Abstract— At birth in the rat brain the Thy‐1 antigen was present at 10% of the adult level and increased rapidly to reach near adult levels after 3 weeks. Localization studies by immunofluorescence on sections of rat cerebellar cortex during this period showed that at day 5 there was weak fluorescence associated mainly with the molecular layer and some fibre‐like structures in the centre of the folium; no fluorescence was found around the cells of external granular layer. From 5 to 16 days there was a rapid increase in Thy‐1 immunofluorescence with noticeably higher levels associated with the white matter than the molecular layer. However, by 21 days the reverse was found’ with lower levels in white matter than in the molecular layer with a similar distribution to that observed previously in adult rat cerebellum. Small rings and patches of fluorescence were observed in the molecular and granular layers. The results indicated that Thy‐1 was present on axons, mature neurons and their processes. In addition, Thy‐1 immunofluorescence was found in the pia‐arachnoid until around day 16.
APPARENT IN VIVO ACETYLCHOLINE TURNOVER RATE IN WHOLE MOUSE BRAIN: EVIDENCE FOR A TWO COMPARTMENT MODEL BY TWO INDEPENDENT KINETIC ANALYSES
Authors: Vocci Frank J. , Karbowski Michael J. , Dewey William L.
Published: October 2006

Abstract— Acetylcholine turnover has been determined in whole mouse brain using a newly available high specific activity [3H]choline (70 Ci/mmol). Animals were killed at various time points (0.25–10 min) after pulse adminstration of [3H]choline (Ch) by microwave irradiation of the head. Steady‐state levels of ACh were determined by radioenzymatic analysis as described by Goldberg & McCaman (1973) as modified by McCaman & Stetzer, 1977. Ch levels were determined by a modification of the method of McCaman & Stetzer (1977). Radiolabelled metabolites of [3H]Ch were separated by selective extraction of [3H]Ch and [3H]ACh inio tetraphenylboron in 3‐heptanone (Carrollet al., 1977) coupled with an enzymatic separation of [3H]Ch from [3H]ACh. A precursor‐product relationship was verified for Ch and ACh specific activities. Acetylcholine turnover rate was determined by the biosynthesis ratio method (Schuberthet al., 1969, Method 1) and by the finite‐differences method (Neffet al., 1971, Method 2). Both methods of kinetic analysis revealed two distinct turnover rates for acetylcholine. In the first phase (0.25–1.5 min post‐[3H]Ch), the ACh turnover rate averaged 22nmol/g/min (both methods). During the second phase, (2–10 min) acetylcholine turnover rates were significantly (P < 0.05 and P < 0.01) lower; i.e. 7nmol/g/min (Method 1) and 5.9 nmol/g/min (Method 2). The data are consistent with a 2‐compartment model for ACh turnover in whole mouse brain. Additionally, the method described for the separation of radiolabelled metabolites of [3H]Ch allows an accurate determination of ACh turnover in as little as 2 mg of tissue.
EFFECTS OF l‐ISOPROPYLNOREPINEPHRINE, 3‐ISOBUTYL‐1‐METHYL XANTHINE AND DIBUTYRYL CYCLIC AMP ON HEXOSE UPTAKE AND METABOLISM BY RAT STRIATAL SLICES1
Authors: Wilkening Doug , Makman Maynard H.
Published: October 2006

Abstract— Rat striatal slices in vitro undergo a number of changes in the pattern of their carbohydrate metabolism when incubated with either dibutyryl cyclic AMP or with the beta‐adrenergic agonist l‐isopropylnorepinephrine (IPNE) plus the phosphodiesterase inhibitor 3‐isobutyl‐1‐methylxanthine (IBMX). We have, in previous reports, shown that the content of glycogen in the slices is reduced by approx 50% upon incubation with these agonists. We now report that the rate of hexose uptake as measured by 3H uptake from a medium containing 1 mm‐glucose with a trace of [3H]2‐deoxyglucose (2‐DOG) is reduced by 20–25% compared to basal uptake rates. The rate of lactic acid production by the slices is approximately doubled and a small decrease in O2 uptake is also observed. The data are consistent with the conversion of the metabolism of a population of glycogen‐containing cells in the slises, upon incubation with dibutyryl cyclic AMP or TBMX + IPNE, from primarily oxidative metabolism using an extracellular glucose source to primarily glycolytic metabolism using the cells’ own glycogen stores. The findings reported here in vitro are in good agreement with studies reported in the literature concerning changes in the in vivo levels of brain glycogen and lactic acid in mice following the injection of drugs which act upon beta‐adrenergic receptors.
POST‐MORTEM CHANGES IN HIGH AFFINITY CHOLINE UPTAKE
Authors: Klemm Nikolai , Kuhar Michael J.
Published: October 2006

Abstract— When animals were killed by decapitation and the heads kept refrigerated at 2–4°C. high affinity choline uptake was maintained up to 3 days post‐mortem. At 5 days post‐mortem, there was a significant reduction in uptake. In tissues kept at 2–4°C for 1 day, the ionic dependence, drug sensitivity and kinetic parameters of uptake were identical to that of control tissues. At 3 days post‐mortem, intact synaptosomal profiles, although with features characteristic of degenerating neuronal tissues, were observed in electronmicroscopic studies. In tissues maintained at room temperature, however, the uptake activity was nearly completely gone by 1 day. It is concluded that high affinity choline uptake is maintained for days, a surprisingly long time, in tissues kept in the cold immediately after death.

When pentylenetetrazol or pentobarbital were administered to rats in order to activate or depress the choline uptake, it was found that the activity‐related changes in choline uptake undergo a reversal in post‐mortem tissues. The changes in uptake were significantly lost by 10min post‐mortem and totally absent by 30min post‐mortem. In vitro studies with whole hippocampi indicate that the postmortem reversal in activity‐related changes in uptake is temperature‐dependent. It is concluded that because of post‐mortem reversals in activity‐related states of uptake the true magnitude of these activity‐related changes in uptake may be underestimated by existing methods of assay. Acetylcholine levels in synaptosomal preparations did not clearly correlate with levels of choline uptake.
DEVELOPMENTAL CHANGES IN THE DISTRIBUTION OF 3‐HYDROXY‐3‐METHYLGLUTARYL COENZYME A REDUCTASE AMONG SUBCELLULAR FRACTIONS OF RAT BRAIN 1
Authors: MALTESE WILLIAM A. , VoLPE JOSEPH J.
Published: October 2006

—The distribution of 3‐hydroxy‐3‐methylglutaryl coenzyme A (HMG‐CoA) reductase (EC 1.1.1.34) relative to that of several biochemical markers has been studied in subcellular fractions prepared from the brains of rats, aged 4 days to adult, by differential centrifugation. In the brains of 10‐day‐old animals fractions which sedimented at 800 g (P1 and 9000 g (P2) contained 28% and 65% respectively of the total reductase activity. A similar distribulion of the microsomal marker, NADPH‐cytochrome c reductase, suggested that the HMG‐CoA reductase activity in the low‐speed pellets was due to substantial contamination of these fractions with endoplasmic reticulum. When P2 was fractionated on a discontinuous sucrose gradient, the distributions of protein, RNA and NADPH‐cytochrome c reductase paralleled that of HMG‐CoA reductase, indicaling a non‐specific association of endoplasmic reliculum and HMG‐CoA reductase with all of the structures sedimenting in P2. As brain maturation proceeded and a greater percentage of total brain protein (primarily associated with myelin) sedimenled in P1, the subcellular distributions of HMG‐CoA reductase and the microsomal marker changed in a parallel way. By 21 days P1 contained nearly all of the reductase activity. Because the specific activity of HMG‐CoA reductase in P1 decreased steadily between 4 and 21 days, while the specific activity of 2′:3′‐cyclic nucleotide 3′‐phosphohydrolase in this fraction increased in a coordinate fashion, we conclude that the reductase is not an integral component of myelin, and probably is associated exclusively with the endoplasmic reticulum included in P1. In view of the developmental changes in the distribution of HMG‐CoA reductase among subcellular fraclions, we suggest that whole homogenates (or comparable tissue extracts) should be utilized to evaluate reductase activity in the developing brain.
LEVELS OF NOREPINEPHRINE AND DOPAMINE IN MOUSE BRAIN REGIONS FOLLOWING MICROWAVE INACTIVATION‐RAPID POST‐MORTEM DEGRADATION OF STRIATAL DOPAMINE IN DECAPITATED ANIMALS
Authors: Blank C. LeRoy , Sasa Suleiman , Isernhagen Rick , Meyerson Laurence R. , Wassil David , Wong Peter , Modak Arvind T. , Stavinoha William B.
Published: October 2006

—The effects of 2 methods of killing on norepinephrine and dopamine in mouse brain regions were examined. One method utilized decapitation, while the other method utilized heating with microwave irradiation concentrated on the head. The norepinephrine and dopamine contents of the cerebellum, medulla‐pons, midbrain, diencephalon, hippocampus, corpus striatum, and cerebral cortex were determined by methods using liquid chromatography with electrochemical detection. Dopamine content in striatum was also quantitated by the method of gas chromatography with mass fragmentography. A significantly lower value for decapitated animals, as compared to the microwave heated group, was found only for dopamine exclusively in the striatum.

Activities of the enzymes tyrosine hydroxylase, DO PA decarboxylase, monoamine oxidase, and catechol‐o‐methyltransferase in the striatum were also examined. These enzymes were totally inactivated by the microwave heating, except catechol‐o‐methyltransferase which was decreased approx 80%. These results support either (1) the existence of a substantial pool of dopamine in the striatum with a very rapid turnover rate or (2) a decapitation‐related release and destruction of striatal dopamine. Measurements of 3‐methoxytyramine in the striatum exhibit post‐mortem increases corresponding to the decreases of dopamine. Use of the rapid tissue enzyme inactivation technique suggests that in vivo levels of this O‐methylated dopamine metabolite are an order of magnitude lower than the results normally obtained after killing by decapitation.
Effects of glycine and glyoxylate on cerebral glucose oxidation in vitro
Authors: Dennis M. J. , Clarke J. T. R.
Published: October 2006

In Patients with nonketotic hyperglycinemia (NKHG), the principal route of glycine catabolism in the CNS is interrupted by an hereditary defect in the glycine cleavage reaction [5, 10‐methylenetetrahydrofolate: ammonia hy‐droxymethyltransferase (decarboxylating, oxidizing); EC 2.1.2.10] (ANDO el al, 1968; Perryet al, 1975). The resulting accumulation of glycine in cerebral tissue of affected infants is invariably associated with the development of severe brain damage, though the mechanism of the damage is still unknown.

The rapidity of onset of the condition, which often occurs within a few hours after birth, along with the severity and irreversibility of the cerebral damage, suggests that some critical metabolic process is affected by the accumulation of glycine or one of its normally minor metabolites. The study reported here was undertaken to determine the effects of glycine and its α‐ketoacid metabolite, glyoxylate, on glucose oxidation in immature rat brain slices, and whether glyoxylate accumulation in NKHG might account for the severe brain damage occurring with the disease. The results showed that although glyoxylate markedly inhibited cerebral glucose oxidation in vitro, excess amounts of the compound could not be demonstrated in NKHG brain.
Subcellular Distribution of Glutamate Decarboxylase in Rat Olfactory Bulb: High Content in Dendrodendritic Synaptosomes
Authors: Quinn Michael R. , Cagan Robert H.
Published: October 2006

: The olfactory bulbs in the CNS contain reciprocal dendrodendritic synapses between the granule cells and the secondary dendrites of mitral cells. Based on pharmacologic and electrophysiologic evidence, these synapses are believed to utilize GABA as an inhibitory neurotransmitter. A dendrodendritic synaptosomal fraction has been isolated from rat olfactory bulbs. The upper portion (PB) of the crude nuclear pellet contains 30–40% of the GAD (glutamate decarboxylase) activity of the olfactory bulb homogenate. When PB is purified on a discontinuous sucrose density gradient, 78–85% of the GAD activity is localized to the region containing the dendrodendritic synaptosomes, which were identified by transmission electron microscopy. The presence of a substantial proportion of GAD, the enzyme that catalyzes synthesis of GABA, in the DDS provides neurochemical support for the hypothesis that GABA functions at the reciprocal dendrodendritic synapses in the olfactory bulb.
α‐Guanidinoglutaric Acid in Cobalt‐Induced Epileptogenic Cerebral Cortex of Cats
Authors: Mori Akitane , Akagi Masayuki , Katayama Yasuto , Watanabe Yoko
Published: October 2006

: Guanidino compounds in the cobalt‐induced epileptogenic cerebral cortex of cats were fluorometrically analysed by a JASCO G‐520 guanidino compounds analyser, and an unknown high peak was observed in the chromatogram that was identical to the peak of authentic α‐guanidinoglutaric acid. In another experiment, the substance was extracted from the cobalt focus tissue, converted into dimethylpyrimidyl derivative‐butylester, and analysed by a GC/MS technique. The mass spectrum of the substance was identical to the dimethylpyrimidyl derivative of α‐guanidinoglutaric acid butylester (M+= 365).
Choline High‐Affinity Uptake and Metabolism and Choline Acetyltransferase Activity in the Striatum of Rats Chronically Treated with Neuroleptics
Authors: Pedata F. , Sorbi S. , Pepeu G.
Published: October 2006

: High‐affinity uptake of choline and choline acetyltransferase activity (ChAT) were measured in the striatum of rats treated for 45–60 days with haloperidol (1 mg/kg per os) and pimozide (1 mg/kg per os) daily and with fluspirilene (1 mg/kg i.m.) twice a week. Haloperidol and fluspirilene caused a 29%, and pimozide a 38%, increase in high‐affinity uptake of choline. They also caused a significant decrease in ChAT activity: haloperidol, 20%; pimozide, 27%; and fluspirilene, 42%. In rats treated with fluspirilene for 65–80 days the metabolism of [3H]choline taken up by striatal synaptosomes was investigated. A 33% increase in total radioactivity, a significant increase in labelled acetylcholine (ACh), a relative decrease in labelled choline, and no change in labelled phosphorylcholine and betaine were found. It is concluded that the increase in high‐affinity choline uptake caused by chronic administration of neuroleptic drugs is associated with a parallel increase in choline utilization for ACh formation. On the other hand, the decrease in ChAT activity does not appear to influence ACh formation.
l‐Pipecolate Formation in the Mammalian Brain. Regional Distribution of Δ1Pyrroline‐2‐carboxylate Reductase Activity
Authors: Garweg G. , Rehren D. Von , Hintze U.
Published: October 2006

: lPipecolate formation exhibits considerable regional differences in the central nervous system of the mouse, dog, and monkey, as reflected in measurements of the activity of Δ1‐pyrroline‐2‐carboxylate reductase (E.C. 1.5.1.1). The rate of reduction of Δ1‐piperidine‐2‐carboxylate was high in certain telencephalic and diencephalic regions, lower in the brain stem, and not measurable in the cerebellum and spinal cord. In addition to Δ1‐piperidine‐2‐carboxylate, Δ1‐pyrroline‐2‐carboxylate was also found to be a substrate for the same enzyme in homogenates of mouse forebrain. Enzyme kinetic data for both substrates and, in addition, for NADH were derived from determinations using enzyme fractions of mouse telencephalon. The discussion is based on earlier findings concerning the utilisation of d‐proline in the neuronal protein synthesis of mouse brain.
Turnaround of Axoplasmic Transport of Selected Particle‐Specific Enzymes at an Injury in Control and Diisopropylphosphorofluoridate‐Treated Rats
Authors: Schmidt Robert E. , C. Yu Margaret J. , McDougal, David B.
Published: October 2006

: Reversal of direction (turnaround) of axonal transport of particle specific enzyme activities was studied at a ligature placed on rat sciatic nerve. In the principal experiment, the ligature remained on the nerve in vivo several hours, allowing enzyme activities (acetylcholinesterase, acid phosphatase, and monoamine oxidase) to accumulate immediately proximal to the tie. The nerve was then tied a second time, proximal to the first tie, and incubated in vitro for several more hours. Accumulation of enzyme activities just distal to the second tie was measured. This second accumulation, of activities traveling in the retrograde direction, was shown to be the result of turnaround in several ways. (1) The increase in activity distal to the second tie was equal to the decrease in activity proximal to the first. (2) The increase in enzyme activities distal to the second tie was greatly reduced when the accumulation proximal to the first tie was trapped by placing a third tie between the first and second ties. (3) It was shown that the activity that accumulated distal to the second tie could not have been in retrograde motion at the time of the first tie. (4) Accumulation distal to the second tie was not a function of the length of nerve segment included between the two ties. In contrast to the consistent occurrence of turnaround of orthograde flow, turnaround of retrograde flow could not be demonstrated. Turnaround transport was blocked by incubation in the cold and in the presence of NaCN or vinblastine. The turnaround process operated on all three enzymes studied, suggesting that it operates on lysosomes and mitochondria, as well as on the endoplasmic reticulum‐like material bearing acetylcholinesterase. Evidence for the participation of the transport process in the renewal of AChE in the distal portions of the axon was obtained in experiments using diisopropylphosphorofluoridate and cycloheximide.
Effects of N‐Ethylmaleimide Treatment on the Action Potential Na+‐Ionophore of Cultured Neuroblastoma Cells
Authors: Panini Aruna , Blumenthal Kenneth
Published: October 2006

: Treatment of murine neuroblastoma N18 cells with N‐ethylmaleimide under conditions that favor diminution of membrane potential leads to a 65% increase in the rate of veratridine‐stimulated, tetrodotoxin‐sensitive Na+ uptake and to a 50% decrease in the concentration of veratridine required for half‐maximal stimulation. This modification does not appear to occur in N18 cells having a normal membrane potential of approx. ‐40 mV. The data are consistent with the involvement of a sulfhydryl group in the Na+ channel inactivation gate and in the conformational change in this gate which results in closing of the channel.
Lack of Effect of Repeated Electroconvulsive Shock on [3H]Spiroperidol and [3H]5‐Hydroxytryptamine Binding and Cholinergic Parameters in Rat Brain
Authors: Atterwill C. K.
Published: October 2006

: Repeated electroconvulsive shock (ECS) administered on alternate days for 10 days produced no changes in rat striatal [3H]spiroperidol binding measured 24 h after the last shock compared to anaesthetised controls. Similarly, there was no change in whole brain specific [3H]5‐HT binding. Sodiumdependent high affinity [3H]choline uptake (HAUC) and ChAT were also unaltered in striatal and hippocampal samples following repeated ECS. Acute administration of Pentylenetetrazol did produce an increase in hippocampal HAUC immediately postictally. However, ECS (XI) did not change HAUC measured 1 h postictally. An effect of halothane on HAUC was noted in these experiments indicating the importance of an evaluation of anaesthetic effects in ECS studies.
No Evidence for Lateral Asymmetry of Neurotransmitters in Post‐Mortem Human Brain
Authors: Rossor M. , Garrett N. , Iversen L.
Published: October 2006

: A study of post‐mortem human brain was undertaken to establish whether there is any evidence for lateral asymmetry of neurotransmitters. Choline acetyltransferase, glutamic acid decarboxylase, α‐aminobutyric acid, dopamine and noradrenaline were measured in nine comparable areas from the left and right hemispheres of normal post‐mortem human brain. Only nigral GABA showed a left‐right difference at a significance level of 5%. These negative post‐mortem findings suggest that chemical laterality is unlikely to be an important source of error in human post‐mortem studies.
Calcium‐dependent Desensitization of Adenylate Cyclase in Rat Cerebral Cortical Slices
Authors: Partington C. R. , Edwards M. W. , Daly J. W.
Published: October 2006

Abstract— Incubation of slices of rat cerebral cortical grey matter in Krebs‐Ringer bicarbonate‐glucose buffer induced a rapid decline in the responsiveness of the adenylate cyclase in subsequently prepared membrane preparations to stimulation by various activators of the enzyme. The loss of responsiveness was time‐ and temperature‐dependent, showed an absolute dependence on extracellular calcium ions and was mimicked by the presence of serine proteases in the incubation medium. The resultant adenylate cyclase preparation was partially responsive to activation by fluoride and guanylylimidodiphosphate but had become virtually unresponsive to activation by ganglioside, trypsin, or β‐adrenergic agonists. The loss of responsiveness of adenylate cyclase was not altered if slices were incubated with depolarizing agents, putative neurotransmitters, receptor blockers, serine protease inhibitors, or adenosine deaminase. The nature of the calcium‐dependent mechanism involved in the loss responsiveness of membranal adenylate cyclase is unknown. A suggested mechanism for the loss of sensitivity is the action of a membrane‐bound, calcium‐dependent protease.
Gangliosides of Human Cerebral Astrocytomas
Authors: Traylor T. Dennis , Hogan Edward L.
Published: October 2006

Abstract: Ganglioside content and composition were examined in a series of 25 human gliomas, which were graded histologically by the criteria of Kerno‐han. The concentration of total gangliosides (lpid‐bound sialic acid [LBSA]) was decreased with respect to normal brain tissue in nearly all tumors and the extent of reduction correlated with the stage of tumor anaplasia. The distribution of individual gangliosides was altered in glial tumor tissue with an increase in proportion of the structurally simple gangliosides and reduction of polysialogangliosides. The most consistent and significant difference was the elevation of proportion of ganglioside GD3 from 4–5% of total LBSA in normal brain to 20% in the astrocytoma grade IV. The proportions of gangliosides GM2 and GD2 were also found to be elevated in all grades of the tumors. The simplification of ganglioside composition seems to be associated with transformation of the astrocyte with the accumulation of the simpler gangliosides, since the changes resemble those reported with in vitro transformation rather than those of analyses of preparations of purified glial cells.
Methionine Recycling in Brain: A Role for Folates and Vitamin B‐12
Authors: Spector Reynold , Coakley Gail , Blakely Raymond
Published: October 2006

Abstract: The recycling of methionine via homocysteine was measured in vivo in brain. After constant intravenous infusions (5 h) of both [3H‐methyl] methionine and [35S]methionine into rats, the ratios of [3H‐methyl]methionine to [35S]methionine in liver, brain and plasma were determined, Similar experiments were performed in rabbits, except that the [3H‐methyl]‐ and [3S]methionine were injected intraventricularly. If the methyl group of methionine was removed with the formation of homocysteine and then replaced by another (unlabeled) methyl group, the specific activity of the [3H‐methyl]methionine would decrease more than that of [35S]methionine; i.e., the ratio of [3H‐methyl]‐ to [35S]methionine in the tissue would decline. The results showed that the ratios of [3H‐methyl]‐ to [35S]methionine in liver and brain were less than the same ratio in plasma in the rats. The comparable ratios in the brain and CSF of rabbits were less than the ratio in the injectate. Since brain contains only one enzyme capable of remethylating homocysteine to methionine, the vitamin B‐12–dependent methyltetrahydrofolate‐homocysteine methyltransferase (EC 2.1.1.13), our results for methionine recycling via homocysteine in brain strongly support the activity of this enzyme in brain in vivo.
Protein and Glycoprotein Composition of Myelin Subfractions from the Developing Rat Optic Nerve and Tract
Authors: Lane J. D. , Fagg G. E.
Published: October 2006

Abstract: The rat optic nerve and tract (representing a relatively homogeneous part of the CNS) were utilised for a detailed examination of the protein and glycoprotein composition of developing myelin membranes. Animals aged from 5 days through to adulthood were used. Myelin fractions could first be isolated from the nerve 8 days after birth and the yield increased until 60 days of age, before declining slightly to the adult level; a similar (but possibly slightly delayed) pattern was apparent for the optic tract. The homogeneity of optic nerve myelin (compared with that from brain and spinal cord) was demonstrated by zonal centrifugation on continuous sucrose‐density gradients; myelin from both 20‐day and adult animals exhibited narrow, Gaussian‐like distributions, with 19–22% of the total myelin at the population modes. During development, the myelin density profile was shifted to a denser region of the sucrose gradients. Micro‐polyacrylamide gel electrophoretic analyses of “light” and “heavy” myelin subfractions from both optic nerve and tract indicated that the gross developmental changes in protein composition were similar to those previously described for myelin prepared from larger CNS areas, particularly the forebrain. The glycoprotein components of the myelin fractions were stained directly on micro‐gels using fluorescein isothiocyanate‐labelled concanavalin A. The relative proportion of the major high‐molecular‐weight glycoprotein decreased rapidly during the early phases of myelination. A number of lower‐molecular‐weight glycoproteins were also apparent; the proportions of these varied during development and in light and heavy myelin subfractions, but definitive data are not available to determine whether they are components of the myelin sheath or of contaminating membranes.
The Effect of Colchicine and Cytochalasin B on the Release of Taurine from the Chick Retina
Authors: Pasantes‐Morales H. , Salceda R. , Lopez‐Colomé A. M.
Published: October 2006

Abstract: The effect of colchicine (0.5 mM) and of cytochalasin B (10−4 M) on the release of [35S]taurine from the isolated chick retina, upon stimulation by 68.5 mM‐KCl, 10−5 M‐veratridine and 10 mM‐glutamate, was studied. Cytochalasin and colchicine effects on taurine release were compared with those on K+‐stimulated release of [3H]dopamine and [3H]GABA. Colchicine caused a marked decrease of the [35S]taurine release evoked by the three stimulatory agents; it also decreased [3H]dopamine release without affecting that of [3H]GABA. Cytochalasin B significantly decreased the efflux of [35S]taurine stimulated by glutamate or veratridine without altering that evoked by 68.5 mM‐KCl. Cytochalasin practically suppressed the [3H]dopamine‐stimulated release and slightly decreased that of [3H]GABA. This drug produced a high increase in the spontaneous release of labeled GABA and taurine. These results suggest that the release of taurine and GABA from the chick retina probably occurs through different mechanisms. It is suggested that taurine release may be related to a process involving contractile proteins.
Cyclic AMP‐Generating Systems in Cell‐Free Preparations from Guinea Pig Cerebral Cortex: Loss of Adenosine and Amine Responsiveness Due to Low Levels of Endogenous Adenosine
Authors: McNeal E. T. , Creveling C. R. , Daly J. W.
Published: October 2006

The accumulations of radioactive cyclic AMP elicited by adenosine, norepinephrine, and histamine in adenine‐labeled vesicular entities of a particulate fraction from guinea pig cerebral cortex are greatly reduced as a result of prolonged preincubation. The presence of adenosine deaminase during preincubations largely prevents the loss of adenosine, norepinephrine and histamine responses. Adenosine deaminase was inactivated by deoxycoformycin prior to stimulation of cyclic AMP accumulation by adenosine or amines. If adenosine deaminase is not inactivated, responses to norepinephrine are not significant and histamine responses are reduced by 50%. Adenosine deaminase cannot restore responsiveness of the cyclic AMP‐generating systems. It is proposed that, in participate fractions of guinea pig cerebral cortex, low levels of adenosine cause a slow loss of receptors and/or of coupling of receptors to cyclic AMP‐generating systems.
Bovine Peripheral Nervous System Myelin P2 Protein: Chemical and Immunological Characterization of the Cyanogen Bromide Peptides
Authors: Weise M. J. , Hsieh D. , Hoffman P. M. , Powers J. M. , Brostoff S. W.
Published: October 2006

Cleavage of bovine P2 protein by cyanogen bromide (CNBr) produced peptide fractions CN1, CN2, and CN3 which were isolated by gel filtration chromatography. CN2 was found to contain two NH2‐terminals (lysine and valine) and accounted for both of the cysteine residues of P2. When reduced carboxymethylated P2 (RCM‐P2) was digested with CNBr, peptides CN1 and CN3 were obtained as were (1) a peptide with NH2‐terminal lysine (Lys) that contained no homoserine and only one cysteine residue and (2) a peptide with NH‐2‐terminal valine (Val) that was co‐eluted with CN3. These data and the chemical characterization of all the CNBr peptides obtained from P2 and RCM‐P2 suggest that isolated P2 protein has a structure composed of the CNBr peptides in the order CN3‐CN1‐CN2(Val)‐CN2(Lys) with an intrachain disulfide bond between the cysteine residues located in the two constituent peptides of CN2, CN2(Lys) and CN2(Val), To locate the neuritogenic region(s) within the P2 protein structure, CN1, CN2, and CN3 were tested for the ability to induce experimental allergic neuritis (EAN) in Lewis rats. The disease‐inducing sites of P2 protein were found only in CN1; neither CN2 nor CN3 produced disease. EAN induced by CN1 was comparable to that induced with P2 protein as determined by disease onset, clinical symptoms, and histologic lesions.
Axonal Transport of [3H]Fucose‐Labeled Glycoproteins in Two Intra‐Brain Tracts of the Rat
Authors: Padilla Stephanie S. , Morell Pierre
Published: October 2006

[3H]Fucose was stereotaxically injected into the dorsalateral geniculate body (DLGB) of adult male rats, and 1 h to 10 days post‐injection the DLGB and projection site (striate cortex) were dissected out and solubilized in 1% sodium dodecyl sulfate. Each sample was analyzed for acid‐precipitable radioactivity, and radioactivity in different molecular weight classes was determined following discontinuous gel electrophoresis in cylindrical gels. The specificity of transport of radioactive glycoprotein to the striate cortex was determined by autoradiography of brain sections. Acid‐precipitable radioactivity in the DLGB peaked at 5 to 6 h, plateaued, and then declined over the time course studied. The electrophoretic distribution pattern was complex, five bands containing fucosylated protein being initially prominent, as a percentage of radioactivity on the gel, and then decreasing with time. Two discrete waves of glycoproteins arriving at the visual cortex (between 3 and 4 h and between 12 and 48 h) were observed. Quantitative differences in distribution of molecular weight classes were noted between glycoproteins transported in these two waves. Of particular interest were rapidly turning‐over proteins of molecular weights of 110,000 and 120,000 (half‐time of less than 1 day). A study of the hippocampal commissural pathway, following introduction of radioactivity into one hippocampal formation, was also conducted. The electrophoretic distribution patterns of proteins, and the changes in distribution with time, were similar to the situation in the DLGB. However, in the contralateral hippocampus three discrete waves of transport were resolved (2 to 3 h, 4 to 5 h, and then a continued gradual increase followed by another prominent rise between 1 and 2 days). Relative turnover times of different protein peaks in the hippocampal and DLGB‐cortical system were also different.
Activity of Pyridoxamine as a Substrate for Brain Pyridoxal Kinase
Authors: Gregory Jesse F.
Published: October 2006

The substrate activity of pyridoxamine (PM) for brain pyridoxal (PL) kinase was examined in view of a recent report which indicated that PM was a poor substrate for this enzyme. Bovine brain PL kinase was shown by liquid chromatography to catalyze the phosphorylation of PM (Km= 65 μm). The identity of the reaction product, pyridoxamine 5′‐phosphate, was confirmed by its ability to act as a substrate for liver pyridoxine (pyridoxamine) 5′‐phosphate oxidase. These results, which indicate that PM is a good substrate for brain PL kinase, are consistent with the proposed role of intracellular phosphorylation in the uptake of vitamin B‐6 brain tissue.