bluuebunny/crossref_metadata_2025_split huggingface dataset:
NONRIBOSOMAL INCORPORATION OF AMINO ACIDS INTO THE TROPONIN‐LIKE PROTEIN FROM SYNAPTOSOMES
Authors: CARLIN R. K. 
Published: October 2006

Abstract—A preparation of synaptosomal cytoplasm was isolated from forebrain of young rats and incubated with various amino acids in vitro. Incorporation of amino acids into protein was observed. This incorporation did not occur by ribosomal protein synthesis. The amino acid incorporating system was not stimulated by ATP and was inhibited by calcium. The system incorporated amino acids enzymatically.An electrophoretic analysis of the synaptosomal preparation, following incubation in the presence of radioactive amino acids, showed only three labelled protein species (molecular weights 37,000, 26,000 and 20,000). This incorporation of amino acids was found to have a high degree of specificity for three protein species. Migration of the three protein species was found to be nearly identical to that of rabbit muscle troponin. The proteins incorporating amino acids were also found to have other characteristics of the troponin subunits. A possible role of troponin modification is discussed.
THE LOCALIZATION OF MITOCHONDRIAL NADP‐DEPENDENT ISOCITRATE DEHYDROGENASE IN NORMAL AND HYPOXIC CONDITIONS
Authors: GROMEK A. , PASTUSZKO A. 
Published: October 2006

Abstract—NADP‐dependent isocitrate dehydrogenase is localized in both external and internal membranes and in the mitochondrial matrix from brains of adult and newborn animals. Electrophoretic studies indicate that the mitochondrial enzyme occurs in the form of two isoenzymes; the isoenzyme of the external membranes behaves similarly to that of the cytoplasm. Ischaemia in adult animals results in a decrease in enzyme specific activity, particularly in external membranes, while in the mitochondrial fraction of the newborn the activity of the enzyme increased.
SUBCELLULAR LOCALIZATION OF α‐MELANOCYTE‐STIMULATING HORMONE IN THE RAT HYPOTHALAMUS1
Authors: BARNEA AYALLA , OLIVER CHARLES , PORTER JOHN C. 
Published: October 2006

Abstract—Homogenates of male rat hypothalami were fractionated by means of differential centrifugation, and α‐melanocyte‐stimulating hormone (α‐MSH) in the various fractions was quantified by radioimmunoassay. Of the total quantity of α‐MSH in the homogenate, 36% was recovered in the 11,500 g pellet and 31% sedimented between 11,500 and 105,000 g. α‐MSH was not detected in the 105,000 g supernatant fluid. When the 900 g supernatant fluid was fractionated on continuous sucrose density gradients at non‐equilibrium conditions, two populations of particles containing α‐MSH were observed. When fractionated at equilibrium conditions, the two populations were recovered in a single band. These sedimentation characteristics indicate that the particles that contain α‐MSH differ in size but are similar in density. After hypo‐osmotic shock, the large particles containing α‐MSH were not demonstrable, whereas the small particles appeared to be resistant to such treatment. In their sedimentation, the particles containing α‐MSH were indistinguishable from particles containing thyrotropin releasing hormone (TRH) but were separable from those that contained luteinizing hormone releasing hormone (LHRH). It is suggested that the large particles containing α‐MSH are synaptosomes.
MUSCARINIC REGULATION OF cAMP IN MOUSE NEUROBLASTOMA
Authors: BLUME A. J. , CHEN C. , FOSTER C. J. 
Published: October 2006

Abstract—The neurotransmitter acetylcholine regulates cAMP concentrations in mouse neuroblastoma cells (clone NS20). In these cells, the action of acetylcholine appears to be specific: it does not alter basal concentrations of cAMP, but prevents the elevation of cAMP which is mediated by either adenosine or prostaglandin E1. The receptor for acetylcholine which is involved in this phenomenon has been identified as muscarinic. Pilocarpine and carbamylcholine, but not acetate or choline, will substitute for acetylcholine. Furthermore, the action of 10 μM‐carbbamylcholine is blocked by ≥ nM concentrations of atropine, isopropamide or 3‐quinuclidinylbenzilate, but not by mM concentrations of d‐tubocurarine or hexamethonium.Of eight cholinergic antagonists tested, decamethonium and succinylcholine were the only two which were able to substitute for acetylcholine. These two antagonists are known to cause depolarization of post‐synaptic cells. Decamethonium and succinylcholine appear to interact with the same muscarinic receptor, as their actions are also blockèd by low concentrations of 3‐quinuclidinylbenzilate. In addition to these two depolarizing antagonists, the ionophores, valinomycin, A23187 and X537A, were also found to prevent elevation of cAMP concentrations. The involvement of specific membrane depolarization as being the active agent by which acetylcholine inhibits elevation of cAMP concentrations is discussed.
STUDIES ON FORMATION OF γ‐GLUTAMYLAMINES IN RAT BRAIN AND THEIR SYNTHETIC AND CATABOLIC ENZYMES
Authors: TSUJI M. , MATSUOKA Y. , NAKAJIMA T. 
Published: October 2006

Abstract—γ‐Glutamylation of p‐tyramine, noradrenaline, dopamine and serotonin in rat brains was demonstrated by intraventricular injections of the radioactive amines and isolation of the γ‐glutamylamines from the acidic extract of the rat brains. Formation of these γ‐glutamylamines was proved to be catalysed by γ‐glutamyltranspeptidase prepared from both rat kidney and brain. However, these compounds were degraded by γ‐glutamylcyclotransferase of rat brain, but not by the emzyme of rat kidney.
OCCURRENCE OF ALKANES IN BRAIN MYELIN. COMPARISON BETWEEN NORMAL AND QUAKING MOUSE
Authors: BOURRE J. M. , CASSAGNE C. , LARROUQUERE‐REGNIER S. , DARRIET D. 
Published: October 2006

Abstract—Alkanes, a new class of neurolipid, were found in mouse brain, the level being reduced in the Quaking mutant. These hydrocarbons are concentrated in myelin; minor amounts being found in microsomes, mitochondria and synaptosomes. The average recovery is 7.1 μg/mg in normal myelin, 2.2 in the Quaking myelin. The distribution pattern of these alkanes was determined by gas liquid chromatography and was found to differ in normal and Quaking myelin; the hydrocarbons consist mainly of n‐alkanes ranging from C21 to C32 with even and odd aliphatic chains.
EFFECT OF DIETARY HISTIDINE ON OLFACTION, AND RAT BRAIN AND MUSCLE CONCENTRATION OF HISTIDINE‐CONTAINING DIPEPTIDES1
Authors: QUINN MICHAEL R. , FISHER HANS 
Published: October 2006

Abstract—Young adult male rats were fed three diets; one was devoid of histidine (HF), the second supplied the maintenance requirement (M, 3.7% protein, 0.07% histidine), and the third provided an optimal amount of histidine for growth (G, 10.0% protein, 0.21% histidine). The M diet was pair‐fed with the HF diet. After an 11 weeks experimental period, some HF animals were given the M diet for an 11 day repletion period. On the HF diet carnosine in the olfactory bulb and pectoral muscle, homocarnosine in whole brain and hemoglobin were sharply and significantly reduced in concentration below the levels found in the M and G groups. During the 11 day repletion period all concentrations except for hemoglobin returned to normal. Comparison of olfactory ability between M and HF rats showed no significant difference indicating that if carnosine is involved in olfaction, the amount required must be very small. Restricted food intake had no apparent effect on the concentration of histidine‐containing dipeptides but did influence hemoglobin concentration. The HF rats appeared to exhibit an altered state of emotionality compared to either of the other two treatment groups.
SEPARATION OF ACETYLCHOLINE AND CATECHOLAMINE CONTAINING SYNAPTIC VESICLES FROM BRAIN CORTEX
Authors: Nagy Agnes , Várady Gy. , Joó F. , Rakonczay Z. , Pilc A. 
Published: October 2006

Abstract— Synaptic vesicles were prepared from guinea‐pig cerebral cortex on a continuous D2O‐H2O(1:1)‐sucrose gradient and purified in the presence of 1 mm‐EGTA by chromatography on columns of glass beads of controlled pore size. As markers, endogenous ACh, NA, dopamine and DβH were measured.Two distinct populations of synaptic vesicles were recognized between the layers of 0.2–0.3 m‐ and 0.3–0.5 m‐sucrose, which differed from each other both in electron microscopic appearance and transmitter content. The less dense vesicles had a much higher ACh content than the more dense vesicles which were composed mainly of somewhat larger particles with high NA and dopamine content. DβH was found to be present in substantial amounts in guinea‐pig cortex and was located in the synaptic vesicle fractions having high CA content.After glass bead chromatography the vesicle preparations were morphologically homogeneous, practically free from other subcellular elements and were contaminated with each other by not more than 10%The yields were 0.2 and 0.1 mg protein g cortex−1 tissue for ‘cholinergic’ and ‘adrenergic’ vesicle preparations, respectively.
PURIFICATION OF BOVINE PINEAL HYDROXYINDOLE O‐methylTRANSFERASE BY IMMUNOADSORPTION CHROMATOGRAPHY
Authors: Kuwano R. , Yoshida Y. , Takahashi Y. 
Published: October 2006

AbstractA procedure is described for the use of immunoadsorption chromatography of hydroxyindole O‐methyltransferase (HIOMT). HIOMT was purified from bovine pineal extract by affinity chromatography on immunoglobulins (Ig)‐Sepharose. The overall purification was about 45‐fold; the yield was 84%. This enzyme constitutes about 2.0% of the soluble proteins in the pineal gland. The enzyme represented a single precipitin line on Ouchterlony double diffusion plate and immunoelectrophoresis. Ultracentrifugation analysis indicated the existence of molecular aggregates of enzyme and disc gel electrophoresis showed one main protein band and several minor bands. However sodium dodecyl sulphate (SDS) gel electrophoresis showed a single protein band with subunit molecular weight 38,000 demonstrating bovine pineal HIOMT to be polymer enzyme of a single subunit. The properties of the purified enzyme including disc gel electrophoretic pattern, the effect of pH, chemicals and substrates and immunological properties were identical with those of the crude enzyme.
MOUSE BRAIN TYROSINE HYDROXYLASE AND GLUTAMIC ACID DECARBOXYLASE FOLLOWING TREATMENT WITH ADRENOCORTICOTROPHIC HORMONE, VASOPRESSIN OR CORTICOSTERONE
Authors: Dunn Adrian J. , Gildersleeve Nancy B. , Gray Harry E. 
Published: October 2006

AbstractThe activities of tyrosine hydroxylase (TH) and glutamic acid decarboxylase (GAD) from several mouse brain regions were assayed following repeated administration of adrenocorticotrophic hormone (ACTH), lysine vasopressin (LVP) or corticosterone. Although similar treatments with ACTH have been shown to result in changes of catecholamine turnover and GABA content, no changes in the activity of either TH or GAD were observed in any brain region. Likewise LVP had no effect on either enzyme. Since the assays for TH were performed with concentrations of tyrosine and tetrahydrobiopterin cofactor below their respective Michaelis constants, this suggests that the changes of catecholamine turnover are not mediated by changes of TH activity. Twice daily corticosterone adrninistration for four days increased TH activity in the hypothalamus but not in any other brain region.
FURTHER EVALUATION OF POLYPEPTIDE SYNTHESIS IN CEREBRAL ANOXIA, HYPOXIA AND ISCHEMIA
Authors: Morimoto. Kazuyoshi , Brengman Joan , Yanagihara Takehiko 
Published: October 2006

AbstractThe alteration of polypeptide synthesis was evaluated with microsomes isolated from anoxic rabbit, hypoxic rat and ischemic gerbil brains to estimate the extent of functional or structural changes in polyribosomes in situ and the extent of artifact during tissue preparation. By using two‐stage experimentation with combination of control and pathological microsomes and supernatant, it was found that the previously observed effects on microsomal or polyribosomal polypeptide synthesis in the above pathophysiological conditions were mainly the reflection of the alteration of polyribosomes in situ rather than the artifact during tissue preparation by degradative processes. In support of this finding. the use of inhibitors of degradative enzymes did not significantly protect microsomes either in normal or in pathological conditions. It was noted that the decline of tissue pH, to a certain extent, could be correlated with dysfunction of polyribosomes both in situ and during tissue preparation in cerebral hypoxia and anoxia. Since there is little change in ATP level, it was postulated that the alteration of pH in situ is responsible for the observed suppression of polypeptide synthesis in vitro at least in cerebral hypoxia. This hypothesis was supported by the subsequent experiments with incubation of brain slices and homogenization of brain tissue under various pH. It was emphasized that the environmental biochemical elements surrounding polyribosomes in cytoplasm should be evaluated as possible contributing factors for polyribosomal dysfunction in such pathological conditions as cerebral anoxia, hypoxia or ischemia if the alteration of energy state does not explain the phenomenon entirely.
THE EFFECT OF MORPHINE TOLERANCE and DEPENDENCE ON CELL FREE PROTEIN SYNTHESIS1
Authors: Rederick F , Craves B. , Loh Horace H. , Meyerhoff James L. 
Published: October 2006

AbstractA cell free system consisting of polyribosomes and pH 5 factors of the cytosol was isolated from mouse brain. This system actively promoted the incorporation of radiolabeled amino acids into protein in vitro. Addition of exogenous morphine to a cell free protein synthetic system isolated from chronically morphinized, placebo treated, or naive mouse brain had no effect on the relative synthetic capacity of the system. In addition, morphine did not alter the response to a synthetic mRNA, polyuridylic acid. However, both the polyribosomes and pH 5 factors isolated from chronically morphinized mouse brain were more effective in promoting amino acid incorporation into protein relative to the corresponding fractions from placebo treated mice. Acrylamide gel electrophoresis of the proteins in the incubation mixture showed the increased amino acid incorporation was the result of a general quantitative increase in the specific activity of all of the proteins synthesized by the cell free system.
STUDIES ON THE REGULATION OF GABA SYNTHESIS: SUBSTRATE‐PROMOTED DISSOCIATION OF PYRIDOXAL‐5′‐PHOSPHATE FROM GAD
Authors: Miller L. P. , Martin D. L. , Mazumder A. , Walters J. R. 
Published: October 2006

Abstract—The association between glutamate decarboxylase (GAD) and its cofactor, pyridoxal‐5′‐phos‐phate (pyridoxal‐P), was studied using 20,0000 supernatant of rat brain. In this preparation GAD required added pyridoxal‐P to maintain a linear reaction rate beyond 5 min of incubation. Following exhaustive dialysis the enzyme was more than 83% saturated with cofactor indicating that the cofactor was tightly bound to the enzyme. When incubations were performed in the presence of glutamate and without added pyridoxal‐P there was a progressive inactivation of the enzyme which was dependent on the glutamate concentration. This lost activity was almost completely recovered by addition of pyridoxal‐P to the dialyzed glutamate‐inactivated enzyme. The results suggest that glutamate inactivates GAD by promoting the dissociation of pyridoxal‐P from the enzyme thereby producing inactive apoen‐zyme which can be reactivated by combining with available pyridoxal‐P. This interpretation is supported by the finding that progress curves for the reaction were accurately described over a 30 min incubation period and 10‐fold glutamate concentration range by an integrated rate equation which takes the glutamate‐promoted dissociation of cofactor into account. The progressive inactivation could not be attributed to denaturation of the enzyme, impurities in the substrate, effects of pH, depletion of substrate, protein concentration, sulfhydryl reagents or product inhibition. The results presented here also show that certain precautions must be adopted to accurately measure GAD activity in the absence of added pyridoxal‐P as has been widely done in studies of drug action. Specifically, measurements must be made at short times of incubation and low concentrations of glutamate to minimize the glutamate‐promoted inactivation of the enzyme.
IMMUNOCHEMICAL AND BIOCHEMICAL STUDIES DEMONSTRATING THE IDENTITY OF A BOVINE SPINAL CORD PROTEIN (SCP) AND A BASIC PROTEIN OF BOVINE PERIPHERAL MYELIN (BF)
Authors: Deibler Gladys E. , Driscoll Bernard F. , Kies Marian W. 
Published: October 2006

Abstract—A protein extracted from bovine peripheral myelin (BF) and a protein extracted from bovine spinal cord (SCP) have been shown to be identical: the proteins cross‐react immunochemicaliy with each other but not with highly purified CNS myelin basic protein. Neither BF nor SCP have anti‐encephalitogenic activity. Their electrophoretic behavior is the same at three different pH values. Their apparent molecular weight by sodium dodecyl sulfate‐gel electrophoresis is 13,800 ± 550. The amino acid compositions of the proteins are essentially identical. BF and SCP each contain 2 cysteine residues and have valine at the C terminus. The 23 major tryptic peptides are identical on peptide maps. Circular dichroic analyses yield essentially identical curves, which, when computed by best‐fit curve analysis, indicate that each has 0%α helix and a large percentage of β structure.
PROPERTIES AND REGIONAL DISTRIBUTION OF TRYPTOPHAN HYDROXYLASE IN THE CHICKEN BRAIN
Authors: Mclennan I. S. , Lees G. J. 
Published: October 2006

Abstract—Tryptophan hydroxylase in young chicken brain had a pH optimum of 7.5–8, depending on the buffer used. It had apparent Km values for tryptophan and tetrahydrobiopterin of 49 μM and 32 μM respectively. The enzyme in chicken brain, but not rat brain, was cold‐shock labile but was stable for up to 4 days at — 20°C. Lability was observed both in tissues and homogenates of these tissues subjected to cold shock, but the extent of loss of activity varied between brain regions. Supernatant fractions did not lose activity after cold shock. The highest level of tryptophan hydroxylase was found in the rostral region of the chicken brainstem. High levels were also found in the caudal region of the brainstem, the midbrain, thalamus, caudate and cerebral cortex. The cerebellum and optic chiasma contained only traces of activity.
CYCLIC NUCLEOTIDE LEVELS IN NORMAL AND BIOLOGICALLY FRACTIONATED MOUSE RETINA: EFFECTS OF LIGHT AND DARK ADAPTATION
Authors: DeVries G. W. , Cohen A. I. , Hall I. A. , Ferrendelli J. A. 
Published: October 2006

Abstract— The content of cyclic AMP and cyclic GMP was measured in whole eyes and in normal retinas from C57BL(6)J mice, in receptorless retinas from congenic mice homozygous for the receptor dystrophy gene (rd/rd), and in retinas from mice treated postnatally with monosodium glutamate. Normal retinas contain approx 320 μg of protein: dystrophic (rd/rd) retinas contain approx 110μg of protein, lack rods but possess some surviving cone somata and terminals: glutamate‐modified retinas contain approx 200 μg of protein and have both a reduced area and thickness with a marked deficiency of ganglion cells and amacrine cells. In normal mice, more than 90% of the cyclic GMP, but only 607, of the cyclic AMP of the whole eye was in the retina. In normal dark‐adapted retinas isolated under dim red light cyclic AMP and cyclic GMP content was 4.1 and 20.2pmol/retina, respectively. The content of both cyclic AMP and cyclic GMP was 40% less, 2.5 and 11.5pmol/retina, respectively, in light‐adapted retinas. In dark‐adapted retinas isolated under infra‐red light, cyclic AMP content was 40%, higher than that in retinas isolated under dim red light; cyclic GMP content was the same under these two conditions. Receptorless retinas contained approx 50% as much cyclic AMP and only 1‐2% as much cyclic GMP as normal retinas. Although glutamate‐modified retinas also had approx 50% as much cyclic AMP, they contained 60‐85%, as much cyclic GMP as normal retinas. Light decreased by 30‐50% levels of both cyclic AMP and cyclic GMP in glutamate‐modified retinas, but only reduced cyclic nucleotide levels in receptorless retinas by 20%.These data indicate that 95% or more of the cyclic GMP is in photoreceptor cells, whereas cyclic AMP is more evenly distributed throughout the retina. In addition, both cyclic AMP and cyclic GMP levels are influenced by light‐ and dark‐adaptation.
INDUCED ACETYLCHOLINE RELEASE FROM ACTIVE PURELY CHOLINERGIC TORPEDO SYNAPTOSOMES1
Authors: Michaelson D. M. , Sokolovsky M. 
Published: October 2006

Abstract—Viablse, purely cholinergic synaptosomes were prepared from the electric organ of Torpedo ocellata and partially purified by differential and sucrose density centrifugation. The synaptosomes contain acetylcholine (ACh), synaptic vesicles, cytoplasmic markers and mitochondria. No adherent postsynaptic membranes were detected. K+ depolarization as well as the ionophore A23187 mediate Ca2+ permeation into the synaptosomes and the consequent release of ACh. Mg2+ does not evoke ACh release whereas Sr2+ and Ba2+ can replace Ca2+ in evoking K+ depolarization induced ACh secretion. In accordance with the calcium hypothesis of stimulus–secretion coupling, both K+ depolarization and the ionophore A23187 seem to mediate the release of the same population of ACh molecules. The mode of action of the ionophore X537A differs from that of A23187. X537A acts independently of Ca2+ and induces the release of a larger fraction of the ACh contained in the fractionated nerve terminals. These results demonstrate that the Torpedo synaptosomes contain the neurosecretion apparatus in a functional active state. This preparation extends the utility of synaptosomes for structural and functional biochemical studies of neurotransmission, as it uniquely contains only one neurosecretion system (cholinergic).
ANTI‐WHOLE WHITE MATTER SERUM INHIBITS INCORPORATION OF GLUCOSE AND GALACTOSE INTO THE LIPIDS OF MYELINATING SPINAL CORD CULTURES
Authors: Lehrer G. M. , Maker H. S. , Silides D. J. , Weiss C. , Bornstein M. B. 
Published: October 2006

Abstract—Myelin formation was inhibited in fetal mouse spinal cord cultures in the presence of serum from rabbits with experimental allergic encephalomyelitis produced by inoculation of whole bovine spinal cord white matter in complete Freund's adjuvant. Controls were exposed to decomplemented serum. Replacement of serum in inhibited cultures on the 18th day in vitro (DIV) with control serum (disinhibited) resulted in the appearance of visible myelin within 2–3 days. From 20 to 23 DIV, d‐[U‐14C]glucose or d‐[U‐14C]galactose was present in all media. Total protein, DNA, gangliosides and galactolipids were reduced by 21% in inhibited cultures, and activity of 2′,3′‐cyclic nucleotide 3′‐phosphohydrolase was reduced by 50%. There was little reduction in the incorporation of glucose carbon (21–23 DIV) into several lipid classes examined. Labelling of cerebrosides by galactose carbon in inhibited cultures was only 12% of that of controls while there was no reduction in the labelling of neutral lipid–cholesterol and the glycerophosphatides. Galactolipid labelling by [14C]galactose in the disinhibited cultures was intermediate between inhibited and control cultures. Differences in the effects of inhibiting medium on the incorporation of glucose and galactose carbon indicate that ceramide synthesis is less affected than is galactose incorporation to form cerebroside.