bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence for the Presence of CDP‐Ethanolamine: 1,2‐diacyl‐sn‐glycerol Ethanolaminephosphotransferase in Rat Central Nervous System Myelin
Authors: Wu Po‐Shun , Ledeen Robert W. 
Published: October 2006

Abstract: Highly purified rat brain myelin isolated by two different procedures showed appreciable activity for CDP‐ethanolamine: 1,2‐diacyl‐sn‐glycerol ethanolaminephosphotransferase (EC 2.7.8.1). Specific activity was close to that of total homogenate and approximately 12–16% that of brain microsomes. Three other lipid‐synthesizing enzymes, cerebroside sulfotransferase, lactosylceramide sialyltransferase, and serine phospholipid exchange enzyme, were found to have less than 0.5% the specific activity in myelin compared with microsomes. Washing the myelin with buffered salt or taurocholate did not remove the phosphotransferase, but activity was lost from both myelin and microsomes by treatment with Triton X‐100. It resembled the microsomal enzyme in having a pH optimum of 8.5 and a requirement for Mn2+ and detergent, but differed in showing no enhancement with EGTA. The diolein Km was similar for the two membranes (2.5–4 × 10−4m), but the CDP‐ethanolamine Km was lower for myelin (3–4 × 10−5m) than for microsomes (11–13 × 10−5m). Evidence is reviewed that this enzyme is able to utilize substrate from the axon in situ.
An Apparent Paradox in the Occurrence, and the In Vivo Turnover, of C‐Terminal Tyrosine in Membrane‐Bound Tubulin of Brain
Authors: Nath Jayasree , Flavin Martin 
Published: October 2006

Abstract: Tubulin tyrosine ligase catalyzes the reversible addition of tyrosine to the C‐terminus of tubulin α chains. By using ligase and carboxypeptidase A in conjunction, we have previously shown that brain cytoplasmic tubulin exists in three forms: 15–40% already has C‐terminal tyrosine, another 10‐30% can accept additional tyrosine, and about one‐half is an uncharacterized species which is not a ligase substrate. A membrane‐bound fraction of brain tubulin, purified by vinblastine precipitation from a detergent extract, has been found to differ by the complete absence of preexisting tyrosine. The membrane fraction from which tubulin was extracted also contained masked forms of both ligase and a distinct detyrosylating enzyme, which can be released by detergent extraction. The turnover of α‐chain C‐terminal tyrosine in vivo was studied by incubating brain mince with labeled tyrosine, or injecting it intracerebrally, under conditions where protein synthesis was inhibited. Tyrosine appeared to turn over to about the same extent in membrane‐bound, as in soluble, tubulin. This apparently paradoxical result was not due to ATPase in the membrane fraction, which might have allowed ligase‐catalyzed exchange between free and fixed tyrosine. Authentic [14C]tyrosylated tubulin added to the brain membrane fraction was not detyrosylated or subject to endoprotease digestion during subsequent procedures to isolate tubulin. The unexpected finding that tubulin tyrosylated at the C‐terminal in vivo appears to be in the “non‐substrate” fraction points toward a possible resolution of the paradox.
Inhibition of [3H]Spiroperidol Binding by In Vitro Addition of Ethanol
Authors: Hruska Robert E. , Silbergeld Ellen K. 
Published: October 2006

Abstract: The in vitro addition of ethanol at concentrations greater than 0.2% produced an inhibition of [3H]spiroperidol binding. This inhibition was competitive, lowering the affinity without altering the maximum number of sites. Both the rates of association and dissociation were altered such that the ligand spent less time attached to the receptor. Since the binding was competitive, little inhibition was seen at ligand concentrations greater than 300 pm. These results are important for in vitro studies when drugs are dissolved in ethanol, and also for in vivo studies on the effects of ethanol.
Nucleocytoplasmic Transport of RNA and Protein Synthesis in Developing Brain from Normal and Undernourished Rats
Authors: Duvilanski Beatriz H. , de Guglielmone Alicia E. Ramirez , Gomez Carlos J. 
Published: October 2006

We have reported earlier that neonatal undernutrition in the rat produces a transient decrease in brain nuclear RNA synthesis, but a marked and permanent increase in the labeling ratio of nuclear to microsomal RNA following a 1‐h in vivo pulse of labeled precursor (Ramirez de Guglielmone et al., 1974). Although these findings would suggest that posttranscriptional processing and transport of RNA transcripts are permanently affected by this condition, it is also possible that the observed alterations could be due to changes in cytoplasmic RNA metabolism.We report here the effect of neonatal undernutrition on nucleocytoplasmic transport of messenger and ribosomal RNA in a cell‐free system that precludes detectable nuclear lysis. We also attempt to relate alterations in transport to polysomal aggregation and protein synthesis in viva.
Hydrolysis of Galactose from Glycolipids and Glycoprotein by Young Rat Brain β‐Galactosidases Immobilized to Sepharose 4B
Authors: Yeung Kwok‐Kam , McKinney Richard A. , Dain Joel A. 
Published: October 2006

AbstractAn extract of glycosidic enzymes from young rat brain was immobilized to cyanogen bromide‐activated Sepharose 4B. Most glycosidases retained approximately 10‐25% of their activities after immobilization. Immobilized β‐galactosidases were used repeatedly without detectable loss of enzyme activity in the hydrolysis of p‐nitrophenyl‐β‐d‐galactopyranoside. In addition to the synthetic substrate, the immobilized rat brain β‐galactosidases could also hydrolyze galactose from lactose, galactosylcerebroside, asialofetuin, and GM1‐ganglioside. The hydrolysis of GM1‐ to GM2‐ganglioside was confirmed on TLC.
Axonal Transport of [35S]Methionine‐Labeled Proteins in Two Intra‐Brain Tracts of the Rat
Authors: Padilla Stephanie S. , Morell Pierre 
Published: October 2006

Abstract[35S]Methionine 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. Samples were analyzed for acid‐precipitable radioactivity, and radioactivity in different molecular weight classes was determined following discontinuous gel electrophoresis on both tube and slab gels. Acid‐precipitable radioactivity in the DLGB peaked by 4 h and then declined over the time period studied. The molecular weight distribution pattern was complex and did not change appreciably with time. Radioactivity in the striate cortex arrived in at least three waves: rapidly transported proteins arrived between 2 and 4 h; a second wave of transport began to arrive at about 7 h post‐injection and there was a slight rise in specific activity for 2 days; finally, at 3 days post‐injection, there was a steep increase with the arrival of the bulk of the transported material. The electrophoretic distribution pattern of proteins arriving in the first wave included 40–50 identifiable bands ranging in molecular weight from 13,000 to 200,000. Of particular interest was a radioactive band of apparent molecular weight of 110,000, which was prominent at 4 h, but by 12 h showed very little labeling. The second wave of radioactivity contained primarily proteins of molecular weight classes already present, although there were quantitative differences. Several proteins in the molecular weight range of 43,000 to 78,000 were identifiable as characteristic of the third wave of transported material. Results from a study following injection of a hippocampus were similar: the electrophoretic distribution pattern of radioactive proteins extracted from the injected hippocampus resembled that of the DLGB, and also did not vary appreciably with time, while radioactive proteins in the contralateral hippocampus had an electrophoretic distribution pattern similar to that of the striate cortex and changed with time in a similar manner.
Density Profile and Basic Protein Measurements in the Myelin Range of Particulate Material from Normal Developing Mouse Brain and from Neurological Mutants (Jimpy; Quaking; Trembler; Shiverer and its mid Allele) Obtained by Zonal Centrifugation
Authors: Bourre J. M. , Jacque C. , Delassalle A. , Nguyen‐Legros J. , Dumont O. , Lachapelle F. , Raoul M. , Alvarez C. , Baumann N. 
Published: October 2006

AbstractThe particulate material of aquaeous homogenate of forebrain was separated by zonal centrifugation in a continuous 0.4‐1.2 m‐sucrose gradient after sedimentation at 100,000 g to eliminate the soluble material. Based on the absorbance at 280 nm, four major peaks were obtained from adult normal mice corresponding to 1.1 m (A), 0.68 m (B), 0.35 m (C), and 0.12 m (D) sucrose. The two smaller and lighter peaks, C and D, were not present when purified myelin was separated by the same procedure. B consisted of pure compact myelin; A was made of vesicles, sometimes with a double membrane. Throughout development, the myelin peak shifted from 0.58 m in young animals to 0.70 m in very old ones. Moreover, the myelin peak B drastically increased during development, as compared with peak A.‐In the Trembler, the profile was close to normal, with a slightly higher yield of myelin which also peaked at a higher density. In the quaking, there were only two shoulders in the myelin density range at 0.68 m and 0.75 m; in the Jimpy only a faint shoulder was seen, at approximatively 0.67 m. In the shiverer, B was absent and only an A peak was present, at approximatively 0.85‐0.90 m, which contained non‐compact lamellar membranes and myelin figures with an abnormal major dense line. In the mid (an allele of shiverer) the density profile resembled the one obtained in the shiverer (one peak in the 0.88 m region). When considering myelin basic protein (MBP) content in the normal developing animal, it was minimum in fraction A, mainly found in the B myelin peak, but also present in the light fraction (C + D). In young animals this latter peak was prominent, in contrast to the adult. In the Trembler mutant, the profile was close to normal; in the quaking, MBP was mainly found in peak A (0.85 m), and in the Jimpy MBP was very low and nearly constant throughout the gradient (with faint quantities in light C + D fraction). In mid, the content was very low, with a peak in the 0.88 m region, in contrast with its shiverer allele, where MBP is hardly detected. More meaningful myelin studies can be carried out by using zonal centrifugation in continuous sucrose gradient, to determine the density of mutant myelin and the degree of myelin maturation in animals.
Presynaptic Membrane Protein Phosphorylation Modulates the Release of GABA from Preloaded Synaptosomes
Authors: Brennan M. J. W. , Cantrill R. C. 
Published: October 2006

AbstractIncubation of rat cortical synaptosomes in the presence of 1 mM ATP markedly reduced Ca2+‐dependent K+ ‐induced release of preloaded 3H‐GABA. This effect is probably dependent on phosphorylation of presynaptic membrane proteins. By contrast, the uptake of 3H‐GABA by the nerve endings was not significantly affected by phosphorylation. These data suggest that membrane protein phosphorylation and dephosphorylation may form a mechanism for the presynaptic control of transmitter release.
Chronic Alcohol Intake and Some Monogalactosyl Glycolipids of the Rat Brain
Authors: Vrbaški Snežana R. , Petrovió Gordana T. , Ristié Milosav S. 
Published: October 2006

AbstractThe effect on monogalactosyl glycolipid complement (cerebrosides with hydroxy and non‐hydroxy fatty acids, sulphatides and monogalactosyldiglyceride) after 38 weeks of feeding 25% sucrose‐32% ethyl alcohol have been studied. Chronic alcohol intake produced a statistically significant increase of cerebrosides with hydroxy and non‐hydroxy fatty acids and monogalactosyldi‐glyceride as well as decrease of sulphatides in male Wistar rats brain.
Regional Distribution of Neurotransmitter Synthesizing Enzymes in the Basal Ganglia of Human Brain
Authors: Gaspar P. , Javoy‐Agid F. , Ploska A. , Agid Y. 
Published: October 2006

Abstract:Tyrosine hydroxylase (TH, EC 1.14.16.2), glutamate decarboxylase (GAD, EC 4.1.1.15), and choline acetyltransferase (ChAT, EC 2.3.1.6), activities were used as markers of the presence of catecholaminergic, GABAergic, and cholinergic neurons in human brain. The disparity in the absolute values obtained in control caudate nucleus led us to study the pattern of distribution of these enzymes in given brain regions, with the idea that the pattern might be altered specifically in pathological conditions. The tridimensional distribution of TH, GAD, and ChAT activities was investigated within the caudate nucleus, the putarnen, and the pallidurn. In control patients, opposite rostro‐caudal and rnedio‐lateral gradients appeared for GAD and CAT; ChAT activity was higher at the caudal level and GAD activity was higher at the rostral level of caudate nucleus and putamen. In the medio‐lateral extent of putarnen and pallidurn, ChAT activity was highest in the lateral part of the putarnen; GAD was highest in the medial segment of the pallidum. Only GAD presented a particular dorsoventral pattern, the enzyme activity being highest in the ventral part of the caudate nucleus and the putarnen. No reproducible distribution was observed for TH. In Parkinsonian patients, a decrease of TH and GAD activities with abolition of gradients was observed, whereas the ChAT activity and pattern were not modified.
Phosphorylation of Synaptic Membranes
Authors: Berman Robert F. , Hullihan John P. , Kinnier William J. , Wilson John Eric 
Published: October 2006

Abstract: In vivo and in vitro phosphorylation of synaptic membrane proteins were compared. In vivo phosphorylation was carried out by injecting rats intraventricularly with 1 mCi of 32Pi‐orthophosphate. After a 40‐min isotope incorporation period, rats were decapitated and synaptic membranes isolated. In vitro phosphorylation was accomplished by incubating unlabeled synaptic membranes, isolated from noninjected rats, with 5 μM‐[γ‐32P]ATP. In vivo and in vitro32P‐labeled synaptic membranes were then fractionated electrophoretically on an SDS‐polyacrylamide (7.5%) slab gel. The Coomassie blue protein patterns for in vivo and in vitro32P‐labeled synaptic membranes were identical. In contrast, autoradiographs of these gels showed striking differences in the pattern of phosphate incorporation. Cyclic‐AMP (10 μM) maximally stimulated) the in vitro phosphate labeling of two protein bands (80,000 and 55,000 apparent molecular weight) which were not substantially labeled by the in vivo procedure.
Monoamine and Tissue Fluid Levels in Contused Spinal Cord of Sheep
Authors: Hinwood Barry G. , Yeo John D. , Kidman Antony D. 
Published: October 2006

Abstract:Methods are described for the determination of sheep spinal cord tissue fluid content and norepinephrine, serotonin, and dopamine concentrations after experimental injury. The amount of tissue fluid varied in different regions of sheep spinal cord following injury. Norepinephrine and serotonin wet weight concentrations were corrected for this variation in tissue fluid. Corrected norepinephrine wet weight cord concentrations did not change up to 3 hr after injury. Levels of serotonin at 60 min after injury were similar to controls. Dopamine was not detected in sheep spinal cord. α‐Methyl tyrosine significantly reduced fluid in the spinal cord at 75 min after injury. Hinwood B. G. et al. Monoamine and tissue fluid levels in contused spinal cord of sheep. J. Neurochem.35, 786–791 (1980).
Enzymatic Glucosylation of Dolichyl Monophosphate Formed Via Cytidine Triphosphate in Calf Brain Membranes
Authors: Scher Malka G. , Burton Willis Anne , Waechter C. J. 
Published: October 2006

Abstract:When calf brain membrane preparations containing endogenous dolichyl [32P]monophosphate (Dol‐32P), prelabeled enzymatically by [γ‐32P]‐CTP, are incubated with unlabeled UDP‐glucose, the formation of a mild acid‐labile [32P]phosphoglucolipid is observed. The biosynthesis of the [32P]phosphoglucolipid is dependent on the concentration of UDP‐glucose added, and no [32P]phosphoglycolipid appeared when UDP‐glucose was replaced by ADP‐glucose, UDP‐xylose, UDP‐galactose, UDP‐mannose, or UDP‐glucuronic acid. The 32P‐labeled product formed by the UDP‐glucose‐dependent reaction is chemically and chromatographically identical to glucosylphosphoryldolichol. Several enzymatic parameters of the glucosylation of the specific pool of Dol‐P, synthesized by the CTP‐mediated kinase, and the total available pool of Dol‐P have been compared by a double‐label assay utilizing endogenous, prelabeled Dol‐32P and UDP‐[3H]glucose as substrates.
Cell‐free Synthesis of the Myelin Basic Proteins in a Wheat Germ System Programmed with Brain Messenger RNA
Authors: Matthees Joanne , Campagnoni Anthony T. 
Published: October 2006

Abstract:Poly A(+) messenger RNA (mRNA) was isolated from the brains of 3‐week‐old mice and translated in a cell‐free system derived from wheat germ. Maximal stimulation of the system by brain mRNA was observed at a relatively low K+ concentration (45 mm) and low mRNA concentration (1–10 μg/ml). The translational system was dependent on an energy‐generating system and stimulated by the addition of spermidine and transfer RNA. Under optimal conditions, incorporation was linear for almost 45 min, but the overall stimulation with brain mRNA was relatively low (about twofold). In spite of the low stimulation, analysis of the translation products indicated that in the presence of brain mRNA polypeptides which co‐chromatographed and co‐electrophoresed with the two mouse myelin basic proteins could be detected. In control experiments with liver poly A(+) mRNA, which stimulated the translational system to a greater extent than brain mRNA, no such polypeptides could be detected. In this system the ratio of synthesis of small myelin basic protein to large myelin basic protein was found to be about 4.0, which correlates well with that found in vivo.Matthees J. and Campagnoni A. T. Cell‐free synthesis of the myelin basic proteins in a wheat germ system programmed with brain messenger RNA. J. Neurochem.35, 867–872 (1980).
Thymidine Transport in the Central Nervous System
Authors: Spector Reynold 
Published: October 2006

Abstract:The mechanisms by which thymidine enters and leaves brain, choroid plexus, and CSF were investigated by injecting [3H]thymidine intravenously and intraventricularly. [3H]thymidine, with and without unlabeled thymidine, was infused at a constant rate into conscious adult rabbits. At 150 min, [3H]thymidine readily entered CSF, choroid plexus, and brain. In brain, approximately 45% of the nonvolatile radioactivity was [3H]thymidine phosphates. The addition of 0.21 mmol/kg unlabeled thymidine to the infusion syringe decreased the phosphorylation of [3H]thymidine in brain by approximately 85%; the addition of 2.1 mmol/kg of unlabeled thymidine to the infusion syringe decreased the relative entry of [3H]thymidine into CSF and brain by 40 and 78%, respectively. Two h after intraventricular injection of [3H]thymidine, [3H]thymidine was rapidly cleared from CSF, in part, to brain, where approximately 40% of the [3H]thymidine was converted to [3H]thymidine phosphates. The intraventricular injection of unlabeled thymidine (21 μmol) with the [3H]thymidine abolished the phosphorylation of [3H]thymidine in brain and significantly decreased the clearance of [3H]thymidine from the CSF. Rabbit brain slices accumulated [3H]thymidine by an energy‐dependent, saturable high‐affinity system that depended, in part, on intracellular phosphorylation of the [3H]thymidine. These results were interpreted as showing that the entry of thymidine from blood into CSF and presumably the extracellular space of brain and then into brain cells involves one or more saturable transport and/or metabolic steps.
3H]Spiroperidol Binding in Rat Striatum: Two High‐Affinity Sites of Differing Selectivities
Authors: Andorn Anne C. , Maguire Michael E. 
Published: October 2006

Abstract:[3H]Spiroperidol binding to homogenates of rat striatum is saturable and shows either monophasic or biphasic saturation isotherms under specified conditions. In poorly washed membrane fragment preparations, saturation isotherms of [3H]spiroperidol binding are monophasic, revealing an apparently homogeneous set of sites with Kp 0.6 ± 0.3 nm and density 440 ± 80 fmol/mg protein. However, equilibrium displacement studies of [3H]spiroperidol binding at this site indicate an a‐adrenergic component in addition to the previously described dopaminergic component. In thoroughly washed membrane fragment preparations, saturation isotherms are clearly biphasic, showing an additional high‐affinity site with an approximate KD of 24 ±10 pm and an approximate density of 110 ± 20 fmol/mg protein at a protein concentration of 2.0 mg/ml. Selectivity at this site appears classically dopaminergic, suggesting that the lower affinity site is the primary source of the α‐adrenergic component of spiroperidol binding.
Attachment of the Synapse‐Specific Phosphoprotein Protein I to the Synaptic Membrane: A Possible Role of the Collagenase‐Sensitive Region of Protein I
Authors: Ueda Tetsufumi 
Published: October 2006

Abstract:The purified synapse‐specific phosphoprotein Protein I was previously shown to be degraded by a bacterial collagenase, through a series of intermediates, to a collagenase‐resistant fragment of molecular weight about 48,000 containing a phosphorylated serine residue. In this study, a purified synaptic membrane fraction containing Protein I was treated with Cl. his‐tolyticum collagenase; membrane‐bound and membrane‐free proteins were then phosphorylated using [γ‐32P]ATP and analyzed by SDS‐polyacrylamide gel electrophoresis and autoradiography. It was observed that Protein I bound to the synaptic membrane was susceptible to the collagenase and degraded to fragments of molecular weights about 68,000, 62,000, and 48,000; the 68,000 fragment remained bound to the membrane whereas the 62,000 and 48,000 fragments were dissociated from the membrane. These observations suggest that the peptide moiety of mol. wt. 6000, present in the 68,000 fragment but absent from the 62,000 fragment, may play a crucial role in anchoring Protein I to the synaptic membrane.
Tryptophan Overload in the Pregnant Rat: Effect on Brain Amino Acid Levels and In Vitro Protein Synthesis
Authors: Fando Juan L. , Domínguez Fernando , Herrera Emilio 
Published: October 2006

Abstract:The concentration of most amino acids was higher in the brains of 19‐ and 21‐day rat fetuses than in their respective mothers. After an intraperitoneal load of tryptophan to the mother, the intracerebral concentration of several amino acids (including leucine) decreased not only in the mothers, but also in their fetuses. The in vitro incorporation of pHJleucine into proteins in brain postmitochondrial supernatant fractions was enhanced in both the mothers and fetuses after tryptophan administration, but this effect disappeared when protein synthesis was calculated by using specific activities corrected for the amount of unlabeled leucine in the preparation. By this criterion, protein synthesis activity appeared similar in the brains of 19‐ and 21‐day pregnant rats but was higher in their fetuses, especially in the 21‐day subjects. Thus, protein synthesis in the brain was not altered by marked changes in the amino acid pool and more profound and prolonged metabolic disturbances must occur to cause permanent damage in the developing brain.