bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes in RNA Synthesis and Messenger RNA Content in the Cerebellum of Rats with Graft Versus Host Disease
Authors: Griffin W. Sue T. , Head Judith R. , Pardue Sibile , Morrisont Marcelle R. 
Published: October 2006

Abstract:Cerebellar RNA accumulation, synthesis, and functional capacity was studied in 14‐day‐old F, hybrid rats subjected to neonatally induced graft versus host disease (GVHD). There was a decrease in RNA synthetic rate as measured by the uptake of labeled precursors into RNA. The decrease in total cerebellar RNA synthesis was reflected both in a reduced amount of Nissl substance, visible in cresyl violet‐stained 10‐μ‐thick sections of cerebella, and in the total amount of cytoplasmic RNA isolated from individual cerebella from diseased animals compared with control littermates. Analysis of the RNA translational capacity in wheat germ protein synthesizing systems showed that RNA from experimental animals was also biologically less active. Qualitative differences between protein populations in control and diseased animals were analyzed by two‐dimensional gel electrophoresis. There were few alterations in the steady state levels of cerebellar protein. However, two‐dimensional gel electrophoresis of the peptides synthesized in vitro by RNA from control and diseased animals showed that there were several changes in the relative abundance of some mRNAs between the two RNA populations. These data show that the cerebellar RNA from rats with GVHD differs both qualitatively and quantitatively from that of controls.
Rate of Movement and Composition of Rapidly Transported Proteins in Regenerating Olfactory Nerve
Authors: Cancalon P. , Elam J. S. 
Published: October 2006

Abstract:In a previous study, three successive groups of regenerative fibers, growing initially at 5.8, 2.1, and 0.8 mm/day, were observed in the regenerating garfish olfactory nerve. In the present study, fast axonal transport in the most rapidly regenerating axons (phase I and II) has been examined. Rapid transport in phase I fibers occurs at a velocity of 208 × 9 mm/day at 23°C, a rate identical to that measured in intact nerves. This first phase of regenerating fibers represents only 3 to 5% of the original axonal population, but each fiber appears to contain 6 to 16 times more transported radioactivity than an axon in an intact nerve. Subcellular distribution of rapidly moving material in phase I and II fibers was closely related to the distribution obtained in intact nerves. Small but significant differences indicate a shift of the transported radioactivity from a heavier to a lighter axonal membranous fraction. This shift might be characteristic of the immature membrane of a growing axon. The polypeptide distribution of transported radioactivity was also very similar to that of a normal nerve, with most of the radioactivity associated with high‐molecular‐weight polypeptides.
Membrane Potentials in Cell‐free Preparations from Guinea Pig Cerebral Cortex: Effect of Depolarizing Agents and Cyclic Nucleotides
Authors: Creveling C. R. , McNeal E. T. , McCulloh D. H. , Daly J. W. 
Published: October 2006

Abstract:The distribution of [3H]triphenylmethylphosphonium ion between the medium and vesicular entities was examined in a cell‐free, particulate preparation from guinea pig cerebral cortex. This distribution followed the Nernst relationship with regard to the external potassium ion concentration and, in physiological media, indicated the maintenance of a mean trans‐membrane potential ranging from –58 to –78 mV. The neurotoxins batrachotoxin, veratridine, and grayanotoxin I, partially depolarized the preparation. Tetrodotoxin blocked the depolarization by batrachotoxin, veratridine, and grayanotoxin I. The depolarization by these neurotoxins was potentiated by the presence of anemone toxin II and presumably reflected the response of vesicular components of neuronal origin. An additional potassium‐sensitive depolarization probably represented the response of vesicular components of glial origin with an apparent transmembrane potential of –8 to –35 mV. No correlation could be demonstrated between changes in transmembrane potential and stimulation of cyclic AMP generation by a variety of agents in this preparation.
N‐Ethyl Analogues of Choline as Precursors to Cholinergic False Transmitters
Authors: Boksa P. , Collier B. 
Published: October 2006

Abstract:Cat superior cervical ganglia perfused with the choline analogue, diethylcholine, acetylated the analogue and acetyldiethylcholine was sub‐sequently released from the ganglia in response to preganglionic nerve stimulation by a Ca2‐‐dependent mechanism. Rat cerebral cortical slices incubated with monoethylcholine or diethylcholine acetylated the choline analogues, and both acetylmonoethylcholine and acetyldiethylcholine were released from the slices in response to stimulation by a high K+. concentration. In brain slices pre‐incubated with monoethylcholine, diethylcholine, or triethylcholine, acetylated derivatives of the choline analogues were found in both free and bound nerve‐ending stores, similar to the subcellular localization of [3H]acetyl‐choline (ACh) in brain slices pre‐incubated with [3H]choline; the relative distribution of each of the acetylated choline analogues between the two nerve‐ending stores differed only slightly from that of [3H]ACh. Nerve‐ending free and bound stores of acetyldiethylcholine were equally depleted when brain slices were stimulated under conditions that cause depletion of releasable acetyldiethylcholine stores; similar results were obtained with acetyltriethyl‐choline. It is concluded that the three acetylated ethyl analogues of choline fulfill the necessary criteria for identification as cholinergic false transmitters, and that, under the conditions of the present experiments with brain, the false transmitters are able to distribute similarly to ACh between nerve‐ending stores.
Studies on a Molecular Basis for the Heparin‐Induced Regulation of Enzymatic Activity of Mouse Striatal Tyrosine Hydroxylase In Vitro. Inhibition of Heparin Activation and of the Enzyme by Poly‐L‐lysyltyrosine and Poly‐L‐lysylphenylalanine and Their Constituent Peptides
Authors: Stone Audrey L. 
Published: October 2006

Abstract:Tyrosine hydroxylase was purified up to 10‐fold from hypotonic extracts of mouse striatum by heparin affinity chromatography. The purified enzyme (a) had a low Km for tyrosine (around 15 μm) and was not inhibited by tyrosine at concentrations up to 0.2 mm when tetrahydrobiopterin was cofactor and (b) was activated by heparin. The interaction of heparin with tyrosine hydroxylase was studied in ways relating to the known interaction with anti‐thrombin. Heparan and keratan sulfates failed to activate tyrosine hydroxylase in place of heparin; several fractions of the bulk heparin (constituting 5 and 15%) had enriched tyrosine hydroxylase‐activating potency; and two lysine copolypeptides (polylysyltyrosine and polylysylphenylalanine) inhibited the activation of tyrosine hydroxylase by heparin. The lysine copolymers also directly inhibited the enzyme. Heparin (but not heparan and keratan sulfates) protected tyrosine hydroxylase from this inhibition. The constituent lysyltyrosyl (but not lysylphenylalanyl) peptide inhibited tyrosine hydroxylase, and heparin also reversed this inhibition, which was sigmoidal (IC50 of 490 μM) and partially competitive with tyrosine. Tyrosine hydroxylase was purified up to sevenfold by lysyltyrosyl‐affinity chromatography. This enzyme preparation exhibited an eightfold greater sensitivity to lysyltyrosylamide than tyrosine hydroxylase purified by heparin affinity. The data indicate that tyrosine hydroxylase is regulated in vitro by a negatively charged site. Occupancy of this site by cationic effectors results in allosteric inhibition which mediates changes in the apparent Km for tyrosine.
Effect of Capsaicin Pretreatment on Substance P Binding to Synaptic Vesicles
Authors: Mayer N. , Gamse R. , Lembeck F. 
Published: October 2006

Abstract:Newborn or adult rats were pretreated with 50 mg kg–1 capsaicin. At the age of 2 to 4 months, binding of 1251‐labelled Tyr8‐substance P to synaptic vesicles prepared from different regions of the nervous system was examined. In both groups, capsaicin pretreatment led to a significant decrease in the number of binding sites in dorsal roots and spinal cord without having an effect on affinity. This decrease parallels the depletion of the substance P content (Gamse et al., 1980) and can be explained by degeneration of primary sensory neurons in newborn treated rats and by depletion of vesicles in adult treated rats.
Development and Regional Distribution of Methionine Synthetase in Rabbit Brain
Authors: Suleiman Suleiman A. , Spector Reynold 
Published: October 2006

Abstract:The development and regional distribution of methionine synthetase (EC 2.1.1.13) in rabbit brain was determined. In adult rabbits, the specific activity (units per milligram protein) of methionine synthetase in cortex, cerebellum, brain stem, and corpus striatum was comparable to the specific activity in whole brain (0.5 units/mg). In the first few weeks of life, the specific activity of methionine synthetase in whole rabbit brain declined from a value of 1.1 units/mg at 1 day of age to 0.5 units/mg at 6–10 weeks. Two‐year‐old rabbits had 0.6 units/mg in whole brain. These results show that: (a) methionine synthetase is distributed widely in mammalian brain and (b) methionine synthetase activity in brain declines relatively little with development.
Quantitative Relationships of Five Putative Neurotransmitter Receptor Sites in Rat Hippocampal Formation
Authors: Salvaterra Paul , Matthews Dee Ann , Foders Renée 
Published: October 2006

Abstract:The hippocampus is well suited for studies of the interrelationships of various neurotransmitter systems in the CNS by reason of its simple laminated organization, defined connections, and variety of identified neurotransmitters. We have studied the biochemical and pharmacological properties of five radiolabeled ligand binding sites in a membrane fraction prepared from rat hippocampal formation. These binding sites are thought to identify recognition sites for neurotransmitter receptors. The rank order of ligand binding sites is [3H]muscimol > [3H]quinuclidinyl benzilate > [3Hdihydroergocryptine > [3H]dihydroalprenolol > 125I‐labeled α‐bungarotoxin. All ligands have a single, saturable, high‐affinity binding site. Pharmacological characterization of the ligand binding sites indicates properties consistent with the identification of these sites as neurotransmitter receptors.
Effect of Wallerian Degeneration on Histamine Concentration of the Peripheral Nerve
Authors: MacDonald S. M. , Mezei M. , Mezei C. 
Published: October 2006

Abstract:One sciatic nerve of a White Leghorn hen was severed and the distal portion was allowed to undergo Wallerian degeneration. The change in histamine and DNA concentration and mast cell number was measured at different times following nerve sectioning in the proximal regenerating, distal degenerating, and intact, contralateral nerves. The experimental results revealed a significant accumulation of histamine in the proximal desheathed segment and in the contralateral “functional nerve,” whereas the biogenic amine in the distal desheathed nerve significantly decreased. The pattern of change of histamine in the distal and proximal nerve sheaths was different: it dropped at 2 h and then rose in the later stages of Wallerian degeneration. In the distal desheathed nerves and in both the proximal and distal nerve sheaths DNA increased significantly by 14 days. The number of mast cells appeared to be highest in the 14‐day distal nerve and in the 7‐day proximal nerve sheaths. These results support a dual localization of histamine in the peripheral nerve, and are consistent with the interpretation that the amine has either some role in neurotransmission or in the process of growth and regeneration.
Mammalian Brain Alkaline Phosphatase: Expression of Liver/Bone/Kidney Locus Comparison of Fetal and Adult Activities
Authors: Goldstein D. J. , Harris Harry 
Published: October 2006

Abstract:The alkaline phosphatases (EC 3.1.3.1) are determined by at least three gene loci, which can be sharply distinguished one from another by their sensitivity to inhibition with various amino acids and peptides and by ther‐mostability. Alkaline phosphatase is present in the brains of guinea pig, rat, mouse, hamster, squirrel, rabbit, cat, sheep, cow, tamarin, baboon, and man. The gene locus coding for alkaline phosphatase in all these brains is the liver/ bone/kidney locus, as indicated by thermostability studies and by inhibition studies with L‐phenylalanine, L‐homoarginine, and L‐phenylalanylglycylglycine. The average brain alkaline phosphatase activity is about 35% of the average for the livers and only 7.2% and 4.4% of the average kidney and placental activities, respectively. During growth and development, brain alkaline phosphatase activity decreases in the mammals studied. The amount of change is tissue‐ and species‐dependent.
Calcium Transport by Primary Cultured Neuronal and Glial Cells from Chick Embryo Brain
Authors: Barnes Eugene M. , Mandel P. 
Published: October 2006

Abstract:The uptake of calcium was examined in primary cultures of pure neurons and of glial cells from dissociated hemispheres of chick embryo brain. Neuronal cultures took up calcium at a rate of 2.0 nmol per min per mg cell protein at medium concentrations of 1.2 mM‐Ca2+ and 5.4 mM‐K+. The rate of calcium entry into neurons was increased 2.7‐fold by elevating medium potassium to 60 MM. The effect of high external potassium was to increase the Vmax value for calcium transport from 5.5 to 13 nmol per min per mg; the Michaelis constant for calcium, 1.2 mM, was unchanged. The potassium‐dependent component of calcium entry into the neuronal cultures was eliminated by addition of 0.1 mM‐D‐600 (a verapamil derivative) or by 1 mM‐CoCl2, but 0.5 μM‐tet‐rodotoxin had no significant effect. When choline replaced potassium in uptake medium no change in calcium transport was detected in neurons, nor was the entry of calcium increased when choline replaced sodium. Glial cultures took up calcium at 20% of the basal rate for neuronal cultures on a weight‐of‐protein basis. Uptake was not increased by potassium; during depolarization by potassium the calcium transport activity of glia was less than 10% that of neurons. It was concluded that cultured neurons contain a depolarization‐sensitive, calcium‐specific channel. A similar calcium transport activity was not detected in cultured glial cells.
Tyrosine Hydroxylase Activation and Inactivation by Protein Phosphorylation Conditions
Authors: Vrana Kent E. , Allhiser Carin L. , Roskoski Robert 
Published: October 2006

Abstract:Tyrosine hydroxylase, the rate‐limiting enzyme in catecholamine biosynthesis, catalyzes the conversion of tyrosine to DOPA. Cyclic AMP‐dependent protein phosphorylation conditions alter tyrosine hydroxylase activity in rat striatal homogenates. In agreement with other laboratories, we find that short‐term pre‐incubation (3 min) of extracts under phosphorylating conditions (Mg. ATP, cAMP) increases enzyme activity two‐ to tenfold over control as measured during a subsequent 15‐min assay. We now report that pre‐incubation under phosphorylating conditions for longer periods (30 min) results in a loss of activity to levels equal to or below that of the control enzyme. Addition of purified bovine brain protein kinase catalytic subunit and Mg. ATP enhances activation and increases the rate of inactivation. To demonstrate that inactivation is not associated with proteolytic degradation or irreversible de‐naturation, the inactivated form of the enzyme can be reactivated. The protein kinase inhibitor protein decreases the activation process and prevents inactivation of the enzyme to below control values. The sedimentation coefficient is not changed by phosphorylation conditions (S = 8.8 ± 0.1). Although the apparent Km, of the enzyme for the 6‐methyltetrahydropterine (6‐MPH4) cofactor is reduced (0.86 mM, control; 0.32 MM, activated), it is also reduced in the inactivated form (0.38 mM). The Ki, for dopamine is increased from 4.5 μM for the control to 28 μM for the activated enzyme, whereas the inactivated form of the enzyme exhibits a Ki of 10 μM. Removal of catecholamines by gel filtration fails to alter activity and the apparent cofactor Km. Moreover, both the activated and the inactivated states persist following gel filtration. It therefore appears that the activation‐inactivation process is not mediated solely by the modulation of enzyme feedback inhibition or changes in the Km, for 6‐MPH4. We also describe a coupled decarboxylase assay in which labeled dopamine is resolved from the precursors tyrosine and DOPA by low‐voltage paper electrophoresis.
Identification and Distribution of m‐ and p‐Hydroxyphenylacetic Acids in the Brain of the Rat
Authors: Durden David A. , Boulton Alan A. 
Published: October 2006

Abstract:The m and p isomers of hydroxyphenylacetic acid have been identified and quantitated in whole rat brain and in several regions using a capillary column high resolution gas chromatography–mass spectrometry procedure. Their concentrations were: for m‐hydroxyphenylacetic acid (mean ± S.E., number of determinations in parentheses)—whole brain, 2.3 ± 0.3 ng/g (7); hypothalamus, 1.2 ± 0.3 ng/g (5); caudate nucleus, 5.5 ± 0.6 ng/g (5); brain stem, 1.8 ± 0.1 ngig (5); cerebellum, 1.2 ± 0.1 ng/g (5) and the “rest,” 1.7 ± 0.1 ng/g (5); and for p‐hydroxyphenylacetic acid–whole brain, 10.6 ± 0.7 ng/g (7); hypothalamus, 4.5 ± 0.1 ng/g (4); caudate nucleus, 28.3 ±1.6 ng/g (5); brain stem, 8.6 ± 0.6 ng/g (5); cerebellum, 8.1 ± 0.4 ng/g (9, and the “rest,” 5.3 ± 0.5 ng/g (5). This heterogeneous distribution parallels closely that exhibited by their respective precursor amines, m‐ and p‐tyramine.
Characterization and Comparison of Neurofilament Proteins from Rat and Mouse CNS
Authors: Brown Beverly A. , Nixon Ralph A. , Strocchi Paola , Marotta Charles A. 
Published: October 2006

Abstract:Rat and mouse CNS neurofilament proteins (NFPs) were characterized and compared, in terms of electrophoretic properties on polyacrylamide gels and by peptide mapping, with one another and with other co‐purifying lower‐molecular‐weight CNS proteins, including α and β tubulin. NFPs were partially purified by modification of the axon flotation procedure of Norton and co‐workers and were demyelinated with Triton X‐100. On one‐dimensional SDS polyacrylamide gels the molecular weights of the triad of NFPs from both rat and mouse were approximately 200,000, 140,000, and 70,000. Prominent lower‐molecular‐weight proteins (63,000‐16,000) as well as minor amounts of tubulin and actin were observed after gel electrophoresis. On two‐dimensional gels (isoelectric focusing followed by SDS gel electrophoresis) each of the NFPs appeared to be composed of more than one component and the corresponding NFPs from rat and mouse had similar isoelectric points. Gel electrophoresis peptide mapping using Staphylococcus aureus V8 protease indicated the following: (1) the triad of NFPs of different sizes have different peptide maps; (2) α and β tubulin have nonidentical digestion products, which are dissimilar to those of the NFPs; (3) other proteins that co‐purify by the axon flotation procedure also have nonidentical peptide maps; and (4) the corresponding NFPs from rat and mouse have similar peptide maps. The co‐purifying proteins examined in detail (63,000–49,000) do not appear to be derived by proteolytic cleavage of NFPs and may represent other cytoskeletal constituents.
In Vitro and In Vivo Binding of S‐Adenosyl‐L‐Homocysteine to Membranes from Rat Cerebral Cortex
Authors: Fonlupt P. , Rey C. , Pacheco H. 
Published: October 2006

Abstract:Membranes from rat cerebral cortex are able to bind S‐adenosyl‐L‐homocysteine (SAH) with a KD of 5. 10‐7 M and n of 170 pmol/g fresh tissue (i.e. 20 mg protein). The binding is enhanced by Mg2+ and Ca2‐ but not K+ and Na+, γ‐Aminobutyric acid, diazepine, noradrenaline and a antagonists are without any effect; S‐adenosyl‐L‐methionine, adenosine and adenosine triphosphate inhibit SAH binding. Linkage with an adenosine receptor has not been expressly demonstrated by our method. SAH binding proteins are more abundant in the crude synaptosomal pellet (P2). A similar fixation seems to occur on brain membranes after [3H]SAH administration to rat. The binding might be linked to a methylase activity or an adenosine receptor.
Optimal Conditions for [3H]Apomorphine Binding and Anomalous Equilibrium Binding of [3H]Apomorphine and [3H]Spiperone to Rat Striatal Membranes: Involvement of Surface Phenomena Versus Multiple Binding Sites
Authors: Leysen Josée E. , Gommeren Walter 
Published: October 2006

Abstract:I. Binding of [3H]apomorphine to dopaminergic receptors in rat striatum was most reproducible and clearly detectable when incubations were run at 25°C in Tris‐HCl buffer, pH 7.5, containing 1 mM‐EDTA and 0.01% ascorbic acid, using a washed total‐membrane fraction. The receptor binding was stereospecifically inhibited by (+)‐butaclamol, and dopamine agonists and antagonists showed high binding affinity for these sites. Unlabelled apomorphine inhibited an additional nonstereospecific binding site, which was unrelated to dopamine receptors. EDTA in the incubation mixture considerably lowered nonstereospecific [3H]apomorphine binding, apparently by preventing the complexation of the catechol moiety with metal ions which were demonstrated in membrane preparations. Stereospecific [3H]apomorphine binding was not detectable in the frontal cortex, whereas in the absence of EDTA much saturable nonstereospecific binding occurred. II. Kinetic patterns of stereospecific [3H]spiperone and [3H] apomorphine binding to rat striatal membranes and the inhibition patterns of a dopamine antagonist and an agonist were evaluated at different temperatures in high‐ionic‐strength Tris buffer with salts added and low‐ionic‐strength Tris buffer with EDTA. Apparent KD, values of spiperone decreased with decreasing tissue concentrations. KD, values of both spiperone and apomorphine were little influenced by temperature changes. Scatchard plots of the stereospecific binding changed from linear to curved; the amount of nonstereospecific binding of the 3H ligands varied considerably, but in opposite directions for spiperone and apomorphine in the different buffers. In various assay conditions, interactions between agonists, and between antagonists, appeared fully competitive, but agonist‐antagonist interactions were of mixed type. The anomalous binding patterns are interpreted in terms of surface phenomena occurring upon reactions of a ligand with complex physicochemical properties and nonsolubilized sites on membranes suspended in a buffered aqueous solution. It is concluded that anomalous binding patterns are not necessarily an indication of binding to multiple sites or involvement of distinct receptors for high‐affinity agonist and antagonist binding.