bluuebunny/crossref_metadata_2025_split huggingface dataset:
Local Cerebral Glucose Utilization in Two Models of B12 Deficiency
Authors: Hakim Antoine M. , Cooper Bernard A. , Rosenblatt David S. , Pappius Hanna M. 
Published: October 2006

Abstract:Local cerebral glucose utilization (LCGU), as measured by the 2‐deoxy‐D‐[l‐14C]glucose technique, reflects local cerebral functional activity. In an effort to elucidate mechanisms of the encephalopathy associated with deficiency of vitamin B12, LCGU was determined in two recently described models of effective B12 deficiency: exposure of rats to subanesthetic doses of nitrous oxide (N2O) and/or administration of 1‐amino‐cyclopentane‐1‐carboxylic acid (cycloleucine). Our results show that exposure of adult rats to N2O depresses LCGU selectively in cortical, auditory, and limbic structures, in association with a depression in whole‐brain activities of the vitamin B12‐dependent methyltetrahydrofolate‐homocysteine methyl‐trans‐ferase (EC 2.1.1.13, methionine synthetase). Cycloleucine has no discernible effect on LCGU in the adult rat and does not change the cerebral activity of methionine synthetase.
Regional Distribution of Homocysteine in the Mammalian Brain
Authors: Broch Ole Jacob , Ueland Per Magne 
Published: October 2006

AbstractThe regional distribution of l‐homocysteine (Hcy) was determined in brains from mouse, rat, guinea pig, and rabbit, using a sensitive radioenzymatic assay. Large interspecies variations in the Hcy content in various parts of the brain were observed, but cerebellum contained the highest amount in all species investigated. In the rat the amount of Hcy in cerebellum (6.4 nmol/g) was about sixfold higher than in most other parts of the brain, whereas in the mouse and guinea pig the amount in cerebellum (about 1 nmol/g) was only twofold higher than in the other brain regions. There was a remarkably high level of Hcy in all regions of the rabbit brain (4–10 nmol/g); the highest concentration was found in the cerebellar white matter. In this species the amount of Hcy in all brain regions examined exceeded that in the liver.
Monoclonal Antibodies to Substance P: Production, Characterization of Their Fine Specificities, and Use in Immunocytochemistry
Authors: Couraud J. Y. , Frobert Y. , Conrath M. , Renzi D. , Grassi J. , Drapeau G. , Regoli D. , Pradelies P. 
Published: October 2006

Abstract:Five hybrid clones secreting antibodies to the neuropeptide substance P have been obtained by somatic cell fusion of mouse myeloma cells with splenocytes from immunized mice of the Biozzi strain. To perform rapid and sensitive screening tests as well as to study the fine specificities of each monoclonal antibody, we developed a new enzyme immunoassay of substance P using acetylcholines‐ terase as label. All five monoclonal antibodies were directed to the C‐terminal pentapeptide of substance P, especially to the Phe7 residue. They cross‐reacted with neurokinin A and to some extent with neurokinin B but not with other non‐tachykinin mammalian peptides. One monoclonal antibody (SP 14) was used for immunocytochemical experiments in the rat spinal cord and spinal ganglion, both at the light and electron microscopic levels. A strong specific neurokinin‐like immuno eactivity was observed in cell bodies, nerve fibers, and terminals, with a very low background staining. Finally, the affinities of several analogues of substance P for SP14 manoclonal antibody were shown to be correlated with their biological activities, as measured by their hypotensive effects in vivo. These findings suggested a strong structural resemblance between the combining site of the antibody and that of the physiological substance P receptor.
Triethyllead Inhibits γ‐Aminobutyric Acid Binding to Uptake Sites in Synaptosomal Membranes
Authors: Seidman Brenda C. , Olsen R. W. , Verity M. Anthony 
Published: October 2006

AbstractTriethyllead (TEL), the active metabolite of tetraethyllead, was shown previously to inhibit selectively high‐affinity Na+‐dependent uptake of γ‐aminobutyric acid (GABA) into cerebrocortical synaptosomes. Such inhibition was not related to the Na+ gradient, Na+,K+‐ATPase activity, [Cl‐], or energy charge. We report here that TEL inhibits GABA binding to the presynaptic transporter involved in Na+‐dependent uptake. Scatchard plot analysis of Na+‐dependent [3H]GABA binding to a highly purified synaptic plasma membrane preparation revealed that 25 μM TEL reduced the Bmax by 44%, leaving the KD unchanged. This binding was reversible and predominantly involved membrane uptake sites, as characterized by pharmacological specificity to GABA ligands. Approximately 85% of specific GABA binding was considered membrane uptake site binding, as indicated by sensitivity to nipecotic acid and diaminobutyric acid, with relative insensitivity to muscimol, bicuculline methiodide, baclofen, and β‐alanine. With respect to previous data, these findings suggest that TEL inhibits Na+‐sensitive high‐affinity GABA uptake by interfering with GABA binding to its presynaptic transporter.
Monoclonal Antibodies Against Glutaraldehyde‐Conjugated Dopamine
Authors: Chagnaud Jean‐Luc , Mons Nicole , Tuffet Sophie , Grandier‐Vazeilles Xavier , Geffard Michel 
Published: October 2006

AbstractFour mice were immunized with dopamine (DA)—glutaraldehyde (G)—protein conjugates over a period of 8–10 weeks. Polyclonal antisera, obtained at various intervals, were tested using an enzyme‐linked immuno‐sorbent assay (ELISA). All had anti‐conjugated DA antibodies. As soon as good antibody affinity was detected between 10‐10 and 10‐6M, the mouse yielding the highest apparent affinity was killed, and the spleen was dissected out. Hybridomas were obtained from spleen cells fused with SP2/O/Ag myeloma cells. Supernatant culture media of hybridomas were tested for the presence of anti‐conjugated DA antibodies with the ELISA method. Selected hybridomas giving good antibody affinity and specificity were then cloned by the limiting dilution technique. The resulting supernatant culture media were again tested by ELISA. Clones that gave a high antibody affinity (10‐10‐10‐8M) for G‐conjugated DA were used for histochemical localization of DA in rat brain. G‐fixed rat brains were sectioned from the telencephalon to the mesencephalon, reduced with sodium borohydride, and prepared for peroxidase‐antiperoxidase immunocytochemistry using supernatant (diluted 1:100) or ascites fluid (diluted 1:50,000). Dense networks of very fine fibers were observed in the striatum, septum, and cortex. Numerous immunoreactive cell bodies were found in the ventral tegmental area, the substantia nigra, the hypothalamus, and the dorsal raphe. The ELISA tests and adsorption controls suggested that the monoclonal antibody allowed highly specific detection of DA in tissues.
A Dopaminergic Cell Line Variant Resistant to the Neurotoxin 1‐Methyl‐4‐Phenyl‐1,2,3,6‐Tetrahydropyridine
Authors: Denton Timothy , Howard Bruce D. 
Published: October 2006

Abstract1‐Methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) is known to cause parkinsonism by killing dopaminergic neurons; the toxic substance is a metabolite, 1‐methyl‐4‐phenylpyridinium ion (MPP+). PC12 cells, which are dopaminergic, are killed in culture by MPTP and MPP+ but at concentrations much higher than that required to kill affected neurons in vivo. However, at low concentrations (10–100 μM), MPP+ caused an increased production of lactate by PC12 cells. MPP+‐treated PC12 cells exhibited decreased mitochondrial respiration. Mitochondria from the treated cells respired normally in the presence of added succinate but not β‐hydroxybutyrate, a finding indicating that MPP+ inhibits the oxidation of some substrates selectively. MPP+ was more effective in killing the cells when glycolysis was reduced with 2‐deoxyglucose or by lowering the glucose content of the culture medium. Under these conditions, MPP+ inhibited ATP synthesis and depleted cellular stores of ATP. A PC12 variant that is even more resistant to MPTP and MPP+ than are wild‐type cells has been isolated. The MPTP‐resistant variant is also more resistant to the lethal effects of oligomycin, antimycin A, and rotenone. This variant exhibited altered lactate production and mitochondrial respiration. It is suggested that some brain neurons that accumulate MPP+ without being killed by it may also have an energy metabolism somewhat different from that of more sensitive neurons.
Solubilization and Characterization of Substance P Binding Protein from Bovine Brainstem
Authors: Nakata Yoshihiro , Tanaka Hiroyasu , Morishima Yoshiyuki , Segawa Tomio 
Published: October 2006

AbstractThe specific binding protein for substance P (SP) was solubilized in an active form from the crude mitochondrial (P2) fraction of bovine brainstem. After incubation with 3–[(3‐cholamidopropyl)dimethylammonio]‐1‐propane sulfonate (CHAPS) and 0.1 M NaCl at 0°C for 30 min, the SP binding to the supernatant fraction (100,000 g, 60 min) was determined by the glass fiber filtration method reported by Bruns et al. (1983). The specific [3H]SP binding to the solubilized fraction was highly specific for SP and was displaced by nanomolar concentrations of SP and physalaemin, but only by micromolar concentrations of eledoisin. In addition, the binding was inhibited by GTP (approximately 40% of the specific binding decreased by 10 μM GTP) in both preparations. These results were virtually identical to those of P2 membrane preparations and suggested that this high‐affinity SP binding site belongs to the SP‐P type. Scatchard analyses of SP binding to the solubilized fraction revealed a single saturable component with a Bmax of 22.0 ± 5.10 fmol/mg protein and a KD of 0.79 nM, and these values are almost the same as those obtained in the P2 fraction (Bmax= 31.3 ± 3.56 fmol/mg protein, KD= 0.82 nM). Gel filtration analysis showed that the detergent‐SP binding protein complex has two calculated molecular weights of > 1,000,000 and 55,000–60,000 (a corresponding Stokes radius of 35.5 nm).
A 70‐Kilodalton Microtubule‐Associated Protein (MAP2c), Related to MAP2
Authors: Garner Craig C. , Brugg Bernard , Matus Andrew 
Published: October 2006

AbstractMicrotubule‐associated protein 2 (MAP2) from adult brain consists of a pair of high molecular mass (280 kilodaltons) polypeptides, MAP2a and MAP2b. Juvenile brain microtubules also contain a 70‐kilodalton protein that cross‐reacts with monoclonal antibodies against these high molecular weight MAP2s. We have analyzed the relationship between this 70‐kilodalton protein and MAP2 by peptide mapping. Our results show that the 70‐kilodalton species bears strong homology to the MAP2 molecules and that it is distinct from the t MAPs. We propose the name MAP2c for this low molecular weight MAP2 species. MAP2c is developmentally regulated in brain, being more abundant in neonatal tissue than in the adult. In several cell lines, MAP2c is the sole MAP2 species expressed. We examined homogenates from both juvenile brain and MAP2c‐containing cell lines for evidence of a protease activity that might be responsible for generating MAP2c from either MAP2a or MAP2b. No such activity was found, suggesting that MAP2c is an independently synthesized MAP2 species some 200 kilodaltons smaller than the previously recognized forms.
Comparison of 125I‐Angiotensin III and 125I‐Angiotensin II Binding to Rat Brain Membranes
Authors: Abhold Raymond H. , Hanesworth Jodie M. , Harding Joseph W. 
Published: October 2006

AbstractThe binding of 125I‐angiotensin III (125I‐ANG III) to rat brain membranes was examined and compared with that of 125I‐angiotensin II (125I‐ANG II). Degradation of each ligand, as monitored by HPLC, was effectively inhibited using fragments of ANG III and ANG II known to have little affinity for angiotensin binding sites. Three classes of 125I‐ANG III‐binding sites were observed based on affinity (KD= 0.13, 1.83, and 10.16 nM) and capacity (Bmax= 1.30, 18.41, and 67.2 fmol/mg protein, respectively). Two classes of 125I‐ANG II‐binding sites of high affinity (KD= 0.11 and 1.76 nM) and low capacity (Bmax= 1.03 and 18.86 fmol/mg protein, respectively) were also identified. Cross‐displacement studies confirmed that the two highest‐affinity 125I‐ANG Ill‐binding sites and the 125I‐ANG II‐binding sites were the same. On the other hand, the binding of 125I‐ANG III to the low‐affinity 125I‐ANG III‐binding site could not be inhibited with ANG II. These data imply that previously measured differences in the biological potency of cerebroventricularly applied ANG III and ANG II probably do not result from differential binding of these pep‐tides to central angiotensin receptors.
Ontogeny of Dopamine D1 Receptors in Rat Striatum
Authors: Zeng Wanyun , Hyttel John , Murrin L. Charles 
Published: October 2006

AbstractThe development of dopamine D1 receptors in rat striatum during the early postnatal period is described, using [3H]piflutixol as ligand. Dopamine D1 receptors increase in number from day of birth until about 21 days of age, when they reach adult levels. This increase in number parallels the increase in several other dopamine markers in striatum during the same time period. The increase is reflected in an increase in Bmax of ligand binding to D1 receptors. All other properties of D1 receptors that were examined do not change throughout this developmental period and are essentially the same as those found in adult tissue. These include association and dissociation rates, affinity for piflutixol as determined by kinetic and saturation studies, and pharmacology. These studies provide a biochemical and pharmacological basis for further studies on the ontogeny of dopamine receptors and of striatum and on factors regulating development of this region.
Schwann Cell Proliferation Is Accompanied by Enhanced Inositol Phospholipid Metabolism
Authors: Saunders Royal D. , DeVries George H. 
Published: October 2006

AbstractInositol phospholipid metabolism during mito‐gen‐induced Schwann cell proliferation has been examined. Addition of axolemma‐ and myelin‐enriched membrane fractions (AXL and MYE, respectively) to cultured Schwann cells stimulated 32P incorporation into phospha‐tidylinositol 4‐monophosphate [Ptdlns(4)P] and phospha‐tidylinositol4,5‐bisphosphate [Ptdlns(4,5)P2]. During the first 5 min of incubation with the mitogens, the amount of 32P incorporated into PtdIns(4)P and PtdIns(4,5)P2 was four‐ to fivefold above control values. The phosphorylation of the inositol phospholipids was dependent on the concentration of membrane mitogens and was maximal within 1 h. Schwann cells that were prelabeled with [3H]glycerol and then stimulated with AXL and MYE displayed a 30–70% increase in the amounts of [3H]PtdIns(4)P and [3H]PtdIns(4,5)P2 and a 60–80% increase in the amount of [3H]phosphatidic acid. A concomitant 20% decrease in the content of [3H]PtdIns was observed after stimulation. These results suggest that the increased metabolism of Ptdlns, Ptdlns(4)P, and Ptdlns(4,5)P2 may be one of the initial molecular events in the transduction of the mito‐genic signal across the Schwann cell plasma membrane.
Sulfhydryl Modification of Two Nicotinic Binding Sites in Mouse Brain
Authors: Stitzel Jerry A. , Campbell Stephen M. , Collins Allan C. , Marks Michael J. 
Published: October 2006

AbstractTwo distinct binding sites with properties corresponding to those expected for nicotinic cholinergic receptors can be identified in brain by the specific binding of nicotine (or acetylcholine) and α‐bungarotoxin. The effects of modification of these binding sites by treatment with the disulfide‐reducing agent dithiothreitol were examined in tissue prepared from DBA mouse brains. Treatment with dithiothreitol reduced the binding measured with either li‐gand, and reoxidization of the disulfides fully restored binding. The effects of dithiothreitol treatment appeared to be due to a reduction in the maximal binding of nicotine and to a decrease in the binding affinity for a‐bungarotoxin. Agonist affinity for the a‐bungarotoxin binding site was reduced bv treatment with low concentrations of dithiothreitol. The nicotine binding sites remaining after disulfide treatment displayed rates of ligand association and dissociation similar to those of unmodified tissue, but treatment of previously unmodified tissue with dithiothreitol accelerated the rate of nicotine dissociation. After reduction, both binding sites could be selectively alkylated with bromoacetyl‐choline. The results suggest that both putative nicotinic receptors in brain respond similarly to disulfide reduction and that their responses resemble those known for the nicotinic receptor of electric tissue.
Extracellular Amino Acid Concentrations in the Dorsal Spinal Cord of Freely Moving Rats Following Veratridine and Nociceptive Stimulation
Authors: Skilling Stephen R. , Smullin David H. , Beitz Alvin J. , Larson Alice A. 
Published: October 2006

AbstractIn vivo microdialysis was used to sample extracellular concentrations of amino acids in the dorsal lumbar spinal cord of freely moving rats. Changes in the extracellular concentrations of amino acids were measured in response to infusion of veratridine (180 μM), a sodium channel activator, as well as during acute noxious stimulation by an injection of 5% formalin into the metatarsal region of the hindleg. Veratridine produced a tetrodotoxin (TTX)‐sensitive increase in the extracellular concentration of Glu. Concentrations of Asp, taurine, Ala, Asn, and Gly were not significantly elevated following veratridine stimulation. In‐tradermal injection of formalin produced a TTX‐sensitive increase in Asp concentration and a non‐TTX‐sensitive increase in Glu concentration. These data support the hypothesis that Glu and Asp are dorsal horn neurotransmitters involved in nociception.
A Selective Increase in Particulate Superoxide Dismutase Activity in Parkinsonian Substantia Nigra
Authors: Saggu H. , Cooksey J. , Dexter D. , Wells F. R. , Lees A. , Jenner P. , Marsden C. D. 
Published: October 2006

AbstractThe total activity of superoxide dismutase (SOD) and cytosolic and particulate activity of SOD in human substantia nigra and cerebellum were measured by a spectrophotometric method based on the ability of SOD to inhibit the autoxidation of adrenaline. The cystosolic and particulate isoenzymes of SOD were differentiated by the inclusion of potassium cyanide which selectively inhibits cytosolic copper/zinc‐dependent SOD activity. In autopsied human brains, there was no difference in total SOD) activity, or the activity of SOD in cytosol in substantia nigra jof patients dying with Parkinson's disease compared to age‐matched controls. However, the activity of the particulate form of SOD was higher in the parkinsonian substantia nigra compared to control tissue. In the cerebellum there was no difference in the total, cytosolic, or particulate activity of SOD between parkinsonian patients and age‐matched controls. Increased activity of SOD in particulate fraction may be a protective response to elevated levels of toxic free radicals in the parkinsonian substantia nigra. Alternatively, increased SOD activity may induce cell death through the accumulation of hydrogen peroxide.
Glycine Potentiates the Stimulation of Inositol Phospholipid Hydrolysis by Excitatory Amino Acids in Primary Cultures of Cerebellar Neurons
Authors: Nicoletti Ferdinando , Canonico Pier Luigi 
Published: October 2006

AbstractGlycine potentiates stimulation of inositol phospholipid hydrolysis by glutamate and N‐methyl‐D‐aspartate, but not by quisqualate or carbamylcholine, in primary cultures of cerebellar granule cells. This potentiation occurs in the absence of extracellular Mg2+, but is more evident when stimulation of inositol phospholipid hydrolysis by N‐methyl‐D‐aspartate is measured in the presence of 1 mM Mg2+. The action of glycine is not antagonized by strychnine. These results suggest that glycine acts as a positive modulator of signal transduction at a specific class of N‐methyl‐D‐aspartate‐sensitive glutamate receptors coupled to inositol phospholipid hydrolysis in cerebellar granule cells.
Phosphorylation of P400 Protein by Cyclic AMP‐Dependent Protein Kinase and Ca2+/Calmodulin‐Dependent Protein Kinase II
Authors: Yamamoto Hideyuki , Maeda Nobuaki , Niinobe Michio , Miyamoto Eishichi , Mikoshiba Katsuhiko 
Published: October 2006

AbstractPurified P400 protein was phosphorylated by both purified Ca2+/calmodulin‐dependent protein kinase II (CaM kinase II) and the catalytic subunit of cyclic AMP‐dependent protein kinase (A‐kinase). Because P400 protein was suggested to function as an integral membrane protein, we investigated the phosphorylation of P400 protein using crude mitochondrial and microsomal fractions (P2/P3 fraction). Incubation of the P2/P3 fraction from mouse cerebellum with cyclic AMP or the catalytic subunit of A‐kinase stimulated the phosphorylation of P400 protein. The phosphorylation of P400 protein was not observed in the P2/P3 fraction from mouse forebrain. Cyclic AMP and A‐kinase enhanced the phosphorylation of several proteins, including P400 protein, suggesting that P400 protein is one of the best substrates for A‐kinase in the P2/ P3 fraction. Although endogenous and exogenous CaM kinase II stimulated the phosphorylation of some proteins in the P2/P3 fraction, the phosphorylation of P400 protein was weak. Immunoprecipitation with the monoclonal antibody to P400 protein confirmed that the P400 protein itself was definitely phosphorylated by the catalytic subunit of A‐kinase and CaM kinase II. A‐kinase phosphorylated only the seryl residue in P400 protein. Immunoblot analysis of the cells in primary culture of mouse cerebellum confirmed the expression of P400 protein, which migrated at the same position on sodium do‐decyl sulfate‐polyacrylamide gel electrophoresis as that in the P2/P3 fraction. Incubation of the cultured cerebellar cells with [32P]orthophosphate resulted in the labeling of P400 protein. These results suggest that P400 protein is one of the best substrates for A‐kinase and CaM kinase II in cerebellum and that the function of P400 protein is regulated by cyclic AMP‐and Ca2+/calmodulin‐dependent phosphorylation.
Monoclonal Antibody to Embryonic CNS Antigen A2B5 Provides Evidence for the Involvement of Membrane Components at Sites of Alzheimer Degeneration and Detects Sulfatides as Well as Gangliosides
Authors: Majocha Ronald E. , Jungalwala Firoze B. , Rodenrys Anne , Marotta Charles A. 
Published: October 2006

AbstractImmunohistological and biochemical studies were initiated to determine whether or not neural membrane components were associated with degenerative changes characteristic of Alzheimer's disease (AD). Monoclonal antibody A2B5, developed against embryonic chick retinal cells and previously shown to react with neural surface gangliosides, was applied to formalin‐fixed sections of control and AD brain tissue. Frontal cortex and hippocampus of AD cases exhibited high levels of A2B5 immunoreactivity within those neurons undergoing neurofibrillary degeneration. Neuritic processes associated with senile plaques were also highly reactive with the A2B5 antibody. The amount of gangliosides and their pattern after HPTLC were the same in control and AD cases. However, the unexpected observation was made that the A2B5 antibody reacted with human brain sulfatides in addition to the expected reactivity with minor gangliosides. The average level of sulfatides in AD brain was significantly higher than in normal controls. The data support the involvement of one or more membrane components with neu‐rodegeneration in the Alzheimer brain.