bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expression of myelin proteolipid and basic protein mRNAS in cultured cells
Authors: Macklin W.B. , Weill C.L. , Deininger P.L. 
Published: January 2005

AbstractStudies were undertaken to investigate the regulation of myelin‐specific mRNA expression in cultured cells. Three experimental systems were investigated: primary oligodendrocytes grown as enriched cell populations, primary oligodendrocytes grown in the presence of chick spinal cord neurons, and C6 cells. cDNA probes specific for the myelin proteolipid mRNA and the myelin basic protein mRNA were used to quantitate proteolipid and myelin basic protein mRNA levels in cells under different experimental conditions. C6 cells expressed less than 0.2% of the proteolipid mRNA that was expressed in primary oligodendrocytes. Primary oligodendrocytes expressed the myelin‐specific mRNAs for at least 104 days in culture, and the level of these mRNAs in cultures was elevated fourfold by coculturing rat oligodendrocytes with chick spinal cord neurons.
Long‐chain acyl‐coenzyme a synthetase in rat brain myelin
Authors: Vaswani K. K. , Ledeen R. W. 
Published: January 2005

AbstractLong‐chain acyl‐CoA synthetase (EC 6.2.1.3), an enzyme(s) that activates fatty acids prior to incorporation into phospholipids and other substances, has been detected in highly purified myelin from rat brain stem. The high levels relative to microsomes (11% and 15% for oleate and arachidonate, respectively) tended to preclude contamination by the latter membrane as the source of activity. Additional evidence came from sequential purification and mixing experiments. Km values were not appreciably different for the two substrates with the two membranes, but Vmax values were approximately 2–4‐fold greater for arachidonate in both membranes. Triton X‐100 increased activity somewhat in myelin but not in microsomes; with arachidonate as substrate it reduced activity in the latter. Heat inactivation studies and pH profiles suggested the presence of two different enzymes, as previously shown for other tissues.
Translational regulation of myelin basic protein synthesis
Authors: Campagnoni A. T. , Hunkeler M. J. , Moskaitis J. E. 
Published: January 2005

AbstractSynthesis of the mouse myelin basic proteins (MBPs) was studied in reticulocyte lysates programmed with brain mRNA in the presence or absence of brain factors. Addition of brain factors to the lysates increased the incorporation of [35S] methionine into total TCA‐precipitable protein by a factor of 6–9, and the majority of this stimulation was found to be due to initiation factors. Although brain factors increased total protein synthesis, the percentage of MBP synthesis was reduced from 4.3% of the total counts incorporated (in the absence of brain factors) to 1.4% (in their presence). Increasing the concentration of brain mRNA in the lysates also reduced the relative levels of MBP synthesis. These results suggested the MBP mRNAs, as a group, were less efficiently initiated than most brain mRNAs. An analysis of the nucleotide sequence flanking the initiator codon of the MBP mRNAs indicates the presence of a second AUG codon 5 bases upstream, immediately followed by a termination codon, which may provide a structural explanation for the poorer initiation efficiency of the MBP mRNAs. Further analysis of the synthesis of the individual MBPs in the presence or absence of inhibitors of initiation (7‐methylguanosine triphosphate and aurintricarboxylic acid) and elongation (anisomycin and emetine) indicated that the 14‐kD MBP mRNA was less efficiently translated than the other MBP mRNAs. Synthesis of the 14‐kD MBP was more strongly inhibited by the initiation inhibitors than the other MBP mRNAs, and synthesis of the 14‐kD MBP was increased relative to the other MBPs in the presence of elongation inhibitors. These results are consistent with the notion that the 14‐kD MBP mRNA is initiated less efficiently than the other MBP mRNAs.
Transient increase in intracellular concentration of adenosine 3′:5′‐cyclic monophosphate results in morphological and biochemical differentiation of C6 glioma cells in culture
Authors: Sharma S. K. , Raj A. B. J. 
Published: January 2005

AbstractIncubation of C6‐BU1 glioma cells in the presence of isoproterenol and Ro20‐1724—a potent cAMP phosphodiesterase inhibitor—results in a transient increase in intracellular cAMP levels, followed by a rapid efflux of cyclic AMP from the cells into the media. Two distinct types of morphological changes could be seen: (1) rounded cell bodies with multipolar processes and beadings after 30 minutes of incubation—this period coincides with a 70–80‐fold increase in intracellular cAMP levels, and (2) elongated cell bodies with extended bipolar processes after 24–48 hours. By this time the intracellular cAMP concentration drpped to a low level, which was only three‐ to four fold higher than that in control. The transient increase in intracellular cAMP concentration results in retardation of cell growth, diminished uptake of 3H‐2‐deoxyglucose, and abolition of enhanced synthesis of cyclic AMP by concanavalin A.
Monoclonal antibodies to a brain dopamine binding protein: Production, specificity, and immunohistochemistry
Authors: Hsu L. L. , Moroi K. , Lakchaura B. D. , Chan T. , Lin C.‐T. , Wu J.‐Y. 
Published: January 2005

AbstractA dopamine binding protein (DABP) has been purified from the rat brain synaptic membrane to homogeneity by afinity chromatography and gel electrophoresis. The monoclonal antibodies against the DABP were produced by the mouse‐mouse hybridoma technique and characterized for their specificity to dopamine receptors by displacement of dopamine receptor binding. These monoclonal antibodies have been used to localize DABP in rat brain by immunohistochemistry. A specific linear structure of reaction product was seen in both caudate nucleus and cerebral cortex. This finding suggests that the DABP is present in the cerebral cortex and caudate nucleus as a membranous component of the neurons or their processes.
Serotonin turnover rate in raphe and cortex of mice infected with Venezuelan equine encephalomyelitis virus
Authors: Lima L. , Walder R. , Obregón F. , Drujan B. 
Published: January 2005

AbstractThe turnover of serotonin (5HT) was determined in the raphe area and cortex of mice infected with Pixuna, a strain of intermediate virulence of Venezuelan equine encephalomyelitis virus (VEEV). NMRI‐mice, 24 days old, were inoculated intracerebrally (ic) with 300 LDS0 of the virus. The animals were sacrificed 4, 7, 15, 21, 30, and 60 days postinoculation. 5HT and 5‐hydrodryindolacetic acid (SHIAA) in raphe and cortex were determined by high performance liquid chromatography (HPLC) with electrochemical detection. Turnover rate of 5HT was determined by the administration of pargyline, p‐chlorophenylalanine, and probenecid. The content of 5HT or SHIAA and 5HT/5HIAA ratios were not significantly different in infected compared with control mice. However, a decrease of 5HT turnover rate, determined after pargyline treatment, was observed in the raphe and not in the cortex of infected mice at 4 and 7 days after the inoculation. The turnover rate/(5HT)0 in raphe is decreased in infected mice with signs of illness, suggesting a lower density of 5HT innervation in this brain area. The administration of p‐chlorophenylalanine and probenecid showed that the cortex is also affected, but the synthesis is less modified than metabolism or elimination. Cell bodies of 5HT neurons seem to be more susceptible than projections to infection by Pixuna strain of VEEV.
Dopamine receptors on isolated membranes of rat lymphocytes
Authors: Ovadia H. , Abramsky O. 
Published: January 2005

AbstractUsing [3H]‐dopamine (DA) as the ligand of choice, we have shown that rat lymphocytes possess DA binding sites. The binding of [3H]‐DA was specific, saturable, and of high affinity. The specific binding in membranes obtained from Con A‐activated lymphoblasts was greater than the binding in respective unactivated lymphoid cells, and displaced by lower concentrations of unlabeled ligand. [3H]‐DA was displaced specifically by DA, norepinephrine, and apromorphine. The binding sites were insensitive to neuroleptic drugs such as sulpiride, bromocryptine, and haloperidol. On the basis of these findings, we have suggested that lymphocytes possess a receptor site for catecholamines and the receptor for DA might be a D‐3 receptor type.
Interleukin‐1‐like immunoreactiveity in pripheral tissues
Authors: Schultzberg M. , Svenson S. B. , Unden A. , Bartfai T. 
Published: January 2005

AbstractRabbit antisera were raised against a synthetic peptide corresponding to the amino acid residues 169–194 in the murine interleukin‐1 sequences. Immunoreactive varicose fibers were observed in teh vas deferens, urinary bladder, gastrointestinal tract, and coeliacsuperior mesentric anglion complex of the rat. Fibers were also encountered around blood vessels in several organs including the thymus, spleen, lymph nodes, liver, and kidney.
Metabolism of cholesterol and triacylglycerol in cultured chick neuronal cells, glial cells, and fibroblasts: Accumulation of esterified cholesterol in serum‐free culture
Authors: Saito M. , Benson E. P. , Saito M. , Rosenberg A. 
Published: January 2005

AbstractMetabolism of free and esterfied cholesterol and triacylglycerol was compard in cultured neuronal cells, glial cells, and fibroblasts grown from chick embryos. Cellular contents of free and esterified cholesterol were comparable in these cells and triactlglycerol content in the neuronal cells was about 40% of that in the other cell types. Cholesterol synthesis from [3H]acetate was high in all these cells and was not affected by fetal calf serum in the culture medium. Monensin, which has been shown to influence cholesterol metabolism through the inhibition of low‐density liporprotein receptor recycling in human fibroblasts, did not induce profound effects on cholesterol metabolism in these cells. Higher incorporation of [3H] oleic acid into esterified cholesterol was observed in the glial cells and fibroblasts when fetal calf serum was removed from the culture medium. Cellular content of the esterified cholesterol also increased in the glial cells under a serum‐free arrangement. 25‐Hydroxy‐cholesterol induced higher incorporation of both [3H]acetic acid and [3H]oleic acid into esterified cholesterol in all of these cells. The results indicate that the active metabolism of cholesterol found in cultured chick neural cells and fibroblasts may not be regulated by and LDL receptor‐mediated system and some factors in fetal calf serum inhibit cellular accumulation of esterified cholesterol.
Angiotensin‐converting enzyme associated with Torpedo californica electric organ membranes
Authors: Altstein M. , Dudai Y. , Vogel Z. 
Published: January 2005

AbstractTorpedo electric organ contains high concentrations of angiotensin converting enzyme (ACE) like activity, cleaving [Leu5]enkephalin at the Gly3‐Phe4 peptide bond. Most of the activity cosediments with the cell membranes. The enzymatic preparation from membranes is inhibited by low concentrations of the ACE inhibitors, AQ 14225 and SQ 20881 (IC50 of 0.6 and 15 nM, respectively), and is weakly inhibited by the neutral endopeptidase inhibitors, phosphoramidon and thiorphan (IC50 of 30 μM and ca. 70 nM, respectively). The enzyme degrades hippuryl‐His‐Leu and is activated by NaCl. Hippuryl‐His‐Leu and [Leu5]enkephalin are degraded with Km of 93 and 41 μM, and Vmax of 21 and 10 nmol/mg protein/min, respectively. The specific activity of the ACE‐like activity in homogenates of Torpedo electric organ is relatively high (6.3 nmol hippuryl‐His‐Leu/mg protein/min); this value is similar to that obtained for rat lung and rat striatum.
Effects of Ca2+ entry blockers on kainate‐induced changes in extracellular amino acids and Ca2+ in vivo
Authors: Lazarewicz J. W. , Lehmann A. , Hamberger A. 
Published: January 2005

AbstractThe effect of organic Ca2+ channel blockers and Co2+ on kainate‐induced in 45Ca2+ efflux and amino acid release was studied in the rabbit hippocampus with the dialysis‐perfusion technique. Administration of 1 mM kainate caused a transient, 50% drop of extracellular Ca2+. This effect was insensitive to 100 μM flunarizine or verapamil, 10 μM nimodipine, and 6 mM CoCl2. The organic Ca2+ entry blockers did not significantly influence kainate‐induced changes in extracellular amino acid, whereas Ca2+ affected both basal and kainic acid stimulated release of amino acids. These results indicate that kainate‐regulated Ca2+ ionophores differ from Ca2+ channels in peripheral tissues in terms of sensitivity to Ca2+ entry inhibitors.
Quisqualate‐sensitive, chloride‐dependent transport of glutamate into rat brain synaptosomes
Authors: Zaczek R. , Balm M. , Arlis S. , Drucker H. , Coyle J. T. 
Published: January 2005

AbstractA chloride‐dependent transport process for glutamate has been identified in partially purified rat brain synaptosomes. This process shares many characteristics with the chloride‐dependent sequestration process for glutamate in brain sonicates, which was previously thought to represent a quisqualate receptor, such as sensitivity to specific inhibitors and regulation by anions. Increases the concentrations of chloride led to and increase in the apparent Vmax without affecting the KT. Synaptosomes preincubated with [3H]‐L‐glutamate exhibit an efflux of the radiolabel, which was stimulated by a substrate for the carrier in the incubating medium, indicating the bidirectional nature of the transport. The chloride‐dependent transfer process is restricted to the brain, and regional and developmental profiles clearly distinguish it from the sodium‐dependent high‐affinity uptake process for glutamate. Nevertheless, the effects of excitotoxic lesions strongly suggest a neuronal localization of the chloride‐dependent transport.
Spinal cord interneuron degenerative atrophy caused by peripheral nerve lesions is prevented by serotonin depletion
Authors: di Giulio A. M. , Tenconi B. , Mannavola A. , Mantegazza P. , Schiavinato A. , Gorio A. 
Published: January 2005

AbstractPeripheral nerve section causes a degenerative atrophy of substance P sensory input and of met‐enkephalin interneurons in the dorsal horn of the spinal cord. Radioimmunoassay of both peptides indicates that the decrease in peptide levels ranges from 30 to 50%, that it occurs several days after lesioning, and that it is simultaneous for the two peptides. Quantitative immunocytochemistry performed by computer‐assisted analysis of met‐enkephalin‐positive boutons shows that following sciatic nerve lesions there is a decresed density of immunoreactive boutons per unit area in densit of immunoreactive boutons per unit area in the substantia gelatinosa of the dorsal horn in the lumbar cord ipsilateral to the lesion. Within 24 h of nerve injury there is a significant and transient enhancement of serotonin turnover, as indicated by the increased levels of 5‐hydroxyindolacetic acid in the lumber cord, without any change in serotonin concentrations. The restoration of normal serotonin metabolism at d 10 postlesioning coincides with the peptidergic loss. However, if, prior to nerve resection, serotonin stores are depleted by p‐chlorophenylalanine treatment, the damage to met‐enkephalin interneurons in fully prevented, while substance P loss does still occur. These results suggest that signals caused by the section of a peripheral nerve are directly responsible for substance P loss in the spinal cord and are, presumably, rapidly transported into the CNS, causing an activation of the serotoninergic raphe neurons projecting to spinal cord. The activation of this system is likely responsible for the degenerative atrophy of the met‐enkephalin interneurons. These results further confirm our previus suggestion (Di Giulio et al: Peptides 6:24–256, 1985; Brain Res 342:405–408, 1985) that the peptidergic loss induced by perpheral nerve section may be intraspinally regulated, and that pain sensations which develop after nerve lesions may be related to intraspinal alterations, such as the atrophy of met‐enkephalin‐containing interneurons, rather than to the formation of a large neuroma by the injured axons. As a matter of fact the increased serotonin turnover is triggered within 24 h, while neuroma formation requires several days following nerve lesion.
Glycolipid sialosyltransferase activity in synaptosomes exhibits a product specificity for (2–8)disialosy lactosyl ceramide (ganglioside GD3)
Authors: Durrie R. , Saito M. , Rosenberg A. 
Published: January 2005

AbstractIntact synaptosomes prepared from 28‐day‐old rat brains were incubated with CMP‐N‐acetyl‐(14C) neuraminic acid in Krebs‐Henseleit buffer in an atmosphere of 95% O2: 5% CO2, at 37°C. The activity of CMP‐NANA: ganglioside sialosyltransferase using endogenous acceptors was 0.84 pmoles NANA transferred/mg synaptosomal protein/hr. Analysis of the distribution of labeled sialic acid revealed that GD3 ganglioside (α2→8 disialosyl, α2→3 galactosyl, β1→4 glucosyl, β1→1‐ ceramide) was the major product in the membrane carrying 32% of the total lipid bound label. Treatment of the reaction products with Clostridium neuraminidase liberated labeled sialic acid from GD3 and yielded labeled GM3, then unlabeled lactosyl ceramide. Lac‐cer and GM3 are present in small amounts in synaptosomes, and GD3 repressents less than 2% of the total ganglioside. Our findings indicate that the sialosyltransferse activity of synaptosomes exhibits a preferential product specificity for the small pool of synaptosomal membrane GD3 ganglioside that may be formed in situ, via sialosylation of its precursor (GM3 or lactosyl ceramide) which pre‐exists in the synaptosomal plasma membrane. The second major labeleld product quantitatively was GD1a whose precursor substrate, GM1, is quite abundant in the membrane, so that the conversion rat of GM1 to GD1a was low in comaprison with GD3 formation. Sialosylation of other synaptosomal membrane gangliosides was negligible.
Alterations in the adenylate cyclase‐cAMP‐phosphodiesterase system in the locus coeruleus during the development of spontaneous hypertension of the rat
Authors: Bahner U. , Schmid G. , Geiger H. , Heidland A. , Palkovits M. 
Published: January 2005

AbstractThe quantitatively most important noradrenergic cell group of the brain is the locus coreruleus. Significantly increased cAMP concentration could be measured in spontaneously hypertensive rats in comparison to normotensive Wistar‐Kyoto control rats at every stage investigated. Furthermore, both the basal activity and maximal stimulation of Ca++‐and GTP‐dependent adenylate cyclase as well as phosphodiesterase activity were significantly decreased in the spontaneously hypertensive rats at 14 weeks of age. The possible role of the locus coeruleus in spontaneous hypertension is presumed in counterrgulatory mechanisms against rising blood pressure.
Effect of acute ethanol administration on brain levels of tetrahydropapaveroline in L‐dopa‐treated rats
Authors: Cashaw J. L. , Geraghty C. A. , McLaughlin B. R. , Davis V. E. 
Published: January 2005

AbstractThe effect of ethanol on the concentration of the aberrant dopemine metabolite, tetrahydropapaveroline (THP), in brains of L‐dopa‐treated rats has been evaluated. THP was isolated from rat brain extract by a newly developed multiple stage separation technique that is highly specific for the alkaloid. THP, dopa, and dopamine were assayed by high‐performance liquid chromatography with electrochemical detection. THP was not found in brains of untreated animals. However, levels of 0.42 pmol THP per g brain were observed in animals that received L‐dopa (200 mg/kg) by intraperitoneal injection (IP) 90 min before decapitation. Administration of ethanol (3g/kg) IP to L‐dopa‐treated animals at time intervals ranging from 60 to 240 min before decapitation resulted in significant increase in brain levels of THP as compared to L‐dopa‐treated animals. Maximum levels of THP (4.02 to 4.82 pmol/g brain) were observed when ethnol was given at time intervals ranging from 80 to 180 min before the animals were killed. Administration of ethnol and L‐dopa, as compared to the administration of L‐dopa only, markedly increased brain levels of dopa and dopamine. Maximum brain levels of THP, dopa, and dopamine in animals administered ethanol plus L‐dopa as compared with L‐dopa‐treated animals repressented a 1048%, 325%, and 84% increase, respectively. These results strongly support the concept that the concentration of THP in the brain of intact animals can be enhanced by ethanol administration.
Some characteristics of muscle‐conditioned media with excitatory and inhibitory influences of neurite outgrowth from early neural tube explants
Authors: Heaten M. B. 
Published: January 2005

AbstractThis study examined the growth of basal plate explants from 40‐hr chick embryos containing the trigeminal motor nucleus in the presence of target muscle‐conditioned medium (MCM) from day‐4, day‐10, and day‐18 embroys. We had previously found that MCM derived from the 4‐day target tissue enhanced neurite outgrowth from explants, while target MCM from 10‐ and 18‐day embryos inhibited it. For the present study, target MCM was treated with trypsin to assess the nature of the active fractions, or pre‐incubated in polyornithine‐coated dishes to determine the possible in polyornithine‐coated dishes to determine the possible presence and relative contributions of substrate‐binding vs. soluble components. Both trypsinization and pre‐incubation ablished the outgrowth‐enhancing potential of the 4‐day MCM, indicating a protein or polypeptide substeate‐binding active fraction, with no appreciable active souluble component. When the 10‐day target MCM were trypsinized, the inhibitory indluence was reversedm and neurite outgrowth was enhanced. Similarly, when the MCM from these embryos was preincinated over polyornithinem the inhibitory influence was lost and was replaced by a stimulatory one. These results suggest that the 10‐ and 18‐day MCM contain an active inhibitory fraction that is a protein or polypeptide, and which binds to a positively charged substate. When this inhibitory fraction is inactivated or depleted, an excitatory soluble fraction is revealed. Such a dual nature in MCM has not been seen previously and may be expressed only when the media are assayed with very early neural tissue.