bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pharmacological Characterization of Rapidly Accumulated Adenosine by Dissociated Brain Cells from Adult Rat
Authors: Geiger J. D. , Johnston M. E. , Yago V. 
Published: October 2006

AbstractMechanically dissociated brain cells from adult rats were used to study biochemically and pharmacologically their capacity to accumulate rapidly [3H]adenosine. The assay, which used an inhibitor‐stop method to prevent further uptake into cells, was characterized with respect to protein and optimal substrate concentrations, and incubation times that ranged from 5 to 180 s. The accumulation of [3H]adenosine using 15‐s incubation periods, conditions under which < 10% of accumulated [3H]adenosine was metabolized, was best described kinetically by a two‐component system with Km and Vmax values for the high‐affinity component of 0.8 μM and 6.2 pmol/mg protein/15 s and for the low‐affinity component 259 μM and 2,217 pmol/mg protein/15 s, respectively. The potencies with which nucleosides, adenosine deaminase resistant adenosine receptor agonists, and nucleoside uptake inhibitors competed for these uptake components were determined. Of the nucleosides examined, adenosine was the „preferred” substrate for the uptake site. The Ki value of adenosine for the high‐affinity component was 10.7 μM. Inosine and uridine competed for a single lower affinity uptake system: Ki values were 142 and 696 μM, respectively. Nucleoside uptake inhibitors—nitrobenzylthioinosine, dipyridamole. and dilazep—were the most potent inhibitors of [3H]adenosine accumulation tested: the Ki values for the high‐affinity system were 0.11, 1.3, and 570 nM, respectively. The adenosine analogs S‐phenylisopropyladenosine, R‐phenylisopropyladenosine, and cyclohexyladenosine inhibited the high‐affinity component with Ki values of 2.3, 9.3, and 14.5 μM, respectively. N‐Ethylcarboxamidoadenosine competed for a single lower affinity uptake system; Ki, 292 μM. These results indicate that dissociated brain cells avidly take up [3H]adenosine and that the pharmacological profile for nucleoside uptake is similar to that for [3H]nitrobenzylthioinosine binding to putative nucleoside transport sites when uptake studies are conducted using brief incubation intervals.
Antioxidant Enzymes and Related Trace Elements in Aging Brain Capillaries and Choroid Plexus
Authors: Tayarani Ivan , Cloëz Isabelle , Clément Michel , Bourre Jean‐Marie 
Published: October 2006

AbstractThe activities of superoxide dismutase (SOD), glutathione peroxidase, glutathione reductase, and catalase were measured in isolated brain capillaries, choroid plexus, cerebrum, and cerebellum from rats of 2, 6, 12, and 24 months. The contents of copper, zinc, and manganese were determined in capillaries, cerebrum, and cerebellum, and the profile of fatty acids was studied in brain capillaries. In brain capillaries, the activities of glutathione peroxidase and glutathione reductase did not change with age. The activities of the two enzymes increased in cerebrum and cerebellum. In choroid plexus, glutathione peroxidase activity increased, but glutathione reductase activity remained unchanged. Catalase activity in brain capillaries declined, whereas in choroid plexus, cerebrum, and cerebellum, it did not change. The activities of the three enzymes were significantly higher in brain capillaries and choroid plexus than in cerebrum and cerebellum. SOD activity increased in the four tissues. Copper content in the capillaries increased initially and then levelled off, whereas it continued to increase in cerebrum and cerebellum. Zinc increased in brain capillaries, but did not vary in cerebrum and cerebellum. Manganese content remained constant in all tissues studied. The percent of saturated fatty‐acids in brain capillaries did not change with age, whereas those of mono‐ and polyunsaturated fatty acids increased and decreased, respectively. The possibility that a deficiency of enzymes protective against free radicals causes blood‐brain barrier and blood‐cerebrospinal fluid barrier degeneration is ruled out.
Purification and Characterisation of Cerebellins from Human and Porcine Cerebellum
Authors: Yiangou Y. , Burnet P. , Nikou G. , Chrysanthou B. J. , Bloom S. R. 
Published: October 2006

AbstractThe primary human and porcine structure of the novel neuropeptide cerebellin is unknown. These peptides were, therefore, isolated by a combination of ion‐exchange and reverse‐phase chromatography using a specific radioimmunoassay against rat cerebellin. The sequences of the peptides were deduced by mass spectrometry (for both human and porcine cerebellins) and gas‐phase Edman degradation (for porcine cerebellin). In both species, two molecular forms were identified. In the human, the major form corresponded to the pentadecamer [des‐Ser1]‐cerebellin (˜95% of the total) and the minor form, to the hexadecamer peptide. In the pig. however, both molecular forms were present in approximately equal amounts. The finding that the sequences of human and porcine cerebellin are identical to that of the rat suggests that strong evolutionary pressure has acted to conserve this sequence.
Newly Synthesized Dopamine as the Precursor for Norepinephrine Synthesis in Bovine Adrenomedullary Chromaffin Cells
Authors: Menniti Frank S. , Diliberto Emanuel J. 
Published: October 2006

AbstractThe precursor pool of dopamine for norepinephrine synthesis was investigated in cultured bovine adrenomedullary chromaffin cells incubated with [14C]tyrosine. Under conditions where the intracellular [14C]tyrosine specific activity was constant and [14C]dopamine synthesis was maximal, [14C]dopamine and [14C]norepinephrine accumulated over time, and the total intracellular dopamine content more than doubled within 120 min. When [14C]norepinephrine synthesis was calculated at different times based on the specific activity of [14C]dopamine, this rate was approximately equal to the rate of [l4C]dopamine synthesis and was, thus, inconsistent with the observed dopamine accumulation. However, the rate of [14C]norepinephrine synthesis based on the [l4C]tyrosine specific activity accounted for the dopamine accumulation, an observation suggesting that newly synthesized dopamine, i.e., dopamine with a specific activity equivalent to that of its precursor, [14C]tyrosine, is preferentially utilized for norepinephrine synthesis. Further studies showed that the subcellular distribution of [14C]dopamine was identical to that of norepinephrine and epinephrine and that the accumulated [14C]dopamine could be converted to norepinephrine within the chromaffin vesicle if dopamine uptake was blocked. Taken together, these results suggest that a small intravesicular dopamine pool, rapidly replenished by newly synthesized dopamine, serves as the substrate for dopamine β‐hydroxylase. Several mechanisms to account for this observation are discussed.
Calcium‐Dependent, Tetrodotoxin‐Sensitive Stimulation of Cortical Serotonin Release After a Tryptophan Load
Authors: Carboni E. , Cadoni C. , Tanda G. L. , Di Chiara G. 
Published: October 2006

AbstractThe effect of intraperitoneal administration of tryptophan (50, 100, or 200 mg/kg) on extracellular concentrations of tryptophan, serotonin (5‐hydroxytryptamine, 5‐HT), and 5‐hydroxyindoleacetic acid (5‐HIAA) was studied in the cortex of freely moving rats by transcerebral dialysis. Rats were implanted with dialysis probes in the frontal cortex, and experiments were performed 24 h later. Tryptophan, 5‐HT, and 5‐HIAA were quantified in 20‐min samples of dialysate by HPLC with electrochemical detection after separation on reverse‐phase columns. Tryptophan administration resulted in a significant increase of tryptophan, 5‐HT, and 5‐HIAA levels in di‐alysates. The maximal increase of 5‐HT and 5‐HIAA output was ˜ 150% over basal values. Perfusion with Ringer's solution containing tetrodotoxin (1 μM) reduced 5‐HT output by 90% and prevented the increase of 5‐HT and 5‐HIAA content after 100 mg/kg of tryptophan. Similar results were obtained after perfusion with Ringer's solution without Ca2+. The results indicate that a tryptophan load stimulates the physiological release of 5‐HT.
In Vivo Modulation of the N‐Methyl‐D‐Aspartate Receptor Complex by D‐Serine: Potentiation of Ongoing Neuronal Activity as Evidenced by Increased Cerebellar Cyclic GMP
Authors: Wood Paul L. , Emmett Mark R. , Rao Tadimeti S. , Mick Steve , Cler Julie , Iyengar Smriti 
Published: October 2006

AbstractDirect intracerebellar injections of TV‐methyl‐D‐aspartate (NMDA) or D‐serine elicited dose‐dependent increases in cerebellar cyclic GMP levels, in vivo in the mouse. The actions of D‐serine were antagonized by the competitive NMDA receptor antagonist 3‐(2‐carboxypiperazin‐4‐yl) propyl‐1‐phosphonic acid and by the phen‐cyclidine receptor agonist MK‐801, observations supporting actions at the NMDA‐coupled glycine receptor. In addition, the actions of D‐serine were antagonized by a partial agonist (D‐cycloserine) and an antagonist (HA‐966) of the NMDA‐coupled glycine receptor. These data are all consistent with D‐serine acting at the NMDA‐coupled glycine receptor and represent the first demonstration of glycine receptor potentiation of ongoing NMDA‐mediated neuronal activity in the CNS, rather than potentiation of exogenous NMDA.
An Improved HPLC‐Electrochemical Detection Method for Measuring Brain Levels of 5‐S‐Cysteinyldopamine, 5‐S‐Cysteinyl‐3,4‐Dihydroxyphenylalanine, and 5‐S‐Cysteinyl‐3,4‐Dihydroxyphenylacetic Acid
Authors: Fornstedt Bodil , Bergh Ingrid , Rosengren Evald , Carlsson Arvid 
Published: October 2006

Abstract:Brain levels of the 5‐S‐cysteinyl adducts of 3,4‐dihydroxyphenylalanine (DOPA), 3,4‐dihydroxyphenylacetic acid (DOPAC), and dopamine were determined in several mammalian species. The low levels of the compounds and the risk of artifacts during sample preparation necessitated rather profound modifications of the assaying method. The refined method has made it possible to present more accurate data than those previously reported from this laboratory. The occurrence of low levels of the 5‐S‐cysteinyl adducts in dopamine‐rich brain areas, but not in cerebellum, is indirect evidence of in vivo autoxidation of DOPA, DOPAC, and dopamine. The products generated during catechol autoxidation, including quinones and reduced forms of oxygen, are known to be potentially cytotoxic.
Diacylglycerol‐Induced Stimulation of Neurotransmitter Release from Rat Brain Striatal Synaptosomes
Authors: Davis Mary Ellen Nelson , Patrick Robert L. 
Published: October 2006

Abstract:These studies were undertaken to test the hypothesis that alterations in phosphatidylinositol metabolism can modulate neurotransmitter release in the central nervous system. The effects of 1,2‐diacylglycerols (DAGs) on dopamine release in the rat central nervous system were determined by measuring dopamine release from rat striatal synaptosomes in response to two DAGs (sn‐1,2‐dioctanoylglycerol and 1‐oleoyl‐2‐acetylglycerol) that can activate protein kinase C and one DAG (deoxydioctanoylglycerol) that does not activate this kinase. Dioctanoylglycerol and 1‐oleoyl‐2‐acetylglycerol, at a concentration of 50 μg/ml, stimulated the release of labeled dopamine from striatal synaptosomes by 35–50 and 17%, respectively. Dioctanoylglycerol‐induced release was also demonstrated for endogenous dopamine. In contrast, deoxydioctanoylglycerol (50 μg/ml) did not stimulate dopamine release. Dioctanoylglycerol‐induced dopamine release was independent of external calcium concentration, indicating a utilization of internal calcium stores. Dioctanoylglycerol (50 μg/ml) also produced a 38% increase in labeled serotonin release from striatal synaptosomes. The addition of dioctanoylglycerol to the striatal supernatant fraction increased protein kinase C activity. These results are consistent with the concept that an increase in phosphatidylinositol metabolism can stimulate neurotransmitter release in the central nervous system via an increase in DAG concentration. The data suggest an involvement of protein kinase C in the DAG‐induced release, but other sites for DAG action are also possible.
Ethanol Inhibition of N‐Methyl‐D‐Aspartate‐Stimulated Endogenous Dopamine Release from Rat Striatal Slices: Reversal by Glycine
Authors: Woodward John J. , Gonzales Rueben A. 
Published: October 2006

Abstract: N‐Methyl‐D‐aspartate stimulated a concentration‐dependent release of endogeneous dopamine from rat striatal slices. The threshold for activation was between 10 and 25 μM and reached a maximum at 1 mM. Release was completely blocked by magnesium or tetrodotoxin. Ethanol (10–200 mM) significantly inhibited the N‐methyl‐D‐aspartate‐stimulated release of dopamine by 20–45%, with half‐maximal inhibition occurring at ∼21 mM. Addition of ethanol plus increasing concentrations of magnesium resulted in a greater inhibition of N‐methyl‐D‐aspartate‐stimulated dopamine release than that observed with magnesium alone. However, this effect appeared to be due to a noninteractive additive effect of the two antagonists, as the IC50 value for magnesium inhibition was not significantly altered by ethanol. Glycine, which had no effect on dopamine release by itself, completely reversed the inhibitory effects of ethanol (25 mM) at low micromolar concentrations. These results suggest that ethanol may produce its effects in striatal slices by interfering with a glycine modulatory site of the N‐methyl‐D‐aspartate receptor‐ionophore complex.
Stimulation of Synaptosomal γ‐Aminobutyric Acid Synthesis by Glutamate and Glutamine
Authors: Battaglioli Gino , Martin David L. 
Published: October 2006

Abstract:γ‐Aminobutyric acid (GABA) synthesis was studied in rat brain synaptosomes by measuring the increase of GABA level in the presence of the GABA‐transaminase inhibitor gabaculine. The basal rate of synaptosomal GABA synthesis in glucose‐containing medium (25.9 nmol/h/mg of protein) was only 3% of the maximal activity of glutamate decarboxylase (GAD; 804 ± 83 nmol/h/mg of protein), a result indicating that synaptosomal GAD operates at only a small fraction of its catalytic capacity. Synaptosomal GABA synthesis was stimulated more than threefold by adding 500 μM glutamine. Glutamate also stimulated GABA synthesis, but the effect was smaller (1.5‐fold). These results indicate that synaptosomal GAD is not saturated by endogenous levels of its substrate, glutamate, and account for part of the unused catalytic capacity. The greater stimulation of GABA synthesis by glutamine indicates that the GAD‐containing compartment is more accessible to extrasynaptosomal glutamine than glutamate. The strong stimulation by glutamine also shows that the rates of uptake of glutamine and its conversion to glutamate can be sufficiently rapid to support GABA synthesis in nerve terminals. Synaptosomes carried out a slow net synthesis of aspartate in glucose‐containing medium (7.7 nmol/h/mg of protein). Aspartate synthesis was strongly stimulated by glutamate and glutamine, but in this case the stimulation by glutamate was greater. Thus, the larger part of synaptosomal aspartate synthesis occurs in a different compartment than does GABA synthesis.
Developmental and Regional Studies of the Metabolism of Inositol 1,4,5‐Trisphosphate in Rat Brain
Authors: Heacock Anne M. , Seguin Edward B. , Agranoff Bernard W. 
Published: October 2006

Abstract:Coupling of CNS receptors to phosphoinositide turnover has previously been found to vary with both age and brain region. To determine whether the metabolism of the second messenger inositol 1,4,5‐trisphosphate also displays such variations, activities of inositol 1,4,5‐trisphosphate 5′‐phosphatase and 3′‐kinase were measured in developing rat cerebral cortex and adult rat brain regions. The 5′‐phosphatase activity was relatively high at birth (∼50% of adult values) and increased to adult levels by 2 weeks postnatal. In contrast, the 3′‐kinase activity was low at birth and reached ∼50% of adult levels by 2 weeks postnatal. In the adult rat, activities of the 3′‐kinase were comparable in the cerebral cortex, hippocampus, and cerebellum, whereas much lower activities were found in hypothalamus and pons/medulla. The 5′‐phosphatase activities were similar in cerebral cortex, hippocampus, hypothalamus, and pons/medulla, whereas 5‐to 10‐fold higher activity was present in the cerebellum. The cerebellum is estimated to contain 50–60% of the total inositol 1,4,5‐trisphosphate 5′‐phosphatase activity present in whole adult rat brain. The localization of the enriched 5′‐phosphatase activity within the cerebellum was examined. Application of a histochemical lead‐trapping technique for phosphatase indicated a concentration of inositol 1,4,5‐trisphosphate 5′‐phosphatase activity in the cerebellar molecular layer. Further support for this conclusion was obtained from studies of Purkinje cell‐deficient mutant mice, in which a marked decrement of cerebellar 5′‐phosphatase was observed. These results suggest that the metabolic fate of inositol 1,4,5‐trisphosphate depends on both brain region and stage of development.
Toward a better understanding of the pathophysiology of OCD SSRI responders: QEEG source localization
Authors: Bolwig T. G. , Hansen E. S. , Hansen A. , Merkin H. , Prichep L. S. 
Published: September 2006

Objective:  To demonstrate the utility of three‐dimensional source localization of the scalp‐recorded electroencephalogram (EEG) for the identification of the most probable underlying brain dysfunction in patients with obsessive–compulsive disorder (OCD).Method:  Eyes‐closed resting EEG data was recorded from the scalp locations of the International 10/20 System. Variable resolution electromagnetic tomography (VARETA) was applied to artifact‐free EEG data. This mathematical algorithm estimates the source generators of EEG recorded from the scalp.Results:  An excess in the alpha range was found with sources in the corpus striatum, in the orbito‐frontal and temporo‐frontal regions in untreated OCD patients. This abnormality was seen to decrease following successful treatment with paroxetine.Conclusion:  The VARETA findings of an activation/deactivation pattern in cortical and subcortical structures in paroxetine‐responsive patients are in good accordance with data obtained in previously published positron emission tomography studies related to current hypotheses of a thalamo‐striatal‐frontal feedback loop being relevant for understanding the pathophysiology of OCD.
Relationship between IL‐1A polymorphisms and gingival overgrowth in renal transplant recipients receiving Cyclosporin A
Authors: Bostanci Nagihan , Ilgenli Tunç , Pirhan Demet Can , Clarke Fiona M. , Marcenes Wagner , Atilla Gül , Hughes Francis J. , McKay Ian J. 
Published: September 2006

AbstractAim: Levels of interleukin‐1α (IL‐1α) are elevated in periodontal inflammation. IL‐1A gene polymorphisms are associated with inflammatory diseases. This study aimed to investigate IL‐1A gene polymorphism in Cyclosporin A (CsA)‐treated renal transplant patients and investigate the association between this polymorphism and gingival crevicular fluid (GCF) levels of several cytokines.Materials and Methods: Fifty‐one renal transplant patients on CsA treatment (25 with and 26 without gingival overgrowth) and 29 healthy controls were recruited for the study. Demographic, pharmacological and periodontal parameters were recorded and gingival overgrowth was assessed.Results: Multiple regression analysis showed that genotype was significantly associated with gingival overgrowth (p=0.02). Carriage of the IL‐1A (−889) T allele was strongly protective [95% confidence interval (CI): 0.046–0.77], although not significantly associated with IL‐1α protein levels in GCF. IL‐1α, IL‐1β and IL‐8, but not IL‐6, were detected in GCF of CsA‐treated patients, but none of them was significantly associated with gingival overgrowth.Conclusions: This study is the first to associate a gene polymorphism as a risk factor for CsA‐induced gingival overgrowth in renal transplant patients, demonstrating that IL‐1A polymorphism might alter individual susceptibility to CsA. However, there was no association between GCF cytokine levels and the presence of gingival overgrowth or patient IL‐1A genotype.
CARD15 gene variants in aggressive periodontitis
Authors: Noack B. , Görgens H. , Hoffmann T. , Schackert H. K. 
Published: September 2006

AbstractObjective: The CARD15 gene encodes a protein that acts as an intracellular receptor of bacterial products, thus playing an important role in the innate immune response. Recently, CARD15 gene variants have been identified as a cause of increased susceptibility to Crohn's disease. The present study aimed to examine a potential association of CARD15 gene variants with aggressive periodontitis susceptibility.Material and Methods: The three main known CARD15 gene variants (p.R702W, p.G908R, and p.L1007fsX1008) were analysed by direct sequencing of exon 4, 8, and 11 of the gene in a total of 86 generalized aggressive periodontitis patients in comparison with 67 healthy controls.Results: The mutant allele frequencies of the CARD15 variants were low in the generalized aggressive periodontitis group as well as in the control group and not significantly different (R702W: 3.5% versus 5.2%; G908R: 1.7% versus 1.5%; L1007fsX1008: 5.2% versus 4.5%). Two rare variants (A755V and R791Q), previously described only in patients with other inflammatory diseases, were observed in three patients having aggressive periodontitis but not in controls.Conclusions: Unlike in Crohn's disease, our results did not show an association between the three main CARD15 mutations and aggressive periodontitis. The role of rare variants remains unclear.
Antibody Active Sites and Immunoglobulin Molecules
Authors: Singer S. J. , Doolittle Russell F. 
Published: October 2006

In order to obtain detailed information about the relationship between structure and function in antibody molecules, a method called affinity labeling has been devised to attach chemical labels specifically to amino acid residues in the active sites of antibody molecules. With antibodies to three different haptens, highly specific labeling of the active sites has been achieved. Tyrosine residues on both heavy and light polypeptide chains have been labeled in a molar ratio close to 2:1, and labels on the two chains are equally specific to the active sites. Peptide fragmentation studies of the labeled chains of one antibody system have shown that: (i) within 25 amino acid residues of the labeled tyrosine on either chain, substantial chemical heterogeneity exists among different antibody molecules of the same specificity; and (ii) the labeled peptide fragments from both chains are very similar in physicochemical characteristics, including average size, heterogeneity, and unusual hydrophobicity.
These experimental results have led us to the view that a particular region of the heavy chain and a particular region of the light chain are utilized to construct the active sites of the three different antibodies, differences in specificity arising from chemical perturbations in these two regions. Correlated structural studies of affinity-labeled antibodies and of the homogeneous light chains (Bence Jones proteins) and heavy chains produced in multiple myeloma may permit the identification of these special active-site regions. The view that active sites of different specificity are chemical perturbations of a particular region of the antibody molecule has a possible close analogue in enzyme systems, particularly among the esterases.
The marked chemical similarities we have observed between the active site regions of heavy and light chains indicate to us that chemical homologies, but not identities, exist between the chains. This is reinforced by recently obtained amino acid sequence data which reveal homologies between the two chains near their carboxyl-terminals. These results indicate that the structural genes which code for the synthesis of heavy and light chains are related, presumably having arisen from some common ancestral gene during evolution. This conclusion strongly suggests that both heavy and light chains determine antibody specificity, and has important implications for the still-unknown mechanisms of antibody biosynthesis.