bluuebunny/crossref_metadata_2025_split huggingface dataset:
Drosophila uses two distinct neuropeptide amidating enzymes, dPAL1 and dPAL2
Authors: Han Mei , Park Dongkook , Vanderzalm Pamela J. , Mains Richard E. , Eipper Betty A. , Taghert Paul H. 
Published: June 2004

AbstractNeuropeptide α‐amidation is a common C‐terminal modification of secretory peptides, frequently required for biological activity. In mammals, amidation is catalyzed by the sequential actions of two enzymes [peptidylglycine‐α‐hydroxylating monooxygenase (PHM) and peptidyl‐α‐hydroxyglycine α‐amidating lyase (PAL)] that are co‐synthesized within a single bifunctional precursor. The Drosophila genome predicts expression of one monofunctional PHM gene and two monofunctional PAL genes. Drosophila PHM encodes an active enzyme that is required for peptide amidation in vivo. Here we initiate studies of the two Drosophila PAL genes. dPAL1 has two predicted transmembrane domains, whereas dPAL2 is predicted to be soluble and secreted. dPAL2 expressed in heterologous cells is secreted readily and co‐localized with hormone. In contrast, dPAL1 is secreted poorly, even when expressed with a cleaved signal replacing the predicted transmembrane domains; the majority of dPAL1 stays in the endoplasmic reticulum. Both proteins display PAL enzymatic activity. Compared to the catalytic core of rat PAL, the two Drosophila lyases have higher Km values, higher pH optima and similarly broad divalent metal ion requirements. Antibodies to dPAL1 and dPAL2 reveal co‐expression in many identified neuroendocrine neurons. Although dPAL1 is broadly expressed, dPAL2 is found in only a limited subset of neurons. dPAL1 expression is highly correlated with the non‐amidated peptide proctolin. Tissue immunostaining demonstrates that dPAL1 is largely localized to the cell soma, whereas dPAL2 is distributed throughout neuronal processes.
Kainate receptor agonists and antagonists mediate tolerance to kainic acid and reduce high‐affinity GTPase activity in young, but not aged, rat hippocampus
Authors: Hesp Blair R. , Wrightson Timothy , Mullaney Ian , Kerr D. Steven 
Published: June 2004

AbstractDomoic acid acts at both kainic acid (KA) and α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionate (AMPA)‐sensitive glutamate receptors and induces tolerance against subsequent domoic acid insult in young but not aged rat hippocampus. To determine the receptor specificity of this effect, tolerance induction was examined in hippocampal slices from young and aged rats. Slices were preconditioned by exposure to low‐dose KA to activate kainate receptors, or the AMPA‐receptor selective agonist (S)‐5‐fluorowillardiine (FW), and following washout, tolerance induction was assessed by administration of high concentrations of KA or FW (respectively). FW preconditioning failed to induce tolerance to subsequent FW challenges, while KA‐preconditioned slices were significantly resistant to the effects of high‐dose KA. KA preconditioning failed to induce tolerance in aged CA1. Given the lasting nature of the tolerance effect, we examined G‐protein‐coupled receptor function. A number of ionotropic KA receptor agonists and antagonists significantly reduced constitutive GTPase activity in hippocampal membranes from young but not aged rats. Furthermore, in young CA1, low concentrations of the AMPA/KA blocker GYKI‐52466 also induced tolerance to high‐dose KA. Our findings suggest that tolerance is triggered by a selective reduction in constitutive KA‐sensitive G‐protein activity, and that this potential neuroprotective mechanism is lost with age.
Mapping spatio‐temporal activation of Notch signaling during neurogenesis and gliogenesis in the developing mouse brain
Authors: Tokunaga Akinori , Kohyama Jun , Yoshida Tetsu , Nakao Keiko , Sawamoto Kazunobu , Okano Hideyuki 
Published: June 2004

AbstractNotch1 plays various important roles including the maintenance of the stem cell state as well as the promotion of glial fates in mammalian CNS development. However, because of the very low amount of the activated form of Notch1 present in vivo, its precise activation pattern has remained unknown. In this study, we mapped the active state of this signaling pathway in situ in the developing mouse brain using a specific antibody that recognizes the processed form of the intracellular domain of Notch1 cleaved by presenilin/γ‐secretase activity. By using this antibody, active state of Notch1 came to be detectable with a higher sensitivity than using conventional antibody against Notch1. We found that activated Notch1 was mainly detected in the nuclei of a subpopulation of radial glial cells, the majority of proliferating precursor cells in the ventricular zone (VZ). However, Notch1 activation was not detected in neuronal precursor cells positive for neuronal basic helix‐loop‐helix proteins or in differentiating neurons in the embryonic forebrain. Interestingly, we found that Notch1 was transiently activated in the astrocytic lineage during perinatal CNS development. Taken together, the present method has enabled us to determine the timing, gradients, and boundaries of the activation of Notch signaling.
In vivo characterization of somatodendritic dopamine release in the substantia nigra of 6‐hydroxydopamine‐lesioned rats
Authors: Sarre Sophie , Yuan Hong , Jonkers Nadine , Van Hemelrijck An , Ebinger Guy , Michotte Yvette 
Published: June 2004

AbstractWe investigated the effect of an injection of 6‐hydroxydopamine (6‐OHDA) into the rat medial forebrain bundle (MFB) on the degeneration and the function of the dopaminergic cell bodies in the substantia nigra (SN) 3 and 5 weeks after lesioning. After injection of 6‐OHDA into the MFB a complete loss of dopamine content was apparent in the striatum 3 weeks after lesioning. In the SN the amount of tyrosine hydroxylase‐immunoreactive dopamine cells decreased gradually, with a near‐complete lesion (> 90%) obtained only after 5 weeks, indicating that neurodegeneration of the nigral cells was still ongoing when total dopamine denervation of the striatum had already been achieved. Baseline dialysate and extracellular dopamine levels in the SN, as determined by in vivo microdialysis, were not altered by the lesion. A combination of compensatory changes of the remaining neurones and dopamine originating from the ventral tegmental area may maintain extracellular dopamine at near‐normal levels. In both intact and lesioned rats, the somatodendritic release was about 60% tetrodotoxin (TTX) dependent. Possibly two pools contribute to the basal dopamine levels in the SN: a fast sodium channel‐dependent portion and a TTX‐insensitive one originating from diffusion of dopamine. Amphetamine‐evoked dopamine release and release after injection of the selective dopamine reuptake blocker GBR 12909 were attenuated after a near‐complete denervation of the SN (5 weeks after lesioning). So, despite a 90% dopamine cell loss in the SN 5 weeks after an MFB lesion, extracellular dopamine levels in the SN are kept at near‐normal levels. However, the response to a pharmacological challenge is severely disrupted.
The synaptophysin/synaptobrevin complex dissociates independently of neuroexocytosis
Authors: Reisinger Clemens , Yelamanchili Sowmya V. , Hinz Britta , Mitter Diana , Becher Anja , Bigalke Hans , Ahnert‐Hilger Gudrun 
Published: June 2004

AbstractSynaptophysin is one of the most abundant membrane proteins of small synaptic vesicles. In mature nerve terminals it forms a complex with the vesicular membrane protein synaptobrevin, which appears to modulate synaptobrevin's interaction with the plasma membrane‐associated proteins syntaxin and SNAP25 to form the SNARE complex as a prerequisite for membrane fusion. Here we show that synaptobrevin is preferentially cleaved by tetanus toxin while bound to synaptophysin or when existing as a homodimer. The synaptophysin/synaptobrevin complex is, however, not affected when neuronal secretion is blocked by botulinum A toxin which cleaves SNAP25. Excessive stimulation with α‐latrotoxin or Ca2+‐ionophores dissociates the synaptophysin/synaptobrevin complex and increases the interaction of the other SNARE proteins. The stimulation‐induced dissociation of the synaptophysin/synaptobrevin complex is not inhibited by pre‐incubating neurones with botulinum A toxin, but depends on extracellular calcium. However, the synaptophysin/synaptobrevin complex cannot be directly dissociated by calcium alone or in combination with magnesium. The dissociation of synaptobrevin from synaptophysin appears to precede its interaction with the other SNARE proteins and does not depend on the final fusion event. This finding further supports the modulatory role the synaptophysin/synaptobrevin complex may play in mature neurones.
Long‐term regulation of signalling components of adenylyl cyclase and mitogen‐activated protein kinase in the pre‐frontal cortex of human opiate addicts
Authors: Ferrer‐Alcón M. , J. García‐Fuster M. , La Harpe R , García‐Sevilla J. A. 
Published: June 2004

AbstractOpiate addiction involves the development of chronic adaptive changes in µ‐opioid receptors and associated pathways (e.g. cAMP signalling) which lead to neuronal plasticity in the brain. This study assessed the status of cAMP and mitogen‐activated protein kinase (MAPK) pathways in brains (pre‐frontal cortex) of chronic opiate addicts. In these subjects (n = 24), the immunodensities of adenylyl cyclase‐I, PKA Cα, total and phosphorylated CREB were not different from those in sex‐, age‐ and PMD‐matched controls. Moreover, the ratio pCREB/tCREB was similar in opiate addicts (0.74) and controls (0.76), further indicating that opiate addiction in humans is not associated with an upregulation of several key components of cAMP signalling in the pre‐frontal cortex. In contrast, the components of MAPK cascade (Ras/c‐Raf‐1/MEK/ERK) were decreased in the same brains. Notably, pronounced downregulations of phosphorylated MEK (85%) and ERK1/2 (pERK1: 81%; pERK2: 80%) were quantitated in brains of opiate addicts. Chronic morphine treatment in rats (10–100 mg/kg for 5 days) was also associated with decreases of pERK1/2 (59–68%) in the cortex. In SH‐SY5Y cells, morphine also stimulated the activity of pERK1/2 (2.5‐fold) and the MEK inhibitor PD98059 blocked this effect (90%). The abnormalities of MAPK signalling might have important consequences in the long term development of various forms of neural plasticity associated with opiate addiction in humans.
Differential effects of Rho GTPases on axonal and dendritic development in hippocampal neurones
Authors: Ahnert‐Hilger G. , Höltje M. , Große G. , Pickert G. , Mucke C. , Nixdorf‐Bergweiler B. , Boquet P. , Hofmann F. , Just I. 
Published: June 2004

AbstractFormation of neurites and their differentiation into axons and dendrites requires precisely controlled changes in the cytoskeleton. While small GTPases of the Rho family appear to be involved in this regulation, it is still unclear how Rho function affects axonal and dendritic growth during development. Using hippocampal neurones at defined states of differentiation, we have dissected the function of RhoA in axonal and dendritic growth. Expression of a dominant negative RhoA variant inhibited axonal growth, whereas dendritic growth was promoted. The opposite phenotype was observed when a constitutively active RhoA variant was expressed. Inactivation of Rho by C3‐catalysed ADP‐ribosylation using C3 isoforms (Clostridium limosum, C3lim or Staphylococcus aureus, C3stau2), diminished axonal branching. By contrast, extracellularly applied nanomolar concentrations of C3 from C. botulinum (C3bot) or enzymatically dead C3bot significantly increased axon growth and axon branching. Taken together, axonal development requires activation of RhoA, whereas dendritic development benefits from its inactivation. However, extracellular application of enzymatically active or dead C3bot exclusively promotes axonal growth and branching suggesting a novel neurotrophic function of C3 that is independent from its enzymatic activity.
Different activation of NF‐κB by stimulation of dopamine D2L and D2S receptors through calcineurin activation
Authors: Takeuchi Yusuke , Fukunaga Kohji 
Published: June 2004

AbstractDopamine D2 receptor (D2R) has known to activate Ca2+/calmodulin‐dependent protein phosphatase, calcineurin by increasing in the intracellular Ca2+. We previously showed that D2LR (long isoform) and D2SR (short isoform) enhanced SRE and NF‐κB, and conversely suppressed CRE transcriptional activities in NG108‐15 cells stably expressed with these receptors (NGD2LR and NGD2SR). In this study, to investigate whether activation of calcineurin is involved in the transcriptional regulations through D2R, we evaluated effect of cyclosporin A, a selective calcineurin inhibitor, on them in NGD2LR and NGD2SR cells using luciferase reporter gene assay. We first confirmed that D2LR activates calcineurin in NG108‐15 cells by measurement of dephosphorylation of dopamine‐ and cyclic AMP‐regulated phosphoprotein Mr 32 000 (DARPP‐32) at threonin 34 by immunoblot analysis with its phospho‐specific antibody. Cyclosporin A treatment showed no change in suppression of forskolin‐induced CRE activation or activation of SRE but significantly attenuated NF‐κB activation by D2LR stimulation in NGD2LR cells. Interestingly, D2SR‐induced NF‐κB activation, which was weaker than that by D2LR stimulation, was not affected by cyclosporin A treatment in NGD2SR cells. Furthermore, D2SR stimulation did not cause dephosphorylation of DARPP‐32 at threonin 34. Taken together, D2SR and D2LR may employ different signaling pathway on intracellular Ca2+ mobilization, thereby showing different NF‐κB activation in the calcineurin‐dependent manner.
Oral administration of Crataegus flavonoids protects against ischemia/reperfusion brain damage in gerbils
Authors: Zhang De‐Liang , Zhang Yue‐Ting , Yin Jun‐Jie , Zhao Bao‐Lu 
Published: June 2004

AbstractStroke is the third leading cause of death as dementia is a main symptom of Alzheimer's disease. One of the important mechanisms in the pathogeny of stroke is free radical production during the reperfusion period, therefore the effects of a type of natural antioxidant, i.e. Crataegus flavonoids (CF), on brain ischemic insults were investigated in Mongolian gerbil stroke model. Results showed that pretreatment of the animals with CF decreased reactive oxygen species (ROS) production, thiobarbituric acid reactive substances content, and nitrite/nitrate concentration in brain homogenate, increased the brain homogenate‐associated antioxidant level in a dose‐dependent manner. CF pretreatment increased the amount of biologically available NO by scavenging of superoxide anion produced during reperfusion. At same time, in the process of ischemia/reperfusion brain damage, the content of nitrite/nitrate (the end product of NO) increased, and of NO detected by ESR decreased. Oral pretreatment with CF decreased the nitrite/nitrate content in the brain homogenate and increased the biologically available NO concentration in a dose‐dependent manner. The increasing effect of antioxidant on NO might be due to its scavenging effect on superoxide anion, which could react with NO into peroxynitrite. iNOS was implied in delayed neuron death after brain ischemic damage and it was found that pretreatment with CF could decrease the protein level of tumor necrosis factor (TNF)‐α and nuclear factor‐kappa B (NF‐κB), and increase the mRNA level of NOS estimated by western blotting and RT‐PCR. More neurons survived and fewer cells suffered apoptosis in the hippocampal CA1 region of CF treated animal brain. These results suggest that oral administration of this antioxidant increases the antioxidant level in the brain and protects the brain against delayed cell death caused by ischemia/reperfusion injury.
The brefeldin A‐inhibited GDP/GTP exchange factor 2, a protein involved in vesicular trafficking, interacts with the β subunits of the GABAA receptors
Authors: Charych Erik I. , Yu Wendou , Miralles Celia P. , Serwanski David R. , Li Xuejing , Rubio Maria , De Blas Angel L. 
Published: June 2004

AbstractWe have found that the brefeldin A‐inhibited GDP/GTP exchange factor 2 (BIG2) interacts with the β subunits of the γ‐aminobutyric acid type‐A receptor (GABAAR). BIG2 is a Sec7 domain‐containing guanine nucleotide exchange factor known to be involved in vesicular and protein trafficking. The interaction between the 110 amino acid C‐terminal fragment of BIG2 and the large intracellular loop of the GABAAR β subunits was revealed with a yeast two‐hybrid assay. The native BIG2 and GABAARs interact in the brain since both coprecipitated from detergent extracts with either anti‐GABAAR or anti‐BIG2 antibodies. In transfected human embryonic kidney cell line 293 cells, BIG2 promotes the exit of GABAARs from endoplasmic reticulum. Double label immunofluorescence of cultured hippocampal neurons and electron microscopy immunocytochemistry of rat brain tissue show that BIG2 concentrates in the trans‐Golgi network. BIG2 is also present in vesicle‐like structures in the dendritic cytoplasm, sometimes colocalizing with GABAARs. BIG2 is present in both inhibitory GABAergic synapses that contain GABAARs and in asymmetric excitatory synapses. The results are consistent with the hypotheses that the interaction of BIG2 with the GABAAR β subunits plays a role in the exocytosis and trafficking of assembled GABAAR to the cell surface.
Striatal GDNF administration increases tyrosine hydroxylase phosphorylation in the rat striatum and substantia nigra
Authors: Salvatore Michael F. , Zhang Jin‐Lu , Large Delia M. , Wilson Patsy E. , Gash Clelland R. , Thomas Theresa Currier , Haycock John W. , Bing Guoying , Stanford John A. , Gash Don M. , Gerhardt Greg A. 
Published: June 2004

AbstractGlial cell line‐derived neurotrophic factor (GDNF) improves motor dysfunction associated with aging in rats and non‐human primates, in animal models of Parkinson's disease, and may improve motoric function in patients with advanced Parkinson's disease. These improvements are associated with increased dopamine function in the nigrostriatal system, but the molecular events associated with this increase are unknown. In these studies, 100 µg of GDNF was injected into the striatum of normal aged (24‐month‐old) male Fischer 344 rats. The protein levels and phosphorylation of TH, ERK1/2, and related proteins were determined by blot‐immunolabeling of striatum and substantia nigra harvested 30 days after injection. In GDNF‐treated rats, TH phosphorylation at Ser31 increased ∼40% in striatum and ∼250% in the substantia nigra. In the substantia nigra, there was a significant increase in ERK1 phosphorylation. In striatum, there was a significant increase in ERK2 phosphorylation. Microdialysis studies in striatum showed that both amphetamine‐ and potassium‐evoked dopamine release in GDNF recipients were significantly increased. These data show that GDNF‐induced increases in dopamine function are associated with a sustained increase in TH phosphorylation at Ser31, which is greatest in the substantia nigra and maintained for at least one month following a single striatal administration of GDNF. These findings, taken from the nigrostriatal system of normal aged rats, may help explain the long lasting effects of GDNF on dopamine function and prior studies supporting that a major effect of GDNF involves its effects on dopamine storage and somatodendritic release of dopamine in the substantia nigra.
Functional and Cognitive Consequences of Silent Stroke Discovered Using Brain Magnetic Resonance Imaging in an Elderly Population
Authors: Schmidt Wolf‐Peter , Roesler Andreas , Kretzschmar Konrad , Ladwig Karl‐Heinz , Junker Ralf , Berger Klaus 
Published: June 2004

Objectives: To evaluate the prevalence of silent stroke and its associated consequences on physical, cognitive, and emotional functioning in an elderly population.Design: Population‐based cross‐sectional survey.Setting: The Memory and Morbidity in Augsburg Elderly project in the Augsburg region of southern Germany.Participants: Two hundred sixty‐seven community‐dwelling persons aged 65 to 83.Measurements: The presence of silent stroke was determined using magnetic resonance imaging brain scan and a single question asking for physician‐diagnosed stroke in each participant. The health effect of silent stroke was assessed using rating scales for self‐perceived health status (36‐item short‐form health survey), activities of daily living (ADLs) and instrumental ADLs, cognitive function, and depression (Center for Epidemiologic Studies Depression scale).Results: Just fewer than 13% (12.7%) of participants were affected by silent stroke. Silent stroke was associated with a history of hypertension, heart surgery, and elevated C‐reactive protein. Individuals with silent stroke showed impairments on the Mini‐Mental State Examination test and in the cognitive domains of memory, procedural speed, and motor performance.Conclusion: The presence of silent stroke has a considerable effect on cognitive performance in those affected. Determining the presence of silent stroke using brain imaging may contribute to identifying individuals at risk for developing gradual neurological deficits.
Physician Recognition of Cognitive Impairment: Evaluating the Need for Improvement
Authors: Chodosh Joshua , Petitti Diana B. , Elliott Marc , Hays Ron D. , Crooks Valerie C. , Reuben David B. , Galen Buckwalter J. , Wenger Neil 
Published: June 2004

Objectives: To assess physician recognition of dementia and cognitive impairment, compare recognition with documentation, and identify physician and patient factors associated with recognition.Design: Survey of physicians and review of medical records.Setting: Health maintenance organization in southern California.Participants: Seven hundred twenty‐nine physicians who provided care for women participating in a cohort study of memory (Women's Memory Study).Measurements: Percentage of patients with dementia or cognitive impairment (using the Telephone Interview of Cognitive Status supplemented by the Telephone Dementia Questionnaire) recognized by physicians. Relationship between physician recognition and patient characteristics and physician demographics, practice characteristics, training, knowledge, and attitudes about dementia.Results: Physicians (n=365) correctly identified 81% of patients with dementia and 44% of patients with cognitive impairment without definite dementia. Medical records documented cognitive impairment in 83% of patients with dementia and 26% of patients with cognitive impairment without definite dementia. In a multivariable model, physicians with geriatric credentials (defined as geriatric fellowship experience and/or the certificate of added qualifications) recognized cognitive impairment more often than did those without (risk ratio (RR)=1.56, 95% confidence interval (CI)=1.04–1.66). Physicians were more likely to recognize cognitive impairment in patients with a history of depression treatment (RR=1.3, 95% CI=1.03–1.45) or stroke (RR=1.37, 95% CI=1.04–1.45) and less likely to recognize impairment in patients with cognitive impairment without definite dementia than in those with dementia (RR=0.46, 95% CI=0.23–0.72) and in patients with a prior hospitalization for myocardial infarction (RR=0.37, 95% CI=0.09–0.88) or cancer (RR=0.49, 95% CI=0.18–0.90).Conclusion: Medical record documentation reflects physician recognition of dementia, yet physicians are aware of, but have not documented, many patients with milder cognitive impairment. Physicians are unaware of cognitive impairment in more than 40% of their cognitively impaired patients. Additional geriatrics training may promote recognition, but systems solutions are needed to improve recognition critical to provision of emerging therapies for early dementia.