bluuebunny/crossref_metadata_2025_split huggingface dataset:
Platelet activating factor‐induced apoptosis is inhibited by ectopic expression of the platelet activating factor G‐protein coupled receptor
Authors: Brewer Cynthia , Bonin Fanny , Bullock Paula , Nault Marie‐Christine , Morin Jennifer , Imbeault Sophie , Shen T. Y. , Franks D. J. , Bennett Steffany A. L. 
Published: March 2003

AbstractThe pro‐inflammatory lipid mediator platelet activating factor (PAF: 1‐O‐alkyl‐2‐acetyl‐sn‐glycero‐3‐phosphocholine) accumulates in ischemia, epilepsy, and human immunodeficiency virus‐1‐associated dementia and is implicated in neuronal loss. The present study was undertaken to establish a role for its G‐protein coupled receptor in regulating neurotoxicity. PC12 cells do not express PAF receptor mRNA as demonstrated by northern analysis and RT‐PCR. In the absence of the G‐protein coupled receptor, PAF (0.1−1 µm) triggered chromatin condensation, DNA strand breaks, oligonucleosomal fragmentation, and nuclear disintegration characteristic of apoptosis. Lyso‐PAF (0.001–1 µm), the immediate metabolite of PAF, did not elicit apoptotic death. Concentrations of PAF or lyso‐PAF that exceeded critical micelle concentration had physicochemical effects on plasma membrane resulting in necrosis. Apoptosis but not necrosis was inhibited by the PAF antagonist BN52021 (1–100 µm) but not CV3988 (0.2–20 µm). Ectopic PAF receptor expression protected PC12 transfectants from ligand‐induced apoptosis. PAF receptor‐mediated protection was inhibited by CV3988 (1 µm). These data provide empirical evidence that: (i) PAF can initiate apoptosis independently of its G‐protein coupled receptor; (ii) PAF signaling initiated by its G‐protein coupled receptor is cytoprotective to PC12 cells; (iii) the pro‐ and anti‐apoptotic effects of PAF on PC12 cells can be pharmacologically distinguished using two different PAF antagonists.
Role of blood–brain barrier organic anion transporter 3 (OAT3) in the efflux of indoxyl sulfate, a uremic toxin: its involvement in neurotransmitter metabolite clearance from the brain
Authors: Ohtsuki Sumio , Asaba Hiroshi , Takanaga Hitomi , Deguchi Tsuneo , Hosoya Ken‐ichi , Otagiri Masaki , Terasaki Tetsuya 
Published: March 2003

AbstractRenal impairment is associated with CNS dysfunctions and the accumulation of uremic toxins, such as indoxyl sulfate, in blood. To evaluate the relevance of indoxyl sulfate to CNS dysfunctions, we investigated the brain‐to‐blood transport of indoxyl sulfate at the blood–brain barrier (BBB) using the Brain Efflux Index method. [3H]Indoxyl sulfate undergoes efflux transport with an efflux transport rate of 1.08 × 10−2/min, and the process is saturable with a Km of 298 µm. This process is inhibited by para‐aminohippuric acid, probenecid, benzylpenicillin, cimetidine and uremic toxinins, such as hippuric acidand 3‐carboxy‐4‐methyl‐5‐propyl‐2‐furanpropanoic acid. RT–PCR revealed that an OAT3 mRNA is expressed in conditionally immortalized rat brain capillary endothelial cell lines and rat brain capillary fraction. Xenopus oocytes expressing OAT3 were found to exhibit [3H]indoxyl sulfate uptake, which was significantly inhibited by neurotransmitter metabolites, such as homovanillic acid and 3‐methoxy‐4‐hydroxymandelic acid, and by acyclovir, cefazolin, baclofen, 6‐mercaptopurine, benzoic acid, and ketoprofen. These results suggest that OAT3 mediates the brain‐to‐blood transport of indoxyl sulfate, and is also involved in the efflux transport of neurotransmitter metabolites and drugs. Therefore, inhibition of the brain‐to‐blood transport involving OAT3 would occur in uremia and lead to the accumulation of neurotransmitter metabolites and drugs in the brain.
Brief, repeated exposure to substrates down‐regulates dopamine transporter function in Xenopus oocytes in vitro and rat dorsal striatum in vivo
Authors: Gulley Joshua M. , Doolen Suzanne , Zahniser Nancy R. 
Published: March 2003

AbstractIn heterologous expression systems, dopamine transporter (DAT) cell‐surface localization is reduced after relatively prolonged exposure to d‐amphetamine (AMPH) or dopamine (DA), suggesting a role for substrate‐mediated regulation of transporter function. Here, we investigated whether brief, repeated periods of substrate exposure modulated transporter function, first, in an in vitro model system and, second, in intact rat brain. In human DAT‐expressing Xenopus laevis oocytes, repeated exposure to low micromolar concentrations of DA, AMPH or tyramine markedly reduced transport‐mediated currents. This functional down‐regulation was attenuated by inclusion of a protein kinase C (PKC) inhibitor and probably reflects DAT redistribution, as cell‐surface [3H]WIN 35 428 binding was significantly lower following DA exposure. High‐speed chronoamperometry was used to measure clearance of exogenously applied DA in dorsal striatum (STR) and nucleus accumbens (NAc) of anesthetized rats. In STR, frequent (every 2 min) applications of DA altered DA clearance parameters in a manner consistent with profound down‐regulation of DAT function. Similar changes were not observed in NAc or after repeated vehicle (ascorbic acid) application. Together, our results suggest that brief, repeated periods of substrate exposure lead to rapid down‐regulation of DAT activity and that this type of regulation can occur in vivo in STR, but not NAc.
Role of PKC and MAPK in cytosolic PLA2 phosphorylation and arachadonic acid release in primary murine astrocytes
Authors: Xu Jianfeng , Weng Yu‐I. , Simoni Agnes , Krugh Brent W. , Liao Zhongji , Weisman Gary A. , Sun Grace Y. 
Published: March 2003

AbstractAlthough Group IV cytosolic phospholipase A2 (cPLA2) in astrocytes has been implicated in a number of neurodegenerative diseases, mechanisms leading to its activation and release of arachidonic acid (AA) have not been clearly elucidated. In primary murine astrocytes, phorbol myristate acetate (PMA) and ATP stimulated phosphorylation of ERK1/2 and cPLA2 as well as evoked AA release. However, complete inhibition of phospho‐ERK by U0126, an inhibitor of mitogen‐activated protein kinase kinase (MEK), did not completely inhibit PMA‐stimulated cPLA2 and AA release. Epidermal growth factor (EGF) also stimulated phosphorylation of ERK1/2 and cPLA2[largely through a protein kinase C (PKC)‐independent pathway], but EGF did not evoke AA release. These results suggest that phosphorylation of cPLA2 due to phospho‐ERK is not sufficient to evoke AA release. However, complete inhibition of ATP‐induced cPLA2 phosphorylation and AA release was observed when astrocytes were treated with GF109203x, a general PKC inhibitor, together with U0126, indicating the important role for both PKC and ERK in mediating the ATP‐induced AA response. There is evidence that PMA and ATP stimulated AA release through different PKC isoforms in astrocytes. In agreement with the sensitivity of PMA‐induced responses to PKC down‐regulation, prolonged treatment with PMA resulted in down‐regulation of PKCα and ε in these cells. Furthermore, PMA but not ATP stimulated rapid translocation of PKCα from cytosol to membranes. Together, our results provided evidence for an important role of PKC in mediating cPLA2 phosphorylation and AA release in astrocytes through both ERK1/2‐dependent and ERK1/2‐independent pathways.
Selective reduction of a PDZ protein, SAP‐97, in the prefrontal cortex of patients with chronic schizophrenia
Authors: Toyooka Kazuhiko , Iritani Shuji , Makifuchi Takao , Shirakawa Osamu , Kitamura Noboru , Maeda Kiyoshi , Nakamura Ryosuke , Niizato Kazuhiro , Watanabe Masahiko , Kakita Akiyoshi , Takahashi Hitoshi , Someya Toshiyuki , Nawa Hiroyuki 
Published: March 2003

AbstractMany postsynaptic density proteins carrying postsynaptic density‐95/discs large/zone occludens‐1 (PDZ) domain(s) interact with glutamate receptors to control receptor dynamics and synaptic plasticity. Here we examined the expression of PDZ proteins, synapse‐associated protein (SAP) 97, postsynaptic density (PSD)‐95, chapsyn‐110, GRIP1 and SAP102, in post‐mortem brains of schizophrenic patients and control subjects, and evaluated their contribution to schizophrenic pathology. Among these PDZ proteins, SAP97 exhibited the most marked change: SAP97 protein levels were decreased to less than half that of the control levels specifically in the prefrontal cortex of schizophrenic patients. In parallel, its binding partner, GluR1, similarly decreased in the same brain region. The correlation between SAP97 and GluR1 levels in control subjects was, however, altered in schizophrenic patients. SAP102 levels were also significantly reduced in the hippocampus of schizophrenic patients, but this reduction was correlated with sample storage time and post‐mortem interval. There were no changes in the levels of the other PDZ proteins in any of the regions examined. In addition, neuroleptic treatment failed to mimic the SAP97 change. These findings suggest that a phenotypic loss of SAP97 is associated with the postsynaptic impairment in prefrontal excitatory circuits of schizophrenic patients.
Assembly of tau in transgenic animals expressing P301L tau: alteration of phosphorylation and solubility
Authors: Sahara Naruhiko , Lewis Jada , DeTure Michael , McGowan Eileen , Dickson Dennis W. , Hutton Mike , Yen Shu‐Hui 
Published: March 2003

AbstractTransgenic mice (JNPL3), which develop neurofibrillary degeneration and express four‐repeat human tau with P301L missense mutation, were characterized biochemically to determine whether the development of aggregated tau from soluble tau involves an intermediate stage. Homogenates from mice of different ages were separated into buffer‐soluble (S1), sarkosyl‐ and salt‐extractable (S2) and sarkosyl‐insoluble pellet (P3) fractions, and analyzed for human tau distribution, phosphorylation and filament formation. S1 and S2 fractions contained 50–60‐kDa tau whereas the S2 fraction also had 64‐kDa tau. The level of tau in the P3 fraction increased in an age‐dependent manner and correlated positively with the soluble tau concentration. The P3 fraction from 2.5–6.5‐month‐old mice contained 64‐ and 50–60‐kDa tau, whereas that from 8.5‐month and older transgenic animals contained mostly 64‐kDa and higher molecular weight tau. The S2 and P3 fractions contained comparable amounts of 64‐kDa tau. The 64‐kDa tau was predominantly human, and phosphorylated at multiple sites: Thr181, Ser202/Thr205, Thr212, Thr231, Ser262, Ser396/Ser404, Ser409 and Ser422. Most of these sites were phosphorylated to a lesser extent in S2 than in P3 fractions. Tau polymers were detected in P3 fractions from 3‐month and older female JNPL3 mice, but not in non‐transgenic controls. The results suggest that tau in S2 represents an intermediate from which insoluble tau is derived, and that phosphorylation may play a role in filament formation and/or stabilization.
Participation of protein kinase C α isoform and extracellular signal‐regulated kinase in neurite outgrowth of GT1 hypothalamic neurons
Authors: Choe Youngshik , Lee Byung Ju , Kim Kyungjin 
Published: March 2003

AbstractIn the present study, we investigated the selective role of protein kinase C (PKC) isoforms on neurite outgrowth of the GT1 hypothalamic neurons using several PKC isoform‐selective inhibitors and transfection‐based expression of enhanced green fluorescence protein (EGFP)‐fused PKC isoforms. 12‐O‐Tetradecanoylphorbol‐13‐acetate (TPA) induced neurite outgrowth and growth cone formation, effects that were blocked by GF 109203X (a PKC inhibitor), safingolTM(a PKCα‐selective inhibitor), but not by rottlerinTM (a PKCδ‐selective inhibitor), indicating that PKCα may be selectively involved in neurite outgrowth and cytoskeletal changes of filamentous actin and β‐tubulin. To define the differential localization of PKC isoforms, EGFP‐tagged PKCα, PKCγ, and PKCδ were transfected into GT1 neuronal cells. TPA treatment induced relocalization of PKCα‐EGFP to growth cones and cell–cell adhesion sites, PKCγ‐EGFP to the nucleus, and PKCδ‐EGFP to the membrane ruffle, respectively. An EGFP chimera of the catalytic domain of PKCα (PKCα‐Cat‐EGFP), the expression of which was inducible by doxycycline, was employed to directly ascertain the effect of PKCα enzymatic activity on neurite outgrowth of GT1 cells. Transient transfection of PKCα‐Cat‐EGFP alone increased the neurite‐outgrowth and doxycycline treatment further augmented the number of neurite‐containing cells. We also examined the involvement of the extracellular signal‐regulated kinase (ERK) MAP kinase in TPA‐induced neurite outgrowth. TPA treatment increased phosphorylated ERK MAP kinase, but not p38 MAP kinase. Specific inhibition of PKCα with safingol blocked the phosphorylation of ERK induced by TPA. More importantly, both neurite outgrowth and phosphorylation of ERK by TPA were blocked by PD 098059, a specific inhibitor of MEK (MAP kinase/ERK kinase‐1), but not by SB203580, a specific inhibitor of p38 MAP kinase. These results demonstrate that PKCα isoform‐specific activation is involved in neurite outgrowth of GT1 hypothalamic neuronal cells via ERK, but not the p38 MAP kinase signal pathway.
Dose‐dependent protective effect of selenium in rat model of Parkinson's disease: neurobehavioral and neurochemical evidences
Authors: Zafar Khan Shoeb , Siddiqui Almas , Sayeed Iqbal , Ahmad Muzamil , Salim Sofian , Islam Fakhrul 
Published: March 2003

AbstractNormal cellular metabolism produces oxidants that are neutralized within cells by antioxidant enzymes and other antioxidants. An imbalance between oxidant and antioxidant has been postulated to lead the degeneration of dopaminergic neurons in Parkinson's disease. In this study, we examined whether selenium, an antioxidant, can prevent or slowdown neuronal injury in a 6‐hydroxydopamine (6‐OHDA) model of Parkinsonism. Rats were pre‐treated with sodium selenite (0.1, 0.2 and 0.3 mg/kg body weight) for 7 days. On day 8, 2 µL 6‐OHDA (12.5 µg in 0.2% ascorbic acid in normal saline) was infused in the right striatum. Two weeks after 6‐OHDA infusion, rats were tested for neurobehavioral activity, and were killed after 3 weeks of 6‐OHDA infusion for the estimation of glutathione peroxidase, glutathione‐S‐transferase, glutathione reductase, glutathione content, lipid peroxidation, and dopamine and its metabolites. Selenium was found to be successful in upregulating the antioxidant status and lowering the dopamine loss, and functional recovery returned close to the baseline dose‐dependently. This study revealed that selenium, which is an essential part of our diet, may be helpful in slowing down the progression of neurodegeneration in parkinsonism.
Transmitter uptake and release in PC12 cells overexpressing plasma membrane monoamine transporters
Authors: Schonn Jean‐Sébastien , Desnos Claire , Henry Jean‐Pierre , Darchen François 
Published: March 2003

AbstractTransmitter uptake and exocytosis of secretory vesicles are two essential aspects of neurotransmission. Here we show that transient overexpression of plasma membrane monoamine transporters in rat pheochromocytoma PC12 cells induced an approximate 20‐fold enhancement of cellular uptake of monoamines. Intravesicular amine concentration was greatly increased, as demonstrated directly by carbon fibre amperometry. However, the amount of stored monoamines diminished over a 5‐h period, unless monoamine oxidase was inhibited, indicating that monoamines leak out from secretory vesicles. This efflux of monoamines accounts for the reported dependence of vesicular monoamine content (the quantal size) on the kinetics of vesicular monoamine uptake. Measuring radiolabelled monoamines release from the cell population provided accurate determination of the secretory activity of the subpopulation (10–20%) of cells transfected with monoamine transporters, since they contained about 95% of the radiolabel. Accordingly, significant modification of the secretory responses was observed, at the cell population level, upon transient expression of the serotonin transporter and of proteins known to interfere with exocytosis, such as botulinum neurotoxin C1, GTPase‐deficient Rab3 proteins, truncated Rabphilin constructs or Rim. The co‐transfection assay described here, based on transient expression of monoamine transporters, should prove useful in functional studies of the secretory machinery.
Ceramide increases mitochondrial free calcium levels via caspase 8 and Bid: role in initiation of cell death
Authors: Darios Frédéric , Lambeng Nathalie , Troadec Jean‐Denis , Michel Patrick P. , Ruberg Merle 
Published: March 2003

AbstractWe investigated how the mitochondrial phase of ceramide‐mediated cell death is initiated in nerve growth factor (NGF)‐differentiated PC12 cells. We distinguished three independent effects of ceramide: free radical production; a transient increase in cytosolic free calcium; and a long‐lasting increase in mitochondrial free calcium. Only the latter led to cell death, which could be prevented by buffering of mitochondrial calcium with the calcium binding protein calbindin D‐28K ectopically expressed in mitochondria. We showed that mitochondrial calcium did not increase as a result of the increase in cytosolic free calcium levels. Rather, it appears to derive from the endoplasmic reticulum (ER) since dantrolene, which inhibits release of calcium from ER into cytosol through ryanodine receptors, prevented the increase in cytosolic free calcium but potentiated the increase in mitochondrial free calcium. This suggests that a transfer of calcium occurs directly, or very locally, between the two organelles. This transfer implicated activation of caspase 8 and cleavage of its substrate Bid, a previously unknown function of these cell death intermediaries. The increase in mitochondrial free calcium was also responsible for the release of cytochrome c into the cytosol, underlining the critical role it plays in ceramide‐mediated cell death.
Dopamine‐dependent responses to cocaine depend on corticotropin‐releasing factor receptor subtypes
Authors: Lu Lin , Liu Zhiyuan , Huang Mingsheng , Zhang Zhangying 
Published: March 2003

AbstractThe effects on locomotor response to cocaine challenge, acquisition of cocaine conditioned place preference and cocaine‐induced dopamine (DA) release in nucleus accumbens and ventral tegmental area by the non‐specific corticotropin‐releasing factor (CRF) receptors antagonist α‐helical CRF, the selective CRF receptor subtype 1 antagonist CP‐154,526 and the selective CRF receptor subtype 2 antagonist anti‐sauvagine‐30 (AS‐30) were investigated in rats. Both α‐helical CRF (10 µg, i.c.v.) and CP‐154,526 (3 µg, i.c.v.) decreased the cocaine‐induced distance travelled, whereas AS‐30 (3 µg, i.c.v.) did not show such an effect. The CRF receptor antagonists also have significant effects on stereotype counts induced by cocaine injection, in which the α‐helical CRF or CP‐154,526 but not AS‐30 did significantly reduce the stereotype counts. α‐Helical CRF (10 µg) prior to each injection of cocaine blocked cocaine conditioned place preference with no significant difference observed in the time spent in the drug‐paired side between post‐ and pre‐training and both 1 and 3 µg CP‐154,526 also had significant inhibitory effects on cocaine‐induced place preference. However, pre‐treatment with an i.c.v. infusion of AS‐30 (1 or 3 µg) prior to each injection of cocaine did not affect the acquisition of conditioned place preference. The α‐helical CRF and CP‐154,526 reduced extracellular DA levels of nucleus accumbens and ventral tegmental area in response to the injection of cocaine. However, both α‐helical CRF and CP‐154,526 did not modify extracellular DA levels under basal conditions. In contrast, the i.c.v. infusion of AS‐30 had no effects on either the basal DA or the cocaine‐induced increase in DA release in nucleus accumbens and ventral tegmental area. These findings demonstrate that activation of the CRF receptor is involved in behavioral and neurochemical effects of cocaine challenge and cocaine reward and that the role of CRF receptor subtypes 1 and 2 in cocaine‐induced locomotion, reward and DA release is not identical. The CRF receptor subtype 1 is largely responsible for the action of the CRF system on cocaine locomotion and reward. These results suggest that the CRF receptor antagonist, particularly the CRF receptor subtype 1 antagonist, might be of some value in the treatment of cocaine addiction and cocaine‐related behavioral disorders.
An education programme for individuals with Parkinson’s disease
Authors: Sunvisson Helena , Ekman Sirkka‐Liisa , Hagberg Hjördis , Lökk Johan 
Published: March 2003

An education programme for individuals with Parkinson’s disease People with Parkinson’s disease (PD) have to face a lot of ongoing sickness – depending on limitations in daily life and society. Ability for optimal living demands knowledge about the sickness, medications, side‐effects and knowledge about the best way to go on living with PD. In this study, 43 persons with PD participated in an outpatient programme based on the structure of connection model. The programme consisted of two weekly 2‐h sessions for 5 weeks. Each session consisted of 1 h of dialogue and 1 h of physical performance. The two teachers in the programme were registered nurse and registered physiotherapist. The programme was evaluated with focus on participants’ psychosocial situation, mobility and activity in daily living. Participating in the programme gave these individuals an improved psychosocial situation and improved mobility pattern. However, these improvements were not transferred to habitual daily life, which suggests that task‐oriented training provides the best solution.
Struggling to be/show oneself valuable and worthy to get care
Authors: Strandberg Gunilla , Åström Gunilla , Norberg Astrid 
Published: March 2003

Struggling to be/show oneself valuable and worthy to get care. One aspect of the meaning of being dependent on care – a study of one patient, his wife and two of his professional nurses Dependency on care has commonly been described negatively and as a problem that needs to be addressed. From a larger data material, interviews with an old, hospitalized man with a chronic disease, his wife and two of his professional nurses was selected to study. The aim was to illuminate the meaning of being dependent on care, when it appears `negative'. A phenomenological‐hermeneutic approach was used to interpret the material. The interpretation shows that dependency on care is reluctantly shown although it is expected to be expressed and/or respected as it is shown. This makes dependency on care camouflaged and the space to be dependent is limited. The meaning of being dependent on care is understood as a two‐dimensional struggle for existence. One dimension of the struggle is about to be/show oneself worthy to get care, as dependency on care holds a fear to be abandoned. The other dimension of the struggle is about to be/show oneself valuable as a human being, as identity is built upon being able to manage oneself and be strong. The interpretation if reflected on can open up possibilities to improve the quality of life for patients who are dependent on care.