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1.
J Psychiatr Ment Health Nurs ; 19(7): 587-93, 2012 Sep.
Article de Anglais | MEDLINE | ID: mdl-22070354

RÉSUMÉ

The immense stress associated with experiencing and surviving childhood sexual abuse directly influences coping, immune function and overall health. Lifelong overuse of maladaptive coping strategies results in impaired adjustment to stress. The purpose of this research was to re-examine if stress management education would be effective in improving coping skills for this population. Two 4-week series of stress management workshops were completed by 32 adult survivors who completed the ways of coping questionnaire before and after the training. Four categories of coping showed significant change. Stress management education is an effective and cost-efficient approach that gives adult survivors an empowering set of tools for their healing journey.


Sujet(s)
Adultes victimes de maltraitance dans l'enfance/psychologie , Violence sexuelle chez l'enfant/thérapie , Stress psychologique/thérapie , Adaptation psychologique , Adulte , Sujet âgé , Enfant , Violence sexuelle chez l'enfant/psychologie , Femelle , Humains , Adulte d'âge moyen , Soutien social , Stress psychologique/étiologie , Stress psychologique/psychologie , Jeune adulte
2.
Ecotoxicology ; 20(2): 385-96, 2011 Mar.
Article de Anglais | MEDLINE | ID: mdl-21229389

RÉSUMÉ

Silver nanoparticles have been incorporated into a wide variety of consumer products, ideally acting as antimicrobial agents. Silver exposure has long been known to cause toxic effects to a wide variety of organisms, making large scale production of silver nanoparticles a potential hazard to environmental systems. Here we describe the first evidence that an organism may be able to sense manufactured nanoparticles in a complex, environmentally relevant exposure and that the presence of nanoparticles alters the organism's behavior. We found that earthworms (Eisenia fetida) consistently avoid soils containing silver nanoparticles and AgNO(3) at similar concentrations of Ag. However, avoidance of silver nanoparticles occurred over 48 h, while avoidance of AgNO(3) was immediate. It was determined that avoidance of silver nanoparticles could not be explained by release of silver ions or any changes in microbial communities caused by the introduction of Ag. This leads us to conclude that the earthworms were in some way sensing the presence of nanoparticles over the course of a 48 h exposure and choosing to avoid exposure to them. Our results demonstrate that nanoparticle interactions with organisms may be unpredictable and that these interactions may result in ecologically significant effects on behavior at environmentally relevant concentrations.


Sujet(s)
Apprentissage par évitement , Nanoparticules métalliques/toxicité , Oligochaeta/effets des médicaments et des substances chimiques , Argent/toxicité , Polluants du sol/toxicité , Animaux , Comportement animal/effets des médicaments et des substances chimiques , Oligochaeta/physiologie , Taille de particule , Sol/composition chimique , Microbiologie du sol
3.
J S Afr Vet Assoc ; 80(4): 276-7, 2009 Dec.
Article de Anglais | MEDLINE | ID: mdl-20458874

RÉSUMÉ

We report, for the first time, an incidental finding of Calodium hepaticum infestation in a sub-adult female Cape ground squirrel (Xerus inaurus). Post mortem examination of the squirrel revealed severe haemoperitoneum, splenomegaly and hepatomegaly with miliary white spots distributed diffusely throughout the hepatic parenchyma. Histologically the portal tracts in the liver showed granulomatous inflammation with fibrosis and numerous giant cells. Occasional adult worms were identified and there were multiple C. hepaticum eggs distributed diffusely throughout the portal tracts and the parenchyma. The spleen also contained C. hepaticum eggs. The genus Rattus is the primary host and reservoir of C. hepaticum, but C. hepaticum infections have been reported previously in other Sciuridae. Based on our findings, people should be cautious of the zoonotic potential of C. hepaticum, when they come into contact with the Cape ground squirrel.


Sujet(s)
Capillaria/isolement et purification , Infections à Enoplida/médecine vétérinaire , Maladies des rongeurs/diagnostic , Sciuridae , Animaux , Réservoirs de maladies/parasitologie , Réservoirs de maladies/médecine vétérinaire , Infections à Enoplida/diagnostic , Issue fatale , Femelle , Numération des oeufs de parasites/médecine vétérinaire , Sciuridae/parasitologie
4.
Mol Pharmacol ; 73(3): 977-86, 2008 Mar.
Article de Anglais | MEDLINE | ID: mdl-18089837

RÉSUMÉ

KCNQ2 (Kv7.2) and KCNQ3 (Kv7.3) are voltage-gated K(+) channel subunits that underlie the neuronal M current. In humans, mutations in these genes lead to a rare form of neonatal epilepsy (Biervert et al., 1998; Singh et al., 1998), suggesting that KCNQ2/Q3 channels may be attractive targets for novel antiepileptic drugs. In the present study, we have identified the compound N-(6-chloro-pyridin-3-yl)-3,4-difluoro-benzamide (ICA-27243) as a selective activator of the neuronal M current and KCNQ2/Q3 channels. In SH-SY5Y human neuroblastoma cells, ICA-27243 produced membrane potential hyperpolarization that could be prevented by coadministration with the M-current inhibitors 10,10-bis(4-pyridinylmethyl)-9(10H)-anthracenone dihydrochloride (XE-991) and linopirdine. ICA-27243 enhanced both (86)Rb(+) efflux (EC(50) = 0.2 microM) and whole-cell currents in Chinese hamster ovary cells stably expressing heteromultimeric KCNQ2/Q3 channels (EC(50) = 0.4 microM). Activation of KCNQ2/Q3 channels was associated with a hyperpolarizing shift of the voltage dependence of channel activation (V((1/2)) shift of -19 mV at 10 microM). In contrast, ICA-27243 was less effective at activating KCNQ4 and KCNQ3/Q5 and was selective over a wide range of neurotransmitter receptors and ion channels such as voltage-dependent sodium channels and GABA-gated chloride channels. ICA-27243 (1-10 microM) was found to reversibly suppress seizure-like activity in an ex vivo hippocampal slice model of epilepsy and demonstrated in vivo anticonvulsant activity (ED(50) = 8.4 mg/kg) in the mouse maximal electroshock epilepsy model. In conclusion, ICA-27243 represents the first member of a novel chemical class of selective KCNQ2/Q3 activators with anticonvulsant-like activity in experimental models of epilepsy.


Sujet(s)
Benzamides/pharmacologie , Canal potassique KCNQ2/effets des médicaments et des substances chimiques , Canal potassique KCNQ3/effets des médicaments et des substances chimiques , Pyridines/pharmacologie , Animaux , Cellules CHO , Techniques de culture cellulaire , Lignée cellulaire , Lignée cellulaire tumorale , Cricetinae , Cricetulus , Relation dose-effet des médicaments , Électrophysiologie , Hippocampe/métabolisme , Humains , Concentration inhibitrice 50 , Rein/cytologie , Mâle , Potentiels de membrane/effets des médicaments et des substances chimiques , Microélectrodes , Neuroblastome/anatomopathologie , Techniques de patch-clamp , Plasmides , ARN messager/analyse , Rats , Rat Sprague-Dawley , Sensibilité et spécificité
5.
Neuroscience ; 150(1): 82-92, 2007 Nov 30.
Article de Anglais | MEDLINE | ID: mdl-17904295

RÉSUMÉ

The mechanism by which the sedative and amnestic recreational drug gamma hydroxybutyric acid (GHB) acts is controversial. Some studies indicate that it acts at its unique receptor, while others demonstrate effects mediated through the GABAB receptor. We examined the effect of GHB on evoked GABAA receptor-mediated mono- and polysynaptic inhibitory postsynaptic currents (IPSCs) as well as on N-methyl-d-aspartate (NMDA) and AMPA-mediated excitatory postsynaptic currents (EPSCs) in layers II/III pyramidal cells of the frontal cortex of rat brain. One millimolar (mM) GHB suppressed monosynaptic IPSCs by 20%, whereas polysynaptic IPSCs were reduced by 56%. GHB (1 mM) also produced a significant suppression of NMDA-mediated EPSCs by 53% compared with 27% suppression of AMPA-mediated EPSCs. All effects of GHB on IPSCs and EPSCs were reversed by the specific GABAB antagonist CGP 62349, but not by the GHB receptor antagonist (2E)-5-hydroxy-5,7,8,9-tetrahydro-6H-benzo[a][7]annulen-6-ylidene ethanoic acid. Consistent with a presynaptic site of action, GHB reduced the frequency but not the amplitude of AMPA receptor-mediated mEPSCs and had no effect on postsynaptic currents evoked by direct application of NMDA. Finally, even though GHB appeared to be acting at presynaptic GABAB receptors, GHB and the GABAB agonist baclofen appeared to have opposite potencies for depression of NMDA- vs. AMPA-mediated EPSCs. GHB showed a preference for depressing NMDA responses while baclofen more potently suppressed AMPA responses. The suppression of NMDA more than AMPA responses by GHB at intoxicating doses may make it attractive as a recreational drug and may explain why GHB is abused and baclofen is not.


Sujet(s)
Anesthésiques intraveineux/pharmacologie , Potentiels post-synaptiques excitateurs/effets des médicaments et des substances chimiques , Potentiels post-synaptiques inhibiteurs/effets des médicaments et des substances chimiques , Néocortex/effets des médicaments et des substances chimiques , Oxybate de sodium/pharmacologie , Animaux , Animaux nouveau-nés , Benzoates/pharmacologie , Interactions médicamenteuses , Stimulation électrique/méthodes , Agents des acides aminés excitateurs/pharmacologie , Potentiels post-synaptiques excitateurs/physiologie , Agents GABA/pharmacologie , Techniques in vitro , Potentiels post-synaptiques inhibiteurs/physiologie , Mâle , Composés organiques du phosphore/pharmacologie , Rats , Rat Sprague-Dawley
6.
Neuropharmacology ; 46(1): 1-9, 2004 Jan.
Article de Anglais | MEDLINE | ID: mdl-14654092

RÉSUMÉ

Benzodiazepines are among the most widely prescribed therapeutic agents, having anxiolytic, anticonvulsant, sedative/hypnotic, and amnestic properties (Mehta and Ticku, Brain Res. Rev. 29 (1999) 196). Recent research indicates that these disparate actions are dissociable (Nature 401 (1999) 796; Science 290 (2000) 131; Kralic et al., Neuropharmacology 43 (2002) 685). Behavioral studies indicate that the amygdala plays a critical role in the anxiolytic effect of benzodiazepines (Nagy et al., Neuropharmacology 18 (1979) 573; The amygdala: anxiety and benzodiazepines. The Amygdala: a Functional Analysis. p. 195). However, the neuronal substrates of this anxiolytic effect remain unclear. Our study characterizes the physiological response to acute application of the benzodiazepine diazepam and the non-benzodiazepine sedative zolpidem using whole cell patch recording in two discrete amygdala subnuclei. We found that acute application of diazepam enhances GABA(A) receptor-mediated inhibitory postsynaptic currents (IPSCs) with equal potency in the basolateral (BL) and central (Ce) amygdala subnuclei. However, zolpidem enhanced IPSCs with similar potency only in the BL, and was effective in the Ce only at high concentrations. This finding is in agreement with histochemical data regarding the localization of GABA(A) receptor isoforms in the amygdala (J. Comp. Neurol. 359 (1995) 154; Brain Res. 964 (2003) 91) and suggests that anxiolytic effects of allosteric modulators of the GABA(A) receptor may be further dissociated from their hypnotic/sedative effects.


Sujet(s)
Amygdale (système limbique)/effets des médicaments et des substances chimiques , Bicuculline/analogues et dérivés , Diazépam/pharmacologie , Agonistes GABA/pharmacologie , Modulateurs GABA/pharmacologie , Pyridines/pharmacologie , Valine/analogues et dérivés , Animaux , Animaux nouveau-nés , Bicuculline/pharmacologie , Relation dose-effet des médicaments , Interactions médicamenteuses , Stimulation électrique , Potentiels évoqués/effets des médicaments et des substances chimiques , Potentiels évoqués/effets des radiations , Antagonistes des acides aminés excitateurs/pharmacologie , Antagonistes GABA/pharmacologie , Techniques in vitro , Mâle , Inhibition nerveuse/effets des médicaments et des substances chimiques , Techniques de patch-clamp/méthodes , Quinoxalines/pharmacologie , Rats , Rat Sprague-Dawley , Valine/pharmacologie , Zolpidem
7.
Lupus ; 11(11): 756-8, 2002.
Article de Anglais | MEDLINE | ID: mdl-12475007

RÉSUMÉ

We report the case of a 72-year-old female with sarcoidosis who developed a central retinal artery occlusion in her left eye in association with persistently high titers of IgG anti-cardiolipin antibodies. Only two previous cases of antiphospholipid antibody syndrome in association with sarcoidosis have been reported. Our patient's vision stabilized on anti-coagulant therapy along with concomitant treatment of sarcoidosis-related uveitis with methotrexate.


Sujet(s)
Syndrome des anticorps antiphospholipides/complications , Occlusion artérielle rétinienne/étiologie , Sarcoïdose/complications , Sujet âgé , Femelle , Humains , Artère centrale de la rétine
8.
FEBS Lett ; 506(3): 277-80, 2001 Oct 12.
Article de Anglais | MEDLINE | ID: mdl-11602261

RÉSUMÉ

Pho85p is a yeast cyclin-dependent protein kinase (Cdk) that can interact with 10 cyclins (Pcls) to form multiple protein kinases. The functions of most of the Pcls, including Pc16p and Pc17p, are poorly defined. We report here that Pc16p and Pc17p are involved in the metabolism of the branched storage polysaccharide glycogen under certain conditions and deletion of PCL6 and PCL7 restores glycogen accumulation to a snf1 pcl8 pcl10 triple mutant, paradoxically activating both glycogen synthase and phosphorylase. Pho85p thus affects glycogen accumulation through multiple Cdks composed of different cyclin partners.


Sujet(s)
Kinases cyclines-dépendantes/physiologie , Cyclines/physiologie , Glycogène/métabolisme , Protéines de Saccharomyces cerevisiae/physiologie , Saccharomyces cerevisiae/métabolisme , Kinases cyclines-dépendantes/génétique , Cyclines/génétique , Activation enzymatique , Glycogen phosphorylase/métabolisme , Glycogen synthase/métabolisme , Mutation , Isoformes de protéines/génétique , Isoformes de protéines/physiologie , Protéines de Saccharomyces cerevisiae/génétique
9.
Rheum Dis Clin North Am ; 27(3): 499-505, v, 2001 Aug.
Article de Anglais | MEDLINE | ID: mdl-11534256

RÉSUMÉ

The major purpose of the 1999 international consensus criteria for definite antiphospholipid syndrome (APS) is to facilitate the selection of uniform groups of patients for clinical and experimental studies. An early evaluation suggests that the criteria fulfill this purpose when tested in patients with systemic lupus erythematosus or lupus-like diseases. The criteria will likely need modification as investigators appraise and reach consensus about new information on APS. The international APS symposium has had an important role in this process and provides a mechanism for facilitating future advances in this subject.


Sujet(s)
Syndrome des anticorps antiphospholipides/classification , Lupus érythémateux disséminé/complications , Syndrome des anticorps antiphospholipides/diagnostic , Syndrome des anticorps antiphospholipides/anatomopathologie , Diagnostic différentiel , Humains , Indice de gravité de la maladie
10.
J Neurophysiol ; 86(3): 1422-9, 2001 Sep.
Article de Anglais | MEDLINE | ID: mdl-11535688

RÉSUMÉ

Although the synaptic physiology of the amygdala has been studied with single neuron recordings, the properties of the networks between the various nuclei have resisted characterization because of the limitations of field recording in a neuronally diffuse structure. We addressed this issue in the rat amygdala complex in vitro by using a photodiode array coupled with a voltage-sensitive dye. Low-intensity single pulse stimulation of the lateral amygdala nucleus produced a complex multi-phasic potential. This signal propagated to the basolateral nucleus and the amygdalostriatal transition zone but not to the central nucleus. The local potential, which depended on both synaptic responses and activation of voltage-dependent ion channels, was reduced in amplitude by the non-N-methyl-D-aspartate (non-NMDA) glutamate receptor antagonist 6,7-dinitroquinoxaline (DNQX) and reduced to a lesser extent by the NMDA glutamate receptor antagonist D-2-amino-5-phosphonovaleric acid (D-APV). We next characterized the less complex signals that propagated to more distal regions with or without the addition of the GABA receptor antagonist bicuculline (BIC). BIC alone greatly increased the signal propagation and permitted activation of previously silent areas within the amygdala. DNQX blocked signal propagation to amygdala regions outside of La, even in the presence of BIC, whereas D-APV had minimal effects on these distal signals. These data represent several novel findings: the characterization of the multi-component potential near the site of stimulation, the gating of signal propagation within the amygdala by GABAergic inhibition, the critical role of non-NMDA receptor-mediated depolarization in signal propagation, and the lack of a role for NMDA receptors in maintaining propagation.


Sujet(s)
Amygdale (système limbique)/physiologie , Récepteur de l'AMPA/physiologie , Récepteurs GABA/physiologie , Récepteurs du N-méthyl-D-aspartate/physiologie , Transmission synaptique/physiologie , Amino-2 phosphono-5 valérate/pharmacologie , Animaux , Bicuculline/pharmacologie , Agents colorants , Antagonistes des acides aminés excitateurs/pharmacologie , Antagonistes GABA/pharmacologie , Traitement d'image par ordinateur , Mâle , Techniques de culture d'organes , Quinoxalines/pharmacologie , Rats , Rat Sprague-Dawley , Transmission synaptique/effets des médicaments et des substances chimiques
11.
Lupus ; 10(7): 457-60, 2001.
Article de Anglais | MEDLINE | ID: mdl-11480841

RÉSUMÉ

An international workshop on classification criteria for antiphospholipid syndrome (APS) was held on 16 September 2000 in Tours, France, following the Ninth International APS Symposium. The workshop addressed issues that were not resolved by the previous (1998) international workshop on the classification criteria. Participants at the workshop agreed that no changes should be made to the international (Sapporo) criteria at the present time. However, to improve the criteria, future efforts should be focused on the following: (1) further evaluation of the international (Sapporo) criteria for definite APS; (2) definition of other categories of APS such as 'probable' and 'possible' APS; (3) guidelines for the clinical diagnosis as distinct from classification of APS; (4) strategies to improve the compliance of laboratories worldwide, with recommended procedures for Lupus anticoagulant (LA) and anticardiolipin (aCL) assays; (5) development of monoclonal antibody standard reagents for aCL and LA assays; and (6) refinement and subsequent evaluation of antibeta2GPI assays for use in idenfitication of APS.


Sujet(s)
Syndrome des anticorps antiphospholipides/classification , Syndrome des anticorps antiphospholipides/diagnostic , Glycoprotéines/immunologie , Humains , Inhibiteur lupique de la coagulation/analyse , Phosphatidyléthanolamine/immunologie , bêta 2-Glycoprotéine I
12.
Mol Cell Biol ; 21(17): 5742-52, 2001 Sep.
Article de Anglais | MEDLINE | ID: mdl-11486014

RÉSUMÉ

In the yeast Saccharomyces cerevisiae, glycogen is accumulated as a carbohydrate reserve when cells are deprived of nutrients. Yeast mutated in SNF1, a gene encoding a protein kinase required for glucose derepression, has diminished glycogen accumulation and concomitant inactivation of glycogen synthase. Restoration of synthesis in an snf1 strain results only in transient glycogen accumulation, implying the existence of other SNF1-dependent controls of glycogen storage. A genetic screen revealed that two genes involved in autophagy, APG1 and APG13, may be regulated by SNF1. Increased autophagic activity was observed in wild-type cells entering the stationary phase, but this induction was impaired in an snf1 strain. Mutants defective for autophagy were able to synthesize glycogen upon approaching the stationary phase, but were unable to maintain their glycogen stores, because subsequent synthesis was impaired and degradation by phosphorylase, Gph1p, was enhanced. Thus, deletion of GPH1 partially reversed the loss of glycogen accumulation in autophagy mutants. Loss of the vacuolar glucosidase, SGA1, also protected glycogen stores, but only very late in the stationary phase. Gph1p and Sga1p may therefore degrade physically distinct pools of glycogen. Pho85p is a cyclin-dependent protein kinase that antagonizes SNF1 control of glycogen synthesis. Induction of autophagy in pho85 mutants entering the stationary phase was exaggerated compared to the level in wild-type cells, but was blocked in apg1 pho85 mutants. We propose that Snf1p and Pho85p are, respectively, positive and negative regulators of autophagy, probably via Apg1 and/or Apg13. Defective glycogen storage in snf1 cells can be attributed to both defective synthesis upon entry into stationary phase and impaired maintenance of glycogen levels caused by the lack of autophagy.


Sujet(s)
Kinases cyclines-dépendantes/métabolisme , Protéines fongiques/métabolisme , Glycogène/métabolisme , Protein-Serine-Threonine Kinases/métabolisme , Protéines de Saccharomyces cerevisiae , AMP-Activated Protein Kinases , Protéines adaptatrices de la transduction du signal , Protéines associées à l'autophagie , Glucan 1,4-alpha-glucosidase/métabolisme , Isoenzymes/métabolisme , Complexes multienzymatiques/métabolisme , Mutagenèse , Phénotype , Phosphoprotéines/génétique , Phosphoprotéines/métabolisme , Phosphorylases/génétique , Phosphorylases/métabolisme , Protein-Serine-Threonine Kinases/génétique , Saccharomyces cerevisiae/génétique , Saccharomyces cerevisiae/croissance et développement , Saccharomyces cerevisiae/métabolisme
13.
Neuroscience ; 105(3): 547-52, 2001.
Article de Anglais | MEDLINE | ID: mdl-11516822

RÉSUMÉ

Alcoholism and alcohol abuse create costly social and economic problems in many nations. Recent studies indicate that alcohol exposure during adolescence may convey unique risks for subsequent neurocognitive deficits and problem drinking. Although GABA(A) receptor function is one of the principle neurochemical targets of ethanol action in the adult brain, little is known about the effects of alcohol on this system during adolescence. Adolescent (30-day-old) and adult (90-day-old) male rats were intermittently exposed to ethanol for 1 month. At various times after the end of the exposure period, synaptoneurosomes were prepared from their cerebral cortices. GABA(A) receptor-mediated 36Cl(-) influx was measured in the absence and presence of the neurosteroid 3alpha,21-dihydroxy-5alpha-pregnan-20-one (THDOC). In tissue from ethanol-exposed animals, sensitization to the potentiating effects of the neurosteroid was apparent 5 and 12 days after ethanol withdrawal. This sensitization was more apparent at the low concentrations of THDOC in animals pretreated with ethanol as adolescents. Sensitization to the potentiating effects of a neurosteroid is an enduring phenomenon, persistent long after the acute phase of ethanol withdrawal, and may be indicative of long-term changes in GABA(A) receptor function. Enhanced neurosteroid sensitization in animals pretreated as adolescents is consistent with the notion that adolescence is a period of unique sensitivity to the effects of ethanol. This uniqueness may now be extended to the chronic effects of ethanol.


Sujet(s)
Vieillissement/physiologie , Anxiolytiques/pharmacologie , Canaux chlorure/effets des médicaments et des substances chimiques , Désoxycorticostérone/analogues et dérivés , Désoxycorticostérone/pharmacologie , Interactions médicamenteuses/physiologie , Éthanol/pharmacologie , Récepteurs GABA-A/effets des médicaments et des substances chimiques , Adolescent , Troubles neurologiques dus à l'alcool/métabolisme , Troubles neurologiques dus à l'alcool/physiopathologie , Animaux , Encéphale/effets des médicaments et des substances chimiques , Encéphale/métabolisme , Encéphale/physiopathologie , Canaux chlorure/métabolisme , Chlore/pharmacocinétique , Maladie chronique , Relation dose-effet des médicaments , Calendrier d'administration des médicaments , Agonistes GABA/pharmacologie , Humains , Mâle , Muscimol/pharmacologie , Radio-isotopes/pharmacocinétique , Rats , Rat Sprague-Dawley , Récepteurs GABA-A/métabolisme , Synaptosomes/effets des médicaments et des substances chimiques , Synaptosomes/métabolisme
15.
J Autoimmun ; 15(2): 153-5, 2000 Sep.
Article de Anglais | MEDLINE | ID: mdl-10968902

RÉSUMÉ

Ethnic and geographic studies have contributed to knowledge of the clinical epidemiology of APS. In general, these studies support the associations of aPL with thrombosis and pregnancy morbidity, with some exceptions. Further investigation is needed to determine whether the exceptions represent interethnic variation in the clinical associations of aPL and thus provide clues to the causation of APS, or alternatively, whether methodologic factors are responsible.


Sujet(s)
Syndrome des anticorps antiphospholipides/ethnologie , Syndrome des anticorps antiphospholipides/épidémiologie , Syndrome des anticorps antiphospholipides/génétique , Humains
16.
J Biol Chem ; 275(36): 27753-61, 2000 Sep 08.
Article de Anglais | MEDLINE | ID: mdl-10874034

RÉSUMÉ

The major yeast glycogen synthase, Gsy2p, is inactivated by phosphorylation and activated by the allosteric ligand glucose-6-P. From studies of recombinant proteins, the control can be accommodated by a three-state model, in which unphosphorylated enzyme has intermediate activity (state II). Glucose-6-P increased V(max)/K(m) by about 2-fold (state III), whereas phosphorylation by the cyclin-dependent protein kinase Pcl10p/Pho85p decreased V(max)/K(m) by approximately 30-fold (state I). In the presence of glucose-6-P, state III is achieved regardless of phosphorylation state. The enzyme forms complexes in solution with the yeast glycogenin Glg2p, but this interaction appears not to affect control either by glucose-6-P binding or by phosphorylation. Scanning mutagenesis was applied to identify residues potentially involved in ligand binding. Of 22 mutant enzymes analyzed, seven were essentially inactive. Five mutant proteins were altered in their activation by glucose-6-P, and two were completely unaffected by the hexose phosphate. One of these, R586A/R588A/R591A (all three of the indicated Arg residues mutated to Ala), had wild-type activity and was normally inactivated by phosphorylation. A second mutant, R579A/R580A/R582A, had somewhat reduced V(max), but its activity was not greatly reduced by phosphorylation. The Arg residues in these two mutants are restricted to a highly conserved, 13-residue segment of Gsy2p that we propose to be important for glucose-6-P binding and/or the ability of the enzyme to undergo transitions between activity states.


Sujet(s)
Glucose-6-phosphate/métabolisme , Glycogen synthase/composition chimique , Glycogen synthase/métabolisme , Régulation allostérique , Séquence d'acides aminés , Substitution d'acide aminé , Animaux , Séquence consensus , Humains , Cinétique , Ligands , Foie/enzymologie , Modèles biologiques , Données de séquences moléculaires , Muscles squelettiques/enzymologie , Mutagenèse dirigée , Phosphorylation , Lapins , Protéines recombinantes/composition chimique , Protéines recombinantes/métabolisme , Alignement de séquences , Similitude de séquences d'acides aminés
18.
J Neurophysiol ; 83(2): 685-92, 2000 Feb.
Article de Anglais | MEDLINE | ID: mdl-10669484

RÉSUMÉ

Afferent stimulation of pyramidal cells in the basolateral amygdala produced mixed excitatory postsynaptic potentials (EPSPs) mediated by N-methyl-D-aspartate (NMDA) and non-NMDA glutamate receptors during whole cell current-clamp recordings. In the presence of GABA(A) receptor blockade, the mixed EPSPs recruited a large "all-or-none" depolarizing event. This recruited event was voltage dependent and had a distinct activation threshold. An analogous phenomenon elicited by exogenous glutamate in the presence of tetrodotoxin (TTX) was blocked by Cd(2+), suggesting that the event was a Ca(2+) spike. Selective glutamatergic blockade revealed that these Ca(2+) spikes were recruited readily by single afferent stimulus pulses that elicited NMDA EPSPs. In contrast, non-NMDA EPSPs induced by single stimuli failed to elicit the Ca(2+) spike even at maximal stimulus intensities although these non-NMDA EPSPs depolarized the soma more effectively than mixed EPSPs. Elongation of non-NMDA EPSPs by cyclothiazide or brief trains of stimulation were also unable to elicit the Ca(2+) spike. Blockade of K(+) channels with intracellular Cs(+) enabled single non-NMDA EPSPs to activate the Ca(2+) spike. The finding that voltage-dependent calcium channels are activated preferentially by NMDA-receptor-mediated EPSPs provides a mechanism for NMDA-receptor-dependent plasticity independent of Ca(2+) influx through the NMDA receptor.


Sujet(s)
Amygdale (système limbique)/composition chimique , Canaux calciques/physiologie , Récepteurs du N-méthyl-D-aspartate/physiologie , Synapses/physiologie , Amino-2 phosphono-5 valérate/pharmacologie , Potentiels d'action/effets des médicaments et des substances chimiques , Potentiels d'action/physiologie , Amygdale (système limbique)/physiologie , Animaux , Bicuculline/analogues et dérivés , Bicuculline/pharmacologie , Calcium/pharmacocinétique , Césium/pharmacologie , Maléate de dizocilpine/pharmacologie , Agonistes des acides aminés excitateurs/pharmacologie , Antagonistes des acides aminés excitateurs/pharmacologie , Potentiels post-synaptiques excitateurs/effets des médicaments et des substances chimiques , Potentiels post-synaptiques excitateurs/physiologie , Acide glutamique/pharmacologie , Mâle , N-Méthyl-aspartate/pharmacologie , Techniques de patch-clamp , Inhibiteurs des canaux potassiques , Quinoxalines/pharmacologie , Rats , Rat Sprague-Dawley , Tétrodotoxine/pharmacologie , AMPA/pharmacologie
19.
Brain Res Dev Brain Res ; 118(1-2): 159-67, 1999 Dec 10.
Article de Anglais | MEDLINE | ID: mdl-10611515

RÉSUMÉ

Supplementation with choline during pregnancy in rats causes a long-lasting improvement of visuospatial memory of the offspring. To determine if the behavioral effects of choline are related to physiological changes in hippocampus, the effect of perinatal choline supplementation or deficiency on long-term potentiation (LTP) was examined in hippocampal slices of 6-8 and 12-14 month old rats born to dams consuming a control, choline-supplemented, or a choline-free diet during pregnancy. Stimulating and recording electrodes were placed in stratum radiatum of area CA1 to record extracellular population excitatory postsynaptic potentials (pEPSPs). To induce LTP, a theta-like stimulus train was generated. The amplitude of the stimulus pulses was set at either 10% or 50% of the stimulus intensity which had induced the maximal pEPSP slope on the input/output curve. We found that at both ages, a significantly smaller percentage of slices from perinatally choline-deficient rats displayed LTP after 10% stimulus intensity (compared with control and choline-supplemented rats), and a significantly larger percentage of slices from choline-supplemented rats displayed LTP at 50% stimulus intensity (compared with control and choline-deficient rats). Results reveal that alterations in the availability of dietary choline during discrete periods of development lead to changes in hippocampal electrophysiology that last well into adulthood. These changes in LTP threshold may underlie the observed enhancement of visuospatial memory seen after prenatal choline supplementation and point to the importance of choline intake during pregnancy for development of brain and memory function.


Sujet(s)
Animaux nouveau-nés/physiologie , Choline/pharmacologie , Foetus/effets des médicaments et des substances chimiques , Hippocampe/physiologie , Potentialisation à long terme/physiologie , Effets différés de l'exposition prénatale à des facteurs de risque , Vieillissement/physiologie , Animaux , Stimulation électrique/méthodes , Femelle , Hippocampe/effets des médicaments et des substances chimiques , Techniques in vitro , Potentialisation à long terme/effets des médicaments et des substances chimiques , Mâle , Grossesse , Rats , Rat Sprague-Dawley
20.
Alcohol ; 19(2): 107-11, 1999 Oct.
Article de Anglais | MEDLINE | ID: mdl-10548153

RÉSUMÉ

Hippocampal long-term potentiation (LTP) is strongly associated with the acquisition of spatial memory and is attenuated by ethanol. Recent studies have shown that the inhibitory potency of ethanol against n-methyl-d-aspartate (NMDA) receptor-mediated synaptic activity is enhanced in hippocampal slices taken from juvenile rats compared to those taken from adults. In addition, ethanol has been reported to impair spatial memory acquisition at lower doses in adolescent rats compared to adults. We therefore hypothesized that the suppression of hippocampal LTP by ethanol would be more potent in hippocampal slices taken from adolescent rats compared to those taken from adults. The potency of ethanol against NMDA receptor-mediated LTP was assessed in area CA1 of hippocampal slices taken from adolescent (30 days old) and adult (90 days old) rats. In slices from adolescent rats, theta-burst stimulus trains reliably induced robust LTP in the absence of ethanol, but when the stimulus trains were presented in the presence of either 10 mM or 30 mM ethanol, LTP induction was significantly suppressed relative to controls. In contrast, there was no effect of these ethanol concentrations on the induction of LTP in hippocampal slices from adult rats. These observations indicate that ethanol suppresses LTP in the adolescent hippocampus at concentrations that do not affect than it suppresses in the adult slices, suggesting a much greater sensitivity to ethanol in adolescence.


Sujet(s)
Dépresseurs du système nerveux central/pharmacologie , Éthanol/pharmacologie , Potentiels post-synaptiques excitateurs/effets des médicaments et des substances chimiques , Hippocampe/effets des médicaments et des substances chimiques , Potentialisation à long terme/effets des médicaments et des substances chimiques , Facteurs âges , Animaux , Dépresseurs du système nerveux central/administration et posologie , Éthanol/administration et posologie , Hippocampe/physiologie , Mâle , Rats , Rat Sprague-Dawley
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