摘要:

THE aim of this study was to examine the cortex during the logical processing of auditory information using a whole-cortex type dc-SQUlD gradiometer. The task modified the normal auditory oddball paradigm to require the processing of simple logic before counting a rare stimulus mentally. Although the latency of P300m did not change, a dipolar magnetic field pattern was observed over the left cerebral hemisphere at ∼280 ms poststimulus before forming the field pattern of P300m. The equivalent current dipole source was estimated to be medial to the N100m source. It was suggested that the additional load of logic processing may activate Heschl's gyri in the left hemisphere.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

IN this study, we have identified novel splice variants of the Na+channel α subunit mRNA from cultured rat astrocytes and neuroblastoma cells. These splice variants are characterized by premature truncation or deletion of a segment in the third domain of the Na+channel α subunit. The expression of three splice variants was up-regulated by exposure to 1 mM dibutyryl cAMP in spinal cord astrocytes but not in cerebral astrocytes and in B50 and B104 neuroblastoma cells. The calcium ionophore 1 μM A23187, did not influence the expression of splice variants in either astrocytes or neuroblastoma cells. These findings suggest that spinal cord astrocytes may maintain a unique regulatory pathway that participates in the control of Na+channel mRNA expression.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

RAT and gerbil hippocampus exposed to a sublethal period of ischemia becomes resistant to a subsequent period of lethal ischemia induced several days later, a phenomenon referred to as ischemic preconditioning. Here we describe ischemic preconditioning inducedin vitroin cultured hippocampal neurons. Mixed neuroglial hippocampal cell cultures of 14–17 DIV were exposed to a combined glucose and oxygen deprivation (GOD). Cultures subjected to 90 min, but not 60 min, of GOD showed extensive degeneration after a 1 day recovery period. An episode of 60 min of preconditioning GOD followed 1 and 2 days later by 90 min of GOD resulted in 40–60% protection. The data demonstrate that ischemic preconditionng can be mimicked in anin vitrohippocampal cell culture system.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

IBOGAINE, an alkaloid found in the root bark of the African shrubTabernanthe iboga, has been claimed to interrupt opioid dependence in humans; in animals, it has been shown to inhibit morphine self-administration and to attenuate signs of morphine withdrawal. However, ibogaine has some neurotoxicity, and because of this, efficacious and safer congeners of ibogaine have been sought. 18-Methoxycoronaridine (18-MC), a novel iboga alkaloid congener, has been shown, in animals, to mimic the effects of ibogaine on morphine self-administration without producing any ibogaine-like neurotoxiticity. In the present study, 18-MC was shown to attenuate five of seven signs of morphine withdrawal in rats. The data suggest that 18-MC will ameliorate symptoms of opioid dependence in humans.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

QUINOXALINEDIONES such as NBQX are neuroprotective in most models of cerebral ischemia but their poor solubility results in nephrotoxicity limiting their clinical utility. We have investigated the neuroprotective effects of a water soluble AMPA receptor antagonist, YM872, using twoin vitromodels. The viability of cortical cultures exposed to 400 μM AMPA for 15 min (16.4 ± 2.6%;n= 10) was significantly (p< 0.05) increased (84.7 ± 4.6%;n= 6) with YM872 (10 μM) in a concentration-dependent manner. Evoked post-synaptic response amplitudes in oxygen-glucose deprived hippocampal slices treated with 10 μM YM872 (3.5 ± 0.3 mV;n= 27) were significantly different from untreated deprived slices (0.3 ± 0.1 mV;n= 31,p< 0.05) and the CA1 neurons appeared viable using a confocal live/dead fluorescence assay with confocal microscopy. The neuroprotection seen with YM872in vitrowarrants further investigationin vivo.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

α2ADRENERGIC receptors are thought to play a crucial role in the etiology or treatment of mood disorders. Polymorphism(s) in the promoter region of the α2receptor may affect the gene expression and be associated with mood disorders. We studied the previously reported polymorphisms of the α2Areceptor gene at position −1291 in 114 healthy controls and 103 mood disorder patients. There was statistically no difference between controls and patients in either the genotype or the allele frequency. There was statistically no difference between the genotype and the clinical characteristics. Our results suggest there is no association between this polymorphism in the promoter region of the α2Areceptor gene and mood disorders.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

TWO novel transcripts of the human excitatory amino acid transporter EAAT2 (GLT-1) were cloned using PCR cloning techniques. Comparative sequence analysis of the 5′-untranslated region (UTR) of five EAAT2 transcripts led to the definition of five putative 5′-untranslated exons that are combined in a variable manner. Alternative splicing is a likely mechanism for the 5′ complexity of the EAAT2 cDNA. The potential functional meaning of this finding such as differential expression of the EAAT2 transcripts in the central nervous system remains to be demonstrated.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

WE provide evidence for anisotropic diffusion in rat corpus callosum and hippocampus. The preferential diffusion pathway in corpus callosum is along the myelinated axon fibres; in the hippocampus diffusion is easier along the transversal axis (x) than along the sagittal (y) or vertical (z) axes. In all areas studied, i.e. in the cortex, corpus callosum and hippocampus, the mean ECS volume fraction α (α = ECS volume/total tissue volume) ranged between 0.20 and 0.22 and mean non-specific uptake k′ was between 4.0 and 5.9 × 10−3s−1. Diffusional anisotropy in the hippocampus may be of importance for extrasynaptic transmission and in the ‘cross-talk’ between synapses.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

SEVERAL studies have shown that depressed patients have significantly lower catechol-o-methyltransferase (COMT) activity than healthy controls. Two COMT genes coding for low activity, COMTL, and high activity, COMTHhave been identified. We undertook an association study on 75 depressive disorder patients, 40 bipolar disorder patients and 135 healthy controls. All the subjects were Japanese. Patients with depressive disorders exhibited a significantly higher rate of genotypes with the COMTLallele than healthy controls (p= 0.012), which was not the case in patients with bipolar disorders. The presence of the COMTLallele was significantly associated with depressive disorders (odds ratio 2.19, 95% CI 1.19–4.03). Our results suggest the COMTLallele contributed to the etiologies of depressive disorders.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE distribution of Ca-ATPase in frog crista ampullaris was mapped ultracytochemically by using a one-step lead citrate reaction. Electron-dense precipitates, as an expression of Ca-ATPase activity, were observed on the surface of stereocilia and on the apical membrane surrounding the cuticular plate of hair cells. Sensory cells of the isthmus region showed more reactivity than those of the peripheral regions of the crista. No reaction products were detectable on the basolateral membranes and in cytoplasmatic organelles. Supporting cells of the crista showed a quite variable Ca-ATPase reaction on microvilli and on basolateral membranes. The presence of an evident reactivity on the stereocilia is consistent with the existence of an apical calcium microdomain involved in the mechano-transduction process and supports the current view that calcium ions enter the stereocilia during natural stimulation. On the other hand, the lack of an observable reactivity on the basolateral membrane of hair cells suggests that in semicircular canals other mechanisms of active transport of calcium ions across the plasma membrane, such as Na—Ca exchange, may be involved in homeostasis of the ion.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID