摘要:

TO evaluate the role of nitric oxide synthase (nNOS) in the pathogenesis of diabetic neuropathy, we investigated nociception and nNOS expression in dorsal root ganglion (DRG) of rats with streptozocin-induced diabetes. Paw withdrawal threshold to noxious mechanical stimuli was decreased in both L-NAME-treated and diabetic rats. The number of NADPH-diaphorase positive neurons was significantly decreased in untreated diabetic compared with control rats. Decreased expression of nNOS protein was confirmed by immunoblotting. Insulin treatment completely prevented decreases in withdrawal threshold and nNOS expression. Cyclic GMP content paralleled nNOS expression in experimental animals. These results suggest that decreased nNOS-cGMP system in DRG may play a role in the pathogenesis of diabetic sensory neuropathy.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

RODENTS with striatal C6 glioma were given carboplatin (65 mg kg−1in a 10 mg ml−1solution, i.v.) after pretreatment with the NO modulating agents 3-morpholinosydnonimine (SIN-1), NG-nitro-L-arginine methyl ester (L-NAME), bradykinin or dexamethasone, to determine whether platinum disposition in the glioma and normal brain was altered. There was no significant change in mean glioma platinum disposition after 3 days of dexamethasone (32 ± 9.7 μg/g). Treatment with SIN-1 (45.1 ± 14.2 μg/g), L-NAME (42.9 ± 4.9 μg/g) and bradykinin (45.7 ± 11.3 μg/g) all resulted in increased tumour platinum concentration compared with controls (29 ± 5.5 μg/g) but these results were not statistically significant. Dexamethasone significantly (p< 0.05) reduced the platinum concentration in normal brain but the other agents had no effect. Although glioma platinum concentration could be increased by some agents that alter tissue NO levels, the patterns of response were unpredictable and the magnitude (∼50%) of the increased platinum disposition is unlikely to be biologically significant.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

WE applied the methodology of evoked potentials (EP) to reveal the functional level of abnormality in a patient with circumscribed complete anaesthesia due to conversion disorder. EP components related to sensory and perceptual processing of both innocuous electrical and noxious laser stimuli were normal. However, a P300 component indicating cognitive processing failed to appear when using a modified oddball task with rare stimuli applied to the anaesthetic right hand. P300 was present with this paradigm stimulating the healthy left hand, as well as in a ‘malingerer’ – a healthy subject who was instructed to feign the same deficit. These results suggest cognitive deficits underlying sensory loss as conversion symptom which can be differentiated from malingering by use of P300.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

PHYSIOLOGICAL properties of mouse mossy cells were analyzed in slice preparations and compared with those of mouse CA3 pyramidal cells. They had larger input resistances, less spike-frequency adaptation, more anomalous rectification, larger amplitude spontaneous EPSP and higher frequency of spontaneous EPSP than CA3 pyramidal cells. In these respects, they resembled rat mossy cells. However, in contrast to rat mossy cells, mouse mossy cells showed pronounced burst after-hyperpolarization, comparable to that of CA3 pyramidal cells. This study revealed that mouse mossy cells are distinct from CA3 pyramidal cells in their physiological properties and further suggested that they might be less vulnerable to excitotoxic damage than rat mossy cells, as the burst after-hyperpolarization is supposed to be important in maintaining a neuron in a relatively nonexcited state.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THIS study extends the pharmacological characterization of the genotype-dependent difference in analgesic responsiveness to neuronal nicotinic agonists between CD-1 and CF-1 strains of mice. Acute analgesic potency of cytisine measured by the tail-flick assay differed by > 3200-fold between CD-1 and CF-1 outbred strains of mice. Analgesic non-responsiveness of the CF-1 strain was pharmacologically selective. Morphine produced a dose-dependent analgesic response of similar magnitude in both strains. Other pharmacological actions of cytisine, including inhibition of locomotor activity, induction of seizures and lethality, did not differ between these strains. Hyporesponsiveness to the analgesic action of both nicotine and cytisine was observed in two different CF-1 sublines. Biodistribution of [3H]cytisine in blood did not differ between the CF-1 and CD-1 strains. These pharmacological characteristics indicate that the CD-1–CF-1 strain pair provides a useful pharmacogenetic tool for investigating the mechanistic bases of analgesia induced by nicotinic cholinergic agonists.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

FUNCTIONAL magnetic resonance imaging (fMRI) is capable of detecting focal brain activation induced by electrical stimulation of single fingers in human subjects. In eight subjects somatotopic arrangement of the second and fifth finger was found in Brodmann area 3b of the primary somatosensory cortex. In four subjects the representation area of the second finger was located lateral and inferior to the fifth finger; in one subject the somatotopy was reversed. In three subjects representation areas of the two fingers in Brodmann area 3b were found overlapping. Additional activated areas were found on the crown of ipsilateral and contralateral post-central gyrus (Brodmann areas 1 and 2) and posterior parietal cortex.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

CORTICAL reorganization occurs within the primary somatosensory and the primary motor cortex after amputation of the arm or forearm. Here we report on a patient showing cortical reorganization after amputation of his right index finger. Our findings indicate that the neural networks within the area of the amputated finger in the somatosensory cortex (SI) were invaded by neighbouring structures, i.e. of neural cell assemblies that subserve the thumb and middle finger of his right hand.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE majority of early-onset familial Alzheimer's disease (FAD) is associated with mutations in the presenilin-1 (PS1) gene. We describe a novel Polish PS1 mutation of Pro117Leu, associated with the earliest average age of onset and death so far reported in a PS-linked, FAD kindred. Human kidney 293 and mouse neuroblastoma N2a cells were stably transfected with wild-type and PS1 P117L. There was a significant increase in the amyloid β42/40 ratio in the N2a P117L PS1 transfected cells compared with N2a transfected with wild-type PS1. What role PS has in the pathogenesis of AD remains to be determined, however, the severity of the clinical picture associated with this PS1 mutation stresses the importance of presenilin.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE levels and cellular localization of the mRNA encoding the inwardly rectifying potassium ion channel Kir4.1 were investigated in the embryonic rat brain by Northern blots andin situhybridization. This transcript was absent at embryonic day 13 (E13), whereas it was clearly present in E14–15 preparations, principally in the neuroepithelium of the cerebral cortex, thalamus, and hypothalamus. At later embryonic stages (E17–20), Kir4.1 mRNA levels increased and expanded to the mantle zone, such as the cortical plate, hippocampus, thalamus, and hypothalamus. The early appearance of Kir4.1 mRNA in various brain regions suggests an involvement of the channel in cell proliferation, migration and differentiation in the rat CNS.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

RETINAL γ-aminobutyric acid type C (GABAC) receptors are believed to consist of ρ subunits. The pharmacological properties of GABACreceptors appear to vary among different species. Since the mouse is an important model for gene targeting and behavioral studies, this study was aimed at cloning ρ subunits in the mouse. Here we report the isolation of two full length cDNAs corresponding to mouse ρ1 and ρ2 subunits. In contrast to the rat, both subunits in mouse are able to form homomeric receptors, but only ρ2 receptors are insensitive to picrotoxinin. Mouse ρ1 and ρ2 also co-assemble to form heteromeric receptors. These findings form the basis for further study on GABACreceptors using the mouse model.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID