摘要:

APOLIPOPROTEIN E (apoE) and the β-amyloid peptide are both found in the senile plaques associated with Alzheimer's disease. Several studies have recently determined that apoE can prevent β-amyloid fibril (Aβf) formation in vitro. In vivo, apoE is normally associated with a lipid source. We show that both recombinant and purified plasma apoE inhibit Aβf formation in a dose-dependent manner. The three major apoE isoforms were equipotent at inhibiting Aβf formation. ApoE associated with either cholesterol-containing liposomes or very low density lipoproteins displayed less potent inhibition of Aβf formation than their unlipidated counterparts. These results indicate that the presence of associated lipids reduce the ability of apoE to inhibit the formation of Aβf in vitro.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

WE tried to identify the mechanisms directly related to syntactic processing in an fMRI experiment using strictly controlled sets of verbal stimuli. In two conditions, center-embedding and left-branching conditions, the same sets of words were used to construct stimulus sentences, while only the word order reflecting their syntactic structure was different. The subject's task was to understand the relationship among three characters mentioned in the sentences. A difference of activation in Broca's area (BA44 and 45) between the two conditions was found. This result suggests that these areas are involved in syntax-related processing. Furthermore, it was suggested that the posterior part of the frontal lobe (BA6/9) and the inferior parietal area (BA39/40) are involved in the understanding of the relationship among the three characters mentioned in each sentence.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE effect of the GTP-analogue guanylyl 5′-imidodiphosphate (Gpp[NH]p) on [3H]forskolin binding was studied in rat brain using autoradiography. In the striatum, 100 μM Gpp[NH]p produced a 40% increase in binding, whereas a decrease of about 30% was observed with low Gpp[NH]p concentrations (0.1–1 μM). In the molecular layer of the cerebellum all concentrations of Gpp[NH]p decreased [3H]forskolin binding. The decrease in binding disappeared in both striatum and the molecular layer of cerebellum in sections pretreated with 100 m μM N-ethylmaleimide (NEM) for 10 min. NEM pretreatment did not significantly affect the stimulation of [3H]forskolin binding by micromolar concentrations of Gpp[NH]p in the striatum, but reversed the decrease observed in the molecular layer of the cerebellum, to an increase. Based on these data we suggest that the effects of the GTP-analogue Gpp[NH]p on [3H]forskolin binding may involve both Gsand Gi, where a stimulation produces an increase and decrease in binding respectively. The regional effects of Gpp[NH]p may reflect differences in the responsiveness of adenylyl cyclase to Gsand Gi-mediated effects.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

MUTATIONS in the presenilin-1 (PS-1) gene account for the majority of early onset autosomal-dominant familial Alzheimer's disease (FAD) cases. We identified three missense mutations in the coding sequence of the PS-1 gene in three early onset (EO), FAD pedigrees. Alzheimer's disease was confirmed in one pedigree by autopsy. Mutation analysis of PCR products amplified from genomic DNA templates of affected individuals showed two novel mutations resulting in Ser169Leu and Pro436Gln and one known mutation resulting in Glu318Gly. The two new mutations are located within predicted transmembrane domains three (TM-3) and seven (TM-7), and are associated with a very early age of onset which is consistent with a marked loss of function of the protein. The age of onset in the pedigree with Glu318Gly mutation was similar to that reported previously in a separate pedigree with this mutation.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

CEREBRAL lateralization, the differing specializations of the right and left sides of the brain once thought to be unique of humans, is now well known to occur in both birds and mammals. Here we report that in toads the right hemisfield of vision guides predatory tongue-striking responses towards moving prey and the left hemisfield guides agnostic tongue-striking responses towards conspecifics. This indicates, for the first time, complementary cerebral specializations for visual processing in anurans, and strongly supports the hypothesis that lateralized brain functions in birds and mammals may have arisen from a common lateralized ancestor. Complementary specializations in visual processing may have originally evolved to avoid problem of response competition during control of medial organs such as the tongue in organisms with laterally placed eyes and, in organisms with wider binocular overlap, it appears to be retained for initial detection of stimuli in the extreme lateral fields.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID