Faculty Bibliography

Alzheimer's disease (AD) is associated with increased brain levels of beta-amyloid (Abeta) peptides, which readily self-aggregate into fibrils and oligomers that have particularly deleterious properties toward synapses of excitatory glutamatergic neurons. Here, we examined the neuroprotective effects of 1-methyl-1,2,3,4,-tetrahydroisoquinoline (1MeTIQ) against Abeta-induced loss of synaptic proteins in cultured primary hippocampal neurons. Exposure of mature primary hippocampal neurons to 10 muM synthetic Abeta1-40 over 72 h resulted in ~60 % reduction in the surface expression of NR1 subunit of the NMDA receptor (NMDAR), PSD-95, and synaptophysin, without causing neuronal death. Concomitant treatment with 500 muM of 1MeTIQ, a low-affinity NMDAR antagonist significantly ameliorated the loss of synaptic protein markers. The neuroprotective properties of 1MeTIQ were compared with those of MK-801, which at 0.5 muM concentration also prevented Abeta1-40-induced loss of synaptic proteins in primary neuronal cultures. Furthermore, we provide novel evidence demonstrating effectiveness of 1MeTIQ in reducing the level of reactive oxygen species (ROS) in primary neuronal culture system. As oxidative stress contributes importantly to neurodegeneration in AD, 1MeTIQ may provide a dual neuroproctective effect in AD both as a NMDARs antagonist and ROS formation inhibitor. 1MeTIQ occurs endogenously at low concentrations in the brain and its synthetic form readily penetrates the blood-brain barrier after the systemic administration. Our results highlight a possibility of the application of 1MeTIQ as a neuroprotective agent in AD-related neurodegeneration.

BACKGROUND: Bapineuzumab, a humanized anti-amyloid-beta monoclonal antibody, is in clinical development for the treatment of Alzheimer's disease. METHODS: We conducted two double-blind, randomized, placebo-controlled, phase 3 trials involving patients with mild-to-moderate Alzheimer's disease--one involving 1121 carriers of the apolipoprotein E (APOE) epsilon4 allele and the other involving 1331 noncarriers. Bapineuzumab or placebo, with doses varying by study, was administered by intravenous infusion every 13 weeks for 78 weeks. The primary outcome measures were scores on the 11-item cognitive subscale of the Alzheimer's Disease Assessment Scale (ADAS-cog11, with scores ranging from 0 to 70 and higher scores indicating greater impairment) and the Disability Assessment for Dementia (DAD, with scores ranging from 0 to 100 and higher scores indicating less impairment). A total of 1090 carriers and 1114 noncarriers were included in the efficacy analysis. Secondary outcome measures included findings on positron-emission tomographic amyloid imaging with the use of Pittsburgh compound B (PIB-PET) and cerebrospinal fluid phosphorylated tau (phospho-tau) concentrations. RESULTS: There were no significant between-group differences in the primary outcomes. At week 78, the between-group differences in the change from baseline in the ADAS-cog11 and DAD scores (bapineuzumab group minus placebo group) were -0.2 (P=0.80) and -1.2 (P=0.34), respectively, in the carrier study; the corresponding differences in the noncarrier study were -0.3 (P=0.64) and 2.8 (P=0.07) with the 0.5-mg-per-kilogram dose of bapineuzumab and 0.4 (P=0.62) and 0.9 (P=0.55) with the 1.0-mg-per-kilogram dose. The major safety finding was amyloid-related imaging abnormalities with edema among patients receiving bapineuzumab, which increased with bapineuzumab dose and APOE epsilon4 allele number and which led to discontinuation of the 2.0-mg-per-kilogram dose. Between-group differences were observed with respect to PIB-PET and cerebrospinal fluid phospho-tau concentrations in APOE epsilon4 allele carriers but not in noncarriers. CONCLUSIONS: Bapineuzumab did not improve clinical outcomes in patients with Alzheimer's disease, despite treatment differences in biomarkers observed in APOE epsilon4 carriers. (Funded by Janssen Alzheimer Immunotherapy and Pfizer; Bapineuzumab 301 and 302 ClinicalTrials.gov numbers, NCT00575055 and NCT00574132, and EudraCT number, 2009-012748-17.).

Background: Disturbance of beta-amyloid (Abeta) homeostasis and its accumulation in the brain underlie early Alzheimer's disease (AD) pathogenesis. Apolipoprotein (apo) E is a lipid carrier protein, which directly interacts with Abeta promoting its oligomerization, deposition in parenchymal plaques and in the brain vasculature, and also influences the rate of Abeta brain clearance. APOE alleles are well-recognized genetic risk factors for sporadic AD and correlate with severity of beta-amyloidosis. APOE4 increases AD risk, while APOE2 shows a relative protective effect. Here, we investigated effects of the treatment with a pharmacological inhibitor of the apoE/Abeta binding on AD pathology in APP SW/PS1 dE9/apoE2-TR (TR=targeted replacement) and APP SW/PS1 dE9/apoE4-TR mice. Methods: APP SW/ PS1 dE9/apoE-TR mice were generated by crossing APP SW/PS1 dE9 transgenic mice to human apoE2-TR and apoE4-TR mice. Abeta12-28P-a synthetic peptide antagonist of the apoE/Abeta binding, which was modified for in vivo administration, or vehicle were intraperitoneally administered to the mice between the age of six and 10 months. Before conclusion of the experiment animals' memory was tested using object recognition (OR) and radial arm maze (RAM) tests. Brain Abeta load was analyzed by biochemical and morphometric methods. Results: There was no significant behavioral deficit in vehicle treated APP SW/PS1 dE9/apoE2-TR mice as compared to age and sex matched apoE2-TR mice. Abeta12-28P treatment of APP SW/PS1 dE9/ apoE2-TR animals also had no significant effect on their OR and RAM performance. In contrast, vehicle treated APP SW/PS1 dE9/apoE4-TR mice showed impaired OR behavior and on RAM test performed significantly worse than apoE4-TR mice. Abeta12-28P treatment of APP SW/PS1 dE9/ apoE4-TR mice normalized OR behavior and improved RAM performance to the level of apoE4-TR mice. Levels of soluble and insoluble Abeta x-40 and Abeta x-42 measured by ELISA in the whole brain extract and the burden of Thioflavin-S po!

Accumulation of beta-amyloid (Abeta) in the brain is a key event in Alzheimer disease pathogenesis. Apolipoprotein (Apo) E is a lipid carrier protein secreted by astrocytes, which shows inherent affinity for Abeta and has been implicated in the receptor-mediated Abeta uptake by neurons. To characterize ApoE involvement in the intraneuronal Abeta accumulation and to investigate whether blocking the ApoE/Abeta interaction could reduce intraneuronal Abeta buildup, we used a noncontact neuronal-astrocytic co-culture system, where synthetic Abeta peptides were added into the media without or with cotreatment with Abeta12-28P, which is a nontoxic peptide antagonist of ApoE/Abeta binding. Compared with neurons cultured alone, intraneuronal Abeta content was significantly increased in neurons co-cultured with wild-type but not with ApoE knockout (KO) astrocytes. Neurons co-cultured with astrocytes also showed impaired intraneuronal degradation of Abeta, increased level of intraneuronal Abeta oligomers, and marked down-regulation of several synaptic proteins. Abeta12-28P treatment significantly reduced intraneuronal Abeta accumulation, including Abeta oligomer level, and inhibited loss of synaptic proteins. Furthermore, we showed significantly reduced intraneuronal Abeta accumulation in APPSW/PS1dE9/ApoE KO mice compared with APPSW/PS1dE9/ApoE targeted replacement mice that expressed various human ApoE isoforms. Data from our co-culture and in vivo experiments indicate an essential role of ApoE in the mechanism of intraneuronal Abeta accumulation and provide evidence that ApoE/Abeta binding antagonists can effectively prevent this process.

Prionoses are a group of neurodegenerative diseases characterized by misfolding of cellular prion protein (PrP(C)) and accumulation of its diseases specific conformer PrP(Sc) in the brain and neuropathologically, they can be associated with presence or absence of PrP amyloid deposits. Functional molecular chaperones (MCs) that constitute the unfolded protein response include heat shock proteins and glucose-regulated protein families. They protect intracellular milieu against various stress conditions including accumulation of misfolded proteins and oxidative stress, typical of neurodegenerative diseases. Little is known about the role of MCs in pathogenesis of prionoses in mammalian prion model systems. In this study we characterized MCs response pattern in mice infected with various mouse adapted scrapie strains. Rather than uniform upregulation of MCs, we encountered two distinctly different patterns of MCs response distinguishing ME7 and 87V strains from 22L and 139A strains. ME7 and 87V strains are known for the induction of amyloid deposition in infected animals, while in mice infected with 22L and 139A strains amyloid deposits are absent. MCs response pattern similar to that associated with amyloidogenic ME7 and 87V strains was also observed in APPPS1-21 Alzheimer's transgenic mice, which represent an aggressive model of cerebral amyloidosis caused by beta-amyloid deposition. Our results highlight the probability that different mechanisms of MCs regulation exist driven by amyloidogenic and non-amyloidogenic nature of prion strains.

The Note reports on experimental studies of ripple born fast electrons within the TORE-SUPRA facility, which were performed by means of a modified measuring head equipped with diamond detectors designed especially for recording the electron-induced Cherenkov radiation. There are presented signals produced by fast electrons in the TORE-SUPRA machine, which were recorded during two experimental campaigns performed in 2010. Shapes of these electron-induced signals are considerably different from those observed during the first measurements carried out by the prototype Cherenkov probe in 2008. An explanation of the observed differences is given.

Transgenic (Tg) mice overexpressing human amyloid precursor protein (APP) mutants reproduce features of early Alzheimer's disease (AD) including memory deficit, presence of beta-amyloid (Abeta) oligomers, and age-associated formation of amyloid deposits. In this study we used hippocampal microdialysis to characterize the signaling of N-methyl-d-aspartic acid receptors (NMDA-Rs) in awake and behaving AD Tg mice. The NMDA-R signaling is central to hippocampal synaptic plasticity underlying memory formation and several lines of evidence implicate the role of Abeta oligomers in effecting NMDA-R dysfunction. CA1 NMDA-Rs were stimulated by NMDA infused through reverse microdialysis while changes in the cyclic guanosine monophosphate (cGMP) concentration in the brain interstitial fluid (ISF) were used to determine NMDA-Rs responsiveness. While 4 months old wild type C57BL/6 mice mounted robust cGMP response to the NMDA challenge, the same stimulus failed to significantly change the cGMP level in 4 and 15months old APP(SW) and 4 months old APP(SW)/PS1(L166P) Tg mice, which were all on C57BL/6 background. Lack of response to NMDA in AD Tg mice occurred in the absence of changes in expression levels of several synaptic proteins including synaptophysin, NR1 NMDA-R subunit and postsynaptic density protein 95, which indicates lack of profound synaptic degeneration. Abeta oligomers were detected in all three AD Tg mice groups and their concentration in the hippocampus ranged from 40.5+/-3.6ng/g in 4 months old APP(SW) mice to 60.8+/-15.9ng/g in 4 months old APP(SW)/PS1(L166P) mice. Four months old APP(SW) mice had no Abeta amyloid plaques, while the other two AD Tg mice groups showed evidence of incipient Abeta amyloid plaque formation. Our studies describes a novel approach useful to study the function of NMDA-Rs in awake and behaving AD Tg mice and demonstrate impairment of NMDA-R response in the presence of endogenously formed Abeta oligomers but predating onset of Abeta amyloidosis.

A diagnostic technique based on the Cherenkov effect is proposed for detection and characterization of fast (super-thermal and runaway) electrons in fusion devices. The detectors of Cherenkov radiation have been specially designed for measurements in the ISTTOK tokamak. Properties of several materials have been studied to determine the most appropriate one to be used as a radiator of Cherenkov emission in the detector. This technique has enabled the detection of energetic electrons (70 keV and higher) and the determination of their spatial and temporal variations in the ISTTOK discharges. Measurement of hard x-ray emission has also been carried out in experiments for validation of the measuring capabilities of the Cherenkov-type detector and a high correlation was found between the data of both diagnostics. A reasonable agreement was found between experimental data and the results of numerical modeling of the runaway electron generation in ISTTOK.