- Email: [email protected]
P2-143 Neuropeotective effect of cerebrolysin on organotypic hippocampal brain slices in vitro
Poster Session P2: Animal and Cellular ModeIs - Ex Vivo Models well as novel compounds. Promising candidates can be further validated in animal models of neuroinflammation. Other established screening models include proteasome dysfunction, excitotoxic injury and oxidative stress. Conclusions: Maintaining functional tissue interactions we can target complex pathogenic mechanisms such as neurotoxic events due to inflammatory reactions. Combined with an automated platform that handles organotypic cultures (TelomicsTM)an effective screening tool with accelerated throughput is now available. Models more closely recapitulating the pathogenesis of Alzheimer's disease including tau pathology triggered by amyloid toxicity are under way. This work was supported by the German government (BMBF) program 'Wachstumskerne' (Pharma MD 03WKD02D).
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NEURONAL ASSAY BASED ON DEVELOPMENTALLY INDUCIBLE EXPRESSION OF ALZHEIMER'S TAU, DESIGNED FOR SCREENING OF AD THERAPEUTICS
Peter Fifipcik . I , Miroslava Pevalova 2 , Oskar Smrzka 1, Michal Novak 2'1 .
1Axon-Neuroscience GmbH, Vienna, Austria; 21nstitute of Neuroimmunology, Bratislava, Slovakia. Contact e-mail: fiIipcik@ axon-neuroscience.at Background. Our transgenic rat model of AD showed that, expression of Alzheimer's truncated tan (AT) is causing formation of neurofibrillary degeneration similar to that observed in human AD diseased brain. Targeting of events leading to neurofibrillary pathology represents a valuable approach to treatment of Alzheimer's disease. Objective. Developing a bioassay, that is based on transgenic neurons expressing diseased forms of the tau protein. This allows screening for compounds that eliminate and prevent the deleterious effect of Alzheimer's tan. Methods, Neurons from different brain regions (cortex, hippocampus, brain stem) of transgenic and nontransgenic embryos were isolated and grown in serum free Neurobasal medium. Pure neuronal cultures and neuron-gila co-cultures were produced in parallel. Viability and cell death were determined. Western blot analysis and immunofluorescence microscopy, was performed using a panel of mAb's (DC25, Tau-1, AT-8, PHF1, MAP1, CytC GFAP). Further changes in cell morphological and organell distribution were analysed using eonfocal microscopy and videomieroscopy. Results. Transgenic primary neurons were characterized as follows: 1. Expression of AT is inducible, which permits to determine target specificity of tested compounds under controlled conditions. 2. Neurons derived from transgenic embryos exhibit altered accumulation of phosphorylated tau protein and impaired distribution of organelles. 3. Cortical neurons from transgenic rats are significantly more vulnerable to oxidative damage induced extra or intracellularly when compared to neurons of nontransgenic controls. In the assay system the viability of transgenic neurons was decreased (up to 74%) when compared to wild type neurons. Conclusion. This primary cell assay system has been established and applied for screening and validating compounds which are able to alleviate the neurodegenerative effect of Alzheimer's tau. The assay can also be extended for determination of neurotrophic effects or oxidative stress in combination with Alzheimer's tau expression.
•
TISSUE SLICE CULTURES FROM HUMAN BRAIN AUTOPSIES AND BIOPSIES: ALZHE1MER'S DISEASE AND OTHER NEUROLOGICAL DISORDERS
Ronald W. Verwer* I, Rawien Balesar 1, Lei Wu 2,1, Elisabeth F. Boiten 1, Arja A. Sluiter 1, Clemens M. Dirven 3, David E Noske 3, Robert E. Baker I , Rivka Ravid 4, Jiang-ning Zhou 2, Dick E Swaab I . 1Netherlands Institute
for Brain Research, Amsterdam, Netherlands; 2Department of Neurobiology, University of Science and Technology of China, Hefei, Anhui, China; 3Department of Neurosurgery, VU University Medical Center, Amsterdam, Netherlands; 4Netherlands Brain Bank, Amsterdam, Netherlands. Contact e-mail: [email protected] Background: We have previously shown that neurons in cultured postmortem human brain slices respond to neurotrophic factors and can express
$265
transgenes after several weeks in vitro. Viable neurons were observed in the presence of massive Alzheimer pathology (Verwer etal., FASEB J. 16: 5460, 2002). Objective(s): First, extend the characterization of the functional activity of neurons in the postmortem human brain cultures with electrophysiological recordings. Second, study the properties of endogenous/exogenous neural precursor cells (NPC) in cultures of degenerating human CNS tissue. Methods: Brain tissue slices of hippocampus, parahippocampal gyrus and motor cortex, obtained at rapid autopsies of control subjects and Alzheimer patients or obtained after surgical resection for treatment of intractable epilepsy, were cultured in chemically defined serum-free medium. Electrical recordings were performed using single electrodes and multi-electrode arrays. Neurospheres from rat embryos and adult human tissue were isolated according to existing protocols in the literature. Neurospheres (rat or human) or human brain slices containing endogenous neural precursor cells were co-cultured with slices from AD patients. Live/dead staining was used to assess the general viability of the cells in the preparations. Routine immunostaining with markers for neurons, glial cells and Alzheimer pathology was carried out to evaluate the morphological features of the tissues. Markers for early developmental stages were used to verify the nature of precursor cell preparations and the presence/absence of endogenous precursor cells in tissue slices. Results: Neurons in hippocampal slice cultures exhibited sparse electrical activity (both membrane activity and spikes) for up to 3 weeks. Probably due to selective ,mlnerability of the CA areas to ischemic conditions, electro-physiological signals were predominantly observed in the hilus area. In cortex slices from some patients endogenous NPC's were present in cortical layer I and in white matter. Occasionally, these cells were omnipresent. Co-cultures of neurospheres or NPC containing slices with host-slices from AD patients showed migration of NPC's along blood vessels into the host tissue. Conclusions: Cultures of human adult brain tissue slices obtained at rapid autopsy or at operations have a great potential for both fundamental research and the development of therapeutic and diagnostic strategies.
•
NEUROPROTECTIVE EFFECT OF CEREBROLYSIN ON ORGANOTYPIC HIPPOCAMPAL BRAIN SLICES IN VITRO
Birgit Hutter-Paier* 1, Catherine Riley t, Edith Doppler 2, Herbert Mrssler 3, Manfred Windisch 1 1jSW_Research ' Graz, Austria; 2EBEWE Pharma Nfg.
KG, Unterach, Austria; 3EBEWE Pharma GmbH Nfg. KG, Unterach, Austria. Contact e-mail: [email protected] For many years Cerebrolysin (Cere, EBEWE-Pharma Austria) has been reported to have neurotrophic and neuroprotective potential as comparable to naturally occurring growth factors like NGF or BDNF. Some of the in vitro effects of this drag are well descaibed and discussed in context to neurodegenerative disorders like Alzheimer disease and also to acute neurological disease. In the present study an organotypic brain slice protocol was to develop and used to determine the neuroprotective effects of the peptidergic drug Cerebrolysin in a glutamate lesion paradigm. Concomitant excitotoxic over-stimulation due to excess release of the excitatory neurotransmitter glutamate is one key event in ischemia. It increases intracellular calcium levels, over-activates different protein kinases and triggers enzyme reactions which finally result in excessive production of oxygen free radicals, damage of cell membranes and ultimately neuronal death. All of these measures have also been mentioned in relation to more chronic neurodegenerative diseases like Alzheimer disease. The study focused on the effects of Cere on both necrotic and apoptotic cell death after glutamate lesion. The effects of Cere (401~l/ml medium) on glutamate lesioned hippocampal slices were evaluated qualitatively and quantitatively at multiple time points before, during and after the lesion. Slices were viewed microscopically and photographed. Fluorescent readings were taken at 485 nm for Yoprol and at 520 nm for PI. Cere was added before and after the lesion as well as after the lesion alone and remained with the brain slices for distinct time periods. Our results show that the most pronounced drug effects were seen on slices that were treated with Cere both prior to and after glutamate lesioning, but that post treatment immediately after the lesion was also able to counteract neurodegeneration due to the addition of
$266
Poster Session P2: Diagnosis and Disease Progression - Neuroimaging
glutamate. In both cases Cere appears to inhibit apoptosis to a greater extent than necrosis. These positive neuroprotective effects could be relevant for the treatment of acute, as well as, chronic neurodegenerative diseases.
Poster Session P2: D i a g n o s i s and Disease Progression Neuroimaging ~ 4 ]
LEARNING AND MEMORY IN INCIPIENT AD: A FDG PET AND FMRI STUDY
Peter Schoenknecht* 1, Aoife Hunt I , Marcus Hentze 2, Freddy Giesel 3, Essig Marco 3, Pantel Johannes 4, Haberkorn Uwe 5, Johannes Schroeder 1.
1Ruprecht Karls University Heidelberg, Heidelberg, Germany; 2Ruprecht Karls University Heidelberg, Department Nuclear Medicine, Germany; 3German Cancer Research Center, Heidelberg, Germany; 4Goethe University Frankfurt a. M., Heidelberg, Germany; 5Ruprecht Karls University Heidelberg, Department Nuclear Medicine, Germany. Contact e-mail: [email protected] Background: Recent studies have demonstrated that older individuals with subclinical cognitive impairments have a higher risk for developing dementia. In several follow-up studies, patients with "mild cognitive impairment (MCI)" were found to develop Alzheimer's disease (AD) in their later life. In order to characterise subjects at risk in the early stages of the disease FDG-PET has to be investigated in subjects with MCI compared to cognitively unimpaired controls. Following the hypothesis of impaired encoding processes in subjects at risk explicit memory functions warrant further investigation. Methods: 60 subjects admitted to the Section for Geriatric Psychiatry underwent thorough clinical and neuropsychological investigation und were investigated by FDG-PET or MRI. In the functional MRI paradigm applied in a subgroup of MCI subjects brain activation during an episodic memory task (words) was studied. Results: 40 subjects were diagnosed as AD and 20 were characterised as MCI. Comparison of patients with AD and eognitively unimpaired controls revealed a significantly reduced FDG uptake in the rigth and left temporoparietal association cortex in AD patients (p < 0.05). MCI patients showed in comparison to cognitively unimpaired controls a significantly reduced FDG uptake in the temporal and parietal association cortex (p < 0.05), too. In MCI patients who underwent a fMRI word encoding task, temporal, frontal, and parietal cortex activation during word encoding was found. Conclusions: Results of this study indicate that AD can be characterised by significantly reduced FDG uptake in the temporoparietal association cortex. Since patients with MCI show a similar pattern of reduced FDG uptake in the temporal and parietal association cortex this condition might represent an early stage of the disease. Nevertheless, the temporal, frontal, and parietal cortex activation during word encoding provides insight in the explicit memory function in patients with MCI which has to be investigated further.
~-~-]
NOVEL 18F-LABELED PET TRACER FOR DETECTING AMYLOID PLAQUES AND NEUROFIBRILLARY TANGLES IN THE BRAIN
Nobuyu!d Okamura* 1,2, Takahiro Suemoto 2, Hiroshi Shimadzu 2, Masako Suzuki 2, Tsuyoshi Shiomitsu 2, Hiroyasu Akatsu 3 , Takayuki Yamamoto 3, Kazuhiko Yanai 1, Hiroyuki Arail, Yukitsuka Kudo 1,2, Tohru Sawada 2. 1Tohoku University School of
Medicine, Sendal, Japan; 2BF Research Institute Inc., Suita, Japan; 3Fukushimura Hospital, Toyohashi, Japan. Contact e-mail: oka @mail.rains,tohoku.ae.jp Background: Senile plaques (SPs) and neurofibrillary tangles (NFTs) are two major neuropathological features of Alzheimer's disease (AD) that may precede cognitive decline. Noninvasive detection of these pathological hallmarks could be useful, not only for preclinical diagnosis of AD but also for pharmacological evaluation of anti-amyloid therapy. Objective(s): To develop novel positron emission tomography (PET) imaging agents with high binding specificity for AD-related pathology, we evaluated in
vitro and in vivo binding profiles of novel lipophilic compounds to SPs and NFTs. Methods: Styrylbenzoxazole and styrylquinoline derivatives were examined. Binding selectivity for SPs and NFTs were evaluated by neuropathological staining of postmortem AD brains. Blood-brain barrier permeabilities were assessed using normal mice. In vivo binding ability of the compounds to brain SPs is also assessed by intravenous administration of radiolabeled compound to APP transgenic mice. Results: Many of the examined compounds showed a high binding affinity for both synthetic Abetal-40 and Abetal-42 aggregates. BF-168, a styrylbenzoxazole derivative, displayed distinct staining of neuritic and diffuse SPs and NFTs in the AD brain sections. A biodistribution study of styrylbenzoxazole and styrylquinoline derivatives in normal mice exhibited excellent brain uptakes (3.9-8.2% injected dose/g at 2 min post injection) and good clearance in normal brain tissue (0.22-3.8% injected dose/g at 30 min post injection). Intravenous injection of BF-168 in PS1/APP transgenic mice resulted in specific in vivo labeling to SPs in the brain. Autoradiographic study also demonstrated specific in vivo labeling of brain amyloid deposits in APP transgenic mice by intravenously administered [18F]BF-168, in contrast to no accumulation in a wildtype mouse brain. Furthermore, we have recently developed novel lSF-labeled benzoxazole-derivative compound that can successfully minimize nonspecific retention in the white matter region. Optimization of pharmacokinetic and toxicological properties is now in progress. Conclusions: These results suggest that [aSF]BF-168 and its derivatives are potential candidates as a PET tracer of imaging brain pathology in AD patients.
•
IMPACT OF MRI WHITE MATTER HYPERINTENSITIES ON PREPULSE INHIBITION IN A MIXED ELDERLY POPULATION
Gunhild Waldemar* 1, Anne Mette Hejl 1, Lise C. Salem 1, Ellen Garde 2, Anne Metre Leffers 2, Olaf B. Panlson 2. 1Memory Disorders Research
Unit, Dept. of Neurology; Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark; 2Danish Research Centerfor Magnetic Resonance, Copenhagen University Hospital, Hvidovre, Copenhagen, Denmark. Contact e-mail: [email protected] Background: Prepulse inhibition (PPI) of the startle response, a measure for sensorimotor gating, has previously been investigated in patients with Mild Cognitive Impairment (MCI) and Alzheimer's disease (AD). PPI did not differ from that of healthy controls, and exhibited a high and unexplained interindividual variability in both patients and healthy controls. Unspecific white-matter hyperintensities (WMH) are commonly found on magnetic resonance imaging (MRI) in elderly patients with and without dementia. Objectives: The aim of this study was to investigate to which extent interindividual variability in PPI may be explained by the presence and severity of WMH. Methods: The study included 39 patients (mean age 74.9, range 62-83) with early AD or MCI and 53 healthy controls (mean age 71.2, range 61-85). All participants underwent brain MRI and PPI examination. For MRI a Siemens 1.5 T Vision scanner was used. Visual rating was performed on conventional fluid-attenuated inversion recovery (FLAIR). WMH were defined as high signal areas of the subcortical and periventricular white matter and the presence rated as none (0), mild (1), moderate to severe (2-3) according to the modified Fazekas scale. PPI was investigated with a passive acoustic paradigm using a strong stimulus of 40 ms 115 dB burst presented alone or briefly after a prepulse stimulus (85 dB noise burst, 20 ms in duration). The interval between prepulse and the strong stimulus (ISI) was 30, 60, or 120 ms. Results: Twenty percent had no WMH, 53% had mild, and 27% had moderate to severe WMH. Increasing latency to peak of PPI was identified with increasing WMH (p = 0.02). A trend for inverse doseresponse association between PP[ amplitude and the degree of WMH was found for IS160 and 120 ms. There was no difference in PPI between healthy subjects and patients with AD or MCI. Conclusion: WMH may account for some of the high variability found in PPI possibly due to an affection of the fronto-striatal brain circuits regulating PPI. Further investigations are needed to study the high variability of PPI in order to characterize and fully understand sensorimotor gating in neurodegenerative diseases.
•
NEURONAL ASSAY BASED ON DEVELOPMENTALLY INDUCIBLE EXPRESSION OF ALZHEIMER'S TAU, DESIGNED FOR SCREENING OF AD THERAPEUTICS
Peter Fifipcik . I , Miroslava Pevalova 2 , Oskar Smrzka 1, Michal Novak 2'1 .
1Axon-Neuroscience GmbH, Vienna, Austria; 21nstitute of Neuroimmunology, Bratislava, Slovakia. Contact e-mail: fiIipcik@ axon-neuroscience.at Background. Our transgenic rat model of AD showed that, expression of Alzheimer's truncated tan (AT) is causing formation of neurofibrillary degeneration similar to that observed in human AD diseased brain. Targeting of events leading to neurofibrillary pathology represents a valuable approach to treatment of Alzheimer's disease. Objective. Developing a bioassay, that is based on transgenic neurons expressing diseased forms of the tau protein. This allows screening for compounds that eliminate and prevent the deleterious effect of Alzheimer's tan. Methods, Neurons from different brain regions (cortex, hippocampus, brain stem) of transgenic and nontransgenic embryos were isolated and grown in serum free Neurobasal medium. Pure neuronal cultures and neuron-gila co-cultures were produced in parallel. Viability and cell death were determined. Western blot analysis and immunofluorescence microscopy, was performed using a panel of mAb's (DC25, Tau-1, AT-8, PHF1, MAP1, CytC GFAP). Further changes in cell morphological and organell distribution were analysed using eonfocal microscopy and videomieroscopy. Results. Transgenic primary neurons were characterized as follows: 1. Expression of AT is inducible, which permits to determine target specificity of tested compounds under controlled conditions. 2. Neurons derived from transgenic embryos exhibit altered accumulation of phosphorylated tau protein and impaired distribution of organelles. 3. Cortical neurons from transgenic rats are significantly more vulnerable to oxidative damage induced extra or intracellularly when compared to neurons of nontransgenic controls. In the assay system the viability of transgenic neurons was decreased (up to 74%) when compared to wild type neurons. Conclusion. This primary cell assay system has been established and applied for screening and validating compounds which are able to alleviate the neurodegenerative effect of Alzheimer's tau. The assay can also be extended for determination of neurotrophic effects or oxidative stress in combination with Alzheimer's tau expression.
•
TISSUE SLICE CULTURES FROM HUMAN BRAIN AUTOPSIES AND BIOPSIES: ALZHE1MER'S DISEASE AND OTHER NEUROLOGICAL DISORDERS
Ronald W. Verwer* I, Rawien Balesar 1, Lei Wu 2,1, Elisabeth F. Boiten 1, Arja A. Sluiter 1, Clemens M. Dirven 3, David E Noske 3, Robert E. Baker I , Rivka Ravid 4, Jiang-ning Zhou 2, Dick E Swaab I . 1Netherlands Institute
for Brain Research, Amsterdam, Netherlands; 2Department of Neurobiology, University of Science and Technology of China, Hefei, Anhui, China; 3Department of Neurosurgery, VU University Medical Center, Amsterdam, Netherlands; 4Netherlands Brain Bank, Amsterdam, Netherlands. Contact e-mail: [email protected] Background: We have previously shown that neurons in cultured postmortem human brain slices respond to neurotrophic factors and can express
$265
transgenes after several weeks in vitro. Viable neurons were observed in the presence of massive Alzheimer pathology (Verwer etal., FASEB J. 16: 5460, 2002). Objective(s): First, extend the characterization of the functional activity of neurons in the postmortem human brain cultures with electrophysiological recordings. Second, study the properties of endogenous/exogenous neural precursor cells (NPC) in cultures of degenerating human CNS tissue. Methods: Brain tissue slices of hippocampus, parahippocampal gyrus and motor cortex, obtained at rapid autopsies of control subjects and Alzheimer patients or obtained after surgical resection for treatment of intractable epilepsy, were cultured in chemically defined serum-free medium. Electrical recordings were performed using single electrodes and multi-electrode arrays. Neurospheres from rat embryos and adult human tissue were isolated according to existing protocols in the literature. Neurospheres (rat or human) or human brain slices containing endogenous neural precursor cells were co-cultured with slices from AD patients. Live/dead staining was used to assess the general viability of the cells in the preparations. Routine immunostaining with markers for neurons, glial cells and Alzheimer pathology was carried out to evaluate the morphological features of the tissues. Markers for early developmental stages were used to verify the nature of precursor cell preparations and the presence/absence of endogenous precursor cells in tissue slices. Results: Neurons in hippocampal slice cultures exhibited sparse electrical activity (both membrane activity and spikes) for up to 3 weeks. Probably due to selective ,mlnerability of the CA areas to ischemic conditions, electro-physiological signals were predominantly observed in the hilus area. In cortex slices from some patients endogenous NPC's were present in cortical layer I and in white matter. Occasionally, these cells were omnipresent. Co-cultures of neurospheres or NPC containing slices with host-slices from AD patients showed migration of NPC's along blood vessels into the host tissue. Conclusions: Cultures of human adult brain tissue slices obtained at rapid autopsy or at operations have a great potential for both fundamental research and the development of therapeutic and diagnostic strategies.
•
NEUROPROTECTIVE EFFECT OF CEREBROLYSIN ON ORGANOTYPIC HIPPOCAMPAL BRAIN SLICES IN VITRO
Birgit Hutter-Paier* 1, Catherine Riley t, Edith Doppler 2, Herbert Mrssler 3, Manfred Windisch 1 1jSW_Research ' Graz, Austria; 2EBEWE Pharma Nfg.
KG, Unterach, Austria; 3EBEWE Pharma GmbH Nfg. KG, Unterach, Austria. Contact e-mail: [email protected] For many years Cerebrolysin (Cere, EBEWE-Pharma Austria) has been reported to have neurotrophic and neuroprotective potential as comparable to naturally occurring growth factors like NGF or BDNF. Some of the in vitro effects of this drag are well descaibed and discussed in context to neurodegenerative disorders like Alzheimer disease and also to acute neurological disease. In the present study an organotypic brain slice protocol was to develop and used to determine the neuroprotective effects of the peptidergic drug Cerebrolysin in a glutamate lesion paradigm. Concomitant excitotoxic over-stimulation due to excess release of the excitatory neurotransmitter glutamate is one key event in ischemia. It increases intracellular calcium levels, over-activates different protein kinases and triggers enzyme reactions which finally result in excessive production of oxygen free radicals, damage of cell membranes and ultimately neuronal death. All of these measures have also been mentioned in relation to more chronic neurodegenerative diseases like Alzheimer disease. The study focused on the effects of Cere on both necrotic and apoptotic cell death after glutamate lesion. The effects of Cere (401~l/ml medium) on glutamate lesioned hippocampal slices were evaluated qualitatively and quantitatively at multiple time points before, during and after the lesion. Slices were viewed microscopically and photographed. Fluorescent readings were taken at 485 nm for Yoprol and at 520 nm for PI. Cere was added before and after the lesion as well as after the lesion alone and remained with the brain slices for distinct time periods. Our results show that the most pronounced drug effects were seen on slices that were treated with Cere both prior to and after glutamate lesioning, but that post treatment immediately after the lesion was also able to counteract neurodegeneration due to the addition of
$266
Poster Session P2: Diagnosis and Disease Progression - Neuroimaging
glutamate. In both cases Cere appears to inhibit apoptosis to a greater extent than necrosis. These positive neuroprotective effects could be relevant for the treatment of acute, as well as, chronic neurodegenerative diseases.
Poster Session P2: D i a g n o s i s and Disease Progression Neuroimaging ~ 4 ]
LEARNING AND MEMORY IN INCIPIENT AD: A FDG PET AND FMRI STUDY
Peter Schoenknecht* 1, Aoife Hunt I , Marcus Hentze 2, Freddy Giesel 3, Essig Marco 3, Pantel Johannes 4, Haberkorn Uwe 5, Johannes Schroeder 1.
1Ruprecht Karls University Heidelberg, Heidelberg, Germany; 2Ruprecht Karls University Heidelberg, Department Nuclear Medicine, Germany; 3German Cancer Research Center, Heidelberg, Germany; 4Goethe University Frankfurt a. M., Heidelberg, Germany; 5Ruprecht Karls University Heidelberg, Department Nuclear Medicine, Germany. Contact e-mail: [email protected] Background: Recent studies have demonstrated that older individuals with subclinical cognitive impairments have a higher risk for developing dementia. In several follow-up studies, patients with "mild cognitive impairment (MCI)" were found to develop Alzheimer's disease (AD) in their later life. In order to characterise subjects at risk in the early stages of the disease FDG-PET has to be investigated in subjects with MCI compared to cognitively unimpaired controls. Following the hypothesis of impaired encoding processes in subjects at risk explicit memory functions warrant further investigation. Methods: 60 subjects admitted to the Section for Geriatric Psychiatry underwent thorough clinical and neuropsychological investigation und were investigated by FDG-PET or MRI. In the functional MRI paradigm applied in a subgroup of MCI subjects brain activation during an episodic memory task (words) was studied. Results: 40 subjects were diagnosed as AD and 20 were characterised as MCI. Comparison of patients with AD and eognitively unimpaired controls revealed a significantly reduced FDG uptake in the rigth and left temporoparietal association cortex in AD patients (p < 0.05). MCI patients showed in comparison to cognitively unimpaired controls a significantly reduced FDG uptake in the temporal and parietal association cortex (p < 0.05), too. In MCI patients who underwent a fMRI word encoding task, temporal, frontal, and parietal cortex activation during word encoding was found. Conclusions: Results of this study indicate that AD can be characterised by significantly reduced FDG uptake in the temporoparietal association cortex. Since patients with MCI show a similar pattern of reduced FDG uptake in the temporal and parietal association cortex this condition might represent an early stage of the disease. Nevertheless, the temporal, frontal, and parietal cortex activation during word encoding provides insight in the explicit memory function in patients with MCI which has to be investigated further.
~-~-]
NOVEL 18F-LABELED PET TRACER FOR DETECTING AMYLOID PLAQUES AND NEUROFIBRILLARY TANGLES IN THE BRAIN
Nobuyu!d Okamura* 1,2, Takahiro Suemoto 2, Hiroshi Shimadzu 2, Masako Suzuki 2, Tsuyoshi Shiomitsu 2, Hiroyasu Akatsu 3 , Takayuki Yamamoto 3, Kazuhiko Yanai 1, Hiroyuki Arail, Yukitsuka Kudo 1,2, Tohru Sawada 2. 1Tohoku University School of
Medicine, Sendal, Japan; 2BF Research Institute Inc., Suita, Japan; 3Fukushimura Hospital, Toyohashi, Japan. Contact e-mail: oka @mail.rains,tohoku.ae.jp Background: Senile plaques (SPs) and neurofibrillary tangles (NFTs) are two major neuropathological features of Alzheimer's disease (AD) that may precede cognitive decline. Noninvasive detection of these pathological hallmarks could be useful, not only for preclinical diagnosis of AD but also for pharmacological evaluation of anti-amyloid therapy. Objective(s): To develop novel positron emission tomography (PET) imaging agents with high binding specificity for AD-related pathology, we evaluated in
vitro and in vivo binding profiles of novel lipophilic compounds to SPs and NFTs. Methods: Styrylbenzoxazole and styrylquinoline derivatives were examined. Binding selectivity for SPs and NFTs were evaluated by neuropathological staining of postmortem AD brains. Blood-brain barrier permeabilities were assessed using normal mice. In vivo binding ability of the compounds to brain SPs is also assessed by intravenous administration of radiolabeled compound to APP transgenic mice. Results: Many of the examined compounds showed a high binding affinity for both synthetic Abetal-40 and Abetal-42 aggregates. BF-168, a styrylbenzoxazole derivative, displayed distinct staining of neuritic and diffuse SPs and NFTs in the AD brain sections. A biodistribution study of styrylbenzoxazole and styrylquinoline derivatives in normal mice exhibited excellent brain uptakes (3.9-8.2% injected dose/g at 2 min post injection) and good clearance in normal brain tissue (0.22-3.8% injected dose/g at 30 min post injection). Intravenous injection of BF-168 in PS1/APP transgenic mice resulted in specific in vivo labeling to SPs in the brain. Autoradiographic study also demonstrated specific in vivo labeling of brain amyloid deposits in APP transgenic mice by intravenously administered [18F]BF-168, in contrast to no accumulation in a wildtype mouse brain. Furthermore, we have recently developed novel lSF-labeled benzoxazole-derivative compound that can successfully minimize nonspecific retention in the white matter region. Optimization of pharmacokinetic and toxicological properties is now in progress. Conclusions: These results suggest that [aSF]BF-168 and its derivatives are potential candidates as a PET tracer of imaging brain pathology in AD patients.
•
IMPACT OF MRI WHITE MATTER HYPERINTENSITIES ON PREPULSE INHIBITION IN A MIXED ELDERLY POPULATION
Gunhild Waldemar* 1, Anne Mette Hejl 1, Lise C. Salem 1, Ellen Garde 2, Anne Metre Leffers 2, Olaf B. Panlson 2. 1Memory Disorders Research
Unit, Dept. of Neurology; Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark; 2Danish Research Centerfor Magnetic Resonance, Copenhagen University Hospital, Hvidovre, Copenhagen, Denmark. Contact e-mail: [email protected] Background: Prepulse inhibition (PPI) of the startle response, a measure for sensorimotor gating, has previously been investigated in patients with Mild Cognitive Impairment (MCI) and Alzheimer's disease (AD). PPI did not differ from that of healthy controls, and exhibited a high and unexplained interindividual variability in both patients and healthy controls. Unspecific white-matter hyperintensities (WMH) are commonly found on magnetic resonance imaging (MRI) in elderly patients with and without dementia. Objectives: The aim of this study was to investigate to which extent interindividual variability in PPI may be explained by the presence and severity of WMH. Methods: The study included 39 patients (mean age 74.9, range 62-83) with early AD or MCI and 53 healthy controls (mean age 71.2, range 61-85). All participants underwent brain MRI and PPI examination. For MRI a Siemens 1.5 T Vision scanner was used. Visual rating was performed on conventional fluid-attenuated inversion recovery (FLAIR). WMH were defined as high signal areas of the subcortical and periventricular white matter and the presence rated as none (0), mild (1), moderate to severe (2-3) according to the modified Fazekas scale. PPI was investigated with a passive acoustic paradigm using a strong stimulus of 40 ms 115 dB burst presented alone or briefly after a prepulse stimulus (85 dB noise burst, 20 ms in duration). The interval between prepulse and the strong stimulus (ISI) was 30, 60, or 120 ms. Results: Twenty percent had no WMH, 53% had mild, and 27% had moderate to severe WMH. Increasing latency to peak of PPI was identified with increasing WMH (p = 0.02). A trend for inverse doseresponse association between PP[ amplitude and the degree of WMH was found for IS160 and 120 ms. There was no difference in PPI between healthy subjects and patients with AD or MCI. Conclusion: WMH may account for some of the high variability found in PPI possibly due to an affection of the fronto-striatal brain circuits regulating PPI. Further investigations are needed to study the high variability of PPI in order to characterize and fully understand sensorimotor gating in neurodegenerative diseases.