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Albumin capacity to bind Aβ: In vitro fluid phase assay
POSTER PRESENTATION P1 molecules. The interaction of both labelled donor and acceptor molecules induced a fluorescence at 665nm proportional to the sAPP alpha level. A recombinant protein was used as standard. We investigated the CSF from 30 patients with AD, and 30 controls. CSFs were considered as AD profile according to tau protein, phosphorylated tau and Aß 1-42 results, as previously described (1). Excluded patients on the basis of CSF markers levels were considered as controls. Results: The test did not recognize recombinant sAPPß protein and Aß1-42 peptide. Sample dilutions (1/5, 1/10, 1/20) allowed to verify the response linearity. The test detected 3 ng/ml of sAPP alpha. 5 ml of sample was sufficient for the CSF quantification. Using this test, we could observed a significant increase of sAPP alpha in the CSF of 30 AD patients comparatively to 30 controls (AD:530 6 36 ng/ml; controls: 393 6 28 ng/ml; p < 0.01). Interestingly, sAPP alpha was significantly correlated with Aß levels in control CSFs only (r2 :0.31; p < 0.001). No significant correlations were observed between tau or phosphorylated tau and sAPP alpha levels in CSF. Conclusions: We developed a very sensitive test for the quantification of sAPP alpha levels in human CSF. Using this test, we observed an increase of sAPP alpha level in the CSF of AD patients in absence of correlation with other markers contrary to that observed in controls. It will be interesting to investigate a larger population of AD and Mild Cognitive Impairment patients to study the putative correlations of sAPP alpha levels with the biomarkers and parameters of the disease. 1: DumurgierJ et al, (2010) NeurobiolDis. 40: 456-459
P1-072
COMPARISON OF MEASUREMENTS OF MEDIAL TEMPORAL LOBE ATROPHY IN THE PREDICTION OF ALZHEIMER’S DISEASE IN SUBJECTS WITH MCI
Lies Clerx1, Laura van der Pol2, Daniel Rueckert3, Remco de Jong2, Ronald van Schijndel4, Descripa Study Group5, Frans R. J. Verhey6, Frederik Barkhof4, Robin Wolz7, Philip Scheltens8, Dirk Knol9, Pablo Lapuerta10, Pieter Jelle Visser11, Ineke van Rossum12, Leah Burns10, 1 Maastricht University; 2VU University Medical Centre, Amsterdam; 3 Imperial College London, London; 4VU University Medical Centre, Amsterdam; 5Alzheimer Centre, School for Mental Health and Neuroscience (MHeNS), University Medical Centre, Maastricht; 6Alzheimer Centre, School for Mental Health and Neuroscience (MHeNS), University Medical Centre, Maastricht; 7Imperial College London, London; 8VU University Medical Center, Amsterdam; 9VU University Medical Centre, Amsterdam; 10 Bristol-Myers Squibb, Wallingford; 11Alzheimer Centre, School for Mental Health and Neuroscience (MHeNS), University Medical Centre, Maastricht; 12VU University Medical Centre, Amsterdam. Background: Medial temporal lobe atrophy (MTA) predicts Alzheimer’s disease (AD) in subjects with mild cognitive impairment (MCI). MTA assessment may be used for the selection of MCI subjects in AD trials. There are several methods to assess MTA ranging from qualitative rating to manual volumetric measurements. Predictive accuracy may depend on the method and on whether the method requires standardisation of the scan protocol. The aim of the present study was to investigate which MTA assessment could best predict AD-type dementia in subjects with MCI in a multicentre and single-centre study. Methods: We selected subjects with MCI from 2 cohorts: the DESCRIPA multicentre study (n ¼ 279), which used different scanners and scan protocols and a single-centre study from the VU University medical centre (n ¼ 156), which used the same scanner and protocol. Four MRImeasures were compared: volumetric manual hippocampal measurement, volumetric automated atlas based hippocampal measurement (LEAP), qualitative visual rating, and volumetric measurement of the lateral ventricle. All volumetric measurements were corrected for intracranial volume and pooled for left and right side. Outcome was the area under the curve (AUC) of a ROC curve for predicting progression to AD-typedementia after 2 years. Results: In the multicentre study, the AUC was 0.72 for the manual hippocampal measurement, 0.72 for the LEAP measurement, 0.67 for the qualitative rating, and 0.56 for the lateral ventricle measurement. In the single-centre study, the AUC was 0.67 for the manual hippocampal measurement, 0.69 for the LEAP measurement, 0.61 for the qualitative rating, and
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0.61 for the lateral ventricle measurement. The best cut-point on the LEAP volume to predict AD-type dementia as determined by the Youden index was similar in the multicentre study (5374 mm3) and single-centre study (5431 mm3). Conclusions: Hippocampal volume predicts AD better than a qualitative rating or lateral ventricle volume. All measures yielded similar predictive accuracy in the multicentre and single-centre study. The LEAP measurement may be preferred in multicentre studies as it demonstrated good accuracy in discriminating between MCI progressors and non-progressors. Moreover, the measurement was stable across different cohorts, was automated, and was able to determine consistent cut points.
P1-073
ALBUMIN CAPACITY TO BIND Ab: IN VITRO FLUID PHASE ASSAY
Montse Costa, Ana Maria Ortiz, Juan Ignacio Jorquera, Instituto Grifols, S.A., Parets del Valles. Background: About 90% of plasma beta-amyloid (Aß) may be bound to albumin (1). We showed (2) that therapeutic albumin binds synthetic Aß peptides. In an ongoing clinical trial (3), Alzheimer disease patients’ endogenous albumin is partially replaced with Albumin GrifolsÒ through a plasma exchange procedure in order to alter the potential equilibrium between Aß in plasma and Aß in the cerebrospinal fluid. We aim to investigate whether Grifols’ therapeutic albumin binds s in a fluid phase in vitro experiment. Methods: A fixed amount of sAß peptide (80 pg/ml) was added to increasing protein concentrations (0 to 45 mg/ml) of different samples: Grifols’ therapeutic albumin, plasma and a sample mainly containing albumin and gammaglobulins. These mixtures were incubated overnight at 37 C before analysing the accessible Aß content by a commercial ELISA (hAmyloid ß40/ß42 ELISA (HS) (The Genetics Co.), previously validated in our laboratory. The percentage of Aß recovery was calculated as the Aß measured (pg/ ml) in each sample with regard to the Aß measured in TTBS buffer. Results: Fluid phase experiments (n ¼ 4) showed a recovery between 59-78% of measurable sAß 1-42 after incubation with therapeutic albumin (45 mg/ml). However, sAß1-40 does not appear to interact with albumin in this experimental setting (recoveries ¼96%, n ¼ 2). The analysis of plasma samples (n ¼ 3), at the same protein concentration, showed a lower recovery of the added sAß1-42 (30-48%), as expected since other proteins in plasma are also able to interact with Aß (4). When testing another sample (n ¼ 2), mainly containing albumin and gammaglobulins, a recovery between 42.5-53% at 45 mg/ml protein concentration was obtained, confirming ‘in vitro’ the fact that gammaglobulins present in plasma samples are able to interact with sAß 1-42. Conclusions: A fluid phase ‘in vitro’ experiment to measure the capacity to bind Aß has been set up. These results confirm that Grifols’ therapeutic albumin is able to bind ‘in vitro’ an Aß peptide with the human sequence. (1): Biere AL et al J Biol Chem, 271: 32916, 1996.(2): Costa M et al Alzheimer’s & Dementia, 5 (Suppl 4): P417, 2009.(3): Boada M et al Drugs News Perspect, 22: 325339, 2009.(4): Bohrmann B et al. J Biol Chem, 274:15990-15995, 1999.
P1-074
TRACKING PROGRESSION FROM MILD COGNITIVE IMPAIRMENT TO ALZHEIMER’S DISEASE USING MULTIVARIATE BIOMARKERS AND PATTERN CLASSIFICATION
Wei Wen1, Yue Cui2, Bing Liu3, Xiantong Zhen4, Ming Fan3, Suhuai Luo5, Tao Liu6, Wanlin Zhu7, Mira Park6, Tianzi Jiang3, Jesse Jin6, 1Randwick, Sydney; 2University of Newcastle, Australia, Newcastle; 3Institute of Automation, Chinese Academy of Sciences, Beijing; 4Institute of Automation, Chinese Academy of Sciences, Beijing; 5University of Newcastle, Newcastle; 6University of Newcastle, Newcastle; 7University of New South Wales, Sydney. Background: Prediction of conversion from mild cognitive impairment (MCI) to Alzheimer’s disease (AD) has attracted significant attention recently. Most investigations have used a single modality of data. In the present study, multiple features from different modalities of data, including structural MRimaging (MRI), cognitive measures (CM) and cerebrospinal fluid (CSF) biomarkers, were examined in the Alzheimer’s Disease
P1-072
COMPARISON OF MEASUREMENTS OF MEDIAL TEMPORAL LOBE ATROPHY IN THE PREDICTION OF ALZHEIMER’S DISEASE IN SUBJECTS WITH MCI
Lies Clerx1, Laura van der Pol2, Daniel Rueckert3, Remco de Jong2, Ronald van Schijndel4, Descripa Study Group5, Frans R. J. Verhey6, Frederik Barkhof4, Robin Wolz7, Philip Scheltens8, Dirk Knol9, Pablo Lapuerta10, Pieter Jelle Visser11, Ineke van Rossum12, Leah Burns10, 1 Maastricht University; 2VU University Medical Centre, Amsterdam; 3 Imperial College London, London; 4VU University Medical Centre, Amsterdam; 5Alzheimer Centre, School for Mental Health and Neuroscience (MHeNS), University Medical Centre, Maastricht; 6Alzheimer Centre, School for Mental Health and Neuroscience (MHeNS), University Medical Centre, Maastricht; 7Imperial College London, London; 8VU University Medical Center, Amsterdam; 9VU University Medical Centre, Amsterdam; 10 Bristol-Myers Squibb, Wallingford; 11Alzheimer Centre, School for Mental Health and Neuroscience (MHeNS), University Medical Centre, Maastricht; 12VU University Medical Centre, Amsterdam. Background: Medial temporal lobe atrophy (MTA) predicts Alzheimer’s disease (AD) in subjects with mild cognitive impairment (MCI). MTA assessment may be used for the selection of MCI subjects in AD trials. There are several methods to assess MTA ranging from qualitative rating to manual volumetric measurements. Predictive accuracy may depend on the method and on whether the method requires standardisation of the scan protocol. The aim of the present study was to investigate which MTA assessment could best predict AD-type dementia in subjects with MCI in a multicentre and single-centre study. Methods: We selected subjects with MCI from 2 cohorts: the DESCRIPA multicentre study (n ¼ 279), which used different scanners and scan protocols and a single-centre study from the VU University medical centre (n ¼ 156), which used the same scanner and protocol. Four MRImeasures were compared: volumetric manual hippocampal measurement, volumetric automated atlas based hippocampal measurement (LEAP), qualitative visual rating, and volumetric measurement of the lateral ventricle. All volumetric measurements were corrected for intracranial volume and pooled for left and right side. Outcome was the area under the curve (AUC) of a ROC curve for predicting progression to AD-typedementia after 2 years. Results: In the multicentre study, the AUC was 0.72 for the manual hippocampal measurement, 0.72 for the LEAP measurement, 0.67 for the qualitative rating, and 0.56 for the lateral ventricle measurement. In the single-centre study, the AUC was 0.67 for the manual hippocampal measurement, 0.69 for the LEAP measurement, 0.61 for the qualitative rating, and
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0.61 for the lateral ventricle measurement. The best cut-point on the LEAP volume to predict AD-type dementia as determined by the Youden index was similar in the multicentre study (5374 mm3) and single-centre study (5431 mm3). Conclusions: Hippocampal volume predicts AD better than a qualitative rating or lateral ventricle volume. All measures yielded similar predictive accuracy in the multicentre and single-centre study. The LEAP measurement may be preferred in multicentre studies as it demonstrated good accuracy in discriminating between MCI progressors and non-progressors. Moreover, the measurement was stable across different cohorts, was automated, and was able to determine consistent cut points.
P1-073
ALBUMIN CAPACITY TO BIND Ab: IN VITRO FLUID PHASE ASSAY
Montse Costa, Ana Maria Ortiz, Juan Ignacio Jorquera, Instituto Grifols, S.A., Parets del Valles. Background: About 90% of plasma beta-amyloid (Aß) may be bound to albumin (1). We showed (2) that therapeutic albumin binds synthetic Aß peptides. In an ongoing clinical trial (3), Alzheimer disease patients’ endogenous albumin is partially replaced with Albumin GrifolsÒ through a plasma exchange procedure in order to alter the potential equilibrium between Aß in plasma and Aß in the cerebrospinal fluid. We aim to investigate whether Grifols’ therapeutic albumin binds s in a fluid phase in vitro experiment. Methods: A fixed amount of sAß peptide (80 pg/ml) was added to increasing protein concentrations (0 to 45 mg/ml) of different samples: Grifols’ therapeutic albumin, plasma and a sample mainly containing albumin and gammaglobulins. These mixtures were incubated overnight at 37 C before analysing the accessible Aß content by a commercial ELISA (hAmyloid ß40/ß42 ELISA (HS) (The Genetics Co.), previously validated in our laboratory. The percentage of Aß recovery was calculated as the Aß measured (pg/ ml) in each sample with regard to the Aß measured in TTBS buffer. Results: Fluid phase experiments (n ¼ 4) showed a recovery between 59-78% of measurable sAß 1-42 after incubation with therapeutic albumin (45 mg/ml). However, sAß1-40 does not appear to interact with albumin in this experimental setting (recoveries ¼96%, n ¼ 2). The analysis of plasma samples (n ¼ 3), at the same protein concentration, showed a lower recovery of the added sAß1-42 (30-48%), as expected since other proteins in plasma are also able to interact with Aß (4). When testing another sample (n ¼ 2), mainly containing albumin and gammaglobulins, a recovery between 42.5-53% at 45 mg/ml protein concentration was obtained, confirming ‘in vitro’ the fact that gammaglobulins present in plasma samples are able to interact with sAß 1-42. Conclusions: A fluid phase ‘in vitro’ experiment to measure the capacity to bind Aß has been set up. These results confirm that Grifols’ therapeutic albumin is able to bind ‘in vitro’ an Aß peptide with the human sequence. (1): Biere AL et al J Biol Chem, 271: 32916, 1996.(2): Costa M et al Alzheimer’s & Dementia, 5 (Suppl 4): P417, 2009.(3): Boada M et al Drugs News Perspect, 22: 325339, 2009.(4): Bohrmann B et al. J Biol Chem, 274:15990-15995, 1999.
P1-074
TRACKING PROGRESSION FROM MILD COGNITIVE IMPAIRMENT TO ALZHEIMER’S DISEASE USING MULTIVARIATE BIOMARKERS AND PATTERN CLASSIFICATION
Wei Wen1, Yue Cui2, Bing Liu3, Xiantong Zhen4, Ming Fan3, Suhuai Luo5, Tao Liu6, Wanlin Zhu7, Mira Park6, Tianzi Jiang3, Jesse Jin6, 1Randwick, Sydney; 2University of Newcastle, Australia, Newcastle; 3Institute of Automation, Chinese Academy of Sciences, Beijing; 4Institute of Automation, Chinese Academy of Sciences, Beijing; 5University of Newcastle, Newcastle; 6University of Newcastle, Newcastle; 7University of New South Wales, Sydney. Background: Prediction of conversion from mild cognitive impairment (MCI) to Alzheimer’s disease (AD) has attracted significant attention recently. Most investigations have used a single modality of data. In the present study, multiple features from different modalities of data, including structural MRimaging (MRI), cognitive measures (CM) and cerebrospinal fluid (CSF) biomarkers, were examined in the Alzheimer’s Disease