Detection of oligomeric β-amyloid peptide in biological samples using a singlesite monoclonal antibody sandwich enzyme-linked immunoabsorbant assay

s90

Poster

COMBINATION OF CEREBROSPINAL FLUID TAU, AB40 AND 1405( AB42 ANALYSES IN THE DIAGNOSIS OF ALZHEIMER’S DISEASE Two of

Tapiolrr,

Kuopio.

Urliv

Devrlopm~nral Finland:

of Kuopio,

Kuopio

Finland:

Finland;

Pankaj

D

Kuopio

Disabilities,

Mnarit

New

Lrhtovirtn.

York;

Hilkkn

Tuulu

Mehta,

Irina

Soininen.

Pwttila,

Institute

1 Alaj”,-ofi

CJniv und I/nil’ Hasp

for

Basic

Kuopio

Research

in

Univ Ho.sp, Kuopio

Univ and Univ Hasp of Kuopio.

Kuopio

Finland

A biomarker for Alzheimer’s disease (AD) would be valuable as a diagnostic tool for Alzheimer’s diseaw. Cerebrospinal fluid (CSF) tau concentration is increased and P-amyloid 42 (AP42) decreased in AD. There is, however, overlap in the levels of these biomarkers between AD and controls and especially between AD and other dementias. For diagnostic use of biomarkers high sensitivity and specificity are required, which may be achieved by combining the results of different analyses. Our study included 121 patients with AD including 41 neuropathologically confirmed AD cases, 27 patients with other dementias, and 39 non-demented neurological controls. CSF tau, A@42 and AP40 levels were quantified using ELBA assays. The results of tau and AP42 analyses were combined, and A@ratio (AP40IAP42) and AD index (tau x AP40/AP42) were calculated to investigate the diagnostic use of these blomarkers. CSF tau level was increased (p
[406(

THE IMPORTANCE OF MITOCHONDRIAL DAMAGE IN ALZHEIMER’S DISEASE VARIES ACCORDING TO APOE GENOTYPE

C;ury E Gibson, Vuhram Ch Park.

Cornell

C Mobs, Bronx ut Burke Plains,

Cornell

Haroutunian.

Med

Med

Bronx

Mrd

Co11 at Burke Veteran

Co11 ut Burke

Veteran

Affairs

Research

Insr.

Affairs Med

Med

Research

Mrd

Ctr. Bronx.

Research

Med Ctr, Bronx, White

Pluins.

Inst,

Inst.

White

Plains,

NY; Hui Zhang,

White Plains,

ON;

NY: Rex K -F Sheu, Cornell

NY: John

P Blass.

Cornell

NY; Lurry

Richard Mrd

Unrv,

Co11 White

NY

In Alzheimer Disease’s (AD), brain metabolism is diminished as is the activity of the cr-ketoglutarate dehydrogenase complex (KGDHC), a mitochondrial enzyme. The significance of these metabolic changes to symptoms is debated. We therefore compared the relationship of clinical disability (CDR) to mitochondrial damage (KGDHC deficiency), to amyloid plaques, and to neuritic tangles. In AD patients who carried the epsilon 4 allele of the apolipoprotein E gene (APOE4). CDR score correlated better (p
piw/ Christian lmd,

AMYLOID AB40 CSF CONCENTRATIONS CORRELATE TO FRONTOTEMPORAL FRONTAL LOBE ATROPHY IN DEMENTIA Andersen,

Karolinskn

Ins,

M&m

Jensen,

Huddinge

Lars

Lannfelt.

Mann

Linduu,

Lurs-Oloj

Wah-

Sweden

Brain amyloid deposit< in Alzheimers disease (AD) consist of aggregated and non-aggregated amyloid Pprotein (AP) derived from cleavage of the amyloidpprecursor protein. The most common forms of APin AD amyloid deposlta end at positions 40 (AP40) and 42 (AP42). A@is secreted into cerebrospinal tluid (CSF). Llttle is known about APCSF level\ m non-AD neurodegenerative dementing

Presentution:

Biomarkers

II

diseases. Our aim was to measure CSF AP40 and A@42 concentrations in frontotemporal dementia patients and to correlate levels to the degree of frontal lobe atrophy, as assessed by magnetic resonance imaging (MRI) volumetry. We studied eleven patients that had been referred to our memory clinic for investigation of cognitive impairment. Clinically, patients fulfilled diagnostic criteria for frontotemporal dementia. All MRI examinations were performed using a Siemens I.5 T. The volumetric measurements were based on 3D magnetization prepared rapid gradient echo Tl weighted coronal images (repetition timexlO ms; echo timex4ms) with a slice thickness of 3 mm. Calculation of frontal lobe volumes started at the most anterior gyri and the anterior commisure defined the posterior border. Calculated volumes were corrected for differences in head sire. CSF samples were assayed for A@40 and A!342 with ELBA systems. CSF Ai340 concentrations were found to increase with the degree of frontal lobe atrophy. Linear regression analysis showed a significant relationship between CSF AP40 concentration and frontal lobe volume (r= -0.77, p
piEJ

M.

DETECTION OF OLIGOMERIC B-AMYLOU) PEPTIDE IN BIOLOGICAL SAMPLES USING A SINGLESITE MONOCLONAL ANTIBODY SANDWICH ENZYME-LINKED IMMUNOABSORBANT ASSAY

Des&e

R&y,

Watson,

Karl

Rraearch

L

Div,

Lori

Brown.

M Evans, Hurry

Ann Arbor,

Taraneh

LeVinr,

Huske.

Mark

Kathryn

R Emmerlin~.

Spiegel.

Charlotte

Parke-Davis

A

Phurm

MI

We can detect soluble oligomeric species of synthetic human P-amyloid peptides, API-42 and ApI-40, using a single monoclonal antibody to A!3 for both capture and detection in a sandwich ELBA. The monoclonal antibody 6ElO that binds to AP residues S-14 is used to capture, and biotinylated 6EI0 (b6ElO) to detect, A& The assay can measure as little as 2.5 nM of oligomerized ApI-42. Immediately measuring from 2.5 nM to 250 nM of freshly solubilized Apl-42 yields a signal that then triples as the peptide is incubate at 37°C for 24 h. The increased signal corresponds to detection of higher molecular weight species of AD (>40 kDa) by western blotting after gel electrophoresis and the presence of an AP peak running around 300 kDa on a superose 12 column. Similar results were obtained with Apl-40, but the time course of its oligomerization is slower. One can also substitute the monoclonal antibody 4G8 that recognizes the AP residues 17 to 24 in the assay. Moreover, the ELBA detects the oligomeriration of a variety of N-terminally truncated or modified AP peptides ending in residue 42, including rodent ApI-42. The presence of apparently oiigomeric species of AP were found in extracts of control and Alrheimer brain, in cerebrospinal fluid from control and AD patients, but not in rodent brain. Our results suggest that this simple ELBA may provide valuable insight into the early processess that lead to tibrillization of A!3 in Alzheimer brains, as well as a means of detecting and quantitating these oligomeric species of A@.

m Tuulu

PLASMA LEVELS OF AMYLOID B PROTEINS IN PATIENTS WITH DOWN SYNDROME DO NOT PREDICT DEVELOPMENT OF DEMENTIA A Pirttilu,

Institute Cent Itut,

for

Tero

Tupiola,

Basic Research, Ylojurvi

New

Univ

of Kuopio,

York, NY; Lena

Kuopio

Fmland:

Heikkila.

Tarmo

Pankaj

D Mehtu.

Kivimaki,

Ylinen

Finland

the brain neuropathology of Alzheimer’s disease is virtually present in all individuals with Down’s syndrome (DS) 40 years of age and older. The aim of the present study was to examine if there is a relationship between plasma levels of amyloid p proteins (AP40 and A@42) and cognitive decline in patients with DS. We examined cognitive status and collected plasma from 30 patients with DS at baseline and once a year thereafter for 5 years. Concentrations of plasma AP40 and A!342 were measured by sandwich enzyme linked itmnunosorbent assay (Arch. Neural. 2ooO: 100-105). The groups were compared with Kruskal-Wallis one-way ANOVA. mean gae at baseline was 50.9 years (31-64) in patients who developed dementia during the follow-up, and 43.0 years (26-52) in those who did not show cognitive decline. There were no significant differences in plasma levels of AP40 or AP42 at baseline between dementia (II= 19) and non-dementia (II= 11) groups (median 460 vs 500 pg/mL and 310 vs 255 pg/mL, respectively). Alao, the ratio between AP40/AP42 was similar in both groups (median 1.08 in demented vs 1.78 in non-demented). Plasma levels of Approteins were not related to age or apoE phenotype. Previous studies showed that AP protein levels were increased m some asymptomatic relatives of Alzheimer