Confounding factors influencing amyloid Beta concentration in cerebrospinal fluid.
Author(s): Bjerke M, Portelius E, Minthon L, Wallin A, Anckarsäter H, Anckarsäter R, Andreasen N, Zetterberg H, Andreasson U, Blennow K
Publication: Int J Alzheimers Dis, 2010, Vol. 2010, Page
PubMed ID: 20798852 PubMed Review Paper? No
Purpose of Paper
Conclusion of Paper
Studies
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Study Purpose
The purpose of this study was to determine the effects of method of analysis on the measurement of ABeta42 in CSF from Alzheimer's disease patients and healthy individuals.
Summary of Findings:
All assays except the hAmyloid Beta42 ELISA showed significant differences in ABeta42 concentrations between Alzheimer's disease patients and healthy individuals when either CSF or CSF diluted in buffer with detergent was assayed. While absolute measurements of ABeta42 concentrations by the various assays showed large differences, correlations between all pairs of assays were strong for both diluted and undiluted CSF (0.53-0.98). The authors suggest that different sources for the ABeta42 standards used for calibration of the various assays may account for the different measurements.
Biospecimens
Preservative Types
- Frozen
Diagnoses:
- Alzheimer's Disease
- Normal
Platform:
Analyte Technology Platform Protein Immunoassay Protein ELISA Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Immunoassay Specific Technology platform INNO-BIA AlzBio3
INNO-BIA plasma ABeta forms
MSD Abeta Triplex Ultra-Sensitive Assay
hAmyloid Beta42 ELISA
INNOTEST Beta-amyloid1-42 ELISA
ELISA Specific Detection method 3D6 (amino acid 1-5)
48G (amino acid 17-24)
Biospecimen Aliquots and Components Biospecimen components CSF
CSF diluted in buffer with detergent
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Study Purpose
The purpose of this study was to determine the effects of heat denaturation, centrifugation, storage conditions, storage temperature and duration, delayed freezing, freezing method, and thaw temperature on the measurement of ABeta42 in CSF from Alzheimer's disease patients and healthy individuals.
Summary of Findings:
Storage of CSF in polystyrene or glass tubes led to decreases in ABeta42 when compared to levels measured in CSF stored in polypropylene tubes, however the decrease was only significant for polystyrene tubes. Running CSF through a lumbar catheter or a lumbar pressure meter catheter had no effects on measured ABeta42 concentrations. Room temperature storage for up to 24 h, one freeze-thaw cycle, and incubation at room temperature or 4 degrees C for 4, 24, or 72 h prior to freezing had no significant effects on ABeta42 concentrations. Furthermore, thawing temperature, freezing method, type of freezer, frozen storage temperature (-20 or -80 degrees C), and collection temperature (room temperature or on ice), had no significant influences on ABeta42 concentration. The coefficient of variation (CV) for ABeta42 concentration when one CSF sample was measured weekly over the course of 26 months of storage at -80 degrees C was 7.5% and interassay CV was 7.7%. Centrifugation of CSF at room temperature or 4 degrees C decreased ABeta42 concentration compared to uncentrifuged specimens. Heat denaturation caused significant increases in CSF ABeta42 concentrations which were larger for Alzheimer's disease patients (71%) than for healthy individuals (42%).
Biospecimens
Preservative Types
- Frozen
- Other Preservative
- None (Fresh)
Diagnoses:
- Alzheimer's Disease
- Normal
Platform:
Analyte Technology Platform Protein ELISA Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Biospecimen Acquisition Pre-preservation condition 100 degrees C heating block for 10 min
100 degrees C heating block for 15 min
No heat denaturation
Storage Type of storage container Glass tubes
Polypropylene tubes
Polystyrene tubes
Run through a lumbar catheter
Run through a lumbar pressure meter catheter
Directly transferred to storage tube
Biospecimen Preservation Type of fixation/preservation Frozen
None (fresh)
Refrigeration
Storage Storage temperature Room temperature
4 degrees C
On ice
-20 degrees C
-80 degrees C
Storage Storage duration 0 h
3 h
4 h
24 h
3 d
At least 1 week
26 months
Biospecimen Preservation Cooling or freezing method/ rate Ethanol dry ice bath
Direct transfer to freezer
Storage Storage conditions Stable temperature freezer
Auto-defrosting freezer
Storage Thaw temperature/condition 4 degrees C
Room temperature
20 degrees C
Storage Freeze/thaw cycling 0 cycles
1 cycle
Biospecimen Aliquots and Components Centrifugation Not centrifuged
Multiple temperatures compared
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Study Purpose
The purpose of this study was to determine the effects of aliquot sequential collection, time of collection, blood contamination, and blood-brain barrier dysfunction on the measurement of ABeta42 in CSF from Alzheimer's disease patients and healthy individuals. In addition, the influence of overnight fasting on ABeta42 in plasma from healthy individuals was examined.
Summary of Findings:
Four sequential collections of CSF from the same individual did not significantly differ in ABeta42 concentration. However, a small but significant decrease in CSF ABeta42 concentration was observed in specimens collected 4-6 hours after baseline values were obtained (-9.3%, p<0.001), but a subsequent tendency of values to return to baseline was observed in specimens collected 24 h after baseline values were obtained (-4.4%, p<0.002). Overnight fasting had no effects on plasma ABeta42 concentrations compared to specimens taken after breakfast was eaten. Deliberate contamination of CSF with blood (200-5000 erythrocytes/uL) had no effects on ABeta42 concentration compared to uncontaminated CSF, but dilution of CSF with serum albumin from added plasma resulted in significantly decreased ABeta42 concentrations compared to undiluted CSF.
Biospecimens
Preservative Types
- Frozen
Diagnoses:
- Alzheimer's Disease
- Normal
Platform:
Analyte Technology Platform Protein ELISA Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Biospecimen Aliquots and Components Biospecimen components CSF plus 200 erythrocytes/uL
CSF plus 1000 erythrocytes/uL
CSF plus 5000 erythrocytes/uL
CSF plus water
CSF with 0.20 g/L serum albumin
CSF with 0.25 g/L serum albumin
CSF with 0.50 g/L serum albumin
CSF with 1.0 g/L serum albumin
CSF with 2.0 g/L serum albumin
Preaquisition Patient diet Nonstandardized breakfast
Overnight fasting
Biospecimen Aliquots and Components Aliquot sequential collection 1st collection
2nd collection
3rd collection
4th collection
Biospecimen Acquisition Time of biospecimen collection Baseline
4-6 h later
24 h later
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Study Purpose
The purpose of this study was to determine the effects of time at room temperature on the pH of CSF, as well as to determine the effects of the type, concentration, and pH of dilution buffer, and the addition of detergent on the measurement of ABeta42 in CSF from Alzheimer's patients and normal individuals.
Summary of Findings:
The use of PBS, HEPES or Tris buffer rather than the manufacturer provided assay buffer did not affect ABeta42 levels. Further, different concentrations of PBS, and different pH values of Tris buffer had no effects on measured ABeta42 levels in CSF. The authors report that the addition of BSA, Triton100, or Tween20 equally improved the ABeta42 signal. CSF pH increased significantly when specimens were stored at room temperature over the course of 5 hours (from 7.9 to 8.7) compared to starting measurements taken within 30 min of collection.
Biospecimens
Preservative Types
- None (Fresh)
Diagnoses:
- Alzheimer's Disease
- Normal
Platform:
Analyte Technology Platform Small molecule Clinical chemistry/auto analyzer Protein ELISA Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Storage Time at room temperature Less than 30 min
Up to 5 hours
Biospecimen Preservation Fixative additive/buffer HEPES
Phosphate buffered saline (PBS)
Tris buffer
Multiple concentrations evaluated
BSA
Triton100
Tween20
Biospecimen Aliquots and Components pH 7.4
8
9