Effect of Sample Collection Tubes on Cerebrospinal Fluid Concentrations of Tau Proteins and Amyloid β Peptides

Abstract

the oral administration of metallic colloids, in particular colloidal silver protein, has been reported to have toxic effects (2 ). Despite this, dozens of companies sell metal colloids as nutritional supplements.Many metal colloids have been rebranded as "nano" compounds to further intensify the public's interest in their utility. Although clinical concern about the use of colloidal metallic compounds is longstanding, their effects on laboratory tests have not been investigated. These particles are of particular concern because their small size allows high oral bioavailability, accumulation within the blood, and excretion through the kidneys (5 ). We were interested to know whether metal colloids might cause interference in clinical chemistry tests of blood and urine.We tested 4 nutraceutical products: Mesogold, Mesosilver, Mesocopper, and Mesoplatinum [Purest Colloids, Inc.; daily recommended doses ranged from 50 to 150 g (4 )]. These were colloidal suspensions of nonionic metal with 1-to 10-nm diameter particles. The concentrations of copper, silver, platinum, and gold measured by National Medical Services, Inc. were 0.9, 21, 13, and 18 mg/L of each metal, respectively, whereas the manufacturer's stated concentrations were 10, 20, 10, and 10 mg/L, respectively.We tested the mesometals (undiluted and as 1:1 mixtures with saline or pooled serum) for interference in a range of automated assays on a Vitros ® Model 950 AT:

Cerebrospinal Fluid Collection Tubes: A Critical Issue for Alzheimer Disease Diagnosis

“…Although polypropylene (PP) was previously reported as the best material for CSF collection tubes (2 ), heterogeneity in CSF A␤1-42 values was observed with different PP sampling tubes (3 ). Because the recommendation to use PP tubes did not lead to standardization of clinical cutoff values (4 ), we decided to fully address this issue by comparing various types of tubes within an actual clinical work flow and by analyzing the material of different commercially available PP tubes.…”

Cerebrospinal Fluid Biomarkers for Huntington’s Disease

“…Polystyrene and polyethylene tubes have been shown to artefactually diminish CSF levels of amyloid beta compared with polypropylene tubes, through adsorption of the protein to the plastic surface [77]. Similar effects may well be seen with any other protein; most have not been investigated for such technical effects.…”

Quantitative detection of amyloid-β peptides by mass spectrometry: state of the art and clinical applications

“…Composition of tubes used to collect CSF during lumbar puncture has a strong influence on Aβ peptide concentrations [32]. This is in relation with the tendency of Aβ peptides to adsorb to the walls of the tube.…”

“…Hence, it has been shown that glass and polystyrene tubes led to lower measured concentrations of Aβ peptides [25,31]. Polypropylene tubes were believed to reduce this phenomenon [32]. However, even polypropylene tubes which are not made entirely of polypropylene, and have various surface treatments, have a major impact on Aβ peptide measured concentrations [25].…”