One possible factor determining recovery of trace amount of protein biomarker
candidates during proteome analyses could be adsorption on urine tubes. This
issue, however, has not been well addressed so far. Recently, a new technical
device of surface coating by poly(2-methacryloyloxyethyl phosphorylcholine
(MPC)-co-n-butyl methacrylate (BMA))
(poly(MPC-co-BMA)) has been developed mainly to prevent the
adsorption of plasma proteins. We assessed whether conventionally used urine
tubes adsorb trace amount of urinary proteins and, if any, whether the surface
coating by poly(MPC-co-BMA) can minimize the adsorption.
Proteinuric urine samples were kept in poly(MPC-co-BMA)-coated
and noncoated urine tubes for 15 min and possibly adsorbed proteins and/or
peptides onto urine tubes were analyzed by SDS-PAGE, 2-DE, and the MALDI-TOF MS.
It was found that a number of proteins and/or peptides adsorb on the
conventionally used urine tubes and that surface coating by
poly(MPC-co-BMA) can minimize the adsorption without any
significant effects on routine urinalysis test results. Although it remains to
be clarified to what extent the protein adsorption can modify the results of
urinary proteome analyses, one has to consider this possible adsorption of
urinary proteins when searching for trace amounts of protein biomarkers in
urine.
SummarySince there is wide interobserver variabilities in microscopic urinary sediment evaluation, quality control programs for urinary sediment test using control materials are warranted in Japan. We performed internal quality control using home-brew control materials and cross-checking of urinary sediment tests by the three technologists including two experts and one newcomer. Variabilities among the three technologists in counting red blood cell RBC , white blood cell WBC , and casts were found to be improved as early as five days after the start of quality control particularly in the newcomer. Half a year later, coefficients of variation of the three technologists in counting these components were all about ten percent, which were lower than those observed in the initial examination.In the cross-checking of urinary sediments, more than 93% of the results of RBC and WBC and 84% of the results casts were reported within one lank difference. The rare components including waxy cast, atypical cell, dysmorphic RBC, Trichomonas vaginalis were detected similarly by the three technologists. Thus, internal quality control of urinary sediment tests using home-brew control materials and cross-checking among medical technologists is useful for standardization of urinary sediment tests and training of a newcomer in a clinical laboratory.48 48
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