PubMed · 7370548
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R J Ratcliffe, P L Willan. 1980-02-16. Intermittent venous sampling during exercise.. https://doi.org/10.1136/bmj.280.6212.483-b
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Home collection kits allow individuals to obtain a blood specimen at home and send it to a laboratory for HIV testing. In preliminary studies, 15% of kit users submitted specimens considered to be insufficient for analysis. The current Public Health Service policy requires the laboratory to reject all such specimens entirely and request a second specimen, even though some specimens are sufficient to perform an enzyme immunoassay (EIA) but not a Western blot (WB) test. Using decision analysis, we evaluated three strategies to handle specimens sufficient to perform an EIA but insufficient to perform a WB analysis: current recommendation, or baseline, for which no test is preformed and "quantity not sufficient" is reported; alternative 1 , for which an EIA is done and reported as "negative" or "quantity not sufficient" (if initially reactive); and alternative 2, for which an EIA is done and reported as "negative" or "a reactive screening test" (if initially reactive). Baseline strategy requires all consumers with an initial specimen sufficient for EIA only to submit a second specimen, but either alternative requires fewer than 3% to submit a second specimen. Although 80% of consumers with an initial specimen sufficient for EIA learn their test results only with the baseline strategy, more than 99% learn their test results with either alternative. With the scenario of high (2%) HIV prevalence, 91% of consumers who would be told "reactive screening test" are truly infected. At a low (0.1%) HIV prevalence, 33% of consumers who would be told "reactive screening test" are truly infected. When a specimen is sufficient for EIA only, it is preferable to perform the EIA instead of rejecting the specimen, because many persons can get results from the initial specimen and because many fewer are required to submit a second specimen. Current policy should be reexamined in light of these findings.
Human serum albumin (HSA) in fresh frozen and freeze-dried serum reference materials was examined by mass spectrometry and a variety of affinity chromatography techniques. The relative molecular mass distribution of HSA in fresh frozen serum was found to be identical to that of an HSA standard. However, the HSA in the freeze-dried reference serum exhibited a relative molecular mass distribution that was shifted to higher mass, broader, and substantially more heterogeneous than that of HSA in fresh frozen serum. A proteolytic cyanogen bromide digestion of the HSA from freeze-dried serum contained adducts approximately 162 u higher in mass than digest fragments 124-298 and 447-548, suggesting glycation. The presence of glycation on fragments 124-298 and 447-548 correlates with the known sites of HSA glycation. Glycation was further confirmed by the mass spectral analysis of the retained and unretained fractions from glycoaffinity chromatography of HSA from freeze-dried serum. The relative molecular weight of the HSA in the retained fraction indicated the presence of a doubly glycated species. The chemical heterogeneity of Cys-34, the site of the only free thiol in HSA, was examined and found not to be a substantial source of molecular mass heterogeneity for HSA from either fresh frozen of freeze-dried serum.