PubMed · 5902696
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
H Kopelman, M H Robertson, P G Sanders, I Ash. 1966-02-26. The Epping jaundice.. https://doi.org/10.1136/bmj.1.5486.514
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
A high-throughput assay for UDP-Glc:(1,3)-beta-glucan synthase(EC 2.4.1.34, UDP-glucose:1,3-beta-D-glucan, 3-beta-glucosyltransferase) from fungi and higher plants is described. The assay is performed in microtiter plates and is extremely inexpensive compared to other standard assays for these enzymes. The reduction in price is achieved by replacing the conventional substrate UDP-[14C]Glc with its nonradioactive counterpart, and the nonradioactive glucan produced is quantified as a fluorescent complex following specific interaction with the fluorochrome present in commercial aniline blue. In addition to a > 100-fold reduction in cost, the assay is highly reproducible and nearly as sensitive as radioactive assays and has the additional advantages of increased safety and avoidance of the need for filtration and washing steps to collect the glucan product. As such, the assay is highly suitable for high-throughput screening for inhibitors of these enzymes.
Oxidant-induced damage has been proposed to be the underlying mechanism for loss of membrane phospholipid asymmetry in the erythrocyte membrane. In sickle cell disease, thalassemia, and diabetes as well as in senescent erythrocytes, an apparent correlation between oxidative damage and loss of phosphatidylserine asymmetry has been reported. In the present study, erythrocytes were subjected to various levels of oxidative stress and/or sulfhydryl modifying agents. The transmembrane location of phosphatidylserine (PS) was assessed by FITC-conjugated annexin V labeling and the PS-dependent prothrombinase assay. Transbilayer movement of spin-labeled PS was used to determine aminophospholipid translocase activity. Our data show that cells did not expose PS as the result of oxidative stress induced by phenylhydrazine, hydrogen peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, or sulfhydryl modification by N-ethylmaleimide (NEM) and diamide, even under conditions that led to severe cellular damage and impairment of aminophospholipid translocase activity. In contrast, the increase of intracellular calcium induced by treatment with calcium and ionophore A23187 leads to a rapid scrambling of the lipid bilayer and the exposure of PS, which can be exacerbated by the inhibition of aminophospholipid translocase activity. Oxidation of the cells with hydrogen peroxide or phenylhydrazine did not affect A23187-induced uptake of calcium, but partly inhibited calcium-induced membrane scrambling. In conclusion, oxidative damage of erythrocytes does not induce exposure of phosphatidylserine on the membrane surface, but can interfere with both aminophospholipid translocase activity and calcium-induced randomization of membrane phospholipids.
Explore the source record for details and available documents.