PubMed · 633641
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T Usui. 1978. [Fluorometric analysis (author's transl)].. https://pubmed.ncbi.nlm.nih.gov/633641/
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A rapid and sensitive method for the determination of naproxen and salicylate in serum is presented. The employed strategy combines solid-phase extraction on a reverse-phase membrane with spectrofluorimetry. Solid-phase extraction under optimum pH conditions makes NX to be retained over the solid surface (where it is directly determined by a fluorimetric technique). Salicylate passes through the disk and is also fluorimetrically determined, but in solution. The linear calibration ranges for NX in the membrane and salicylate in solution were 0.014-0.250 and 0.010-0.250 microg ml(-1), respectively. The lowest value, in each case, is the corresponding limit of quantitation. The performance of the method is demonstrated with the successful determination of both drugs in spiked and real human serum samples.
Green fluorescent protein (GFP) has become an increasingly popular protein tag for determining protein localization and abundance. With the availability of GFP variants with altered fluorescence spectra, as well as GFP homologues from other organisms, multi-colour fluorescence with protein tags is now possible, as is measuring protein interactions using fluorescence resonance energy transfer (FRET). We have created a set of yeast tagging vectors containing codon-optimized variants of GFP, CFP (cyan), YFP (yellow), and Sapphire (a UV-excitable GFP). These codon-optimized tags are twice as detectable as unoptimized tags. We have also created a tagging vector containing the monomeric DsRed construct tdimer2, which is up to 15-fold more detectable than tags currently in use. These tags significantly improve the detection limits for live-cell fluorescence imaging in yeast, and provide sufficient distinguishable fluorophores for four-colour imaging.
Here we have studied how the length of the pyrene-labeled acyl chain (n) of a phosphatidylcholine, sphingomyelin, or galactosylceramide affects the partitioning of these lipids between 1), gel and fluid domains coexisting in bovine brain sphingomyelin (BB-SM) or BB-SM/spin-labeled phosphatidylcholine (PC) bilayers or 2), between liquid-disordered and liquid-ordered domains in BB-SM/spin-labeled PC/cholesterol bilayers. The partitioning behavior was deduced either from modeling of pyrene excimer/monomer ratio versus temperature plots, or from quenching of the pyrene monomer fluorescence by spin-labeled PC. New methods were developed to model excimer formation and pyrene lipid quenching in segregated bilayers. The main result is that partition to either gel or liquid-ordered domains increased significantly with increasing length of the labeled acyl chain, probably because the pyrene moiety attached to a long chain perturbs these ordered domains less. Differences in partitioning were also observed between phosphatidylcholine, sphingomyelin, and galactosylceramide, thus indicating that the lipid backbone and headgroup-specific properties are not severely masked by the pyrene moiety. We conclude that pyrene-labeled lipids could be valuable tools when monitoring domain formation in model and biological membranes as well as when assessing the role of membrane domains in lipid trafficking and sorting.