A simple and rapid ultra-high-performance liquid chromatography-tandem mass spectrometry method to determine plasma biotin in hemodialysis patients.
A simple, rapid, and selective method for determination of plasma biotin was developed using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). After single-step protein precipitation with methanol, biotin and stable isotope-labeled biotin as an internal standard (IS) were chromatographed on a pentafluorophenyl stationary-phase column (2.1 × 100 mm, 2.7 μm) under isocratic conditions using 10 mm ammonium formate-acetonitrile (93:7, v/v) at a flow rate of 0.6 mL/min. The total chromatographic runtime was 5 min for each injection. Detection was performed in a positive electrospray ionization mode by monitoring selected ion transitions at m/z 245.1/227.0 and 249.1/231.0 for biotin and the IS, respectively. The calibration curve was linear in the range of 0.05-2 ng/mL using 300 μL of plasma. The intra- and inter-day precisions were all <7.1%. The accuracy varied from -0.7 to 8.2%. The developed UHPLC-MS/MS method was successfully applied to determine plasma biotin concentrations in hemodialysis patients. Copyright © 2016 John Wiley & Sons, Ltd.
Methods for assessment of biotin (Vitamin B7)
Abstract Biotin (vitamin B7, hexahydro-2-oxo-1H-thieno[3,4-d]imidazole-4-pentanoic acid) is not synthesized by mammals: dietary sources include plant based foods, yeast, liver, kidneys, heart, pancreas, egg yolk, poultry, and cow’s milk. Synthesis via the gut bacteria may also play a role. Recommended daily allowances are based on normal intake; EU RDA is 50 μg/day, the US adequate intake (AI) for adults is 30 μg/day.Biotin is required for the function of four carboxylases: pyruvate carboxylase, propionyl CoA carboxylase, multiple CoA carboxylase, and acetylCoA carboxylase I and II. Holocarboxylase synthase is required to attach biotin to their active sites. Biotin also modulates the expression of up to 2000 genes, and has effects on immune function, largely through biotinylation of histones and other proteins.Biotinidase, the enzyme which splits biotin from biotinyl lysine (biocytin), and from peptides containing biocytin, recycles biotin from endogenous turnover and facilitates absorption from exogenous sources, together with the sodium-dependent multivitamin transporter.Nutritional deficiency of biotin is rare and most cases relate to inborn errors of biotin metabolism and transport, long-term use of parenteral nutrition, chronic anticonvulsant therapy, or avidin binding of dietary biotin due to excessive ingestion of egg whites.Excessive ingestion of biotin from supplements is increasingly common. Biotin has no direct toxicity, but high circulating levels can interfere with many commercially available immunoassays which use the interaction between biotin and streptavidin. This can result in a spurious but plausible biochemical picture of disease supported by two or more independent immunoassay based tests.The laboratory detection of functional biotin deficiency relies upon detection of multiple carboxylase deficiency, identified and followed by measurement of urinary 3-hydroxyisovaleric acid (3HIVA, ideally using isotope dilution GC-MS, or isotope dilution-LC-MSMS (ID-LC-MSMS)) or plasma 3-hydroxyisovaleryl carnitine (3HIVc, measured using ID-LC-MSMS). These methods are reviewed, together with methods for assessing biotinidase activity.This chapter also describes methods for the direct measurement of biotin in foods, blood, serum/plasma, and urine. These relied for many years on microbiological assays. These were followed by binding assays using avidin with radioactive biotin or enzyme linked biotin as tracers, with or without chromatographic separation to distinguish between biotin, metabolites of biotin, and biotinylated peptides. Latterly, the introduction of specific assays using ID-LC-MSMS should allow traceable and harmonized assay of plasma/serum biotin. These could be particularly helpful to detect excessive ingestion of biotin supplements.We conclude that there is a need for laboratory methods with adequate sensitivity and specificity to reliably diagnose biotin deficiency and monitor biotin levels in patients receiving supplements. There are a limited number of reliable markers of biotin status and no single marker can reliably distinguish moderately deficient biotin from sufficient and supplemented. Measurement of 3HIVA and 3HIVc, the functional markers of biotin status, is currently the recommended approach.
Do Potential People Have Moral Rights?
By a potential person I shall mean an entity which is not now a person but which is capable of developing into a person, given certain biologically and/or technologically possible conditions. This is admittedly a narrower sense than some would attach to the term ‘potential'. After all, people of the twenty-fifth century, if such there will be, are in some sense potential people now, even though the specific biological entities from which they will develop, i.e. the particular gametes or concepti, do not yet exist. For there do exist, in the reproductive capacities of people now living and in the earth's resources, conditions adequate to produce these future people eventually, provided of course that various possible catastrophes are avoided. Indeed, in some sense of ‘potential’ there have been countless billions of potential people from the beginning of time. But I am concerned not with such remote potentialities but with currently existing entities that are capable of developing into people.