Liquid Chromatography-tandem Mass Spectrometry Quantification Research Articles

Retrospective Diagnosis of an Adverse Drug Reaction in a Breastfed Neonate: Liquid Chromatography-Tandem Mass Spectrometry Quantification of Dextropropoxyphene and Norpropoxyphene in Newborn and Maternal Hair

Dextropropoxyphene (DP) and norpropoxyphene (NP) are commonly used in the treatment of postpartum pain. The drug is widely prescribed in Europe and Canada and has been recently approved for use in the U.S. Its safety during breastfeeding, however, has not been fully established. Very few reports on its effects on neonates have been published. We report here the case of a mother treated with DP (6 capsules a day for 10 days) while she was breastfeeding. On day 7, her baby was lethargic and had difficulties with breastfeeding, which led to early weaning. The correlation between side effects observed in the infant and DP was made retrospectively by measuring DP and NP hair concentrations in the mother-infant pair with liquid chromatography-tandem mass spectrometry. Breastfeeding mothers taking DP expose their infants to high doses of DP and NP. In agreement with previously published reports, these data indicate that acetaminophen and nonsteroidal antiinflammatories are preferable for analgesia during breastfeeding. Breastfeeding should be encouraged under most circumstances, and if the mother takes any treatment for pain, a commonly prescribed drug with pharmacologic data available must be used.

Absolute Difference of Hepatobiliary Transporter Multidrug Resistance-Associated Protein (MRP2/Mrp2) in Liver Tissues and Isolated Hepatocytes from Rat, Dog, Monkey, and Human

We previously reported that hepatobiliary transporter multidrug resistance-associated protein (MRP2/Mrp2) is considered to be the major cause of the interspecies differences detected by efflux of fluorescent substrates in isolated hepatocytes. In the present study, the interspecies differences of MRP2/Mrp2 were first evaluated by quantitative real-time polymerase chain reaction and Western blotting. The mRNA levels were able to distinguish the difference among species with a rank order comparable with the corresponding activities observed, whereas the extents of the differences remained unknown. The cross-reactions of MRP2/Mrp2 protein of different species with anti-human MRP2 polyclonal antibody were found by Western blotting. However, because of the unknown binding affinity of antibody to MRP2/Mrp2 protein across species and lack of purified MRP2/Mrp2 proteins for calibration, the immunoblotting assay was excluded from the absolute quantification of MRP2/Mrp2 protein for multiple species. By using our newly developed liquid chromatography-tandem mass spectrometry quantification method, we were able to measure the absolute amount of MRP2/Mrp2 in liver tissues and isolated hepatocytes across species. Freshly isolated hepatocytes conserved MRP2/Mrp2 protein levels that are comparable with those in the liver tissues. The amount of Mrp2 in rat liver was approximately 10-fold higher than that in other species. Moreover, a significant loss of Mrp2 protein in the membrane fraction of rat cryopreserved hepatocytes was observed. Thus, the absolute differences of MRP2/Mrp2 levels in various species were determined, for the first time, by direct quantification. The results could potentially fill the translational gaps of in vitro/in vivo or preclinical species to human extrapolation of hepatobiliary elimination mediated by MRP2/Mrp2.

Liquid Chromatography–Tandem Mass Spectrometry Quantification of Globotriaosylceramide in Plasma for Long-Term Monitoring of Fabry Patients Treated with Enzyme Replacement Therapy

Fabry disease is a rare X-linked lysosomal storage disorder resulting from a deficiency in the α-galactosidase A enzyme. Deficiency in the activity of this enzyme causes an accumulation of neutral glycosphingolipids, predominantly globotriaosylceramide (GL-3), in most nonneural tissues and in body fluids (1). Recent clinical studies indicate that tissue and plasma GL-3 concentrations in Fabry patients can be significantly reduced by enzyme replacement therapy (2)(3)(4)(5). GL-3 (see Fig. 1 in the Data Supplement that accompanies the online version of this Technical Brief at http://www.clinchem.org/content/vol51/issue1/) exists as a mixture of structural isoforms containing acyl chains ranging from 16 to 24 carbons in length with various degrees of saturation and hydroxylation. These variations make the extraction and quantification of GL-3 challenging (6)(7). Moreover, no well-characterized reference standards of known purity are available. GL-3 in tissues and plasma has been measured by thin-layer chromatography (8)(9), liquid chromatography (LC) (10)(11)(12)(13)(14)(15), and gas chromatography(16), but the methods are labor-intensive and slow. An enzyme-linked immunosorbent assay (17) requires recombinant verotoxin B and polyclonal rabbit anti-verotoxin B. To date, the most rapid quantitative assays for total GL-3 have used flow-injection tandem mass spectrometry (MS/MS) (18)(19). We now report the development and use of a rapid LC/MS/MS method for the quantitative determination of total plasma GL-3. Porcine GL-3 and porcine globotriaosylsphingosine A ( lyso -GL-3), from Matreya, were ≥98% pure by thin-layer chromatographic analysis. C16:0-GL-3 and C17:0-GL-3 were enzymatically synthesized from lyso -GL-3 at Genzyme Pharmaceuticals (18). C16:0-enriched GL-3 was prepared by gravimetrically combining C16:0-GL-3 and porcine GL-3 in a 9:25 g/g mass ratio. Methanol, water, and chloroform were HPLC grade. Normal heparin-plasma samples from 104 men and 101 women were obtained from Interstate Blood …

O-18-261 - Surgery of central region epilepsy

Dried blood spot (DBS) sampling has gained attention in several scientific areas because of the low sampling burden. The study aimed to develop a method for the determination of poly- and perfluoroalkyl substances (PFASs) in DBS using a standardized blood volume. The DBS method using a simple methanol extraction followed by online solid phase extraction-ultra high performance liquid chromatography-tandem mass spectrometry quantification was validated. Only 30 μL of blood is required. Based on the measurements of DBS dispersed areas from known blood volumes (20–70 μL), the blood volume on a 3 mm diameter DBS subsample was calculated to be 3.3 μL (median, n = 708 measurements, 59 adults). Strong correlations of PFAS concentrations between finger prick DBSs and venous whole blood samples (n = 57) were found (rho 0.72–0.97, p < 0.0001). Also, Passing-Bablok regressions and Bland-Altman plots demonstrated good agreements of PFAS concentrations in finger prick DBSs and venous whole blood samples. This finding indicates that the DBS method was satisfactory, and allows straightforward analysis of PFASs in DBS without hematocrit correction. This DBS method is reliable for accurate determination of PFASs and has a high potential for use of self-collected DBS in large-scale biomonitoring studies as well as for archived DBS samples.