Measurement of neosaxitoxin in human plasma using liquid-chromatography tandem mass spectrometry: Proof of concept for a pharmacokinetic application.

Neosaxitoxin, a member of the saxitoxin family of paralytic shellfish poisoning toxins, has shown potential as an effective, long-acting, anesthetic. We describe the development and validation of a highly sensitive method for measurement of neosaxitoxin in human plasma using liquid chromatography tandem mass spectrometry (LC-MS/MS) and provide evidence for its use in a human pharmacokinetic study. Samples were prepared using cation exchange solid phase extraction followed by hydrophilic interaction liquid chromatography and MS/MS detection in positive electrospray ionization mode.

Improved separation and analysis of plasma amino acids by modification of the MassTrak™ AAA Solution Ultraperformance® liquid chromatography method.

Background: Ultraperformance® Liquid Chromatography (UPLC) is increasingly used for quantitative amino acid screening. The Waters MassTrak™ UPLC Amino Acid Analysis (AAA) Solution kit offers rapid analysis with minimal sample preparation. We describe a simple modification of this method enabling enhanced chromatographic separation of previously problematic analytes with improvements in quantification.

Variation in clinical vitamin D status by DiaSorin Liaison and LC-MS/MS in the presence of elevated 25-OH vitamin D2.

Background: We compared total 25-OH vitamin D status measured by DiaSorin Liaison and tandem mass spectrometry (LC-MS/MS) among patients with high and low 25-OH vitamin D(2).

Methods: Total 25-OH vitamin D was measured in plasma containing high (>25 nmol/l or >50%, n=26) and low (<2.5 nmol/l, n=29) 25-OH vitamin D(2) using DiaSorin Liaison and an LC-MS/MS method using NIST 972-verified calibrators.

Acute effects of ingestion of a novel whey-derived extract on vascular endothelial function in overweight, middle-aged men and women.

Whey protein intake reduces CVD risk, but little is known whether whey-derived bioactive peptides regulate vascular endothelial function (VEF). We determined the impact of a whey-derived extract (NOP-47) on VEF in individuals with an increased cardiovascular risk profile. Men and women with impaired brachial artery flow-mediated dilation (FMD) (n 21, age 55 (sem 1·3) years, BMI 27·8 (sem 0·6) kg/m2, FMD 3·7 (sem 0·4) %) completed a randomised, cross-over study to examine whether ingestion of NOP-47 (5 g) improves postprandial VEF.

A multiplex immunoassay gives different results than singleplex immunoassays which may bias epidemiologic associations.

Objectives: Multiplex immunoassays are increasingly used in epidemiologic studies to measure inflammatory factors, however there are few published evaluations of this technology. Our objective was to compare a common multiplex immunoassay to singleplex immunoassays for measuring inflammatory factors, and to examine how combining data from each affects an epidemiologic association.

Design And Methods: Plasma IL-1 beta, IFN-gamma, IL-6, and TNF-alpha were measured in 100 samples using a multiplex kit from Mesoscale Discovery (MSD) and singleplex ELISAs from R&D Systems.