An LC-MS/MS based candidate reference method for the quantification of total gentamicin in human serum and plasma using NMR characterized calibrator material.

Background: Accurate measurement of gentamicin concentration in serum and plasma is required for therapeutic drug monitoring to ensure appropriate treatment of patients. In this work, we present a validated LC-MS/MS-based candidate reference measurement procedure for total gentamicin quantification to be used for standardization and harmonization of routine assays applied for therapeutic drug monitoring of this compound. Total gentamicin is the sum of the concentrations of five known congeners C1, C1a, C2, C2a and C2b.

Release of anandamide from blood cells.

Background: Endogenous ligands of cannabinoid receptors (endocannabinoids), in particular anandamide (arachidonylethanolamide), have been recognized as being of crucial importance in a variety of physiological functions. Plasma concentrations of anandamide have been measured in a number of investigations; however, discrepant data on "normal" anandamide plasma concentrations were reported. Since this might be caused by pre-analytical variables, we investigated the impact of different sample handling conditions on measured plasma anandamide concentrations.

Binding analysis of 1alpha- and 17alpha-dihydrotestosterone derivatives to homodimeric sex hormone-binding globulin.

Binding studies of the interaction of immobilized 1alpha- and 17alpha-aminoalkyl derivatives of 5alpha-dihydrotestosterone (DHT) with purified N-deglycosylated homodimeric human sex hormone-binding globulin (SHBG) were performed using a surface plasmon resonance biosensor. These 1alpha- and 17alpha-derivatives with spacers of appropriate lengths between the amine function and the steroid ring skeleton enabled privileged, sterically undisturbed, interactions of either the 17- or 3-characteristic functional groups of DHT with SHBG. The association constants (K(a)1) for the binding of these immobilized DHT derivatives to the first binding site of SHBG, determined by SPR measurements, were 0.