Molecular insight into thiopurine resistance: transcriptomic signature in lymphoblastoid cell lines.

Background: There has been considerable progress in the management of acute lymphoblastic leukemia (ALL) but further improvement is needed to increase long-term survival. The thiopurine agent 6-mercaptopurine (6-MP) used for ALL maintenance therapy has a key influence on clinical outcomes and relapse prevention. Genetic inheritance in thiopurine metabolism plays a major role in interindividual clinical response variability to thiopurines; however, most cases of thiopurine resistance remain unexplained.

Optimization and validation of a label-free MRM method for the quantification of cytochrome P450 isoforms in biological samples.

Cytochromes P450 (CYPs) play critical roles in oxidative metabolism of many endogenous and exogenous compounds. Protein expression levels of CYPs in liver provide relevant information for a better understanding of the importance of CYPs in pharmacology and toxicology. This work aimed at establishing a simple method to quantify six CYPs (CYP3A4, CYP3A5, CYP1A2, CYP2D6, CYP2C9, and CYP2J2) in various biological samples without isotopic labeling.

Melatonin protects PLPC liposomes and LDL towards radical-induced oxidation.

This study investigated the in vitro protective effects of melatonin against oxidation of 1-palmitoyl-2-linoleoyl-sn-glycero-3-phosphocholine (PLPC) liposomes [(PLPC) = 250 μm] and low-density lipoproteins (LDL, 3 g/L total concentration) by hydroxyl radicals produced by water gamma radiolysis. Conjugated dienes (CD) and hydroperoxides from cholesteryl esters (CEOOH) and phospholipids (PCOOH) were measured as indices of lipid peroxidation. Protein (apoB) oxidation in LDL was assessed by carbonyl groups.

Interaction between non-anionic phospholipids and cytochrome c induced by reactive oxygen species.

The oxidative interaction of cytochrome c (Cyt c) with liposomes of Palmitoyl Linoleyl Phosphatidyl Choline (PLPC) initiated by radio-induced free radicals was investigated. Results showed that the peroxidation of PLPC is decreased in the presence of Cyt c, meaning that this latter is the preferential target of hydroxyl radicals. In addition, when Cyt c was incubated with peroxidized PLPC, it was found to be able to decompose hydroperoxides of PLPC into hydroxides.

Liquid chromatographic/electrospray ionization mass spectrometric identification of the oxidation end-products of trans-resveratrol in aqueous solutions.

trans-Resveratrol (3,5,4'-trihydroxystilbene) is a natural polyphenolic compound that exhibits antioxidant properties. Our study aimed at studying the HO*-induced oxidation of resveratrol (100 micromol.L(-1)) in aerated aqueous solutions.

Online H/D exchange liquid chromatography as a support for the mass spectrometric identification of the oxidation products of melatonin.

The hydrogen-deuterium exchange of protonated melatonin and its in vitro oxidation end-products have been examined by liquid chromatography coupled with ion-trap mass spectrometry. Specific H/D scrambling of protons in the C2 and C4 positions of the indole ring during gas-phase fragmentation process was observed for both melatonin and its oxidation products. Collision-induced dissociation spectra showed losses of variably deuterated NH(3), H(2)O and CH(3)CONH(2).

Marked difference in cytochrome c oxidation mediated by HO(*) and/or O(2)(*-) free radicals in vitro.

Cytochrome c (cyt c) is an electron carrier involved in the mitochondrial respiratory chain and a critical protein in apoptosis. The oxidation of cytochrome c can therefore be relevant biologically. We studied whether cytochrome c underwent the attack of reactive oxygen species (ROS) during ionizing irradiation-induced oxidative stress.