Metabolite profiling of guanfacine in plasma and urine of healthy Japanese subjects after oral administration of guanfacine extended-release tablets.

Guanfacine is used for the treatment of attention-deficit/hyperactivity disorder (ADHD). Using liquid chromatography-tandem mass spectrometry (LC-MS/MS), metabolite profiling of guanfacine was performed in plasma and urine collected from healthy Japanese adults following repeated oral administration of guanfacine extended-release formulation. Unchanged guanfacine was the most abundant component in both plasma and urine (from the MS signal intensity).

Bioanalytical Method for the Determination of Hydroxyproline in Mouse Kidney by High-Performance Liquid Chromatography with Tandem Mass Spectrometric Detection.

An analytical method was developed and validated for the measurement of hydroxyproline (Hyp) levels in mouse kidney by high-performance liquid chromatography with tandem mass spectrometric detection (LC/MS/MS) using an analytical column specially designed for the LC/MS/MS analysis for intact amino acids. Tissue hydrolyzed with hydrochloric acid could be directly injected into the LC/MS/MS, as well as separated and detected using the deuterium labelled Hyp as an internal standard. The calibration curve showed good linearity from 5 to 500 nmol/mg of tissue; the precision and accuracy, including within- and between-run, were less than 6% and within 100 ± 6%, respectively.

Possible roles of long-chain sphingomyelines and sphingomyelin synthase 2 in mouse macrophage inflammatory response.

To evaluate the precise role of sphingomyelin synthase 2 (SMS2) in sphingomyelin (SM) metabolism and their anti-inflammatory properties, we analyzed species of major SM and ceramide (Cer) (18:1, 18:0 sphingoid backbone, C14 - C26 N-acyl part) in SMS2 knockout and wild-type mouse plasma and liver using HPLC-MS. SMS2 deficiency significantly decreased very long chain SM (SM (d18:1/22:0) and SM (d18:1/24:0 or d18:0/24:1)) and increased very long chain Cer (Cer (d18:1/24:0 or d18:0/24:1) and Cer (d18:1/24:1)), but not long chain SM (SM (d18:1/16:0), SM (d18:1/18:0 or d18:0/18:1) and SM (d18:1/18:1)) in plasma. To examine the effects of SM on inflammation, we studied the role of very long chain SM in macrophage activation.

Identification of a new endogenous metabolite and the characterization of its protein interactions through an immobilization approach.

The emerging field of global mass-based metabolomics provides a platform for discovering unknown metabolites and their specific biochemical pathways. We report the identification of a new endogenous metabolite, N(4)-(N-acetylaminopropyl)spermidine and the use of a novel proteomics based method for the investigation of its protein interaction using metabolite immobilization on agarose beads. The metabolite was isolated from the organism Pyrococcus furiosus, and structurally characterized through an iterative process of synthesizing candidate molecules and comparative analysis using accurate mass LC-MS/MS.

Correlating the transcriptome, proteome, and metabolome in the environmental adaptation of a hyperthermophile.

We have performed a comprehensive characterization of global molecular changes for a model organism Pyrococcus furiosus using transcriptomic (DNA microarray), proteomic, and metabolomic analysis as it undergoes a cold adaptation response from its optimal 95 to 72 degrees C. Metabolic profiling on the same set of samples shows the down-regulation of many metabolites. However, some metabolites are found to be strongly up-regulated.

From exogenous to endogenous: the inevitable imprint of mass spectrometry in metabolomics.

Mass spectrometry (MS) is an established technology in drug metabolite analysis and is now expanding into endogenous metabolite research. Its utility derives from its wide dynamic range, reproducible quantitative analysis, and the ability to analyze biofluids with extreme molecular complexity. The aims of developing mass spectrometry for metabolomics range from understanding basic biochemistry to biomarker discovery and the structural characterization of physiologically important metabolites.

Mass spectrometry reveals specific and global molecular transformations during viral infection.

Mass spectrometry analysis was used to target three different aspects of the viral infection process: the expression kinetics of viral proteins, changes in the expression levels of cellular proteins, and the changes in cellular metabolites in response to viral infection. The combination of these methods represents a new, more comprehensive approach to the study of viral infection revealing the complexity of these events within the infected cell. The proteins associated with measles virus (MV) infection of human HeLa cells were measured using a label-free approach.

Electrogenerated chemiluminescence derivatization reagent, 3-isobutyl-9,10-dimethoxy-1,3,4,6,7,11b-hexahydro-2H-pyrido[2,1-a]isoquinolin-2-ylamine, for carboxylic acid in high-performance liquid chromatography using tris(2,2'-bipyridine)ruthenium(II).

3-Isobutyl-9,10-dimethoxy-1,3,4,6,7,11b-hexahydro-2H-pyrido[2,1-a]isoquinolin-2-ylamine (IDHPIA) was found to be a selective and highly sensitive derivatization reagent for carboxylic acid by high-performance liquid chromatography (HPLC) with electrogenerated chemiluminescence detection using tris(2,2'-bipyridine)ruthenium(II). Free fatty acids and phenylbutylic acid were used as model compounds of carboxylic acids, and the derivatization conditions were optimized with myristic acid. Under the mild reaction conditions of room temperature for 45 min in acetonitrile containing 2-bromo-1-ethylpyridinium tetrafluoroborate and 9-methyl-3,4-dihydro-2H-pyridol1,2-a]pyrimidin-2-one, all the fatty acids tested were reacted with IDHPIA to produce highly sensitive derivatives.

Electrogenerated chemiluminescence derivatization reagents for carboxylic acids and amines in high-performance liquid chromatography using tris(2,2'-bipyridine)ruthenium(II).

2-(2-Aminoethyl)-1-methylpyrrolidine and N-(3-aminopropyl)pyrrolidine (NAPP) were found to be selective and sensitive derivatization reagents for carboxylic acid by high-performance liquid chromatography (HPLC) with electrogenerated chemiluminescence detection using tris(2,2'-bipyridine)ruthenium(II). Free fatty acids and ibuprofen were used as model compounds of carboxylic acids, and the derivatization conditions were optimized with myristic acid as a representative of free fatty acids. All the fatty acids tested were reacted with NAPP to produce highly sensitive derivatives under the mild reaction conditions of room temperature for 30 min in acetonitrile containing 2-bromo-1-ethylpyridinium tetrafluoroborate and 9-methyl-3,4-dihydro-2H-pyrido[1,2-a]pyrimidin-2-one.