1.[Determination of N-carbamyl-L-glutamic acid in feedstuff by high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry].
Tang S, Wang Y, Wen P, Xin Z. Se Pu. 2014 Feb;32(2):184-8.
A method was developed for the determination of N-carbamyl-L-glutamic acid (NCG) in feedstuff by high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). The feedstuff samples were extracted with methanol, cleaned-up by a ProElut mixed-mode of strong anion exchange inverse column (PXA). Then the samples were separated with HPLC and detected with MS/MS in multiple reaction monitoring (MRM) mode via positive electrospray ionization (ESI+). The fragment ions of m/z 148.0 and m/z 84.0 were used for qualitative analysis, and m/z 130.0 was selected for quantitative analysis. The limit of detection for NCG was 24 microg/kg (S/N > 3), and the limit of quantification was 80 microg/kg (S/N > 10). The standard calibration curve was linear over the range of 20-1,000 microg/L, and the correlation coefficient was 0. 999 9. The recoveries of NCG in feedstuff were 104.0%, 103.5%, 95.3%, at the three spiked levels of 80, 200, 500 mg/kg with the relative standard deviations (RSDs) of 7.
2.A liver-specific defect of Acyl-CoA degradation produces hyperammonemia, hypoglycemia and a distinct hepatic Acyl-CoA pattern.
Gauthier N1, Wu JW, Wang SP, Allard P, Mamer OA, Sweetman L, Moser AB, Kratz L, Alvarez F, Robitaille Y, Lépine F, Mitchell GA. PLoS One. 2013 Jul 5;8(7):e60581. doi: 10.1371/journal.pone.0060581. Print 2013.
Most conditions detected by expanded newborn screening result from deficiency of one of the enzymes that degrade acyl-coenzyme A (CoA) esters in mitochondria. The role of acyl-CoAs in the pathophysiology of these disorders is poorly understood, in part because CoA esters are intracellular and samples are not generally available from human patients. We created a mouse model of one such condition, deficiency of 3-hydroxy-3-methylglutaryl-CoA lyase (HL), in liver (HLLKO mice). HL catalyses a reaction of ketone body synthesis and of leucine degradation. Chronic HL deficiency and acute crises each produced distinct abnormal liver acyl-CoA patterns, which would not be predictable from levels of urine organic acids and plasma acylcarnitines. In HLLKO hepatocytes, ketogenesis was undetectable. Carboxylation of [2-(14)C] pyruvate diminished following incubation of HLLKO hepatocytes with the leucine metabolite 2-ketoisocaproate (KIC). HLLKO mice also had suppression of the normal hyperglycemic response to a systemic pyruvate load, a measure of gluconeogenesis.
