Glutamine is the most abundant amino acid found in plasma and cells. It is the preferred fuel for enterocytes in the small intestine, macrophages, and lymphocytes. After serious burn, increased requirement of glutamine by the gastrointestinal tract, kidney and lymphocytes, and relatively insufficient self synthesis likely contribute to the rapid decline of glutamine in circulation and cells. Glutamine supplementation can not only protect intestinal mucosa, maintain normal intestinal barrier function, reduce bacterial translocation, and enhance the intestinal immune function, but also increase the number of lymphocytes, enhance the phagocytic function of macrophage, promote the synthesis of immunoglobulin, and reduce the body′s inflammatory response, so as to enhance the immune function. Therefore, glutamine supplementation can improve and enhance the immune function, reduce complications and promote the prognosis of severely burned patients.

Objective:To evaluate the performance of magnetic beads extraction method (MGE) for the measurement of catecholamine metabolites by liquid chromatography tandem mass spectrometry.Methods:This is a methodological evaluation study. The linearity, limit of quantitation, recovery, precision, and matrix effect of catecholamine metabolites 3-methoxyepinephrine (MN), 3-methoxynorepinephrine (NMN) and 3-methoxytyramine (3-MT) extracted by MGE method were evaluated according to CLSI C62-A. Consensus of method development and validation of liquid chromatography-tandem mass spectrometry in clinical laboratories and other guidelines, 132 clinical residual plasma samples were collected and extracted by automated MGE and traditional solid phase extraction (SPE) method to compare the harmonization of the two extraction methods.Results:The linearity of MN, NMN and 3-MT extracted by automated MGE was>0.99, and the LOQ for MN, NMN and 3-MT were 0.033 5 nmol/L, 0.054 7 nmol/L and 0.011 0 nmol/L, respectively. The repeatability of MN, NMN and 3-MT were 1.3%-5.1%, 2.2%-5.6% and 1.7%-7.1%, respectively. The total imprecision in the laboratory were 1.5%-8.2%, 2.2%-7.7%, 2.1%-11.2%. Although the absolute recovery is low, the average relative recoveries of MN, NMN and 3-MT were 91.5%-108.5%, 92.0%-108.6%, and 89.3%-104.1%, respectively, and the percentage deviation from the expected concentration was within 15%. After isotope internal standard correction, the relative matrix effect is close to 100%, which can compensate for the potential matrix effect. The results of MGE and SPE of MN, NMN and 3-MT showeda good correlation (correlation coefficient r>0.99). The average relative deviations of MN, NMN and 3-MT were 0.2%, -1.4% and 1.0%, respectively. Conclusion:The automatic MGE method hasa good performance in extracting catecholamine metabolites, and is expected to be used in high-throughput analysis of samples in clinical in the future.

Tetrandrine(TET),a natural bisbenzyl isoquinoline alkaloid extracted from Stephania tetrandra S.Moore,has diverse pharmacological effects.However,its effects on melanoma remain unclear.Cellular prolif-eration assays,multi-omics analyses,and xenograft models were used to determine the effect of TET on melanoma.The direct target of TET was identified using biotin-TET pull-down liquid chromatograph-mass spectrometry(LC-MS),cellular thermal shift assays,and isothermal titration calorimetry(ITC)analysis.Our findings revealed that TET treatment induced robust cellular autophagy depending on activating transcription factor 6(ATF6)-mediated endoplasmic reticulum(ER)stress.Simultaneously,it hindered autophagic flux by inducing cytoskeletal protein depolymerization in melanoma cells.TET treatment resulted in excessive accumulation of reactive oxygen species(ROS)and simultaneously triggered mitophagy.Sirtuin 5(SIRT5)was ultimately found to be a direct target of TET.Mechanistically,TET led to the degradation of SIRT5 via the ubiquitin(Ub)-26S proteasome system.SIRT5 knockdown induced ROS accumulation,whereas SIRT5 overexpression attenuated the TET-induced ROS accumula-tion and autophagy.Importantly,TET exhibited anti-cancer effects in xenograft models depending on SIRT5 expression.This study highlights the potential of TET as an antimelanoma agent that targets SIRT5.These findings provide a promising avenue for the use of TET in melanoma treatment and underscore its potential as a therapeutic candidate.