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@#Abstract: Objective （ ） To compare the measured results of arsenic in urine by atomic fluorescence spectrometry AFS and - （ - ）， Methods inductively coupled plasma mass spectroscopy ICP MS and analyze the reasons of the difference. The samples WS/T 474-2015 Determination of Arsenic in Urine by Hydride Generation Atomic Fluorescence were pretreated according to Spectrometry， （ ∶ ∶ ∶∶ ，V/V/V） and digested with mixed acid nitric acid sulfuric acid perchloric acid=3 1 1 and then determined by - - AFS and ICP MS. The samples were diluted with 0.50% nitric acid and determined by ICP MS. The samples included urine ， ， （ arsenic quality control samples inorganic arsenic supplemented samples and organic arsenic arsenic choline and arsenic ） - betaine supplemented samples. Standard curve method was used to compare the results of AFS method and ICP MS method. Results （ ） （ ） The results of quality control samples by AFS method digestion and ICP-MS method without digestion were ， - within the range of reference values but the values obtained by AFS method were lower than those obtained by ICP MS method. - - - ， The recovery of AFS and ICP MS was 97.79% 100.82% and 99.55% 99.98% respectively. In the middle and high ， - （ P ） concentration groups the measured values of inorganic arsenic by AFS were lower than that by ICP MS all <0.01 . The （ ） - recovery of arsenic betaine and arsenic choline by AFS method digestion was only 2.17% 2.63%. The values of arsenic betaine （ ） - （ and arsenic choline measured by AFS method digestion were lower than those measured by ICP MS method without ） - （ ）（ P ）Conclusion digestion and ICP MS method digestion all <0.01 . The result of urine arsenic measured by AFS method - ， was lower than that measured by ICP MS method which may be related to the mixed acid digestion of AFS method. Keywords: ； - ； ； ； ； ；
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OBJECTIVE@#To investigate the expression, mechanism and methylation level of miR-28-5p in multiple myeloma (MM), so as to provide the expirement basis for searching new targeted therapy.@*METHODS@#RT-PCR was used to detect the expression levels of miR-28-5p and potential target CCND1 in CD138 cells of the patients with MM and bone marrow mononuclear cells of patients with iron defficiency anemia(IDA) as control, Methylation-specific PCR(MSP) was used to detect methylation levels of CpG island in LPP/miR-28-5p promoter region and the correlation with other clinical indicators was analyzed. The 5-aza-2'-deoxycytidine (5-Aza-dC，DAC) was used to treat MM cell line U266; after drug treatment，MSP was used to analyze the methylation status of the CpG islands in LPP/miR-28-5p promoter; the qPCR was used to detect the expression levels of miR-28-5p，and the regulatory mechanism of miR-28-5p expression was explored furtherly.@*RESULTS@#The methylation level of CpG island in LPP/miR-28-5p promoter region of MM patients was significantly higher than that of IDA patients. The relative expression level of miR-28-5p in MM patients was significantly lower than that of IDA patients. The relative expression level of miR-28-5p in newly diagnosed MM patients was higher than that in relapsed/progressive patients. The miR-28-5p target CCND1 was expressed at high levels in MM patients with LPP / miR-28-5p methylation, the expression level of miR-28-5p in MM patients correlated with β-MG concentration. 5-aza-dc could significantly inhibit the growth of U266 cell line, arrest the cell cycle in G phase, inhibit the biosynthesis of cellular RNA and protein and promote cell apoptosis. At the same time, up-regulation of miR-28-5p expression was found.@*CONCLUSION@#The expression of miR-28-5p in MM patients is regulated by methylation of CpG islands in the promoter region of the genome.miR-28-5p may act as a tumor suppressor gene, and its low expression may be involved in the occurrence and development of MM, suggesting that miR-28-5p may become a new target for the treatment of MM.