ABSTRACT
Objective@#A new ion exchange column technology was used to establish an efficient and sensitive method for the detection of inorganic arsenic.@*Methods@#Based on the new As Specia Fast Column, the pretreatment methods, liquid phase separation and mass spectrometry determination conditions of inorganic arsenic in rice were optimized. Finally, arsenic compounds were separated by As Specia Fast Column and detected by liquid chromatography inductively coupled plasma mass spectrometry. The external standard method was used for quantitative analysis. The detection limit, precision and accuracy of the method were determined by measuring the content of arsenic compounds in rice samples and rice standard samples. At the same time, three Guangdong rice samples were selected as the experimental samples of this study, and 1 g of each sample was weighed and measured in parallel three times. The method was compared with the method of liquid chromatography-atomic fluorescence spectrometry (LC-AFS) and liquid chromatography-inductively coupled plasma mass spectrometry (LC-ICP-MS) in the national standard.@*Results@#The inorganic arsenic in rice was extracted with 0.5% nitric acid solution at 65 ℃ for 15 h, and the pH was adjusted to alkaline. The mobile phase A (8 mmol/L HNO3, 50 mmol/L NH3·H2O) and mobile phase B (40 mmol/L HNO3, 80 mmol/L NH3·H2O) were used as the mobile phase gradient elution (93%) . Five arsenic compounds can reach baseline separation under the conditions of RF power of 1 500 W and atomization gas flow of 0.97 L/min. The detection limits ranged from 0.114 to 0.331 μg/L, and the inorganic arsenic content in rice samples ranged from 0.063 to 0.232 mg/kg. The results of determination of arsenic compounds in rice flour reference materials were all within the uncertainty range indicated by the standard. The recoveries were 86.7%~106.7%, and the precision was 1.9%-12.5%. Compared with national standards, the results of determination of arsenate in rice were relatively close (using this method, LC-AFS, LC-ICP-MS to detect the content of arsenate in rice samples 1 was 0.231, 0.226, 0.236 mg/kg, respectively). However, due to insufficient sensitivity, the national standard method is difficult to detect low levels of arsenic compounds (Arsenobetaine was not detected in rice sample 1). The method can detect the content of arsenobetaine in rice sample 1 was 0.023 mg/kg.@*Conclusion@#The established method can meet the requirements of inorganic arsenic determination in rice, and it is more rapid and accurate than the current national standard. It can better monitor and evaluate the content of i-As in rice, and provide accurate data for comprehensively grasping and evaluating the safety of rice consumption of residents.
ABSTRACT
Objective To investigate the expression of TLR4 mRNA and NF-κB p65 in colorectal carcinomas and adjacent normal colon tissue, and evaluate their roles in the pathogenesis and development in colorectal carcinoma. Methods Sixty-three colorectal carcinoma samples and respective adjacent normal colon tissue samples ( well differentiated : 23 cases; moderately differentiated: 17 cases; poorly differentiated:20 cases; other differentiated type: 3 cases; lymph node metastasis: 27 cases; no lymph node metastasis:36 cases; Dukes A: 18cases;Dukes B: 14 cases Dukes C: 22 cases; Dukes D: 9 cases) were collected. The expression of TLR4 mRNA in colorectal carcinomas and adjacent tissue were detected by RT-PCR. The expression of NF-κB p65 was detected by WB. Results The expression of TLR4 mRNA in colorectal carcinomas and adjacent tissue were 86.42 ± 15.16 and 32.74 ± 9.44. It was significantly higher in carcinoma tissue than that in adjacent tissue ( t = 22.354, P ＜ 0.01 ). The expression of TLR4 mRNA in well, moderately and poorly differentiated coiorectal carcinomas were 69.58 ± 11.27, 64.57 ± 13.91 and 97.12 ± 15.44 respectively. TLR4 mRNA in poorly differentiated colorectal carcinomas was significantly higher than that in well, moderately differentiated ones ( t = 11.304 and 12.223, P ＜ 0.01 ). There was no difference between lymph node metastatic carcinomas ( 89.91 ± 13.33 ) and carcinomas without metastasis (81.16±13.59,t =0.959,P＞0.05). The expression of TLR4 mRNA in the Dukes A stage tumors (59.05±11.66) was lower than that in Dukes B(90.34 ±0.08),C(91.41 ± 15.21), D(101.46 ±17.43), respectively ( t = 8.708,9.664,9.525, P ＜ 0.05 ). The expression of NF-κB p65 in colorectal carcinoma(0.63 ±0.11) was significant higher than that in adjacent tissue(0.34 ±0.08,t = 18.266,P ＜0.01 ). The expression of NF-κB p65 in well, moderately and poorly differentiated colorectal carcinomas were 0.46 ± 0.09, 0.72 ± 0.11 and 0.77 ± 0.14, respectively. The experssion of NF-κB p65 in well differentiated colorectal carcinomas was obviously lower than the woderately and poorly differentiated carcinomas (t = 11.223 and 10.875, P ＜0.01 ). There was significant difference between the expression of p65 in lymph node metastatic carcinomas(0.82 ± 0.17) and non-metastatic carcinomas(0.57 ± 0.12, t =18.269,P＜0.05). The expression of NF-κB p65 in Dukes A colorectal carcinomas (0.39 ± 0.06) was lower compared with the Dukes B(0.72 ±0.12), C(0.69 ±0.14) and D carcinomas(0.76 ±0.13,t =10.442, 9.889 and 9.721, P ＜ 0.01 ). Conclusions The enhanced expression of TLR4/NF-κB p65 are closely associate with clinical stage and pathologic grade. NF-κB p65 may be an molecular marker of lymph node metastatic. The increased expression of TLR4/NF-κB p65 promote the pathogenesis and development of colorectal carcinoma.