Siderophores were produced and secreted with marine microorganisms as the highly specific iron chelators. A method of liquid chromatography-tandem mass spectrometric detection coupled with solid phase extraction pretreatment was developed for the determination of siderophores in seawater. The samples were filtered through a 0. 22 μm membrane, extracted with an ENVI-18 cartridge and then eluted with methanol. The separation of the analytes was performed on a reversed phase SB-C18 column with a gradient elution program by using 0. 1% ( V/V) formic acid and methanol as the mobile phases. Qualitative analysis was performed in multiple-reaction monitoring mode. Good linearity (R2>0. 99) was obtained for Pyoverdines-Fe, Ferrichrome, Ferrioxamine E at the concentrations of 0. 001-3. 00 μg/mL, 0. 005-15. 00 μg/mL, 0. 001-3. 00 μg/mL, respectively. The instrumental detection limits and limits of quantification for the three analytes were 0. 08, 1. 76 and 1. 36 ng/mL; 0. 27, 5. 87 and 4. 53 ng/mL, respectively. The relative standard deviations were lower than 12%, while the recoveries were 12. 1%-18. 6% for Pyoverdines-Fe, 82. 0%-97. 7% for Ferrichrome, and 70. 0%-98. 3% for Ferrioxamine E.

Objective:To analyze the prognosis and influencing factors of different radiotherapy modes in patients with brain metastases from non-small cell lung cancer (NSCLC), and to explore the best benefit population with radiotherapy boost under different prognostic scores.Methods:634 patients with brain metastasis from NSCLC admitted to the Fourth Hospital of Hebei Medical University from 2013 to 2015 were analyzed retrospectively. According to different radiotherapy modes, they were divided into three groups: no radiotherapy group ( n=330), whole-brain radiotherapy group (WBRT)( n=127) and whole-brain radiotherapy combined with boost group (WBRT+ boost)( n=177). The intracranial progression-free survival (iPFS) and overall survival (OS) were calculated by Kaplan-Meier method. The multivariate prognostic factors were analyzed by the Cox models. Results:The median iPFS and OS of all patients were 6.9 months and 9.0 months, respectively. In the no radiotherapy, WBRT and WBRT+ boost groups, the 1-year iPFS was 15.1%, 16.3% and 40.2%( P=0.002), and the 1-year OS was 33.7%, 38.2% and 48.1%( P<0.001), respectively. Multivariate survival analysis demonstrated that different radiotherapy modes were the independent factors affecting iPFS and OS. Subgroup analysis revealed that for patients with 1-3 brain metastases, the 1-year OS and iPFS in the WBRT+ boost group were better than those of WBRT alone ( P=0.026, P=0.044) when GPA score was 2.5-4.0; the 1-year OS and iPFSin the WBRT+ boost group were better than those of WBRT alone ( P=0.036, P=0.049) when there was no targeted therapy; for patients with ≥4 brain metastases, the 1-year iPFS in the WBRT+ boost group was better than that of WBRT alone ( P=0.019, P=0.012) when GPA score was 2.5-4.0 and there was no targeted therapy. When the GPA score was 0-2 or there was targeted therapy, the 1-year OS and iPFS in the WBRT+ boost group were better than those of WBRT alone, but the difference was not statistically significant (all P>0.05). Conclusions:Radiotherapy can significantly improve the iPFS and OS of NSCLC patients with brain metastases. When the number of brain metastases is 1-3, GPA score is 2.5-4.0 or no targeted therapy, boost may improve the iPFS and OS; when the number of brain metastases is more than 4, GPA score is 2.5-4.0 or no targeted therapy, boost may only bring iPFS benefit; when GPA score is 0-2 or targeted therapy, boost may not benefit significantly.