Characterizing the Existence of Fluorescence Quenching Agents Using EEM Fluorescence and UV Spectra: Taking the Interaction of Humic Acid and Fe(â ¢) as an Example.

The fluorescence quenching agents was characterized with three-dimensional fluorescence and ultraviolet (UV) spectra. When there was Fe (Ⅲ) in the sample, the humic fluorescence would be quenched and their UV spectra were not affected. The variation of fluorescence intensity (I) at Ex/Em=300/510 nm and UV absorbance(A) at UV300 were investigated in the article. The smaller the ratio of fluorescence intensity versus UV absorbance (I/A) is, the higher the fluorescence quencher Fe(Ⅲ) concentration is. According to Stern-Volmer equation I/I0=1-fc×Kc×[c] /(1+Kc×[c] ) and fitted function I/A=f×[k/(cFe3++c)+b] , the fitted fluorescent quenching constant Kc was ranged between 1.08 to 1.15, the ratio of bounded fluorophores versus total fluorophores, i.e. fc, was ranged between 1.10 to 1.14. The ratio of fluorescence intensity and absorbance of humic acid was fitted with Fe(Ⅲ) concentration and the constants were acquired as following: f=0.83～1.19, k=587.19～612.19, c=0.87～0.92, b=-87.09～-46.36. The correlation curve values were 0.99. The Stern-Volmer formula was used to describe the quenching effect of humic acid fluorescence by Fe (Ⅲ). However, due to the fact that the fluorescence intensity I0 without quencher was difficult to acquire during the analysis of practical samples, the fitted function between the ratio of I/A and Fe(Ⅲ) was used to reflect the quenching effect of Fe(Ⅲ) on the fluorescence of humic acid, which was based on the correlations between the fluorescence intensity I0 and ultraviolet absorbance A. The fitted formula was used to predict the iron ions concentration of the resin separated and concentrated samples from wastewater treatment plant and receiving waters. The predicted values were in good accordance with those determined with inductively coupled plasma atomic emission spectroscopy(ICP-AES) method when the iron ion concentration was above 0.4 mg·L-1, which could be used to ascertain the existence of fluorescence quenching agent and their corresponding concentration.

Association of GSTs gene polymorphisms with treatment outcome of advanced non-small cell lung cancer patients with cisplatin-based chemotherapy.

We evaluated the association of GSTM1 null/present, GSTT1 null/present, and GSTP1 IIe105Val polymorphisms with the clinical response to chemotherapy and treatment outcome of NSCLC. Between October 2009 and October 2012, a total of 282 patients with advanced NSCLC were enrolled into our study, and they were followed up until October 2014. The genotypes of GSTM1, GSTT1, and GSTP1 IIe105Val were performed by polymerase chain reaction (PCR) coupled with restriction fragment length polymorphism (RFLP). By logistic regression analysis, our study found that the Val/Val genotype of GSTP1 IIe105Val was associated with more CR+PR response to chemotherapy when compared with the IIe/IIe genotype, and the OR (95% CI) was 2.18 (1.16-4.12). By multivariate Cox proportional hazards regression analysis, we found the Val/Val genotype of GSTP1 was correlated with lower risk of death in advanced NSCLC (HR, 0.48; 95% CI, 0.25-0.93). However, no association was found between GSTT1 and GSTM1 polymorphisms and response to chemotherapy and overall survival of advanced NSCLC. Moreover, the IIe/Val + Val/Val genotypes of GSTP1 were associated with lower risk of death in never smokers, and the adjusted HR (95% CI) was 0.34 (0.12-0.93). In conclusion, we found that the GSTP1 polymorphism was correlated with better response to chemotherapy and lower risk of death in advanced NSCLC patients.