Isomer–Specific Distribution of Perfluoroalkyl Substances in Blood

Perfluoroalkyl substances (PFASs) such as perfluorohexanesulfonate (PFHxS), perfluorooctanoate (PFOA), perfluorooctanesulfonate (PFOS) and PFOS–precursors are routinely measured in human plasma and serum, but their relative abundance in the blood cell fraction has not been carefully examined, particularly at the isomer–specific level. Human plasma and whole blood were collected and partitioning behaviors of PFASs and their isomers between plasma and blood cells were investigated. In human samples, mass fraction in plasma (<i>F</i>_p) for PFASs increased among perfluoroalkyl carboxylates as the carbon chain length increased from C6 (mean 0.24) to C11 (0.87), indicating preference for the plasma fraction with increasing chain length. However, among perfluoroalkyl sulfonates, PFHxS (mean 0.87) had a slightly higher <i>F</i>_p than PFOS (0.85). In vitro assays with spiked Sprague–Dawley rat blood were also conducted, and the results showed that PFOS–precursors had lower <i>F</i>_p values than perfluoroalkyl acids, with perfluoroctanesulfonamide having the lowest <i>F</i>_p (mean 0.24). Consistently, linear isomers of PFOS and PFOS–precursors had lower mean <i>F</i>_p than their corresponding total branched isomers. Multiplying by a factor of 2 is not a reasonable method to convert from whole blood to plasma PFAS concentrations, and current ratios could be used as more accurate conversion factors

Additional file 3 of Tumor size as a significant prognostic factor in T1 gastric cancer: a Surveillance, Epidemiology, and End Results (SEER) database analysis

Additional file 3: Supplementary table 2. Univariate and Multivariate analysis of prognostic factors affecting CS

Additional file 2 of Tumor size as a significant prognostic factor in T1 gastric cancer: a Surveillance, Epidemiology, and End Results (SEER) database analysis

Additional file 2: Supplementary table 1. Univariate and Multivariate analysis of prognostic factors affecting OS

Additional file 8 of Tumor size as a significant prognostic factor in T1 gastric cancer: a Surveillance, Epidemiology, and End Results (SEER) database analysis

Additional file 8

Additional file 5 of Tumor size as a significant prognostic factor in T1 gastric cancer: a Surveillance, Epidemiology, and End Results (SEER) database analysis

Additional file 5: Supplementary table 3. Discriminatory ability of clinicopathological factors in predicting OS in gastric cancer

Additional file 4 of Tumor size as a significant prognostic factor in T1 gastric cancer: a Surveillance, Epidemiology, and End Results (SEER) database analysis

Additional file 4: Supplementary figure 2. Heatmap of C-index of clinicopathological factors in predicting CSS and OS in gastric cancer

Additional file 6 of Tumor size as a significant prognostic factor in T1 gastric cancer: a Surveillance, Epidemiology, and End Results (SEER) database analysis

Additional file 6: Supplementary table 4. C-index of clinicopathological factors in subgroup

Additional file 1 of Tumor size as a significant prognostic factor in T1 gastric cancer: a Surveillance, Epidemiology, and End Results (SEER) database analysis

Additional file 1. Material and Methods

Additional file 7 of Tumor size as a significant prognostic factor in T1 gastric cancer: a Surveillance, Epidemiology, and End Results (SEER) database analysis

Additional file 7: Supplementary figure 3. Survival analysis of CSS and OS stratified by tumor size

Trophic Magnification and Isomer Fractionation of Perfluoroalkyl Substances in the Food Web of Taihu Lake, China

Biomagnification of perfluoroalkyl substances (PFASs) are well studied in marine food webs, but related information in fresh water ecosystem and knowledge on fractionation of their isomers along the food web are limited. The distribution, bioaccumulation, magnification, and isomer fractionation of PFASs were investigated in a food web of Taihu Lake, China. Perfluorooctanesulfonate (PFOS) and perfluorocarboxylates (PFCAs) with longer carbon chain lengths, such as perfluorodecanoate (PFDA) and perfluoroundecanoate (PFUnA), were predominant in organisms, while perfluorohexanoate (PFHxA) and perfluorooctanoate (∑PFOA) contributed more in the water phase. The consistent profile signature of PFOA isomers in water phase with 3M electrochemical fluorination (ECF) products suggests that ECF production of PFOA still exists in China. Linear proportions of PFOA, PFOS and perfluorooctane sulfonamide (PFOSA) in the biota were in the range of 91.9–100%, 78.6–95.5%, and 72.2–95.5%, respectively, indicating preferential bioaccumulation of linear isomers in biota. Trophic magnification factors (TMFs) were estimated for PFDA (2.43), perfluorododecanoate (PFDoA) (2.68) and PFOS (3.46) when all biota were included, suggesting that PFOS and long-chained PFCAs are biomagnified in the fresh water food web. The TMF of PFOS isomers descended in the order: <i>n</i>-PFOS (3.86) > 3+5<i>m</i>-PFOS (3.35) > 4<i>m</i>-PFOS (3.32) > 1<i>m</i>-PFOS (2.92) > <i>m</i>₂-PFOS (2.67) > <i>iso</i>-PFOS (2.59), which is roughly identical to their elution order on a FluoroSep-RP Octyl column, suggesting that hydrophobicity may be an important contributor for isomer discrimination in biota