Currently, information regarding isomer-specific concentrations of PFHxS, PFOS, and PFOA in human placenta, and corresponding placental-maternal ratios (R) of these compounds does not exist. The objective of the present study was to assess the occurrence, and distribution of different PFHxS, PFOS, and PFOA isomers in maternal serum, umbilical cord serum, and placenta to gain a better understanding of transplacental transport efficiency and prenatal exposure risks. The study involved quantitative determination of isomer-specific concentrations of PFHxS, PFOS, and PFOA in samples of maternal serum (n = 32), cord serum (n = 32), and placenta (n = 32) from pregnant women in Wuhan, China. The results indicate that both linear and branched PFHxS, PFOS and PFOA can be efficiently transported across the placenta, with exposure levels ordered maternal serum > cord serum > placenta. For PFOS isomers, the concentration ratios between cord serum and maternal serum (R) were ordered n < iso < 4m < (3 + 5)m < 1m < ∑m. The R values exhibited a similar trend for branched PFOS isomers: iso < 4m ≈ (3 + 5)m < 1m ≈ ∑m. Conversely, PFOA isomers did not exhibit an obvious structure-activity relationship for R and R. n-PFHxS transported across the placenta to a greater extent than br-PFHxS. To the best of our knowledge, this is the first study to report the occurrence of PFHxS, PFOS, and PFOA isomers in human placenta. Further, R values of these compounds are reported here for the first time. The findings help to better understand the mechanisms of the placental transfer and neonatal exposure to these important contaminants of concern.
Currently, information regarding concentrations of chlorinated polyfluoroalkyl ether sulfonic acids (Cl-PFESAs) in human placenta does not exist. The main objective of this study was to assess the occurrence and distribution of two Cl-PFESAs, 6:2 Cl-PFESA and 8:2 Cl-PFESA, in maternal serum, umbilical cord serum, and placenta to better assess the transport pathways related to human prenatal exposure. The widely studied perfluorooctanesulfonate (PFOS) was studied for comparison. This study was a hospital-based survey involving quantitative determination of Cl-PFESA and PFOS concentrations in maternal serum (n = 32), cord serum (n = 32), and placenta (n = 32) samples from women in Wuhan, China. The results indicate that Cl-PFESAs can efficiently be transported across placenta, with median exposure levels of 0.60 and 0.01 ng/mL for 6:2 Cl-PFESA and 8:2 Cl-PFESA in the cord sera, respectively. Concentrations of the target compounds in maternal sera, cord sera, and placentas decreased in the following order: PFOS > 6:2 Cl-PFESA > 8:2 Cl-PFESA. Similar patterns were observed in maternal sera, cord sera, and placentas for Cl-PFESAs, with concentrations decreasing in the following order: maternal sera > cord sera > placentas. Significant correlations were observed among 6:2 Cl-PFESA, 8:2 Cl-PFESA, and PFOS concentrations in the maternal serum, cord serum, and placenta samples (r > 0.7; p < 0.001). The median value of R (ratio of cord serum to maternal serum concentration) of 6:2 Cl-PFESA was 0.403, indicating a relatively high (∼40%) placental transfer efficiency. 8:2 Cl-PFESA was transported across placenta to a greater extent than 6:2 Cl-PFESA was, likely because of its higher hydrophobicity and lower plasma protein binding affinity. To the best of our knowledge, this is the first study to report the occurrence and distribution of 6:2 Cl-PFESA and 8:2 Cl-PFESA in human placenta. The findings improve our understanding of the mechanisms of transplacental transfer and neonatal exposure to these important PFOS alternatives.
Soil salinity is one of the major abiotic stresses that reduces agricultural productivity and affects large terrestrial areas around the world. Germination is the starting point of the growth and development process of all crops, and it is severely affected by salt stress. Sweet sorghum (Sorghum bicolor (L.) Moench.) is one of the most promising crops that has a relatively high salt tolerance and biomass. However, few studies have evaluated the salt tolerance or screened the reliable evaluation traits of sweet sorghum. In this study, the membership function value of five traits was used as a comprehensive index for the evaluation and selection of salt tolerance in 300 sweet sorghum germplasms. After salt tolerance evaluation, 23 highly salt-tolerant, 38 salt-tolerant, 195 moderately salt-tolerant, 38 salt-sensitive and 6 highly salt-sensitive germplasms during the germination stage were screened. Moreover, the germination index under the 200 mM NaCl treatment showed the highest correlation with salt tolerance during the germination stage. This information can be used for effectively evaluating sweet sorghum during the germination stage. These results are important for the evaluation of the salt tolerance of sweet sorghum germplasms during the germination stage.
Host-gut microbiota metabolic interactions are closely associated with health and disease. A manifestation of such co-metabolism is the vast structural diversity of bile acids (BAs) involving both oxidative stereochemistry and conjugation. Herein, we describe the development and validation of a LC-MS-based method for the analysis of human C24 BA metabolome in serum and urine. The method has high throughput covering the discrimination of oxidative stereochemistry of unconjugated species in a 15-min analytical cycle. The validated quantitative performance provided an indirect way to ascertain the conjugation patterns of BAs via enzyme-digestion protocols that incorporated the enzymes, sulfatase, β-glucuronidase, and choloylglycine hydrolase. Application of the method has led to the detection of at least 70 unconjugated BAs including 27 known species and 43 newly found species in the post-prandial serum and urine samples from 7 nonalcoholic steatohepatitis patients and 13 healthy volunteers. Newly identified unconjugated BAs included 3α, 12β-dihydroxy-5β-cholan-24-oic acid, 12α-hydroxy-3-oxo-5β-cholan-24-oic acid, and 3α, 7α, 12β-trihydroxy-5β-cholan-24-oic acid. High-definition negative fragment spectra of the other major unknown species were acquired to facilitate future identification endeavors. An extensive conjugation pattern is the major reason for the "invisibility" of the newly found BAs to other common analytical methods. Metabolomic analysis of the total unconjugated BA profile in combination with analysis of their conjugation patterns and urinary excretion tendencies have provided substantial insights into the interconnected roles of host and gut microbiota in maintaining BA homeostasis. It was proposed that the urinary total BA profile may serve as an ideal footprint for the functional status of the host-gut microbial BA co-metabolism. In summary, this work provided a powerful tool for human C24 BA metabolome analysis that bridges the gap between GC-MS techniques in the past age and LC-MS techniques currently prevailing in biomedical researches. Further applications of the present method in clinical, translational research, and other biomedical explorations will continue to boost the construction of a host-gut microbial co-metabolism network of BAs and thus facilitate the decryption of BA-mediated host-gut microbiota crosstalk in health and diseases. Graphical abstract ᅟ.
The gut microbiota modifies endogenous primary bile acids (BAs) to produce exogenous secondary BAs, which may be further metabolized by cytochrome P450 enzymes (P450s). Our primary aim was to examine how the host adapts to the stress of microbe-derived secondary BAs by P450-mediated oxidative modifications on the steroid nucleus. Five unconjugated tri-hydroxyl BAs that were structurally and/or biologically associated with deoxycholate (DCA) were determined in human biologic samples by liquid chromatographytandem mass spectrometry in combination with enzyme-digestion techniques. They were identified as DCA-19-ol, DCA-6b-ol, DCA-5bol, DCA-6a-ol, DCA-1b-ol, and DCA-4b-ol based on matching in-laboratory synthesized standards. Metabolic inhibition assays in human liver microsomes and recombinant P450 assays revealed that CYP3A4 and CYP3A7 were responsible for the regioselective oxidations of both DCA and its conjugated forms, glycodeoxycholate (GDCA) and taurodeoxycholate (TDCA). The modification of secondary BAs to tertiary BAs defines a host liver (primary BAs)-gut microbiota (secondary BAs)-host liver (tertiary BAs) axis. The regioselective oxidations of DCA, GDCA, and TDCA by CYP3A4 and CYP3A7 may help eliminate host-toxic DCA species. The 19-and 4b-hydroxylation of DCA species demonstrated outstanding CYP3A7 selectivity and may be useful as indicators of CYP3A7 activity.
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