| 1. |
|
|
| 2. |
- Liu, Yanna, et al.
(författare)
-
Temporal trends of perfluorooctanesulfonate isomer and enantiomer patterns in archived Swedish and American serum samples
- 2015
-
Ingår i: Environment International. - : Elsevier BV. - 0160-4120 .- 1873-6750. ; 75, s. 215-222
-
Tidskriftsartikel (refereegranskat)abstract
- Human perfluorooctanesulfonate (PFOS) body burdens are attributable to both direct PFOS and indirect PFOS precursor (PreFOS) exposure. The relative importance of these two pathways has been estimated, but the relative temporal trajectory of exposure to PFOS and PreFOS has not been examined. Here, two hypothesized biomarkers of PreFOS exposure, PFOS isomer profiles (quantified as percent branched PFOS, %br-PFOS) and chiral 1m-PFOS enantiomer fractions (1m-PFOS EF) were analyzed in archived human serum samples of individual American adults (1974-2010) and pooled samples of Swedish primiparous women (1996-2010). After correcting for potential confounders, significant correlations between %br-PFOS and 1m-PFOS EFs were observed in American samples and in Swedish samples for the 1996-2000 period, supporting the hypothesis that both %br-PFOS and 1m-PFOS EF are biomarkers of PreFOS exposure. Significant trends of increasing %br-PFOS, from 2000 to 2010, and increasingly non-racemic 1m-PFOS EFs, from 1996 to 2000, were detected in Swedish samples. No statistically significant trend for %br-PFOS or 1m-PFOS EF was observed in American samples, but American males had significantly higher %br-PFOS and significantly lower 1m-PFOS EF (i.e. more non-racemic) than females, and a similar significant difference was shown in the older age group, relative to the younger age group. These temporal trends in %br-PFOS and 1m-PFOS EF are not easily explained and the results highlight uncertainties about how humans are exposed to PFOS.
|
|
| 3. |
- Aspenström-Fagerlund, Bitte, et al.
(författare)
-
Fatty acids increase paracellular absorption of aluminium across Caco-2 cell monolayers
- 2009
-
Ingår i: Chemico-Biological Interactions. - : Elsevier BV. - 0009-2797 .- 1872-7786. ; 181:2, s. 272-278
-
Tidskriftsartikel (refereegranskat)abstract
- Passive paracellular absorption, regulated by tight junctions (TJs), is the main route for absorption of poorly absorbed hydrophilic substances. Surface active substances, such as fatty acids, may enhance absorption of these substances by affecting the integrity of TJ and increasing the permeability. It has been suggested that aluminium (Al) absorption occurs mainly by the paracellular route. Herein, we investigated if physiologically relevant exposures of fully differentiated Caco-2 cell monolayers to oleic acid and docosahexaenoic acid (DHA), which are fatty acids common in food, increase absorption of Al and the paracellular marker mannitol. In an Al toxicity test, mannitol and Al absorption through Caco-2 cell monolayers were similarly modulated by Al concentrations between 1 and 30mM, suggesting that absorption of the two compounds occurred via the same pathways. Exposure of Caco-2 cell monolayers to non-toxic concentrations of Al (2mM) and (14)C-mannitol in fatty acid emulsions (15 and 30mM oleic acid, 5 and 10mM DHA) caused a decreased transepithelial electrical resistance (TEER). Concomitantly, fractional absorption of Al and mannitol, expressed as percentage of apical Al and mannitol retrieved at the basolateral side, increased with increasing dose of fatty acids. Transmission electron microscopy was applied to assess the effect of oleic acid on the morphology of TJ. It was shown that oleic acid caused a less structured morphology of TJ in Caco-2 cell monolayers. Taken together our findings indicate that fatty acids common in food increase the paracellular intestinal absorption of Al. These findings may influence future risk assessment of human Al exposure.
|
|
| 4. |
- Aspenström-Fagerlund, Bitte, et al.
(författare)
-
Oleic acid and docosahexaenoic acid cause an increase in the paracellular absorption of hydrophilic compounds in an experimental model of human absorptive enterocytes
- 2007
-
Ingår i: Toxicology. - : Elsevier BV. - 0300-483X .- 1879-3185. ; 237:1-3, s. 12-23
-
Tidskriftsartikel (refereegranskat)abstract
- Surface active compounds present in food possibly have the ability to enhance the absorption of water soluble toxic agents. Therefore, we investigated whether fatty acids such as oleic acid and docosahexaenoic acid (DHA), both commonly present in food, negatively affect the integrity of tight junctions (TJ) in the intestinal epithelium and thereby increase the absorption of poorly absorbed hydrophilic substances. Caco-2 cells, which are derived from human absorptive enterocytes, were grown on permeable filters for 20-25 days. Differentiated cell monolayers were apically exposed for 90min to mannitol in emulsions of oleic acid (5, 15 or 30mM) or DHA (5, 15 or 30mM) in an experimental medium with or without Ca(2+) and Mg(2+). Absorption of (14)C-mannitol increased and trans-epithelial electrical resistance (TEER) decreased in cell monolayers exposed to oleic acid and DHA, compared to controls. Cytotoxicity, measured as leakage of LDH, was higher in groups exposed to 30mM oleic acid and all concentrations of DHA. Morphology of the cell monolayers was studied by using fluorescence microscopy. Exposure of cell monolayers to 5mM DHA for 90min resulted in a profound alteration of the cell-cell contacts as detected by staining the cells for beta-catenin. Oleic acid (30mM) treatment also induced dissolution of the cell-cell contacts but the effect was not as pronounced as with DHA. Cell monolayers were also exposed for 180min to 250nM cadmium (Cd) in emulsions of oleic acid (5 or 30mM) or DHA (1 or 5mM), in an experimental medium with Ca(2+) and Mg(2+). Retention of Cd in Caco-2 cells was higher after exposure to 5mM oleic acid but lower after exposure to 30mM oleic acid and DHA. Absorption of Cd through the monolayers increased after DHA exposure but not after exposure to oleic acid. Our results indicate that fatty acids may compromise the integrity of the intestinal epithelium and that certain lipids in food may enhance the paracellular absorption of poorly absorbed hydrophilic substances.
|
|
| 5. |
- Aspenström-Fagerlund, Bitte, et al.
(författare)
-
Oleic acid decreases BCRP mediated efflux of mitoxantrone in Caco-2 cell monolayers
- 2012
-
Ingår i: Food and Chemical Toxicology. - : Elsevier BV. - 0278-6915 .- 1873-6351. ; 50:10, s. 3635-3645
-
Tidskriftsartikel (refereegranskat)abstract
- Breast cancer resistance protein (BCRP) efflux restricts intestinal absorption of substances like heterocyclic amines, mycotoxins and certain human and veterinary drugs. Fat rich meals seem to increase absorption of drugs which are BCRP substrates or inhibitors. We therefore hypothesize that absorption of toxicants normally effluxed by BCRP are increased by fatty acids in food. Transport across and accumulation of H-3-Mitoxantrone (MXR) in Caco-2 cell monolayers were measured after 60 min exposure to emulsions of H-3-MXR (1 mu M) and oleic acid (0.5-5 mM). In addition, BCRP gene expression (RT-PCR) and the amount of BCRP protein (Western blot) were measured in oleic acid exposed Caco-2 cells. Oleic acid increased transport of MXR in a concentration dependent manner and 2 mM oleic acid or higher increased accumulation of MXR in cells, without any signs of cytotoxicity. Gene expression of BCRP was increased after exposure to oleic acid for 6 h, but the amount of BCRP protein was not increased. In conclusion, oleic acid clearly induced BCRP gene expression and reduced BCRP mediated efflux, although the amount of BCRP in cells was not affected. Consequently, effects of fatty acids on BCRP mediated efflux are important to consider in risk assessment of toxicants in food.
|
|
| 6. |
- Aspenström-Fagerlund, Bitte, et al.
(författare)
-
Oleic acid increases intestinal absorption of the BCRP/ABCG2 substrate, mitoxantrone, in mice
- 2015
-
Ingår i: Toxicology Letters. - : Elsevier BV. - 0378-4274 .- 1879-3169. ; 237:2, s. 133-139
-
Tidskriftsartikel (refereegranskat)abstract
- The efflux transporter breast cancer resistance protein (BCRP/ABCG2) decrease intestinal absorption of many food toxicants. Oleic acid increases absorption of the specific BCRP substrate mitoxantrone (MXR), and also BCRP gene expression in human intestinal Caco-2 cells, suggesting that oleic acid affect the BCRP function. Here, we investigated the effect of oleic acid on intestinal absorption of MXR in mice. Mice were orally dosed with 2.4 g oleic acid/kg b.w. and 1 mg MXR/kg b.w., and sacrificed 30, 60, 90 or 120 min after exposure, or were exposed to 0.6, 2.4 or 4.8 g oleic acid/kg b.w. and 1mg MXR/kg b.w., and sacrificed 90 min after exposure. Mice were also treated with Ko143 together with MXR and sacrificed after 60 min, as a positive control of BCRP-mediated effects on MXR absorption. Absorption of MXR increased after exposure to oleic acid at all doses, and also after exposure to Ko143. Intestinal BCRP gene expression tended to increase 120 min after oleic acid exposure. Our results in mice demonstrate that oleic acid decreases BCRP-mediated efflux, causing increased intestinal MXR absorption in mice. These findings may have implications in humans, concomitantly exposed to oleic acid and food contaminants that, similarly as MXR, are substrates of BCRP.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
|
|
