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- Bretillon, L, et al.
(författare)
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Plasma levels of 24S-hydroxycholesterol in patients with neurological diseases
- 2000
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Ingår i: Neuroscience Letters. - 0304-3940. ; 293:2, s. 87-90
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Tidskriftsartikel (refereegranskat)abstract
- The brain is the exclusive or almost exclusive site of formation of 24S-hydroxycholesterol and we have shown that the circulating level of 24S-hydroxycholesterol is dependent upon the relation between cerebral production and hepatic clearance. In the present work we determined plasma levels of 24S-hydroxycholesterol in patients with various neurological diseases. Eleven subjects with brain death occurring 6-10 h before collection of the plasma samples had markedly reduced circulating levels of 24S-hydroxycholesterol (-43%, P<0.001). Patients with advanced Alzheimer's disease and cerebral inflammatory diseases had slightly lower levels of 24S-hydroxycholesterol in plasma when compared to matched controls. Patients with acute ischemic stroke, multiple sclerosis and primary brain tumors had levels not significantly different from those of controls. The conditions leading to reduced plasma levels of 24S-hydroxycholesterol had no significant effect on plasma levels of another side-chain oxidized oxysterol, 27-hydroxycholesterol. Except for conditions characterized by very marked destruction of the central nervous system, different severe neurological diseases seem to have relatively small effects on the flux of 24S-hydroxycholesterol from the brain.
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- Cornelissen, G., et al.
(författare)
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Effect of sorbate planarity on environmental black carbon sorption
- 2004
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 38:13, s. 3574-3580
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Tidskriftsartikel (refereegranskat)abstract
- Soot and charcoal, collectively termed "black carbon" or BC, can exhibit extremely strong sorption of many hydrophobic organic compounds. In order to include BC sorption in fate models, it is important to know BC nanopore surface areas. In addition, it is useful to know for which compounds BC sorption can be expected to be important. By nitrogen adsorption measurements at ultralow pressures on sediment that was strongly enriched in BC by HF treatment and/or chemothermal oxidation at 375 degreesC, we found that environmental BC has nanoporosity in the <4-10 Angstrom size range. The nanopore surface area (<50 Angstrom) of BC in Lake Ketelmeer (The Netherlands) sediment was approximately 58 m(2)/g. We measured sorption isotherms over a wide concentration interval for four compounds with the same K-OW (10(4.6+/-0.1)): planar anthracene (ANT), phenanthrene (PHE), and 4-chlorobiphenyl (4-PCB) along with nonplanar 2,2'-dichlorobiphenyl (2,2'-PCB). The environmental BC sorption coefficients of these iso-K-OW compounds decreased in the order ANT > PHE approximate to 4-PCB much greater than 2,2'-PCB and spanned a factor of 50-200, depending on concentration. Nonplanar 2,2'-PCB showed much more linear BC sorption (n(F) = 0.92) than the planar compounds (n(F) = 0.54-0.70). This shows that steric hindrance strongly attenuates BC-sorbate interactions for a nonplanar PCB. Thus, BC is more important for environmental sorption of planar compounds (>50% sorbed to BC in the nanogram per liter range) than for nonplanar ones (<10-20%). Using the measured BC nanopore surface area, a close agreement between modeled and measured BC sorption data could be found.
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- Kobayashi, T, et al.
(författare)
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Lack of antibody production against Hanganutziu-Deicher (H-D) antigens with N-glycolylneuraminic acid in patients with porcine exposure history.
- 2000
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Ingår i: Xenotransplantation. - : Wiley. - 0908-665X. ; 7:3, s. 177-80
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Tidskriftsartikel (refereegranskat)abstract
- The significance of non-alphagalactosyl antigens remains unclear in pig-to-primate xenotransplantation. Hanganutziu-Deicher (H-D) antigens with terminal N-glycolylneuraminic acid (NeuGc) are widely expressed on endothelial cells of mammalian species, with the exception of humans. As baboons and monkeys also express H-D antigens, a pig-to-non-human primate experimental model cannot resolve the question of whether H-D antigens can elicit a potent humoral response in human recipients. The purpose of this study was to elucidate the clinical significance of H-D antigens by examining the sera from patients who have been previously exposed to porcine tissue. After the digestion of porcine aortic endothelial cells (PAEC) by neuraminidase, NeuGc and N-acetylneuraminic acid (NeuAc) were quantitated by HPLC. IgG and IgM antibody levels against H-D antigens were measured by NeuGc-GM3-coated ELISA plates in the sera of patients who had undergone ex vivo kidney perfusion 1 to 3 weeks and 2 years previously (n=2) or had been injected with fetal porcine islets 2 months previously (n= 10). HPLC determined that 9.7x 10(7) NeuAc and 6.3x 10(7) NeuGc residues per cell were released from PAEC by neuraminidase, while 25.7x 10(7) NeuAc and an undetectable level of NeuGc were released from human aortic endothelial cells (HAEC). No significant elevation of IgG or IgM antibody levels against NeuGc-GM3 was observed in sera from patients with a history of porcine exposure. Considering the active production of antibody against the foreign galactosyl antigens after pig-to-human xenotransplantation, some production of antibodies against the equally foreign H-D antigens would be expected, because large amounts of NeuGc terminated saccharides are present in the pig endothelial cell surface. However, no production of antibodies directed to H-D antigens could be found in patients exposed to porcine tissue. Further studies are warranted to explain why H-D antigens do not elicit a significant antibody production.
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