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- Nascimento, V. B., et al.
(författare)
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Surface-Stabilized Nonferromagnetic Ordering of a Layered Ferromagnetic Manganite
- 2009
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 103:22, s. 227201-
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Tidskriftsartikel (refereegranskat)abstract
- An outstanding question regarding the probing or possible device applications of correlated electronic materials (CEMs) with layered structure is the extent to which their bulk and surface properties differ or not. The broken translational symmetry at the surface can lead to distinct functionality due to the charge, lattice, orbital, and spin coupling. Here we report on the case of bilayered manganites with hole doping levels corresponding to bulk ferromagnetic order. We find that, although the hole doping level is measured to be the same as in the bulk, the surface layer is not ferromagnetic. Further, our low-energy electron diffraction and x-ray measurements show that there is a c-axis collapse in the outermost layer. Bulk theoretical calculations reveal that, even at fixed doping level, the relaxation of the Jahn-Teller distortion at the surface is consistent with the stabilization of an A-type antiferromagnetic state.
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- Pialoux, V., et al.
(författare)
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Effects of exercise and training in hypoxia on antioxidant/pro-oxidant balance
- 2006
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Ingår i: European Journal of Clinical Nutrition. - London, United Kingdom : Nature Publishing Group. - 0954-3007 .- 1476-5640. ; 60:12, s. 1345-54
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The aim was to investigate the effects of acute exercise under hypoxic condition and the repetition of such exercise in a 'living low-training high' training on the antioxidant/prooxidant balance.Design: Randomized, repeated measures design.Setting: Faculté de Médecine, Clermont-Ferrand, France.Subjects: Fourteen runners were randomly divided into two groups. A 6-week endurance training protocol integrated two running sessions per week at the second ventilatory threshold into the usual training.Intervention: A 6-week endurance training protocol integrated two running sessions per week at the second ventilatory threshold into the usual training. The first hypoxic group (HG, n=8) carried out these sessions under hypoxia (3000 m simulated altitude) and the second normoxic group (NG, n=6) in normoxia. In control period, the runners were submitted to two incremental cycling tests performed in normoxia and under hypoxia (simulated altitude of 3000 m). Plasma levels of advanced oxidation protein products (AOPP), malondialdehydes (MDA) and lipid oxidizability, ferric-reducing antioxidant power (FRAP), lipid-soluble antioxidants (alpha-tocopherol and beta-carotene) normalized for triacyglycerols and cholesterol were measured before and after the two incremental tests and at rest before and after training.Results: No significant changes of MDA and AOPP level were observed after normoxic exercise, whereas hypoxic exercise induced a 56% rise of MDA and a 44% rise of AOPP. Plasma level of MDA and arterial oxygen hemoglobin desaturations after the acute both exercises were highly correlated (r=0.73). alpha-Tocopherol normalized for cholesterol and triacyglycerols increased only after hypoxic exercise (10-12%, P<0.01). After training, FRAP resting values (-21%, P<0.05) and alpha-tocopherol/triacyglycerols ratio (-24%, P<0.05) were diminished for HG, whereas NG values remained unchanged.Conclusions: Intense exercise and hypoxia exposure may have a cumulative effect on oxidative stress. As a consequence, the repetition of such exercise characterizing the 'living low-training high' model has weakened the antioxidant capacities of the athletes.Sponsorship: International Olympic Committee and the Direction Régionale de la Jeunesse et des Sports de la Région Auvergne.
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- Hermann-Kleiter, Natascha, et al.
(författare)
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Lasp1 misexpression influences chondrocyte differentiation in the vertebral column
- 2009
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Ingår i: International Journal of Developmental Biology. - : UPV/EHU Press. - 1696-3547 .- 0214-6282. ; 53:7, s. 983-991
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Tidskriftsartikel (refereegranskat)abstract
- The mouse mutant wavy tail Tg(Col1a1-lacZ)304ng was created through transgene insertion and exhibits defects of the vertebral column. Homozygous mutant animals have compressed tail vertebrae and wedge-shaped intervertebral discs, resulting in a meandering tail. Delayed closure of lumbar neural arches and lack of processus spinosi have been observed; these defects become most prominent during the transition from cartilage to bone. The spina bifida was resistant to folic acid treatment, while retinoic acid administration caused severe skeletal defects in the mutant, but none in wild type control animals. The transgene integrated at chromosome 11 band D, in an area of high gene density. The insertion site was located between the transcription start sites of the RpI23 and Lasp1 genes. LASP1 (an actin binding protein involved in cell migration and survival) was found to be produced in resting and hypertrophic chondrocytes in the vertebrae. In mutant vertebrae, temporal and spatial misexpression of Lasp1 was observed, indicating that alterations in Lasp1 transcription are most likely responsible for the observed phenotype. These data reveal a yet unappreciated role of Lasp1 in chondrocyte differentiation during cartilage to bone transition.
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