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• Erythropoiesis  (1)
• Key words Germanium dioxide  (1)
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• 1
Electronic Resource
Springer
European journal of applied physiology 73 (1996), S. 471-478
ISSN: 1439-6327
Keywords: Altitude ; Hypobaric chamber ; Physical training ; Aerobic metabolism ; Erythropoiesis
Source: Springer Online Journal Archives 1860-2000
Topics: Medicine
Notes: Abstract The effects of training in a hypobaric chamber on aerobic metabolism were studied in five high performance triathletes. During 3 weeks, the subjects modified their usual training schedule (approximately 30 h a week), replacing three sessions of bicycling exercise by three sessions on a cycle ergometer in a hypobaric chamber simulating an altitude of 4,000 m (462 mm Hg). Prior to and after training in the hypobaric chamber the triathletes performed maximal and submaximal exercise in normoxia and hypoxia (462 mm Hg). Respiratory and cardiac parameters were recorded during exercise. Lactacidaemia was measured during maximal exercise. Blood samples were drawn once a week to monitor blood cell parameters and erythropoetin concentrations. Training in the hypobaric chamber had no effect on erythropoiesis, the concentrations of erythropoetin always remaining unchanged, and no effect on the maximal oxygen uptake ( $$\dot V$$ O2max) and maximal aerobic capacity measured in normoxia or hypoxia. Submaximal performance increased by 34% during a submaximal exhausting exercise performed at a simulated altitude of 2,000 m. During a submaximal nonexhausting test, ventilation values tended to decrease for similar exercise intensities after training in hypoxia. The changes in these parameters and the improved performance found for submaximal exercise may have been the result of changes taking place in muscle tissue or the result of training the respiratory muscles.
Type of Medium: Electronic Resource
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• 2
Electronic Resource
Springer
Physics and chemistry of minerals 27 (2000), S. 575-582
ISSN: 1432-2021
Keywords: Key words Germanium dioxide ; High pressure phase transition ; Rietveld refinement
Source: Springer Online Journal Archives 1860-2000
Topics: Chemistry and Pharmacology , Geosciences , Physics
Notes: Abstract  Germanium dioxide was found to undergo a transition from the tetragonal rutile-type to the orthorhombic CaCl2-type phase above 25 GPa. The detailed structural evolution of both phases at high pressure in a diamond anvil cell has been investigated by Rietveld refinement using angle-dispersive, X-ray powder-diffraction data. The square of the spontaneous strain (a−b)/(a+b) in the orthorhombic phase was found to be a linear function of pressure and no discontinuities in the cell constants and volume were observed, indicating that the transition is second-order and proper ferroelastic. Compression of the GeO6 octahedra was found to be anisotropic, with the apical Ge-O distances decreasing to a greater extent than the equatorial distances and becoming shorter than the latter above 7 GPa. Above this pressure, the GeO6 octahedron exhibits the common type of tetragonal distortion predicted by a simple ionic model and observed for most rutile-type structures such as those of the heavier group-14 dioxides and the metal difluorides. Above the phase transition, the columns of edge-sharing octahedra tilt about their two fold axes parallel to c and the rotation angle reaches 10.2(5)° by 36(1) GPa so as to yield a hexagonal close-packed oxygen sublattice. The compressibility increases at the phase change as is expected for a second-order transition at which an additional compression mechanism becomes available.
Type of Medium: Electronic Resource
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• 3
Electronic Resource
Springer
Cell & tissue research 284 (1996), S. 373-381
ISSN: 1432-0878
Keywords: Key words: Retinoids ; Vaginal epithelium ; Differentiation ; Keratin ; Apoptosis ; Estradiol ; Progesterone ; Rat (Wistar)
Source: Springer Online Journal Archives 1860-2000
Topics: Biology , Medicine
Notes: Abstract. In rodents, the vaginal epithelium shows cyclic changes with an alternating pattern of keratinization under estrogen control and mucification under progesterone control. Retinoids are powerful regulators of cell differentiation, an excess of retinoids suppressing the keratinizing differentiation of keratinocytes. Here, we have examined the vaginal epithelium during the estrous cycle and compare the effects of retinoids on both types of hormonally induced differentiation, i.e. keratinization and mucification. All-trans retinoic acid was administred either by daily injections during the estrous cycle or by a single injection before the estrogen rise; these two protocols gave similar results. Retinoic acid suppressed estrogen-induced vaginal keratinization and cytokeratin K10 expression (a biochemical marker of terminal differentiation). Progesterone-induced mucification was not impaired; however, retinoic acid impeded mucous cell desquamation, suggesting an effect of retinoic acid on cell adhesiveness. Retinoic acid induced the appearance of apoptotic-like cells, as revealed by immunocytochemical staining of DNA fragmentation.
Type of Medium: Electronic Resource
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