Browsing by Autor "J. L. Beard"

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Defining anaemia and its effect on physical work capacity at high altitudes in the Bolivian Andes
(Cambridge University Press, 1988) J. D. Haas; D. A. Tufts; J. L. Beard; Robert C. Roach; Hilde Spielvogel
Of all the ecozones in the tropics, one of the most challenging in terms of its effects on physical work capacity is found in the high altitude mountains. Not only does one have to contend with many of the health and nutritional problems associated with underdevelopment but one also has to adjust to the reduced atmospheric pressure and partial pressure of oxygen associated with high elevations. Since oxygen is required for all aerobic work, a reduction in oxygen tension will reduce aerobic work capacity unless substantial adaptations occur in systemic oxygen transport and utilisation.
Methaemoglobin and erythrocyte reducing systems in high-altitude natives
(Informa, 1979) J. Arnaud; J.C. Quilici; Nancy Gutiérrez; J. L. Beard; Hugues Vergnes
The stress of chronic hypobaric hypoxia present at high altitudes induces a series of adaptive changes in the intermediate metabolism in erythrocytes of high-altitude natives. Aymaras of the high Andean Plateau are shown to have within erythrocytes: (a) increased activity of NADH2 (GAPDH) generating stages, (b) decreased activity of NADH2 (LDH) consuming steps, (c) significantly increased methaemoglobin content, and (d) a large increase in the level of reduced glutathione. These alterations occur also in persons of the same ethnic group residing at low altitude. There is, however, only a moderate elevation of classic haematological parameters (erythrocyte count, haemoglobin and haematocrit) in highland natives. The functional implications of these metabolite changes are discussed with respect to regulation of erythrocyte metabolism.