Browsing by Autor "Hugues Vergnes"

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Haematology and erythrocyte metabolism in man at high altitude: An Aymara‐Quechua comparison
(Wiley, 1985) J. Arnaud; Nancy Gutiérrez; Wilma Téllez; Hugues Vergnes
In the course of haematological and biological investigations among Aymara and Quechua populations in Bolivia, an anthropological study of the erythrocytary respiratory function was carried out on the two groups at two altitudes: 3,600 m and 450 m. A difference in the intensity of the biological variations of the two populations is observed at high altitude. In the Quechuas, as in any lowland native, the adaptative phenomena are totally and quickly reversible. In the Aymaras, we detected the existence of more marked haematological and biochemical characters: moderate polycythemia, hyperhaemoglobinemia, microcytosis, metabolical hyperactivity with accumulation of 2-3 di-phosphoglycerate and ATP, and methaemoglobinemia with a drop in the activity of the methaemoglobin reductases. The Aymaras preserve some of those characters (methaemoglobinemia excepted) when they settle in lowlands.
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.
Methaemoglobin in Man Living at High Altitude
(Wiley, 1975) D. Gourdin; Hugues Vergnes; N. Gutierez
Methaemoglobin has been found in the red cells of subjects living permanently at high altitudes (above 3500 m). The level of methaemoglobin appeared to be inversely related to the red cell count and was much increased in anaemic subjects. The methaemoglobinaemia disappeared when the subjects descended to low altitude. The mechanism of this methaemoglobinaemia is not clear. Its presence appears to be related to the hypoxia of altitude, for toxic factors, enzymopenia and the presence of haemoglobin M were eliminated. The regulation of the oxygen dissociation curve in this condition is discussed.