Browsing by Autor "J. Arnaud"

Now showing 1 - 4 of 4

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.
High-altitude haematology: Quechua-Aymara comparisons
(Informa, 1981) J. Arnaud; J.C. Quilici; Germaine Rivière
Haematological studies have been carried out at various altitudes between 450 m and 4800 m, on two separate human groups (Quechuas and Aymaras) living in South America. Changes in the haematological parameters do not develop linearly in relation to the attitude. Th impact of chronic hypoxia on erythropoiesis is greater above 3000 m. The haemogram varies quantitatively and not qualitatively (mean corpuscular volume and mean haemoglobin concentration remain constant). The haematological study also reveals the greater adaptability to high altitude of the Aymaras, an adaptability characterized by an increase in red cell count and concentration and a decrease in red cell volume. The adaptative phenomena observed in the Quechuas are reversible, whereas they persist in the Aymaras when they migrate to the lowlands (450 m).
Human red cell glycolysis in high altitude chronic hypoxia
(Wiley, 1984) J. Arnaud; Nancy Gutiérrez
We have found that glycolysis in human red blood cells under the hypoxic conditions found at high altitudes is connected with changes in enzyme activities and levels of various metabolic intermediates. The sensitivity of the four kinases to hypoxia results in 1) glycolytic hyperactivity leading to a higher intracellular energy state, and 2) accumulation of 2-3 DPG, whose role in the adaptation of red blood cell respiration to high altitude has been shown by previous research. PEP, 3PG , and G6P appear to be the main regulating intermediates in glycolysis in this system. The reason for the very large increase in G1- 6DP is still not clear.
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.