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A Sevin

Publications and source records attributed to A Sevin.

22 records · Page 2Linked to original sources
PubMed1979

Scattering of cerebral blood flow estimates using 133Xe intracarotid injection.

Computer-generated and real curves were used to study the random error in the blood flow estimates calculated from xenon-133 cerebral clearance curves. The initial count rate affects the scattering under a threshold of 5,000 counts/s, but above this figure its influence is negligible. Flow values, relative weight of gray matter, and processes of analysis have also an effect. For the stochastic analysis, a theoretical standard deviation calculable from each experimental curve was proved. For other methods, empirical formulas were established. Using these formulas, intervals of uncertainty can be calculated allowing a useful comparison of the results obtained on the same patient, from different areas or from subsequent tests. Such intervals also allow the comparison of mean flow values obtained from a particular curve by the three usual processes of analysis. With high initial count rates, more than 75% of the intervals of uncertainty are disjointed. This suggests that the random error plays little part in the differences observed.

Cerebrovascular Circulation↗
PubMedDate not supplied

GM and KM immunoglobulin allotypes in a Spanish Pyrenean population: Val d'Aran.

Four hundred and thirteen unrelated individuals (202 autochthonous and 211 non-autochthonous) of Val d'Aran (Catalan Pyrenees) have been analysed for the GM and KM immunoglobulin genetic system using the inhibition haemagglutination method. This population was defined by eight GM haplotypes (GM*3 23 5*, GM*3 5*, GM*1,17 21,28, GM*1,2,17 21,28, GM*1,17 5*, GM*1,17 5,6,11,24, GM*1,17 10,11,13,15 and GM*1,17 10,11,13,15,16) inferred from the 17 observed phenotypes. The Val d'Aran population frequencies conform to Hardy-Weinberg expectations. The frequencies of phenotypes and haplotypes show a definite homogeneity between the autochthonous and non-autochthonous people of Val d'Aran and 11 other Pyrenean populations (Mauléon, Macaye, St. Jean Pied de Port, Vallée de L'Ouzom, Gavarnie, Barèges, Luz St. Sauveur, Esparros, Camurac, Capcir and Pays de Sault) that have already been studied for the same allotypes. A factorial correspondence analysis was performed for the 12 autochthonous Pyrenean populations, showing a high frequency of the GM*3 23 5* haplotype in the three Pyrenean regions (Western, Central and Eastern), while the GM*1,17 21,28 haplotype is mainly found in the Central region, GM*3 5* in the Eastern and Western zones, and the GM*1,2,17 21,28 is mainly present in the Central and Eastern populations. The results show a relative regional homogeneity, so there is no evidence of a frequency gradient in the Pyrenean populations for the GM and KM genetic systems. It may, however, be noticed that the Central Pyrenean populations form a group, with one population (Vallée de l'Ouzom) isolated from the rest, probably because of its particular model of inheritance by which the heritage is passed to the first born without sex consideration. It has been possible to point out some differences in the genetic structure of the autochthonous and non-autochthonous Val d'Aran population and to place the autochthonous Aranese group among its Pyrenean neighbours.

Ethnicity↗