Browsing by Author "Olivares, Ricardo"

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    Anatomy of corpus callosum in prenatally malnourished rats
    (SOC BIOLGIA CHILE, 2012) Olivares, Ricardo; Morgan, Carlos; Perez, Hernan; Hernandez, Alejandro; Aboitiz, Francisco; Soto Moyano, Ruben; Gil, Julio; Ortiz, Alexis; Flores, Osvaldo; Gimeno, Miguel; Laborda, Jesus
    The effect of prenatal malnutrition on the anatomy of the corpus callosum was assessed in adult rats (45-52 days old). In the prenatally malnourished animals we observed a significant reduction of the corpus callosum total area, partial areas, and perimeter, as compared with normal animals. In addition, the splenium of corpus callosum (posterior fifth) showed a significant decrease of fiber diameters in the myelinated fibers without changing density. There was also a significant decrease in diameter and a significant increase in density of unmyelinated fibers. Measurements of perimeter's fractal dimensions from sagittal sections of the brain and corpus callosum did not show significant differences between malnourished and control animals. These findings indicate that cortico-cortical connections are vulnerable to the prenatal malnutrition, and suggest this may affect interhemispheric conduction velocity, particular), in visual connections (splenium).
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    Interplay between the morphometry of the lungs and the mode of locomotion in birds and mammals
    (2007) Figueroa, Daniela; Olivares, Ricardo; Salaberry, Michel; Sabat, Pablo; Canals, Mauricio
    We studied the lung diffusion parameters of two species of birds and two species-of mammals to explore how structural and functional features may be paralleled by differences in life style or phylogenetic origin. We used two fast-flying species (one mammal and one bird), one running mammal and one bird species that flies only occasionally as models. The harmonic mean thickness of the air-blood barrier was very thin in the species we studied. An exception was the Chilean tinamou Notoprocta perdicaria, which only flies occasionally. It showed an air-blood barrier as thick as that of flightless Galliformes. We found that the respiratory surface density was significantly greater in flying species compared to running species. The estimated values for the oxygen diffusion capacity, 13,02 follow the same pattern: the highest values were obtained in the flying species, the bat and the eared dove. The lowest value was in N. perdicaria. Our findings suggest that the studied species show refinements in their morphometric lung parameters commensurate to their energetic requirements as dictated by their mode of locomotion, rather than their phylogenetic origin. The air-blood barrier appears to be thin in most birds and small mammals, except those with low energetic requirements such as the Chilean tinamou. In the species we studied, the respiratory surface density appears to be the factor most responsive to the energetic requirements of flight.