Aspects cliniques et paracliniques des amputations du pied diabétique au Mali

Introduction. La plaie du pied diabétique est une affection fréquente (10% des motifs d'hospitalisation) et grave, le risque d'amputation étant de 10 à 30 fois plus élevé chez les diabétiques par rapport à la population générale. Elle n'a que peu été étudiée au Mali. Objectif. Décrire les aspects cliniques, thérapeutiques et pronostiques des amputations du pied diabétique au Mali. Méthodologie. II s'agit d'une étude descriptive et transversale qui s'est déroulée à l'Hôpital du Mali du 1er Juillet 2016 au 30 Juin 2017. Elle a porté sur les patients diabétiques présentant une plaie du pied, hospitalisés dans le service de médecine et endocrinologie de l'Hôpital du Mali Les données recueillies et analysées étaient les données sociodémographiques, les données relatives au diabète, les données relatives au pied, les bilans biologiques récents, les radiographies standards, l'échographie doppler artériel des membres. Pour classer le pied atteint, nous avons utilisé la classification de l'Université de Texas. Résultats. Vingt-cinq (25) patients diabétiques ont été recrutés. Le sex ratio était de 0,66. Tous les patients avaient une artériopathie, 96% avaient une neuropathie, et 80% avaient un pied mixte. Un mauvais équilibre glycémique était noté chez 64% des patients ; une ostéite radiologique dans 52% des cas. En outre, 23 patients (92%) avaient un risque d'amputation à 100% selon la classification de l'Université du Texas. 12 patients (46%) avaient été amputés au niveau de la jambe. Nous avons enregistré un décès (4%). Conclusion. L'amputation du pied diabétique affecte surtout la diabétique de sexe féminin avec un mauvais équilibre glycémique. Dans la moitié des cas, elle a lieu au niveau de la jambe

Contrast sensitivity and retinal ganglion cell responses in the primate

Human contrast sensitivity is considered in relation to the responses delivered by retinal ganglion cells of the primate to luminance and chromatic contrast. At different temporal frequencies, response amplitude relative to response variability determines the limit to sensitivity of a single ganglion cell. This can be related to specific models of central detection mechanisms. Both for luminance and chromatic contrast, psychophysical sensitivity to temporal modulation can be achieved by summation of activity of just a few cells that provide input to a detection mechanism. This analysis is then extended to a spatial context. Several sets of data indicate that, in spatial terms, detection mechanisms are of limited spatial extent, and that, at least in the case of luminance patterns, eye movements play a critical role in contrast detection.

Parallel pathways in the retina of old and new world primates

Old-world simians are all trichromats, but in most new-world primates there is a polymorphism; males are dichromats but most females are trichromats. In the old world simian, luminance and red-green chromatic channels defined by psychophysical experiments have as a basis parasol ganglion cells of the magnocellular (MC) pathway and midget ganglion cells of the parvocellular (PC) pathway respectively. Small bistratified ganglion cells provide a basis for a blue-yellow chromatic channel, which should probably be considered a separate entity. In both dichromatic and trichromatic new-world animals, the MC pathway and the small bistratified, blue-yellow system seem anatomically and physiologically similar to those in their old-world relatives. The midget ganglion cells of the parvocellular pathway in trichromats are anatomically and physiologically similar to the old-world pattern. In dichromatic animals, they are anatomically similar and physiologically resemble those of trichromatic animals, except for the lack of chromatic opponency. We conclude that these three systems may form a basic pattern for the visual pathway of primates. However, the results from dichromats indicate that the evolution of trichromacy may be found to be more complex than presently supposed.

The retinal ganglion cell classes of New World primates

In the primate retina there are distinct ganglion cell classes, exhibiting paarticular morphologies and central projections, each responsible for conveying particular types of visual information to the brain. The chief retinal imputs to the cortex arise from specific ganglion cell classes, M-ganglion cells, responsible for carrying the luminance signal, and P-ganglion cells, that convey the red-green color oppnent signal, as well as high contrast luminance signal. There are other ganglion cell classes, such as small-field bistratified cells, exhibiting dentrites that stratify at two different levels in the inner plexiform layer, which convey the blue-yellow color oppnent signal. Most published data concerning primate retinal ganglion cell anatomy and physiology have been obtained from Old World species. Studies on New World monkeys have recently become of interest since they differ from the Old World monkeys with respect to the color vivion inheritance pattern. On reviewing retinal ganglion cell layer organization in New World monkeys, it seems that there are more similarities than differences in relation to the Old Work monkeys. Diurnal genera of New World monkeys exhibit a well-developed fovea centralis and ganglion cell density peak, as well as peripheral density values which are in the range reported for Old World monkeys and human. Moreover, all the major ganglion cell classes identified in Old World monkeys are also present in New World primates. Up to now, no obvious anatomical differences between dechromats and trichromats have been reported. The only genus that is significantly different from the others is the Aotus. It exhibits lower ganglion cell density in the central retina, and apparently lacks the small-field bistratified cells.