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Investigation of the potential correlation between the cognitive status and the levels of brain fatty acids in young and aged C57BL/6 mice

100%

Jakubowska-Dogru E. , Yetimler B. , Ulusoy G. , Celik T.

nr S

The aim of the present study was to investigate the possible relationship between the levels of various brain fatty acids and learning indices in aged (22-23 months old) and young (2-3 months old) female C57BL/6 mice classified as “good” or “poor” learners basing on their performance in a spatial learning task: the Morris water-maze. The levels of several fatty acids including palmitic, stearic, oleic, linoleic, arachidonic (AA), and docosahexaenoic acid (DHA) were measured by gas chromatography in brain tissue samples from four different brain areas: hippocampus, cortex, striatum and hypothalamus. The results of behavioural tests confirmed a decline in learning skills with age. However, a great individual variation was revealed in learning scores between aged subjects indicating that biological aging is not always parallel to chronological aging. The relative levels of palmitic, stearic, oleic, linoleic, arachidonic, and DHA acids in the four examined brain structures were very similar. Interestingly, except hypothalamus, no significant relation has been found between the brain levels of DHA omega-3 acid and the animal’s age or cognitive status. This finding contributes to the current debate on the value of DHA supplementation as an effective protective treatment against aging and dementia. The only significant correlation between learning performance and the brain fatty acid levels was found for arachidonic acid in the young mice hippocampus, structure known to be critical for spatial learning and memory. AA level was significantly lower in young “good learners” as compared to both young “poor learners” and old “good learners” with young “good learners” showing significantly better performance than the two other groups. These results are discussed in the context of recent reports about elevated AA levels in Alzheimer’s dementia.

Stress distribution comparisons of foot bones in patient with tibia vara : a finite element study

75%

Özkan A. , Atmaca H. , Mutlu I. , Celik T. , Ugur L. , Kisioglu Y.

Acta of Bioengineering and Biomechanics

2013

tom Vol. 15, no. 4

67--72

Blount’s disease, or tibia vara, is the most common cause of pathologic genu varum in children and adolescents. Changes in the loading of knee structures such as tibial articular cartilage, menisci and subcondral bone are well documented in case of genu varum. But the mechanical effects of this condition on foot bones are still questionable. In this study, the authors hypothesized that stress distributions on foot bones might increase in patients with tibia vara when compared with patients who had normal lower extremity mechanical axis. Three-dimensional (3D) finite element analyses of human lower limb were used to investigate and compare the loading on foot bones in normal population and patient with tibia vara. The segmentation software, MIMICS was used to generate the 3D images of the bony structures of normal and varus malalignment lower extremity. Except the spaces between the adjacent surface of the phalanges fused, metatarsals, cuneiforms, cuboid, navicular, talus and calcaneus bones were independently developed to form foot and ankle complex. Also femur, tibia and fibula were modeled utilizing mechanical axis. ANSYS version 14 was used for mechanical tests and maximum equivalent stresses (MES) were examined. As a result of the loading conditions, in varus model MES on talus, calcaneus and cuboid were found higher than in normal model. And stress distributions changed through laterally on middle and fore foot in varus deformity model.