20 research outputs found
Involvement of the endocannabinoid system in the physiological response to transient common carotid artery occlusion and reperfusion
Background: The transient global cerebral hypoperfusion/reperfusion achieved by induction of Bilateral Common Carotid Artery Occlusion followed by Reperfusion (BCCAO/R) may trigger a physiological response in an attempt to preserve tissue and function integrity. There are several candidate molecules among which the endocannabinoid system (ECS) and/or peroxisome-proliferator activated receptor-alpha (PPAR-alpha) may play a role in modulating oxidative stress and inflammation. The aims of the present study are to evaluate whether the ECS, the enzyme cyclooxygenase-2 (COX-2) and PPAR-alpha are involved during BCCAO/R in rat brain, and to identify possible markers of the ongoing BCCAO/R-induced challenge in plasma. Methods: Adult Wistar rats underwent BCCAO/R with 30 min hypoperfusion followed by 60 min reperfusion. The frontal and temporal-occipital cortices and plasma were analyzed by high performance liquid chromatography-mass spectrometry (HPLC-MS) to determine concentrations of endocannabinoids (eCBs) and related molecules behaving as ligands of PPAR-alpha, and of oxidative-stress markers such as lipoperoxides, while Western Blot and immunohistochemistry were used to study protein expression of cannabinoid receptors, COX-2 and PPAR-alpha. Unpaired Student's t-test was used to evaluate statistical differences between groups. Results: The acute BCCAO/R procedure is followed by increased brain tissue levels of the eCBs 2-arachidonoylglycerol and anandamide, palmitoylethanolamide, an avid ligand of PPAR-alpha, lipoperoxides, type 1 (CB1) and type 2 (CB2) cannabinoid receptors, and COX-2, and decreased brain tissue concentrations of docosahexaenoic acid (DHA), one of the major targets of lipid peroxidation. In plasma, increased levels of anandamide and lipoperoxides were observed. Conclusions: The BCCAO/R stimulated early molecular changes that can be easily traced in brain tissue and plasma, and that are indicative of the tissue physiological response to the reperfusion-induced oxidative stress and inflammation. The observed variations suggest that the positive modulation of the ECS and the increase of proinflammatory substances are directly correlated events. Increase of plasmatic levels of anandamide and lipoperoxides further suggests that dysregulation of these molecules may be taken as an indicator of an ongoing hypoperfusion/reperfusion challenge
Experimental investigation into reparative osteogenesis with fibrin adhesive
An experimental investigation was carried out in order to evaluate the effects of fibrin adhesive on the reparative osteogenesis of bone grafts in the short, medium, and long term. Sixty fully developed New Zealand White rabbits under general anesthesia were grafted with homologous bone tissue in the proximal third of each tibias. Fibrin adhesive was used in one hind limb only. The animals were killed at a predetermined time. Both tibias were removed and subjected to radiographic and histologic analyses. The reparative process was observed and the differences between the fibrin adhesive-treated grafts and the reference group in the first few weeks were determined. No substantial difference was detected in the reparative osteogenetic process of the graft in the animals killed after 2 months. © 1988 Springer-Verlag
Experimental investigation into the reparative osteogenesis with the fibrine adhesive.
Archives of Orthopaedics and Traumatic Surger
The action of loads on bone tissue
This paper analyses the effect of mechanical loading on bone remodelling under both physiological and pathological conditions. The sensitivity and the type of the biological response of bone to the changes in mechanical loading are conditioned by several factors: individual race and age, pattern of stress, systemic and local metabolic conditions, etc. Therefore, bone remodelling following mechanical stress is not only a simple repair process, but a complex mechanism of functional adaptation which is controlled by the strain magnitude of bone structure rather than the extent of the stress. Results show that the skeletal changes induced by mechanical stress involve not only the structural properties but also the material characteristics of bone. For example, the size of hydroxyapatite crystals increases under load. These findings allow us to hypothesize that mechanical stress could directly modify the mineral component of bone. Hydroxyapatite appears to be a highly dynamic structure, able to change its crystallinity in relation to external stimuli. It is thus conceivable that hydroxyapatite crystals gather and arient themselves along bone and improve their crystallinity not only under the influence of biological mechanisms, but also as a reaction to mechanical stimuli