No abstract

Introduction: Bone diseases, aging and traumas can cause bone loss and lead to bone defects. Treatment of bone defects is challenging, requiring chirurgical procedures. Bone grafts are widely used for bone replacement, but they are limited and expensive. Due to bone graft limitations, natural, semi-synthetic, synthetic and composite materials have been studied as potential bone-graft substitutes. Desirable characteristics of bone-graft substitutes are high osteoinductive and angiogenic potentials, biological safety, biodegradability, bone-like mechanical properties, and reasonable cost. Herein, we prepared and characterized potential bone-graft substitutes composed of calcium phosphate (CP) -a component of natural bone, and chitosan (CS) -a biocompatible biopolymer. Methods: CP-CS composites were synthetized, molded, dried and characterized. The effect of drying temperatures (38 and 60 °C) on the morphology, porosity and chemical composition of the composites was evaluated. As well, the effects of drying temperature and period of drying (3, 24, 48 and 72 hours) on the mechanical properties -compressive strength, modulus of elasticity and relative deformation-of the demolded samples were investigated. Results: Scanning electron microscopy and gas adsorption-desorption analyses of the CS-CP composites showed interconnected pores, indicating that the drying temperature played an important role on pores size and distribution. In addition, drying temperature have altered the color (brownish at 60 °C due to Maillard reaction) and the chemical composition of the samples, confirmed by FTIR. Conclusion: Particularly, prolonged period of drying have improved mechanical properties of the CS-CP composites dried at 38 °C, which can be designed according to the mechanical needs of the replaceable bone.

Palavras-chave:Sistema digestório. Cólon transverso. Eqüino. Cólica. Anatomia regional. Agradecimentos: Trabalho realizado com apoio do CNPq/PIBIC Anatomic and surgical study of the equine transverse colon from left paralombar aprouch AbstractThe transverse colon is a constriction of the bowel lumen, which can be submitted to obstructive process. The knowledge enlargement about this structure and the adjacent ones has a great surgical Key word: Transverse colon. Enterolith. Equine. Colic. Acute abdomen. CT CM M

Often fractures of long bones in horses are comminuted and form bone gaps, which represent a major challenge for the fixation of these fractures by loss of contact between the fragments. Bone grafts help in treating this kind of fracture and synthetic

Purpose Biopolymers, such as chitosan and collagen, have excellent biocompatibility and can be used for bone remodeling. Chitosan and collagen can be crosslinked by glutaraldehyde. The aim of this study was to formulate a chitosan, collagen, and calcium phosphate-based device for potential application as bone substitutes. Methods The device was synthesized, molded, dried, and characterized. Results By FTIR, it was possible to observe a characteristic peak relating to the crosslinking of chitosan and collagen. The images of SEM and BET/BJH results showed the presence of apparent and interconnected pores. TG-DSC have shown two temperature ranges for weight loss. Mechanical tests provided an elastic modulus equal to 239.25 ± 78.37 MPa and maximum tension of 4.33 ± 0.95 MPa, which are comparable to some commercial bone substitutes and other similar synthetic devices. Conclusion The synthesized device showed interconnected pores and surficial porosity, besides thermal stability at physiological temperature, and mechanical properties comparable to spongy bones.