Andréa Pacheco Batista Borges

Hidroxiapatita sintética como substituto ósseo em defeito experimental provocado no terço proximal da tíbia em cão: aspectos à microscopia eletrônica de transmissão

With the objective of studying the synthetic hydroxyapatite (HAP-91) as a bone substitute, eight healthy mongrel adult dogs were used. Following the habitual anesthetic and surgical protocol, a bone defect was provoked in the proximal diafisis of the left and right tibias, being implanted the graft of HAP-91 just in the right tibia. The animals, two at each time, were sacrificed at the 8th, 30th, 60th and 120th days after the surgery, when lesion samples were obtained for histopathology, submitted to the double coloration in 1% uranil acetate solution and in lead citrate solution. These sections were examined and photographed in an electronic transmission microscope. The bone tissue components were identified both in the control and treated tibia. The absorption of HAP-91 was characterized by the presence of multinuclear cells in the interface between the hydroxyapatite and the bone, morphologically considered as osteoclasts. In addition, the concomitant presence of HAP-91, with the adjacent formation of new bone was found, which suggests that the osteointegration of HAP-91 is similar to the bone reabsorption apposition normal process.

Biocompatibilidade e comportamento de compósitos de hidroxiapatita em falha óssea na ulna de coelhos

Composites of synthetic hydroxyapatite and carbon (HAC) and synthetic hydroxyapatite, carbon and sodium biacid phosphate (HACF), both of them in solid form, as substitute in bone regeneration were studied. Thirty-six rabbits divided in three groups were used. After routine anesthetic and surgical procedure, a bone fragment with two-centimeter in length was taken from the middle part of the left ulna. Animals from group 1 received one block of HAC and HACF, from group 2 received only HAC, in the criated bone defect, and animals from group 3 did not receive any treatment. They were submitted to clinical and radiographic examinations at 8, 15, 30, 60, 120 and 180 days after surgery to evaluate bone healing. At the same dates, two animals of each group were enthanised and bone fragments were collected for histological evaluations. The results showed normal evolution of bone regeneration in all groups but faster in animals that received the composites. The use of HAC and HACF showed to be efficient and biocompatible, and not caused rejection.

Estudo experimental do poliuretano de óleo de mamona (Ricinus communis) como substituto parcial do tendão calcâneo comum em coelhos (Oryctolagus cuniculus)

With the goal of evaluating the efficiency of a prosthesis of castor-oil plant (Ricinus communis) polyurethane as a partial substitute for common calcaneous tendon, 30 New Zealand female rabbits, aging between two to three months, weighting about 2kg were used. After general anesthesia, the surgical procedure in both members consisted of rear lateral longitudinal incision, in the medium third of the distal of tibia and exposition of the common calcaneous tendon. After the tenectomies of the gastrocnemius muscle tendon, the polyurethane prosthesis of about 0,5cm in length by 0,5 in diameter was seized to the proximal and distal of the tendon stumps, using polypropylene 4-0 suture just like the Keessler modified technique. The prosthesis of polyurethane in the form of elastomers revealed qualities like the texture and flexibility similar to the tendon tissue, and it can be made in the form and size desired. In addition, it can be shaped, cut and sterilized in wet heat. All animals could stand on the surgically treated members immediately after the end of anesthetic effect. No clinical signs of infection and no dehiscence of the cut were observed. An increase of local volume, due to the edema, evident in the first week after the surgery could be noted, which gradually disappeared. It was possible to detect easily upon touch the prosthesis which remained fixed in place. Clinically, the polyurethane of castor-oil plant did not induce any unfavorable reaction which could compromise the tendon healing and can be indicated as a temporary substitute of a tendon.

Comparison of in vivo properties of hydroxyapatite-polyhydroxybutyrate composites assessed for bone substitution.

This study compared 3 composites made of hydroxyapatite and polyhydroxybutyrate to determine their biocompatibility, osteointegration, and osteoconduction in rabbits bone defects. Hydroxyapatite-polyhydroxybutyrate was tested in a 10:90 vol/vol ratio for composite 1, 25:75 for composite 2, and 50:50 for composite 3, whereas defects in the control group remained unfilled. Limbs were clinically and radiographically evaluated, and samples were taken 8, 45, and 90 days after surgery for histologic and histomorphometrical analysis. No significant difference was found in the clinical parameters: pain, lameness, dehiscence, infection, and edema among the 4 groups. No signs of osteolysis or periosteal reaction were observed. Bone regeneration in groups 1, 2, and 3 occurred histomorphologically similar to the control group. No inflammatory infiltrate was present on any date of observation. More bone than connective tissue was significantly found in the defects of the 3 groups on all observation dates, and the percentage of bone tissue in the interface was similar for composites 2 and 3. Bone and connective tissue were observed in pores of composites 2 and 3. Osteoclasts were found in the bone-composite interface, and multinucleated giant cells were seen on the surface of composite fragments, found among mesenchymal tissue on the 45th and 90th days. No significant difference was observed in osteoclast number among the 4 groups. In summary, composites were considered biocompatible and able to integrate to bone. They also showed signs of biodegradability, and composites 2 and 3 were osteoconductive, the first displaying best characteristics for bone substitution.

Hidroxiapatita sintética pura, hidroxiapatita sintética associada ao colágeno e hidroxiapatita sintética associada ao lipossoma como substitutos ósseos em defeitos provocados na tíbia de cães: aspectos da osteointegração à microscopia de luz transmitida

The objective of this work was to evaluate histologically the synthetic hydroxyapatite (HAP-91), associated to collagen (COL.HAP-91) and associated to liposome (INT.HAP-91), as bone substitutes. Fourty clinically healthy dogs were studied. After a conventional anaesthesic protocol, the surgical procedure consisted of skin incision on medial surface in the left tibial third middle. A bone fragment of 10 ´ 6mm in size was retreated in all animals, which were divided into four groups with 10 animals each. Group one was treated with HAP-91, group two with COL.HAP-91, group three with INT.HAP-91, group four did not receive any treatment and was used as a control. Histological material was collected after humane sacrifice of two animals from each group in 8, 30, 60, 120 180 days after surgery. By the 8th day, bone neoformation in control group and around the implant in groups treated with HAP-91 and INT.HAP-91 was observed. On the 30th day, the defect was filled up completely in the same groups, result which was not observed in COL.HAP-91 group. Bone repair was complete in control group, HAP-91 group and INT.HAP-91 group (most premature), but in animals treated with COL.HAP-91 complete regeneration was not observed.

Membrana amniótica canina utilizada como bandagem em úlcera superficial de córnea de coelhos - aspectos clínicos

Twenty-eight rabbits were submitted to superficial keratectomy. The treated group consisted of 14 animals received canine amniotic membrane as a bandage, sutured in a way that its epithelial surface was in contact with the corneal surface. The control group did not receive any treatment. The animals were submitted to clinical evaluations 24 hours after surgery, at each two-day interval during one week and at each four-day interval during 180 days. The amniotic membranes were evaluated as a bandage comparing the time needed for corneal epithelization in the treated and non-treated groups and determining the period necessary for the cornea to become completely transparent. The corneal opacity was present during the entire time of observation. The treated animals presented more opaque cornea in the early period of regeneration, with neovascularization and more pain and discomfort than the animals from control group, showing a delayed epithelization.

Osteointegração da hidroxiapatita sintética no processo alveolar da mandíbula de cães: aspectos histológicos

The synthetic hydroxyapatite was evaluated as bone substitute in the regeneration of the alveolar process. Twenty-eight healthy adult dogs weighing from 10 to 15kg were divided into two groups. Defects around 6 x 5mm were provoked on the vestibular surface of the alveolar process until reaching the root of the fourth right mandibular premolar tooth. In one group the defect was totally infilled with synthetic hydroxyapatite, whereas the other untreated one was used as control. On days 8, 15, 21, 42, 60, 90 and 120, bone fragments were collected for the histological analysis under optical microscopy. The following results were observed: both bone and vascular growth inside the hydroxyapatite pores, intense osteoblast proliferations and neovascularization at the presence of the implant. The biocompatibility of the hydroxyapatite allowed its integration with the alveolar process by direct formation of a lamellar bone. The bone neoformation occurred as the hydroxyapatite was degraded.

Composição do líquido sinovial de cães com ruptura do ligamento cruzado cranial

The characteristics of the synovial fluid of both stifle joints from dogs with unilateral cranial cruciate ligament rupture were studied in six adult dogs. The macroscopic parameters observed were color, volume, viscosity, turbidity, and coagulation. In addition, mucin tests were performed. The microscopic parameters were global cell counting and differential cell counting. Two animals presented normal viscosity and in the others the viscosity was reduced. The result of the mucin test was normal in all animals and there was no coagulation of the fluid when in contact with the air. The differential cell counting was maintained within regular standards cited in the literature. Therefore, in the cases of cranial cruciate ligament rupture, the synovial fluid of the stifle joint can stay without any macroscopic change. Although the global and relative cell composition of the affected joint synovial fluid were kept within regular standards according to the literature, they were consistently higher than that of the normal joint.

Guided tissue regeneration using rigid absorbable membranes in the dog model of chronic furcation defect

Abstract Objective. Absorbable membranes are used to promote the regeneration of periodontal defects by Guided Tissue Regeneration (GTR). However, their collapse into the defect is commonly reported, impairing regeneration. Therefore, absorbable but rigid membranes aiming at preventing such collapse were developed and analyzed in periodontal regeneration. Materials and methods. Membranes were analyzed in class II furcation defects in dogs; procedures included periodontal disease induction, prophylaxis and GTR (treated groups) or open flap debridement alone (control group). For GTR, the membranes were made of either 25% hydroxyapatite (HA) in polyhydroxybutyrate matrix (PHB) or 35% HA in PHB. Animals were clinically evaluated for gingival recession, clinical attachment level (CAL) and biopsies were collected at 60 and 120 days. Bone volume, trabeculae number, trabecular thickness and trabecular separation were quantified by micro-computed tomography, followed by histology. Results. Membrane exposure was observed in both treated groups (25 and 35% HAP) from the 8th day after surgery, continuously progressing until 120 days. Mean CAL for all groups remained above normal values for dogs. Bone volumetric values were not significantly different. Partial formation of bone, cementum and periodontal ligament was observed in treated groups. An inflammatory infiltrate was observed in the dense connective tissue that partially filled the center of the treated defects with active osteoclasts on bone surface. Conclusion. Although partial regeneration of the defect was observed, it was limited by wound contamination. Consequently, rigid absorbable membranes made of HA and PHB failed to improve the regeneration of class II furcation defects in dogs.

Processo de reparação de lesões da córnea e a membrana amniótica na oftalmologia

The events included in the process of repair of corneal damage occur simultaneously and involve proliferation, migration, differentiation, cell apoptosis and intercellular communication. Several soluble factors, mesenchymal matrix proteins, proteoglycans, proteolytic enzymes and some cell types are covered in this review, which explains the processes of repair of corneal wounds, either superficial or penetrating. The amniotic membrane, used in ophthalmic surgery, was studied because of the contribution of its functions to the repair process. However, these functions may be lost when the amniotic membrane is subjected to conservation. Therefore, it is important to understand the repair process of lesions involving or not the entire thickness of the cornea, and choose the best use of the amniotic membrane, when it is indicated for the treatment of these lesions.