RESUMO

La osteoporosis se caracteriza por una masa ósea baja con deterioro de la microarquitectura del tejido que conduce a la fragilidad, lo que aumenta el riesgo de fracturas. Después de la menopausia, la deficiencia de estrógenos aumenta la exposición del tejido al ligan- do RANK, lo que resulta en un aumento de la reabsorción y pérdida ósea, que pueden provocar osteoporosis. (1) Los bifosfonatos y el denosumab son utilizados para el tratamiento de la osteoporosis debido a su capacidad anticatabólica, que reducen la remodelación previniendo la pérdida de masa ósea, disminuyendo la probabilidad de fracturas y aumentando la densidad mineral del tejido. (2) La osteonecrosis de los maxilares asociadas a drogas antirresortivas es una situación que se presenta en pacientes que consumen de manera crónica antirresortivos para el tratamiento de enfermedades como: osteoporosis, osteogénesis imperfecta, enfermedad de Paget, displasia fi- brosa, hipercalcemia maligna asociada a tratamiento oncológico (AU)

Osteoporosis is characterized by low bone mass with deterioration of the tissue microarchitec- ture leading to fragility, which increases the risk of fractures. After menopause, estrogen deficiency increases tissue exposure to the RANK ligand, resulting in increased bone loss and resorption, which can lead to osteoporosis. (1) Bisphosphonates and denosumab are used for the treatment in low concentration, due to their anticatabolic capacity, which reduce remodeling, preventing loss of bone mass and fractures besides, antiresorptives drugs increase the mineral density of the tissue. (2) Osteonecrosis of the jaw associated with antiresorptives drugs occurs in patients whose chro- nically consume these drugs for the treatment of diseases such as: osteoporosis, imperfect osteogenesis, Paget's disease, fibrous dysplasia, malignant hypercalcemia associated with oncological treatment (AU)

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BACKGROUND: Telmisartan is an antihypertensive angiotensin II receptor blocker. This antihypertensive shows antiinflammatory activity. PURPOSE: In this study, the antiinflammatory activity of telmisartan was tested in an acetic acid (10%) model of ulcerative colitis (UC) in rats. METHODS: Rats were given 1, 3, and 5mg/kg/day of telmisartan orally for 3 days before induction of UC. The same doses were also administered 2 and 24h after induction. Rats from the non-colitis and non-treated colitis groups were administered vehicle (saline, 5 ml/kg) orally and another group received sulfasalazine (50mg/kg/day). Colons tissue was analyzed by macroscopic, by histopathology, by the immunohistochemical examination of RANKL/RANK pathway; by ELISA analysis of the levels of IL-10, TNF-α, myeloperoxidase (MPO) and malonaldehyde (MDA). RESULTS: Telmisartan at 5mg/kg reduced levels of MPO, MDA, TNF-α and increased of IL-10 (p<0.05). Additionally, telmisartan reduced macroscopic damage, number of ulcers, and inflammatory and histopathological processes such as neutrophil infiltration, changes in cytoarchitecture, and necrosis. Immunohistochemistry revealed down-regulation of nuclear factor-kappaB receptor/nuclear factor-kappaB ligand (RANK/RANKL) in groups treated with sulfasalazine or telmisartan. CONCLUSION: Telmisartan exerts beneficial effects in an acetic acid model of colitis in rats. These effects may be due to accelerated termination of the acute inflammatory phase, indicated by decreased TNF-α and increased production of IL-10 and low expression of RANKL and RANK.

Assuntos

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The aim of this study was to evaluate the resorption process during the repair of autogenous bone grafts with or without coverage by an expanded polytetrafluoroethylene (e-PTFE) membrane in female rats with estrogen deficiency using the immunohistochemical technique. Eighty female rats were randomly divided into two groups (OVX and SHAM). The 40 female rats in the OVX group were subjected to ovariectomy, and the 40 female rats in the SHAM group were subjected to simulated ovariectomy. The two groups were further divided in subgroup E, which was subjected to surgery for placement of autogenous bone graft (ABG), and subgroup ME, in which the ABG was covered with an e-PTFE membrane. The animals were killed at 0, 7, 21, 45 and 60 days. The specimens were analyzed using immunohistochemistry for the bone resorption markers RANK, RANK-L and Osteoprotegerin (OPG). A higher remodeling rate was observed at 7 and 21 days after the autogenous bone grafts, when the markers were more intensely expressed. At the final time point, the specimens presented similar characteristics to those observed at the initial time point. The expression of immunohistochemical markers was not altered by the estrogen deficiency. The presence of the e-PTFE membrane delayed the bone resorption process, influencing the immunohistochemical expression of markers.

Assuntos

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The MSX2 homeoprotein is implicated in all aspects of craniofacial skeletal development. During postnatal growth, MSX2 is expressed in all cells involved in mineralized tissue formation and plays a role in their differentiation and function. Msx2 null (Msx2 (-/-)) mice display complex craniofacial skeleton abnormalities with bone and tooth defects. A moderate form osteopetrotic phenotype is observed, along with decreased expression of RANKL (TNFSF11), the main osteoclast-differentiating factor. In order to elucidate the role of such an osteopetrosis in the Msx2 (-/-) mouse dental phenotype, a bone resorption rescue was performed by mating Msx2 (-/-) mice with a transgenic mouse line overexpressing Rank (Tnfrsf11a). Msx2 (-/-) Rank(Tg) mice had significant improvement in the molar phenotype, while incisor epithelium defects were exacerbated in the enamel area, with formation of massive osteolytic tumors. Although compensation for RANKL loss of function could have potential as a therapy for osteopetrosis, but in Msx2 (-/-) mice, this approach via RANK overexpression in monocyte-derived lineages, amplified latent epithelial tumor development in the peculiar continuously growing incisor.

Assuntos

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The increase bone turnover is the most important fact at the physiopathology of postmenopausal osteoporosis. At the molecular level it is the increase of the RANK-L the principal mediator who allows the osteoclasts formation, survival and development of them. Multiple models have been in use in preclinical investigations for evaluating the effects of the inhibition of the RANKL, between which it is included on OPG's over-expression in mice and transgenic mouse and by means of other models that include the treatment with recombinant OPG. The results of these studies show that RANKL's inhibition improves the DMO as well as the geometry and resistance of the bone. Several references clinical trials have investigated the potential of denosumab as antiresorptive drug for the prevention and treatment of bone disease. It is a monoclonal antibody, the first fully human, which were recently published results of randomized clinical trials to eight years for increasing BMD in different locations and five years for the prevention of vertebral and hip fractures. We review the fundamentals of the mechanism of inhibition of RANK-L and the results of several clinical trials of Denosumab.

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OBJECTIVES: Little information is available on the molecular events that occur during graft incorporation over time. The calvarial bone (Cb) grafts have been reported to produce greater responses compared with other donor regions in maxillofacial reconstructions, but the scientific evidences for this are still lacking. The objectives of this study are (1) to study the morphological pattern of Cb onlay bone grafts and compare them with the biological events through immunohistochemical responses and (2) to establish the effects of perforations in maintaining the volume and bone density of the receptor bed. MATERIAL AND METHODS: Sixty New Zealand White rabbits were submitted to Cb onlay bone grafts on the mandible. In 30 rabbits, the receptor bed was perforated (perforated group), while for the remaining animals the bed was kept intact (non-perforated group). Six animals from each group were sacrificed at 5, 7, 10, 20 and 60 days after surgery. Histological sections from the grafted area were prepared for immunohistochemical and histological analyses. Immuno-labeling was found for proteins Osteoprotegerin (OPG), receptor activator of nuclear factor-kappabeta ligand (RANKL), alkaline phosphatase (ALP), osteopontin (OPN), vascular endothelial growth factor (VEGF), tartrate-resistant acid phosphatase (TRAP), Type I collagen (COL I) and osteocalcin (OC). The tomography examination [computerized tomography (CT) scan] was conducted just after surgery and at the sacrifice. RESULTS: The histological findings revealed that the perforations contributed to higher bone deposition during the initial stages at the graft-receptor bed interface, accelerating the graft incorporation process. The results of the CT scan showed lower resorption for the perforated group (P

Assuntos