RESUMO
OBJECTIVE: This study investigated the effects of low-level laser therapy (LLLT) and electrical stimulation (ES) on bone loss in spinal cord-injured rats. MATERIALS AND METHODS: Thirty-seven male Wistar rats were divided into four groups: standard control group (CG); spinal cord-injured control (SC); spinal cord-injured treated with laser (SCL; GaAlAs, 830 nm, CW, 30 mW/cm, 250 J/cm(2)); and spinal cord-injured treated with electrical field stimulation (SCE; 1.5 MHz, 1:4 duty cycles, 30 mW, 20 min). Biomechanical, densitometric, and morphometric analyses were performed. RESULTS: SC rats showed a significant decrease in bone mass, biomechanical properties, and morphometric parameters (versus CG). SCE rats showed significantly higher values of inner diameter and internal and external areas of tibia diaphyses; and the SCL group showed a trend toward the same result (versus SC). No increase was found in either mechanical or densitometric parameters. CONCLUSION: We conclude that the mentioned treatments were able to initiate a positive bone-tissue response, maybe through stimulation of osteoblasts, which was able to determine the observed morphometric modifications. However, the evoked tissue response could not determine either biomechanical or densitometric modifications.
Assuntos
Remodelação Óssea/fisiologia , Terapia por Estimulação Elétrica/métodos , Terapia com Luz de Baixa Intensidade/métodos , Osteoporose/prevenção & controle , Traumatismos da Medula Espinal/terapia , Análise de Variância , Animais , Fenômenos Biomecânicos , Densidade Óssea , Remodelação Óssea/efeitos da radiação , Osso e Ossos/patologia , Osso e Ossos/efeitos da radiação , Densitometria , Modelos Animais de Doenças , Imuno-Histoquímica , Masculino , Osteoporose/diagnóstico , Osteoporose/etiologia , Distribuição Aleatória , Ratos , Ratos Wistar , Valores de Referência , Traumatismos da Medula Espinal/complicaçõesRESUMO
OBJECTIVE: This study aimed to compare the consequences of low-level laser therapy (LLLT) and low-intensity pulsed ultrasound (LIPUS) on bone repair. BACKGROUND DATA: Many studies have assessed the effects of LLLT and LIPUS on bone repair, but a comparison of them is rare. METHODS: Male Wistar rats (n = 48) with tibial bone osteotomy were used. One group had the osteotomized limb treated with LLLT (GaAlAs laser, 780 nm, 30 mW, 112.5 J/cm(2)) and the second group with LIPUS (1.5 MHz, 30 mW/cm(2)), both for 12 sessions (five times per week); a third group was the control. After 20 days, rats were sacrificed and had their tibias submitted to a bending test or histomorphometric analysis. RESULTS: In the bending test, maximum load at failure of LLLT group was significantly higher (p < 0.05). Bone histomorphometry revealed a significant increase in osteoblast number and surface, and osteoid volume in the LLLT group, and a significant increase in eroded and osteoclast surfaces in the LIPUS group. CONCLUSION: LIPUS enhanced bone repair by promoting bone resorption in the osteotomy area, while LLLT accelerated this process through bone formation.
Assuntos
Consolidação da Fratura , Fraturas Ósseas/terapia , Terapia com Luz de Baixa Intensidade , Tíbia/lesões , Terapia por Ultrassom , Animais , Masculino , Osteotomia , Ratos , Ratos WistarRESUMO
We performed an endurance test on a textured diaphragm made of polyurethane (BioSpan, The Polymer Technology Group, San Francisco, CA, U.S.A.) to be used in the auxiliary total artificial heart (ATAH), an electromechanical device that can be totally implantable without removing the natural heart due to the device's reduced dimension. The objective of this endurance test was to predict whether this diaphragm would be capable of resisting in vivo tests with the ATAH implanted for fifteen days in calves. In this study, a mock loop system simulating the human circulatory system was used. The test protocol was elaborated to reproduce extreme physiological conditions. The technique to produce the textured diaphragms made of polyurethane is shown. The textured surface is used as basis to fix a layer of calf-skin gelatin. The technique used to make the diaphragm guaranteed a totally textured surface without cracking. The diaphragm demonstrated enough resistance to be used at the 15 day in vivo experiments.
Assuntos
Coração Artificial , Poliuretanos , Animais , Bovinos , Coração Auxiliar , Teste de Materiais , Miniaturização , Desenho de PróteseRESUMO
Corrosion processes due to contact with the physiological environment should be avoided or minimized in orthopedic implants. Four metallic substrates frequently used as biomaterials: pure Ti, Ti-6Al-4V alloy, ASTM F138 stainless steel, and Co-Cr-Mo alloy, were coated with TiN using the physical vapor deposition (PVD) technique. These coatings have been screened by polarization curves in physiological solutions. TiN prepared by PVD is efficient as coating for stainless steel. On titanium and alloy there are no benefits concerning the corrosion resistance compared to the bare Ti-materials. TiN coatings have been screened according to ISO 10993 standard tests for biocompatibility and exhibited no cytotoxicity, dermal irritation, or acute systemic toxicity response.