Observation Of The Bone Matrix Structure Of Intact And Regenerative Zones Of Tibias By Atomic Force Microscopy

The structure of bone matrix of rat tibia from an intact and regenerative zones of tibias was studied using atomic force spectroscopy. The young male adult rats (wistar) were used for the study with corporal masses between 250 and 300 g. A 1.5-mm-diam hole was drilled in one cortical tibia surface to provoke the injury and the healing course was monitored. Atomic force spectroscopic images were used at different magnifications to identify the time dependence of the osteoblast activity, measured by the increase in the area of neoformed primary bone and in the organization of the collagen fibers.19410421045Manolagas, S.C., (1998) Aging-Clinical Exp. Res., 10, p. 182Rodan, G.A., Martin, T.J., (2000) Science, 289, p. 1508Silver, I.A., Murrills, R.J., Etherington, D.J., (1998) Exp. Cell Res., 175, p. 266Rodan, G.A., (1997) Bone (N.Y.), 20, p. 1Sandmaier, B.M., Sorb, R., Kniley, J., Hardy, W., Black, M., Moseley, A., Deans, R., (1998) Blood, 92, p. 473Michaelsson, K., Baron, J.A., Farahmand, B.Y., Johenll, O., Magnusson, C., Persson, P.G., Persson, I., Ljunghall, S., (1998) Br. Med. J., 316, p. 1858Bonadio, J., Smiley, E., Patil, P., Goldstein, S., (1999) Nature Med., 5, p. 753Freitas, I.G.F., Baranauskas, V., Cruz-Höfling, M.A., (2000) Appl. Surf. Sci., 154-155, p. 548Binnig, G., Quate, C.F., Gerber, Ch., (1986) Phys. Rev. Lett., 56, p. 930Yang, J., Shao, Z., (1995) Micron, 26, p. 35Wickramasinghe, H.R., (2000) Acta Mater., 48, p. 347Baranauskas, V., Vidal, B.C., Parizotto, N.A., (1998) Appl. Biochem. Biotech., 69, p. 91Ducy, P., Schinke, T., Karsenty, G., (2000) Science, 289, p. 1501Teitelbaum, S.L., (2000) Science, 289, p. 150

Low-power Laser Irradiation Improves Histomorphometrical Parameters And Bone Matrix Organization During Tibia Wound Healing In Rats.

The influence of daily energy doses of 0.03, 0.3 and 0.9 J of He-Ne laser irradiation on the repair of surgically produced tibia damage was investigated in Wistar rats. Laser treatment was initiated 24 h after the trauma and continued daily for 7 or 14 days in two groups of nine rats (n=3 per laser dose and period). Two control groups (n=9 each) with injured tibiae were used. The course of healing was monitored using morphometrical analysis of the trabecular area. The organization of collagen fibers in the bone matrix and the histology of the tissue were evaluated using Picrosirius-polarization method and Masson's trichrome. After 7 days, there was a significant increase in the area of neoformed trabeculae in tibiae irradiated with 0.3 and 0.9 J compared to the controls. At a daily dose of 0.9 J (15 min of irradiation per day) the 7-day group showed a significant increase in trabecular bone growth compared to the 14-day group. However, the laser irradiation at the daily dose of 0.3 J produced no significant decrease in the trabecular area of the 14-day group compared to the 7-day group, but there was significant increase in the trabecular area of the 15-day controls compared to the 8-day controls. Irradiation increased the number of hypertrophic osteoclasts compared to non-irradiated injured tibiae (controls) on days 8 and 15. The Picrosirius-polarization method revealed bands of parallel collagen fibers (parallel-fibered bone) at the repair site of 14-day-irradiated tibiae, regardless of the dose. This organization improved when compared to 7-day-irradiated tibiae and control tibiae. These results show that low-level laser therapy stimulated the growth of the trabecular area and the concomitant invasion of osteoclasts during the first week, and hastened the organization of matrix collagen (parallel alignment of the fibers) in a second phase not seen in control, non-irradiated tibiae at the same period. The active osteoclasts that invaded the regenerating site were probably responsible for the decrease in trabecular area by the fourteenth day of irradiation.7081-

Laserterapia de baixa intensidade na expressão de colágeno após lesão muscular cirúrgica Low-level laser therapy in the expression of collagen after muscular surgical injury

A laserterapia é um procedimento utilizado em larga escala nas lesões musculoesqueléticas, devido as suas diversas propriedades, antiinflamatórias, cicatrizantes entre outras. Além disso, há tipos distintos de aparelhos de laser. Mesmo com os diversos modelos experimentais existentes na literatura, não há um consenso sobre a faixa de utilização, bem como o tipo de laser que promove melhor reparo no tecido muscular. Este estudo visa analisar os efeitos da laserterapia de baixa intensidade na expressão de colágeno após lesão muscular. Camundongos Swiss albinos (n=18) foram submetidos à lesão muscular cirúrgica e divididos em dois grupos, controle (C) e teste (T). Os animais foram submetidos a uma irradiação diária de 5 J/cm² pelos lasers AsGaAl 830 nm e AsGa 904 nm e, em diferentes tempos de sacrifício (7 e 14 dias). Os resultados não demonstraram diferença estatística significativa na expressão de colágeno em ambos os grupos analisados. Contudo, os dados apontam que a dose de 5 J/cm² do laser AsGa 904 nm promoveu maior deposição de fibras colágenas após 14 dias de tratamento, sugerindo que a terapia seja efetiva na síntese de colágeno. Outros estudos experimentais, em humanos, devem ser propostos para maiores inferências sobre os resultados do laser no tratamento da lesão muscular.<br>The laser therapy is a procedure utilized at long scale in the musculoskeletal injuries, due its anti-inflammatory and reparatory proprieties and others. Besides, there are differents types of laser equipments. Despites with the many experimental models at literature, there is no consensus about the range of application as well as the type of laser that promove of the best repair in muscular tissue. The aim of this study is to analyze the effects of the low level laser therapy in the expression of collagen after muscular injury. Mice Swiss albinos (n=18) were subjected to the muscular surgical injury and separated in two groups, control (C) and test (T). The animals were submitted a daily radiation of 5 J/cm² for the lasers AsGaAl 830 nm and AsGa 904 nm and, in different times of sacrifice (7 and 14 days). The results didn't demonstrate significant statistical difference in the expression of collagen in both analyzed groups. However, the data appear that the dose of 5 J/cm² of the laser AsGa 904 nm promoted larger deposition of fibers collagens after 14 days of treatment, suggesting that the therapy is effective in the synthesis of collagen. Others studies will be proposed at humans to bigger inferences about the results of laser in the treatment muscular injury