EFFECT OF COPPER ON THE SECRETION OF HUMAN GROWTH-HORMONE

UNIV SAO PAULO,FAC CIENCIAS FARMACEUT RIBEIRAO PRETO,DEPT FIS & QUIM,BR-14049 RIBEIRAO PRETO,SP,BRAZILESCOLA PAULISTA MED,FAC MED,DEPT CLIN MED,BR-04034 SAO PAULO,SP,BRAZILUNIV SAO PAULO,FAC RIBEIRAO PRETO,DEPT FISIOL,BR-14049 RIBEIRAO PERTO,SP,BRAZILESCOLA PAULISTA MED,FAC MED,DEPT CLIN MED,BR-04034 SAO PAULO,SP,BRAZILWeb of Scienc

Mechanical vibration preserves bone structure in rats treated with glucocorticoids

Glucocorticoids are an important cause of secondary osteoporosis in humans, which decreases bone quality and leads to fractures. Mechanical stimulation in the form of low-intensity and high-frequency vibration seems to be able to prevent bone loss and to stimulate bone formation. The objective of this study was to evaluate the effects of mechanical vibration on bone structure in rats treated with glucocorticoids. Thirty 3-month-old adult male Wistar rats were randomized to three groups: control (C), glucocorticoid (G), and glucocorticoid with vibration (CV). The G and GV groups received 3.5 mg/kg/day of methylprednisolone 5 days/week for a duration of 9 weeks, and the C group received vehicle (saline solution) during the same period. The CV group was vibrated on a special platform for 30 min per day, 5 days per week during the experiment. The platform was set to provide a vertical acceleration of 1 G and a frequency of 60 Hz. Skeletal bone mass was evaluated by total body densitometry (DXA). Fracture load threshold, undecalcified bone histomorphometry, and bone volume were measured in tibias. Glucocorticoids induced a significantly lower weight gain (-9.7%) and reduced the bone mineral content (-9.2%) and trabecular number (-41.8%) and increased the trabecular spacing (+98.0%) in the G group, when compared to the control (C). Vibration (CV) was able to significantly preserve (29.2%) of the trabecular number and decrease the trabecular spacing (+ 26.6%) compared to the G group, although these parameters did not reach C group values. The fracture load threshold was not different between groups, but vibration significantly augmented the bone volume of the tibia by 21.4% in the CV group compared to the C group. Our study demonstrated that low-intensity and high-frequency mechanical vibration was able to partially inhibit the deleterious consequences of glucocorticoids on bone structure in rats. (C) 2010 Elsevier Inc. All rights reserved.CAPES Coordenacao de Pessoal de Ensino Superio

Low-level laser therapy, at 60 J/cm(2) associated with a Biosilicate (R) increase in bone deposition and indentation biomechanical properties of callus in osteopenic rats

We investigate the effects of a novel bioactive material (Biosilicate (R)) and low-level laser therapy (LLLT), at 60 J/cm(2), on bone-fracture consolidation in osteoporotic rats. Forty female Wistar rats are submitted to the ovariectomy, to induce osteopenia. Eight weeks after the ovariectomy, the animals are randomly divided into four groups, with 10 animals each: bone defect control group; bone defect filled with Biosilicate group; bone defect irradiated with laser at 60 J/cm(2) group; bone defect filled with Biosilicate and irradiated with LLLT, at 60 J/cm(2) group. Laser irradiation is initiated immediately after surgery and performed every 48 h for 14 days. Histopathological analysis points out that bone defects are predominantly filled with the biomaterial in specimens treated with Biosilicate. in the 60-J/cm(2) laser plus Biosilicate group, the biomaterial fills all bone defects, which also contained woven bone and granulation tissue. Also, the biomechanical properties are increased in the animals treated with Biosilicate associated to lasertherapy. Our results indicate that laser therapy improves bone repair process in contact with Biosilicate as a result of increasing bone formation as well as indentation biomechanical properties. (C) 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.3598847]Univ Fed Sao Carlos, Dept Physiotherapy, BR-13600970 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biosci, BR-11050240 São Paulo, BrazilUniv Fed Sao Carlos, Dept Biol, BR-13600970 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Physiotherapy, BR-11050240 São Paulo, BrazilUniv Fed Sao Carlos, Dept Stat, BR-13565208 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biosci, BR-11050240 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Physiotherapy, BR-11050240 São Paulo, BrazilWeb of Scienc