Effect of exercise training and chronic caffeine intake on bone tissue of young rats

Foram avaliados os efeitos da ingestão crônica de cafeína e exercício de natação sobre o tecido ósseo. Ratos Wistar jovens (n = 32) alocados em quatro grupos: sedentário controle (SCO), sedentário + cafeína (SCAF), treinados (TCO) e treinados + cafeína (TCAF), receberam 1 mg/ml de cafeína em água durante 30 dias (SCAF e TCAF) e foram submetidos a 21 dias de natação em intensidade moderada (TCO e TCAF). A tíbia esquerda foi submetida a ensaio biomecânico para determinação do coeficiente de rigidez, limite de elasticidade e carga máxima. A área de tecido ósseo primário e espessura do disco epifisário foram avaliadas no fêmur. Não foram observadas alterações nas propriedades biomecânicas e na deposição de tecido ósseo primário. O grupo SCAF apresentou maior espessura no disco epifisário distal. Os resultados sugerem que o treinamento moderado de natação e a ingestão de cafeína não provocaram alterações morfológicas e biomecânicas do tecido ósseo.Se evaluaram los efectos del consumo crónico de cafeína y la natación em el hueso. Ratas Wistar jóvenes (n=32) divididas en cuatro grupos: sedentarios control (SCO), sedentarios + cafeína (SCAF), entrenados (TCO) y entrenados + cafeína (TCAF), recibieron 1 mg/ml de cafeína en agua durante 30 días (SCAF e TCAF) e fueron sometidos 21 días de la natación moderada. La tibia izquierda se sometió a una prueba biomecánica para determinar la coeficiente de la rigidez, el limite de elasticidad y el punto de carga máxima. El area de hueso imaturo e de la zona de la placa de crescimiento proximal e distal se analizó em el fêmur. No se observaron cambios en las propiedades biomecánicas y el déposition de hueso inmaturo. Animales SCAF tenía más grueso de la placa de crescimiento distal. Los resultados sugieren que entrenamento moderalado de la natación y el cosumo crônico de cafeína no cambió la morfología y las propiedades biomecánicas del hueso.Effects of swimming training and chronic caffeine intake on bone tissue of young rats were investigated. Young Wistar rats were allocated into 4 groups: sedentary control (SCO), sedentary + caffeine (SCAF), trained (TCO) and trained + caffeine (TCAF); they received 1 mg/ml of caffeine diluted in water for 30 days (SCAF and TCAF) and were submitted to swimming training of moderate intensity for 21 days (TCO and TCAF). The left tibia was subjected to the biomechanical test for determination of the coefficient of stiffness, yield and maximum load. The immature bone tissue area and thickness of growth plates were evaluated in the femur. No changes were observed in biomechanical properties and the area occupied by immature bone tissue. However, SCAF group presented greater thickness in distal growth plate. The results suggest that the moderate intensity swimming training and caffeine consumption were not able to promote changes in morphology and biomechanical properties of bone tissue

Clinical, biomechanical and histological study on oophorectomy induced menopause

Objective:To investigate the clinical implications as well as biomechanical and histological changes and in bone tissue induced by ovariectomy in 64 rats.Methods:The rats were divided into two groups: bilateral oophorectomy or placebo, and subdivided into four subgroups, according to time postoperatively: three, six, nine and 12 months. The weight of the animals at the time of sacrifice was taken into consideration. The biomechanical study was performed on the right tibia, to the maximum load and stiffness coefficient. For the histological study we calculated the trabecular bone of the left tibia. Statistical analysis of body weight and mechanical properties was performed by variance analysis, complemented with Tukey's multiple comparison tests; and trabecular area, the non-parametric variance analysis.Results:Ovariectomy-induced menopause caused an increase in body weight, reduction of diaphyseal bone resistance at six months of hormone deprivation, but this effect is equalized over time by aging; bone stiffness was smaller in the ovariectomized group and reduction of bone mass occurred.Conclusion:The removal of the ovaries produced systemic alterations, characterized by metabolic changes that caused weight gain and changes in bone tissue, associated with alteration of the mechanical profile and reduced bone mass. Level of Evidence I, Clinical Study.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Estudo mecânico da estabilidade dorsal da osteossíntese intramedular associada à fixação externa (método de Ulson)

OBJETIVO: Avaliar o método de Ulson de fixação intramedular associado à fixação externa variando a altura do travamento externo dos fios de Kirschner e sem fixação externa. MÉTODO: Foram utilizadas 18 tíbias de porcos, sendo realizada osteotomia transversal na região da tuberosidade e introduzidos dois fios de Kirschner intramedulares em cada peça, em três diferentes padrões de montagem: grupo I - travamento com minifixador externo com 3,0cm de altura; grupo II - travamento com 4,5cm de altura; grupo III: sem travamento externo. Realizaram-se ensaios mecânicos de cisalhamento, obtendo-se: carga máxima, limite de proporcionalidade e coeficiente de rigidez. RESULTADOS: Não foram encontradas diferenças significativas de carga máxima e limite de proporcionalidade entre os grupos; o grupo II apresentou maior coeficiente de rigidez. CONCLUSÃO: A altura do travamento dos fios de Kirschner no método de Ulson, dentro dos limites avaliados, não prejudicou a estabilidade do sistema de fixação da fratura.OBJECTIVE: To evaluate the Ulson intramedullary fixation method, with external fixation in which the level of the external locking of the Kirschner wires is varied, and without external fixation. METHODS: Eighteen porcine tibias were used. Transverse osteotomy was performed in the region of the tuberosity, and two intramedullary Kirschner wires were inserted into each specimen, using three different assembly patterns: Group I: locking with external minifixator at a height of 3.0 cm; Group II: locking at a height of 4.5 cm; Group III: without external locking. Mechanical shear tests were then conducted, to determine the maximum load, proportionality limit and coefficient of rigidity. RESULTS: There were no significant differences in maximum load or proportionality limit between the groups. The coefficient of rigidity was higher in Group II. CONCLUSION: The locking height for the Kirschner wires in Ulson's method, within the limits evaluated, did not harm the stability of the fracture fixation system

O Zoledronato no tratamento da osteoporose umeral em ratas: estudo prospectivo e randomizado

OBJETIVO: Investigar as repercussões clínicas, biomecânicas e histomorfométricas do zoledronato no tratamento da osteoporose umeral em ratas osteoporóticas. MÉTODOS: Analisou-se, prospectivamente, 40 ratas (Rattus novergicus albinus). Com 60 dias de vida, foram aleatorizadas em dois grupos de acordo com o procedimento cirúrgico: ooforectomia bilateral (O) (n=20) e pseudo-cirurgia (P) (n=20). Após trinta dias, os animais foram novamente randomizados, de acordo com a administração de 0,1mg/kg de zoledronato (AZ) ou água destilada (AD): OAZ (n=10), OAD (n=10), PAZ (n=10) e PAD (n=10). Após doze meses, os animais foram eutanasiados e seus úmeros retirados. Clinicamente considerou-se o peso dos animais; biomecanicamente foram realizados ensaios compressivos e histomorfometricamente foi determinada a área trabecular óssea. RESULTADOS: Os grupos O tiveram um aumento de peso maior que os grupos P (p=0,005). Os grupos com zoledronato suportaram maior carga máxima que os grupos com água destilada (p=0,02). Nos grupos com zoledronato verificou-se o aumento da área trabecular óssea quando comparados aos grupos com água destilada (p=0,001). Houve correlação positiva entre a área trabecular e a carga máxima (p=0,04; r=0,95). CONCLUSÃO: O zoledronato não influiu no peso dos animais. Os resultados mostraram o aumento da resistência óssea umeral e da área trabecular óssea.OBJECTIVE: To evaluate the clinical, biomechanical and histomorphometric effects of zoledronate in the humerus of ovariectomized rats. METHODS: Forty female rats (Rattus norvegicus albinus) were prospectively evaluated. Within 60 days, animals were randomized into two groups: ovariectomy (O) (n=20) or sham surgery (P) (n=20). Within 90 days, groups O and P were subdivided into four groups, according to the administration of zoledronate (AZ) or deionized water (AD): OAZ (n=10), OAD (n=10), PAZ (n=10) and PAD (n=10). Within 15 months, animals were sacrificed. Body weight was used for clinical study, axial compression tests for the biomechanical study and cancellous bone area for the histomorphometric study. RESULTS: Ovariectomized groups had greater body weight gain than the sham groups (p=0.005). Zoledronate groups had greater body weight gain compared to the deionized water groups (p=0.68). Maximum load support was greater in the groups treated with zoledronate (p=0.02). An increase in cancellous bone area was noted in the groups treated with zoledronate (p=0.001). A positive correlation was shown in the evaluation of cancellous area and maximum load (p=0.04; r=0.95). CONCLUSIONS: Zoledronate had no effect on animals' body weight. Groups treated with zoledronate had increased maximum load support and cancellous bone area

Efeito tardio e imediato da sutura em tendão extrassinovial íntegro: estudo biomecânico em ratos

OBJETIVO: O objetivo do estudo foi avaliar o efeito, nas propriedades mecânicas, do arranjo de reparo com material de sutura, no tendão calcâneo de rato, na ausência de processo de cicatrização. MÉTODO: Foram utilizados 12 ratos machos da linhagem Wistar. Os animais foram submetidos à colocação de ponto de sutura tipo Kessler modificado no tendão calcâneo. Os sacrifícios foram realizados nos períodos imediato e com seis semanas de pós-operatório. As propriedades mecânicas estudadas foram: carga máxima, tensão na carga máxima e módulo de elasticidade. O tendão contralateral foi usado como controle. RESULTADOS: A análise estatística indicou que, em relação aos períodos estudados, os valores das propriedades mecânicas não apresentaram diferenças significativas. em relação ao controle, isto é, tendão contralateral sem sutura, os resultados demonstram que, com seis semanas de pós-operatório, houve queda dos valores do módulo de elasticidade, enquanto a carga máxima e a tensão na carga máxima não apresentaram variações significativas. CONCLUSÃO: A colocação de material de sutura em tendão extrassinovial não lesado provocou queda do módulo de elasticidade, porém não interferiu na carga máxima e na tensão na carga máxima após seis semanas de pós-operatório.OBJECTIVE: The aim of this study was to evaluate the effects on the mechanical properties of rats' calcaneus tendons, of repair arrangements using suture material in the absence of any healing process. METHOD: Twelve male Wistar rats were used. They were subjected to placement of a modified Kessler suture stitch in the calcaneus tendon. The sacrifices were performed immediately after and six weeks after the operation. The mechanical properties studied were maximum load, tension in the maximum load and module of elasticity. The contralateral tendon was used as a control. RESULTS: The statistical analysis showed that for the times studied, the values for mechanical properties did not present any significant differences. In relation to the control, i.e. the contralateral tendon without a suture, the results demonstrated that, six weeks after the operation, the values for the modulus of elasticity were lower, whereas there were no significant variations in maximum load or tension at maximum load. CONCLUSION: Placement of suture material on an extrasynovial tendon without lesions decreased the modulus of elasticity, but it did not interfere with the maximum load or tension at maximum load, six weeks after the operation

Beneficial effects of diclofenac therapy on serum lipids, oxidized low-density lipoprotein and antioxidant defenses in rats

To study the effects of diclofenac, a nonselective nonsteroidal anti-inflammatory drug (NSAID), on lipid profile, oxidized low-density-lipoprotein (Ox-LDL), serum antioxidant defenses and markers of oxidative stress, male Wistar rats were divided into two groups (n = 10): (C) receiving intramuscularly a single daily dose of saline (NaCl 0.9%), and (AI) receiving intramuscularly a single daily dose of 10 mg/kg diclofenac sodium (C14H10C12NNaO2). After 28 days diclofenac-treated rats had lower Ox-LDL, apoprotein B (apo-B), apo-B/LDL-cholesterol and lipid hydroperoxide than C. Total antioxidant substances and superoxide dismutase were increased in diclofenac-treated rats, while no significant changes were observed in catalase, glutathione peroxidase and nitric oxide. A perincubation test done to examine the possibility of mechanism-based activation showed that diclofenac had no effect on maximal superoxide dismutase velocity, but significantly reduced the Michaelis-Menten (K-M) constant, indicating that diclofenac induced SOD activation increasing substrate linkage affinity to the enzyme-catalytic site. In conclusion, diclofenac had beneficial effects decreasing Ox-LDL and improving antioxidant defense. It appears that the application of this agent may be feasible and beneficial for serum antioxidant protection, which certainly would bring new insights on dyslipidemia control. (C) 2008 Elsevier B.V. All rights reserved