Biomechanical evaluation in osteoporosis: ovariectomized rat model.

The aim of our study was to investigate the effects of ovariectomy on rat femur biomechanical parameters. Bone mineral density (BMD) and histological investigation were also evaluated. Fourteen female Sprague-Dawley rats (seven ovariectomized, seven control) were used. BMD was measured by dual-energy X-ray absorbsiometry. Bone biomechanical parameters were measured in femoral midshaft with tensile test using a biomaterial testing machine and maximum load, stiffness, energy absorption capacity (structural properties), ultimate stress, ultimate strain, and elastic modulus (material properties) were calculated. Diaphyseal cortical bone thickness was measured by using histological method. The ovariectomized (OVX) rat femur's BMD was 14% lower than control rats (p=0.006). Mean maximum load was 55% less than the control group's (p=0.0001). Stiffness was 72% less in OVX rats (p=0.05). Femurs of rats with OVX had 32% less absorbed energy than controls (p=0.09). From the stress-strain curve ultimate stress, ultimate strain and elastic modulus was calculated. Elastic modulus was 53% less than controls (p=0.05). Ultimate stress decreased 21% in OVX rats (p=0.097). Ultimate strain was 25% less than controls in OVX rats. Cortical thickness was significantly decreased in OVX rats than in controls (p<0.05). In conclusion, femur biomechanical parameters are decreased in osteoporosis.

Is there a role of free oxygen radicals in primary male osteoporosis?

OBJECTIVE: There is not enough evidence about the relationship between free radicals and male osteoporosis. In this study we investigated the role of free oxygen radicals and antioxidants on male osteoporosis in 31 male patients with primary osteoporosis and 21 subjects as controls. METHODS: Bone mineral densities (BMD) of the lumbar and femoral neck region were evaluated using dual energy X-ray absorbsiometry. Serum malondialdehyde (MDA) and nitric oxide (NO) levels and superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities were measured by analytical methods. In addition, serum osteocalcine and C telopeptide levels were determined to evaluate bone turnover MDA and NO levels and SOD activity were significantly increased (p < 0.05) in osteoporotic males. RESULTS: There was a negative correlation between SOD and lumbar BMD levels (r= -0.328; p = 0.021). The same trend was observed between NO and lumbar BMD (r = -0.473; p = 0.001) and femoral neck BMD values (r = -0.540; p = 0.000). There was no significant correlation between free radical levels and bone turnover markers. CONCLUSION: The data indicate an increase in free oxygen radical levels. As a result, antioxidant defenses would compromise in primary male osteoporotic patients. Therefore, it may be suggested that oxidative stress plays an important role in the pathophysiology of primary male osteoporosis.

Plasma catalase activity and malondialdehyde level in patients with cataract.

PURPOSE: Oxidative mechanisms play a major role in the aetiology and pathogenesis of cataract, especially in age-related cataract. Our study aims to investigate systemic oxidant and antioxidant markers in cataract patients. METHODS: The activity of erythrocyte catalase and the level of malondialdehyde in plasma were measured in 40 patients with cataract and 60 healthy control subjects. The malondialdehyde level, as an index of lipid peroxidation, was determined by thiobarbitüric acid reaction according to Yagi. The determination of catalase activity was measured by a method that was defined by Beutler. Catalase enzyme activity and malondialdehyde level were evaluated to find out whether there was a significant difference in these variables. Analysis of variance was used by forming a general linear model that takes age and gender as the covariate. RESULTS: CAT activity was found to be 13 920.2 +/- 847.9 U/l in cataract patients and 16 061.3 +/- 1126.6 U/l in control subjects. CAT activity in cataract patients was significantly lower than the control subjects (P = 0.008). Plasma MDA level is significantly higher in patients with cataract 4.47 +/- 0.35 nmol/ml compared to the control subjects 2.94 +/- 0.26 nmol/ml (P = 0.0001). There was no significant difference between different cataract subgroups when erythrocyte CAT activities and plasma MDA levels were compared (P = 0.322, 0.062). CONCLUSION: This study shows that oxidant/antioxidant balances alter in the presence of cataract.