Evaluation of Oxidative Stress Levels and Antioxidant Enzyme Activities in Burst Fractures

BACKGROUND Spinal burst fractures are pathologies that occur in spinal injuries and cause significant mortality and morbidity as a result. Burst fractures in spinal cord injuries can result in rapid and significant oxidative stress. In addition to the primary injury in severe spinal cord injuries, subsequent secondary lesions are mainly due to inflammatory cascade activation and excessive production of free radicals. This study evaluated oxidative stress and antioxidant enzyme levels in burst fractures. MATERIAL AND METHODS Twenty patients with burst fractures were diagnosed and underwent surgery and 20 healthy control subjects were included in the study. Neurological status was evaluated using the American Spine Injury Association Impairment Scale (ASIA) before and after surgery. Neurological function was scored as ASIA A: complete deficits, ASIA B-D: incomplete deficits, and ASIA E: neurologically intact. Spectrophotometry was performed to measure malondialdehyde (MDA) and low glutathione (GSH), glutathione peroxidase (GPx) levels, which represent lipid peroxide content. Evaluations were performed within 2 days after injury in the patients. RESULTS MDA levels were higher in the burst fracture group (p<0.001), whereas GSH and SOD activities were higher in the control group (both p<0.001). There was no statistically significant difference in GPx levels between the groups (p=0.482). CONCLUSIONS Oxidative stress appears to be related to burst fractures. Considering the importance of burst fractures in spinal cord injuries, a better understanding of these mechanisms may help in defining the role of oxidative stress after burst fractures. Prospective, randomized, controlled trials may reveal new therapeutic approaches that include antioxidants for explosive fractures focusing on oxidative stress.

Serum chitotriosidase in postmenopausal women with severe osteoporosis

Human chitotriosidase (Chit) increases during the osteoclast differentiation and their activity. We demonstrated that serum Chit was significantly higher in osteoporotic subjects than in healthy control ones and revealed a negative correlation between Chit and bone mineral density (BMD). This is the first study showing a correlation between Chit and severe postmenopausal osteoporosis.

INTRODUCTION

Mammalian chitinases exert important biological roles in the monocyte lineage and chronic inflammatory diseases. In particular, Chit seems to promote bone resorption in vitro. No in vivo studies have been performed to confirm this finding. We aim to evaluate Chit activity in postmenopausal women affected by severe osteoporosis.

METHODS

In this cross-sectional study, 91 postmenopausal women affected by osteoporosis and 61 with either osteopenia or normal BMD were screened. All subjects were assessed by dual-energy X-ray absorptiometry (DXA) and X-ray vertebral morphometry. Osteoporotic subjects were considered eligible if they were affected by at least one vertebral osteoporotic fracture (group A = 57 subjects). Osteopenic or healthy subjects were free from osteoporotic fractures (group B = 51 subjects). Enzymatic Chit and serum β-CrossLaps (CTX) were measured in the whole population.

RESULTS

Group A showed higher serum levels of beta-CTX compared to group B (0.40 ± 0.26 ng/mL vs 0.29 ± 0.2 ng/mL, p = 0.022). Chit was significantly higher in group A than in group B (1042 ± 613 nmol/mL/h vs 472 ± 313 nmol/mL/h, p < 0.001, respectively) even after adjustment for age (p < 0.001). Spearman correlation test revealed a negative correlation between Chit and BMD at each site (lumbar spine: r = -0.38, p = 0.001, femoral neck: r = -0.35, p = 0.001, total femur: r = -0.39, p < 0.001). Furthermore, a positive correlation between Chit and PTH was observed (r = 0.26, p = 0.013). No significant correlation was found between Chit and beta-CTX (r = 0.12, p = 0.229). After a multivariate analysis, a positive correlation between severe osteoporosis and Chit (p < 0.001), beta-CTX (p = 0.013), and age (p < 0.001) was observed.

CONCLUSION

This is the first clinical study showing a correlation between Chit and severe postmenopausal osteoporosis. Larger and prospective studies are needed to evaluate if Chit may be a promising clinical biomarker and/or therapeutic monitor in subjects with osteoporosis.

HSD11B1 polymorphisms predicted bone mineral density and fracture risk in postmenopausal women without a clinically apparent hypercortisolemia

INTRODUCTION

Endogenous glucocorticoid (GC) may participate in bone physiology, even in subjects with no glucocorticoid excess. 11beta-hydroxysteroid dehydrogenase type 1 (HSD11B1) is a primary regulator catalyzing the reduction of inactive cortisone to active cortisol. To elucidate genetic relevance of HSD11B1 variants to vertebral fracture and osteoporosis, we investigated the potential involvement of six HSD11B1 SNPs in postmenopausal women.

METHODS

All exons, their boundaries and the promoter region (approximately 1.5 kb) were directly sequenced in 24 individuals. Six polymorphisms were selected and genotyped in all study participants (n=1329). BMD was measured using dual-energy X-ray absorptiometry.

RESULTS

HSD11B1 +16374C>T and +27447G>C were associated with reduced vertebral fracture risk (p=0.016 and 0.032, respectively). Two of these (LD block2) in intron 5 (rs1000283 and rs932335) were significantly associated with bone mineral density (BMD) at the femoral neck (p=0.00005 and 0.0002, respectively). Specifically, HSD11B1 +16374C>T and +27447G>C polymorphisms were associated with higher BMD values of the femoral neck in multiple comparison (p=0.0002 and 0.0004, respectively) and Bonferroni corrected significance level (97% power). Consistent with these results, HSD11B1-ht21 and -ht22 comprising both SNPs also showed the evidence of association with BMD values of the femoral neck (p(domiant)=0.0002 and p(recessive)=0.00005, respectively).

CONCLUSION

Our results provide preliminary evidence supporting an association of HSD11B1 with osteoporosis in postmenopausal women. Also, these findings demonstrate that +16374C>T polymorphism may be useful genetic markers for bone metabolism.

Association of an aromatase TTTA repeat polymorphism with circulating estrogen, bone structure, and biochemistry in older women

Osteoporosis is a disease that is strongly genetically determined. Aromatase converts androgens to estradiol in postmenopausal women, therefore polymorphisms of the gene for this enzyme may be associated with bone mass and fracture. We investigated the association of the TTTA microsatellite polymorphism in intron 4 of the aromatase (CYP19) gene with bone mineral density (BMD) and fracture in 1,257 women aged 70 yr and greater. The data obtained were stratified based on the presence or absence of a [TTTA]n of 7 (A2), determined from a preliminary analysis of hip dual-energy X-ray absorptiometry BMD, which was present in 27% of the population. The presence of an A2 allele was associated with a higher free estradiol index (0.52 +/- 0.49, P = 0.049) compared with the absence of an A2 allele (0.47 +/- 0.45); higher BMD at all sites of the hip (3.4% total hip, 2.3% femoral neck, 3.6% intertrochanter, 4.1% trochanter) and the lumbar spine (12.7%); higher values for the calcaneal quantitative ultrasound parameters broadband ultrasound (1.3%), speed of sound (0.4%), and stiffness (3.7%); and higher peripheral quantitative computed tomography measures for total (3.4%), trabecular (3.3%), and cortical BMD (3.3%) and the derived stress strain index (SSI) parameters SSI polar (6.4%) and SSI x (6.8%) values. A lower deoxypryridinoline creatinine ratio was observed in subjects with an A2 allele (30.3 +/- 10.4 vs. 27.1 +/- 9.1, P = 0.03). The A2 allele was associated with a lower prevalence of vertebral fracture in subjects who were osteoporotic (odds ratio 0.27, confidence interval 0.09-0.79). Therefore, a common polymorphism of the aromatase gene, perhaps in linkage disequilibrium with a functionally significant CYP19 polymorphism, is associated with bone structure and bone turnover, either by local effects or by effects on circulating bioactive estrogen.

Comparison of bone and total alkaline phosphatase activity on bone turnover during menopause and in patients with established osteoporosis

OBJECTIVE

Recently, a bone alkaline phosphatase (AP) enzyme immunoassay (EIA) was developed for measurement of bone AP activity with a monoclonal antibody. We compared the clinical performance of bone AP (bAP) measured by EIA and total AP (tAP) to examine if bAP is preferable to tAP as a bone formation marker in the post-menopause and established osteoporosis.

DESIGN AND PATIENTS

Serum was obtained from 50 pre- and 93 post-menopausal healthy women, and 54 osteoporotic patients with vertebral fractures and 57 patients with hip fracture.

MEASUREMENTS

Total AP was measured spectrophotometrically with p-nitrophenyl phosphate as substrate. The intra- and inter-assay coefficients of variation were 0.7-1.8% and 0.6-1.1%, respectively. Bone AP activity (bAP) was measured by EIA kit, ALKPHASE-B (Metra Biosystems, Inc.) using a monoclonal antibody against human bone AP. The intra- and inter-assay CVs were 4.0-8.3% and 6.2-7.9%, respectively.

RESULTS

The percentage mean increase of bAP (54.9%) in post-menopausal subjects over premenopausal subjects was higher than that of tAP (40.1%). In age-matched comparison, % mean increases were 57.5% for bAP and 35.3% for tAP. Z-score for bAP in post-menopausal subjects was significantly higher than that for tAP. However, there was no significant difference in Z-scores between tAP and bAP in osteoporotic patients with vertebral fractures or with hip fracture. The correlation coefficient of bAP with age (r = 0.316) was similar to that of tAP with age (r = 0.319). In post-menopausal subjects, there was no difference in the concentrations of tAP nor bAP among the groups in whom times since the menopause was 0-9 years, 10-19 years and more than 20 years. Bone AP was highly correlated to tAP in the normal subjects, the patients and the total study group.

CONCLUSION

Preference can be given to bone AP by enzymatic immunoassay over total AP based on their clinical utility during the menopause; however, no preference can be given to bone AP over total AP in established osteoporosis.