Effect of COX-2 inhibitors and non-steroidal anti-inflammatory drugs on a mouse fracture model.

A randomised, blinded, prospective animal study with 296 male C57BL/6N mice was performed to evaluate the biomechanical, biomolecular, biochemical, and histological impact of anti-inflammatory medications on fracture healing. A reproducible closed tibia fracture was created and stabilised with an intramedullary pin. Animals were randomised to placebo, ketorolac, ibuprofen, celecoxib, or rofecoxib treatment groups with biomechanical and biochemical testing at 4, 8, and 12 weeks. A second arm of the study was conducted in which animals were randomised to indomethacin or placebo treatment with biomechanical testing at 12 weeks. Histological and biomolecular studies were performed at 2 weeks on all groups in the first arm of the study. Biomechanical testing consisted of three-point bending evaluating maximum load, energy absorbed to maximum load, and stiffness. Safranin O-Fast Green stain was performed for histology. Biochemical quantifications of chondroitin and dermatan sulphate, hydroxyproline, total protein, and DNA content were performed. Osteocalcin and collagen types II and X were evaluated by in situ hybridisation. Some mechanical differences were seen between ketorolac and placebo at 4 weeks with respect to energy absorbed, but there were no differences in maximum load or stiffness seen between any treatment group and placebo at any time point. Indomethacin, celecoxib, rofecoxib, ibuprofen, and ketorolac did not significantly affect fracture healing in this young murine model.

Increased bone density associated with DLX3 mutation in the tricho-dento-osseous syndrome.

Tricho-dento-osseous syndrome (TDO) (OMIM #190320) is an autosomal dominant disorder characterized and named for the three most commonly affected tissues hair, teeth, and bones. Common to all individuals with TDO studied to date is a four base-pair deletion in the DLX3 gene on chromosome 17q21. This mutation is associated with a variable bone phenotype that includes alteration in intramembranous bone formation in the skull. The purpose of this study was to characterize and compare endochondral bone phenotypes and variability at central and peripheral locations of the skeleton by evaluating bone density in individuals having the same DLX3, 4 bp DEL,NT3198 mutation (OMIM 600525) and non-affected family members using dual-energy x-ray absorptiometry (DEXA). Thirty-four individuals (20 TDO-affected and 14 non-affected) participated in this prospective study. All participants were evaluated for the DLX3 mutation associated with TDO. All subjects received DEXA scans at common, literature-supported osteoporotic test regions including: (1) non-dominant distal radius/ulna, (2) femoral neck, and (3) lumbar spine L2-4. There was a significant increase (P < 0.05) in bone mineral density in TDO-affected individuals compared with control individuals at each test region. The markedly increased bone density in individuals having the DLX3, 4 bp DEL,NT3198 mutation shows that this alteration affects both endochondral and intramembranous bone formation and suggests that the DLX3 gene is important in bone formation and/or homeostasis of the appendicular skeleton.

Efficacy of alendronate in adults with cystic fibrosis with low bone density.

As adults with cystic fibrosis (CF) have enjoyed incremental increases in longevity over the last few decades, they have also been suffering from low bone density and its clinical manifestations, fractures and kyphosis. We conducted a placebo-controlled, randomized, double-blinded trial of alendronate (10 mg/day orally) (n = 24) compared with placebo (n = 24) for 1 year in 48 patients to improve bone mineral density at the spine as the primary endpoint. All patients received 800 IU of cholecalciferol and 1,000 mg of calcium carbonate. Both groups were similar in age, sex, CF mutations, bone density T scores, renal function, and body mass index at study onset. The alendronate-treated patients gained (mean +/- SD) 4.9 +/- 3.0% and 2.8 +/- 3.2% bone density after 1 year versus placebo, which lost (mean +/- SD) 1.8 +/- 4.0% and 0.7 +/- 4.7%, in spine and femur bone density, respectively (p < or = 0.001 for the spine; p = 0.003 for the femur). Urine N-telopeptide, a bone resorption marker, levels declined in the treatment group more than in the control group (p = 0.002), consistent with the known antiresorptive effects of bisphosphonates. Alendronate was more effective than placebo in improving spine and femur bone mineral density and is a promising agent for the long-term prevention and management of bone disease in patients with CF.

Tendon creep is potentiated by NKISK and relaxin which produce collagen fiber sliding.

The pentapeptide NKISK has been reported to inhibit the binding of decorin, a proteoglycan on the surface of collagen fibrils, to fibronectin, a tissue adhesion molecule. Relaxin has been shown to be effective in relaxing ligaments and other connective tissues. Through collagen staining studies, we have previously demonstrated that collagen fiber sliding is important during changes in ligament length. Because of our interest in fibril-fibril binding as it relates to changes in length of tendon or ligament, we investigated the potential of NKISK, relaxin, or both in combination to potentiate creep. We suspended stained rat tail tendons in test solutions under a constant stress and observed length changes and subsequent collagen fiber sliding. Both NKISK and relaxin potentiated rat tail tendon creep with changes in length most likely occurring as a result of collagen fiber sliding as evidenced by photomicrography.

An in vivo model of degenerative disc disease.

Although the precise etiology of low back pain is disputed, degeneration of the intervertebral disc is believed to play an important role. Many animal models have been described which reproduce the changes found in degenerative disc disease, but none allow for efficient, large-scale testing of purported therapeutic agents. The purpose of this study was to develop a simple animal model resembling degenerative disc disease using the intervertebral discs found in the tails of rats. The proximal two intervertebral discs in the tails of 20 rats were injected with either chondroitinase ABC or control (phosphate buffered saline, PBS). The tails were harvested at 2 weeks, and measurements were made of intervertebral disc height (measured radiographically and histologically), biomechanics (stiffness, hysteresis, and residual deformation), and histologic appearance. Treatment with chondroitinase ABC resulted in a significant loss in intervertebral disc height (radiographic intervertebral disc height, p=0.001; histologic intervertebral disc height, p<0.001) and significant increases in all biomechanical parameters (stiffness, p<0.001; hysteresis, p=0.006; residual deformation, p=0.004) compared to PBS controls. Intervertebral discs treated with chondroitinase ABC had significantly lower histologic grades for each grading category (nucleus pulposus (NP), annulus fibrosus, and proteoglycan staining) compared to controls. The results of injury with chondroitinase ABC were similar to the findings in degenerative disc disease: reduced intervertebral disc height, diminished proteoglycan content, loss of NP cells, and increased stiffness of the disc. Thus, the model appears to be a reasonable tool for the preliminary in vivo evaluation of proposed treatments for degenerative disc disease.