Altered mechanical behavior of demineralized bone following therapeutic radiation.

Post-radiotherapy (RTx) bone fragility fractures are a late-onset complication occurring in bone within or underlying the radiation field. These fractures are difficult to predict, as patients do not present with local osteopenia. Using a murine hindlimb RTx model, we previously documented decreased mineralized bone strength and fracture toughness, but alterations in material properties of the organic bone matrix are largely unknown. In this study, 4 days of fractionated hindlimb irradiation (4 × 5 Gy) or Sham irradiation was administered in a mouse model (BALB/cJ, end points: 0, 4, 8, and 12 weeks, n = 15/group/end point). Following demineralization, the viscoelastic stress relaxation, and monotonic tensile mechanical properties of tibiae were determined. Irradiated tibiae demonstrated an immediate (day after last radiation fraction) and sustained (4, 8, 12 weeks) increase in stress relaxation compared to the Sham group, with a 4.4% decrease in equilibrium stress (p < .017). While tensile strength was not different between groups, irradiated tibiae had a lower elastic modulus (-5%, p = .027) and energy to failure (-12.2%, p = .012) with monotonic loading. Gel electrophoresis showed that therapeutic irradiation (4 × 5 Gy) does not result in collagen fragmentation, while irradiation at a common sterilization dose (25 kGy) extensively fragmented collagen. These results suggest that altered collagen mechanical behavior has a role in postirradiation bone fragility, but this can occur without detectable collagen fragmentation. Statement of Clinical Significance: Therapeutic irradiation alters bone organic matrix mechanics and which contribute to diminished fatigue strength, but this does not occur via collagen fragmentation.

Meeting ultraviolet B radiation requirements of amphibians in captivity: a case study with mountain chicken frogs (Leptodactylus fallax) and general recommendations for pre-release health screening.

Conservation breeding programmes are a tool used to prevent amphibian extinctions. The husbandry requirements of amphibians are complex. Ongoing research is needed to ensure optimal management of those captive-bred animals destined, in particular, for reintroduction. The UV-B and vitamin D3 requirements of amphibians are largely unknown. Metabolic bone disease has been reported in a number of species. These include the Critically Endangered mountain chicken frog (Leptodactylus fallax) reared in captivity on diets supplemented with a high-calcium multivitamin and mineral supplement containing vitamin D3 but without UV-B provision. Captive-bred L. fallax being reared for reintroduction to Montserrat were provided with UV-B radiation from metamorphosis and were fed on insects supplemented with vitamins and minerals. Overlapping heat, light and UV-B gradients were provided, mimicking what we believe best represents the natural situation and thereby facilitated self-regulation of UV-B exposure. A subset of 10 frogs was periodically radiographed to assess skeletal health. Radiographic bone density and anatomical integrity appeared unremarkable when compared with a wild caught L. fallax. In addition to other routine health-screening, we recommend that radiography be performed to a structured schedule on a subset of all captive-bred and reared amphibians to assess skeletal health and to gauge the appropriateness of captive husbandry. We demonstrate here that, through the appropriate provision of a combination of both UV-B radiation and dietary supplementation, L. fallax can be bred and reared in captivity with healthy skeletal development.

Healing of normal and osteopenic bone with titanium implant and low-level laser therapy (GaAlAs): a histomorphometric study in rats.

The study investigates the influence of low-level laser therapy (LLLT) on bone healing in the femur of osteopenic and normal rats with titanium implants. Ovariectomy and control group were randomly submitted to LLLT, which was applied by gallium-aluminum-arsenium (GaAlAs) laser at the surgical site before and after placing the implant, for seven times. Histomorphometric and statistical analysis were performed. Most irradiated groups showed higher values than the nonirradiated groups. The GaAlAs infrared diode laser may improve the osseointegration process in osteopenic and normal bone, particularly based on its effects in the initial phase of bone formation.

Effect of low-power gallium-aluminum-arsenium laser therapy (830 nm) in combination with bisphosphonate treatment on osteopenic bone structure: an experimental animal study.

Laser therapy is able to modulate cell metabolism and accelerate the repair of fracture. Little attention has been given to the effect of laser on bone with osteopenia or osteoporosis. The purpose of our study was to verify the effect of laser therapy in combination with bisphosphonate on osteopenic bone structure. The 35 Wistar female rats used were divided into five groups: (1) sham-operation rats (control), (2) ovariectomized (OVX'd) rats with osteopenia, (3) OVX'd rats with osteopenia treated with laser, (4) OVX'd rats with osteopenia treated with bisphosphonate and (5) OVX'd rats with osteopenia treated with bisphosphonate and laser. Groups 3 and 5 were given daily 6 mg doses of bisphosphonate orally. Groups 4 and 5 underwent low level laser therapy [gallium-aluminum-arsenium (GaAlAs) laser, 830 nm, 50 mW and 4 J/cm(2)] on the femoral neck and vertebral segments (T13-L2). Both treatments were performed over an 8-week period. Rats from the osteopenic control and osteopenic + laser groups presented marked osteopenia. In the osteopenic + bisphosphonate group, the trabecular bone volume in vertebra L2 was significantly greater than in the osteopenic control group. Notably, in the association between laser and bisphosphonate, the trabecular bone volume was significantly greater in vertebrae L2 and T13 and was similar to that in the sham-operation control group. It was concluded that the laser therapy associated with bisphosphonate treatment was the best method for reversing vertebral osteopenia caused by the ovariectomy.

Effects of 830-nm laser, used in two doses, on biomechanical properties of osteopenic rat femora.

OBJECTIVE: The aim of this study was to investigate the effects of photoradiation--infrared at 830 nm--used in two doses, on femora of osteopenic rats. BACKGROUND DATA: Osteoporosis has recently been recognized as a major public health problem. Based on stimulatory effects of photoradiation on the proliferation of bone cells, we hypothesized that photoradiation would be efficient in improving bone mass in osteopenic rats. METHODS: Sixty female animals, divided into six groups, were used: sham-operated control (SC), osteopenic control (OC), sham-operated irradiated with the dose of 120 J/cm(2) (I120), osteopenic irradiated with the dose of 120 J/cm(2) (O120), sham-operated irradiated with the dose of 60 J/cm(2) (I60), and osteopenic irradiated with the dose of 60 J/cm(2) (O60) Animals were 90 days old when operated. Laser irradiation was initiated 8 weeks after operation, and it was performed 3 times a week for 2 months. Femora were submitted to a biomechanical test and to a physical properties evaluation. RESULTS: Maximal load of O120 did not show any difference when compared with SC and I120, but it was higher than the O60 group. Wet weight, dry weight, and bone volume of O60 and O120 did not show any difference when compared with SC. CONCLUSION: The results of the present study indicate that photoradiation had stimulatory effects on femora of osteopenic rats, mainly at the dose of 120 J/cm.(2) However, further studies are needed to investigate the effects of different parameters, wavelengths, and sessions of applications on ovariectomized rats.

[Potentials for using radiation treatment in complicated diabetic osteoarthropathy]. / Vozmozhnosti primeneniia luchevogo lecheniia oslozhnennoi diabeticheskoi osteoartropatii.

The possibility of gamma-beam therapy of aggravated diabetic osteoarthropathy is discussed. Seventy patients were exposed to local radiation (orthovolt X-ray therapy, generation voltage being 200 kV) for suppurative inflammation of the foot soft and bony tissues. The total focal dose was 300 to 500 Gy. Previous drug- and ointment treatment performed in all the patients was unsuccessful, as well as the ulcer purification and drainage. As a result of gamma-beam therapy a stable clinical effect was seen in 65 patients within 1 1/2 to 5 years' follow up: inflammation disappeared followed by the wound healing and bone repairing. The results obtained allow one to recommend this method as a component of the complex therapy of the pathology above.