Ariane Zamarioli

The osteogenic effects of swimming, jumping, and vibration on the protection of bone quality from disuse bone loss

We assessed and compared the effects of swimming, jumping, and vibration therapies on the prevention of bone loss because of unloading. Eighty Wistar rats were randomly divided into eight groups: S, permanent hind limb‐suspended rats; CON, control rats; S + Swim, unloading interrupted by swimming exercise; S + CSwim, suspension interrupted by regular weight‐bearing with the same duration as in the S + Swim protocol; S + Jump, unloading interrupted by jumping exercise; S + CJump, suspension interrupted for regular weight‐bearing as in the S + Jump group; S + Vibr, unloading interrupted by vibration; and S + CVibr, suspension with interruptions for regular weight‐bearing with the same protocol as that used for the S + Vibr rats. At the end of the experiment, the bone mineral density, bone strength, histomorphometric parameters, and serum levels of the bone markers were analyzed. The hind limb‐suspended rats exhibited bone quality loss. In contrast, the trained rats showed a significant increase in bone mass, bone strength, bone formation, and serum levels of bone markers compared with the respective controls. Although we did not find a significant difference among the three physical exercises, the osteogenic effect of vibration was slightly lower than that of swimming and jumping. Thus, all physical exercises were efficient in preventing bone loss because of unloading and preserving bone quality.

Efeitos da aplicação do laser de baixa potência na regeneração do nervo isquiático de ratos

Peripheral nerves are commonly subject to traumatic injuries, leading to functional loss. Low-power laser therapy has been used in order to minimize harmful effects of inflammation and to accelerate healing of injured tissues. The purpose of this study was to assess the effect of 830 nm-laser irradiation on rat sciatic nerves submitted to crush. Twenty male Wistar rats had their sciatic nerve crushed and were divided into 4 groups (n=5): Sham7 and Sham14, placebo-treated for 7 and 14 days; L7 and L14, laser-treated (at 4 J/cm²) for 7 and 14 days. Sham group animals were submitted to the same procedures, but with the laser turned off. Assessed parameters were inflammatory infiltrates, fibroblasts, myelin sheath destruction, and axonal degeneration. The statistical analysis showed significant differences in three parameters: L14 animals showed more fibroblasts (p=0.0001), lesser myelin sheath degeneration (p=0.007), and lesser inflammatory infiltrates (p=0.001). Low-power laser therapy hence contributed to reduce the inflammatory process due to rat sciatic nerve injury.

MRI Abnormalities of the Acetabular Labrum and Articular Cartilage Are Common in Healed Legg-Calvé-Perthes Disease with Residual Deformities of the Hip

BACKGROUND Varying degrees of femoral deformity may result as Legg-Calvé-Perthes disease heals. Our aims were to investigate the prevalence of abnormalities of the acetabular labrum and cartilage, using noncontrast magnetic resonance imaging, and to correlate the findings with radiographic deformities that may exist after the healing of Legg-Calvé-Perthes disease. METHODS In a sample of ninety-nine patients with healed Legg-Calvé-Perthes disease, anteroposterior and lateral radiographs were used to assess the Stulberg classification, femoral head size and sphericity, femoral neck morphology, and acetabular version. A subgroup of fifty-four patients (fifty-nine hips) underwent noncontrast magnetic resonance imaging of the hip an average of eight years after disease onset. The acetabular labrum was evaluated according to a modified classification system, and the acetabular cartilage was evaluated for the presence of delamination and defects. The association among abnormalities of the acetabular labrum, articular cartilage, and radiographic deformities was assessed. RESULTS Abnormalities of the acetabular labrum and cartilage were found on magnetic resonance imaging scans in 75% and 47% of the hips, respectively. An alpha angle of ≥55° was the deformity most significantly associated with labral and cartilage abnormalities, followed by coxa brevis. Coxa magna and a higher greater trochanter showed a significant association with labral abnormalities only. Acetabular retroversion showed an increased risk for labral abnormalities when the alpha angle was normal. When deformities coexisted, the alpha angle showed the greatest relative risk for abnormality. CONCLUSIONS On the basis of magnetic resonance imaging evaluation of the hip, labral and cartilage abnormalities were a common finding in patients with healed Legg-Calvé-Perthes disease. Our results suggest that hip deformities are significantly associated with labral and cartilage abnormalities on magnetic resonance imaging, and the main predisposing factor was the asphericity of the femoral head with a reduced femoral head-neck offset.

Standing Frame and Electrical Stimulation Therapies Partially Preserve Bone Strength in a Rodent Model of Acute Spinal Cord Injury

ObjectiveThe aim of this study was to compare the effect of standing frame and electrical stimulation on bone quality in a rodent transection model of spinal cord injury (SCI). DesignSeven-week-old male Wistar rats were divided into four groups: sham, n = 10; SCI, n = 7; SCI + standing frame, n = 7; and SCI + electrical stimulation, n = 7. Complete SCI was generated by surgical transection of the cord at the T10 level. Therapies were initiated 3 days after the surgery, 3 days/wk, 20 mins/day, for 30 days. Animals were killed on day 33 postinjury. ResultsNo treatment preserved bone mineral density at any skeletal site tested (P = 0.08–0.99). Standing frame therapy preserved maximal load at the lumbar vertebral body (14% vs. 37% reduction, P = 0.01) and prevented SCI-induced loss of stiffness at both the femur (8% vs. 37% reduction, P = 0.03) and the tibia (35% vs. 56% reduction, P < 0.0001). Electrical stimulation therapy reduced SCI-induced loss of stiffness at the tibia only (40% vs. 56% reduction, P = 0.003). ConclusionsStanding frame and electrical stimulation may have potential as future therapeutic modalities to treat or prevent bone loss after SCI.

Whole-body vibration improves fracture healing and bone quality in rats with ovariectomy-induced osteoporosis

PURPOSE To investigate the effect of vibration therapy on the bone callus of fractured femurs and the bone quality of intact femurs in ovariectomized rats. METHODS Fifty-six rats aged seven weeks were divided into four groups: control with femoral fracture (CON, n=14), ovariectomized with femoral fracture (OVX, n=14), control with femoral fracture plus vibration therapy (CON+VT, n=14), and ovariectomized with femoral fracture plus vibration therapy (OVX+VT, n=14). Three months after ovariectomy or sham surgery, a complete fracture was produced at the femoral mid-diaphysis and stabilized with a 1-mm-diameter intramedullary Kirschner wire. X-rays confirmed the fracture alignment and fixation. Three days later, the VT groups underwent vibration therapy (1 mm, 60 Hz for 20 minutes, three times per week for 14 or 28 days). The bone and callus quality were assessed by densitometry, three-dimensional microstructure, and mechanical test. RESULTS Ovariectomized rats exhibited a substantial loss of bone mass and severe impairment in bone microarchitecture, both in the non-fractured femur and the bone callus. Whole-body vibration therapy exerted an important role in ameliorating the bone and fracture callus parameters in the osteoporotic bone. CONCLUSION Vibration therapy improved bone quality and the quality of the fracture bone callus in ovariectomized rats.

Systemically Alendronate was Incorporated Into Dental Tissues but did not Cause Morphological or Mechanical Changes in Rats Teeth

This study evaluated the effect of the systemic use of sodium alendronate in rats in vivo. Forty‐five Wistar rats aged 36 to 42 days and weighing 200 to 230 g were randomly assigned to a control group (n = 20), which received distilled water, and an experimental group (n = 25), which received 2 weekly doses of 1 mg/kg of chemically pure sodium alendronate. The animals were killed after 60 days of treatment. The tibias were removed for analysis of bone mineral density by dual‐energy X‐ray absorptiometry (DXA). Then, the maxillary incisors were extracted for analysis of the mineralized dental tissues using fluorescence spectroscopy (FS), scanning electron microscopy (SEM), bright field microscopy (BFM), and cross‐sectional microhardness (CSMH) testing. DXA and CSMH data were subjected to statistical analysis by Kruskal‐Wallis test (5% significance level). The experimental group presented higher bone mineral density than the control group by DXA. FS analysis revealed presence of alendronate in the mineralized dental tissues of the specimens of the experimental group. Significant morphological differences were not found by SEM and BFM. Enamel and dentin (100 and 300 μm from the dentinoenamel junction) CSMH data did not show significant difference between the control and experimental groups. Based on the obtained results, we conclude that while alendronate increased the bone mineral density and was incorporated into the mineralized dental tissues it did not cause significant alterations in the morphology and microhardness of rat incisor enamel and dentin. Microsc. Res. Tech. 75:1265–1271, 2012.

Esteira com velocidade controlada para captação da marcha

Histological and electrophysiological methods for evaluation of peripheral nerve regeneration do not faithfully reproduce the functional index of limbs, even in controlled experimental conditions. Some methods of functional evaluation have been proposed, but their correlation to histological and electrophysiological data is not completely established, requiring more investigations with improvement of collection, management and processing of obtained data. In this study we developed a treadmill with controlled speed for recording footprint of rats submitted to different kinds of sciatic, fibular and tibial nerve lesions. The footprints were obtained on a walking track by means of a webcam connected to the treadmill and a computer with capacity to record the gait that will be submitted to functional evaluation. The developed treadmill allows the collection and filming of gaits and it has been tested in current experimental studies in rats with sciatic nerve lesion submitted to different kinds of treatment. The treadmill also enables researchers to record gait with constant, controlled and pre-established speed, with the possibility of direct visualization through the treadmill wall. In this manner, some variables that could damage the results of the research are resolved.

Torque de inserção e resistência ao arrancamento dos parafusos vertebrais com alma cilíndrica e cônica

OBJECTIVE: To evaluate insertion torque and pullout strength of three different screws used in the anterior fixation of the spine, considering the influence of the diameter of the pilot hole (DOP), the test specimen density (CDP), and the screw thread design. METHODS: The authors used polyurethane test specimens with two densities: 0.16 and 0.32 g/cm3, and three types of screws (USS I, USS II posterior, and USS II anterior). In the first stage, the pilot hole was made with a 3.8 mm probe for all screws; in the second stage, with a probe smaller than the inner diameter of the screws (3.5 mm for screws USS I; 3.4 mm for USS II posterior screws, and 3.0 mm for USS II anterior screws). 12 experimental groups were formed with ten specimen tests in each group, according to the polyurethane density, DOP, and the type of screw used. Torque was measured during insertion of the screws and the pullout strength by a mechanical assay in a universal test machine. RESULTS: The maximum insertion torque presented a decreasing value in test specimens of 0.16 g/cm3 and 0.32 g/cm3 and in all pilot hole diameters. Maximum pullout strength in test specimens of 0.16 g/cm3 and 3.8 mm of perforation diameter was greater in USS II posterior screws than in USS I screws. With the perforation diameter smaller than the inner screw diameter, USS II posterior and anterior screws presented higher values than the USS I screw. In test specimens with 0.32 g/cm3 of density and perforation diameter of 3.8 mm, the pullout strength of USS II posterior and USS I screws was greater than that of USS II anterior screws. With the smaller perforation diameter than the inner diameter, the values were decreasing between the USS II posterior screw, then the USS II anterior screw, and then the USS I screw. CONCLUSION: Insertion torque and pullout strength of the screws used in the anterior fixation of the vertebral spine are influenced by the test specimen density, by the screw thread design, and by the diameter of the pilot hole.

Swimming Activity Prevents the Unloading Induced Loss of Bone Mass, Architecture, and Strength in Rats.

We investigated whether swimming activity associated with a three-week period of hypoactivity could prevent the deleterious effects of disuse on the tibias of tail-suspended rats. Forty Wistar rats were divided into five groups: (HS) permanently hindlimb suspension rats; (HS + Swim) rats submitted to unloading interrupted by swimming exercise; (HS + WB) hindlimb suspension rats with interruption for regular weight bearing for the same length of time as the HS+Swim rats; (Control) control rats that were allowed regular cage activities; and (Control + Swim) control rats that underwent swimming exercise. At the end of the experiment, bone mineral density, bone strength, and trabecular quantification were analyzed. The hindlimb-suspended rats exhibited bone quality loss (significant decrease in BMD, bone strength, and deterioration of trabecular and cortical bone architecture; decrease in BV/TV, TbN, TbTh, ConnD, CtV, and CtTh; and increase in TbSp) when compared to control rats. In contrast, trained rats showed a significant increase of 43% in bone mass, 29% in bone strength, 58% in trabecular thickness, 85% in bone volume, 27% in trabeculae number, and 30% in cortical volume, when compared to the hindlimb-suspended rats. We conclude that swimming activity not only ameliorates but also fully prevents the deleterious effects on bone quality in osteopenic rats.

Boron supplementation improves bone health of non-obese diabetic mice

Diabetes Mellitus is a condition that predisposes a higher risk for the development of osteoporosis. The objective of this study was to investigate the influence of boron supplementation on bone microstructure and strength in control and non-obese diabetic mice for 30days. The animals were supplemented with 40μg/0,5ml of boron solution and controls received 0,5ml of distilled water daily. We evaluated the biochemical parameters: total calcium, phosphorus, magnesium and boron; bone analysis: bone computed microtomography, and biomechanical assay with a three point test on the femur. This study consisted of 28 animals divided into four groups: Group water control - Ctrl (n=10), Group boron control - Ctrl±B (n=8), Group diabetic water - Diab (n=5) and Group diabetic boron - Diab±B (n=5). The results showed that cortical bone volume and the trabecular bone volume fraction were higher for Diab±B and Ctrl±B compared to the Diab and Ctrl groups (p≤0,05). The trabecular specific bone surface was greater for the Diab±B group, and the trabecular thickness and structure model index had the worst values for the Diab group. The boron serum concentrations were higher for the Diab±B group compared to non-supplemented groups. The magnesium concentration was lower for Diab and Diab±B compared with controls. The biomechanical test on the femur revealed maintenance of parameters of the bone strength in animals Diab±B compared to the Diab group and controls. The results suggest that boron supplementation improves parameters related to bone strength and microstructure of cortical and trabecular bone in diabetic animals and the controls that were supplemented.