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Baseline Controls (baseline + control)
Selected AbstractsTower Climbing Exercise Started 3 Months After Ovariectomy Recovers Bone Strength of the Femur and Lumbar Vertebrae in Aged Osteopenic Rats,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 1 2003Takuya Notomi Abstract To determine both the preventive and recovery effects of tower climbing exercise on mass, strength, and local turnover of bone in ovariectomized (OVX) rats, we carried out two experiments. In experiment I, 60 Sprague-Dawley rats, 12 months of age, were assigned to four groups: a Baseline Control, Sham-Operated Sedentary, OVX-Sedentary and OVX-Exercise rats. Rats voluntarily climbed a 200-cm tower to drink water from a bottle set at the top. At 3 months, OVX elevated both the femoral cortex and lumbar trabecular turnover, leading to a reduction in bone mass and strength. However, in OVX-Exercise rats, those values were maintained at the same level as in the Sham-Sedentary rats. Thus, the climbing exercise, started after 3 days of OVX, prevented OVX-induced cortical and trabecular bone loss by depressing turnover elevation. After confirming the preventive effect, we evaluated the recovery effect of exercise. In experiment II, 90 Sprague-Dawley rats, 12 months of age, were assigned to six groups: a Baseline control, two groups of Sham-Operated Sedentary and OVX-Sedentary, and OVX-Exercise rats. The exercise started 3 months after the OVX operation. At 3 months, OVX increased the trabecular bone formation rate and osteoclast surface, leading to a decrease in compressive strength. In the midfemur, the cross-sectional area, moment of inertia, and bending load values decreased. At 6 months, in the OVX-Exercise rats, the parameters of breaking load in both the lumbar and midfemur, lumbar bone mass, and the total cross-sectional area recovered to the same levels as those in the Sham-Sedentary rats. However, the cortical bone area did not recover. Periosteal bone formation increased, while endosteal bone formation decreased. These results showed that the climbing exercise had both a preventive and recovery effect on bone strength in OVX rats. In the mid-femur, effects on bone formation were site-specific, and the cross-sectional morphology was improved without an increase in cortical bone area, supporting cortical drift by mechanical stimulation. [source] In vitro antimicrobial effect of chlorhexidine-impregnated gutta percha points on Enterococcus faecalisINTERNATIONAL ENDODONTIC JOURNAL, Issue 2 2004J. N. Lui Abstract Aim, To evaluate the in vitro antimicrobial effect of chlorhexidine-impregnated gutta percha points, Roeko activ point (Roeko, Langenau, Germany) on Enterococcus faecalis. Methodology, Human maxillary premolar roots were prepared with .04 rotary ProFile instruments to a master apical file size 40, autoclave-sterilized and then infected with E. faecalis (ATCC 29212) for 3 weeks. Baseline controls were carried out verifying negligible effects of plain gutta percha cones on E. faecalis. Subsequent to intracanal placement of calcium hydroxide, ,activ points' or saline (positive control) and the 2-week incubation in 54 root specimens, dentine sampling at depths of 100 and 250 µm was carried out using .04 rotary ProFile instruments at sizes 60 and 90 to assess the quantity of bacteria present. Inactivating agents were used prior to sampling and the colony-forming units (CFU) of E. faecalis were then plate-counted after culturing. Statistical analysis was completed using the paired t -test. Results, In comparison to the positive control, treatment with calcium hydroxide (P = 0.000 and 0.000) or activ points (P = 0.000 and 0.002) produced significantly lower colony counts of E. faecalis at dentine depths of 100 and 250 µm, respectively. Calcium hydroxide (2.10 × 102 CFU mL,1) was significantly more effective than activ points (1.58 × 103 CFU mL,1) at 100 µm (P = 0.013), but not at 250 µm (P = 0.353). Neither of these two medications was able to eliminate E. faecalis completely. Conclusions, Chlorhexidine-impregnated activ points did not possess an in vitro inhibitory activity strong enough to eliminate E. faecalis completely from infected dentinal tubules. [source] Recovery of Trabecular and Cortical Bone Turnover After Discontinuation of Risedronate and Alendronate Therapy in Ovariectomized RatsJOURNAL OF BONE AND MINERAL RESEARCH, Issue 10 2008Robyn K Fuchs Abstract Alendronate (ALN) and risedronate (RIS) are bisphosphonates effective in reducing bone loss and fractures associated with postmenopausal osteoporosis. However, it is uncertain how long it takes bone turnover to be re-established after treatment withdrawal, and whether this differs between the two drugs. The objective of this study was to determine the time required to re-establish normal bone turnover after the discontinuation of ALN and RIS treatment in an animal model of estrogen-deficiency osteoporosis. Two hundred ten, 6-mo-old female Sprague-Dawley rats were ovariectomized and 6 wk later were randomized into baseline controls (n = 10) and four treatment groups (n = 50/group): vehicle-treated controls (CON; 0.3 ml sterile water), ALN (2.4 ,g/kg), low-dose RIS (RIS low; 1.2 ,g/kg), and high-dose RIS (RIS high; 2.4 ,g/kg). Treatments were administered 3 times/wk by subcutaneous injection. Baseline controls were killed at the initiation of treatment. Other groups were treated for 8 wk, and subgroups (n = 10/ treatment group) were killed 0, 4, 8, 12, and 16 wk after treatment was withdrawn. Static and dynamic histological analyses were performed for cortical (tibial diaphysis) and trabecular (proximal tibia and L4 vertebrae) bone. DXA and mechanical testing was performed on the L5 vertebra. After 8 wk of treatment, trabecular bone turnover rates were significantly suppressed in all drug-treated animals. Trabecular bone formation rate (BFR/BS) remained significantly lower than vehicle in bisphosphonate-treated animals through 12 wk. Sixteen weeks after treatment withdrawal, trabecular BFR/BS in the proximal tibia was re-established in animals treated with RIS but not in animals treated with ALN compared with controls. BMD of the fifth lumbar vertebra remained significantly higher than controls 16 wk after treatment withdrawal in ALN-treated animals but not in RIS-treated animals. Despite reductions in BMD and increases in bone turnover, ultimate force of the fifth lumbar vertebra remained significantly higher in all drug-treated animals through 16 wk after withdrawal. [source] Climbing Exercise Increases Bone Mass and Trabecular Bone Turnover Through Transient Regulation of Marrow Osteogenic and Osteoclastogenic Potentials in Mice,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 11 2003Toshiharu Mori Abstract To investigate the relationship between the effects of bone turnover and bone marrow cell development in bone cells, we developed a mouse voluntary climbing exercise model. Climbing exercise increased bone volume and transient osteogenic potential of bone marrow. This model would be suitable for investigating the mechanistic roles of mechanical loading. Introduction: The relationship between bone mass gain and local bone formation and resorption in mechanically loaded bone is not well understood. Materials and Methods: Sixty-five C57BL/6J mice, 8 weeks of age, were assigned to five groups: a baseline control and two groups each of ground control and climbing exercise mice for 2 and 4 weeks. Mice were housed in a 100-cm tower and had to climb toward a bottle placed at the top to drink water. Results: Compared with the ground control, bone mineral density of the left femur increased in the climbing mice at 4 weeks. At 2 and 4 weeks, bone formation rate (BFR/BS) of periosteal surface, the cross-sectional area, and moment of inertia were increased in the climbing mice, whereas BFR/BS and eroded surface (ES/BS) of endosteal surface did not differ. The trabecular bone volume (BV/TV) of the proximal tibia increased in climbing mice, and osteoclast surface (Oc.S/BS) and osteoclast number decreased at 2 weeks. At 4 weeks, there were increases in BV/TV and parameters of bone formation, including mineralized surface, mineral apposition rate, and bone formation rate. In marrow cell cultures from the tibia, the number of alkaline phosphatase+ colony forming units-fibroblastic and the area of mineralized nodule formation in climbing mice were increased, and the number of osteoclast-like TRACP+ multinucleated cells was lower at 2 weeks. At 4 weeks, these parameters recovered to the levels of the ground controls. Conclusion: Our results indicate that climbing increased trabecular bone volume and reduced bone resorption, with a subsequent increase in bone formation. Intermittent climbing downregulates marrow osteoclastogenic cells and upregulates osteogenic cells initially, but further exercise seemed to desensitize them. Cortical envelopes were enlarged earlier, but the response seems to differ from trabecular bone. [source] Recovery of Trabecular and Cortical Bone Turnover After Discontinuation of Risedronate and Alendronate Therapy in Ovariectomized RatsJOURNAL OF BONE AND MINERAL RESEARCH, Issue 10 2008Robyn K Fuchs Abstract Alendronate (ALN) and risedronate (RIS) are bisphosphonates effective in reducing bone loss and fractures associated with postmenopausal osteoporosis. However, it is uncertain how long it takes bone turnover to be re-established after treatment withdrawal, and whether this differs between the two drugs. The objective of this study was to determine the time required to re-establish normal bone turnover after the discontinuation of ALN and RIS treatment in an animal model of estrogen-deficiency osteoporosis. Two hundred ten, 6-mo-old female Sprague-Dawley rats were ovariectomized and 6 wk later were randomized into baseline controls (n = 10) and four treatment groups (n = 50/group): vehicle-treated controls (CON; 0.3 ml sterile water), ALN (2.4 ,g/kg), low-dose RIS (RIS low; 1.2 ,g/kg), and high-dose RIS (RIS high; 2.4 ,g/kg). Treatments were administered 3 times/wk by subcutaneous injection. Baseline controls were killed at the initiation of treatment. Other groups were treated for 8 wk, and subgroups (n = 10/ treatment group) were killed 0, 4, 8, 12, and 16 wk after treatment was withdrawn. Static and dynamic histological analyses were performed for cortical (tibial diaphysis) and trabecular (proximal tibia and L4 vertebrae) bone. DXA and mechanical testing was performed on the L5 vertebra. After 8 wk of treatment, trabecular bone turnover rates were significantly suppressed in all drug-treated animals. Trabecular bone formation rate (BFR/BS) remained significantly lower than vehicle in bisphosphonate-treated animals through 12 wk. Sixteen weeks after treatment withdrawal, trabecular BFR/BS in the proximal tibia was re-established in animals treated with RIS but not in animals treated with ALN compared with controls. BMD of the fifth lumbar vertebra remained significantly higher than controls 16 wk after treatment withdrawal in ALN-treated animals but not in RIS-treated animals. Despite reductions in BMD and increases in bone turnover, ultimate force of the fifth lumbar vertebra remained significantly higher in all drug-treated animals through 16 wk after withdrawal. [source] Effects of h-PTH on cancellous bone mass, connectivity, and bone strength in ovariectomized rats with and without sciatic-neurectomyJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 3 2004Y. Kasukawa Abstract The purpose of this study was to determine whether h-PTH (1-34) treatment would recover cancellous bone connectivity and bone strength in ovariectomized (OVX) or ovariectomized and sciatic-neurectomized (OVX + NX) rats. Seven-month-old female Wistar rats were treated with h-PTH or vehicle (6.0 ,g/kg, six times a week, subcutaneously) for four weeks beginning 4, 8, or 12 weeks after OVX or OVX + NX. These were compared to age-matched baseline and sham-operated groups. Right tibiae were used for bone histomorphometry and node-strut analysis, and left tibiae were used for mechanical testing. The bone formation rates in the OVX and OVX + NX rats treated with h-PTH were significantly higher than those in their baseline controls, h-PTH treatment increased the node numbers and failure energies in the OVX rats, compared to their baseline controls, at all time points. However, in the OVX + NX rats, the effects of h-PTH treatment on the node number and failure energy were observed only at four weeks after surgery, but not at eight weeks or 12 weeks after surgery. These results suggest that the lowest limit, at which trabecular connectivity and bone strength are able to be restored by h-PTH, occurred between four and eight weeks in OVX + NX rats, but not in OVX rats, h-PTH cannot recover trabecular connectivity and bone strength in advanced osteopenia. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source] | ||||||||||