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Objective To study the effect of dynamic pressure on the expression of parathyroid hormone-related protein (PTHrP)mRNA in metaphyseal cartilage stem cells of rats so as to further explore whether fiber actin (F-actin)is involved in the mechanical signal transduction process.Methods We isolated and cultured metaphyseal cartilage stem cells of rats by immunomagnetic beads.The third-generation rat metaphyseal cartilage stem cells were randomly divided into four groups:0%,3%,6%,and 12% deformed groups according to the size of dynamic pressure strength.We used a self-prepared dynamic tonic culture device to exert different intensity of pressure on each group of cells for 24 hours.Flow cytometry was used to detect the cell cycle distribution and apoptosis rate.The expression of PTHrP mRNA in each group was detected by Rea-l time quantitative PCR. Furthermore,the third-generation rat metaphyseal cartilage stem cells were randomly divided into four groups:control group,simple pressure group (6% deformation),pressure+cytoskeleton relaxin D group,and simple cytoskeleton relaxin D group according to whether or not to apply pressure and cytoskeleton relaxin D.F-actin fibers in each group of cells were stained with phalloidin and placed under a laser scanning confocal microscope.The expression of PTHrP mRNA in each group was detected by Real-time quantitative PCR.Results The results of flow cytometry showed no significant difference in G0/G1,G2/M and S phases between 0%,3%,6% and 12% deformed groups (P＞0.05).There was no significant difference in the apoptosis rate between 3% and 6% deformed groups compared with 0% deformed group (P＞0.05).The apoptosis rate was significantly higher in 1 2 % deformed group than in control group (P＜0.05).The results of laser confocal microscopy showed that the arrangement of F-actin fibers in the pressure group was neat and parallel compared with that in the control group, which was consistent with the direction of force.The intracellular F-actin fiber structure in pressure+cytoskeleton relaxin D group and simple cytoskeleton relaxin D group was destroyed and aggregated into clusters.Real-time quantitative PCR results showed that PTHrP mRNA expression did not significantly differ between 3% and 0% deformed groups (P＞0.05).The expression of PTHrP mRNA in 6% and 12% deformed groups was significantly higher than that in 0% group (P＜0.05).The expression of PTHrP mRNA in the cells of simple pressure group was significantly higher than that in the control group (P＜0.05).There was no significant difference in the expression of PTHrP mRNA between simple cytoskeleton relaxin D group and control group (P＞0.05).The mRNA expression of PTHrP was higher in pressure+cytoskeleton relaxin D group than that in control group,but lower than in simple pressure group (P＜0.05).Conclusion The dynamic pressure of proper intensity can increase the mRNA expression of PTHrP in chondrocytes of metaphyseal hypertrophy in rats,and F-actin is involved in the mechanical signal transduction process.
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Objective To study the effect of dynamic stress stimulation on the expression of Sox9 mRNA and protein in metaphyseal chondrocytes in vitro, and to explore the specific mechanism of mechanical signal transduction. Methods The rat metaphyseal chondrocytes separated and cultured for the 3rd generation in vitro were randomly divided into four groups:control group (all interventions were not applied), simple dynamic pressure group (a dynamic pressure stimulus with a size of 90 mmHg and a frequency of 0.1 Hz was applied using an open pressure control culture system), simple calcium antagonist group (the concentration of 10μmol/L nifedipine was given) and dynamic pressure+calcium antagonist group (a dynamic pressure stimulus with a size of 90 mmHg, frequency of 0.1 Hz and concentration of 10 μmol/L nifedipine were given at the same time). The expression of Sox9 mRNA was detected after 24 h intervention by real-time quantitative polymerase chain reaction (RT-PCR) in four groups. The expression of Sox9 protein was detected by Western blot assay. The intracellular free Ca2+ in metaphyseal chondrocytes was labeled with Fluo-3/AM, and the average fluorescence intensity detected by laser scanning confocal scanning microscopy was compared between four groups. Results The expression of Sox9 mRNA was 3.81 times higher in dynamic stress group than that in the control group, and the protein expression level was 2.33 times higher than that of the control group (P<0.05). There were no significant differences in the expression of Sox9 mRNA and protein between the calcium antagonist group and the control group. The expressions of Sox9 mRNA and protein were lower in dynamic pressure+calcium antagonist group than those in the dynamic stress group, but which were higher than those of control group(P<0.05). The results of average fluorescence intensity showed that there was no significant difference in the intracellular free Ca2+ concentration between four groups (P > 0.05). Conclusion Dynamic stress stimulation can increase the expression of Sox9 mRNA and protein in rat metaphyseal chondrocytes. There is calcium channel involvement in the mechanical signal transduction.
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Objective To study the effect of dynamic stress stimulation on the expression of Sox9 mRNA and protein in metaphyseal chondrocytes in vitro, and to explore the specific mechanism of mechanical signal transduction. Methods The rat metaphyseal chondrocytes separated and cultured for the 3rd generation in vitro were randomly divided into four groups:control group (all interventions were not applied), simple dynamic pressure group (a dynamic pressure stimulus with a size of 90 mmHg and a frequency of 0.1 Hz was applied using an open pressure control culture system), simple calcium antagonist group (the concentration of 10μmol/L nifedipine was given) and dynamic pressure+calcium antagonist group (a dynamic pressure stimulus with a size of 90 mmHg, frequency of 0.1 Hz and concentration of 10 μmol/L nifedipine were given at the same time). The expression of Sox9 mRNA was detected after 24 h intervention by real-time quantitative polymerase chain reaction (RT-PCR) in four groups. The expression of Sox9 protein was detected by Western blot assay. The intracellular free Ca2+ in metaphyseal chondrocytes was labeled with Fluo-3/AM, and the average fluorescence intensity detected by laser scanning confocal scanning microscopy was compared between four groups. Results The expression of Sox9 mRNA was 3.81 times higher in dynamic stress group than that in the control group, and the protein expression level was 2.33 times higher than that of the control group (P<0.05). There were no significant differences in the expression of Sox9 mRNA and protein between the calcium antagonist group and the control group. The expressions of Sox9 mRNA and protein were lower in dynamic pressure+calcium antagonist group than those in the dynamic stress group, but which were higher than those of control group(P<0.05). The results of average fluorescence intensity showed that there was no significant difference in the intracellular free Ca2+ concentration between four groups (P > 0.05). Conclusion Dynamic stress stimulation can increase the expression of Sox9 mRNA and protein in rat metaphyseal chondrocytes. There is calcium channel involvement in the mechanical signal transduction.
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Flatfoot is a common foot disorder. Some modifications by orthotic shoes for the flatfoot have been prescribed, however their effectivenesses are not fully proven yet. We have tried to validate the effectivenesses of conventional orthotic shoes for the flatfoot patients. We assessed the static and dynamic pressure, dynamic pressure-time integral, and relative impulse with and without wearing orthotic shoes. Thirteen subjects with the flatfoot were included in this study. The results showed the positive effects of orthotic shoes for the subjects. Especially the dynamic pressure-time integral values revealed the significantly reduced values at the medial side of midfoot, which meant the functional improvement of flatfoot status. We have concluded that the use of conventional orthotic shoes for the flat foot patients would be effective for properly selected patients, if there is no other associated abnormality.
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Humanos , Pé Chato , Pé , SapatosRESUMO
The purpose of this study was to measure the foot pressure distribution of normal children. Static and dynamic pressure, dynamic pressure-time integral, relative impulse, static pressure distribution between forefoot and heel, and the percentage of contact time in each phase of the gait cycle were measured from 68 normal children by the in-sole pressure measurement system. The measurements were perfomed while standing and walking with their comfortable speed using the in-sole pressure measurement system. The sites of the greatest static pressure, dynamic pressure-time integral and relative impulse were obtained from the 2nd and the 3rd metatarsal head areas. And the dynamic pressure was obtained from in the lateral heel area. The forefoot to heel load ratio was about 6 to 4 in the static state. The contact time was greatest during the push-off phase.