Compressive force has been found to be catabolic to alveolar bone during orthodontic tooth movement. This study quantified the fusion of mononuclear RAW 264.7 cells (a murine osteoclastic-like cell ...line) into multinucleated osteoclasts under a hydrostatic pressure-generated mechanical compression-the new model of various magnitudes and durations.
RAW 264.7 cells were subjected to 0.3, 0.6 or 0.9 g/cm
of compressive force by an acrylic cylinder custom-made by laser cutting or no compressive force for 4 days during osteoclastogenic induction. TRAP-positive multinucleated cells were quantified. For the release from force experiment, osteoclastogenesis was induced by 0.6 g/cm
mechanical stimuli for 0, 1, 2, 3 or 4 days. Cell viability, TRAP-positive multinucleated cells,
and Cathepsin K (
) gene expression were evaluated 4 days after release from force.
Compressive force at 0.6 and 0.9 g/cm
significantly increase the number of TRAP-positive multinucleated cells (
< 0.05). Release from continuous mechanical compression after 4 days significantly elevated the number of TRAP-positive multinucleated cells and
and
mRNA expression, with no adverse effects on cell viability (
< 0.05).
Continuous stimulation with compressive force induced osteoclastogenesis in RAW 264.7 cells by enhancing
and
expression, which provides new understanding of bone remodeling during orthodontic treatment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Compressive force has been found to be catabolic to alveolar bone during orthodontic tooth movement. This study quantified the fusion of mononuclear RAW 264.7 cells (a murine osteoclastic-like cell ...line) into multinucleated osteoclasts under a hydrostatic pressure-generated mechanical compression-the new model of various magnitudes and durations.
RAW 264.7 cells were subjected to 0.3, 0.6 or 0.9 g/cm2 of compressive force by an acrylic cylinder custom-made by laser cutting or no compressive force for 4 days during osteoclastogenic induction. TRAP-positive multinucleated cells were quantified. For the release from force experiment, osteoclastogenesis was induced by 0.6 g/cm2 mechanical stimuli for 0, 1, 2, 3 or 4 days. Cell viability, TRAP-positive multinucleated cells, DCSTAMP and Cathepsin K (CTSK) gene expression were evaluated 4 days after release from force.
Compressive force at 0.6 and 0.9 g/cm2 significantly increase the number of TRAP-positive multinucleated cells (P < 0.05). Release from continuous mechanical compression after 4 days significantly elevated the number of TRAP-positive multinucleated cells and DCSTAMP and CTSK mRNA expression, with no adverse effects on cell viability (P < 0.05).
Continuous stimulation with compressive force induced osteoclastogenesis in RAW 264.7 cells by enhancing DCSTAMP and CTSK expression, which provides new understanding of bone remodeling during orthodontic treatment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
To investigate the effects of compressive force and/or mechanical vibration on NFATc1, DCSTAMP, and CTSK (cathepsin K) gene expression and the number of tartrate-resistant acid phosphatase ...(TRAP)-positive multinucleated cells in RAW 264.7 cells, a murine osteoclastic-like cell line.
RAW 264.7 cells were subjected to mechanical vibration, compressive force, or compressive force combined with vibration. Cell viability and the numbers of TRAP-positive multinucleated cells were evaluated. NFATc1, DCSTAMP, and CTSK gene expressions were analyzed using real-time quantitative reverse transcription polymerase chain reaction.
Compressive force combined with mechanical vibration significantly increased the numbers of TRAP-positive multinucleated cells but did not significantly affect cell viability. In addition, compressive force combined with mechanical vibration significantly increased NFATc1, DCSTAMP, and CTSK mRNA expression compared with compressive force or vibration alone.
Compressive force combined with mechanical vibration induces osteoclastogenesis and upregulates NFATc1, DCSTAMP, and CTSK gene expression in RAW 264.7 cells. These results provide more insight into the mechanisms by which vibratory force accelerates orthodontic tooth movement.
To address the imbalance in the supply of grass resources caused by seasonality and regional factors, it is crucial to efficiently store and transport alfalfa. Exploring suitable grass feed ...processing techniques contributes to the stable transportation of grass blocks and long-term storage of nutritional components. The Central Composite Design response surface design was used to design experiments, with moisture content and compressive force as the test factors. Based on the experimental results, it was found that lower moisture content and a certain compressive force were beneficial for the stability, high density, and protein storage of alfalfa blocks. The microscopic examination of alfalfa particles revealed that a certain moisture content (15%) facilitates the formation of solid bridges between particles, leading to more stable alfalfa blocks. The final optimized process parameters were moisture content of 14.3% and compressive force of 34.8 kN. Under these conditions, the density of the molded alfalfa block was 1001 kg/m3, with R-CP at 96.96%, R-EE at 67.23%, and R-CF at 114.13%.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
•One-dimensional multi-field coupling model of axially compressed PS rods incorporating the surface effect is developed.•The analytical solutions for critical dynamic buckling loads and damped ...resonance frequencies of axially compressed PS nano-rod are presented.•The surface effect has a significant effect on macroscopic multi-field coupling behaviors of PS rods at nanoscale.
Many rod- and fiber-based semiconductor devices operate in the state of compression due to the external mechanical force or the inner temperature change, which not only causes the static buckling but also plays a significant role in the dynamic buckling as well as resonance frequencies. We study the dynamic buckling and free bending vibration of an axially compressed simply supported piezoelectric semiconductor (PS) rod at the nanoscale with open-circuit and electrically isolated boundary conditions. The one-dimensional basic equations incorporating the surface effect are presented based on the classical theory of Gurtin-Muduch surface elasticity. The analytical expressions of critical dynamic buckling loads and damped resonance frequencies of the axially compressed PS rod are obtained. The influences of surface effect on the critical dynamic buckling loads and damped resonance frequencies of the PS rod are investigated in detail. The effects of axial compressive force and initial electron concentration on the effective damping ratio of the vibrating PS rod are also studied. Numerical results show that the surface effect remarkably enhances both the critical buckling loads and damped resonance frequencies of the axially compressed PS rod at nanoscale, at the same time the damped resonance frequency shift is linearly dependent on the compressive force.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Introduction: Manual Material handling includes activities in which pushing, pulling, lifting, lowering, carrying, and holding the load, the most common of which is lifting. This study aimed to ...evaluate the reliability of the KIM-LHC method to identify high-risk manual load lifting tasks.
Material and Methods: This cross-sectional study was performed on healthy male workers with a history of manual material handling in a laboratory setting. The sample size was determined according to previous studies of 15 people. The participants were required to perform 25 tasks with four iterations randomly. An inclinometer device was used to determine the forward bending angle at the waist. Compression loads exerted on L5/S1 were estimated using 3DSSPP software using participants' postural and anthropometric information. Also, the tasks were evaluated using the KIM-LHC method, and their final scores and levels of MSD risks were determined. Data were analyzed using SPSS.20 software and the Chi-square test.
Results: The results of compression load estimation for lifting tasks showed that 92% of the tasks had a low-risk level (less than 3400 N), and 8% of the tasks had a medium-risk level (3400 to 6800 N). While the results of the KIM-LHC method showed that 28% of tasks had a low-risk level, 64% had a medium level, and 8% had a high-risk level.
Conclusion: The results of this study showed no correlation between the risk levels of the KIM-LHC method and the estimated compression load for some designed lifting tasks. Therefore, there is a possibility of error in estimating the risk level of some lifting tasks by the KIM-LHC method, and more biomechanical studies should be performed on kinetics and kinematics.
Orthodontic tooth movement (OTM) is initiated by mechanical force and featured as alveolar bone remodeling. Periodontal ligament cells (PDLCs) are one of the major cell components in periodontium and ...responsible for the signal transduction during OTM. Up to now, the mechanical stress-induced genetic alteration and mechanotransduction mechanisms in PDLCs still remain not fully understood. In this study, we identified a novel compressive force responsive gene, Growth differentiation factor 15 (GDF15), whose expression transcriptionally increased in human periodontal ligament cells (PDLCs) after exposure to the static compressive force in vitro. Functional analyses proved that GDF15 could promote osteoclast differentiation of the murine macrophage cell line RAW264.7 cells. Molecular investigation uncovered that GDF15 could promote the expression of several pro-inflammatory cytokines and RANKL/OPG ratio in PDLCs, while knockdown of GDF15 impaired their upregulation induced by compressive force. Additionally, administration of recombinant GDF15 protein stimulated the M1-like polarization of RAW264.7 cells and THP-1 induced macrophages. Mechanistically, siRNA-mediated suppression of GDF15 significantly disrupted the nuclear translocation of NF-κB and ERK phosphorylation in response to compressive force. Finally, Yes-associated protein (YAP) was demonstrated to be the upstream regulator of GDF15 in human PDLCs, implying a force-induced YAP-GDF15 regulation mechanism. Overall, these data suggested important roles of GDF15 in the functional modulation of both PDLCs and osteoclast progenitors in response to compressive force, providing novel insights into the molecular mechanism of mechanotransduction during OTM process.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This study aimed to investigate the biological roles and mechanisms of compressive force-stimulated periodontal ligament fibroblasts (PDLFs) on polarization of macrophages
PDLFs were stimulated with ...or without static compressive force, and then conditioned medium, high-molecular weight proteins and low-molecular weight proteins were collected to treat THP-1 macrophages. RT-qPCR and flow cytometric analysis were used to evaluate the polarization of macrophages. Exosomes were isolated by ultracentrifugation method and identified via transmission electron microscopy, western-blot and nano-tracking analysis. The protein level of Yes-Associated Protein (YAP) contained in exosomes was detected by western blot. GW4869 and Verteporfin were used to inhibit exosome secretion and YAP- TEA domain transcription factor (TEAD) interaction respectively.
Exosomes were successfully purified from PDLFs and could be efficiently incorporated into THP-1 macrophages. conditioned medium, HMW proteins and exosomes derived from compressive force-treated PDLFs significantly induce M1 polarization of macrophages. While inhibiting exosomes secretion by GW4869 treatment eliminated the inductive effect. YAP target genes, connective tissue growth factor (CTGF) and cysteine-rich angiogenic inducer 61 (CYR61) were upregulated in macrophages when treated with exosomes derived from compressive force-treated PDLFs (F-Exo). YAP level was elevated in the F-Exo. When macrophages were treated with Verteporfin, expression of YAP target genes and M1 polarization were significantly downregulated.
These results suggested that exosomes derived from compressive force-treated PDLFs promoted the M1 polarization of the THP-1 macrophages. The elevated level of YAP in the exosomes may be a critical factor for this response.
•Compressive force decreases exosome secretion by periodontal ligament fibroblasts.•Periodontal ligament fibroblasts promote macrophage M1 polarization via exosomes.•Exosomes activate M1 polarization by upregulating Yes-Associated Protein.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
ABSTRACT
Purpose
Tibial bone stress injuries are a common overuse injury among runners and military cadets. Current treatment involves wearing an orthopedic walking boot for 3 to 12 wk, which limits ...ankle motion and leads to lower limb muscle atrophy. A dynamic ankle orthosis (DAO) was designed to provide a distractive force that offloads in-shoe vertical force and retains sagittal ankle motion during walking. It remains unclear how tibial compressive force is altered by the DAO. This study compared tibial compressive force and ankle motion during walking between the DAO and an orthopedic walking boot.
Methods
Twenty young adults walked on an instrumented treadmill at 1.0 m·s
−1
in two brace conditions: DAO and walking boot. Three-dimensional kinematic, ground reaction forces, and in-shoe vertical force data were collected to calculate peak tibial compressive force. Paired
t
-tests and Cohen’s
d
effect sizes were used to assess mean differences between conditions.
Results
Peak tibial compressive force (
P
= 0.023;
d
= 0.5) and Achilles tendon force (
P
= 0.017;
d
= 0.5) were moderately lower in the DAO compared with the walking boot. Sagittal ankle excursion was 54.9% greater in the DAO compared with the walking boot (
P
= 0.05;
d
= 3.1).
Conclusions
The findings from this study indicated that the DAO moderately reduced tibial compressive force and Achilles tendon force and allowed more sagittal ankle excursion during treadmill walking compared with an orthopedic walking boot.
•Cylindrical columns were experimentally investigated in compression.•Analyses of the shapes of buckled columns were carried out.•The studies used non-classical operational calculus.•The shapes of ...the column were determined in the form of modulated harmonic signals.•The created models describe relations between compressive force and column deflection.
Analyses were carried out on glass-fibre-reinforced polymer tube columns with reference to laboratory tests. The angles of the glass fibre beams were 20°, 55° and 85°. The study employed non-classical operational calculus. Various modulated harmonic signal shapes were considered for columns and tubes at buckling. The buckling loads were assessed and compared for different models.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
