• Polymer(Korea)
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• v.32 no.6
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• pp.516-522
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• 2008

Biodegradable polymers have been used extensively as scaffolding materials to regenerate new tissues and the ingrowth of tissue have been reported to be dependent directly of the porosity, pore diameter, pore shape, and porous structure of the scaffold. In this study, porous poly (L-lactide-co-glycolide) (PLGA) scaffolds with five different pore sizes were fabricated to investigate the effect of pore sizes for AF tissue regeneration. Cellular viability and proliferation were assayed by MTT test. Hydroxyproline/DNA content of AF cells on each scaffold was measured. sGAG analyses were performed at each time point of 2 and 6 weeks. Scaffold seeded AF cells were implanted into the back of athymic nude mouse to observe the difference of formation of disc-like tissue depending on pore size in vivo. We confirmed that scaffold with $180{\sim}250{\mu}m$ pores displayed high cell viability in vitro and produced higher ECM than scaffold with other pore sizes in vivo.

• Journal of Ginseng Research
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• v.43 no.4
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• pp.580-588
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• 2019

Background: Ginsenoside Rg1 has been shown to clear senescence-associated beta-galactosidase (SA-${\beta}$-gal) in cultured cells. It remains unknown whether Rg1 can influence SA-${\beta}$-gal in exercising human skeletal muscle. Methods: To examine SA-${\beta}$-gal change, 12 young men (age $21{\pm}0.2years$) were enrolled in a randomized double-blind placebo controlled crossover study, under two occasions: placebo (PLA) and Rg1 (5 mg) supplementations 1 h prior to a high-intensity cycling (70% $VO_{2max}$). Muscle samples were collected by multiple biopsies before and after cycling exercise (0 h and 3 h). To avoid potential effect of muscle biopsy on performance assessment, cycling time to exhaustion test (80% $VO_{2max}$) was conducted on another 12 participants (age $23{\pm}0.5years$) with the same experimental design. Results: No changes of SA-${\beta}$-gal were observed after cycling in the PLA trial. On the contrary, nine of the 12 participants showed complete elimination of SA-${\beta}$-gal in exercised muscle after cycling in the Rg1 trial (p < 0.05). Increases in apoptotic DNA fragmentation (PLA: +87% vs. Rg1: +133%, p < 0.05) and $CD68^+$ (PLA:+78% vs. Rg1:+121%, p = 0.17) occurred immediately after cycling in both trials. During the 3-h recovery, reverses in apoptotic nuclei content (PLA:+5% vs. Rg1 -32%, p < 0.01) and increases in inducible nitrate oxide synthase and interleukin 6 mRNA levels of exercised muscle were observed only in the Rg1 trial (p < 0.01). Conclusion: Rg1 supplementation effectively eliminates senescent cells in exercising human skeletal muscle and improves high-intensity endurance performance.

• The korean journal of orthodontics
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• v.23 no.2 s.41
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• pp.229-248
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• 1993

[ $Interferon-\gamma$ ] has been suggested as a cytokine of connective tissue stabilizer. In addition, it has also been demonstrated that this cytokine inhibited bone remodeling activities of the bone derived cells. In order to illuminate the effects of this cytokine in orthodontic force induced bone remodeling, it was administered to primary cultured periodontal ligament cells which have been known to have some osteoblast like characteristics. $Interferon-\gamma$ slightly decreased $[^3H]thymidine$ incorporation rate without a significant change in the total cellular DNA content up to 1000 U/ml, which meant these doses were not cytotoxic to the cell. Total protein synthesis was not influenced by various concentration of interferon-y whether it was determined by the $[^3H]proline$ incorporation rate or by the Lowry smethod. The effect of $interferon-\gamma$ on the individual protein was, however, differential, ie, it increased $[^3H]proline$ incorporation into the noncollagenous protein marginally, while it decreased $[^3H]proline$ incorporation into the collagen, so that it caused dose-dependent suppression of the relative collagen synthesis. On the contrary, the fibronectin synthesis determined by the ELISA was increased by 1000 U/ml of $interferon-\gamma$. The differential effects of the interferon-y on the collagen and fibronectin synthesis exhibited not only their protein level but also the steady state mRNA level. $Interferon-\gamma$ decreased steady state level of ${\alpha}1(I)$ procollagen mRNA significantly, while showing no significant changes in the fibronectin mRNA level. In addition to this, it was also found that indomethacin did not affect on the $interferon-\gamma$ induced collagen decrease in this cell, which meant prostaglandins were not involed in the process of $interferon-\gamma$ induced collagen decrease. So it can be concluded that the incubation of periodontal ligament cells with 1000 U/ml of $interferon-\gamma$ for 24 hr showed differential effects on the type I collagen and fibronectin gene expression. The decrease in relative collagen synthesis in the protein level was related with decrease in the steady state level of mRNA, while the increase in the fibronectin synthesis in the protein level was not correlated with the mRNA level.