John Park

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Ability of mini-implant-facilitated micro-osteoperforations to accelerate tooth movement in rats

American journal of orthodontics and dentofacial orthopedics : official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics, 2016

Although current techniques for accelerated tooth movement often involve invasive surgical proced... more Although current techniques for accelerated tooth movement often involve invasive surgical procedures, micro-osteoperforations (MOPs) using mini-implants may facilitate orthodontic tooth movement without raising flaps, reduce surgical risks, and increase patient acceptance. In this study, we evaluated the effectiveness of mini-implant-facilitated MOPs in inducing accelerated tooth movement and investigated the potential risks for root resorption. Five MOPs were placed on the left side around the maxillary first molars in 6 rats using an automated mini-implant driver, whereas the right side received no MOPs as the control. Closed-coiled springs were secured from incisors to first molars for orthodontic tooth movement. Tooth movement was measured, and samples underwent radiologic and histologic analyses. The MOP side exhibited a 1.86-fold increase in the rate of tooth movement with decreased bone density and bone volume around the first molars compared with the control side. Hematoxyl...

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Pharmacokinetics and osteogenic potential of PEGylated NELL-1 in vivo after systemic administration

by John Park and Charles soonchul Lee

Biomaterials, 2015

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Pharmacokinetics and osteogenic potential of PEGylated NELL-1 in vivo after systemic administration

by Eric Chen, Yulong Zhang, Jia Shen, Chirag Chawan, Benjamin Wu, and John Park

Osteoporosis is a skeletal disorder attributable to an imbalance in osteoblast and osteoclast act... more Osteoporosis is a skeletal disorder attributable to an imbalance in osteoblast and osteoclast activity. NELL-1, a secretory protein that promotes osteogenesis while suppressing osteoclastic activity, holds potential as an osteoporosis therapy. Recently, we demonstrated that PEGylation of NELL-1 significantly improves its thermostability while preserving its bioactivity in vitro. However, the effect of PEGylation on the pharmacokinetics and osteogenic potential of NELL-1 in vivo have yet to be investigated. The present study demonstrated that PEGylation of NELL-1 significantly increases the elimination half-life time of the protein from 5.5 h to 15.5 h while distributing more than 2e3 times the amount of protein to bone tissues (femur, tibia, vertebrae, calvaria) in vivo when compared to naked NELL-1. In addition, microCT and DXA analyses demonstrated that systemic NELL-PEG therapy administered every 4 or 7 days significantly increases not only femoral and lumbar BMD and percent bone volume, but also new bone formation throughout the overall skeleton after four weeks of treatment. Furthermore, immunohisto-chemistry revealed increased osteocalcin expression, while TRAP staining showed reduced osteoclast numbers in NELL-PEG groups. Our findings suggest that the PEGylation technique presents a viable and promising approach to further develop NELL-1 into an effective systemic therapeutic for the treatment of osteoporosis.

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Ability of mini-implant-facilitated micro-osteoperforations to accelerate tooth movement in rats

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Pharmacokinetics and osteogenic potential of PEGylated NELL-1 in vivo after systemic administration

by John Park and Charles soonchul Lee

Biomaterials, 2015

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Pharmacokinetics and osteogenic potential of PEGylated NELL-1 in vivo after systemic administration

by Eric Chen, Yulong Zhang, Jia Shen, Chirag Chawan, Benjamin Wu, and John Park

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