Browsing by Author "Hu, Chao-Kai"

Now showing 1 - 3 of 3

A Microfabricated Coil for Implantable Applications of Magnetic Spinal Cord Stimulation
(2015)
Fu, Yu-Min
;
Chen, Che-Yu
;
Qian, Xin-Hong
;
Cheng, Yu-Ting
;
Wu, Chung-Yu
In this paper, a microfabricated inductive coil comprising of 125-turn coil windings and a MnZn-based magnetic core in a volume of 200 mm(3) is presented for the magnetic neural stimulation in a spinal cord. The coil winding with the parallel-linkage design instead of the typical serial-linkage one is proposed not only to provide better design flexibility to the current mode driving circuit but also to simplify the fabrication process of the 3-D inductive coil, which can further advance the coil miniaturization. Experimental results show the microcoil with a 1.5 A, 1 kHz square-wave current input can induce a voltages of 220 mu V on the conducting wire with an impedance of similar to 0.2 Omega @ kHz, 1 mm separation.
Dose-dependent regulation of cell proliferation and collagen degradation by estradiol on ligamentum flavum
(2014-07-15)
Chen, Mei-Hsiu
;
Hu, Chao-Kai
;
Chen, Pei-Ru
;
Chen, Yu-Shan
;
Sun, Jui-Sheng
Background: Estradiol plays an important role in the regulation of collagen metabolism. Deficiency of estradiol has been reported to be associated with the degeneration of many connective tissues. However, the association of estradiol and hypertrophy of the ligamentum flavum was seldom explored. Therefore, we studied the effects of estradiol on cultured cells from the ligamentum flavum. Methods: Primary cultures of human ligamentum flavum cells obtained from surgical specimens of 14 patients undergoing spinal surgery were used to investigate the effect of estradiol on cell proliferation and the expression of collagen, elastin, and matrix metalloproteinases. Downstream pathways of estrogen receptor underlying the regulation of metalloproteinases were also investigated. Results: In our study, we revealed the existence of estrogen receptors on both female and male ligamentum flavum cells with a gender difference. 17 beta-estradiol increased early (24 hours) proliferation of ligamentum flavum cells in a dose dependent manner and the effect could not be seen when the cell density increased. Estradiol with a concentration of 10-9 M decreased collagen levels and increased the expression of MMP-13. Adding an antagonist of PI3K downstream pathway could reverse the expression of MMP-13 caused by estradiol. Conclusions: The results implied estradiol regulated the expression of MMP-13 via PI3K pathway and contributed to the homeostasis of extracellular matrix in the ligamentum flavum.
Midline Lumbar Fusion Using Cortical Bone Trajectory Screws for Elderly Patients
(2019-03-01)
Hu, Chao-Kai
;
Chen, Shiu-Jau
;
Lin, Jui-Feng
;
Wu, Chung-Yu
;
Tsai, Cheng-Chia
Background: Midline lumbar fusion (MIDLF) using cortical bone trajectory (CBT) is an alternative method of lumbar spinal fusion. It is useful for reduction not only for approach-related morbidity but also for osteoporosis. This study aimed to present our experience with MIDLF, and focused on survey of postoperative wound pain intensity and outcome assessment. Methods: We retrospectively collected patients who met criteria of elderly (age more than 65 years old), spondylolisthesis, disc herniation, or spinal stenosis, and those who received MIDLF operation. By reviewing medical records, we analysed pain scores, complication rates, and screws loosening. Results: Between January 2016 and June 2017, 23 patients were enrolled. One patient had screw malposition who needed reoperation. The rest patients showed significant improvement of the leading symptom. The visual analogue scale (VAS) scores for wound pain on the first postoperative day, second postoperative day, and before discharge were 3.4, 2.3, and 1.4, respectively. Early ambulation was achieved owing to the mild postoperative pain. The mean VAS scores for lower back and leg pain improvement were 4.7 and 4.5 respectively in the 3-month follow-up. At the most recent follow-up, all the patients reported maintenance of the satisfactory result. No screw-loosening or other complications were noted. Conclusions: In our experience, MIDLF using CBT route seemed to reduce post-op wound pain significantly, so that elderly patients could ambulate earlier. It also had less screws loosening, especially for elderly or osteoporotic patients. Copyright (C) 2019, Taiwan Society of Geriatric Emergency & Critical Care Medicine.