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350 results on '"Park, H.C."'

21. Postobstructive regeneration of kidney is derailed when surge in renal stem cells during course of unilateral ureteral obstruction is halted

Author

Park, H.C., Yasuda, K., Ratliff, B., Stoessel, A., Sharkovska, Y., Yamamoto, I., Jasmin, J.-F., Bachmann, S., Lisanti, M.P., Chander, P., and Goligorsky, M.S.

Subjects
Caveolins -- Physiological aspects, Caveolins -- Research, Stem cells -- Physiological aspects, Stem cells -- Research, Ureters -- Obstructions, Ureters -- Risk factors, Ureters -- Research, Biological sciences
Abstract

Unilateral ureteral obstruction (UUO), a model of tubulointerstitial scarring (TIS), has a propensity toward regeneration of renal parenchyma after release of obstruction (RUUO). No information exists on the contribution of stem cells to this process. We performed UUO in FVB/N mice, reversed it after 10 days, and examined kidneys 3 wk after RUUO. UUO resulted in attenuation of renal parenchyma. FACS analysis of endothelial progenitor (EPC), mesenchymal stem (MSC) and hematopoietic stem (HSC) cells obtained from UUO kidneys by collagenase-dispersed single-cell suspension showed significant increase in EPC, MSC, and HSC compared with control. After RUUO cortical parenchyma was nearly restored, and TIS score improved by 3 wk. This reversal process was associated with return of stem cells toward baseline level. When animals were chronically treated with nitric oxide synthase (NOS) inhibitor at a dose that did not induce hypertension but resulted in endothelial dysfunction, TIS scores were not different from control UUO, but EPC number in the kidney decreased significantly; however, parenchymal regeneration in these mice was similar to control. Blockade of CXCR4-mediated engraftment resulted in dramatic worsening of UUO and RUUO. Similar results were obtained in caveolin-1-deficient but not -overexpressing mice, reflecting the fact that activation of CXCR4 occurs in caveolae. The present data show increase in EPC, HSC, and MSC population during UUO and a tendency for these cells to decrease to control level during RUUO. These processes are minimally affected by chronic NOS inhibition. Blockade of CXCR4-stromal cell-derived factor-1 (SDF-1) interaction by AMD3100 or caveolin-1 deficiency significantly reduced the UUO-associated surge in stem cells and prevented parenchymal regeneration after RUUO. We conclude that the surge in stem cell accumulation during UUO is a prerequisite for regeneration of renal parenchyma. fibrosis; caveolin; AMD3100; mesenchymal stem cells doi: 10.1152/ajprenal.00542.2009

Published
2010

35. Analysis and design of the Doherty amplifier based on class F and inverse class F amplifiers

Author

Yao, Xi, Jung, S.C., Kim, M.S., Van, J.H., Cho, H., Kwon, S.W., Jeong, J.H., Lim, K.H., Park, C.S., Yang, Y, and Park, H.C.

Subjects
Microwave amplifiers -- Research, Power amplifiers -- Research, Business, Electronics and electrical industries, Engineering and manufacturing industries, Telecommunications industry
Abstract

A Doherty amplifier using class F and inverse class F amplifiers is designed. The amplifier achieved 50.9% efficiency using the two-tone test and 45.2% using the WCDMA test.

Published
2010

45. Mechanically driven spin-orbit-active weak links

Author

Jonson, M., Shekhter, R.I., Entin-Wohlman, O., Aharony, A., Park, H.C., and Radić, D.

Subjects
spin-active weak links, electronic spin current, Електронні властивості низьковимірних систем, Condensed Matter::Strongly Correlated Electrons
Abstract

We show that new functionality of spin-orbit-active electronic weak links can be achieved by their timedependent mechanical deformation. As an illustration we use a simple model to calculate the electronic spin current generated by rotating a bent spin-orbit-active nanowire coupled to bulk metallic leads. Обговорюються нові функціональні можливості, що реалізовуються у тунельних структурах завдяки залежній від часу сильній спін-орбітальній взаємодії електронів. Як приклад запропоновано просту модель, в якій передбачено генерацію спінового струму, що виникає при обертанні зігнутого дроту, який з’єднує два масивні метали, із локалізованою на ній сильною спін-орбітальною взаємодією електронів. Обсуждаются новые функциональные возможности, реализующиеся в туннельных структурах благодаря зависящему от времени сильному спин-орбитальному взаимодействию электронов. В качестве примера предложена простая модель, в которой предсказана генерация спинового тока, возникающая при вращении изогнутой проволоки, соединяющей два массивных металла, с локализованным на ней сильным спинорбитальным взаимодействием электронов.

Published
2018

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