Young-Suk Yu

Suppression of protein kinase C-ζ attenuates vascular leakage via prevention of tight junction protein decrease in diabetic retinopathy

To investigate the effect of protein kinase C (PKC)-ζ inhibition on vascular leakage in diabetic retinopathy, streptozotocin-induced diabetic mice were intravitreously injected with siPKC-ζ. According to the fluorescein angiography of the retinal vessels, suppression of PKC-ζ effectively attenuated vascular leakage in diabetic retina. Further evaluation on the retina with western blot analysis and immunohistochemistry revealed accompanying restoration of tight junction proteins on retinal vessels. As two major contributors to vascular leakage in diabetic retinopathy, vascular endothelial growth factor (VEGF) and advanced glycation end products (AGEs) were investigated on the tight junction protein expression in endothelial cells. Inhibition of PKC-ζ attenuated VEGF-induced decrease of tight junction proteins and accompanying hyperpermeability in human retinal microvascular endothelial cells (HRMECs). PKC-ζ inhibition also attenuated AGE-induced decrease of tight junction proteins in HRMECs. Our findings suggest that inhibition of PKC-ζ could be an alternative treatment option for compromised blood-retinal barrier in diabetic retinopathy.

Gene expression profiles of primary retinal pigment epithelial cells from apolipoprotein E knockout and human apolipoprotein E2 transgenic mice

Age-related macular degeneration (AMD) causes visual impairment in the elderly. In non-neovascular AMD, studies involving human subjects have suggested potential involvement of aberrant lipid metabolism. However, there have been no reports on gene expression patterns in animal models of non-neovascular AMD with abnormal lipid metabolism such as apolipoprotein E knockout and human apolipoprotein E2 transgenic mice. Transcriptome analysis was performed using retinal pigment epithelium cells of apoE knockout and apolipoprotein E2 mice using microarray analysis. C57BL/6, Rxrb, Pparbp, Vldlr, and Edf1, which are primarily related to lipid metabolism, were upregulated, while Tgfbr1 and Pdgfb, which are related to pathologic angiogenesis in AMD, were downregulated in both types of mice. Apolipoprotein E knockout and apolipoprotein E2 mice showed characteristic gene expression patterns in the transcriptome analysis of primary retinal pigment epithelium cells. These results suggest that specific genes associated with lipid metabolism and angiogenesis are involved in the pathogenesis and progression of AMD.

A new electrical recording neural probe integrated with chemical stimulation

This paper presents an integrated neural probe that can be used as a neural signal recorder as well as a chemical stimulator. The single unit integrated probe features in-plane shanks with buried microchannels and low impedance microelectrodes. The fabricated neural probe has three 3 mm-long shanks with a 10 /spl mu/m-diameter microchannel and six 30 /spl mu/m /spl times/ 30 /spl mu/m square gold microelectrodes per shank. The measured impedance magnitude and the phase shift of the microelectrodes are 23.1 k/spl Omega//900 /spl mu/m/sup 2/ and 52.9/spl deg/ at 1 kHz, respectively.

Fabrication of a novel 3D 8/spl times/8 electrode array for artificial retina

This paper presents a novel 3D 8/spl times/8 multi-electrode array for artificial retina application. Each electrode features a triangular pyramidal structure that composed of one (111) plane and two vertical planes. The coneangle between the (111) plane and the vertical plane is 19.5/spl deg/. The sharp triangular pyramidal structure makes the minimal invasive penetration for the inner limiting membrane. The characteristic measurement of impedance magnitude and the phase shift of a single electrode are 1.19 M/spl Omega/ and 80.8/spl deg/ at 1 kHz, respectively.