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Jangheung gun, South Korea

Hwang Y.P.,Chungnam National University | Oh K.N.,Natural Resources Research Institute | Yun H.J.,Chungnam National University | Yun H.J.,Chosun University | Jeong H.G.,Chungnam National University
Journal of Dermatological Science | Year: 2011

Background: Ultraviolet (UV) irradiation causes major changes in skin connective tissues as a result of the degradation of collagen, a major structural component of the extracellular matrix. This process is likely mediated by matrix metalloproteinases (MMPs). Such changes in collagenous skin tissues have been suggested to be causes of cutaneous aging and skin cancer. Objective: We investigated the protective effects of apigenin and luteolin on immortalized human keratinocytes (HaCaT) against UVA damage. We then explored the inhibitory effects of apigenin and luteolin on UVA-induced MMP-1 and investigated the molecular mechanism underlying those effects. Methods: HaCaT cells were treated with apigenin and luteolin for the indicated times followed by irradiation with UVA. Those effects were assessed by semi-quantitative PCR, Western blotting and enzymic activity assays. Results: These two compounds, at concentrations of 1-5μM, increased the viability of, and inhibited ROS production in HaCaT cells exposed to UVA irradiation. Pre-treatment of HaCaT cells with apigenin and luteolin also inhibited UVA-induced production of the collagenases MMP-1. They also suppressed UVA-induced expression of c-Jun and c-Fos and the phosphorylation of three MAP kinases, upstream modulators of AP-1. Furthermore, the same two flavonoids decreased the UVA-induced influx of Ca2+ into HaCaT cells and the phosphorylation of Ca2+/calmodulin-dependent kinases (CaMKs). Conclusion: The results indicate that apigenin and luteolin inhibited UVA-induced collagenolytic MMP-1 production by interfering with Ca2+-dependent MAPKs and AP-1 signaling. They may thus be potentially useful in the prevention and treatment of skin photoaging. © 2010 Japanese Society for Investigative Dermatology. Source


Dumke J.D.,University of Minnesota | Hrabik T.R.,University of Minnesota | Brady V.J.,Natural Resources Research Institute | Gran K.B.,University of Minnesota | And 2 more authors.
North American Journal of Fisheries Management | Year: 2010

Large sand bed loads in trout stream headwaters can limit salmonid spawning habitat and reproductive success. This phenomenon has been observed in many northern Wisconsin watersheds, where historic logging practices are the likely source of the sediment loading. Presently, sediment transport is limited by abundant woody debris, causing channels to aggrade and bury gravels. We evaluated the impacts of a wood debris and beaver dam removal remediation strategy on fine sediment transport and exposure of the underlying gravel and cobble substrates in a second-order Lake Superior tributary. A 300-m treatment reach received selective wood removals and was compared with both an upstream 300-m reference reach receiving no alteration and a downstream reach to monitor the effects of transferred fine sediment. Physical channel measurements were taken before the wood removal process, with repeat sampling at 10 and 12 months posttreatment. The wood removal treatment resulted in a significant 25% narrowing of mean stream widths, a 32% increase in mean flow velocities, a 58% reduction in the sand bed load, and a 400% increase in the available coarse substrate across the channel. Grain size distributions coarsened noticeably from pre- to posttreatment. Water depth and temperature were not altered by the treatment, and the reference station physical measures were relatively unchanged over the 12-month study period. Immediately after the wood removal there was an observable pulse of sediment traveling through the downstream reach that increased the sand bed load, increased stream widths, and filled pools. However, these impacts diminished with time, and near-preremoval conditions had returned after 12 months. The wood removal treatment caused a significant reduction in sand content and enhanced the availability of salmonid spawning substrates. © American Fisheries Society 2010. Source


Najafi B.,Islamic Azad University at Marvdasht | Torabi Dastgerduei S.,Natural Resources Research Institute
Journal of Agricultural Science and Technology | Year: 2015

This study was conducted to determine timeliness costs in using machinery and their effects on farmers’ revenues. In addition, optimum cropping pattern was compared with the existing one assuming removal of timeliness cost. For the purpose of the study, mixed integer and linear programming methods were used. The study was conduced in Marvdasht region in southern Iran. The data were collected through interviews with a sample of 80 farm managers. Selected farmers were divided into six groups in terms of farm size and farm machinery use, and in each group a representative farm was selected. Findings of the study showed that 19 percent of farmers owned and 81 percent rented tractor and, as a result, timeliness cost was considerable for the latter group. The results also showed that for the farmers whose farm size was more than 10 hectares, it was justified to buy tractor and rent a combine. The results revealed that there was a gap between the optimum and existing cropping patterns with respect to timeliness cost and gross margin increased mostly in the groups that owned tractor and more than five hectares of land. Finally, in order to minimize timeliness cost, joint ownership of machinery by neighboring farms was recommended. © 2015, Tarbiat Modares University. All rights reserved. Source


Merten E.,University of Minnesota | Finlay J.,University of Minnesota | Johnson L.,Natural Resources Research Institute | Newman R.,University of Minnesota | And 2 more authors.
Water Resources Research | Year: 2010

Natural pieces of wood provide a variety of ecosystem functions in streams including habitat, organic matter retention, increased hyporheic exchange and transient storage, and enhanced hydraulic and geomorphic heterogeneity. Wood mobilization is a critical process in determining the residence time of wood. We documented the characteristics and locations of 865 natural wood pieces (>0.05 m in diameter for a portion >1 m in length) in nine streams along the north shore of Lake Superior in Minnesota. We determined the locations of the pieces again after an overbank stormflow event to determine the factors that influenced mobilization of stationary wood pieces in natural streams. Seven of 11 potential predictor variables were identified with multiple logistic regression as significant to mobilization: burial, effective depth, ratio of piece length to effective stream width (length ratio), bracing, rootwad presence, downstream force ratio, and draft ratio. The final model (P < 0.001, r2 = 0.39) indicated that wood mobilization under natural conditions is a complex function of both mechanical factors (burial, length ratio, bracing, rootwad presence, draft ratio) and hydraulic factors (effective depth, downstream force ratio). If stable pieces are a goal for stream management then features such as partial burial, low effective depth, high length relative to channel width, bracing against other objects (e.g., stream banks, trees, rocks, or larger wood pieces), and rootwads are desirable. Using the model equation from this study, stewards of natural resources can better manage in-stream wood for the benefit of stream ecosystems. Copyright 2010 by the American Geophysical Union. Source


Kwon H.-J.,Korea Research Institute of Bioscience and Biotechnology | Kwon H.-J.,Seoul National University | Won Y.-S.,Korea Research Institute of Bioscience and Biotechnology | Yoon Y.-D.,Natural Resources Research Institute | And 5 more authors.
Journal of Hepatology | Year: 2011

Background & Aims: Liver regeneration is a complicated process involving a variety of interacting factors. Vitamin D3 up-regulated protein 1 (VDUP1) is a potent growth suppressor that, upon over-expression, inhibits tumor cell proliferation and cell-cycle progression. Here, we investigated the function of VDUP1 in liver regeneration following hepatectomy in mice. Methods: Liver regeneration after 70% partial hepatectomy (PH) was compared in VDUP1 knockout (KO) and wild-type (WT) mice, and the activities of proliferative- and cell-cycle-related signaling pathways were measured. Results: Compared with WT mice, liver recovery was significantly accelerated in VDUP1 KO mice during the first day after PH, in association with increased DNA synthesis. Consistent with this observation, the expression levels of key cell-cycle regulatory proteins, including cyclin D, cyclin E, cyclin-dependent kinase 4 (CDK4), p21, and p27, were markedly altered in the livers of VDUP1 KO mice. Induction of growth factors and activation of proliferative signaling pathway components including extracellular signal-regulated kinase 1/2 (ERK1/2), Akt, glycogen synthase kinase 3β (GSK3β), mammalian target of rapamycin (mTOR), and p70S6 kinase (p70S6K), occurred much earlier and to a greater extent in VDUP1 KO mouse livers. In addition, primary hepatocytes isolated from VDUP1 KO mice displayed increased activation of ERK1/2 and Akt in response to HGF and TGF-α. Conclusions: Our results reveal an important role for VDUP1 in the regulation of proliferative signaling during liver regeneration. Altered activation of genes involved in ERK1/2 and Akt signaling pathways may explain the accelerated growth responses seen in VDUP1 KO mice. © 2010 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved. Source

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