The in vitro effects of dehydroepiandrosterone on human osteoarthritic chondrocytes

AbstractObjective: To investigate the in vitro effects of dehydroepiandrosterone (DHEA) on human osteoarthritic chondrocytes.Design: Chondrocytes isolated from human osteoarthritic knee cartilage were three-dimensionally cultured in alginate beads, except for cell proliferation experiment. Cells were treated with DHEA in the presence or absence of IL-1β. The effects on chondrocytes were analyzed using a 3-(4,5-dimethylthiazol-2yl)-5-(3-carboxymethoxy-phenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt (MTS) assay (for chondrocyte proliferation), a dimethylmethylene blue (DMB) assay (for glycosaminoglycan (GAG) synthesis), and an indole assay (for DNA amount). Gene expressions of type I and II collagen, metalloproteinase-1 and -3 (MMP-1 and -3), and tissue inhibitor of metalloproteinase-1 (TIMP-1) as well as the IL-1β-induced gene expressions of MMP-1 and -3 were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). The protein synthesis of MMP-1 and -3 and TIMP-1 was determined by Western blotting.Results: The treatment of chondrocytes with DHEA did not affect chondrocyte proliferation or GAG synthesis up to 100μM of concentration. The gene expression of type II collagen increased in a dose-dependent manner, while that of type I decreased. DHEA suppressed the expression of MMP-1 significantly at concentrations exceeding 50μM. The gene expression of MMP-3 was also suppressed, but this was without statistical significance. The expression of TIMP-1 was significantly increased by DHEA at concentrations exceeding 10μM. The effects of DHEA on the gene expressions of MMP-1 and -3 were more prominent in the presence of IL-1β, in which DHEA suppressed not only MMP-1, but also MMP-3 at the lower concentrations, 10 and 50μM, respectively. Western blotting results were in agreement with RT-PCR, which indicates that DHEA acts at the gene transcription level.Conclusions: Our study demonstrates that DHEA has no toxic effect on chondrocytes up to 100μM of concentration and has an ability to modulate the imbalance between MMPs and TIMP-1 during OA at the transcription level, which suggest that it has a protective role against articular cartilage loss

Low energy fast events from radon progenies at the surface of a CsI(Tl) scintillator

In searches for rare phenomena such as elastic scattering of dark matter particles or neutrinoless double beta decay, alpha decays of Rn222 progenies attached to the surfaces of the detection material have been identified as a serious source of background. In measurements with CsI(Tl) scintillator crystals, we demonstrate that alpha decays of surface contaminants produce fast signals with a characteristic mean-time distribution that is distinct from those of neutron- and gamma-induced events.Comment: 9 pages, 8 figure

Strategies for Controlled Placement of Nanoscale Building Blocks

The capability of placing individual nanoscale building blocks on exact substrate locations in a controlled manner is one of the key requirements to realize future electronic, optical, and magnetic devices and sensors that are composed of such blocks. This article reviews some important advances in the strategies for controlled placement of nanoscale building blocks. In particular, we will overview template assisted placement that utilizes physical, molecular, or electrostatic templates, DNA-programmed assembly, placement using dielectrophoresis, approaches for non-close-packed assembly of spherical particles, and recent development of focused placement schemes including electrostatic funneling, focused placement via molecular gradient patterns, electrodynamic focusing of charged aerosols, and others

Growth, feeding and ecological roles of the mixotrophic and heterotrophic dinoflagellates in marine planktonic food webs

Planktonic mixotrophic and heterotrophic dinoflagellates are ubiquitous protists and often abundant in marine environments. Recently many phototrophic dinoflagellate species have been revealed to be mixotrophic organisms and also it is suggested that most dinoflagellates may be mixotrophic or heterotrophic protists. The mixotrophic and heterotrophic dinoflagellates are able to feed on diverse prey items including bacteria, picoeukaryotes, nanoflagellates, diatoms, other dinoflagellates, heterotrophic protists, and metazoans due to their diverse feeding mechanisms. In turn they are ingested by many kinds of predators. Thus, the roles of the dinoflagellates in marine planktonic food webs are very diverse. The present paper reviewed the kind of prey which mixotrophic and heterotrophic dinoflagellates are able to feed on, feeding mechanisms, growth and ingestion rates of dinoflagellates, grazing impact by dinoflagellate predators on natural prey populations, predators on dinoflagellates, and red tides dominated by dinoflagellates. Based on this information, we suggested a new marine planktonic food web focusing on mixotrophic and heterotrophic dinoflagellates and provided an insight on the roles of dinoflagellates in the food web. © 2010 Korea Ocean Research & Development Institute (KORDI) and the Korean Society of Oceanography (KSO) and Springer Netherlands.Y

Dominant mechanisms of the sintering of copper nano-powders depending on the crystal misalignment

Sintering mechanisms of nanoscale copper powder are investigated using molecular dynamics ( MD) simulations based on the embedded-atom method (EAM). The densification parameters, such as shrinkage, and relative sintered density are calculated using the two-particle sintering model. This paper considers the important role of crystalline misalignment between two particles on densification. Besides volume diffusion contribution, misalignment between the crystal structures results in enhanced grain boundary diffusion. At low temperatures, grain boundary torque cause particles to rotate to reduce grain boundary energy. At higher temperatures, particle rotation becomes complicated including remarkable twist, and grain boundary tilting due to grain-boundary-like diffusion. These results provide insights to the processing cycle parameters applicable to nano-powders. (C) 2016 Elsevier B.V. All rights reserved.111sciescopu

Development of surface water exposure scenarios for risk assessment of pesticides in Korea

Surface water exposure scenarios used in the risk assessment of Korea's aquatic ecosystems, were developed to represent the 90th percentile pesticide exposure situation as a part of the country's pesticide registration procedure. The scenarios are used to estimate the pesticide concentration in the water of a rice paddy and small streams for three protection goals: (i) mudfish in rice paddies, (ii) the aquatic ecosystem of small streams located near rice paddies, and (iii) the aquatic ecosystem of small streams located near fruit orchards. The scenarios were derived taking into account major exposure routes, such as spray drift, runoff, and drainage. The scenarios were parameterized for appropriate models including the pesticide root zone model (PRZM) and the toxic substances in surface waters model (TOXSWA). A total of 17 pesticide compounds and 28 formulated products were selected to test the risk assessment using the developed scenarios. The simulated predicted environmental concentrations (PECs) fully reflected a) the exposure routes for each protection goal b) the use patterns of the products c) physicochemical properties of the pesticides, and d) meteorological conditions of Korea. However, while assessing the risks for aquatic organisms we observed that for most of the selected pesticides the calculated exposure concentrations were higher than the regulatory acceptable concentration (RAC). To implement the exposure scenarios and models for pesticide authorization in Korea, further research on the RACs is needed. We also recommend studies to develop a higher-tier model and risk-mitigation measures that can be applied to the Korean situation.</p