Showing papers by "Pusan National University published in 2006"
TL;DR: In this article, the influence of polymer regioregularity (RR) on the molecular nanostructure, and hence on the resulting material properties and device performance has been investigated, which can be attributed to enhanced optical absorption and transport resulting from the organization of P3HT chains and domains.
Abstract: Low-cost photovoltaic energy conversion using conjugated molecular materials has become increasingly feasible through the development of organic ‘bulk heterojunction (BHJ)’ structures1,2,3,4,5,6,7, where efficient light-induced charge separation is enabled by a large-area donor–acceptor interface2,3. The highest efficiencies have been achieved using blends of poly(3-hexylthiophene) (P3HT) and a fullerene derivative8,9,10,11,12, but performance depends critically on the material properties and processing conditions. This variability is believed to be influenced by the self-organizing properties of P3HT, which means that both optical13,14 and electronic15,16 properties are sensitive to the molecular packing. However, the relationship between molecular nanostructure, optoelectronic properties of the blend material and device performance has not yet been demonstrated. Here we focus on the influence of polymer regioregularity (RR) on the molecular nanostructure, and hence on the resulting material properties and device performance. We find a strong influence of RR on solar-cell performance, which can be attributed to enhanced optical absorption and transport resulting from the organization of P3HT chains and domains. Further optimization of devices using the highest RR material resulted in a power conversion efficiency of 4.4%, even without optimization of electrodes7.
2,268 citations
TL;DR: In this paper, an optical spacer between the active layer and the Al electrode is proposed to redistribute the light intensity inside the device by introducing an optical sensor. But the spacer is not suitable for the case of thin-film photovoltaic cells.
Abstract: reported under AM1.5 (AM: air mass) illumination, this efficiency is not sufficient to meet realistic specifications for commercialization. The need to improve the light-to-electricity conversion efficiency requires the implementation of new materials and the exploration of new device architectures. Polymer-based photovoltaic cells are thin-film devices fabricated in the metal-insulator-metal configuration sketched in Figure 1a. The absorbing and charge-separating bulk-heterojunction layer with a thickness of approximately 100 nm is sandwiched between two charge-selective electrodes; a transparent bilayer electrode comprising poly(3,4-ethylenedioxylenethiophene):polystyrene sulfonic acid (PEDOT:PSS) on indium tin oxide (ITO) glass for collecting the holes and a lower-work-function metal (here, Al) for collecting the electrons. The work-function difference between the two electrodes provides a built-in potential that breaks the symmetry, thereby providing a driving force for the photogenerated electrons and holes toward their respective electrodes. Because of optical interference between the incident (from the ITO side) and back-reflected light, the intensity of the light is zero at the metallic (Al) electrode; Figure 1a shows a schematic representation of the spatial distribution of the squared optical electric-field strength. [9–11] Thus, a relatively large fraction of the active layer is in a dead-zone in which the photogeneration of carriers is significantly reduced. Moreover, this effect causes more electron–hole pairs to be produced near the ITO/PEDOT:PSS electrode, a distribution which is known to reduce the photovoltaic conversion efficiency. [12,13] This “optical interference effect” is especially important for thin-film structures where layer thicknesses are comparable to the absorption depth and the wavelength of the incident light, as is the case for photovoltaic cells fabricated from semiconducting polymers. In order to overcome these problems, one might simply increase the thickness of the active layer to absorb more light. Because of the low mobility of the charge carriers in the polymer:C60 composites, however, the increased internal resistance of thicker films will inevitably lead to a reduced fill factor. An alternative approach is to change the device architecture with the goal of spatially redistributing the light intensity inside the device by introducing an optical spacer between the active layer and the Al electrode as sketched in Figure 1a. [11] Although this revised architecture would appear to solve the problem, the prerequisites for an ideal optical spacer limit the choice of materials: the layer must be a good acceptor and an electron-transport material with a conduction band edge lower in energy than that of the lowest unoccupied molecular orbital (LUMO) of C60; the LUMO must be above (or close to) the Fermi energy of the collecting metal electrode; and it must be transparent to light with wavelengths within the solar spectrum.
1,630 citations
TL;DR: With polyaniline samples prepared using self-stabilized dispersion polymerization, it is found that for samples having room-temperature conductivities in excess of 1,000 S cm-1, the resistivity decreases monotonically as the temperature is lowered down to 5 K, and that the infrared spectra are characteristic of the conventional Drude model even at the lowest frequencies measured.
Abstract: Most plastics are good insulators. But conducting polymers also form the basis of a new field of ‘plastic electronics’. Some of these materials show exceptionally high conductivities, almost as high as metals. But their properties deviate from true metallic behaviour in several important ways. Now a conducting plastic with resistivity properties much more like those of true metals has been synthesized. The properties of this polyaniline compound may bring practical plastic electronics a little closer. True metallic conductivity in a much-studied conducting polymer (polyaniline) is demonstrated, but synthesized by a route that minimizes the density of structural defects believed responsible for the earlier deviations from classical metallic behaviour. Despite nearly three decades of materials development, the transport properties in the ‘metallic state’ of the so-called conducting polymers are still not typical of conventional metals1,2,3,4,5,6,7. The hallmark of metallic resistivity—a monotonic decrease in resistivity with temperature—has not been obtained at temperatures over the full range below room temperature; and a frequency dependent conductivity, σ(ω), typical of metals has also not been observed. In contrast, the low-temperature behaviour of ‘metallic’ polymers has, in all previous cases, exhibited an increase in resistivity as temperature is further decreased, as a result of disorder-induced localization of the charge carriers1,2,3,4. This disorder-induced localization also changes the infrared response such that σ(ω) deviates from the prediction of Drude theory5,6,7. Here we report classic metallic transport data obtained from truly metallic polymers. With polyaniline samples prepared using self-stabilized dispersion polymerization8, we find that for samples having room-temperature conductivities in excess of 1,000 S cm-1, the resistivity decreases monotonically as the temperature is lowered down to 5 K, and that the infrared spectra are characteristic of the conventional Drude model even at the lowest frequencies measured.
804 citations
TL;DR: The functions of hemocytes in innate immune response are reviewed with emphasized on their roles in coagulation, melanization and opsonization.
749 citations
TL;DR: In this review, inflammation is examined as a possible underlying basis for the molecular alterations that link aging and age-related pathological processes and the involvement of another super family of transcription factors, PPARs as regulators of proinflammatory responses and NF-kappaB signaling pathway is described.
Abstract: Emerging pathological evidence indicates that major chronic aging-related diseases such as atherosclerosis, arthritis, dementia, osteoporosis, and cardiovascular diseases, are inflammation-related. In this review, inflammation is examined as a possible underlying basis for the molecular alterations that link aging and age-related pathological processes. A proposal for the molecular inflammation hypothesis of the aging views the redox derangement that occurs during aging as the major factor for increased risk for age-related inflammation. Accumulated data strongly indicate the activation of redox-sensitive transcription factors and dysregulated gene expression under the age-related oxidative stress seems to be the major culprits. Key players involved in the inflammatory process are the age-related upregulation of NF-kappaB, IL-1beta, IL-6, TNFalpha, cyclooxygenase-2, adhesion molecules, and inducible NO synthase. Furthermore, data are presented on the molecular events involved in age-related NF-kappaB activation and phosphorylation by IkappaB kinase/NIK and MAPKs. Experimental data on anti-aging calorie restriction (CR) for its antiinflammatory efficacy by suppressing the upregulated proinflammatory mediators will be reviewed. Also, the involvement of another super family of transcription factors, PPARs (PPARalpha, gamma) as regulators of proinflammatory responses and NF-kappaB signaling pathway is described as well as a discussion on the physiological significance of a well-maintained balance between NF-kappaB and PPARs.
400 citations
TL;DR: In this paper, the thermal conductivity enhancement of water-based MWCNT nanofluid is increased up to 11.3% at a volume fraction of 0.01.
389 citations
TL;DR: HADSC can be an ideal source for therapeutic angiogenesis in ischemic disease and was shown to recover muscle injury and increased vascular density compared with the control group.
Abstract: Background/Aim: It has been reported that adipose tissue contain progenitor cells with angiogenic potential and that therapy based on adipose tissuederived progenitor cells administration may constitute a promising cell therapy in patients with ischemic disease. In this study we evaluated the effect of culture-expanded mesenchymal stem cells (MSC) derived from adipose tissue on neovascularization and blood flow in an animal model of limb ischemia in immunodeficient mice. Methods: MSC were cultured from human adipose tissue by collagenase digestion. Hindlimb ischemia was created by ligating the proximal femoral artery of male nude mice. Human adipose tissue stromal cells (hADSC) were transplanted one day or 7 days after ligation. Results: During culture expansion of hADSC CD34 expression was downregulated. The laser Doppler perfusion index was significantly higher in the CD34(-), Flk-1(-), CD31(-) ADSC-transplanted group than in the control group, even when cells were transplanted 7days after hindlimb ischemia. Histological examination showed that hADSC transplantation recovered muscle injury and increased vascular density, compared with the control group. The effect of hADSC was correlated with the number of transplanted cells, but not with the ratio of CD34 expression. In vitro, hADSC can form vessel-like structure and express von Willibrand Factor. Conditioned media from hADSC increased proliferation and inhibited apoptotic cell death in of human aortic endothelial cells. Conclusion: This study showed that hADSC can be an ideal source for therapeutic angiogenesis in ischemic disease.
333 citations
TL;DR: In this paper, various nanoparticles, such as multi-walled carbon nanotube (MWCNT), fullerene, copper oxide, silicon dioxide and silver, are used to produce nanofluids for enhancing thermal conductivity and lubrication.
330 citations
TL;DR: In this paper, optimized conditions to produce nanofibers using Nylon 6 are investigated and the nylon 6 nanofilters with diameters ranging from several microns down to 100nm or less are designed and evaluated.
305 citations
TL;DR: Applying a surface complexation model for the measurement data of hydrodynamic size, zeta potential, and thermal conductivity, it is shown that surface charge states are mainly responsible for the increase in the present condition and may be the factor incorporating all the mechanisms as well.
Abstract: Although various conjectures have been proposed to explain the abnormal increase in thermal conductivity of nanofluids, the detailed mechanism has not been fully understood and explained. The main reason is due to the lack of knowledge of the most fundamental factor governing the mechanisms such as Brownian motion, liquid layering, phonon transport, surface chemical effects, and agglomeration. Applying a surface complexation model for the measurement data of hydrodynamic size, ζ potential, and thermal conductivity, we have shown that surface charge states are mainly responsible for the increase in the present condition and may be the factor incorporating all the mechanisms as well.
300 citations
TL;DR: This communication reports a nanocatalyst-based electrochemical assay for proteins that has been achieved by signal amplification combined with noise reduction by using a ferrocenyl-tethered dendrimer and hydrophilic immunosensing layer.
Abstract: This communication reports a nanocatalyst-based electrochemical assay for proteins. Ultrasensitive detection has been achieved by signal amplification combined with noise reduction: the signal is amplified both by the catalytic reduction of p-nitrophenol to p-aminophenol by gold-nanocatalyst labels and by the chemical reduction of p-quinone imine to p-aminophenol by NaBH4; the noise is reduced by employing an indium tin oxide electrode modified with a ferrocenyl-tethered dendrimer and a hydrophilic immunosensing layer.
TL;DR: This study suggests two methods for determining the locations of relocated blocks using a branch-and-bound (B&B) algorithm and a decision rule proposed by using an estimator for an expected number of additional relocations for a stack.
TL;DR: Underlying molecular insights into the anti‐inflammatory action of CR in relation to the aging process are provided and it is suggested that the “Inflammation Hypothesis of Aging” supports the molecular basis of the inflammatory process as a plausible cause of the Aging process.
Abstract: Current evidence strongly indicates that reactive oxygen species (ROS) and reactive nitrogen species (RNS) are widely implicated in the inflammatory process. However, mechanistic information is not readily available on the extent to which ROS/RNS contributes to the proinflammatory states of the aging process. The involvement of the underlying inflammation during the aging process and the molecular delineation of anti-inflammatory action of calorie restriction (CR) is described. Age-related upregulations of NF-kappaB, IL-beta, IL-6, TNFalpha, cyclooxygenase-2, and inducible NO synthase are all attenuated by CR. The suppression of the NF-kappaB activation was accomplished by blocking the dissociation of inhibitory IkappaBalpha and IkappaBbeta by CR. These findings provide underlying molecular insights into the anti-inflammatory action of CR in relation to the aging process. Based on these and other available data, it is suggested that the "Inflammation Hypothesis of Aging" supports the molecular basis of the inflammatory process as a plausible cause of the aging process.
TL;DR: In this paper, four soluble perylene diimide derivatives (PDIs) have been prepared and their UV-visible and photoluminescence (PL) spectroscopy, cyclic voltammetry (CV) and thermal properties were studied.
Abstract: Four soluble perylene diimide derivatives (PDIs) have been prepared and their UV–visible and photoluminescence (PL) spectroscopy, cyclic voltammetry (CV) and thermal properties were studied. ITO/PEDOT∶PSS/poly(3-hexylthiophene) (P3HT)∶PDIs/LiF/Al photovoltaic devices were fabricated with PDIs as electron accepting and transporting materials. The highest incident photon-to-current conversion efficiency (IPCE) of 19% at 495 nm and the power conversion efficiency (PCE) of 0.18% under AM 1.5 (100 mW cm−2) with a short-circuit current density (JSC) of 1.32 mA cm−2, an open circuit voltage (VOC) of 0.36 V, and a fill factor (FF) of 0.38 have been achieved with 1 ∶ 4 ratio of P3HT
∶
N,N′-di(1-nonadecyl)perylene-3,4,9,10-bis(dicarboximide) (PDI-C9) after annealing at 80 °C for 1 h. 1,7-Bis(N-pyrrolidinyl)-N,N′-dicyclohexyl-3,4,9,10-perylenebis(dicarboximide) (5-PDI), which has the electron donating pyrrolidinyl group, absorbed the long wavelength region to give IPCE onset higher than 750 nm and the pyrrolidinyl group also raised the LUMO level of 5-PDI to render the high VOC (up to 0.71 V) in photovoltaic device.
TL;DR: Evidence of a nonimmune role for TLR signaling on MSCs is provided and may provide clues to the behavior of transplanted M SCs in vivo.
Abstract: Adult mesenchymal stem cells (MSCs) are promising tools for such applications as tissue engineering and cellular therapy. It is not clear how stem cells exposed to unfavorable conditions (e.g., hypoxia or inflammation) respond to signals of danger after in vivo transplantation. Toll-like receptors (TLRs) play a major role in the immune system, participating in the initial recognition of microbial pathogens and pathogen-associated components. This study was designated to determine the role of TLRs in human MSCs. Reverse transcriptase-polymerase chain reaction (RT-PCR) and flow cytometry analysis demonstrated that MSCs derived from human adipose tissue and bone marrow express TLR-1, TLR-2, TLR-3, TLR-4, TLR-5, TLR-6, and TLR-9. We investigated induction of the differentiation and proliferation of human adipose tissue stromal cells (hADSCs) by TLR agonists, including flagellin, peptidoglycans (PGN), lipopolysaccharide (LPS), the synthetic double-stranded RNA analog poly(I:C), and synthetic CpG oligodeoxydinucleotide (CpG-ODN). None of these agonists, except ODN, affected the proliferation of hADSCs. LPS and PGN increased osteogenic differentiation, but CpG-ODN decreased it. Poly(I:C) itself did not affect adipogenic or osteogenic differentiations, but exerted a synergistic effect on LPS- or PGN-induced osteogenic differentiation. RT-PCR analysis demonstrated that LPS and PGN induce osteogenic markers in hADSCs. TLR agonists affected the expression of chemokines and cytokines differentially. Furthermore, hADSCs affected the expression of specific TLRs in vitro under hypoxic conditions. These data provide evidence of a nonimmune role for TLR signaling on MSCs and may provide clues to the behavior of transplanted MSCs in vivo.
TL;DR: In this paper, the transverse momentum spectra of pi(+/-), p, and (p) over bar p up to 12 GeV/c at midrapidity in centrality selected Au + Au collisions at root s(NN) = 200 GeV are presented.
Abstract: Transverse momentum spectra of pi(+/-), p, and (p) over bar p up to 12 GeV/c at midrapidity in centrality selected Au + Au collisions at root s(NN) = 200 GeV are presented. In central Au + Au collisions, both pi(+/-) and p((p) over bar) show significant suppression with respect to binary scaling at p(T) greater than or similar to 4 GeV/c. Protons and antiprotons are less suppressed than pi(+/-), in the range 1.5 less than or similar to p(T) less than or similar to 6 GeV/c. The pi(-)/pi(+) and (p) over bar /p ratios show at most a weak pT dependence and no significant centrality dependence. The p/pi ratios in central Au + Au collisions approach the values in p + p and d + Au collisions at p(T) greater than or similar to 5 GeV/c. The results at high p(T) indicate that the partonic sources of pi(+/-), p, and (p) over bar have similar energy loss when traversing the nuclear medium
TL;DR: In this article, the authors investigated the electron control and electron transport mechanisms on amorphous indium zinc oxide (IZO) films and confirmed that H2 introduction into the IZO deposition process was effective to increase carrier density.
TL;DR: It was found that direct induction of mitochondrial elongation by blocking mitochondrial fission process with Fis1‐ΔTM or Drp1‐K38A was sufficient to develop senescent phenotypes with increased ROS production, suggesting that mitochondria elongation may play an important role as a mediator in stress‐induced premature senescence.
Abstract: Enlarged or giant mitochondria have often been documented in aged tissues although their role and underlying mechanism remain unclear. We report here how highly elongated giant mitochondria are formed in and related to the senescent arrest. The mitochondrial morphology was progressively changed to a highly elongated form during deferoxamine (DFO)-induced senescent arrest of Chang cells, accompanied by increase of intracellular ROS level and decrease of mtDNA content. Interestingly, under exposure to subcytotoxic doses of H2O2 (200 µM), about 65% of Chang cells harbored elongated mitochondria with senescent phenotypes whereas ethidium bromide (EtBr) (50 ng/ml) only reformed the cristae structure. Elongated giant mitochondria were also observed in TGF β1- or H2O2-induced senescent Mv1Lu cells and in old human diploid fibroblasts (HDFs). In all senescent progresses employed in this study Fis1 protein, a mitochondrial fission modulator, was commonly downexpressed. Overexpression of YFP-Fis1 reversed both mitochondrial elongation and appearance of senescent phenotypes induced by DFO, implying its critical involvement in the arrest. Finally, we found that direct induction of mitochondrial elongation by blocking mitochondrial fission process with Fis1-ΔTM or Drp1-K38A was sufficient to develop senescent phenotypes with increased ROS production. These data suggest that mitochondrial elongation may play an important role as a mediator in stress-induced premature senescence. J. Cell. Physiol. 209: 468–480, 2006. © 2006 Wiley-Liss, Inc.
TL;DR: In this article, the steady shear flow properties of aqueous xanthan gum solutions of different concentrations were measured over a wide range of shear rates using a strain-controlled rheometer, and the viscous behavior was quantitatively discussed using a well-known power law type flow equation with a special emphasis on its importance in industrial processing.
Abstract: Using a strain-controlled rheometer, the steady shear flow properties of aqueous xanthan gum solutions of different concentrations were measured over a wide range of shear rates. In this article, both the shear rate and concentration dependencies of steady shear flow behavior are reported from the experimentally obtained data. The viscous behavior is quantitatively discussed using a well-known power law type flow equation with a special emphasis on its importance in industrial processing and actual usage. In addition, several inelastic-viscoplastic flow models including a yield stress parameter are employed to make a quantitative evaluation of the steady shear flow behavior, and then the applicability of these models is also examined in detail. Finally, the elastic nature is explained with a brief comment on its practical significance. Main results obtained from this study can be summarized as follows: (1) Concentrated xanthan gum solutions exhibit a finite magnitude of yield stress. This may come from the fact that a large number of hydrogen bonds in the helix structure result in a stable configuration that can show a resistance to flow. (2) Concentrated xanthan gum solutions show a marked non-Newtonian shear-thinning behavior which is well described by a power law flow equation and may be interpreted in terms of the conformational status of the polymer molecules under the influence of shear flow. This rheological feature enhances sensory qualities in food, pharmaceutical, and cosmetic products and guarantees a high degree of mixability, pumpability, and pourability during their processing and/or actual use. (3) The Herschel-Bulkley, Mizrahi-Berk, and Heinz-Casson models are all applicable and have equivalent ability to describe the steady shear flow behavior of concentrated xanthan gum solutions, whereas both the Bingham and Casson models do not give a good applicability. (4) Concentrated xanthan gum solutions exhibit a quite important elastic flow behavior which acts as a significant factor for many industrial applications such as food, pharmaceutical, and cosmetic manufacturing processes.
TL;DR: In this article, the transverse momentum spectra for identified charged pions, protons and anti-protons from p + p and d + Au collisions at s NN = 200 GeV were measured around midrapidity ( | y | 0.5 ) over the range of 0.3 p T 10 GeV / c with particle identification from the ionization energy loss and its relativistic rise in the time projection chamber and time-of-flight in STAR.
TL;DR: Those patients with diabetic duration of over 10 years have moreCorneal morphological abnormalities, especially the coefficient of variation in cell size, compared with the normal subjects, and the central corneal thickness was significantly correlated with diabetes duration after controlling for age.
Abstract: This study evaluated the differences of corneal thickness and corneal endothelial morphology in diabetes compared with age-matched, healthy control subjects; in addition, we tested for correlation according to the duration of diabetes. Ultrasound pachymetry and noncontact specular microscopy were performed on 200 patients with diabetes and 100 control subjects. We compared the values for diabetics and normal persons with ANACOVA to adjust for age. Moreover, we examined the correlation between the subject parameters and the duration of diabetes by using a partial correlation coefficient that controlled for age. The diabetic subjects had thicker corneas, less cell density and hexagonality, and more irregular cell size of the corneal endothelium than did the controls (P 0.05). Central corneal thickness was correlated with duration of diabetes (P<0.05), but corneal endothelial morphology was not (P<0.05). Those patients with diabetic duration of over 10 years have more corneal morphological abnormalities, especially the coefficient of variation in cell size, compared with the normal subjects. The central corneal thickness was significantly correlated with diabetic duration after controlling for age.
Journal Article•
TL;DR: Results indicate that W. cibaria isolates possess the ability to inhibit VSC production under both in vitro and in vivo conditions, demonstrating that they bear the potential for development into novel probiotics for use in the oral cavity.
Abstract: Aims: The objective of this study was to characterize the inhibitory effects of Weissella cibaria isolates on volatile sulphur compounds (VSC) production both in vitro and in vivo.
Material and Methods: We isolated and identified three hydrogen peroxide-generating lactobacilli from children's saliva, and assessed their inhibitory effects on VSC production and Fusobacterium nucleatum proliferation. Clinical studies were conducted with 46 subjects in order to measure the VSC of their mouth air.
Results: These lactobacilli were identified as W. cibaria. These isolates inhibited the production of VSC by F. nucleatum (p<0.05). The concentration of F. nucleatum was decreased by 5-log cycles as a result of exposure to the W. cibaria strains (p<0.05), whereas the catalase-treated W. cibaria cultures exerted no evident inhibitory effects on F. nucleatum replication. In the clinical studies, gargling with one isolate resulted in a significant reduction in the levels of H2S and CH3SH by approximately 48.2% (p<0.01) and 59.4% (p<0.05), respectively.
Conclusions: These results indicate that W. cibaria isolates possess the ability to inhibit VSC production under both in vitro and in vivo conditions, demonstrating that they bear the potential for development into novel probiotics for use in the oral cavity.
TL;DR: Even though S 1P alone stimulates adhesion molecule expression, HDL overcomes S1P3 receptor-mediated stimulatory actions through SR-BI/PDZK1-mediated signaling pathways involving phosphatidylinositol 3-kinase and NOS.
TL;DR: Curcumin, a natural, biologically active compound isolated from the commonly used spice turmeric, significantly decreases hypoxia-induced HIF-1alpha protein levels in HepG2 hepatocellular carcinoma cells, suggesting that curcumin may play pivotal roles in tumor suppression via the inhibition of Hif-1 alpha-mediated angiogenesis.
Abstract: Hypoxia-inducible factor-1 (HIF-1) has a central role in cellular responses to hypoxia, including the transcriptional activation of a number of genes involved in angiogenesis in tumors. We found that curcumin, a natural, biologically active compound isolated from the commonly used spice turmeric, significantly decreases hypoxia-induced HIF-1alpha protein levels in HepG2 hepatocellular carcinoma cells. Moreover, curcumin suppressed the transcriptional activity of HIF-1 under hypoxia, leading to a decrease in the expression of vascular endothelial growth factor (VEGF), a major HIF-1 target angiogenic factor. Curcumin also blocked hypoxia-stimulated angiogenesis in vitro and down-regulated HIF-1alpha and VEGF expression in vascular endothelial cells. These findings suggest that curcumin may play pivotal roles in tumor suppression via the inhibition of HIF-1alpha-mediated angiogenesis.
TL;DR: The results indicate that Gracilaria has the potential to remove excess nutrient from coastal areas, and the large-scale cultivation of G. lemaneiformis could be effective to control eutrophication in Chinese coastal waters.
TL;DR: Chlamydomonas reinhardtii biomass was concentrated and then converted into hydrogen and organic acids by anaerobic fermentation with Clostridium butyricum, and the two-step conversion process produced 8.30 mol H 2 from 1 mol starch–glucose equivalent algal biomass via organic acids.
TL;DR: SPC induces differentiation of human adipose-tissue-derived mesenchymal stem cells to smooth-muscle-like cell types through Gi/o-ERK-dependent autocrine secretion of TGF-β, which activates a Smad2-SRF/myocardin-dependent pathway.
Abstract: Mesenchymal stem cells (MSCs) can differentiate into diverse cell types including adipogenic, osteogenic, chondrogenic and myogenic lineages. In the present study, we demonstrated for the first time that sphingosylphosphorylcholine (SPC) induces differentiation of human adipose-tissue-derived mesenchymal stem cells (hATSCs) to smooth-muscle-like cell types. SPC increased the expression levels of several smooth-muscle-specific genes, such as those for alpha-smooth-muscle actin (alpha-SMA), h1-calponin and SM22alpha, as effectively as transforming growth factor beta (TGF-beta1) and TGF-beta3. SPC elicited delayed phosphorylation of Smad2 after 24 hours exposure, in contrast to rapid phosphorylation of Smad2 induced by TGF-beta treatment for 10 minutes. Pretreatment of the cells with pertussis toxin or U0126, an MEK inhibitor, markedly attenuated the SPC-induced expression of beta-SMA and delayed phosphorylation of Smad2, suggesting that the Gi/o-ERK pathway is involved in the increased expression of alpha-SMA through induction of delayed Smad2 activation. In addition, SPC increased secretion of TGF-beta1 through an ERK-dependent pathway, and the SPC-induced expression of alpha-SMA and delayed phosphorylation of Smad2 were blocked by SB-431542, a TGF-beta type I receptor kinase inhibitor, or anti-TGF-beta1 neutralizing antibody. Silencing of Smad2 expression with small interfering RNA (siRNA) abrogated the SPC-induced expression of alpha-SMA. These results suggest that SPC-stimulated secretion of TGF-beta1 plays a crucial role in SPC-induced smooth muscle cell (SMC) differentiation through a Smad2-dependent pathway. Both SPC and TGF-beta increased the expression levels of serum-response factor (SRF) and myocardin, transcription factors involved in smooth muscle differentiation. siRNA-mediated depletion of SRF or myocardin abolished the alpha-SMA expression induced by SPC or TGF-beta. These results suggest that SPC induces differentiation of hATSCs to smooth-muscle-like cell types through G(i/o)-ERK-dependent autocrine secretion of TGF-beta, which activates a Smad2-SRF/myocardin-dependent pathway.