350 research outputs found
Making sense of institutional change in China: The cultural dimension of economic growth and modernization
No full textBuilding on a new model of institutions proposed by Aoki and the systemic approach to economic civilizations outlined by Kuran, this paper attempts an analysis of the cultural foundations of recent Chinese economic development. I argue that the cultural impact needs to be conceived as a creative process that involves linguistic entities and other public social items in order to provide integrative meaning to economic interactions and identities to different agents involved. I focus on three phenomena that stand at the center of economic culture in China, networks, localism and modernism. I eschew the standard dualism of individualism vs. collectivism in favour of a more detailed view on the self in social relationships. The Chinese pattern of social relations, guanxi, is also a constituent of localism, i.e. a peculiar arrangement and resulting dynamics of central-local interactions in governing the economy. Localism is balanced by culturalist controls of the center, which in contemporary China builds on the worldview of modernism. Thus, economic modernization is a cultural phenomenon on its own sake. I summarize these interactions in a process analysis based on Aoki's framework. --Aoki,culture and the economy,emics/etics,guanxi,relational collectivism,central/local government relations,culturalism,population quality,consumerism
VACCINATION-INDUCED ACTIVATION OF HUMAN BLOOD T CELLS SUPPRESSING PNEUMOCOCCAL POLYSACCHARIDE-SPECIFIC B CELLS
No full textErratum: Author Correction: Misestimation of heritability and prediction accuracy of male-pattern baldness (Nature communications (2018) 9 1 (2537))
No full textThe original version of this Article contained an error in the spelling of the author Julia Sidorenko, which was incorrectly given as Julia Sirodenko. This has now been corrected in both the PDF and HTML versions of the Article. Further, the sixth sentence of the second paragraph of the Correspondence and the legend to Fig.\ua01 incorrectly omitted citation of work by Heilmann-Helmbach, S. et al. This has now been corrected in both the PDF and HTML versions of the Article
Effects of selected natural products on human immunocompetent cells
No full textThe identification of new lead compounds, and the development of novel drugs for the treatment of autoimmune diseases, are of great importance, since today’s available pharmaceuticals often have substantial limitations. Glucocorticoids and drugs that inhibit the deoxyribonucleic acid (DNA) synthesis (e.g. cyclophosphamide) often cause severe side effects, while state-of-the-art biologicals usually impose a heavy financial burden. Plant extracts are a good starting point for the development of immunosuppressive leads, since they are evolutionarily optimized to serve numerous biological functions. The track record of natural product drug discovery for immunosuppressive leads has been distinguished by blockbuster drugs, such as cyclosporin A or tacrolimus; however, a well-planned, multidisciplinary research approach is required for screening plant extracts, characterizing their effects, clarifying targets, and isolating bioactive compounds.
Enhanced T cell proliferation is a feature of autoimmune diseases such as rheumatoid arthritis or multiple sclerosis; therefore, as a starting point, this study investigated the T cell proliferation inhibitory potential of a library of 435 extracts, prepared from plants used in traditional Chinese medicine (TCM). The immunosuppressive activity of the extracts was assessed by a proliferation-based assay utilizing physiologically-relevant anti-CD3 and anti-CD28 stimulated primary human T lymphocytes. It showed that an Artemisia argyi (Asteraceae, A. argyi) ethyl acetate extract and a Boswellia carteri (Burseraceae, B. carteri) dichloromethane (DCM) extract were active, reflected by a half maximal inhibitory concentration (IC50) of 16.2 µg/mL for the A. argyi extract and 27.0 µg/mL for B. carteri extract. The observed inhibitory effect on T cell proliferation was based on a specific intervention of T cell signaling via an interleukin-2 (IL-2)-dependent mechanism, rather than induced apoptosis or necrosis. Further characterizations revealed a reduced expression of the T cell activation markers CD25 and CD69, as well as a decreased production of IL-2 and interferon-γ (IFN-γ), by the A. argyi extract; the B. carteri extract also suppressed the IL-2 and IFN-γ secretion. Moreover, treatment with B. carteri extract resulted in a reduced degranulation capacity of stimulated T cells.
Both extracts were subjected to high-performance liquid chromatography (HPLC)-mass spectrometry (MS)-based activity profiling. A T cell proliferation assay identified 8-acetyl-artanomaloide, arteglasin A, jaceosidin, 1R-canin, and (4S,5S,6S,7S)- and (4R,5R,6S,7S)-seco-tanapartholides as active constituents of A. argyi. The proliferation assay showed that for B. carteri, 3-O-acetyl-8,24-dienetirucallic acid, 3-O-acetyl-7,24-dienetirucallic acid, 3-oxo-8,24-dienetirucallic acid and 3-O-acetyl-α-boswellic acid suppressed the proliferation of stimulated T lymphocytes.
To validate the target of the active A. argyi and B. carteri compounds, monitoring of the T cell signaling cascade was performed, starting with the IL-2 transcription factor activator protein 1 (AP-1), the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and the nuclear factor of activated T cells (NFAT). Suppression of the NF-κB and NFAT activity, with IC50 values between 2.0 and 9.3 µM for NF-κB and 1.6 and 9.3 µM for NFAT, was detected for the A. argyi sesquiterpene lactones. 3-O-acetyl-alpha-boswellic acid was found to be the most promising candidate among the B. carteri compounds, as reflected by an IC50 value of 5.6 µM for NFAT activity suppression. For A. argyi the T cell signaling cascade monitoring was extended to the calcium flux in anti-CD3 stimulated Jurkat T cells. The results indicated a suppression of the calcium flux by 30 µg/mL A. argyi extract; however, no influence on the calcium flux of stimulated Jurkat T cells could be shown for the A. argyi compounds, suggesting that the crude plant extract may affect the signaling on a more upstream level than the single compounds, isolated thus far.
This study also evaluated the potential wound healing and immune modulating capacities of extracts from nine plants that are traditionally used in Nepal to improve wound healing. An ethyl acetate extract of Gmelina arborea (Lamiaceae, G. arborea) positively influenced the wound-healing capacity of human keratinocytes and fibroblasts.
For satisfactory wound healing, a balance between pathogen clearance by inflammatory feedback loops, and regulatory mechanisms to prevent fatal inflammatory responses, is essential; thus, the influence of the extracts on inflammation parameters was addressed. The G. arborea ethyl acetate extract, and an ethyl acetate extract from Bassia longifolia (Sapotaceae, B. longifolia), concentration-dependently inhibited the proliferation of stimulated T cells. This proliferation inhibition was not related to induced apoptosis or necrosis. The observed suppression of T cell proliferation could be linked to a decreased secretion of IL-2, which is essential for the proliferation and differentiation of T lymphocytes. Furthermore, the degranulation capacity of stimulated T cells was shown to decrease in response to treatment with either B. longifolia or G. arborea extract, emphasizing the anti-inflammatory potential of both extracts. Dendritic cells (DCs) play an important role in wound closure, since they increase the cell migration rate of keratinocytes by secreting interleukin-8 (IL-8). A slightly enhanced IL-8 secretion by DCs was detected after treatment with ethyl acetate extracts of either G. arborea or B. longifolia
Investigation of efficacy and safety of plant extracts and natural products on placental and immunocompetent cells
No full textDrug development from natural products, such as herbal extracts and compounds, is a promising research strategy for the identification of new drug candidates. Incessant identification of new lead compounds is imperative to overcome the limitations of many modern treatment options. This holds especially true in immunological diseases, such as chronic inflammation and autoimmune disorders, as current immunosuppressive treatments come with severe side effects and efficacy loss over time. The value of natural products in this endeavour has been impressively demonstrated by compounds like cyclosporin A and tacrolimus.
To address this challenge, a multidisciplinary project was initiated. A library of 600 herbal extracts from Panama was screened for efficacy against the proliferation of lymphocytes, a hallmark feature of autoimmune diseases. An extract of Hyptis brachiata emerged as a highly effective preparation. Subsequent chemical analysis lead to the isolation and characterization of multiple constituents. The main inhibitory potential was later attributed to the antimitotic properties of the isolated aryltetralin lignans, including the well-known podophyllotoxin.
The additional weak cytokine suppression by the extract was evaluated via flow cytometric immunophenotyping. However, no specific compound with corresponding efficacy could be identified.
In the second, main project of this dissertation, the safety of herbal products was evaluated in the context of the treatment of nonpsychotic mental disorders in pregnancy. The herbal preparations included in this project were St. John´s wort (Hypericum perforatum), California poppy (Eschscholzia californica), Valerian (Valeriana officinalis), Lavender (Lavandula angustifolia) and Hops (Humulus lupulus). All of these are commonly used in the treatment of nonpsychotic mental disorders; however, due to their traditional use, they have been only poorly characterised for their safety. In a major effort, a multi-centre, multidisciplinary project aimed at providing the crucially required data on the safety of these preparations was undertaken.
As part of this effort, the toxic and modulatory properties of the extracts and the corresponding constituents were assessed in a variety of assays (cytotoxicity, genotoxicity, and functional) in a placental cell line and primary human immune cells. These two model systems were chosen for their crucial functions in all stages of pregnancy.
None of the extracts exhibited genotoxic, cytotoxic or functional effects, at physiologically relevant concentrations in both models. Only in the artificially high concentration of 100 µg/mL statistically significant cytotoxicity was identified for the extracts from St. Johnʼs wort, California poppy (very weak effect), valerian, and hops in placental cells. At concentrations of ≥ 30µg/mL the extracts of St. John´s wort and Valerian also induced significant inhibition of lymphocyte proliferation.
Additional testing of the corresponding compounds supported these findings. Protopine (California poppy), valerenic acid (valerian), and linalool (lavender) were essentially ineffective in all placental and immunological assays. Meanwhile, hyperforin and hypericin (St. John´s wort), and valtrate (valerian) induced cytotoxicity, in placental cells, in concentrations higher than 1 µM. In the ex vivo lymphocyte model, these three constituents affected viability and proliferation in concentrations ≥ 3 µM. Immunophenotyping of cells treated with these three compounds exhibited varying results on cytokine production and surface marker expression. Overall, the two St. John´s wort compounds showed a more inhibitory phenotype compared to valtrate which induced stimulation on all the cytokines.
Genotoxicity was reported to be of no concern for all tested substances in both model systems
Synthesis of bimetallic nickel nanoparticles as catalysts for the Sabatier reaction
No full textNanoparticles (NP) have become important materials for a variety of chemical technologies. The enhanced surface-area-to-volume ratio of NPs, making them excellent for use as catalyst, in analytical assays, and for antimicrobial applications.
Nickel NPs have exhibited immense potential as important catalyst for the Sabatier reaction, i.e. converting waste to energy via transformation of CO2 into CH4, and could replace the rare earth elements such as Ru, PT, or Rh. In this work we describe the solvothermal synthesis of monometallic and bimetallic nickel nanoparticles.
Monodisperse monometallic Ni NPs were synthesized using Oleylamin as solvent and reducing agent. The nanoparticles were investigated using small angle scattering (SAXS), scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy (EDX), showing that the NPs are stable while the surface is not entirely covered. However, Ni has a high propensity to undergo oxidation, and becoming deactivated by coke formation. Hence, we further explore the preparation of bimetallic NPs, where a second metal is added to stabilize the Ni.
Bimetallic Cu-Ni NPs were synthesized by simultaneous solvothermal reduction. These bimetallic NPs exhibit excellent catalytic properties are promising candidates to be used as catalysts for efficient energy storage
Synthesis of bimetallic nickel nanoparticles as catalysts for the Sabatier reaction
No full textNanoparticles (NPs) have become important materials for a variety of chemical technologies. The enhanced surface-area-to-volume ratio of NPs, making them excellent for use as catalyst, in analytical assays, and for antimicrobial applications.
Nickel NPs have exhibited immense potential as important catalyst for the Sabatier reaction, i.e. converting waste to energy via transformation of CO2 into CH4, and could replace the rare earth elements such as Ru, PT, or Rh. In this work we describe the solvothermal synthesis of monometallic and bimetallic nickel nanoparticles.
Monodisperse monometallic Ni NPs were synthesized using Oleylamin as solvent and reducing agent. The nanoparticles were investigated using small angle scattering (SAXS), scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy (EDX), showing that the NPs are stable while the surface is not entirely covered. However, Ni has a high propensity to undergo oxidation, and becoming deactivated by coke formation. Hence, we further explore the preparation of bimetallic NPs, where a second metal is added to stabilize the Ni.
Bimetallic Cu-Ni NPs were synthesized by simultaneous solvothermal reduction. These bimetallic NPs exhibit excellent catalytic properties are promising candidates to be used as catalysts for efficient energy storage
Synthesis of bimetallic nickel nanoparticles for catalysis
No full textWe present the synthesis of monodisperse monometallic Ni nanoparticles (NPs) and bimetallic NiCu respectively NiCo NPs. The NPs were investigated using SAXS, STEM, EDX, and XANES, showing that the NPs are size tunable and stable while the surface is not entirely covered. Nickel NPs have exhibited immense potential as important catalyst for the Sabatier reaction, i.e. converting waste to energy via transformation of CO2 into CH4
Biodiversity response to forest structure and management: Comparing species richness, conservation relevant species and functional diversity as metrics in forest conservation
No full textAim: We investigated the consistency between richness and trait-based diversity metrics in capturing the effects of management-related habitat factors on biodiversity. The choice of biodiversity metrics can substantially affect the evaluation of conservation tools. However, the relative sensitivity of different metrics is not well investigated, especially in a multi-taxon framework. Location: European beech forests in Denmark. Methods: We studied 20 beech stands comprising four management types (from intensively managed to long unmanaged stands). We analyzed how management-related environmental variables were reflected in the measure of: (i) species richness, (ii) number of conservation-relevant species (red-listed species and old-growth forest indicators) and (iii) functional diversity targeting five organism groups with different habitat requirements, i.e. vascular plants, epiphytic lichens and bryophytes, saproxylic fungi and breeding birds. Results: Plain species richness at stand level was generally misleading, as it did not capture changes in the number of conservation relevant species with changes in management-related environmental variables. The interpretation of functional responses was most informative for the better known vascular plants, while responses were more fragmented for the other organism groups. Overall, however, functional responses were consistent with a loss of specialization and progressive simplification of species assemblages from long-unmanaged to intensively managed stands. Conclusions: Our findings suggest that the occurrence of conservation-relevant species is a sound and relevant metric for planning and evaluating conservation actions, especially for less studied organism groups (e.g., saproxylic fungi and epiphytes). The functional approach is promising, but presupposes the availability of databases of relevant traits
PIPKs are essential for rhizoid elongation and caulonemal cell development in the moss Physcomitrella patens
No full textPtdIns-4,5-bisphosphate is a lipid messenger of eukaryotic cells playing critical roles in processes such as cytoskeleton organization, intracellular vesicular trafficking, secretion, cell motility, regulation of ion channels and nuclear signalling pathways. The enzymes responsible for the synthesis of PtdIns(4,5)P2 are phosphatidylinositol phosphate kinases (PIPKs). The moss Physcomitrella patens contains two PIPKs, PpPIPK1 and PpPIPK2. To study their physiological role, both genes were disrupted by targeted homologous recombination and as a result mutant plants with lower PtdIns(4,5)P2 levels were obtained. A strong phenotype for pipk1, but not for pipk2 single knockout lines, was obtained. The pipk1 knockout lines were impaired in rhizoid and caulonemal cell elongation, whereas pipk1-2 double knockout lines showed dramatic defects in protonemal and gametophore morphology manifested by the absence of rapidly elongating caulonemal cells in the protonemal tissue, leafy gametophores with very short rhizoids, and loss of sporophyte production. pipk1 complemented by overexpression of PpPIPK1 fully restored the wild type phenotype whereas overexpression of the inactive PpPIPK1E885A did not. Overexpression of PpPIPK2 in the pipk1-2 double knockout did not restore the wild type phenotype demonstrating that PpPIPK1 and PpPIPK2 are not functionally redundant. In vivo imaging of the cytoskeleton network revealed that the shortened caulonemal cells in the pipk1 mutants was the result of the absence of the apicobasal gradient of cortical F-actin cables normally observed in wild type caulonemal cells. Our data indicate that both PpPIPKs play a crucial role in the development of the moss P. patens, and particularly in the regulation of tip growth
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