167 research outputs found

    High glucose inhibits human epidermal keratinocyte proliferation for cellular studies on diabetes mellitus

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    In order to more clarify the delayed wound healing in diabetes mellitus, we cultured the human epidermal keratinocytes in both 6 mM (control group) and 12 mM glucose (high-glucose group) of ‘complete’ MCDB 153 medium. Hyperglycaemia slowed the rate of their proliferation and inhibited their DNA synthesis and the production of total proteins. By 1 month after primary seeding in high-glucose group, the cells ceased their proliferation, whereas the cells in control group grew for more than 40 days. Mean population doublings in high-glucose group was 5·27 (vs. 7·25 in control, P = 0·001), and mean population doubling time during 1 month in high glucose group was 5·43 days (vs. 3·65 days in control, P = 0·02). They indicate that prolonged exposure to high glucose decreases the replicative life span of human epidermal keratinocytes in vitro. Furthermore, analysis of fatty acid contents in membrane phospholipids with thin-layer and gas chromatography showed no difference between the cultured keratinocytes in both conditions. Immunocytochemical staining of glucose transporter 1 shows that 28·1% of cells in high-glucose group were almost twice positive of those in control group (13·2%, P = 0·008). The mechanism of the ill effects of high glucose on epidermal keratinocytes is not so far clear, but it indicates the possibility of any direct effect of hyperglycaemia on glucose metabolism without changing lipid metabolism on cell membrane. The high-glucose group presented in this report can be available as an in vitro valuable study model of skin epidermal condition on diabetes mellitus.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72307/1/j.1742-4801.2005.00148.x.pd

    The rogue nature of hiatuses in a global warming climate

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    The nature of rogue events is their unlikelihood and the recent unpredicted decade-long slowdown in surface warming, the so-called hiatus, may be such an event. However, given decadal variability in climate, global surface temperatures were never expected to increase monotonically with increasing radiative forcing. Here surface air temperature from 20 climate models is analyzed to estimate the historical and future likelihood of hiatuses and “surges” (faster than expected warming), showing that the global hiatus of the early 21st century was extremely unlikely. A novel analysis of future climate scenarios suggests that hiatuses will almost vanish and surges will strongly intensify by 2100 under a “business as usual” scenario. For “CO2 stabilisation” scenarios, hiatus, and surge characteristics revert to typical 1940s values. These results suggest to study the hiatus of the early 21st century and future reoccurrences as rogue events, at the limit of the variability of current climate modelling capability

    A review of elliptical and disc galaxy structure, and modern scaling laws

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    A century ago, in 1911 and 1913, Plummer and then Reynolds introduced their models to describe the radial distribution of stars in `nebulae'. This article reviews the progress since then, providing both an historical perspective and a contemporary review of the stellar structure of bulges, discs and elliptical galaxies. The quantification of galaxy nuclei, such as central mass deficits and excess nuclear light, plus the structure of dark matter halos and cD galaxy envelopes, are discussed. Issues pertaining to spiral galaxies including dust, bulge-to-disc ratios, bulgeless galaxies, bars and the identification of pseudobulges are also reviewed. An array of modern scaling relations involving sizes, luminosities, surface brightnesses and stellar concentrations are presented, many of which are shown to be curved. These 'redshift zero' relations not only quantify the behavior and nature of galaxies in the Universe today, but are the modern benchmark for evolutionary studies of galaxies, whether based on observations, N-body-simulations or semi-analytical modelling. For example, it is shown that some of the recently discovered compact elliptical galaxies at 1.5 < z < 2.5 may be the bulges of modern disc galaxies.Comment: Condensed version (due to Contract) of an invited review article to appear in "Planets, Stars and Stellar Systems"(www.springer.com/astronomy/book/978-90-481-8818-5). 500+ references incl. many somewhat forgotten, pioneer papers. Original submission to Springer: 07-June-201

    Possible causes of data model discrepancy in the temperature history of the last Millennium

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    Model simulations and proxy-based reconstructions are the main tools for quantifying pre-instrumental climate variations. For some metrics such as Northern Hemisphere mean temperatures, there is remarkable agreement between models and reconstructions. For other diagnostics, such as the regional response to volcanic eruptions, or hemispheric temperature differences, substantial disagreements between data and models have been reported. Here, we assess the potential sources of these discrepancies by comparing 1000-year hemispheric temperature reconstructions based on real-world paleoclimate proxies with climate-model-based pseudoproxies. These pseudoproxy experiments (PPE) indicate that noise inherent in proxy records and the unequal spatial distribution of proxy data are the key factors in explaining the data-model differences. For example, lower inter-hemispheric correlations in reconstructions can be fully accounted for by these factors in the PPE. Noise and data sampling also partly explain the reduced amplitude of the response to external forcing in reconstructions compared to models. For other metrics, such as inter-hemispheric differences, some, although reduced, discrepancy remains. Our results suggest that improving proxy data quality and spatial coverage is the key factor to increase the quality of future climate reconstructions, while the total number of proxy records and reconstruction methodology play a smaller role

    European summer temperatures since Roman times

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    The spatial context is critical when assessing present-day climate anomalies, attributing them to potential forcings and making statements regarding frequency and severity in the long-term perspective. Recent initiatives have expanded the number of high-quality proxy-records and developed new reconstruction methods. These advances allow more rigorous regional past temperature reconstructions and the possibility of evaluating climate models on policy-relevant, spatio-temporal scales. We provide a new proxy-based, annually-resolved, spatial reconstruction of the European summer temperature fields back to 755 CE based on a Bayesian hierarchical modelling (BHM), together with estimates of the European mean temperature variation since 138 BCE based on Composite-plus-Scaling. Our reconstructions compare well with independent instrumental and proxy-based temperature estimates, but suggest a larger amplitude in summer temperature variability than previously reported. Temperature differences between the medieval period, the recent period and Little Ice Age are larger in reconstructions than simulations. This may indicate either inflated variability of the reconstructions, a lack of sensitivity to external forcing on sub-hemispheric scales in the climate models and/or an underestimation of internal variability on centennial and longer time scales including the representation of internal feedback mechanisms

    Two-year follow-up of 4 months metformin treatment vs. placebo in ST-elevation myocardial infarction:data from the GIPS-III RCT

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    OBJECTIVES: Preclinical and clinical studies suggested cardioprotective effects of metformin treatment. In the GIPS-III trial, 4 months of metformin treatment did not improve left ventricular ejection fraction in patients presenting with ST-elevation myocardial infarction (STEMI). Here, we report the 2-year follow-up results. METHODS: Between January 2011 and May 2013, 379 STEMI patients without diabetes undergoing primary percutaneous coronary intervention were randomized to a 4-month treatment with metformin (500 mg twice daily) (N = 191) or placebo (N = 188) in the University Medical Center Groningen. Two-year follow-up data was collected to determine its effect on predefined secondary endpoints: the incidence of major adverse cardiac events (MACE), its individual components, all-cause mortality, and new-onset diabetes. RESULTS: For all 379 patients all-cause mortality data were available. For seven patients (2%) follow-up data on MACE was limited, ranging from 129 to 577 days. All others completed the 2-year follow-up visit. Incidence of MACE was 11 (5.8%) in metformin and 6 (3.2%) in placebo treated patients [hazard ratio (HR) 1.84, confidence interval (CI) 0.68-4.97, P = 0.22]. Three patients died in the metformin group and one in the placebo treatment group. Individual components of MACE were also comparable between both groups. New-onset diabetes mellitus was 34 (17.8%) in metformin and 32 (17.0%) in placebo treated patients (odds ratio 1.15, CI 0.66-1.98, P = 0.84). After multivariable adjustment the incidence of MACE was comparable between the treatment groups (HR 1.02, CI 0.10-10.78, P = 0.99). CONCLUSIONS: Four months metformin treatment initiated at the time of hospitalization in STEMI patients without diabetes did not exert beneficial long-term effects. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT01217307
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