5,377 research outputs found
Salvia miltiorrhiza treatment during early reperfusion reduced postischemic myocardial injury in the rat
Oxidative stress may play a causative role in myocardial ischemia-reperfusion injury. However, it is a relatively understudied aspect regarding an optimal timing of antioxidant intervention during ischemia-reperfusion. The present study investigates the effect of different treatment regimens of Salvia miltiorrhiza (SM) herb extracts containing phenolic compounds that possess potent antioxidant properties on postischemic myocardial functional recovery in the setting of global myocardial ischemia and reperfusion. Langendorff-perfused rat hearts were subjected to 40 min of global ischemia at 37°C followed by 60 min of reperfusion, and were randomly assigned into the untreated control and 2 SM-treated groups (n = 7 per group). In treatment 1 (SM1), 3 mg/mL of water soluble extract of SM was given for 10 min before ischemia and continued during ischemia through the aorta at a reduced flow rate of 60 μL/min, but not during reperfusion. In treatment 2 (SM2), SM (3 mg/mL) was given during the first 15 min of reperfusion. During ischemia, hearts in the control and SM2 groups were given physiological saline at 60 μL/min. The SM1 treatment reduced the production of 15-F2t- isoprostane, a specific index of oxidative stress-induced lipid peroxidation, during ischemia (94 ± 20, 43 ± 6, and 95 ± 15 pg/mL in the coronary effluent in control, SM1, and SM2 groups, respectively; p < 0.05, SM1 vs. control or SM2) and post-poned the onset of ischemic contracture. However, SM2, but not the SM1 regimen, significantly reduced 15-F 2t-isoprostane production during early reperfusion and led to optimal postischemic myocardial functional recovery (left ventricular developed pressure 51 ± 4, 46 ± 4, and 60 ± 6 mmHg in the control, SM1, and SM2 groups, respectively, at 60 min of reperfusion; p < 0.05, SM2 vs. control or SM1) and reduced myocardial infarct size as measured by triphenyltetrazolium chloride staining (26% ± 2%, 22% ± 2%, and 20% ± 2% of the total area in the control, SM1, and SM2 groups, respectively, p < 0.05, SM2 vs. control). It is concluded that S. miltiorrhiza could be beneficial in the treatment of myocardial ischemic injury and the timing of administration seems important. © 2007 NRC.published_or_final_versio
Can energy-price regulations smooth price fluctuations? Evidence from China's coal sector
© 2018 Elsevier Ltd Due to the dominance of coal in China's energy mix, coal prices have always been a challenging part of pricing reform. The recent frequent government interventions raise the key research questions: what is the actual impact of price policies on coal price fluctuations, and how can forward-looking pricing policies be made. By proposing a novel classification of coal pricing policies and introducing an expectation and forward-looking coefficient, the paper examines the relationship between coal price fluctuations and pricing policies using the generalized method of moments (GMM) method. It shows that the lagging coal price and coal demand play a positive role in regulating coal prices, while coal supply and marketization have significantly negative effects on coal price fluctuations. The heterogeneous impacts of price policies are due to differences in market players’ expectations, policy instruments and the methods of policy release. In addition, China's coal pricing policy portfolio from 2013 to 2016 exerted synergy effects on the restraint of coal price fluctuations. As the forward-looking coefficient was considerably low, the government's intervention behaviors were obviously biased towards ex post facto responses. The paper suggests short run and long run policies to advance marketization of coal prices amid the energy transition
Palladium(II)-Schiff base complex immobilized covalently on h-BN: An efficient and recyclable catalyst for aqueous organic transformations
A moisture- and air-stable palladium(II)-Schiff base complex supported on h-BN was simply prepared by using commercially available reagents. This nanomaterial was applied as an excellent and recyclable heterogeneous catalyst for the Suzuki and Heck cross-coupling reactions. And it has been characterized by FT-IR, XRD, SEM, XPS, TG and ICP-AES techniques. High yields, ligand-free, low reaction time, water as solvent, non-toxicity and recyclability of the catalyst are the main merits of these protocols. In addition, a series of pharmacologically relevant products were successfully synthesized using this catalyst. Above all, this work opens up an interesting and attractive avenue for the use of h-BN as an efficient support for heterogeneous catalysts
Oscillatory instability in a driven granular gas
We discovered an oscillatory instability in a system of inelastically
colliding hard spheres, driven by two opposite "thermal" walls at zero gravity.
The instability, predicted by a linear stability analysis of the equations of
granular hydrodynamics, occurs when the inelasticity of particle collisions
exceeds a critical value. Molecular dynamic simulations support the theory and
show a stripe-shaped cluster moving back and forth in the middle of the box
away from the driving walls. The oscillations are irregular but have a single
dominating frequency that is close to the frequency at the instability onset,
predicted from hydrodynamics.Comment: 7 pages, 4 figures, to appear in Europhysics Letter
The phylogeny of Galerucinae (Coleoptera: Chrysomelidae) and the performance of mitochondrial genomes in phylogenetic inference compared to nuclear rRNA genes
With efficient sequencing techniques, full mitochondrial genomes are rapidly replacing other widely used markers, such as the nuclear rRNA genes, for phylogenetic analysis but their power to resolve deep levels of the tree remains controversial. We studied phylogenetic relationships of leaf beetles (Chrysomelidae) in the tribes Galerucini and Alticini (root worms and flea beetles) based on full mitochondrial genomes (103 newly sequenced), and compared their performance to the widely sequenced nuclear rRNA genes (full 18S, partial 28S). Our results show that: (i) the mitogenome is phylogenetically informative from subtribe to family level, and the per-nucleotide contribution to nodal support is higher than that of rRNA genes, (ii) the Galerucini and Alticini are reciprocally monophyletic sister groups, if the classification is adjusted to accommodate several ‘problematic genera’ that do not fit the dichotomy of lineages based on the presence (Alticini) or absence (Galerucini) of the jumping apparatus, and (iii) the phylogenetic results suggest a new classification system of Galerucini with eight subtribes: Oidina, Galerucina, Hylaspina, Metacyclina, Luperina, Aulacophorina, Diabroticina and Monoleptina
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