Resveratrol reduces infarct size and improves ventricular function after myocardial ischemia in rats

The purpose of this study was to investigate the effect of resveratrol, a polyphenol present in grapes and red wine, on ventricular remodeling after myocardial infarction (MI) in rats. After permanent ligation of the left anterior descending artery, surviving rats were randomly allocated to three groups and treated with 1 mg/kg/day resveratrol (R-1 group), 0.1 mg/kg/day resveratrol (R-0.1 group), or vehicles (control group) administered by intraperitoneal injection once daily for four weeks. We examined the effects of resveratrol by echocardiography, hemodynamic studies, histologic examinations, and real-time quantitative polymerase chain reaction. The R-1 group had significantly increased fractional shortening of the left ventricle, ameliorated left ventricular dilatation, reduced left ventricular end-diastolic pressure, and reduced infarct size. In contrast, the R-0.1 group experienced no beneficial effects on myocardial infarction. The R-1 group also had significantly attenuated expression of myocardial atrial natriuretic peptide and transforming growth factor-beta1 mRNAs. This study indicates that resveratrol is a potent cardioprotective agent in MI rats. Its cardioprotective effects may be due to a reduction of atrial natriuretic peptide and transforming growth factor-beta1, which are known to protect the heart from detrimental remodeling.     

Physiological and chemical indicators for early and late stages of sepsis in conscious rats

Endotoxin shock is a major cause of death in patients with septicemia. Endotoxin induces nitric oxide (NO) production and causes tissue damage. In addition, the release of oxygen free radicals has also been observed in endotoxin shock and was found to be responsible for the occurrence of multiple organ failure. The purpose of the present study was to evaluate suitable indicators for early and late stages of endotoxin shock. The experiments were designed to induce endotoxin shock in conscious rats by means of anEscherichia coli lipopolysaccharide (LPS) injection. Arterial pressure (AP) and heart rate (HR) were continuously monitored for 72 h after LPS administration. The maximal decrease in AP and increase in HR and nitrate/nitrite level occurred at 9–12 h following LPS administration. The white blood cell (WBC) count had decreased at 3 h. Hydroxyl radical (methyl guanidine, MG) decreased rapidly after LPS administration. Plasma levels of blood urea nitrogen (BUN), creatinine (Cr), lactic dehydrogenase (LDH), creatine phosphokinase (CPK), and glutamic oxaloacetic transaminase increased before the rise of amylase. Our results suggest that changes in AP, HR, WBC, free radicals, and chemical substances (BUN, Cr) can possibly serve as approximate indicators for the early stage of endotoxin shock. Severe multiple organ damage may be caused by amylase release in the late stage of endotoxin shock.     

Regulation of ubiquitin and 26S proteasome mediated by phenolic compounds during oxidative stress

Little attention has been devoted to studying the roles of natural antioxidants in the ubiquitin-proteasome pathway during oxidative stress. We demonstrated that a time course revealed that the reassociation of the 19S regulators with the 20S proteasomes occurred automatically and rapidly to reconstitute the 26S proteasomes, with up to 80% completion, within 5 min after H₂O₂ treatment. Ubiquitin, methyl gallate and tannic acid are able to prevent H₂O₂ from inhibiting the 26S activity. We further show that the level of the ubiquitin, S5a and 20S core subunits decreased within 30 min and increased after 24 h of H₂O₂ treatment in Hep-2 cells. Phenolic compounds not only inhibited the 26S activity but also decreased the USP47 levels, which reduce the DNA damage repair rate during oxidative stress; in addition, the presence of DNA fragments, procaspase-3 and a decreased poly (ADP-ribose) polymerase also appeared as a result of the above conditions. Ubiquitin could serve as a protective substrate in H₂O₂ and phenolic compound-treated Hep-2 cells. Methyl gallate and tannic acid, as prooxidants, can attenuate the apoptotic response resulting from long-term oxidative stress. Collectively, these data demonstrate an important role for phenolic compounds in regulating the 26S proteasome and ubiquitin during oxidative stress.     

Effects of Copper,Nickel, and Sulfate from the Smelters at Sudbury,Ontario (Canada) on Microbial Communities in Lakes

Analysis of water and sediments from deep and shallow environments in lakes located 6–154 km east or southeast of the smelters at Sudbury, Ontario (Canada) revealed variable, interactive effects of copper, nickel, and sulfate from smelter fallout on lacustrine microfloras. Metal species in sediments were differentiated by sequential extractions, and the nature, abundances, and activities of microbial populations were represented by chlorophyll-a in water and by CO₂ production, fatty acids, phospholipids, dehydrogenase, alkaline phosphatase, and spectral properties of humic matter in sediments. Smelter fallout declined logarithmically with distance from the smelters, and its effects on microfloras depended on the type of microorganism or microbial process and on environmental factors and the abundances of metal species and detoxifying agents. Extractable copper and nickel had toxic effects, which were not attributable solely to the exchangeable fractions, but in certain cases nickel counteracted copper toxicity. Sedimentary sulfide as a whole or sulfide produced by bacterial sulfate reduction, or low oxidation–reduction potential regardless of sulfide concentration, ameliorated metal toxicity by making the metals less bioavailable; and toxicity showed a “quantum jump” when detoxifying agents fell below certain critical concentrations, implying the existence of threshold levels of bioavailable metals above which toxicity increased abruptly. In some cases metal toxicity was lowest in the lakes closest to the smelters (because sulfate concentrations were highest) as well as in the lakes furthest away, and was highest at intermediate distances. The results also suggest that nickel pollution led to ecological succession whereby nickel-tolerant microbial populations replaced nickel-sensitive ones.     

小兴安岭7种典型林型林分生物量碳密度与固碳能力

森林生物碳储量作为森林生态系统碳库的重要组成部分, 在全球碳循环中发挥着重要作用。以小兴安岭7种典型林型为研究对象, 通过外业样地调查与室内实验分析相结合的方法, 从林分尺度对林分生物量与碳密度进行计量, 分析了林分生物碳储量的空间分配格局, 并对林分年固碳能力与碳汇潜力进行了探讨。结果表明: 小兴安岭不同林型从幼龄林到成熟林的乔木层碳密度增长速率为: 蒙古栎(Quercus mongolica)林>兴安落叶松(Larix gmelinii)林>云冷杉(Picea-Abies)林>樟子松(Pinus sylvestris var. mongolica)林>山杨(Populus davidiana)林>红松(Pinus koraiensis)林>白桦(Betula platyphylla)林。7种典型林型不同龄组(幼龄林、中龄林、近熟林和成熟林)林分生物量碳密度分别为: 红松林31.4、74.7、118.4和130.2 t·hm^-2; 兴安落叶松林28.9、44.3、74.2和113.3 t·hm^-2; 樟子松林22.8、52.0、71.1和92.6 t·hm^-2; 云冷杉林23.1、44.1、77.6和130.3 t·hm^-2; 白桦林18.8、35.3、66.6和88.5 t·hm^-2; 蒙古栎林25.0、20.0、47.5和68.9 t·hm^-2; 山杨林19.8、28.7、43.7和76.6 t·hm^-2。红松林、兴安落叶松林、樟子松林和蒙古栎林在幼龄林时林分年固碳量较高, 其他林型在成熟林时林分年固碳量较高。7种典型林型不同龄组的林分生物量碳密度均随林龄增长而增加, 但不同林型的碳汇功能存在差异, 同一林型不同林龄的生物量碳密度增幅差异也较大。林分年固碳量在0.4-2.8 t·hm^-2之间, 碳汇能力较强、碳汇潜力较大。尤其是小兴安岭目前林分质量较差, 幼龄林和中龄林所占的比重较大, 具有较大的碳汇潜力。研究结果可为森林经营管理及碳汇功能评价提供参考。     

猪链球菌2型的致病机制

猪链球菌2型是重要的人兽共患传染病病原。通常认为该菌的毒力因子与荚膜多糖(CPS)、溶菌酶释放蛋白(MRP)、细胞外因子(EF)和溶血素(SLY)等有关。该文介绍2型猪链球菌的感染途径、侵袭和黏附机制,以及对机体产生细胞因子的影响等。     

Relevance of glycine and cysteine residues as well as N- and C-terminals for the activity of protein histidine phosphatase

There is increasing evidence that reversible phosphorylation of histidine residues regulates numerous important cellular processes. The first protein histidine phosphatase (PHP) from vertebrates was discovered just recently. Here, we report on amino acids and domains essential for activity of PHP. Point mutations of conserved residues and deletions of the N- and C-termini of PHP were analyzed using [³²P-his]ATP-citrate lyase as a substrate. Individual or joint replacement of all cysteine residues by alanine did not affect PHP activity. Deletion of 9 N-terminal amino acids resulted in inactive PHP. Furthermore, only 4 C-terminal residues could be deleted without losing PHP activity. Single or multiple mutations of the glycine-rich domain (Gly⁷⁵, Gly⁷⁷) of a putative nucleotide binding site of PHP (GxGxxG/S) caused inactivation of PHP. Wildtype PHP could be labeled with [α-³²P]ATP. Such radiolabeling was not detectable for catalytically inactive PHP-G75A and PHP-G77A. These data suggest further studies on the interaction between PHP and ATP.     

Natural products as sources of new fungicides (IV): Synthesis and biological evaluation of isobutyrophenone analogs as potential inhibitors of class-II fructose-1,6-bisphosphate aldolase

Several recently identified antifungal compounds share the backbone structure of acetophenones. The aim of the present study was to develop new isobutyrophenone analogs as new antifungal agents. A series of new 2,4-dihydroxy-5-methyl isobutyrophenone derivatives were prepared and characterized by ¹H, ¹³C NMR and MS spectroscopic data. These products were evaluated for in vitro antifungal activities against seven plant fungal pathogens by the mycelial growth inhibitory rate assay. Compounds 3, 4a, 5a, 5b, 5e, 5f and 5g showed a broad-spectrum high antifungal activity. On the other hand, for the first time, these compounds were also assayed as potential inhibitors against Class II fructose-1,6-bisphosphate aldolase (Fba) from the rice blast fungus, Magnaporthe grisea. Compounds 5e and 5g were found to exhibit the inhibition constants (Ki) for 15.12 and 14.27?μM, respectively, as the strongest competitive inhibitors against Fba activity. The possible binding-modes of compounds 5e and 5g were further analyzed by molecular docking algorithms. The results strongly suggested that compound 5g could be a promising lead for the discovery of new fungicides via targeting Class II Fba.