Oxidation of NADH in a Coupled Oxidase-Peroxidase Reaction and its Significance for the Fermentation in Rumen Protozoa of the Genus Isotricha

SYNOPSIS. Cell-free extracts of the anaerobic rumen ciliate Isotricha prostoma possess a strong NADH oxidase activity. Evidence for H₂O₂ as an intermediary product during oxidation of NADH has been obtained. Gatalase activity could not be demonstrated but hydrogen peroxide is removed by a rate limiting NAD peroxidase.
In addition to oxygen several other compounds such as ferricyanide, cytochrome c , menadione and certain dyes may function as electron acceptors during oxidation of NADH. The ferricyanide reductase activity in the Isotricha extracts strongly resembles that of the mitochondrial enzyme from mammalian sources in a number of characteristics.
Partial inhibition of NADH oxidase activity was obtained with the following chelating agents: hydroxylamine, diethyl dithiocarbamate, 2,9-dimethyl-1,10-phenanthroline (DMPH), and 2-thenoyl trifluoroacetone, whereas citrate, tartrate, pyrophosphate, salicylaldoxime, EDTA and 8-hydroxyquinoline had no effect. The peroxidase was blocked completely by 0.42 mM DMPH and this inhibitor was used to block the enzyme in whole cells in experiments on oxygen toxicity. The oxidase was largely insensitive to azide, KCN, and uncouplers. Antimycin A and rotenone caused a partial inhibition of the oxidase when added in very high concentrations. ATP formation occurred during oxidation of NADH, and P/O ratios were 0.1–0.35. Addition of small amounts of oxygen to intact ciliates led to a decrease in the production of hydrogen and butyrate, while the production of acetate was increased and no change in the lactate formation was seen. This shift in fermentation end-products possibly is caused by a competition of oxygen for NADH.     

Hypoxia-increased RAGE expression regulates chemotaxis and pro-inflammatory cytokines release through nuclear translocation of NF-κ B and HIF1α in THP-1 cells

The potential role of hypoxia in mediating the receptor for advanced glycation end products (RAGE) expression deserves to be confirmed. And the role of RAGE in hypoxia-induced chemotaxis and inflammation is still unclear. In present study, THP-1?cells were pretreated with siRNA to block HIF1α, NF-κ B, or RAGE, followed by exposed to hypoxia (combined with H₂O₂ or SNP), and then RAGE expression, nuclear translocation of HIF1α and NF-κ B, release of TNF-α and IL-1β, as well as expression of MCP-1 and CCR2 were measured. The results revealed that RAGE mRNA and protein in THP-1?cells were significantly increased after exposed into hypoxia atmosphere, especially into the solution containing SNP or H₂O₂. Moreover, SNP or H₂O₂ exposure could further amplify hypoxia-induced nuclear translocation of HIF-1α and NF-κ B. Knockdown HIF-1α or NF-κ B by siRNAs could reduce hypoxia- and oxidative stress-induced RAGE hyper-expression. And pretreatment THP-1?cells with RAGE siRNA or NF-κ B siRNA could reduce hypoxia- and oxidative stress-induced expression of MCP-1 and CCR2, and release of TNF-α and IL-1β. Thus, hypoxia not only increases RAGE expression in THP-1?cells by promoting nuclear translocation of NF-κ B and HIF1α, but also regulates chemotaxis and pro-inflammatory cytokines release, which may be partially mediated through upregulation of RAGE expression.     

Measuring Sustainability Efficiency Using a Two‐Stage Data Envelopment Analysis Approach

In this article, we apply an additive two‐stage data envelopment analysis estimator on a panel of 20 countries with advanced economies for the time period 1990–2011 in order to create a composite sustainability efficiency index. We use a window‐based approach in order to study the countries over the years. The sustainability efficiency index is decomposed into production efficiency and eco‐efficiency indicators. The results reveal inequalities among the examined countries between the two stages. The eco‐efficiency stage is characterized by large inequalities among countries and significantly lower efficiency scores than the overall sustainability efficiency and the production efficiency. Finally, it is reported that a country's high production efficiency level does not ensure a high eco‐efficiency performance.     

Fe2+-catalyzed non-enzymatic glycosylation alters collagen conformation during AGE-collagen formation in vitro

Advanced glycation end-products (AGEs) are one of the major factors of hyperglycemia related complications for diabetic patients. We studied the formation of AGEs in type I collagen after Fe²⁺-catalyzed non-enzymatic glycosylation in vitro. Type I collagen isolated from rat tail tendon was incubated with glucose and increasing concentrations of iron ions Fe²⁺. After 4 weeks incubation, cytotoxity of AGEs was indicated by the cytotoxity assay of primary human umbilical vein endothelial cells and primary human monocytes cultured with glycosylated collagen AGEs. Fourier transform infrared spectroscopy analysis revealed that structural changes of functional groups in glycosylated collagen are accelerated by the catalyst Fe²⁺. Using two-dimensional Fourier-transform infrared correlation spectroscopy analyses, for the first time, we demonstrated that the order of structural changes of these functional groups is -CH- > Amide I > Amide II > Amide III > ν(CO) the carboxylic group of Asn, Gln or polyproline amino acid residue in the course of AGE-collagen formation. Knowing the positions of these functional groups in collagen, this order of changes indicates that during glycation of collagen, the structure of the main chain residues in collagen changed first, and then the side chain changed gradually, which may lead to more carboxylic groups exposed to glucose for further formation of AGE-collagen irreversibly. The findings presented may support the design of new therapeutic strategies to prevent or slow down the Fe²⁺-catalyzed glycosylation of collagen and other matrix proteins.     

Peroxidase Isozyme Study in the Interspecific Advanced Lines From Gossypium

By using thin-layer-isoelectrofocusing technique, the authors have been studied peroxidase isozymes activities of the true leaves (at the flower bud stage) and the anthers in the interspecific advanced lines (ALs) from Gossypiurn hirsuturn × G. arboreum, which have been steadily inherited from twenty generations. It was found that: 1. The peroxidase isozymes were similar in different varieties of plants from the same species, but some what different among species originated from the same genome group, and showed remarkably interspecific isozymes difference among species originated from different genome group. 2. The zymograms of the ALs were similar to those of the female parent G. hirsuturn "Keiyi 2”, and obviously different from those of the male parent G. arboreum "Wanzi”.     

Associations of the PTEN − 9C>G polymorphism with insulin sensitivity and central obesity in Chinese

Background

Phosphatase and tensin homolog on chromosome 10 gene (PTEN) is known as a tumor-suppressor gene. Previous studies demonstrated that PTEN dysfunction affects the function of insulin. However, investigations of PTEN single nucleotide polymorphisms (SNPs) and IR-related disease associations are limited. The aim of the present study was to investigate whether its polymorphism could be involved in the risk of metabolic syndrome (MetS).

Methods

The genotype frequency of PTEN − 9C>G polymorphism was determined by using a Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS) method in 530 subjects with MetS and 202 healthy control subjects of the Han Ethnic Chinese population in a case–control analysis.

Results

The PTEN − 9C>G polymorphism was not associated with MetS or its hyperglycemia, hypertension and hypertriglyceridemia components. In the control individuals aged < 60 years or ≥ 60 years, the CG genotype individuals had lower insulin sensitivity than CC individuals (P < 0.05). In the < 60-year-old MetS group and normal glucose tolerance (NGT) subgroup, the CG individuals had lower insulin sensitivity and higher waist circumference (WC) and waist-height-ratio (WHtR) than CC individuals (P < 0.05). Multiple linear regression analysis showed that the PTEN polymorphism (P = 0.001) contributed independently to 4.2% (adjusted R²) of insulin sensitivity variance (estimated by Matsuda ISI), while age (P = 0.004), gender (P = 0.000) and the PTEN polymorphism (P = 0.032) contributed independently to 5.6% (adjusted R²) of WHtR variance.

Conclusions

The CG genotype of PTEN − 9C>G polymorphism was not associated with MetS and some of its components as well. However, it may not only decrease insulin sensitivity in the healthy control and MetS in pre-elderly or NGT subjects, but may also increase the risk of central obesity among these MetS individuals.     

艾塞那肽对糖尿病大鼠肾脏损伤的保护作用

目的：探讨GLP-1类似物艾塞那肽（exenatide）对链脲佐菌素诱导的糖尿病大鼠肾脏的保护作用。方法：SD大鼠随机分为正常组（NC组,n=8）和模型组;模型组给予高脂高糖饲料,喂养4周后腹腔注射STZ（30 mg·kg^-1）建模,72 h后以血糖≥ 16.7 mmol·L^-1为糖尿病成模标准,将成模大鼠随机分为糖尿病对照组（DM组,n=10）、3 μg·kg^-1艾塞那肽干预（Ex-1）组和6μg·kg^-1艾塞那肽干预（Ex-2）组;艾塞那肽组连续皮下注射艾塞那肽（bid）12周,NC组和DM组注射等容积溶剂;测定各组大鼠糖脂代谢变化和肾功能指标如血肌酐（Scr）、尿肌酐（Ucr）、尿素氮（BUN）、24 h尿微量白蛋白排出率（24 h UMA）并计算肌酐清除率（Ccr）;测定肾组织氧化应激指标超氧化物歧化酶（SOD）、丙二醛（MDA）和谷胱甘肽过氧化物酶（GSH-Px）;HE染色观察肾组织病理形态及ELISA法测定肾组织糖基化终末产物AGEs水平。结果：与糖尿病组相比,艾塞那肽可明显改善糖尿病大鼠糖脂代谢,血糖、糖基化血红蛋白（HbAlc）、甘油三脂及胆固醇值均下降（P < 0.05）,肾功能指标明显好转（P < 0.05）且肌酐清除率下降（P < 0.05）,提示肾小球高滤过状态;同时改善糖尿病引起的肾组织病理结构改变,AGEs浓度下降（P < 0.05）,氧化应激指标SOD和GSH-Px活力升高,MDA含量降低（P < 0.05）。结论：艾塞那肽具有肾脏保护作用,其机制可能与抑制糖尿病大鼠肾组织的AGEs生成和改善氧化应激有关。     

Monte Carlo replica‐exchange based ensemble docking of protein conformations

A replica‐exchange Monte Carlo (REMC) ensemble docking approach has been developed that allows efficient exploration of protein–protein docking geometries. In addition to Monte Carlo steps in translation and orientation of binding partners, possible conformational changes upon binding are included based on Monte Carlo selection of protein conformations stored as ordered pregenerated conformational ensembles. The conformational ensembles of each binding partner protein were generated by three different approaches starting from the unbound partner protein structure with a range spanning a root mean square deviation of 1–2.5 Å with respect to the unbound structure. Because MC sampling is performed to select appropriate partner conformations on the fly the approach is not limited by the number of conformations in the ensemble compared to ensemble docking of each conformer pair in ensemble cross docking. Although only a fraction of generated conformers was in closer agreement with the bound structure the REMC ensemble docking approach achieved improved docking results compared to REMC docking with only the unbound partner structures or using docking energy minimization methods. The approach has significant potential for further improvement in combination with more realistic structural ensembles and better docking scoring functions. Proteins 2017; 85:924–937. © 2016 Wiley Periodicals, Inc.     

Enhanced External Counterpulsation Treatment May Intervene The Advanced Atherosclerotic Plaque Progression by Inducing The Variations of Mechanical Factors: A 3D FSI Study Based on in vivo Animal Experiment

Growing evidences suggest that long-term enhanced external counterpulsation (EECP) treatment can inhibit the initiation of atherosclerotic lesion by improving the hemodynamic environment in aortas. However, whether this kind procedure will intervene the progression of advanced atherosclerotic plaque remains elusive and causes great concern in its clinical application presently. In the current paper, a pilot study combining animal experiment and numerical simulation was conducted to investigate the acute mechanical stress variations during EECP intervention, and then to assess the possible chronic effects. An experimentally induced hypercholesterolemic porcine model was developed and the basic hemodynamic measurement was performed in vivo before and during EECP treatment. Meanwhile, A 3D fluid-structure interaction (FSI) model of blood vessel with symmetric local stenosis was developed for the numerical calculation of some important mechanical factors. The results show that EECP augmented 12.21% of the plaque wall stress (PWS), 57.72% of the time average wall shear stress (AWSS) and 43.67% of the non-dimensional wall shear stress gradient (WSSGnd) at throat site of the stenosis. We suggest that long-term EECP treatment may intervene the advanced plaque progression by inducing the significant variations of some important mechanical factors, but its proper effects will need a further research combined follow-up observation in clinic.     

Advances in vertebrate aging research 2007

Among this year's highlights in vertebrate aging research, we find a study in which, contrary to the oxidative stress hypothesis of aging, reduced expression of a major cellular antioxidant, glutathione peroxidase 4, led to a small increase in mouse lifespan. By contrast, a large comparative proteomic analysis discovered a remarkably robust and previous unsuspected inverse association between species lifespan and relative frequency of cysteine residues in mitochondrially encoded respiratory chain proteins only, which the authors attribute to cysteine's ease of oxidation. Another study evaluated more cleanly than any previous work the hypothesis that blood glucose concentration is a key mediator of aging, and concluded that it wasn't. Several new mouse longevity mutants were also reported this year, some ( PAPP-A, IRS-1 , and IRS-2 knockouts) supporting previous work on the importance of insulin/insulin-like growth factor-1 signaling and aging. However, there were inconsistencies between laboratories in some of the results, which merit further investigation. Also, somewhat inconsistent with these findings, over-expression of insulin-like growth factor-1 in heart only lengthened life. From a completely new direction, type 5 adenylyl cyclase knockout mice were observed to live more than 30% longer than controls. Finally, a new program for evaluating potential pharmaceutical interventions in aging and longevity made its appearance, and is notable at this point chiefly for the excellence of its experimental design. A similar program for the disinterested evaluation of reported longevity mutations in mice would be a service to the community of vertebrate aging researchers.