Redox biology of the intestine

Abstract

The intestinal tract, known for its capability for self-renew, represents the first barrier of defence between the organism and its luminal environment. The thiol/disulfide redox systems comprising the glutathione/glutathione disulfide (GSH/GSSG), cysteine/cystine (Cys/CySS) and reduced and oxidized thioredoxin (Trx/TrxSS) redox couples play important roles in preserving tissue redox homeostasis, metabolic functions, and cellular integrity. Control of the thiol-disulfide status at the luminal surface is essential for maintaining mucus fluidity and absorption of nutrients, and protection against chemical-induced oxidant injury. Within intestinal cells, these redox couples preserve an environment that supports physiological processes and orchestrates networks of enzymatic reactions against oxidative stress. In this review, we focus on the intestinal redox and antioxidant systems, their subcellular compartmentation, redox signalling and epithelial turnover, and contribution of luminal microbiota, key aspects that are relevant to understanding redox-dependent processes in gut biology with implications for degenerative digestive disorders, such as inflammation and cancer.     

Implementing Extended Producer Responsibility Legislation

The goal of this article is to contribute to the understanding of how the multiple, and sometimes conflicting, stakeholder perspectives and prevailing conditions (economic, geographic, etc.) in the implementation locality shape extended producer responsibility (EPR) “on the ground.” We provide an in‐depth examination of the implementation dimension of EPR in a specific case study by examining concrete activities at the operational front of the collection and recycling system, and probing the varying stakeholder preferences that have driven a specific system to its status quo. To this end, we conduct a detailed case study of the Washington State EPR implementation for electronic waste. We provide an overview of various stakeholder perspectives and their implications for the attainment of EPR policy objectives in practice. These findings shed light on the intrinsic complexity of EPR implementation. We conclude with recommendations on how to achieve effective and efficient EPR implementation, including improving design incentives, incorporating reuse and refurbishing, expanding product scope, managing downstream material flows, and promoting operational efficiency via fair cost allocation design.     

Biodegradation of Phenol Using Immobilized Nocardia hydrocarbonoxydans in a Pulsed Plate Bioreactor: Effect of Packed Stages,Cell Carrier Loading,and Cell Acclimatization on Startup and Steady-State Behavior

The effect of the number of stages and cell carrier loading on the steady-state and startup performance of a continuous pulsed plate bioreactor with glass beads as the cell carrier material for biodegradation of phenol in wastewater using immobilized Nocardia hydrocarbonoxydans has been studied. It was found that the performance of the pulsed plate bioreactor during startup and at steady state can be improved by an increase in cell carrier loading, number of stages, total plate stack height, and with a decrease in plate spacing. The startup time for the continuous bioreactor can be decreased by increasing the number of preacclimatization steps for the cells. The attainment of steady effluent phenol concentration can be considered as an indication of steady state of the continuous bioreactor, as when phenol concentration attained a steady value, biofilm thickness, and the attached biomass dry weight also attained a constant value.     

Isolated respiring heart mitochondria release reactive oxygen species in states 4 and 3

Isolated mitochondria respiring on physiological substrates, both in state 4 and 3, are reported to be or not to be a source of reactive oxygen species (ROS). The cause of these discrepancies has been investigated. As protein concentration was raised in in vitro assays at 37°C, the rate of H₂O₂ release by rat heart mitochondria supplemented with pyruvate/malate or with succinate (plus rotenone) was shown to increase (0.03–0.15?mg?protein/ml), to decrease (0.2–0.5?mg?protein/ml) and to be negligible (over 0.5?mg?protein/ml). The inhibition of mitochondrial respiration (with rotenone or antimycin A) or the increase in the oxygen concentration dissolved in the assay medium allowed an enhancement of ROS production rate throughout the studied range of protein concentrations. In mitochondria respiring in state 3 on pyruvate/malate or on succinate (plus rotenone), ROS release vanished for protein concentrations over 0.5 or 0.2?mg/ml, respectively. However, ROS production rates measured with low protein concentrations (below 0.1?mg/ml) or in oxygen-enriched media were similar or even slightly higher in the active respiratory state 3 than in the resting state 4 for both substrates. Consequently, these findings indicate that isolated mitochondria, respiring in vitro under conditions of forward electron transport, release ROS with Complex I- and II-linked substrates in the resting condition (state 4) and when energy demand is maximal (state 3), provided that there is sufficient oxygen dissolved in the medium.     

SIGNIFICANT IMPROVEMENT OF QUALITY FOR LONG OLIGONUCLEOTIDES BY USING CONTROLLED PORE GLASS WITH LARGE PORES

A key factor influencing the quality of long oligonucleotides is the choice of controlled pore glass (CPG) which is used as a solid support during oligonucleotide synthesis. We studied the influence of CPG pore size on the quality of 75-mer oligonucleotides. Using electrophoresis and HPLC, we demonstrated failure modes that can occur at certain oligo lengths with 1000A pore size, and compared yield and purity of 75-mer oligos using 1000A and larger pore size CPG. We showed that oligonucleotides with much better quality are obtained using CPG with pore sizes of 1400A and larger. We also identified the key characteristics for CPG selection that lead to the best CPG performance.     

Identification and Quantitation of New Glutamic Acid Derivatives in Soy Sauce by UPLC/MS/MS

Glutamic acid is an abundant amino acid that lends a characteristic umami taste to foods. In fermented foods, glutamic acid can be found as a free amino acid formed by proteolysis or as a non‐proteolytic derivative formed by microorganisms. The aim of the present study was to identify different structures of glutamic acid derivatives in a typical fermented protein‐based food product, soy sauce. An acidic fraction was prepared with anion‐exchange solid‐phase extraction (SPE) and analyzed by UPLC/MS/MS and UPLC/TOF‐MS. α‐Glutamyl, γ‐glutamyl, and pyroglutamyl dipeptides, as well as lactoyl amino acids, were identified in the acidic fraction of soy sauce. They were chemically synthesized for confirmation of their occurrence and quantified in the selected reaction monitoring (SRM) mode. Pyroglutamyl dipeptides accounted for 770 mg/kg of soy sauce, followed by lactoyl amino acids (135 mg/kg) and γ‐glutamyl dipeptides (70 mg/kg). In addition, N‐succinoylglutamic acid was identified for the first time in food as a minor compound in soy sauce (5 mg/kg).     

The Influence of MoOx Anode Stoicheometry on the Performance of Bulk Heterojunction Polymer Solar Cells

Bulk heterojunction solar cells containing molybdenum oxide hole extracting anode contacts have been fabricated with varying stoicheometry using radio frequency reactive sputtering from a Molybdenum metal target. A blend of the newly synthesised conjugated polymer poly[9‐(heptadecan‐9‐yl)‐9H‐carbazole‐2,7‐diyl‐alt‐(5,6‐bis(octyloxy)‐4,7‐di(thiophen‐2‐yl)benzo[c][1,2,5]thiadiazole)‐5,5‐diyl] (PCDTBT‐8) and fullerene [6,6]‐Phenyl‐C71‐butyric acid methyl ester (PC70BM) was used as the photoactive layer and device results show that anodes with greater than 98% Molybdenum (VI) oxide result in peak power conversion efficiencies of 3.7%.The presence of up to 28% of Mo (V) results in no significant reduction in efficiency, however the presence of metallic Mo (IV) and lower oxidation states lead to severe reductions in device performance due to a combination of a large hole extraction energy barrier of approximately 0.9eV and reduced device stability.     

Understanding the Reduced Efficiencies of Organic Solar Cells Employing Fullerene Multiadducts as Acceptors

The use of fullerenes with two or more adducts as acceptors has been recently shown to enhance the performance of bulk‐heterojunction solar cells using poly(3‐hexylthiophene) (P3HT) as the donor. The enhancement is caused by a substantial increase in the open‐circuit voltage due to a rise in the fullerene lowest unoccupied molecular orbital (LUMO) level when going from monoadducts to multiadducts. While the increase in the open‐circuit voltage is obtained with many different polymers, most polymers other than P3HT show a substantially reduced photocurrent when blended with fullerene multiadducts like bis‐PCBM (bis adduct of Phenyl‐C₆₁‐butyric acid methyl ester) or the indene C₆₀ bis‐adduct ICBA. Here we investigate the reasons for this decrease in photocurrent. We find that it can be attributed partly to a loss in charge generation efficiency that may be related to the LUMO‐LUMO and HOMO‐HOMO (highest occupied molecular orbital) offsets at the donor‐acceptor heterojunction, and partly to reduced charge carrier collection efficiencies. We show that the P3HT exhibits efficient collection due to high hole and electron mobilities with mono‐ and multiadduct fullerenes. In contrast the less crystalline polymer Poly[[9‐(1‐octylnonyl)‐9H‐carbazole‐2,7‐diyl]‐2,5‐thiophenediyl‐2,1,3‐benzothiadiazole‐4,7‐diyl‐2,5‐thiophenediyl (PCDTBT) shows inefficient charge carrier collection, assigned to low hole mobility in the polymer and low electron mobility when blended with multiadduct fullerenes.     

财经类院校贫困生心理健康状况及述情障碍

目的：评估财经类院校贫困生心理状况,探讨财经类院校贫困生的心理状况与述情障碍的关系,为更好解决贫困生的心理问题提供依据。方法：对298名贫困学生进行症状自评量表（SymptomChecklist-90,SCL-90）多伦多述情障碍量表（Twenty-ItemTorontoAlexithymiaScale,TAS．20）的测量并与320名非贫困生对照组的结果进行比较。结果：①贫困生组的抑郁、焦虑、人际关系敏感、精神病性、偏执因子分及SCL．90总分因子高于对照组,贫困生组的F1因子明显高于对照组;②述情障碍组SCL-90总分和各因子得分明显高于非述情组;③述情量表总分及各因子分与症状自评量表总分及各因子分显著相关（P〈0．01或P〈0．05）。结论：①与非贫困学生相比,贫困生具有较多的心身症状,主要表现在抑郁、焦虑、人际关系敏感、精神病性、偏执。②述情障碍与心理健康密切相关,述情障碍个体倾向于更容易出现心身症状。③F1（缺乏识别情感的能力）是一个较其它因子更敏感的述情障碍的鉴定指标。     

急性捕食风险不能完全限制饥饿 雌性长爪沙鼠的觅食活动

觅食活动是动物生存和繁殖所必需的基本的活动,受个体生理状态（如饥饿）和环境状况（如捕食、食物可利用性）时空变化的影响,能量状态-风险分配假说指出,动物在应对不同风险时会优化觅食和反捕食努力的时间和能量分配。然而,有关啮齿动物觅食决策的能量状态-捕食风险分配假说的研究结论尚不统一。本研究在野外实验室以艾鼬（Mustela eversmannii）气味作为捕食风险刺激源,以非捕食者（马）气味源作为对照,首先通过Y型观测箱检验雌性饥饿长爪沙鼠（Meriones unguiculatus）对捕食者气味的辨别能力（Wilcoxon 秩检验）;在此基础上通过中立场行为观测箱分别测定饥饿雌鼠在“有食物和天敌气味源”与“有食物和非天敌气味源”环境下的觅食活动,采用Mann-Whitney Z检验比较两者间的行为差异,以验证急性捕食风险限制饥饿沙鼠觅食活动的假设,并探讨动物在饥饿风险与捕食风险共存情况下的觅食行为对策。结果显示,（1）长爪沙鼠对天敌气味反应明显,厌恶和回避有较高潜在捕食风险的空间;（2）虽然觅食潜伏期在捕食风险存在时有所增加,但急性捕食风险并未影响饥饿沙鼠的觅食频次,沙鼠通过缩短每次觅食的持续时间来应对捕食风险;与此同时,（3）饥饿沙鼠在急性捕食风险条件下对环境探究的次数明显增加,一定程度上提高反捕食努力,且自我修饰表现显著,以缓释捕食压力的恐惧效应。这些结果表明,急性捕食风险不能完全抑制饥饿沙鼠的觅食努力,在有捕食风险情况下,饥饿的长爪沙鼠会权衡觅食获取能量和避免捕食的收益和代价,优化觅食策略。本研究结果支持能量状态-风险分配假说关于在短期高风险情况下反捕食努力分配更多,但当动物在饥饿风险持续时间比例显著增加时,动物最终也必须在高风险情况下觅食的预测,也反映了长爪沙鼠对食物资源不可预测及捕食风险高的干旱半干旱荒漠环境的行为适应对策。