Promotion of iron-induced rat liver microsomal lipid peroxidation by copper

Although copper has been demonstrated to promote lipid peroxidation in a number of systems, the mechanisms involved have not been fully defined. In this study, the role of copper in modifying lipid peroxidation has been explored in rat hepatic microsomes. In an in vitro system containing reduced glutathione (GSH, 200 μM) and Tris buffer, pH 7,4, cupric sulfate (1–50 μM) potentiated lipid peroxidation induced by ferrous sulfate (10 μM) but was unable to elicit peroxidation in the absence of iron. Higher levels of cupric sulfate (100 μM or greater) were inhibitory. The nature as well as the extent of the peroxidative response of microsomes to cupric sulfate were dependent on glutathione levels in addition to those of iron. Cupric sulfate (100 μM) strongly potentiated ferrous ion-induced lipid peroxidation in the presence of 400–800 μM GSH, while it inhibited peroxidation at lower levels of GSH (0–200 μM) and did not affect ferrous ion-induced peroxidation with glutathione levels of 3–10 mM. The potentiating effect of copper on ferrous ion-induced lipid peroxidation was further explored by investigating: (1) potential GSH-mediated reduction of cupric ions; (2) potential copper/GSH-mediated reduction of ferric ions (formed by oxidation during incubation); and (3) possible promotion of propagation reactions by copper/GSH. Our results indicate that cupric ions are reduced by GSH and thus are converted from an inhibitor to an enhancer of iron-induced lipid peroxidation. Cuprous ions appear to potentiate lipid peroxidation by reduction of ferric ions, rather than by promoting propagation reactions. Iron (in a specific Fe⁺²/Fe⁺³ ratio) is then an effective promoter of initiation reactions.     

The Rigorous Development of a System Version Control Program

A rigorous approach to software development is followed in developing a program to control the various components and versions of systems. This particular approach to systematic program development is known as the Vienna Development Method (VDM). This paper documerits the author's early experiences with VDM on a small, yet nontrivial, application. The functional specification of the version control system is presented in detail. Design decisions taken for a prototype implementation are also included. The version control program developed is based upon the Gandalf System Version Control Environment of Carnegie-Mellon University. Both that system and the subject of this case study support the most common forms of component interdependency relations, and methods of system evolution.     

An alternative process for cleaning knives used on meat slaughter floors

Traditionally on slaughter floors operator knives are cleaned by rinsing in hand wash water at 20-40 degrees C followed by brief immersion in baths termed "sterilisers" which contain water no cooler than 82 degrees C. Under Australian legislation, both domestic and export, it is possible for a meat processing establishment to apply to the Controlling Authority for permission to implement an alternative procedure providing that it is at least the equivalent of that legislated. No firm evidence appears to exist for the 82 degrees C requirement and the possibility of replacing this element of the knife cleaning procedure with an alternative procedure using 60 degrees C water and a longer immersion time was investigated at an abattoir slaughtering cattle and sheep. Knives were tested at a range of work stations located along beef and mutton slaughter floors for Aerobic Plate Counts (APCs) and E. coli. For knives used on the beef chain the mean log APC/cm(2) was 2.18 by the current knife cleaning process and 1.78 by the alternate procedure (P<0.001). Using the current system E. coli was isolated from cleaned knives on 20/230 (8.7%) occasions compared with 21/230 (9.1%) occasions using the alternative system. The mean log E. coli of positive knives was 0.43/cm(2) and 0.61/cm(2) from the current and alternative systems, respectively. On the mutton chain the mean log APC/cm(2) was 1.95 using the current knife cleaning process and 1.69 by the alternative procedure (P=0.014). Using the current system E. coli was isolated from cleaned knives on 24/130 (18.5%) occasions compared with 29/130 (22.3%) occasions using the alternative system. The mean log E. coli of positive knives was 0.90/cm(2) and 0.76/cm(2) from the current and alternative systems, respectively. It is concluded that using two knives alternatively, rinsing them in hand wash water, then immersing them between uses in 60 degrees C water provides a microbiological outcome equivalent to rinsing them and momentary dipping in 82 degrees C water.     

A protocol to assess the enzymatic release of dissolved organic phosphorus species in waters under environmentally relevant conditions

A protocol to assess the potential release of dissolved reactive phosphorus (DRP) by enzymatic hydrolysis of dissolved organic phosphorus (DOP) in waters (sediment porewater and sewage liquors in this study) under environmental conditions is presented. This protocol enables the quantification of different classes of DOP compounds using a variety of phosphatase enzymes, i.e., alkaline phosphatase, phosphodiesterase, and phytase. All experiments were carried out within the pH range of most natural waters, i.e., at neutral (pH 7) or slightly alkaline pH (pH 9). Tri-sodium citrate and sodium dodecyl sulfate (SDS) were used in the assays to prevent interferences due to adsorption processes in the presence of multivalent metallic cations and to minimize protein binding. Applying this protocol revealed that labile phosphate monoesters always represented the largest fraction of enzymatically hydrolyzed P in sewage liquors and sediment porewater. Total enzymatically hydrolyzable P (EHP) represented only 16% of the TDP in the sediment porewater but up to 43% in sewage liquors. Because most of the enzymes used in this study are likely to exist in aquatic ecosystems, the EHP fraction might represent a source of potentially bioavailable P of similar magnitude to DRP.     

Escherichia coli biotransformation of daidzein fermentation products from soy‐based foods—relevance to food oestrogenicity‐based functionality

Oestrogenic isoflavones (e.g. daidzein) present in soy‐based foods are likely to be important in food functionality. Biotransformation of daidzein during fermentation‐based soy‐containing food manufacture forms three trihydroxy metabolites, 6‐ortho‐hydroxydaidzein (6‐OHD), 8‐ortho‐hydroxydaidzein (8‐OHD) and 3′‐ortho‐hydroxydaidzein (3′‐OHD) which alters the oestrogenicity of the final food product. We report that Escherichia coli (a key component of the gut microbiome) metabolism converts 8‐OHD to 6‐OHD with a likely concomitant increase in oestrogenicity. This means that the functionality of 8‐OHD‐containing soy‐based foods is altered by gut microbiome metabolism. This change in oestrogenicity‐based food functionality might have benefits for postmenopausal women, while being a feminising health risk for males and could add to the risk of oestrogen‐mediated precocious puberty in girls.     

Sorption and desorption behavior of tributyltin with natural sediments

Tributyltin (TBT) sorption to four natural sediment samples in artificial seawater was examined under a range of modified pH and salinity conditions. Three of the sediment samples were relatively pristine with regard to TBT contamination, but the fourth was a TBT-contaminated sediment from a commercial marina. Sorption of TBT was described well by linear sorption isotherms, with distribution coefficients ranging from 6.1 to 5210 L/kg depending on the pH and salinity. The sediment organic C content and particle size distribution were important determinants of sorption behavior. The presence of resident TBT in the contaminated marina sediment caused a substantial reduction in further TBT sorption. Desorption of TBT from the marina sediment was described by relatively large observed distribution coefficients ranging from 5100 to 9400 L/kg, suggesting that aging effects may reduce sorption reversibility. Increased artificial seawater salinity generally reduced TBT sorption at pH 4 and 6, but enhanced TBT sorption at pH 8. Regardless of salinity, maximum sorption of TBT was observed at pH 6, which is attributed to an optimal balance between the abundance of cationic TBT+ species and deprotonated surface ligands. Consideration of aqueous TBT speciation along with octanol-water partitioning behavior suggests that hydrophobic partitioning of TBTCl(0) to nonpolar organic matter was important for pH < 6, while partitioning of TBTOH(0) was important at higher pH.     

Dietary fibre fractions in hulled and naked winter oat grain: effects of cultivar and various agronomic factors

The dietary fibre fractions in two winter cultivars each of hulled oats and naked oats grown on three sites under different agronomic conditions in two years were studied. Overall, soluble non‐starch polysaccharides (NSP) represented some 540 g kg⁻¹ of total NSP, and this did not vary greatly among cultivars. There was a significant (P < 0.001) positive relationship between total and soluble NSP. Within cultivars there was much greater variability in the concentrations of β‐glucans than in soluble NSP, and overall there was no relationship between the concentrations of the two related fractions. Oat cultivar and factors such as year and site where grown significantly (P < 0.01) affected soluble NSP contents. There were some indications that environmental factors such as temperature, rainfall and sunshine hours may have been responsible for the apparent effects of site and year. On a dehulled basis, traditional hulled cultivars contained significantly (P < 0.05) more β‐glucans than the naked types, and the results suggest that selection of oats for dietary or plant‐breeding purposes should be based on β‐glucan rather than soluble NSP concentrations. © 2000 Society of Chemical Industry     

Organizational unlearning: A risky food safety strategy?

Strategically unlearning specific knowledge, behaviors, and practices facilitates product and process innovation, business model evolution, and new market opportunities and is essential to meet emergent supply chain and customer requirements. Indeed, addressing societal concerns such as climate change and net zero means elements of contemporary practice in food supply chains need to be unlearned to ensure new practices are adopted. However, unlearning is a risky process if crucial knowledge is lost, for example, if knowledge is situated in the supply base not the organization itself, or there is insufficient organizational food safety knowledge generation, curation, and management when new practices/processes are designed and implemented. An exploratory, critical review of management and food safety academic and gray literature is undertaken that aims to consider the cycle of unlearning, learning, and relearning in food organizations and supply chains with particular emphasis on organizational innovation, inertia, and the impact on food safety management systems and food safety performance. Findings demonstrate it is critical with food safety practices, such as duration date coding or refrigeration practices, that organizations “unlearn” in a way that does not increase organizational, food safety, or public health risk. This paper contributes to extant literature by highlighting the organizational vulnerabilities that can arise when strategically unlearning to promote sustainability in a food supply context. Mitigating such organizational, food safety, and public health risk means organizations must simultaneously drive unlearning, learning, and relearning as a dynamic integrated knowledge acquisition and management approach. The research implications are of value to academics, business managers, and wider industry.