Comparison of tissue dosimetry in the mouse following chronic exposure to arsenic compounds

Several chronic bioassays have been conducted in multiple strains of mice in which various concentrations of arsenate or arsenite were administered in the drinking water without a tumorigenic effect. However, one study (Ng et al., 1999) reported a significant increase in tumor incidence in C57Bl/6J mice exposed to arsenic in their drinking water throughout their lifetime, with no tumors reported in controls. A physiologically based pharmacokinetic model for arsenic in the mouse has previously been developed (Gentry et al., 2004) to investigate potential differences in tissue dosimetry of arsenic species across various strains of mice. Initial results indicated no significant differences in blood, liver, or urine dosimetry in B6C3F1 and C57Bl/6 mice for acute or subchronic exposure. The current work was conducted to compare model-predicted estimates of tissue dosimetry to additional kinetic information from the (C57Bl/6 x CBA)F1 and TgAc mouse. The results from the current modeling indicate that the pharmacokinetic parameters derived based on information in the B6C3F1 mouse adequately describe the measured concentrations in the blood/plasma, liver, and urine of both the (C57Bl/6 x CBA)F1 and TgAc mouse, providing further support that the differences in response observed in the chronic bioassays are not related to strain-specific differences in pharmacokinetics. One significant finding was that no increases in skin or lung concentrations of arsenic species in the (C57Bl/6 x CBA)F1 strain were observed following administration of low concentrations (0.2 or 2 mg/L) of arsenate in the drinking water, even though differences in response in the skin were reported. These data suggest that pharmacodynamic changes may be observed following exposure to arsenic compounds without an observable change in tissue dosimetry. These results provided further indirect support for the existence of inducible arsenic efflux in these tissues.

Ionic liquid pretreatment as a means to control the corrosion behavior of magnesium alloys in simulated body fluid

Recently, the use of magnesium alloys as metallic implant materials for biodegradable coronary artery stents has been steadily growing in interest. However, AZ31 magnesium alloys present poor corrosion resistance in the body environment. This work reports on the use of a treatment with low-toxicity IL Trimethyl (butyl) phosphonium diphenyl phosphate P₁₄₄₄DPP, which provides corrosion protection for magnesium alloy AZ31 in simulated body fluid (SBF). Before IL treatment, surface was cleaned by HNO₃ and H₃PO₄ acid pickling solution. The effect of ionic liquid treatment on the corrosion performance of magnesium alloys AZ31in simulated body fluid has been investigated by electrochemical tests and the observation of surface morphology. The results show that this IL treatment succeeded in increasing the corrosion resistance of AZ31 when exposed to SBF.

Trends in the skewness of the body mass index distribution among urban Australian adults, 1980 to 2007

Purpose We analyzed the changes in the body mass index (BMI) distribution for urban Australian adults between 1980 and 2007.

Methods We used data from participants of six consecutive Australian nation-wide surveys with measured weight and height between 1980 and 2007. We used quantile regression to estimate mean BMI (for percentiles of BMI) and prevalence of severe obesity, modeled by natural splines in age, date of birth, and survey date.

Results Since 1980, the right skew in the BMI distribution for Australian adults has increased greatly for men and women, driven by increases in skew associated with age and birth cohort/period. Between 1980 and 2007, the average 5-year increase in BMI was 1 kg/m2 (0.8) for the 95th percentile of BMI in women (men). The increase in the median was about a third of this, and for the 10th percentile, a fifth of this. We estimated that for the cohort born in 1960 around 31% of men and women were obese by age 50 years compared with 11% of the 1930 birth cohort.

Conclusions There have been large increases in the right skew of the BMI distribution for urban Australian adults between 1980 and 2007, and birth cohort effects suggests similar increases are likely to continue.

Chemical and physical speciation of arsenic in a small pond receiving gold mine waste effluent

The chemical and physical speciation of arsenic in a small pond that receives wastewater from a gold mine operation in western Victoria, Australia was studied using differential pulse polarography. By using different sample pretreatments, distinction between the physical states (dissolved or particulate As), between the oxidation states (As(III) or As(V)), and between the degrees of lability (labile or strongly bound) was achieved. The results are interpreted in terms of the physicochemical properties with reference to the use of the pond as a settlement dam for gold mining effluent. The speciation of arsenic was found to vary markedly with the physicochemical properties of the water. A model for the behavior of arsenic in the pond is proposed.

International examples of large-scale systems-theory and practice IV: B2B e-commerce implementation in the Australian context

Two of the most commonly used classifications in IS research are the factor approach and the process approach. While many studies of IS implementation are undertaken using a factor approach, little research so far examines the process of e-commerce implementation, especially in relation to the implementation of e-commerce in business-to-business (B2B) relationships. A holistic understanding of implementation which combines both the factor and process approaches using a case study method, is suggested as particularly suitable because of its ability to capture the reality of e-commerce implementation in an organisation's natural environment and in much greater detail than is possible using one of these approaches alone. In this paper, therefore, we endeavour to contribute to what we perceive as a gap in the body of theory surrounding the implementation process in the business-to-business e-commerce literature. We describe the findings of multiple case studies involving ten major Australian e-commerce initiators. In addition to confirming our earlier finding of the importance of non-technical factors for the success of the implementation process we also present, through our case studies, the various management and business issues associated with the success or failure of B2B e-commerce implementation.

Copper transporters in the human placenta

Copper is an essential micronutrient that is particularly important during pregnancy for normal fetal development. This study determined the mechanisms by which copper is transported from the maternal circulation to the fetal circulation via the placenta and how this transport is regulated by maternal hormone levels.

The role of copper transport proteins in the small intestines

Physiological copper homeostasis involves striking a balance between absorption and secretion. ATP7A was identified at the trans-Golgi network but relocalized to vesicles under copper exposure in the intestine. This suggests that ATP7A may be a rate limiting step in intestinal uptake of copper.

Control of biodegradation of a Mg alloy in simulated body fluid

Mg alloy AZ31 is an attractive candidate for coronary artery stents, as it possesses excellent biocompatibility in human body and good mechanical properties. However, AZ31 magnesium alloys generally have poor corrosion resistance in the body environment. This paper reports on the early stages of an investigation into the corrosion mechanism and the morphology of corrosion of AZ31 in simulated body fluid (SBF). The investigation will also consider ways of improving corrosion resistance of this alloy in SBF through the use of ionic liquids. The results to date have shown that AZ31 suffers severe localized pitting corrosion in SBF. The pits mainly develop adjacent to the Al-Mn intermetallic second phase in the α matrix. Energy Dispersive X-Ray Spectroscopy results revealed the presence of Mg, O, Ca, and P in the layer of corrosion product. Treatment of the AZ31 alloy prior to corrosion testing in SBF with the ionic liquid trimethyl (butyl) phosphonium diphenyl phosphate (P1444DPP) produced some increase in the corrosion resistance of the alloy.

A potential anti-corrosive ionic liquid coating for MG alloy AZ31 in simulated body fluids

Magnesium alloys are attractive materials for biomedical applications, due to their excellent biocompatibility. However, these alloys show fast corrosion rates in the body that limits their clinical applications. Low-toxic ionic liquid (IL) trimethyl(butyl)phosphonium diphenyl phosphate P1444dpp has been investigated to provide corrosion protection for magnesium alloy AZ31 in simulated body fluids (SBFs). This work reports a preliminary exploration of the influence of different treatment temperatures on the corrosion protection properties of IL films for the magnesium alloy AZ31 in SBFs. Results show that the IL treatment at room temperature did not bring significant improvement in the corrosion performance of the AZ31 in SBF. However, when the treatment temperature was increased to 75°C, the IL treatment resulted in a substantial reduction of the corrosion, in particular the reduction of localized pitting corrosion. The influence of ionic liquid treatment on the corrosion performance of the magnesium alloys AZ31 in SBFs has been investigated by electrochemical impedance spectroscopy (EIS) tests and immersion tests.

A longitudinal analysis of the role of biopsychosocial factors in predicting body change strategies among adolescent boys.

In this study we examined the role of biopsychosocial factors on adolescent boys' body modification strategies over an 8-month period. Participants were 434 adolescent boys aged between 11 and 16 years. The majority of respondents were from Anglo-Australian backgrounds (83%); the others were from Asian and European non-English-speaking backgrounds. The results indicated a consistent relationship between perceived encouragement to engage in body change strategies and increases in adolescents' body modification strategies, including muscle gain, weight gain, and weight loss. In addition, poor parent relations, being younger, and higher scores on the pubertal development scale predicted increased use of food supplements. However, the stability of the body modification strategies and the examined variables over the 8-month period were low. Further studies are needed to examine the stability of adolescent self-perceptions over both longer and shorter periods. Moreover, researchers need to include other factors that may be more relevant for adolescent boys (e.g., involvement in sports).

Methodological and conceptual issues in the search for a relationship between animal body-size distributions and benthic habitat architecture

Benthic ecologists have studied the distribution of animal body sizes because it is a form of ‘taxon-free’ classification that may be a useful metric for describing variation within and between ecological communities. In particular, the idea that the allometry of physiological and life-history traits may control species composition and relative abundances implies a functional link between body-size distributions and communities. The physical structure of aquatic habitats has often been cited as the mechanism by which habitat may determine body-size distributions in communities. However, further progress is hindered by a lack of theoretical clarity regarding the mechanisms that connect body size to the characteristics of ecological communities, leading to methods that may obscure interesting trends in body-size data. This review examines the methodological and conceptual issues hindering progress in the search for a relationship between animal body size and habitat architecture and suggests ways to resolve these issues. Problems are identified with current methods for the measurement of animal body size, the data and measures used to quantify body-size distributions and the methods used to identify patterns therein. Fundamentally, renewed emphasis on the mechanisms by which animal body sizes are influenced by habitat architecture is required to refine methodology and synthesise results from pattern-seeking and mechanistic studies.

Fatty acid metabolism in the freshwater fish Murray cod (Maccullochella peelii peelii) deduced by the whole-body fatty acid balance method

The whole-body fatty acid balance method was used to investigate the fatty acid metabolism in Murray cod (Maccullochella peelii peelii) fed diets containing canola (CO) or linseed oil (LO). Murray cod were able to elongate and desaturate both 18 : 2n − 6 and 18 : 3n − 3. In fish fed the CO diet, 54.4% of the 18 : 2n − 6 consumed was accumulated, 38.5% oxidized and 6.4% elongated and desaturated to higher homologs. Fish fed the LO diet accumulated 52.9%, oxidized 37% and elongated and desaturated 8.6% of the consumed 18 : 3n − 3. The overall roles of n − 6 fatty acids appeared more important in Murray cod compared to other freshwater species. Murray cod also showed a preferential order of utilization of C18 fatty acid for energy production (18 : 3n − 3 > 18 : 2n − 6 > 18 : 1n − 9). Moreover, it is demonstrated that an increase in dietary 18 : 3n − 3 is directly responsible of increased desaturase activity and augmented saturated fatty acid accumulation in the fish body. The present study also suggests that, in the context of the possible maximization of the natural ability of fish to produce long chain polyunsaturated fatty acids, the whole-body approach can be considered well suited and informative and Murray cod is a suited candidate to fish oil replacement for its diets.

Energy expenditure and the body cell mass in Cystic Fibrosis

Poor nutritional status in patients with cystic fibrosis (CF) is associated with severe lung disease, and possible causative factors include inadequate intake, malabsorption, and increased energy requirements. Body cell mass (which can be quantified by measurement of total body potassium) provides an ideal standard for measurements of energy expenditure. The aim of this study was to compare resting energy expenditure (REE) in patients with CF with both predicted values and age-matched healthy children and to    determine whether REE was related to either nutritional status or pulmonary function. REE was measured by indirect calorimetry and body cell mass by scanning with total body potassium in 30 patients with CF (12 male, mean AGE = 13.07 ± 0.55 y) and 18 healthy children (six male, mean AGE = 12.56 ± 1.25 y). Nutritional status was expressed as a percentage of predicted total body potassium. Lung function was measured in the CF group by spirometry and expressed as the percentage of predicted forced expiratory volume in 1 s. Mean REE was significantly increased in the patients with CF compared with healthy children (119.3 ± 3.1% predicted versus 103.6 ± 5% predicted, P < 0.001) and, using multiple regression techniques, REE for total body potassium was significantly increased in patients with CF (P = 0.0001). There was no relation between REE and nutritional status or pulmonary disease status in the CF group. In conclusion, REE is increased in children and adolescents with CF but is not directly related to nutritional status or pulmonary disease.