Inhibition of protein translocation at the endoplasmic reticulum promotes activation of the unfolded protein response.

Selective small-molecule inhibitors represent powerful tools for the dissection of complex biological processes. ES(I) (eeyarestatin I) is a novel modulator of ER (endoplasmic reticulum) function. In the present study, we show that in addition to acutely inhibiting ERAD (ER-associated degradation), ES(I) causes production of mislocalized polypeptides that are ubiquitinated and degraded. Unexpectedly, our results suggest that these non-translocated polypeptides promote activation of the UPR (unfolded protein response), and indeed we can recapitulate UPR activation with an alternative and quite distinct inhibitor of ER translocation. These results suggest that the accumulation of non-translocated proteins in the cytosol may represent a novel mechanism that contributes to UPR activation.

Prenatal exposure to mixtures of persistent environmental chemicals and fetal growth outcomes in Western Australia.

BACKGROUND: Environmental chemicals have been implicated in the etiology of impaired fetal growth. However, few studies have assessed the effects of chemical mixtures or considered the possibility of non-monotonic exposure-response relationships for chemicals that act through the endocrine system. METHODS: We assessed exposure to polybrominated diphenyl ethers, organochlorine pesticides, metals, and perfluorinated alkyl substances in blood and urine samples collected approximately two weeks prior to delivery in 166 non-smoking pregnant women, and subsequent birth weight, length, and head circumference of neonates who were part of the Australian Maternal Exposures to Toxic Substances (AMETS) study. We used Bayesian structured additive regression models with spike-slab priors to estimate mixture effects, identify important exposures, and model non-linearity in exposure-response relationships. RESULTS: Mixtures of polybrominated diphenyl ethers, organochlorine pesticides, metals, and perfluorinated alkyl substances were not associated with fetal growth outcomes. Estimated change in fetal growth outcomes for an increase in exposure from the 25th to 75th percentile suggested no meaningful associations; the strongest evidence was for a small inverse association between birth weight and cesium exposure measured in whole blood (-124 g, 90% credible interval: -240 to -3 g). We identified several chemicals that may be associated with fetal growth non-linearly; however, 90% credible intervals contained small values consistent with no meaningful association. CONCLUSIONS: Using a Bayesian penalized regression method, we assessed the shapes of exposure-response relationships, controlled for confounding by co-exposure, and estimated the single and combined effects of a large mixture of correlated environmental chemicals on fetal growth. Our findings, based on a small sample of mother-neonate pairs, suggest that mixtures of persistent chemicals are not associated with birth weight, length, and head circumference. The potential for non-monotonic relationships between environmental chemicals and fetal growth outcomes warrants further study.

Eeyarestatin I inhibits Sec61-mediated protein translocation at the endoplasmic reticulum.

Production and trafficking of proteins entering the secretory pathway of eukaryotic cells is coordinated at the endoplasmic reticulum (ER) in a process that begins with protein translocation via the membrane-embedded ER translocon. The same complex is also responsible for the co-translational integration of membrane proteins and orchestrates polypeptide modifications that are often essential for protein function. We now show that the previously identified inhibitor of ER-associated degradation (ERAD) eeyarestatin 1 (ES(I)) is a potent inhibitor of protein translocation. We have characterised this inhibition of ER translocation both in vivo and in vitro, and provide evidence that ES(I) targets a component of the Sec61 complex that forms the membrane pore of the ER translocon. Further analyses show that ES(I) acts by preventing the transfer of the nascent polypeptide from the co-translational targeting machinery to the Sec61 complex. These results identify a novel effect of ES(I), and suggest that the drug can modulate canonical protein transport from the cytosol into the mammalian ER both in vitro and in vivo.

Exposures to lead.

The Pacific Basin Consortium for Environment and Health hosted a workshop on Exposures to Lead. Speakers from Australia and the United States of America addressed current research knowledge on lead exposures and health effects in children, risk assessment and communication issues in dealing with lead exposure sources, different methods for assessing exposure, and the variety of scenarios where lead still remains a pollutant of concern. Mining continues to be a source of lead for many communities, and approaches to reducing exposures in these settings present particular challenges. A Perth Declaration for the Global Reduction of Childhood Lead Exposure was signed by participants of the meeting and is aimed at increasing attention to the need to continue to assess lead in the environment and to develop strategies to reduce lead in the environment and exposure by communities.

Emission factors and composition of PM2.5 from laboratory combustion of five Western Australian vegetation types.

This study investigated the emission of PM10 and PM2.5 (particulates with diameters of less than 10 µm and 2.5 µm, respectively) and the chemical composition of PM2.5 from laboratory combustion of five Australian vegetation types (three grasslands, a woodland and a forest). A mix of plants representative of Banksia (woodland) and Jarrah (forest) and three types of grasses (Spinifex - Triodia basedowii; Kimberley grass - Sehima nervosum and Heteropogon contortus; and an invasive grass (Veldt) - Ehrharta calycina) were burnt in 9 combustion conditions comprised of 3 fuel moisture levels (dry, moist, wet) and 3 air flow rates (no, low and high flow). PM (particulate matter) samples were collected onto filters and measured using gravimetric analysis. PM2.5 was then extracted and analyzed for water-soluble metals and polycyclic aromatic hydrocarbons (PAH) concentrations. The largest proportion of PM10 (98%) from vegetation fires was PM2.5. Banksia yielded the highest PM2.5 emission factor (EF), followed by Jarrah and Spinifex. Veldt grass combustion generated significantly higher emissions of PM2.5 compared with the other two grass types. High moisture contents and flow rates resulted in larger emissions of PM2.5. A strong correlation (R2 = 0.84) was observed between the EF for PM2.5 and combustion efficiency, suggesting higher PM emission with lower combustion efficiencies. Potassium and sodium were the most abundant PM2.5-bound water soluble metals, accounting for more than 97% of the total mass of metals analyzed. PAHs were found in significant concentrations, including the carcinogenic benzo(a)pyrene. Pyrene and fluoranthene were the most abundant PAHs detected, accounting for nearly 40% mass of the total PAHs. Indeno(1,2,3-cd)pyrene and benzo(g,h,i)perylene ratio (IND/IND + BghiP) appeared to be produced in a diagnostic ratio that indicated that the PAHs were derived from vegetation fires rather than other sources of emissions. The EF for PM2.5 and its chemical composition (water-soluble metals and PAHs) were strongly influenced by the type of vegetation burned. The results presented in this study could be useful in predicting the risks of human health effects on firefighters and the public who may be exposed to regular bushfires in Australia.

Biosynthesis of the dystonia-associated AAA+ ATPase torsinA at the endoplasmic reticulum.

TorsinA is a widely expressed AAA(+) (ATPases associated with various cellular activities) ATPase of unknown function. Previous studies have described torsinA as a type II protein with a cleavable signal sequence, a single membrane spanning domain, and its C-terminus located in the ER (endoplasmic reticulum) lumen. However, in the present study we show that torsinA is not in fact an integral membrane protein. Instead we find that the mature protein associates peripherally with the ER membrane, most likely through an interaction with an integral membrane protein. Consistent with this model, we provide evidence that the signal peptidase complex cleaves the signal sequence of torsinA, and we show that the region previously suggested to form a transmembrane domain is translocated into the lumen of the ER. The finding that torsinA is a peripheral, and not an integral membrane protein as previously thought, has important implications for understanding the function of this novel ATPase.

Low-level cadmium exposure and cardiovascular outcomes in elderly Australian women: A cohort study.

BACKGROUND: Cadmium has been associated with increased risk of cardiovascular disease (CVD) in observational studies, however there has been a limited focus on this relationship in women. OBJECTIVES: This study investigated the association of urinary cadmium (UCd) concentrations with CVD outcomes and all-cause mortality in elderly Western Australian (WA) women. METHODS: UCd excretion was measured at baseline in 1359 women, mean age 75.2 ±â€¯2.7 years and 14.5 years of atherosclerotic vascular disease (ASVD) hospitalisations and deaths, including both the principle cause of death and all associated causes of death. Health outcome data were retrieved from the Western Australian Data Linkage System. Cox regression analysis was used to estimate hazard ratios of ASVD and all-cause mortality. UCd was ln-transformed and models were adjusted for demographic and CVD risk factors. RESULTS: Median (IQR) concentration of UCd was 0.18 (0.09-0.32) µg/L. In multivariable-adjusted analyses per ln unit (equivalent to ∼2.7 fold) increase in UCd, there was a 36% increase in the risk of death from heart failure and 17% increase in the risk of a heart failure event, respectively (HR = 1.36, 95% CI 1.11-1.67; HR = 1.17, 95% CI 1.01-1.35). When analyses were restricted to never smokers the relationship between UCd and death from heart failure remained (HR 1.29, 95% CI 1.01-1.63). CONCLUSIONS: This study suggests that even at low levels of exposure cadmium may be associated with heart failure hospitalisations and deaths in older women, however given the dilute nature of these urine samples, the results must be interpreted with caution.

In vitro assessment of the toxicity of bushfire emissions: A review.

Bushfires produce many toxic pollutants and the smoke has been shown to have negative effects on human health, especially to the respiratory system. Bushfires are predicted to increase in size and frequency, leading to a greater incidence of smoke and impacts. While there are many epidemiological studies of the potential impact on populations, there are few studies using in vitro methods to investigate the biological effects of bushfire emissions to better understand its toxicity and significance. This review focused on the literature pertaining to in vitro toxicity testing to determine the state of knowledge on current methods and findings on the impacts of bushfire smoke. There was a considerable variation in the experimental conditions, outcomes and test concentrations used by researchers using in vitro methods. Of the studies reviewed, most reported adverse impacts of particulate matter (PM) on cytotoxic and genotoxic responses. Studies on whole smoke were rare. Finer primary particulates from bushfire smoke were generally found to be more toxic than the coarse particulates and the toxicological endpoints of bushfire PM different to ambient PM. However the variation in study designs and experimental conditions made comparisons difficult. This review highlights the need for standard protocols to enable appropriate comparisons between studies to be undertaken including the assessment of physiologically relevant outcomes. Further work is essential to establish the effect of burning different vegetation types and combustion conditions on the toxicity of bushfire emissions to better inform both health and response agencies on the significance of smoke from bushfires.

Relationship between antibiotic resistance genes and metals in residential soil samples from Western Australia.

Increasing drug-resistant infections have drawn research interest towards examining environmental bacteria and the discovery that many factors, including elevated metal conditions, contribute to proliferation of antibiotic resistance (AR). This study examined 90 garden soils from Western Australia to evaluate predictions of antibiotic resistance genes from total metal conditions by comparing the concentrations of 12 metals and 13 genes related to tetracycline, beta-lactam and sulphonamide resistance. Relationships existed between metals and genes, but trends varied. All metals, except Se and Co, were related to at least one AR gene in terms of absolute gene numbers, but only Al, Mn and Pb were associated with a higher percentage of soil bacteria exhibiting resistance, which is a possible indicator of population selection. Correlations improved when multiple factors were considered simultaneously in a multiple linear regression model, suggesting the possibility of additive effects occurring. Soil-metal concentrations must be considered when determining risks of AR in the environment and the proliferation of resistance.

Investigating the relationship between environmental factors and respiratory health outcomes in school children using the forced oscillation technique.

The environmental factors which may affect children's respiratory health are complex, and the influence and significance of factors such as traffic, industry and presence of vegetation is still being determined. We undertook a cross-sectional study of 360 school children aged 5-12 years who lived on the outskirts of a heavy industrial area in Western Australia to investigate the effect of a range of environmental factors on respiratory health using the forced oscillation technique (FOT), a non-invasive method that allows for the assessment of the resistive and reactive properties of the respiratory system. Based on home address, proximity calculations were used to estimate children's exposure to air pollution from traffic and industry and to characterise surrounding green space. Indoor factors were determined using a housing questionnaire. Of the outdoor measures, the length of major roads within a 50m buffer was associated with increased airway resistance (Rrs8). There were no associations between distance to industry and FOT measures. For the indoor environment the presence of wood heating and gas heating in the first year of life was associated with better lung function. The significance of both indoor and outdoor sources of air pollution and effect modifiers such as green space and heating require further investigation.

Children's personal exposure to PM10 and associated metals in urban, rural and mining activity areas.

There has been limited study of children's personal exposure to PM10 and associated metals in rural and iron ore mining activity areas where PM10 concentrations can be very high. We undertook a small study of 70 children where 13 children were recruited in an area of iron ore mining processing and shipping, 15 children from an area in the same region with no mining activities, and 42 children in an urban area. Each child provided a 24h personal exposure PM10 sample, a first morning void urine sample, a hair sample, time activity diary, and self administered questionnaire. Children's 24h personal PM10 concentrations were low (median of 28 µg m(-3) in the mining area; 48 µg m(-3) in the rural area and 45 µg m(-3) in the urban area) with corresponding outdoor PM10 concentrations also low. Some very high personal PM10 concentrations were recorded for individuals (>300 µg m(-3)) with the highest concentrations recorded in the mining and rural areas in the dry season. PM10 concentrations were highly variable. Hair aluminium, cadmium and manganese concentrations were higher in the iron ore activity area, while hair mercury, copper and nickel concentrations were higher in the urban area. Factors such as season and ventilation appear to be important but this study lacked power to confirm this. These results need to be confirmed by a larger study and the potential for absorption of the metals needs to be established along with the factors that increase exposures and the potential for health risks arising from exposure.

Estimating maternal and prenatal exposure to glyphosate in the community setting.

Glyphosate is a herbicide in common use, in both agricultural and residential settings. Controlled residue studies show that glyphosate persists in food crops, allowing for the potential of a large number of people to be exposed. Glyphosate is generally considered safe however there are a number of studies suggesting formulations or additives that may have adverse health effects. To assess the degree of exposure of pregnant women, this study measured glyphosate in composite food samples and estimated exposure based on food frequency questionnaire. 43 pregnant women were recruited and completed a self administered questionnaire with a food frequency component and provided a composite food sample. Twenty food samples were analysed with very low glyphosate concentrations (mean 0.08 mg/kg, range 0.002-0.5 mg/kg) with residues detected in more than 75% of the samples. Maternal dietary exposure was very low (0.001 mg/kg bw/day) and was considerably lower than the predicted National Estimated Daily Intake of glyphosate (0.02 mg/kg bw/day). The estimated exposure based on measured glyphosate in composite food samples corresponded to 0.4% of the acceptable daily intake for glyphosate, and the predicted concentration from dietary information was 4% which is comparable to the National Estimated Daily Intake of 5.5% of the Acceptable Daily Intake of glyphosate. Prenatal exposures were estimated to be significantly lower. While residues of glyphosate are present in food, this study demonstrates that exposure concentrations are low and confirms the current models used to estimate glyphosate exposure.