Targeting Unique Ligand Binding Domain Structural Features Downregulates DKK1 in Y537S ESR1 Mutant Breast Cancer Cells.

Resistance to endocrine therapies remains a major clinical hurdle in breast cancer. Mutations to estrogen receptor alpha (ERα) arise after continued therapeutic pressure. Next generation selective estrogen receptor modulators and degraders/downregulators (SERMs and SERDs) show clinical efficacy, but responses are often non-durable. A tyrosine to serine point mutation at position 537 in the ERα ligand binding domain (LBD) is among the most common and most pathogenic alteration in this setting. It enables endocrine therapy resistance by superceding intrinsic structural-energetic gatekeepers of ER hormone-dependence, it enhances metastatic burden by enabling neomorphic ER-dependent transcriptional programs, and it resists SERM and SERD inhibiton by reducing their binding affinities and abilities to antagonize transcriptional coregulator binding. However, a subset of SERMs and SERDs can achieve efficacy by adopting poses that force the mutation to engage in a new interaction that favors the therapeutic receptor antagonist conformation. We previously described a chemically unconventional SERM, T6I-29, that demonstrates significant anti-proliferative activities in Y537S ERα breast cancer cells. Here, we use a comprehensive suite of structural-biochemical, in vitro, and in vivo approaches to better T6I-29's activities in breast cancer cells harboring Y537S ERα. RNA sequencing in cells treated with T6I-29 reveals a neomorphic downregulation of DKK1, a secreted glycoprotein known to play oncogenic roles in other cancers. Importantly, we find that DKK1 is significantly enriched in ER+ breast cancer plasma compared to healthy controls. This study shows how new SERMs and SERDs can identify new therapeutic pathways in endocrine-resistant ER+ breast cancers.

Unconventional isoquinoline-based SERMs elicit fulvestrant-like transcriptional programs in ER+ breast cancer cells.

Estrogen receptor alpha (ERα) is a ligand-dependent master transcriptional regulator and key driver of breast cancer pathology. Small molecule hormones and competitive antagonists favor unique ERα conformational ensembles that elicit ligand-specific transcriptional programs in breast cancer and other hormone-responsive tissues. By affecting disparate ligand binding domain structural features, unconventional ligand scaffolds can redirect ERα genomic binding patterns to engage novel therapeutic transcriptional programs. To improve our understanding of these ERα structure-transcriptional relationships, we develop a series of chemically unconventional antagonists based on the antiestrogens elacestrant and lasofoxifene. High-resolution x-ray co-crystal structures show that these molecules affect both classical and unique structural motifs within the ERα ligand binding pocket. They show moderately reduced antagonistic potencies on ERα genomic activities but are effective anti-proliferative agents in luminal breast cancer cells. Interestingly, they favor a 4-hydroxytamoxifen-like accumulation of ERα in breast cancer cells but lack uterotrophic activities in an endometrial cell line. Importantly, RNA sequencing shows that the lead molecules engage transcriptional pathways similar to the selective estrogen receptor degrader fulvestrant. This advance shows that fulvestrant-like genomic activities can be achieved without affecting ERα accumulation in breast cancer cells.

Tailings dams: Assessing the long-term erosional stability of valley fill designs.

Tailings is a generic term for waste material from the extraction and processing of minerals and frequently contain mineral and chemical residues. They are usually highly erodible and transportable via fluvial processes. Tailings are commonly stored in 'tailings dams' and such dams are a feature of many mine sites. As they impound water and sediment, tailings dams can be at risk from both catastrophic and gradual failure, especially if unmanaged. A fundamental question for their management is, can tailings dams ever be walk-away structures? Catastrophic failure occurs when there is a large scale rapid structural failure of the dam wall suddenly releasing large volumes of water and sediment. However, over time, there will the increased risk of gradual failure by the slow infilling of the dam and the erosion of the dam wall. Failure can occur where water overtops the dam wall and then incises through the wall due to a loss of freeboard in the dam, a situation which is more likely in legacy tailings dams where they have been filled, vegetated and abandoned. Here, firstly, a computer based landscape evolution model (CAESAR-Lisflood) is employed to assess a hypothetical tailings dam failure by erosion. Secondly, using an idealised example, it is demonstrated that given average climate conditions a dam can be sufficiently robust to last centuries. Thirdly, and longer term it is demonstrated that the tailings can be contained if (a) maintenance is conducted to increase the dam wall height over time or (b) a more robust dam wall is constructed to manage extreme events. However, erosion and infill will continue to reduce the integrity of any structure over time. Therefore, it is highly likely that tailings dams will require continued monitoring and maintenance. The method outlined provides a new tool for assessing any tailings facility for its erosional stability.

Modelling soil organic carbon using vegetation indices across large catchments in eastern Australia.

Soil organic carbon (SOC) is an important soil component. However, examining SOC at the large catchment scale is difficult due to the intensive labour requirements. This study examines SOC distribution at large (>500 km2) catchment scales using field-sampled SOC data and remote sensed vegetation indices located in eastern Australia (Krui River catchment - 562 km2; Merriwa River catchment - 808 km2) on grazing land-use basalt soil. The SOC data obtained was compared to digital elevation model (DEM) derived elevation and insolation data, as well as Normalised Difference Vegetation Index (NDVI) and the Enhanced Vegetation Index (EVI) values corresponding to each sample site. These indices were obtained from the MODIS sensor (Terra/Aqua) and Landsat series satellites. Vegetation Indices (VI) captured immediately prior to sampling demonstrated a poor correlation with SOC. The use of multiple, aggregated, prior VI data sets provided a good match with SOC. The strongest match occurred for Landsat 8 EVI, indicating that VIs with higher spatial and spectral resolution, which can account for atmospheric interference, have the potential to produce more accurate SOC mapping (Krui samples in 2006, R2 = 0.31, P < 0.01; Krui sampled in 2014, R2 = 0.41, P < 0.01; Merriwa samples in 2015, R2 = 0.37, P < 0.01). A sensitivity test for both remote sensing platforms demonstrated that the findings were robust. The results demonstrate that VIs are a reliable surrogate for historical vegetation growth in pasture dominated landscapes and therefore soil carbon inputs allowing for mapping of SOC across large catchment scales. Both Landsat and MODIS produced similar results and demonstrate that SOC can be reliably predicted at the large catchment scale and for different catchments in this environment with RMSE range of 0.79 to 1.06. The method and data can be applied globally and provides a new method for environmental assessment.

A method for assessing the long-term integrity of tailings dams.

Mine tailings are a by-product of the processing of minerals. At most mines they are a waste product that needs to be managed. Tailings composition and properties vary widely and are in most cases highly erodible due to their fine particle size and can contain elevated concentrations of unwanted minerals and process chemicals. Therefore, if released to the environment they can be a significant environmental problem. A common management strategy is to store them in 'tailings dams' where they will remain in perpetuity. Little work has been done to assess the long-term erosional behaviour of tailings dams. Computer based Landscape Evolution Models (LEMs) provide information on erosion rates, type of erosion and where erosion is likely to occur. They can therefore provide guidance on long-term behaviour which allows designs to be tested and improved. Here a LEM, SIBERIA, is used to assess two hypothetical tailings dam designs using different surface covers and climates. The results suggest that a tailings dam that can capture rainfall can erode less than a capped design that must shed any runoff. An embankment with a small and steep catchment has minimal erosion potential and any material eroded from the internal wall of the embankment is deposited internally and provides erosion protection. If the external embankment is maintained then there is potential for long-term encapsulation of tailings. The single biggest issue for the employment of LEMs is that of parameterisation and here assumes (1) a uniform and consistent armour or (2) a consistent and self-sustaining vegetation cover. The modelling and methods here provide a template for tailings dam assessment at other sites globally, and will improve tailings dam design and reduce environmental risk.

Effects of grazing exclusion on soil organic carbon: Hillslope and soil profile results (an Australian example).

Soil organic carbon (SOC) is an essential component of the soil-landscape system. It is well recognised that SOC can reduce under some agricultural management practices. In recent years a concerted effort has been undertaken to increase SOC by employing different landscape management practices. Here we compare SOC in a grazing environment to that of an area where cattle have been excluded for over ten years using both a hillslope and whole of soil profile sampling strategy. Surface SOC concentrations (determined by cores) were significantly higher inside the exclusion area when compared to that outside demonstrating a rapid increase in SOC. Whole soil profile (to bedrock) assessment found that SOC decreased with depth both inside and outside of the shelterbelt. While SOC decreased with depth, there were significantly higher surface concentrations inside the exclusion area compared to outside. At depths >20 cm, SOC became increasingly homogenous for both datasets with little difference observed. The results suggest that the influence of the exclusion area on SOC accumulation at the site was only within the top 10-20 cm of the soil profile. The results highlight the importance of soil depth in quantifying SOC within the soil profile and SOC sequestration potential for sites at depth.

Differences in soil organic carbon and soil erosion for native pasture and minimum till agricultural management systems.

There is considerable debate over how different agricultural management systems such as minimum tillage and grazing affect soil organic carbon (SOC), soil nitrogen (SN) concentrations and soil erosion over the long-term. In this study SOC, SN and erosion characteristics were compared over a ten year period for two neighbouring sites with longstanding but different land management strategies; one cropped under a minimum tillage (MT) regime and one used for grazing on largely native pasture. Both sites (Hunter Valley, New South Wales, Australia) shared the same soil type (Euchrozem) and climate. SOC and SN were both found to be ~50% higher at the grazing site while erosion was found to be significantly greater (an order of magnitude) at the cropping site despite the application of MT practices. No discernible link between erosion and either SOC, SN or C:N was evident. While both sites have temporally constant SOC, SN and C:N, the MT site offers scope for increased SOC sequestration.

Soil erosion predictions from a landscape evolution model - An assessment of a post-mining landform using spatial climate change analogues.

Landscape Evolution Modelling (LEM) technologies provide a means by which it is possible to simulate the long-term geomorphic stability of a conceptual rehabilitated landform. However, simulations rarely consider the potential effects of anthropogenic climate change and consequently risk not accounting for the range of rainfall variability that might be expected in both the near and far future. One issue is that high resolution (both spatial and temporal) rainfall projections incorporating the potential effects of greenhouse forcing are required as input. However, projections of rainfall change are still highly uncertain for many regions, particularly at sub annual/seasonal scales. This is the case for northern Australia, where a decrease or an increase in rainfall post 2030 is considered equally likely based on climate model simulations. The aim of this study is therefore to investigate a spatial analogue approach to develop point scale hourly rainfall scenarios to be used as input to the CAESAR - Lisflood LEM to test the sensitivity of the geomorphic stability of a conceptual rehabilitated landform to potential changes in climate. Importantly, the scenarios incorporate the range of projected potential increase/decrease in rainfall for northern Australia and capture the expected envelope of erosion rates and erosion patterns (i.e. where erosion and deposition occurs) over a 100year modelled period. We show that all rainfall scenarios produce sediment output and gullying greater than that of the surrounding natural system, however a 'wetter' future climate produces the highest output. Importantly, incorporating analogue rainfall scenarios into LEM has the capacity to both improve landform design and enhance the modelling software. Further, the method can be easily transferred to other sites (both nationally and internationally) where rainfall variability is significant and climate change impacts are uncertain.

Does introduced fauna influence soil erosion? A field and modelling assessment.

Pigs (Sus scrofa) are recognised as having significant ecological impacts in many areas of the world including northern Australia. The full consequences of the introduction of pigs are difficult to quantify as the impacts may only be detected over the long-term and there is a lack of quantitative information on the impacts of feral pigs globally. In this study the effect of feral pigs is quantified in an undisturbed catchment in the monsoonal tropics of northern Australia. Over a three-year period, field data showed that the areal extent of pig disturbance ranged from 0.3-3.3% of the survey area. The mass of material exhumed through these activities ranged from 4.3 t ha(-1) yr(-1) to 36.0 t ha(-1) yr(-1). The findings demonstrate that large introduced species such as feral pigs are disturbing large areas as well as exhuming considerable volumes of soil. A numerical landscape evolution and soil erosion model was used to assess the effect of this disturbance on catchment scale erosion rates. The modelling demonstrated that simulated pig disturbance in previously undisturbed areas produced lower erosion rates compared to those areas which had not been impacted by pigs. This is attributed to the pig disturbance increasing surface roughness and trapping sediment. This suggests that in this specific environment, disturbance by pigs does not enhance erosion. However, this conclusion is prefaced by two important caveats. First, the long term impact of soil disturbance is still very uncertain. Secondly, modelling results show a clear differentiation between those from an undisturbed environment and those from a post-mining landscape, in which pig disturbance may enhance erosion.

A methodology for the assessment of rehabilitation success of post mining landscapes--sediment and radionuclide transport at the former Nabarlek uranium mine, Northern Territory, Australia.

Protection of the environment post-mining is an important issue, especially where runoff and erosion can lead to undesirable material leaving post-mining landscapes and contaminating surrounding land and watercourses. Methods for assessment of the environmental impact and long-term behaviour of post-mining landforms based on scientific methodology are needed especially where field data are absent or poor. An appraisal of the former Nabarlek uranium mine was conducted to assess the site from a soil erosion perspective as part of an independent evaluation of overall rehabilitation success. Determination of the gross erosion occurring, sediment discharge to Cooper Creek and the resultant sediment associated radionuclide load in Cooper Creek were the primary objectives of the study. These objectives were achieved through the application of several models using parameter values collected from the site. The study found that the area containing the mill tailings repository is extremely stable and meets the guidelines established for long-term storage of uranium mill tailings. Most other areas on the site are stable; however there are some areas with a high sediment loss. Sediment concentration in Cooper Creek, which drains the site, was found to be within the Australian water quality guidelines for fresh water, however sediment concentrations in tributaries were found to exceed recommended levels. Radionuclide determinations on soil samples showed that the highest specific activities (Bq kg-1) were present on a small (0.44 ha) area with a relatively high erosion rate. This small area contributed the majority of the estimated flux to Cooper Creek of uranium-series radionuclides sorbed or structurally incorporated to eroded soil particles sourced from the mine site. This study provides a methodology for assessment of the erosional stability of such a landscape and consequent impact on water quality, using extensive field data and readily available and well known models and methodologies.

Retrospective drug utilization review and the behavior of Medicaid prescribers: an empirical marginal analysis.

The objectives of this study were to evaluate the effectiveness of drug utilization review (DUR) letter intervention on reducing the cost of medications under Medicaid. The target drugs in this study were six antiulcer agents prescribed for Alabama Medicaid recipients. The study group consisted of 100 prescribers who received DUR intervention. A total of 3776 prescribers who did not receive DUR intervention served as the comparison group. Using an interrupted time series design, these 3876 prescribers were studied before and after the implementation of the DUR program. The study found that prescribers' behavior changed after the DUR letter were sent out, resulting in a reduction in the average marginal days of drug therapy and drug reimbursement per recipient. For the target drugs, there was an average savings of $112.73 per prescriber per month and a total of $136,370.82 savings per month for the Alabama Medicaid program.

On the Problem of Two-Dimensional Error Scores: Measures and Analyses of Accuracy, Bias, and Consistency.

Describing and analyzing error for one-dimensional performance tasks is fairly straightforward, but suggestions for describing and analyzing error for two-dimensional performance tasks (e.g., marksmanship) are quite problematic. Specifically, imposing an arbitrary axis onto the two-dimensional work space, along which traditional one-dimensional measures can be computed and analyzed, yields measures of accuracy, bias, and consistency that are entirely dependent upon the choice of axis. The present contribution offers new measures and methods for describing and analyzing data from two-dimensional performances. Unlike the resu1ts from previous suggestions, the approaches described herein yield results that are completely independent of the axes used to quantify the individual two-dimensional trials. These new approaches are strongly related to well-established methods for describing and analyzing error for one-dimensional tasks.

The effect of scale manipulations on validity: targetting frequency rating scales for anticipated performance levels.

A common problem with standard five-point frequency rating scales is their inability to differentiate between objects within a relatively narrow band of the rating dimension. Two alternatives for increasing a scale's ability to reflect existing differences are: increasing the number of positions on the rating scale, or packing the rating scale with quantifiers from a particular portion of the frequency dimension. In this study, three types of rating scale - a standard five-point balanced scale, a longer nine-point balanced scale, and a five-point packed scale - were used to rate two videotaped samples of behaviour, one displaying performance levels from 10% to 100% and the other from 70% to 90%. Each subject's ratings were correlated with true performance levels in each sample of behaviour as a measure of validity. Results showed that for ratings of the wide range of behaviour all three types of scales provided average correlations between the ratings and actual frequencies of the event which exceeded 0.90, with the longer nine-point scale yielding a significantly higher mean correlation than the other two scales. For ratings of the narrow performance range, the nine-point scale provided the highest correlation with the actual frequencies, followed by the packed scale and the standard five-point balanced scale. All differences were significant. Findings suggest that increasing the number of scale positions can significantly increase the validity of ratings obtained. Also, though to a lesser degree, validity of ratings may be enhanced in a shorter scale by using quantifiers from the portion of the frequency continuum where performance are anticipated to lie.

Evidence that phomopsins A and B are not the only toxic metabolites produced by Phomopsis leptostromiformis.

The toxicities of up to four different toxic preparations containing metabolites of Phomopsis leptostromiformis were examined in two experiments with sheep and one with rats. It was shown that the different toxic preparations containing similar amounts of phomopsin A varied substantially in toxicity. Crystalline phomopsin A was the least toxic. It is suggested that the increased toxicity of the other three preparations was due to the presence of toxic metabolites additional to phomopsins A and B. Evidence to support this suggestion is presented.

A comparison of a sheep bioassay and a chemical assay used to estimate the toxicity of lupin stubbles infected with Phomopsis leptostromiformis.

Fifteen lupin stubble samples were tested for toxicity using a sheep bioassay and a chemical assay. A good association, in the functional form of a quadratic equation, existed between the results provided by the two assays. Only 16% of the variance of the chemical assay results was not associated with the sheep bioassay results.