Chemistry domain of applicability evaluation against existing estrogen receptor high-throughput assay-based activity models

Introduction

The U. S. Environmental Protection Agency's Endocrine Disruptor Screening Program (EDSP) Tier 1 assays are used to screen for potential endocrine system-disrupting chemicals. A model integrating data from 16 high-throughput screening assays to predict estrogen receptor (ER) agonism has been proposed as an alternative to some low-throughput Tier 1 assays. Later work demonstrated that as few as four assays could replicate the ER agonism predictions from the full model with 98% sensitivity and 92% specificity. The current study utilized chemical clustering to illustrate the coverage of the EDSP Universe of Chemicals (UoC) tested in the existing ER pathway models and to investigate the utility of chemical clustering to evaluate the screening approach using an existing 4-assay model as a test case. Although the full original assay battery is no longer available, the demonstrated contribution of chemical clustering is broadly applicable to assay sets, chemical inventories, and models, and the data analysis used can also be applied to future evaluation of minimal assay models for consideration in screening.

Methods

Chemical structures were collected for 6,947 substances via the CompTox Chemicals Dashboard from the over 10,000 UoC and grouped based on structural similarity, generating 826 chemical clusters. Of the 1,812 substances run in the original ER model, 1,730 substances had a single, clearly defined structure. The ER model chemicals with a clearly defined structure that were not present in the EDSP UoC were assigned to chemical clusters using a k-nearest neighbors approach, resulting in 557 EDSP UoC clusters containing at least one ER model chemical.

Results and Discussion

Performance of an existing 4-assay model in comparison with the existing full ER agonist model was analyzed as related to chemical clustering. This was a case study, and a similar analysis can be performed with any subset model in which the same chemicals (or subset of chemicals) are screened. Of the 365 clusters containing >1 ER model chemical, 321 did not have any chemicals predicted to be agonists by the full ER agonist model. The best 4-assay subset ER agonist model disagreed with the full ER agonist model by predicting agonist activity for 122 chemicals from 91 of the 321 clusters. There were 44 clusters with at least two chemicals and at least one agonist based upon the full ER agonist model, which allowed accuracy predictions on a per-cluster basis. The accuracy of the best 4-assay subset ER agonist model ranged from 50% to 100% across these 44 clusters, with 32 clusters having accuracy ≥90%. Overall, the best 4-assay subset ER agonist model resulted in 122 false-positive and only 2 false-negative predictions compared with the full ER agonist model. Most false positives (89) were active in only two of the four assays, whereas all but 11 true positive chemicals were active in at least three assays. False positive chemicals also tended to have lower area under the curve (AUC) values, with 110 out of 122 false positives having an AUC value below 0.214, which is lower than 75% of the positives as predicted by the full ER agonist model. Many false positives demonstrated borderline activity. The median AUC value for the 122 false positives from the best 4-assay subset ER agonist model was 0.138, whereas the threshold for an active prediction is 0.1.

Conclusion

Our results show that the existing 4-assay model performs well across a range of structurally diverse chemicals. Although this is a descriptive analysis of previous results, several concepts can be applied to any screening model used in the future. First, the clustering of the chemicals provides a means of ensuring that future screening evaluations consider the broad chemical space represented by the EDSP UoC. The clusters can also assist in prioritizing future chemicals for screening in specific clusters based on the activity of known chemicals in those clusters. The clustering approach can be useful in providing a framework to evaluate which portions of the EDSP UoC chemical space are reliably covered by in silico and in vitro approaches and where predictions from either method alone or both methods combined are most reliable. The lessons learned from this case study can be easily applied to future evaluations of model applicability and screening to evaluate future datasets.

Optimizing androgen receptor prioritization using high-throughput assay-based activity models

Introduction: Computational models using data from high-throughput screening assays have promise for prioritizing and screening chemicals for testing under the U.S. Environmental Protection Agency's Endocrine Disruptor Screening Program (EDSP). The purpose of this work was to demonstrate a data processing method for the determination of optimal minimal assay batteries from a larger comprehensive model, to provide a uniform method of evaluating the performance of future minimal assay batteries compared with the androgen receptor (AR) pathway model, and to incorporate chemical cluster analysis into this evaluation. Although several of the assays in the AR pathway model are no longer available through the original vendor, this approach could be used for future evaluations of minimal assay models for prioritization and screening. Methods: We compared two previously published models and found that an expanded 14-assay model had higher sensitivity for antagonists, whereas the original 11-assay model had slightly higher sensitivity for agonists. We then investigated subsets of assays in the original AR pathway model to optimize overall testing strategies that minimize cost while maintaining sensitivity across a broad chemical space. Results and Discussion: Evaluation of the critical assays across subset models derived from the 14-assay model identified three critical assays for predicting antagonism and two critical assays for predicting agonism. A minimum of nine assays is required for predicting agonism and antagonism with high sensitivity (95%). However, testing workflows guided by chemical structure-based clusters can reduce the average number of assays needed per chemical by basing the assays selected for testing on the likelihood of a chemical being an AR agonist, according to its structure. Our results show that a multi-stage testing workflow can provide 95% sensitivity while requiring only 48% of the resources required for running all assays from the original full models. The resources can be reduced further by incorporating in silico activity predictions. Conclusion: This work illustrates a data-driven approach that incorporates chemical clustering and simultaneous consideration of antagonism and agonism mechanisms to more efficiently screen chemicals. This case study provides a proof of concept for prioritization and screening strategies that can be utilized in future analyses to minimize the overall number of assays needed for predicting AR activity, which will maximize the number of chemicals that can be tested and allow data-driven prioritization of chemicals for further screening under the EDSP.

Systematic update to the mammalian relative potency estimate database and development of best estimate toxic equivalency factors for dioxin-like compounds

The World Health Organization (WHO) assesses potential health risks of dioxin-like compounds using Toxic Equivalency Factors (TEFs). This study systematically updated the relative potency (REP) database underlying the 2005 WHO TEFs and applied advanced methods for quantitative integration of study quality and dose-response. Data obtained from fifty-one publications more than doubled the size of the previous REP database (∼1300 datasets). REP quality and relevance for these data was assessed via application of a consensus-based weighting framework. Using Bayesian dose-response modeling, available data were modeled to produce standardized dose/concentration-response Hill curves. Study quality and REP data were synthesized via Bayesian meta-analysis to integrate dose/concentration-response data, author-calculated REPs and benchmark ratios. The output is a prediction of the most likely relationship between each congener and its reference as model-predicted TEF uncertainty distributions, or the 'best estimate TEF' (BE-TEF). The resulting weighted BE-TEFs were similar to the 2005 TEFs, though provide more information to inform selection of TEF values as well as to provide risk assessors and managers with information needed to quantitatively characterize uncertainty around TEF values. Collectively, these efforts produce an updated REP database and an objective, reproducible approach to support development of TEF values based on all available data.

Development and application of a systematic and quantitative weighting framework to evaluate the quality and relevance of relative potency estimates for dioxin-like compounds (DLCs) for human health risk assessment

The toxic equivalency factors (TEFs) approach for dioxin-like chemicals (DLCs) is currently based on a qualitative assessment of a heterogeneous data set of relative estimates of potency (REPs) spanning several orders of magnitude with highly variable study quality and relevance. An effort was undertaken to develop a weighting framework to systematically evaluate and quantitatively integrate the quality and relevance for development of more robust TEFs. Six main-study characteristics were identified as most important in characterizing the quality and relevance of an individual REP for human health risk assessment: study type, study model, pharmacokinetics, REP derivation method, REP derivation quality, and endpoint. Subsequently, a computational approach for quantitatively integrating the weighting framework parameters was developed and applied to the REP2004 database. This was accomplished using a machine learning approach which infers a weighted TEF distribution for each congener. The resulting database, weighted for quality and relevance, provides REP distributions from >600 data sets (including in vivo and in vitro studies, a range of endpoints, etc.). This weighted database provides a flexible platform for systematically and objectively characterizing TEFs for use in risk assessment, as well as providing information to characterize uncertainty and variability. Collectively, this information provides risk managers with information for decision making.

A multi-tiered hierarchical Bayesian approach to derive toxic equivalency factors for dioxin-like compounds

In 2005, the World Health Organization (WHO) re-evaluated Toxic Equivalency factors (TEFs) developed for dioxin-like compounds believed to act through the Ah receptor based on an updated database of relative estimated potency (REP)(REP2004 database). This re-evalution identified the need to develop a consistent approach for dose-response modeling. Further, the WHO Panel discussed the significant heterogeneity of experimental datasets and dataset quality underlying the REPs in the database. There is a critical need to develop a quantitative, and quality weighted approach to characterize the TEF for each congener. To address this, a multi-tiered approach that combines Bayesian dose-response fitting and meta-regression with a machine learning model to predict REPS' quality categorizations was developed to predict the most likely relationship between each congener and its reference and derive model-predicted TEF uncertainty distributions. As a proof of concept, this 'Best-Estimate TEF workflow' was applied to the REP2004 database to derive TEF point-estimates and characterizations of uncertainty for all congeners. Model-TEFs were similar to the 2005 WHO TEFs, with the data-poor congeners having larger levels of uncertainty. This transparent and reproducible computational workflow incorporates WHO expert panel recommendations and represents a substantial improvement in the TEF methodology.

Cutting-edge computational chemical exposure research at the U.S. Environmental Protection Agency

Exposure science is evolving from its traditional "after the fact" and "one chemical at a time" approach to forecasting chemical exposures rapidly enough to keep pace with the constantly expanding landscape of chemicals and exposures. In this article, we provide an overview of the approaches, accomplishments, and plans for advancing computational exposure science within the U.S. Environmental Protection Agency's Office of Research and Development (EPA/ORD). First, to characterize the universe of chemicals in commerce and the environment, a carefully curated, web-accessible chemical resource has been created. This DSSTox database unambiguously identifies >1.2 million unique substances reflecting potential environmental and human exposures and includes computationally accessible links to each compound's corresponding data resources. Next, EPA is developing, applying, and evaluating predictive exposure models. These models increasingly rely on data, computational tools like quantitative structure activity relationship (QSAR) models, and machine learning/artificial intelligence to provide timely and efficient prediction of chemical exposure (and associated uncertainty) for thousands of chemicals at a time. Integral to this modeling effort, EPA is developing data resources across the exposure continuum that includes application of high-resolution mass spectrometry (HRMS) non-targeted analysis (NTA) methods providing measurement capability at scale with the number of chemicals in commerce. These research efforts are integrated and well-tailored to support population exposure assessment to prioritize chemicals for exposure as a critical input to risk management. In addition, the exposure forecasts will allow a wide variety of stakeholders to explore sustainable initiatives like green chemistry to achieve economic, social, and environmental prosperity and protection of future generations.

The chemical landscape of high-throughput new approach methodologies for exposure

The rapid characterization of risk to humans and ecosystems from exogenous chemicals requires information on both hazard and exposure. The U.S. Environmental Protection Agency's ToxCast program and the interagency Tox21 initiative have screened thousands of chemicals in various high-throughput (HT) assay systems for in vitro bioactivity. EPA's ExpoCast program is developing complementary HT methods for characterizing the human and ecological exposures necessary to interpret HT hazard data in a real-world risk context. These new approach methodologies (NAMs) for exposure include computational and analytical tools for characterizing multiple components of the complex pathways chemicals take from their source to human and ecological receptors. Here, we analyze the landscape of exposure NAMs developed in ExpoCast in the context of various chemical lists of scientific and regulatory interest, including the ToxCast and Tox21 libraries and the Toxic Substances Control Act (TSCA) inventory. We examine the landscape of traditional and exposure NAM data covering chemical use, emission, environmental fate, toxicokinetics, and ultimately external and internal exposure. We consider new chemical descriptors, machine learning models that draw inferences from existing data, high-throughput exposure models, statistical frameworks that integrate multiple model predictions, and non-targeted analytical screening methods that generate new HT monitoring information. We demonstrate that exposure NAMs drastically improve the coverage of the chemical landscape compared to traditional approaches and recommend a set of research activities to further expand the development of HT exposure data for application to risk characterization. Continuing to develop exposure NAMs to fill priority data gaps identified here will improve the availability and defensibility of risk-based metrics for use in chemical prioritization and screening. IMPACT: This analysis describes the current state of exposure assessment-based new approach methodologies across varied chemical landscapes and provides recommendations for filling key data gaps.

Development of the InTelligence And Machine LEarning (TAME) Toolkit for Introductory Data Science, Chemical-Biological Analyses, Predictive Modeling, and Database Mining for Environmental Health Research

Research in environmental health is becoming increasingly reliant upon data science and computational methods that can more efficiently extract information from complex datasets. Data science and computational methods can be leveraged to better identify relationships between exposures to stressors in the environment and human disease outcomes, representing critical information needed to protect and improve global public health. Still, there remains a critical gap surrounding the training of researchers on these in silico methods. We aimed to address this gap by developing the inTelligence And Machine lEarning (TAME) Toolkit, promoting trainee-driven data generation, management, and analysis methods to “TAME” data in environmental health studies. Training modules were developed to provide applications-driven examples of data organization and analysis methods that can be used to address environmental health questions. Target audiences for these modules include students, post-baccalaureate and post-doctorate trainees, and professionals that are interested in expanding their skillset to include recent advances in data analysis methods relevant to environmental health, toxicology, exposure science, epidemiology, and bioinformatics/cheminformatics. Modules were developed by study coauthors using annotated script and were organized into three chapters within a GitHub Bookdown site. The first chapter of modules focuses on introductory data science, which includes the following topics: setting up R/RStudio and coding in the R environment; data organization basics; finding and visualizing data trends; high-dimensional data visualizations; and Findability, Accessibility, Interoperability, and Reusability (FAIR) data management practices. The second chapter of modules incorporates chemical-biological analyses and predictive modeling, spanning the following methods: dose-response modeling; machine learning and predictive modeling; mixtures analyses; -omics analyses; toxicokinetic modeling; and read-across toxicity predictions. The last chapter of modules was organized to provide examples on environmental health database mining and integration, including chemical exposure, health outcome, and environmental justice indicators. Training modules and associated data are publicly available online (https://uncsrp.github.io/Data-Analysis-Training-Modules/). Together, this resource provides unique opportunities to obtain introductory-level training on current data analysis methods applicable to 21st century science and environmental health.

Measuring interoception: The phase adjustment task

Interoception, perception of one's bodily state, has been associated with mental health and socio-emotional processes. However, several interoception tasks are of questionable validity, meaning associations between interoception and other variables require confirmation with new measures. Here we describe the novel, smartphone-based Phase Adjustment Task (PAT). Tones are presented at the participant's heart rate, but out of phase with heartbeats. Participants adjust the phase relationship between tones and heartbeats until they are synchronous. Data from 124 participants indicates variance in performance across participants which is not affected by physiological or strategic confounds. Associations between interoception and anxiety, depression and stress were not significant. Weak associations between interoception and mental health variables may be a consequence of testing a non-clinical sample. A second study revealed PAT performance to be moderately stable over one week, consistent with state effects on interoception.

Comparing the Predictivity of Human Placental Gene, microRNA, and CpG Methylation Signatures in Relation to Perinatal Outcomes

Molecular signatures are being increasingly integrated into predictive biology applications. However, there are limited studies comparing the overall predictivity of transcriptomic vs. epigenomic signatures in relation to perinatal outcomes. This study set out to evaluate mRNA and microRNA (miRNA) expression and cytosine-guanine dinucleotide (CpG) methylation signatures in human placental tissues and relate these to perinatal outcomes known to influence maternal/fetal health; namely, birth weight, placenta weight, placental damage, and placental inflammation. The following hypotheses were tested: (1) different molecular signatures will demonstrate varying levels of predictivity towards perinatal outcomes, and (2) these signatures will show disruptions from an example exposure (i.e., cadmium) known to elicit perinatal toxicity. Multi-omic placental profiles from 390 infants in the Extremely Low Gestational Age Newborns cohort were used to develop molecular signatures that predict each perinatal outcome. Epigenomic signatures (i.e., miRNA and CpG methylation) consistently demonstrated the highest levels of predictivity, with model performance metrics including R^2 (predicted vs. observed) values of 0.36-0.57 for continuous outcomes and balanced accuracy values of 0.49-0.77 for categorical outcomes. Top-ranking predictors included miRNAs involved in injury and inflammation. To demonstrate the utility of these predictive signatures in screening of potentially harmful exogenous insults, top-ranking miRNA predictors were analyzed in a separate pregnancy cohort and related to cadmium. Key predictive miRNAs demonstrated altered expression in association with cadmium exposure, including miR-210, known to impact placental cell growth, blood vessel development, and fetal weight. These findings inform future predictive biology applications, where additional benefit will be gained by including epigenetic markers.

Predictive modeling of biological responses in the rat liver using in vitro Tox21 bioactivity: Benefits from high-throughput toxicokinetics

Computational methods are needed to more efficiently leverage data from in vitro cell-based models to predict what occurs within whole body systems after chemical insults. This study set out to test the hypothesis that in vitro high-throughput screening (HTS) data can more effectively predict in vivo biological responses when chemical disposition and toxicokinetic (TK) modeling are employed. In vitro HTS data from the Tox21 consortium were analyzed in concert with chemical disposition modeling to derive nominal, aqueous, and intracellular estimates of concentrations eliciting 50% maximal activity. In vivo biological responses were captured using rat liver transcriptomic data from the DrugMatrix and TG-Gates databases and evaluated for pathway enrichment. In vivo dosing data were translated to equivalent body concentrations using HTTK modeling. Random forest models were then trained and tested to predict in vivo pathway-level activity across 221 chemicals using in vitro bioactivity data and physicochemical properties as predictor variables, incorporating methods to address imbalanced training data resulting from high instances of inactivity. Model performance was quantified using the area under the receiver operator characteristic curve (AUC-ROC) and compared across pathways for different combinations of predictor variables. All models that included toxicokinetics were found to outperform those that excluded toxicokinetics. Biological interpretation of the model features revealed that rather than a direct mapping of in vitro assays to in vivo pathways, unexpected combinations of multiple in vitro assays predicted in vivo pathway-level activities. To demonstrate the utility of these findings, the highest-performing model was leveraged to make new predictions of in vivo biological responses across all biological pathways for remaining chemicals tested in Tox21 with adequate data coverage (n = 6617). These results demonstrate that, when chemical disposition and toxicokinetics are carefully considered, in vitro HT screening data can be used to effectively predict in vivo biological responses to chemicals.

Development of a Range of Plausible Noncancer Toxicity Values for 2,3,7,8-Tetrachlorodibenzo-p-Dioxin Based on Effects on Sperm Count: Application of Systematic Review Methods and Quantitative Integration of Dose Response Using Meta-Regression

Regulatory agencies have derived noncancer toxicity values for 2,3,7,8-tetrachlorodibenzo-p-dioxin based on reduced sperm counts relying on single studies from a large body of evidence. Techniques such as meta-regression allow for greater use of the available data while simultaneously providing important information regarding the uncertainty associated with the underlying evidence base when conducting risk assessments. The objective herein was to apply systematic review methods and meta-regression to characterize the dose-response relationship of gestational exposure and epididymal sperm count. Twenty-three publications (20 animal studies consisting of 29 separate rat experimental data sets, and 3 epidemiology studies) met inclusion criteria. Risk of bias evaluation was performed to critically appraise study validity. Low to very low confidence precluded use of available epidemiological data as candidate studies for dose-response due to inconsistencies across the evidence base, high risk of bias, and general lack of biological coherence, including lack of clinical relevance and dose-response concordance. Experimental animal studies, which were found to have higher confidence following the structured assessment of confidence (eg, controlled exposure, biological consistency), were used as the basis of a meta-regression. Multiple models were fit; points of departure were identified and converted to human equivalent doses. The resulting reference dose estimates ranged from approximately 4 to 70 pg/kg/day, depending on model, benchmark response level, and study validity integration approach. This range of reference doses can be used either qualitatively or quantitatively to enhance understanding of human health risk estimates for dioxin-like compounds.

Application of qualitative and quantitative uncertainty assessment tools in developing ranges of plausible toxicity values for 2,3,7,8-tetrachlorodibenzo-p-dioxin

Increasing interest in characterizing risk assessment uncertainty is highlighted by recent recommendations from the National Academy of Sciences. In this paper we demonstrate the utility of applying qualitative and quantitative methods for assessing uncertainty to enhance risk-based decision-making for 2,3,7,8-tetrachlorodibenzo-p-dioxin. The approach involved deconstructing the reference dose (RfD) via evaluation of the different assumptions, options, models and methods associated with derivation of the value, culminating in the development of a plausible range of potential values based on such areas of uncertainty. The results demonstrate that overall RfD uncertainty was high based on limitations in the process for selection (e.g., compliance with inclusion criteria related to internal validity of the co-critical studies, consistency with other studies), external validity (e.g., generalizing findings of acute, high-dose exposure scenarios to the general population), and selection and classification of the point of departure using data from the individual studies (e.g., lack of statistical and clinical significance). Building on sensitivity analyses conducted by the US Environmental Protection Agency in 2012, the resulting estimates of RfD values that account for the uncertainties ranged from ~1.5 to 179 pg/kg/day. It is anticipated that the range of RfDs presented herein, along with the characterization of uncertainties, will improve risk assessments of dioxins and provide important information to risk managers, because reliance on a single toxicity value limits the information needed for making decisions and gives a false sense of precision and accuracy.

Assessing children's exposure to manganese in drinking water using a PBPK model

A previously published human PBPK model for manganese (Mn) in infants and children has been updated with Mn in drinking water as an additional exposure source. Built upon the ability to capture differences in Mn source-specific regulation of intestinal uptake in nursing infants who are breast-fed and formula-fed, the updated model now describes the bioavailability of Mn from drinking water in children of ages 0-18. The age-related features, including the recommended age-specific Mn dietary intake, age-specific water consumption rates, and age-specific homeostasis of Mn, are based on the available human data and knowledge of the biology of essential-metal homeostasis. Model simulations suggest that the impact of adding drinking-water exposure to daily Mn exposure via dietary intake and ambient air inhalation in children is not greater than the impacts in adults, even at a drinking-water concentration that is 2 times higher than the USEPA's lifetime health advisory value. This conclusion was also valid for formula-fed infants who are considered at the highest potential exposure to Mn from drinking water compared to all other age groups. Our multi-route, multi-source Mn PBPK model for infants and children provides insights about the potential for Mn-related health effects on growing children and will thereby improve the level of confidence in properly interpreting Mn exposure-health effects relationships in children in human epidemiological studies.

Development of an oral reference dose for the perfluorinated compound GenX

Ammonium 2,3,3,3‐tetrafluoro‐2‐(heptafluoropropoxy)‐propanoate, also known as GenX, is a processing aid used in the manufacture of fluoropolymers. GenX is one of several chemistries developed as an alternative to long‐chain poly‐fluoroalkyl substances, which tend to have long clearance half‐lives and are environmentally persistent. Unlike poly‐fluoroalkyl substances, GenX has more rapid clearance, but has been detected in US and international water sources. There are currently no federal drinking water standards for GenX in the USA; therefore, we developed a non‐cancer oral reference dose (RfD) for GenX based on available repeated dose studies. The review of the available data indicate that GenX is unlikely to be genotoxic. A combination of traditional frequentist benchmark dose models and Bayesian benchmark dose models were used derive relevant points of departure from mammalian toxicity studies. In addition, deterministic and probabilistic RfD values were developed using available tools and regulatory guidance. The two approaches resulted in a narrow range of RfD values for liver lesions observed in a 2‐year bioassay in rats (0.01–0.02 mg/kg/day). The probabilistic approach resulted in the lower, i.e., more conservative RfD. The probabilistic RfD of 0.01 mg/kg/day results in a maximum contaminant level goal of 70 ppb. It is anticipated that these values, along with the hazard identification and dose‐response modeling described herein, should be informative for risk assessors and regulators interested in setting health‐protective drinking water guideline values for GenX.

Ammonium 2,3,3,3‐tetrafluoro‐2‐(heptafluoropropoxy)‐propanoate, also known as GenX, is a processing aid used in the manufacture of fluoropolymers. There are currently no federal drinking water standards for GenX in the USA. Frequentist benchmark dose models and Bayesian benchmark dose models were used to derive points of departure from mammalian toxicity studies. Deterministic and probabilistic reference dose values were developed and resulted in a narrow range of values (0.01‐0.02 mg/kg/day). The lower reference dose results in a maximum contaminant level goal of 70 ppb.

Bioaccessibility and relative oral bioavailability of cobalt and nickel in residential soil and dust affected by metal grinding operations

Including measures of relative bioavailability (RBA) improves the accuracy of site-specific risk assessment when evaluating metals bound in matrices that resist acid digestion (alloys, slag, tailings). In vitro gastrointestinal bioaccessibility and in vivo RBA assessments were conducted using baghouse dust, surface dust, and soil collected in a neighborhood near a metal forge, which emitted metals in the form of corrosion resistant alloys. The study objective was to characterize the in vitro bioaccessibility and relative bioavailability (RBA) of cobalt and nickel when ingested as freely soluble forms (ionic salts used as the basis for oral toxicity criteria), compared to when incidentally ingested in the forms found in the environment. Test materials and standard reference materials-cobalt chloride and nickel sulfate-were administered daily for 14 or 21 days, twice daily, to juvenile swine. Daily intake doses for cobalt were ≤229 μg/kg-day, and for nickel, ≤1419 μg/kg-day. Concentrations of cobalt and nickel were measured in various tissues; 24-hour urinary excretion of each metal was also measured. Multiple linear regression modeling was performed for tissue concentration or urinary excretion vs. dose in each material, with weighting as inverse variance in each dose group. Liver, urine, and kidney provided the optimal data. Although RBA values were affected by limited absolute bioavailability of cobalt and nickel in reference materials, trends across the different biological matrices consistently showed significantly reduced bioavailability of cobalt and nickel in soil and dust, with RBAs ranging from 0.2% to 12%. Bioaccessibility of cobalt and nickel in soil and dust were 1% to 5%, and similar results were found for baghouse dust. The data demonstrate that cobalt and nickel in soil and dust affected by alloys are resistant to bioelution and absorption. This study provides useful information for site-specific risk assessments and insights for planning future research.

Identifying Attributes That Influence In Vitro-to-In Vivo Concordance by Comparing In Vitro Tox21 Bioactivity Versus In Vivo DrugMatrix Transcriptomic Responses Across 130 Chemicals

Recent efforts aimed at integrating in vitro high-throughput screening (HTS) data into chemical toxicity assessments are necessitating increased understanding of concordance between chemical-induced responses observed in vitro versus in vivo. This investigation set out to (1) measure concordance between in vitro HTS data and transcriptomic responses observed in vivo, focusing on the liver, and (2) identify attributes that can influence concordance. Signal response profiles from 130 substances were compared between in vitro data produced through Tox21 and liver transcriptomic data through DrugMatrix, collected from rats exposed to a chemical for ≤5 days. A global in vitro-to-in vivo comparative analysis based on pathway-level responses resulted in an overall average percent agreement of 79%, ranging on a per-chemical basis between 41% and 100%. Whereas concordance amongst inactive chemicals was high (89%), concordance amongst chemicals showing in vitro activity was only 13%, suggesting that follow-up in vivo and/or orthogonal in vitro assays would improve interpretations of in vitro activity. Attributes identified to influence concordance included experimental design attributes (eg, cell type), target pathways, and physicochemical properties (eg, logP). The attribute that most consistently increased concordance was dose applicability, evaluated by filtering for experimental doses administered to rats that were within 10-fold of those related to likely bioactivity, derived using Tox21 data and high-throughput toxicokinetic modeling. Together, findings suggest that in vitro screening approaches to predict in vivo toxicity are viable particularly when certain attributes are considered, including whether activity versus inactivity is observed, experimental design, chemical properties, and dose applicability.

In vitro to in vivo extrapolation for high throughput prioritization and decision making

In vitro chemical safety testing methods offer the potential for efficient and economical tools to provide relevant assessments of human health risk. To realize this potential, methods are needed to relate in vitro effects to in vivo responses, i.e., in vitro to in vivo extrapolation (IVIVE). Currently available IVIVE approaches need to be refined before they can be utilized for regulatory decision-making. To explore the capabilities and limitations of IVIVE within this context, the U.S. Environmental Protection Agency Office of Research and Development and the National Toxicology Program Interagency Center for the Evaluation of Alternative Toxicological Methods co-organized a workshop and webinar series. Here, we integrate content from the webinars and workshop to discuss activities and resources that would promote inclusion of IVIVE in regulatory decision-making. We discuss properties of models that successfully generate predictions of in vivo doses from effective in vitro concentration, including the experimental systems that provide input parameters for these models, areas of success, and areas for improvement to reduce model uncertainty. Finally, we provide case studies on the uses of IVIVE in safety assessments, which highlight the respective differences, information requirements, and outcomes across various approaches when applied for decision-making.

Physiologically based pharmacokinetic model for ethyl tertiary-butyl ether and tertiary-butyl alcohol in rats: Contribution of binding to α2u-globulin in male rats and high-exposure nonlinear kinetics to toxicity and cancer outcomes

In cancer bioassays, inhalation, but not drinking water exposure to ethyl tertiary-butyl ether (ETBE), caused liver tumors in male rats, while tertiary-butyl alcohol (TBA), an ETBE metabolite, caused kidney tumors in male rats following exposure via drinking water. To understand the contribution of ETBE and TBA kinetics under varying exposure scenarios to these tumor responses, a physiologically based pharmacokinetic model was developed based on a previously published model for methyl tertiary-butyl ether, a structurally similar chemical, and verified against the literature and study report data. The model included ETBE and TBA binding to the male rat-specific protein α2u-globulin, which plays a role in the ETBE and TBA kidney response observed in male rats. Metabolism of ETBE and TBA was described as a single, saturable pathway in the liver. The model predicted similar kidney AUC_0-∞ for TBA for various exposure scenarios from ETBE and TBA cancer bioassays, supporting a male-rat-specific mode of action for TBA-induced kidney tumors. The model also predicted nonlinear kinetics at ETBE inhalation exposure concentrations above ~2000 ppm, based on blood AUC_0-∞ for ETBE and TBA. The shift from linear to nonlinear kinetics at exposure concentrations below the concentration associated with liver tumors in rats (5000 ppm) suggests the mode of action for liver tumors operates under nonlinear kinetics following chronic exposure and is not relevant for assessing human risk. Copyright © 2016 The Authors Journal of Applied Toxicology Published by John Wiley & Sons Ltd.

PESI - a taxonomic backbone for Europe

Background

Reliable taxonomy underpins communication in all of biology, not least nature conservation and sustainable use of ecosystem resources. The flexibility of taxonomic interpretations, however, presents a serious challenge for end-users of taxonomic concepts. Users need standardised and continuously harmonised taxonomic reference systems, as well as high-quality and complete taxonomic data sets, but these are generally lacking for non-specialists. The solution is in dynamic, expertly curated web-based taxonomic tools.

The Pan-European Species-directories Infrastructure (PESI) worked to solve this key issue by providing a taxonomic e-infrastructure for Europe. It strengthened the relevant social (expertise) and information (standards, data and technical) capacities of five major community networks on taxonomic indexing in Europe, which is essential for proper biodiversity assessment and monitoring activities. The key objectives of PESI were: 1) standardisation in taxonomic reference systems, 2) enhancement of the quality and completeness of taxonomic data sets and 3) creation of integrated access to taxonomic information.

New information

This paper describes the results of PESI and its future prospects, including the involvement in major European biodiversity informatics initiatives and programs.

Do early stages of lumbar intervertebral disc degeneration really cause instability? Evaluation of an in vitro database

Early stages of intervertebral disc degeneration are postulated to cause instability. In the literature, however, some authors report the opposite. These contradictory positions are probably supported by the mostly small number of segments which are investigated. The aim of this project therefore was to investigate the influence of intervertebral disc degeneration on lumbar spine rotational stability using a large data set. The flexibility data from all spine specimens tested in our institute so far were collected in a large in vitro database. From this database, all lumbar spine specimens were selected, which had been tested for flexibility under pure moment loads of ±7.5 N m and for which radiographs were accessible. 203 segments met these criteria. Their radiographic degree of disc degeneration was determined on a scale from 0 (no degeneration) to 3 (severe degeneration) and their influence on the respective range of motion and neutral zone was examined. The different lumbar levels differ in flexibility, which increases the variability of the data if pooled together. To minimise this effect a statistical model was fitted. The model-based mean estimates showed a decrease of the range of motion from grade 0 to 3 in flexion/extension (by 3.1°, p < 0.05) and lateral bending (by 3.4°, p < 0.05). In contrast, in axial rotation the range of motion tended to increase; however, not only from grade 0 to 1 but also towards grade 3 (by 0.2°) (p > 0.05). The neutral zone was affected in a similar way but to a smaller degree (p > 0.05). In conclusion, the results indicated that early stages of intervertebral disc degeneration do not necessarily cause rotational instability. In contrast, stability increased in flexion/extension and lateral bending. Only in axial rotation stability tended to decrease.

[Improvement of anxiety and depression in women with breast cancer during inpatient oncological rehabilitation-- results of a prospective study]

PURPOSE

Investigation of the influence of an oncological inpatient rehabilitation programme on anxiety and depression in women with breast cancer.

PATIENTS AND METHOD

198 women with breast cancer, aged 25 to 75 years, filled in the Hospital Anxiety and Depression Scale (HADS) German version at the beginning and end of inpatient rehabilitation. Focus was set on the frequency of anxiety and depression. Therefore proportions with 95 % confidence intervals (CI) were built. The before-after comparison of HADS-scores was made using the signed rank test with two-sided level of significance of alpha = 5 %. In addition effect sizes were calculated. Possible relations between the scores at the beginning of rehabilitation and the patients' age or the interval since diagnosis were analysed by calculating correlation coefficients.

RESULTS

At the beginning of rehabilitation a state of anxiety was probable in 23.2 % (CI [17.3 %; 29.1 %] of the women and one of depression in 9.1 % (CI [5.8 %; 13.9 %]). In other words, they reached a level of >or= 11 score points on each scale. No correlation was found with the age of the patients or the time interval since diagnosis (|r| <or= 0.192). At the end of rehabilitation 67.5 % (CI [61.0 %; 74.0 %]) and 60.9 % (CI [54.1 %; 67.7 %]), respectively, of the women showed an improvement of anxiety and depression. The before-after difference was a median + 2 points (anxiety) and + 1 point (depression), resp., with a positive value representing an improvement. The changes after rehabilitation were statistically significant with p < 0.0001. The effect sizes ranged from 0.37 to 0.50.

CONCLUSIONS

After the end of primary therapy, women with breast cancer frequently suffer from anxiety or depressive disorders, with no correlation to the patients' age or time since diagnosis. By an inpatient oncological rehabilitation programme both anxiety and depression can be improved very successfully. Whether these results represent a long-term effect is currently being evaluated in a randomised prospective study.

[Prediction of premature pension after stationary rehabilitation due to adipositas--a prognostic model based on routinely collected data of the State Insurance Institution of Baden-Württemberg]

Up to 60 % of the German population can be marked as obese. Due is to its frequency and its associated diseases like cardiovascular disorders and disorders of the musculoskeletal system adipositas is a severe burden on the German health care system. This burden is caused by costs of the disease and costs due to premature pensioning. In this study logistic regression modelling has been performed by means of routinely collected data of patients of the regional statutory pension insurance institute Landesversicherungsanstalt Baden-Württemberg (LVA-BW) rehabilitated due to adipositas (n = 599). The aim was to detect influential variables for the prognosis of premature pensioning (n = 135). The data of the patients were obtained from a research database of the "RehaNet" project which includes data of the standardized discharge report of the Federation of German Pension Insurance Institutes and quality assurance questionnaires of the LVA-BW. Three variables remain in the model after a step-down procedure for modelling by logistic regression. The selected variables are age (in years), the physician's statement about the patients limitations of movement after rehabilitation (yes/no) and about the patients ability to work in future (more/less than half-day). After internal validation of the model by bootstrap methods the model achieves a sensitivity of 73 %, a specificity of 87 %, a positive and a negative predictive value of 57 and 93 % respectively. The area under the curve (AUC) of the ROC analysis is 0.87, so the model achieves a good prognostic value. Thus, this model is a valuable test for the exclusion of possible premature pension while or after rehabilitation due to adipositas. It was found that the situation of "no premature pensioning" of patients rehabilitated due to adipositas can be predicted quite accurately with little information (three variables). This reveals a perspective for further research in the possibility of an early, risk-adapted and individualised intervention after stationary rehabilitation for adipositas to keep employment.

A randomized trial of Korodin Herz-Kreislauf-Tropfen as add-on treatment in older patients with orthostatic hypotension

In a randomized, double-blind, placebo-controlled, parallel group, phase III clinical trial efficacy and safety of Korodin, a combination of natural D-camphor and an extract from fresh crataegus berries, was investigated in patients 50 years and older with orthostatic hypotension. At visit 1 eligibility of patients was checked and a placebo medication was given to all patients. At visit 2 orthostatic hypotension had to be reconfirmed, then the patient was randomized either to Korodin or placebo, study medication (25 drops) was applied once and then outcome was measured. After 7 days of home treatment with daily 3 x 25 drops outcome was measured at visit 3. Systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) were documented 10, 5, 2 and 0 min before as well as 1, 3, 5, 8, and 10 min after getting in the upright position at visit 1, at visit 2 before and after application of study medication and at visit 3. Primary outcome was the change of mean arterial blood pressure (MAP) from just before standing up to the nadir within the first 3 min after standing up. Secondary outcome variables were SBP, DBP, HR, quality of life (SF-12) and seven typical signs and symptoms of orthostatic hypotension. The study was performed in a rehabilitation clinic and in two doctor's practices in Germany from November 2002 to May 2003. During this time, 57 patients were admitted to the study, 39 patients were eligible and randomized, 38 patients were treated according to protocol and evaluated, 21 patients with Korodin and 17 patients with placebo. After a single application the median decrease of MAP was 11.4 mmHg for Korodin and 14.0 mmHg for placebo. Compared to baseline, the median MAP improved 4.3 mmHg for Korodin and 0.3 mmHg for placebo. After 1 week of treatment the decrease of median MAP after standing up was 9.3 mmHg for Korodin and 13.3 mmHg for placebo. Compared to baseline, the improvement was 5.9 mmHg for Korodin and 1.6 mmHg for placebo. Efficacy of 1 week treatment was significant. For the single application a superiority of Korodin over placebo was seen; however, it was not significant. All secondary outcome variables confirmed these findings, except for the physical summary score in the quality of life evaluation (SF-12 questionnaire). Only one adverse event occurred, but this was not serious and without relationship to the study medication. The other safety variables (SBP, DBP, HR, ECG, physical examination) did not show any problems. This study demonstrates that Korodin is efficacious for orthostatic hypotension in patients over 50 years.

Increased C reactive protein in response to acute stress in patients with rheumatoid arthritis

OBJECTIVE

To assess the effects of acute stress on inflammatory, haemostatic, rheological, and haemodynamic activity in patients with rheumatoid arthritis (RA) in comparison with patients with osteoarthritis (OA).

METHODS

21 patients with RA and 10 with OA underwent a brief mental stress task while standing. Inflammatory, haemostatic, rheological, and haemodynamic variables were measured at baseline, during the task, and at recovery.

RESULTS

At baseline, erythrocyte sedimentation rate and fibrinogen were higher in RA than OA. White blood cell count, fibrinogen, blood pressure, and pulse rate increased, whereas prothrombin time and plasma volume decreased during the task in both patient groups. The stress task increased C reactive protein (CRP) only in patients with RA, and more specifically in those patients with RA with high disease activity.

CONCLUSIONS

The increase in the inflammatory marker CRP, which was specific to patients with RA, combined with the haemostatic, rheological, and haemodynamic reactions to the stress task, over and above the already high baseline levels, could underlie the increased risk for myocardial infarction in this vulnerable patient group.

Cardiac coping style, heartbeat detection, and the interpretation of cardiac events

OBJECTIVES

Vigilance to, and avoidance of, cardiac sensations and symptoms were explored in three studies.

DESIGN AND METHODS

In the first study, a self-report measure of cardiac vigilance and cardiac avoidance, the Cardiac Coping Inventory (CCI), was administered to 453 students, and its factor structure, internal consistency, and test-retest reliability were established. In the second, 31 undergraduates completed the CCI, and their cardioceptive sensitivity was measured on a heartbeat detection task. In a third study of 91 patients with suspected myocardial infarction, the role of coping styles in symptom interpretations was analysed.

RESULTS

Cardiac avoidance and vigilance were independent of general symptom reporting tendencies. Cardiac vigilance was negatively correlated with heartbeat detection. Among the patients, delay in seeking treatment was predicted by the perceived importance of chest pain, which was influenced by the intensity of chest pain and cardiac vigilance.

CONCLUSIONS

Although individuals high in cardiac vigilance do not seem to be good detectors of their heartbeats in the laboratory, they appear to attach importance to heart symptoms in real life, resulting in a health-protective behaviour.

Osteoporose bei chronisch entzündlichen Darmerkrankungen - Ergebnisse einer Umfrage an Mitgliedern der Deutschen M. Crohn und Colitis ulcerosa Vereinigung (DCCV)

INTRODUCTION

Osteoporosis is a frequent and clinically important complication in inflammatory bowel disease (IBD). Prevalence and risk factors have been examined in small numbers of patients. With a nationwide survey of members of the German Crohn's and Ulcerative Colitis Association (DCCV) we wanted to evaluate the situation in a larger group of patients.

METHODS

Questionnaires were sent with the autumn issue of the members journal to approx. 14,620 affected members of the DCCV. Items covered osteoporosis, clinical symptoms, anamnesis and sociodemographic topics. Results are presented as descriptive analysis and in a logistic regression analysis of factors contributing to the osteoporosis risk.

RESULTS

2,536 questionnaires could be used (17.3 %). Mean age and distribution concerning diagnosis and gender were comparable to the DCCV members in total. The prevalence of pathologic bone density was 62.3 % in those 1,265 patients (50.1 %) who underwent bone densitometry in the course of their disease. The analysis led to the following possible risk factors: disease activity (high chronic activity or more than 1 acute flare annually vs. remission, p < 0.001), lifetime steroid dosage > 10 g (p = 0.002), Crohn's disease vs. ulcerative colitis (p = 0.02), multiple bowel resection (p = 0.032), age (p = 0.018) and low body mass index (p = 0.034). 83.4 % of the patients with pathologic bone density received specific therapy, but most of those (63.5 %) were solely substituted with calcium and vitamin D.

CONCLUSION

This is the first study looking at epidemiology and risk factors of osteoporosis in a large study population of patients with inflammatory bowel disease. Although the prevalence may be overestimated due to selection bias in our study, osteoporosis is confirmed as a frequent and clinically relevant complication in IBD. Bone densitometry is recommended in those patients with one or more risk factors.

Elevated heels and adaptation to new shoes in frail elderly women

Footwear is supposed to have influence on postural control and is a potential aspect to address in the prevention of falls in the elderly. This study aimed to show whether measurements of static balance and gait are different with habitual shoes compared to new special senior shoes with different heel height and whether these results change after adaptation. In a randomized controlled intervention study, 26 subjects (median age 87 years) were recruited from two nursing homes and one facility of assisted living. Measurements of static balance and gait were performed with habitual shoes and two types of new special senior shoes differing in heel height. Measurements were repeated after five weeks. There was no difference in static balance and gait with habitual shoes compared to either of the new footwear offered. Results of performance with higher heels were not different compared to lower heels. No further effect of adaptation after wearing a new shoe over five weeks could be demonstrated. With respect to static and dynamic balance, there seems to be a wide range of acceptable footwear as long as the heel height is below a critical value. A standardized shoe can be used in the assessment of balance because the effect of adaptation can be neglected.

Quality assurance in mental health-care: a case study from social work

The quality of health and social care is now a high priority for government, professionals, and the public. This is particularly true of mental health, where explicit standards lie at the centre of current policy, demanding the development of reliable means for quality assurance. These need to allow for the multiplicity of stakeholders in mental health-care, and their different constructions of "quality". The challenges presented are illustrated by this account of an action research programme, which was developed to improve social work practice in a multidisciplinary mental health service, and evaluated using a case study design. An action research approach was chosen in preference to an "off-the-shelf" quality assurance system, because it possessed features that appeared to match the context of the work. It involved feeding back the findings of a baseline assessment of service quality to four teams of social workers, who used the information to select priority areas for improvement. An action plan was developed with them, and its implementation and impact were examined. Substantial improvements were observed in only one of the chosen target areas--the quality of case recording. For the other--securing the clients' full involvement in their care plan--very limited improvements occurred. Interview data suggested that this was due to the presence of extensive organisational support for the first objective, but not the second. These findings suggest that while some features of action research can contribute to quality improvement, these must be incorporated into a more comprehensive programme of change, which commands the support of all the stakeholders involved.

Predictors of attendance at cardiac rehabilitation after myocardial infarction

OBJECTIVE

The purpose of this study was to determine predictors of attendance at cardiac rehabilitation after myocardial infarction (MI).

METHODS

Various demographic, behavioural, and clinical variables were measured during hospitalisation in 288 MI patients. Of these, 263 were available to attend outpatient-based cardiac rehabilitation: 108 actually attended.

RESULTS

Multiple logistic regression analyses indicated that nonattenders lived in more deprived areas and were less likely to have paid employment. Nonattenders also registered more symptoms of depression and anxiety and exercised less frequently prior to their MI, although only the last of these variables were predicted in a multivariate model. In terms of clinical status, whether patients had been thrombolysed or not was the strongest predictor of attendance.

CONCLUSIONS

Attendance at cardiac rehabilitation is not an arbitrary matter. Strategies should be developed for encouraging greater attendance among those not in paid employment, those from deprived areas, and those who exercise infrequently.

Prevalence of Staphylococcus aureus and staphylococcal enterotoxins in raw pork and uncooked smoked ham--a comparison of classical culturing detection and RFLP-PCR

In many countries Staphylococcus aureus is considered to be the second or third most common pathogen causing outbreaks of food poisoning, only outnumbered by Salmonella spp. and in competition with Clostridium perfringens. Often the consumption of ham or meat containing staphylococcal enterotoxins (SE) is identified as cause of the illness. Thus, to gain an insight into the prevalence of S. aureus and its emetic enterotoxins in raw pork and uncooked smoked ham and to investigate how the prevalence of the pathogen is influenced during the fabrication process, a total of 135 samples of raw pork, salted meat and ready-for-sale uncooked smoked ham were examined for the prevalence of S. aureus and staphylococcal enterotoxins A to D (SEA-SED). To this means classical cultural methods were employed as well as molecular biological techniques (PCR) and the results were compared. In 25.9% of all samples S. aureus was detected by culture whereas 51.1% of the samples showed a positive result when PCR was used for the detection of the pathogen. Fresh meat was contaminated most often. By PCR, 62.2% were identified as being S. aureus positive compared to 57.7% positive samples using the cultural technique. The detection rate during the fabrication process declined significantly. The pathogen was cultivated from 8.9% of the salted meat samples. Here, 55.6% of the samples reacted positively in the PCR, and finally, in approximately a third of the ready-for-sale smoked hams, S. aureus genes were found. From 11.1% of these samples, the pathogen could be isolated by culture. From these results, we conclude that the PCR used in this study is more sensitive than the classical cultural method. By PCR, one or more staphylococcal enterotoxin genes were found in 24 of the 135 examined samples. This means that 34.8% of the staphylococcal strains identified using the PCR technique were enterotoxigenic. Using the SET-RPLA, a percentage of 28.6% enterotoxigenic isolates was ascertained. No staphylococcal enterotoxin formation was detected by the SET-RPLA in ready-for-sale ham, although SE-genes were found by PCR. The detection of SE-genes by PCR is faster and easier to perform than the SET-RPLA.

Modulation of the human nociceptive flexion reflex across the cardiac cycle

Carotid baroreceptor stimulation has been shown to dampen pain. This study tested, in 40 normotensive adults, the hypothesis that pain is lower during systole when arterial baroreceptor stimulation is maximal than diastole when stimulation is minimal. The sural nerve was stimulated electrocutaneously to obtain a nociceptive flexion reflex (NFR) threshold, and then stimulation was delivered for 28 trials at 100% NFR threshold at seven intervals after the R-wave. Nociceptive responding was indexed by electromyographic (EMG) activity elicited in the biceps femoris. Significant variations in EMG activity occurred across the cardiac cycle, with less activity midcycle, indicating that the NFR response was attenuated during systole compared to diastole. Stimulation of baroreceptors by natural changes in blood pressure during the cardiac cycle dampened nociception, and accordingly, the data support the arterial baroreflex mechanism of hypertensive hypoalgesia.

The effects of competition and competitiveness on cardiovascular activity

Cardiovascular activity was measured at resting baseline and in response to a car racing game, undertaken in competition or in cooperation with an experimenter, or individually. Competitiveness and win and goal orientations were assessed by questionnaire. Competition provoked increases in blood pressure and heart rate, and a significant shortening of the preejection period, an index of enhanced beta-adrenergic influences on the heart. The cooperation task was largely without effect, and although the solo task affected cardiovascular activity, it did so to a lesser extent and much less consistently than did the competition task. The three task conditions, then, were largely distinguishable by their capacity to activate beta-adrenergic processes. Participants high in competitiveness and desire to win showed higher blood pressure reactions and greater shortening of the preejection period to competition than those low in these characteristics.

Changes in limb stiffness under conditions of mental stress

In 2 experiments, the effects of mental stress on limb stiffness were investigated. The relative contribution to arm stiffness of individual muscle activity, co-contraction, muscle reflexes, and postural adjustments were examined. In each experiment, participants (N = 24, Experiment 1; N = 16, Experiment 2) held their supinated hand under a tray that they were required to return to horizontal after it had been suddenly released. Electromyographic activity in the biceps and triceps muscles was recorded, as were elbow and wrist angles and tray displacement. In Experiment 1, mental arithmetic stress was shown to lead to decreased tray displacement (i.e., increased resistance) compared with displacements under the control, unstressed condition, as well as to increased elbow flexion before tray release. In Experiment 2, the increased resistance to perturbation caused by mental stress was found to be independent of initial elbow angle, but to vary as a function of the amount of upward force exerted before tray release. The authors conclude that stress-induced increases in limb stiffness result from changes in the initial position of the elbow, specified by its angle, together with the initial force exerted by participants to counteract the mechanical perturbations.

Mortality and quality of life 12 months after myocardial infarction: effects of depression and anxiety

OBJECTIVE

The purpose of this study was to determine the impact of symptoms of depression and anxiety on mortality and quality of life in patients hospitalized for acute myocardial infarction (MI).

METHODS

The Beck Depression Inventory and the State-Trait Anxiety Inventory were completed by 288 patients hospitalized for MI. Twelve-month survival status was ascertained, and quality of life among survivors was assessed at 12 months using the Dartmouth COOP charts.

RESULTS

Thirty-one (10.8%) patients died, 27 of cardiac causes, during the 12-month follow-up. Symptoms of depression and anxiety predicted neither cardiac nor all-cause mortality. Severity of infarction and evidence of heart failure predicted both cardiac and all-cause mortality. The same findings emerged from supplementary analyses of data from patients who died after discharge from the hospital. Symptoms of depression and anxiety, measured at entry, predicted 12-month quality of life among survivors, as did gender, partner status, employment status, living alone, previous frequency of exercise, and indices of disease severity (Killip class and Peel Index). In a multiple regression model in which all of these variables were entered, initial depression scores provided the best independent prediction of quality of life, although living alone, severity of infarction, and state anxiety also entered the model.

CONCLUSIONS

Symptoms of depression and anxiety did not predict either cardiac or all-cause mortality after MI, but they did predict quality of life among those who lived to 12 months.

Do depression and anxiety predict recurrent coronary events 12 months after myocardial infarction?

We examined the association between depression and anxiety and recurrent coronary heart disease events during the first 12 months subsequent to myocardial infarction. The Beck Depression Inventory and the State-Trait Anxiety Inventory were completed during hospitalization by 288 myocardial infarction patients. Peel Index score and Killip class were used as indices of disease severity. The 12-month incidence of recurrent coronary heart disease events (fatal and non-fatal) was determined. Eighty-two patients experienced recurrent coronary heart disease events, including 27 cardiac fatalities, during follow-up. Whereas the Peel Index differentiated patients who experienced recurrent events from those who did not (OR 3.00, 95% CI 1.46-6.20), symptoms of depression (OR 0.97, 95% CI 0. 55-1.70) and anxiety (OR 1.00, 95% CI 0.98-1.02) were unrelated to outcome. Depression and anxiety did not predict subsequent coronary heart disease events and were not associated with either Peel Index scores or Killip class.

Effects of depression and anxiety on mortality and quality-of-life 4 months after myocardial infarction

OBJECTIVE

The purpose of this study was to determine the impact of depression and anxiety on mortality and quality-of-life in patients hospitalized for an acute myocardial infarction (MI).

METHODS

Questionnaire measures of depression and anxiety were completed during hospitalization by 288 MI patients. The main outcomes were mortality and quality-of-life, assessed by the Dartmouth COOP charts, at 4 months.

RESULTS

A total of 25 patients died, 22 from cardiac causes, during the 4-month follow-up. Symptoms of depression and anxiety did not predict either cardiac or all-cause mortality. Severity of infarction, extent of heart failure, and a longer stay in hospital predicted mortality. Symptoms of depression and anxiety predicted 4-month quality-of-life among survivors, as did gender, partner status, occupational status, living alone, previous exercise behaviour, length of hospital admission, and Peel Index scores. In a multiple regression model, depression emerged as the strongest predictor of quality-of-life. State anxiety, severity of infarction, and partner status also entered the model.

CONCLUSION

Neither depression nor anxiety predicted mortality 4 months after MI. Both depression and anxiety predicted quality-of-life at 4 months among survivors.

Secretory immunoglobulin A and cardiovascular reactions to mental arithmetic, cold pressor, and exercise: effects of alpha-adrenergic blockade

The mechanism underlying acute changes in secretory immunoglobulin A (sIgA) remains to be determined. In this experiment, sIgA and cardiovascular activity were monitored at rest and while participants performed a mental arithmetic task, cold pressor, and submaximal cycle exercise following placebo or 1 mg of the alpha-adrenergic blocker, doxazosin. Under placebo, the tasks produced patterns of cardiovascular activity indicative of combined alpha- and beta-adrenergic, alpha-adrenergic, and beta-adrenergic activation, respectively. Doxazosin was associated with reduced blood pressure during cold pressor, but not during arithmetic or exercise. Mental arithmetic elicited increases in sIgA concentration and exercise produced increases in both sIgA concentration and secretion rate; these changes were unaffected by alpha blockade. In contrast, the cold pressor was associated with decreases in both sIgA concentration and secretion rate, which were blocked by doxazosin. These data suggest that acute decreases, but not increases, in sIgA are mediated by alpha-adrenergic mechanisms.

The effects of an oral multivitamin combination with calcium, magnesium, and zinc on psychological well-being in healthy young male volunteers: a double-blind placebo-controlled trial

RATIONALE

Vitamin and mineral supplements may be associated with improved psychological status.

OBJECTIVE

The present study tested the effects of a multivitamin and mineral supplement (Berocca) on psychological well-being.

METHODS

In a double-blind randomised-control trial, 80 healthy male volunteers were assigned to either Berocca or placebo. Questionnaires measuring psychological state were completed and a blood sample taken to determine plasma zinc concentration on day 1 (pre-treatment) and again on day 28 (post-treatment), following 28 days of treatments, which were administered at a dosage of one tablet daily. At the end of the study, the acceptability of the treatment and participants' awareness of treatment condition were assessed, as was habitual dietary behaviour.

RESULTS

Relative to placebo, treatment with Berocca was associated with consistent and statistically significant reductions in anxiety and perceived stress. Participants in the Berocca group also tended to rate themselves as less tired and better able to concentrate following treatment. In addition, participants registered more somatic symptoms following placebo than following Berocca. These effects cannot be attributed to differences in the acceptability of the two treatments or to participants guessing what treatment they received.

CONCLUSION

These findings demonstrate that Berocca significantly reduces anxiety and perceived stress.

Contributions of local and central sensations to the perception of exertion during cycling: effects of work rate and cadence

There is evidence to suggest that perception of exertion during exercise is based on both local and central sensations. The aim of the present experiment was to determine the relative contributions of different sensations to overall perceived exertion during cycling. Eighteen trained cyclists pedalled on a cycle ergometer for 4 min at each of three work rates (100, 150 and 200 W) and cadences (50, 70 and 90 rev x min(-1)). At the end of each bout, they used Borg's category-ratio (CR-10) scale to rate their overall perceived exertion, leg muscle pain, knee pain, breathlessness and heart beat intensity. The results indicated that cadence only influenced local sensations (muscle pain and knee pain), which were significantly higher at slower pedalling rates. Neither overall perceived exertion nor central sensations (breathlessness and heart beat intensity) were significantly affected by cadence. In contrast, increases in work rate were associated with higher ratings for all sensations. Further analyses revealed that variations in these overall ratings of perceived exertion as a function of work rate were accounted for by variations in ratings of muscle pain and breathlessness. The general implication is that perceived exertion during cycling derives from a combination of muscle and respiratory sensations.

Secretory immunoglobulin A and cardiovascular activity during mental arithmetic: effects of task difficulty and task order

Secretory immunoglobulin A (sIgA) in saliva and cardiovascular activity were measured at rest and during mental arithmetic. Task difficulty was manipulated by presenting easy, hard, and impossible versions of the mental arithmetic task in counterbalanced order, while task novelty was operationalised as order of presentation (i.e. first, second, third). Mental arithmetic elicited significant increases in sIgA concentration and sIgA secretion rate, as well as significant cardiovascular effects. Performance decreased and rated difficulty increased with increasing task difficulty. However, sIgA and cardiovascular activity, with the exception of diastolic blood pressure, were insensitive to variations in task difficulty. In contrast, sIgA concentration and a broad range of cardiovascular variables were influenced by task novelty, with more pronounced activity characterising the task version presented first, irrespective of its level of difficulty. Task novelty would seem to be a more important determinant of sIgA and cardiovascular activity than task difficulty.

Cardiovascular and secretory immunoglobulin A reactions to humorous, exciting, and didactic film presentations

Secretory immunoglobulin A (sIgA) in saliva and cardiovascular activity were measured at rest and in response to three film extracts varying in affective content. Subjective ratings of film impact confirmed a priori assumptions; the humorous film was rated as funnier than the other two films, the didactic film as more boring than the other two films, and the exciting film as more exciting and more stressful than the other two films. The films elicited distinct patterns of cardiovascular autonomic activity. The exciting film provoked changes characteristic of beta-adrenergic activation: increased systolic blood pressure (SBP); heart rate (HR); cardiac output (CO); and shortened pre-ejection period (PEP). The didactic film had little impact on cardiovascular activity. While an increase in total peripheral resistance (TPR) occurred, the humorous film was largely notable for a reduction in beta-adrenergic drive, as evidenced by reduced CO and a lengthening of PEP. In contrast to previous research reporting a rise in sIgA particular to humorous exposures, the sIgA secretion rate, although enhanced by exposure to the films, did not vary with film content.

Prevalence of Campylobacter spp. in poultry and poultry meat in Germany

Of 509 samples from poultry flocks, 209 isolates (41.1%) were Campylobacter positive. The number of positive cases in broiler carcasses was 45.9%. Of 52 pheasants investigated, 25.9% were Campylobacter positive. Campylobacter jejuni was isolated from 86 (42.0%) poultry flock samples, 47 (43%) broiler samples and 15 (28%) wild pheasant samples. C. coli was found at a rate of 1.2% in poultry flocks, 13% in broilers and 21% in pheasants.

Secretory immunoglobulin A and cardiovascular activity during mental arithmetic and paced breathing

The role of the autonomic nervous system in secretory immunoglobulin A (sIgA) responses to laboratory challenge was explored in a study in which sIgA and cardiovascular activity were recorded at rest and during mental arithmetic and paced breathing. These tasks were selected to preferentially engage the sympathetic and parasympathetic nervous systems, respectively. Mental arithmetic elicited a mixed pattern of increased alpha- and beta-adrenergic activity and a reduction in parasympathetic activity; diastolic blood pressure, total peripheral resistance, and systolic blood pressure increased, preejection period shortened, and heart rate variability decreased. In contrast, paced breathing primarily elicited an increase in parasympathetic activity; heart rate variability increased. Mental arithmetic also provoked an increase in sIgA concentration but no change in saliva volume, whereas paced breathing affected neither sIgA concentration nor saliva volume. These data suggest that sIgA responses to laboratory challenges are mediated by sympathetic rather than parasympathetic processes.

Secretory immunoglobulin A and cardiovascular reactions to mental arithmetic, cold pressor, and exercise: effects of beta-adrenergic blockade

We investigated the influence of sympathetic nervous system processes on mucosal immunity by comparing the effects of beta-adrenoceptor blockade with 40 mg propranolol and placebo on secretory immunoglobulin A (sIgA) at rest and during paced serial arithmetic, cold pressor, and submaximal cycling. These tasks produced patterns of cardiovascular activity indicative of combined alpha- and beta-adrenergic, alpha-adrenergic, and beta-adrenergic activation, respectively. The effectiveness of the beta blockade was confirmed by the attenuation under propranolol of the shortening of the cardiac preejection period and the tachycardia elicited by mental arithmetic and exercise. The cold pressor test did not affect sIgA under either the placebo or the propranolol. Mental arithmetic increased sIgA concentration, and this increase was not blocked by propranolol. Exercise elicited increases in both sIgA concentration and sIgA secretion rate, which were not diminished by beta blockade. These data suggest that sIgA is not regulated by beta-adrenergic mechanisms.