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Supplementary Tables from NID2 and HOXA9 Promoter Hypermethylation as Biomarkers for Prevention and Early Detection in Oral Cavity Squamous Cell Carcinoma Tissues and Saliva

Supplementary Figures from NID2 and HOXA9 Promoter Hypermethylation as Biomarkers for Prevention and Early Detection in Oral Cavity Squamous Cell Carcinoma Tissues and Saliva

The overall aim of this contribution to the 'Second Bill Morgan Memorial Special Issue' is to provide a high-level review of a recent report developed by a Committee for the National Council on Radiation Protection and Measurements (NCRP) titled 'Approaches for Integrating Information from Radiation Biology and Epidemiology to Enhance Low-Dose Health Risk Assessment'. It derives from previous NCRP Reports and Commentaries that provide the case for integrating data from radiation biology studies (available and proposed) with epidemiological studies (also available and proposed) to develop Biologically-Based Dose-Response (BBDR) models. In this review, it is proposed for such models to leverage the adverse outcome pathways (AOP) and key events (KE) approach for better characterizing radiation-induced cancers and circulatory disease (as the example for a noncancer outcome). The review discusses the current state of knowledge of mechanisms of carcinogenesis, with an emphasis on radiation-induced cancers, and a similar discussion for circulatory disease. The types of the various informative BBDR models are presented along with a proposed generalized BBDR model for cancer and a more speculative one for circulatory disease. The way forward is presented in a comprehensive discussion of the research needs to address the goal of enhancing health risk assessment of exposures to low doses of radiation. The use of an AOP/KE approach for developing a mechanistic framework for BBDR models of radiation-induced cancer and circulatory disease is considered to be a viable one based upon current knowledge of the mechanisms of formation of these adverse health outcomes and the available technical capabilities and computational advances. The way forward for enhancing low-dose radiation risk estimates will require there to be a tight integration of epidemiology data and radiation biology information to meet the goals of relevance and sensitivity of the adverse health outcomes required for overall health risk assessment at low doses and dose rates.

The Adverse Outcome Pathway (AOP) framework, a systematic tool that can link available mechanistic data with phenotypic outcomes of relevance to regulatory decision-making, is being explored in areas related to radiation risk assessment. To examine the challenges including the use of AOPs to support the radiation protection community, an international horizon-style exercise was initiated through the Organisation for Economic Co-operation and Development Nuclear Energy Agency High-Level Group on Low Dose Research Radiation/Chemical AOP Joint Topical Group. The objective of the HSE was to facilitate the collection of ideas from a range of experts, to short-list a set of priority research questions that could, if answered, improve the description of the radiation dose-response relationship for low dose/dose-rate exposures, as well as reduce uncertainties in estimating the risk of developing adverse health outcomes following such exposures. The HSE was guided by an international steering committee of radiation risk experts. In the first phase, research questions were solicited on areas that can be supported by the AOP framework, or challenges on the use of AOPs in radiation risk assessment. In the second phase, questions received were refined and sorted by the SC using a best-worst scaling method. During a virtual 3-day workshop, the list of questions was further narrowed. In the third phase, an international survey of the broader radiation protection community led to an orderly ranking of the top questions. Of the 271 questions solicited, 254 were accepted and categorized into 9 themes. These were further refined to the top 25 prioritized questions. Among these, the higher ranked questions will be considered as ‘important’ to drive future initiatives in the low dose radiation protection community. These included questions on the ability of AOPs to delineate responses across different levels of biological organization, and how AOPs could be applied to address research questions on radiation quality, doses or dose-rates, exposure time patterns and deliveries, and uncertainties in low dose/dose-rate effects. A better understanding of these concepts is required to support the use of the AOP framework in radiation risk assessment. Through dissemination of these results and considerations on next steps, the JTG will address select priority questions to advance the development and use of AOPs in the radiation protection community. The major themes observed will be discussed in the context of their relevance to areas of research that support the system of radiation protection.

The recently published NCRP Commentary No. 27 evaluated the new information from epidemiologic studies as to their degree of support for applying the linear nonthreshold (LNT) model of carcinogenic effects for radiation protection purposes (NCRP 2018 Implications of Recent Epidemiologic Studies for the Linear Nonthreshold Model and Radiation Protection, Commentary No. 27 (Bethesda, MD: National Council on Radiation Protection and Measurements)). The aim was to determine whether recent epidemiologic studies of low-LET radiation, particularly those at low doses and/or low dose rates (LD/LDR), broadly support the LNT model of carcinogenic risk or, on the contrary, demonstrate sufficient evidence that the LNT model is inappropriate for the purposes of radiation protection. An updated review was needed because a considerable number of reports of radiation epidemiologic studies based on new or updated data have been published since other major reviews were conducted by national and international scientific committees. The Commentary provides a critical review of the LD/LDR studies that are most directly applicable to current occupational, environmental and medical radiation exposure circumstances. This Memorandum summarises several of the more important LD/LDR studies that incorporate radiation dose responses for solid cancer and leukemia that were reviewed in Commentary No. 27. In addition, an overview is provided of radiation studies of breast and thyroid cancers, and cancer after childhood exposures. Non-cancers are briefly touched upon such as ischemic heart disease, cataracts, and heritable genetic effects. To assess the applicability and utility of the LNT model for radiation protection, the Commentary evaluated 29 epidemiologic studies or groups of studies, primarily of total solid cancer, in terms of strengths and weaknesses in their epidemiologic methods, dosimetry approaches, and statistical modelling, and the degree to which they supported a LNT model for continued use in radiation protection. Recommendations for how to make epidemiologic radiation studies more informative are outlined. The NCRP Committee recognises that the risks from LD/LDR exposures are small and uncertain. The Committee judged that the available epidemiologic data were broadly supportive of the LNT model and that at this time no alternative dose-response relationship appears more pragmatic or prudent for radiation protection purposes.

The US Environmental Protection Agency’s Guidelines for Carcinogen Risk Assessment ( USEPA, 2005a ) uses an analytic framework for conducting a quantitative cancer risk assessment that is based on mode of action (MoA)/key events and human relevance. The approach stresses the enhanced value of utilizing mechanistic data to inform the risk assessment process, in particular for dose–response assessment and risk characterization. A key component of this approach is to distinguish chemicals on the basis of a broad MoA classification, namely, DNA reactivity versus the corollary non-DNA reactivity. This DNA reactivity is a consequence of the parent chemical or a reactive metabolite binding covalently to DNA to produce a DNA adduct or some other DNA structural modification. The metabolism and DNA adduct (or modification) profiles are presented for the major kDNA-reactive chemical or activity classes—polycyclic aromatic hydrocarbons, arylamines and nitro-aryl hydrocarbons, aflatoxins, small alkylators, halogenated hydrocarbons, endogenous lipid peroxidation products, DNA–DNA and DNA–protein cross-linkers, strand breakage, and DNA intercalators. The conversion of DNA adducts or other structural modifications into gene and chromosomal mutations by errors of DNA replication on the damaged template (or occasionally by errors of DNA repair) can lead to cells being initiated along the key event pathway to the development of neoplasms. For the conduct of a quantitative cancer risk assessment, it is necessary to have an understanding of and data on both the chemistry and biological effects of DNA-reactive chemicals. This article provides the links between those two needs.

There is quite an extensive set of epidemiology studies conducted for a range of different radiation exposure scenarios and in some cases at doses that can be considered to be in the low dose range (

This review is a contribution to the memory of Dr William (Bill) Morgan and highlights an area of research and deliberation that he considered extremely important in support of the setting of protective radiation dose limits. Biological research has generally played a minor role in the estimation of adverse health outcomes following exposure to low doses and low dose rates of radiation. The reliance has been on the available, quite extensive data base of epidemiology studies. The major concern is that such studies are for moderate to high doses requiring risk extrapolation methodologies for estimating low dose effects. There are significant uncertainties associated with this approach. This review will discuss how radiation biology studies can potentially reduce this uncertainty through the use of a key events/adverse outcome pathways approach to identify bioindicators of cancer and non-cancer effects for use as parameters in biologically-based dose-response (BBDR) models. Such models would allow for an improved extrapolation approach for estimating health effects at low doses and low dose rates of radiation.Based on reported and ongoing studies for environmental chemicals, the adverse outcome/key events approach is a viable one for enhanced risk assessment (and risk management practice). The identification of informative bioindicators of adverse health effects will be a challenge but with modern molecular and advanced computational techniques, it is certainly feasible. This approach provides a framework for defining a low dose radiation research program; something that was of great importance to Bill Morgan.

Crossbred beef heifers [n = 96; initial shrunk BW=238 kg (SD 21.5)] were used in a completely randomized design to evaluate climatic effects on feedlot heifer growth and efficiency. The study was conducted from November 8, 1991 to May 11, 1992. Heifers were assembled into groups at the Ruminant Nutrition Center (RNC) in Brookings, SD. One group (TX; n = 48) was shipped to New Deal, Texas and fed on slatted-concrete floors, and the second group (SD; n = 48), was shipped half-way to Texas, returned to the RNC, and fed on solid-concrete floors. Transit distance was 1,530 km. Pen was the experimental unit (6 to 8 head·pen-1); diets, health management, and implant programs were normalized across locations. The finishing diet was fed from d 33 to 185 at both locations and the energetics assessment was for the period from d 60 to 185. There were 18 d below -7.8°C and 102 d below 5°C in SD. Transit shrink, estimated empty body fat % (EBF), BW adjusted to 28% EBF (AFBW), and DMI did not differ (P ≥ 0.10). Heifer ADG was 18% greater (P < 0.05) in TX (1.40 vs. 1.16 ± 0.037 kg). Observed vs. predicted dietary energy differed (P ≤ 0.05), for NEm (0.97 vs. 0.87 ± 0.013) and NEg (0.97 vs. 0.84 ± 0.016) for TX and SD, respectively. Using calculated diet energy values based upon TX heifer performance as a reference, relative adjustments to metabolic rate were calculated. The estimated metabolic rate was elevated (P < 0.05) for SD heifers (0.077 vs. 0.101 ± 0.0031 Mcal/MBS). These results indicate that heifers fed in South Dakota had a 31% increase in metabolic rate when compared to heifers fed in the Texas panhandle. More of these types of assessments are needed to improve projection and tracking models used in precision cattle feeding.

A public workshop, organized by a Steering Committee of scientists from government, industry, universities and research organizations, was held at the National Institute of Environmental Health Sciences (NIEHS) in September, 2010. The workshop explored the dose-response implications of toxicant modes of action (MOA) mediated by nuclear receptors. The dominant paradigm in human health risk assessment has been linear extrapolation without a threshold for cancer, and estimation of sub-threshold doses for non-cancer and (in appropriate cases) cancer endpoints. However, recent publications question the application of dose-response modeling approaches with a threshold. The growing body of molecular toxicology information and computational toxicology tools has allowed for exploration of the presence or absence of sub-threshold doses for a number of receptor-mediated MOAs. The workshop explored the development of dose-response approaches for nuclear receptor-mediated liver cancer, within a MOA Human Relevance Framework (HRF). Case studies addressed activation of the AHR, the CAR and the PPARα. This article describes the workshop process, key issues discussed and conclusions. The value of an interactive workshop approach to apply current MOA/HRF frameworks was demonstrated. The results may help direct research on the MOA and dose-response of receptor-based toxicity, since there are commonalities for many receptors in the basic pathways involved for late steps in the MOA, and similar data gaps in early steps. Three additional papers in this series describe the results and conclusions for each case-study receptor regarding its MOA, relevance of the MOA to humans and the resulting dose-response implications.

The process of setting radiation protection standards requires the interaction of a number of international and national organizations that in turn require the input of scientific and regulatory experts. Bill Morgan served in an expert capacity for several of these organizations particularly for the application of radiation biology data to risk assessment. He brought great enthusiasm and dedication to these committee efforts. In fact, he really enjoyed this type of service. The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), for example, provides comprehensive reviews of the input data for radiation risk assessments. In this context, they do not conduct risk assessments. In Europe, a research component of the risk assessment process is provided by the Multidisciplinary European Low Dose Initiative (MELODI). Specific issue areas are identified for which additional research can aid in reducing uncertainty in risk assessments. The International Commission on Radiological Protection (ICRP) uses these types of input data to develop nominal cancer risk estimates as input data for establishing dose limits for the public and workers. A similar regulatory role is provided in the US by the National Council on Radiation Protection and Measurements (NCRP). The NCRP Reports address the underlying principles for setting regulatory dose limits for the US public and workers; these differ to a limited extent from those of ICRP. The implementation of dose limits is conducted by individual countries but with significant guidance by the International Atomic Energy Agency (IAEA) through its Basic Safety Standards. The role of other national and international organizations are discussed in this same framework.

Purpose: This review evaluates the role of dose rate on cell and molecular responses. It focuses on the influence of dose rate on key events in critical pathways in the development of cancer. This approach is similar to that used by the U.S. EPA and others to evaluate risk from chemicals. It provides a mechanistic method to account for the influence of the dose rate from low-LET radiation, especially in the low-dose region on cancer risk assessment. Molecular, cellular, and tissues changes are observed in many key events and change as a function of dose rate. The magnitude and direction of change can be used to help establish an appropriate dose rate effectiveness factor (DREF). Conclusions: Extensive data on key events suggest that exposure to low dose-rates are less effective in producing changes than high dose rates. Most of these data at the molecular and cellular level support a large (2–30) DREF. In addition, some evidence suggests that doses delivered at a low dose rate decrease damage to levels below that observed in the controls. However, there are some data human and mechanistic data that support a dose-rate effectiveness factor of 1. In summary, a review of the available molecular, cellular and tissue data indicates that not only is dose rate an important variable in understanding radiation risk but it also supports the selection of a DREF greater than one as currently recommended by ICRP (2007) and BEIR VII (NRC/NAS 2006).

The interfacial electronic structure of C-60/copper phthalocyanine (CuPc)/molybdenum trioxide (MoO3) thin films grown in situ on indium tin oxide (ITO) substrates has been studied using synchrotron radiation-excited photoelectron spectroscopy in an attempt to understand the influence of oxide interlayers on the performance of small molecule organic photovoltaic devices. The MoO3 layer on ITO is found to significantly increase the work function of the substrate and induces large interface dipoles and band bending at the CuPc/MoO3 interface. The large band bending confirms the formation of an internal potential that assists hole extraction from the CuPc layer to the electrode. The electronic structure of the MoO3 layer on ITO was also examined using various soft X-ray spectroscopies to probe the conductive nature of the MoO3 thin film.

The interface electronic structure of a bilayer heterojunction of C60 and three different phthalocyanines grown on indium tin oxide (ITO) has been studied using synchrotron radiation-excited photoelectron spectroscopy. The energy difference between the highest occupied molecular orbital level of the phthalocyanine (donor) layer and the lowest unoccupied molecular orbital level of the C60 (acceptor) layer (EHOMOD − ELUMOA) was determined. The EHOMOD − ELUMOA of a heterojunction with boron subphthalocyanine chloride (SubPc) was found to be much larger than those of copper phthalocyanine (CuPc) and chloro-aluminum phthalocyanine (ClAlPc). This observation is discussed in terms of the difference of the ionization energy of each donor material. Additionally, we have studied the molecular orientation of the phthalocyanine films on ITO using angle-dependent X-ray absorption spectroscopy. We found that the SubPc films showed significant disorder compared to the CuPc and ClAlPc films and also found that EHOMOD − E...

The existence of thresholds for toxicants is a matter of debate in chemical risk assessment and regulation. Current risk assessment methods are based on the assumption that, in the absence of sufficient data, carcinogenesis does not have a threshold, while noncarcinogenic endpoints are assumed to be thresholded. Advances in our fundamental understanding of the events that underlie toxicity are providing opportunities to address these assumptions about thresholds. A key events dose-response analytic framework was used to evaluate three aspects of toxicity. The first section illustrates how a fundamental understanding of the mode of action for the hepatic toxicity and the hepatocarcinogenicity of chloroform in rodents can replace the assumption of low-dose linearity. The second section describes how advances in our understanding of the molecular aspects of carcinogenesis allow us to consider the critical steps in genotoxic carcinogenesis in a key events framework. The third section deals with the case of endocrine disrupters, where the most significant question regarding thresholds is the possible additivity to an endogenous background of hormonal activity. Each of the examples suggests that current assumptions about thresholds can be refined. Understanding inter-individual variability in the events involved in toxicological effects may enable a true population threshold(s) to be identified.

The applications of systems biology approaches have greatly increased in the past decade largely as a consequence of the human genome project and technological advances in genomics and proteomics. Systems approaches have been used in the medical and pharmaceutical realm for diagnostic purposes and target identification. During this same period, the use of mode of action (MOA) for risk assessment has been increasing and there is a need for quantitative risk assessments on an ever-growing number of environmental chemicals. Genome-wide (i.e., global) measurements provide both a discovery engine for identifying MOA and an information base for subsequent evaluation of MOA when conducting a risk assessment. These genome-wide measurements are not chosen based on the hypothesized MOA and therefore represent an unbiased check of the comprehensiveness of an MOA. In addition, optimal design for MOA studies is critical to provide the time and dose dependent data required for quantitative model building. Finally, identification of biomarkers and bioindicators of disease in humans provides a viable way to extrapolate from disease outcomes measured at high exposure levels to those at low exposure levels and thus provide the opportunity to reduce or perhaps eliminate in vivo animal testing. To realize the full potential of these approaches, larger integrated projects which include all these individual components are necessary.

Toxicoproteomics is the use of proteomic technologies to better understand environmental and genetic factors, toxic mechanisms, and modes of action in response to acute exposure to toxicants and in the long-term development of diseases caused or influenced by these exposures. Use of toxicoproteomic technologies to identify key biochemical pathways, mechanisms, and biomarkers of exposure and toxicity will decrease the uncertainties that are associated with human health risk assessments. This review provides an overview of toxicoproteomics from human health risk assessment perspectives. Key toxicoproteomic technologies such as 2-D gel-based proteomic methods and toxicoproteomic approaches are described, and examples of applications of these technologies and methodologies in the risk assessment context are presented. The discussion includes a focus on challenges and future directions.

Total rainfall over Natal, South Africa is the composite of rainfall from a number of synoptic rainfall-producing systems. This paper identifies eight synoptic types and employs discriminant analysis in order to determine whether the defined synoptic types are statistically distinct. Eighty-one per cent of the total rainfall is shown to be associated with four of the eight synoptic types. The dynamic characteristics of each synoptic type are examined and the seasonal and spatial rainfall patterns of the principal rainfall-producing systems are described.

Douglas Fir (Pseudotsuga taxifolia) timber impregnated with ‘Tanalith’ C (a copper–chrome–arsenic water-borne preservative) has been examined by optical microscopy, polarisation microscopy, X-ray diffraction analysis and electron microscopy including electron diffraction analysis. It has been established that the preservative material is situated within the cell wall. A sub-microscopic deposit of random groups of crystals (presumably basic salts) is distributed irregularly throughout the wall, while a proportion at least of the metallic components of the preservative combine with the cellulose in the cell wall to form a metal-cellulose complex.

The diffusion length of carriers in semiconductors is a significant parameter determining the suitability of a material for device applications. Here we describe a simple new technique to measure diffusion length and apply it to a study of two types of disordered GaN. We find the diffusion length to be of the order of microns in nanocrystalline GaN and hundreds of microns in amorphous GaON. Experimentally the method involves the defocussing of a laser spot between two contacts. The results are supported by numerical modelling of the carrier concentrations in the experiment.

The U.S. Environmental Protection Agency's Guidelines for Carcinogen Risk Assessment encourages the use of mechanistic data in the assessment of human cancer risk at low (environmental) exposure levels. The key events that define a particular mode of action for tumor formation have been concentrated to date more on mutational responses that are broadly the result of induced DNA damage and enhanced cell proliferation. While it is clear that these processes are important in terms of tumor induction, other modes that fall under the umbrella of epigenetic responses are increasingly being considered to play an important role in susceptibility to tumor induction by environmental chemicals and as significant modifiers of tumor responses. Alterations in gene expression, DNA repair, cell cycle control, genome stability and genome reprogramming could be the result of modification of DNA methylation and chromatin remodeling patterns as a consequence of exposure to environmental chemicals. These concepts are described and discussed.

The US Environmental Protection Agency recently released its new guidelines for carcinogen risk assessment together with supplemental guidance for assessing susceptibility from early-life exposure to carcinogens. In particular, these guidelines encourage the use of mechanistic data in support of dose-response characterization at doses below those at which an increase in tumor frequency over background levels might be detected. In this context of the utility of mechanistic data for human cancer risk assessment, the International Life Sciences Institute (ILSI) has developed a human relevance framework (HRF) that can be used to assess the plausibility of a mode of action (MoA) described for animal models operating in humans. The MoA is described as a sequence of key events and processes that result in an adverse outcome. A key event is a measurable precursor step that is in itself a necessary element of the MoA or is a bioindicator for such an element. A number of cellular and molecular perturbations have been identified as key events whereby DNA-reactive chemicals can produce tumors. These include DNA adducts in target tissues, gene mutations and/or chromosomal alterations in target tissues and enhanced cell proliferation in target tissues. This type of data integration approach to quantitative cancer risk assessment can be applied to 1,3-butadiene, for example, using data on biomarkers in exposed Czech workers [1]. For this study, an extensive range of biomarkers of exposure and response was assessed, including: polymorphisms in metabolizing enzymes; urinary concentrations of several metabolites of 1,3-butadiene; hemoglobin adducts; HPRT mutations in T-lymphocytes; chromosomal aberrations by FISH and conventional staining procedures; sister chromatid exchanges. Exposure levels were monitored in a comprehensive fashion. For risk assessment purposes, these data need to be considered in the context of how they inform the MoA for leukemia, the tumor type reported to be increased in synthetic rubber workers exposed to 1,3-butadiene. Also, for the HRF it is necessary to establish key events for a MoA in rodents for the induction of tumors by 1,3-butadiene. There is clearly a species difference in sensitivity to tumor induction, with mice being much more sensitive than rats; key events need to explain this difference. For butadiene, the MoA is DNA-reactivity and subsequent mutagenicity and so following the EPA's cancer guidelines, a linear extrapolation is used from the point of departure (POD), unless additional data support a non-linear extrapolation. For the present case, the human bioindicator data are not informative as far as dose-response characterization is concerned. Mouse chromosome aberration data for in vivo exposures might be used for establishing a POD, with linear extrapolation from this POD. The available cytogenetic data from rodent studies appear to be sufficiently extensive and consistent for this to be a viable approach. This approach of using MoA and key events to establish the human relevance can lead to the development of specific informative bioindicators of response that can be used as surrogates to predict the shape of the tumor dose response curve at low doses. Truly informative predictors of tumor responses should be able to provide estimates of human tumor frequencies at low, environmental exposures to 1,3-butadiene.

Recognition that children are a potentially susceptible subpopulation has led to the development of child-specific sensitivity factors. Establishing reliable sensitivity factors in support of risk assessment of early-life stage exposures can be aided by evaluating studies that enhance our understanding both of the biological basis of disease processes and the potential role of environmental exposures in disease etiology. For these reasons, we evaluated childhood acute lymphocytic leukemia (ALL) studies from the point of view of mechanism and etiology. ALL is the most common form of childhood cancer proposed to result from a prenatal primary event and a postnatal second event. This multi-stage model is supported by the observation that chromosomal translocations/fusion genes (e.g., TEL-AML1) involved in producing ALL are detected at birth (prenatal event), and a postnatal event (e.g., TEL deletion) is required for disease manifestation. It appears that a proportion of ALL cases are the result of environmental exposures, in which case preconceptional, prenatal, and postnatal stages are likely to be critical exposure windows. To this end, we recognized postnatal infection-related risk factors as potential candidates associated with the ALL second event. Additionally, we discuss use of ALL-associated fusion genes and genetic polymorphisms, together or separately, as indicators of ALL susceptibility and increased risk. The possibility of using fusion genes alone as biomarkers of response is also discussed because they can serve as predictors of key events in the development of a mode of action (a sequence of key events, starting with interaction of an agent with a cell, ultimately resulting in cancer formation) for particular environmental exposures. Furthermore, we discuss use of an initiated animal model for ALL, namely transgenic mice with TEL-AML1 expression, for exploring mechanisms by which different classes of environmental exposures could be involved in inducing the postnatal step in ALL formation.

In April 2004, the Health and Environmental Sciences Institute, a branch of the International Life Sciences Institute, with support from the National Institute of Environmental Health Sciences, organized a workshop to discuss the biological significance of DNA adducts. Workshop speakers and attendees included leading international experts from government, academia, and industry in the field of adduct detection and interpretation. The workshop initially examined the relationship between measured adduct levels in the context of exposure and dose. This was followed by a discussion on the complex response of cells to deal with genotoxic insult in complex, interconnected, and interdependent repair pathways. One of the major objectives of the workshop was to address the recurring question about the mechanistic and toxicological relevance of low-concentration measured adducts and the presentations in the session entitled "Can low levels of DNA adducts predict adverse outcomes?" served as catalysts for further discussions on this subject during the course of the workshop. Speakers representing the regulatory community and industry reviewed the value, current practices, and limitations of utilizing DNA adduct data in risk assessment and addressed a number of practical questions pertaining to these issues. While no consensus statement emerged on the biological significance of low levels of DNA adducts, the workshop concluded by identifying the need for more experimental data to address this important question. One of the recommendations stemming from this workshop was the need to develop an interim "decision-logic" or framework to guide the integration of DNA adduct data in the risk assessment process. HESI has recently formed a subcommittee consisting of experts in the field and other key stakeholders to address this recommendation as well as to identify specific research projects that could help advance the understanding of the biological significance of low levels of DNA adducts.

It has been known for decades that mutagenicity plays an important role in the activity of most carcinogens. This mutagenicity can result from direct damage to DNA through a chemical being DNA reactive or from indirect effects, such as through the production of oxygen radicals that then react with DNA. This article presents a set of key events whereby DNA reactivity initiates the process of carcinogenicity that leads to the subsequent mutation induction and enhanced cell proliferation that ultimately results in tumor development. This set of key events for DNA-reactive chemicals was applied to two case studies (aflatoxin B1 and dichloromethane) with the aim of assessing the utility of the Human Relevance Framework (HRF) for this class of chemicals. The conclusions were that the HRF was a viable approach for the use of mechanistic data for DNA-reactive chemicals obtained from both laboratory animals and human cells in vivo and in vitro for predicting human carcinogenicity. In the case of aflatoxin B1, the HRF could be used to predict that carcinogenicity in humans was a likely outcome. In contrast, the HRF predicted that the human carcinogenic potential of dichloromethane was at best less likely than in rodents; this conclusion was supported by the available epidemiological data.

A complete mode of action human relevance analysis--as distinct from mode of action (MOA) analysis alone--depends on robust information on the animal MOA, as well as systematic comparison of the animal data with corresponding information from humans. In November 2003, the International Life Sciences Institute's Risk Science Institute (ILSI RSI) published a 2-year study using animal and human MOA information to generate a four-part Human Relevance Framework (HRF) for systematic and transparent analysis of MOA data and information. Based mainly on non-DNA-reactive carcinogens, the HRF features a "concordance" analysis of MOA information from both animal and human sources, with a focus on determining the appropriate role for each MOA data set in human risk assessment. With MOA information increasingly available for risk assessment purposes, this article illustrates the further applicability of the HRF for reproductive, developmental, neurologic, and renal endpoints, as well as cancer. Based on qualitative and quantitative MOA considerations, the MOA/human relevance analysis also contributes to identifying data needs and issues essential for the dose-response and exposure assessment steps in the overall risk assessment.

High doses of ionizing radiation clearly produce deleterious consequences in humans, including, but not exclusively, cancer induction. At very low radiation doses the situation is much less clear, but the risks of low-dose radiation are of societal importance in relation to issues as varied as screening tests for cancer, the future of nuclear power, occupational radiation exposure, frequent-flyer risks, manned space exploration, and radiological terrorism. We review the difficulties involved in quantifying the risks of low-dose radiation and address two specific questions. First, what is the lowest dose of x- or gamma-radiation for which good evidence exists of increased cancer risks in humans? The epidemiological data suggest that it is approximately 10-50 mSv for an acute exposure and approximately 50-100 mSv for a protracted exposure. Second, what is the most appropriate way to extrapolate such cancer risk estimates to still lower doses? Given that it is supported by experimentally grounded, quantifiable, biophysical arguments, a linear extrapolation of cancer risks from intermediate to very low doses currently appears to be the most appropriate methodology. This linearity assumption is not necessarily the most conservative approach, and it is likely that it will result in an underestimate of some radiation-induced cancer risks and an overestimate of others.

The theme that runs through this 26th Taylor Lecture is the question of how can data on the mechanism of induction of genetic alterations by radiations and chemicals be used to support the development of risk estimates, particularly at low exposure levels. The premise is that chromosomal alterations are involved in the development of tumors and birth defects, and that data generated for genetic alterations can be interpreted in terms of these adverse health outcomes. The general conclusions are that chromosomal alterations can be induced by ionizing radiations by a single energy loss event in a target of the size of a DNA molecule and that aberrations generally result from misrepair or failure to repair the induced lesions (generally assumed to be double-strand breaks). Chromosomal alterations induced by chemicals are produced almost exclusively by replication errors on a damaged DNA template. Thus, cell cycle stage and DNA repair and replication fidelity will be influential on overall sensitivity to aberration induction. These same features are also important in considerations of genetic susceptibility-alterations in cell cycle control or DNA repair or replication fidelity can alter sensitivity. The differences in mechanism of induction of chromosomal aberrations by ionizing radiation and chemicals is most important when considering cells at risk and comparative sensitivities among species and cell types. Models of cancer induction have gradually evolved from initiation, promotion, and progression models to multistep genetic models to the most recent one of six acquired characteristics. This evolution has passed the level of concentration of research from single gene, single cell to multiple genes (pathways), and whole tissues. The latter areas of concentration are ideal for addressing with the new genomics, proteomics, and computational modeling approaches. The attention is still on the role of genetic alterations in cancer and hereditary effects and the mechanism of their formation--it is the approaches to address these that are changing.

Coleman, C. N., Blakely, W. F., Fike, J. R., MacVittie, T. J., Metting, N. F., Mitchell, J. B., Moulder, J. E., Preston, R. J., Seed, T. M., Stone, H. B., Tofilon, P. J. and Wong, R. S. L. Molecular and Cellular Biology of Moderate-Dose (1–10 Gy) Radiation and Potential Mechanisms of Radiation Protection: Report of a Workshop at Bethesda, Maryland, December 17–18, 2001. Radiat. Res. 159, 812–834 (2003). Exposures to doses of radiation of 1–10 Gy, defined in this workshop as moderate-dose radiation, may occur during the course of radiation therapy or as the result of radiation accidents or nuclear/radiological terrorism alone or in conjunction with bioterrorism. The resulting radiation injuries would be due to a series of molecular, cellular, tissue and whole-animal processes. To address the status of research on these issues, a broad-based workshop was convened. The specific recommendations were: (1) Research: Identify the key molecular, cellular and tissue pathways that lead from the initial mol...

Finite element techniques have been used to design a controlled-clearance piston–cylinder pressure balance for operation in liquid media in the 250 MPa range in which the effective area is predictable, insensitive to variations in key geometrical and material parameters, and in which the distortion coefficient is negligible. The property which must be known most accurately is the Poisson's ratio of the piston–cylinder materials. The design is relatively insensitive to changes in Young's modulus. Finite element methods are shown to be a powerful technique for investigating the performance of pressure balances. It is demonstrated that, for the geometry in question, the free deformation mode of operation cannot meet these criteria, owing to its predicted distortion coefficient of 0.7164 ppm MPa−1, compared with 0.0012 ppm MPa−1 for the controlled-clearance design.

In trying to decide what type of scientific paper I could prepare as a tribute to Jim Neel, I thought back over the discussions that we had over some 25 years. Sometimes these discussions were on specific topics such as how to extrapolate from mutation data in mice to those for humans following radiation or chemical exposures. On other occasions, our discussions were of a more philosophical nature, particularly on where the field of epidemiology might or needed to go. For example, what types of data are needed for assessing the public health impact of exposure to environmental agents. Perhaps because I enjoyed these discussions so much, I have chosen to take a look from a current perspective at the field of molecular epidemiology. Jim Neel would have loved to have entered into this discussion; he would have enhanced it in is own inimitable way.

Surfers at Durban, South Africa, reveal a tendency to cluster in a number of different spaces off the bathing beaches. While this activity appears to function in a social environment that is at the same time companionable, competitive or exclusive, the manner in which the usually robust interaction with the material environment contributes to the construction of surfing space is not visibly evident to the outsider. A survey reveals that surfers construct surfing space out of images of a normative wave environment and practices and processes that are both sensory and social. Images of the perfect wave that describe the normative wave environment sought by surfers are acquired from surfing magazines and other media sources. Knowledge of wave shapes, winds and currents is provided by sensory-derived experience gained in the waves. Individual and group attitudes and behaviour in surfing spaces are socially constructed around issues of identity and exclusion. The path of surfing space construction is shown to ...

The HESI RISK21 project formed the Dose-Response/Mode-of-Action Subteam to develop strategies for using all available data (in vitro, in vivo, and in silico) to advance the next-generation of chemical risk assessments. A goal of the Subteam is to enhance the existing Mode of Action/Human Relevance Framework and Key Events/Dose Response Framework (KEDRF) to make the best use of quantitative dose-response and timing information for Key Events (KEs). The resulting Quantitative Key Events/Dose-Response Framework (Q-KEDRF) provides a structured quantitative approach for systematic examination of the dose-response and timing of KEs resulting from a dose of a bioactive agent that causes a potential adverse outcome. Two concepts are described as aids to increasing the understanding of mode of action-Associative Events and Modulating Factors. These concepts are illustrated in two case studies; 1) cholinesterase inhibition by the pesticide chlorpyrifos, which illustrates the necessity of considering quantitative dose-response information when assessing the effect of a Modulating Factor, that is, enzyme polymorphisms in humans, and 2) estrogen-induced uterotrophic responses in rodents, which demonstrate how quantitative dose-response modeling for KE, the understanding of temporal relationships between KEs and a counterfactual examination of hypothesized KEs can determine whether they are Associative Events or true KEs.

We have used VSOP space very long baseline interferometry observations to measure the brightness temperature distribution of a well-defined sub-set of the Pearson-Readhead sample of extragalactic radio sources. VLBI which is restricted to Earth-diameter baselines is not generally sensitive to emitting regions with brightness temperatures greater than approximately $10^{12}$ K, coincidentally close to theoretical estimates of brightness temperature limits, $10^{11} - 10^{12}$ K. We find that a significant proportion of our sample have brightness temperatures greater than $10^{12}$ K; many have unresolved components on the longest baselines, and some remain completely unresolved. These observations begin to bridge the gap between the extended jets seen with ground-based VLBI and the microarcsecond structures inferred from intraday variability, evidenced here by the discovery of a relationship between intraday variability and VSOP-measured brightness temperature, likely due to the effects of relativistic beaming. Also, lower limits on jet Lorentz factors, estimated from space VLBI observations, are starting to challenge numerical simulations that predict low Lorentz factor jets., 4 pages + 1 figure, ApJ letters, accepted

The Rudh’ a Chromain sill is a composite minor intrusion emplaced into Jurassic sandstones on the south coast of the Ross of Mull, NW Scotland, and is part of a suite of basic–silicic sheets associated with the early development of the 58–56 Ma Mull Central Igneous Complex. New whole-rock major and trace element data combined with Sr–Nd–Pb isotope data indicate that two distinct magma end members were involved in the formation of the sill: a tholeiitic basaltic andesite magma generated by contamination and fractional crystallization of regionally available olivine tholeiite basaltic magma, and a rhyolitic magma produced predominantly through crustal melting of basement metasediments. Intermediate compositions at the gradational boundaries between the basic margins and silicic interior of the sill formed by high temperature diffusive hybridization within a compositionally-zoned magma reservoir prior to sheet emplacement. The basic portions of the sheet are replete with a large variety of crustal xenoliths, as well as numerous gabbroic and noritic cumulate fragments. The Rudh’ a’ Chromain sill therefore preserves evidence for the complex interplay between a number of magmatic processes which, when combined with data from the remainder of the suite, suggests that the magmatic plumbing system which fed the sill complex was not simply one large, long-lived magma chamber, but rather a plexus of variably connected sheet-like magma reservoirs.

Few writers have commented on how seaside leisure spaces are socially constructed, who competes for their use, and how they may change. This paper discusses how these spaces have been identified and partitioned at Durban, South Africa, as new tourist populations discover them. Given the history of ethnic separation and contemporary social and political change in this country, attention is focussed on the extent to which groups retain and express a sense of identity in the construction of leisure spaces. Selected spaces are discussed to illustrate how they may be constructed around notions of cultural identity, the possession of particular skills, or access to scarce spatial and material resources.

DNA damage response pathways coordinate the cellular response to DNA damage. To investigate the roles of tumor suppressor genes in these pathways, human lymphoblastoid cells (wild-type, p53−/− , ATM−/− ) were treated for 1 h with 0–3 μg/ml of the radiomimetic compound bleomycin (BLM), and cells treated in G 2 were analyzed for chromatid aberrations. BLM-induced aberration frequencies were significantly increased, to the greatest extent in the ATM−/− cells and, to a lesser extent, in the p53−/− cells compared to wild-type cells. These observations are consistent with p53 and ATM acting in a damage response pathway activated by DNA strand breaks. The consequences of disrupting this pathway were further investigated by studies using wortmannin, a PI-3 kinase and DNA repair inhibitor. Wortmannin significantly increased the BLM-induced aberration frequencies in all but the ATM−/− cells, elevating the sensitivity of p53−/− cells to ATM−/− levels and that of wild-type cells to intermediate levels. These differential sensitivities suggest that the ATM phenotype is the result of dual cellular defects, one involving p53 and the other a wortmannin-sensitive component. Similar studies in Brca1+/− and Brca2+/− human lymphoblasts showed no increased sensitization to BLM in the absence of inhibitor, and differential sensitization by wortmannin. To determine if there was any substrate specificity for p53- and ATM-mediated DNA damage responses, chromatid aberrations were assessed in wild-type, p53−/− , and ATM−/− cells exposed to 0–0.4 μg/ml neocarzinostatin (NCS) for 1 h. In contrast to results with BLM, the p53−/− cells exhibited a low sensitivity to NCS-induced aberrations, similar to wild-type, while ATM−/− cells remained highly sensitive. This suggests that the response to BLM- and NCS-induced lesions involves different mechanisms.

The Cnoc Rhaonastil minor dolerite intrusion on Islay, NW Scotland represents a single body of alkali olivine basalt magma which differentiated in situ, from leucodolerite, through teschenite to minor nepheline syenite. The syenites occur as isolated nests and pegmatitic schlieren within the leucodolerite, and schlieren of gabbroic pegmatite also occur at the margin of the teschenite. The differentiated rocks contain pyroxene, amphibole and biotite of variable compositions which reflect both primary fractionation processes and late-stage deuteric alteration and reaction.Mafic phases within the gabbroic pegmatite, teschenite and syenite are typically rimmed and speckled with biotite, the composition of which is controlled by the local environment of crystallization. The nepheline syenites contain primary ferro-kaersutite which, where in contact with interstitial patches, has been altered to arfvedsonite, which occasionally contains up to 1.2 wt.% ZrO2. The occurrence of Zr-arfvedsonite (and of Zr-aegirine) in interstitial patches suggests that variably trace element-enriched domains existed within the residual melts on very small scales.

As part of the cultural life of the city, restaurants provide sacred spaces in which the pleasures of eating and communicating can be experienced and valued. They also chronicle trends and shifts in cultural tastes, social behaviour and community fears as urban residents respond to the influence of globalization, the experience of cultural interaction, and perceptions of threats to personal safety. The purpose of this paper is to examine these trends in the ‘colonial’ core region of Durban, South Africa. Restaurants were shown to cluster in four districts: the central business district, the beachfront, and two districts in a suburban environment where the residents are predominantly white South Africans. Once the domain of white privilege, the central business district and beachfront are shown to have undergone a transformation towards multiculturalism in recent years. Impelled by images of urban disorder and increasing crime levels associated with this trend, white consumers increasingly have sh...

This study examined the interactive effects of pregnancy and aerobic conditioning on maternal cardiac structure and function. Effects of closely monitored cycle ergometer conditioning were studied during the second (TM2) and third trimesters (TM3) in 22 previously sedentary pregnant women (exercised group, EG) and a nonexercising pregnant control group with similar characteristics (CG, n = 19). Subjects were studied in the resting state by two-dimensional echocardiography and during cycle ergometer exercise at three steady-state power outputs at the start of TM2 (ENTRY), at the end of TM2 and TM3 (postconditioning), and 3-4 months postpartum (NPR, nonpregnant reference, CG only). Aerobic conditioning did not increase left ventricular dimensions beyond those attributable to pregnancy itself. In addition, in contrast with previous studies of nonpregnant women, physical conditioning during pregnancy did not reduce heart rate (HR) in the resting state. During exercise, the slope of the HR versus oxygen uptake (Vo2) regression decreased significantly between preconditioning and the end of TM3 in the EG, suggesting that training-induced reductions in HR become more evident with increasing exercise intensity. Also, significant reductions in oxygen pulse (Vo2/HR) were observed at all three work rates in the CG, but not in the EG. These findings support the hypothesis that the cardiovascular effects of aerobic conditioning are obscured by more powerful effects of pregnancy in the resting state but become "unmasked" during strenuous exercise.Key words: human gestation, cycle ergometer exercise, echocardiography, heart rate, stroke volume.

This paper describes a European comparison of free-field hydrophone calibrations in the frequency range 10 kHz to 315 kHz. A total of twelve participants from seven European countries took part by calibrating three reference hydrophones, with project coordination provided by the National Physical Laboratory (NPL), UK. The agreement between the results was generally encouraging, with a majority of the results lying within 1 dB of the grand mean. However, some large variations were observed, and the uncertainties in the calibrations were typically underestimated by the participants, with the maximum differences from the grand means almost invariably exceeding the quoted overall uncertainties. A discussion is given of possible reasons for the disagreement, and of useful further work identified as a result of this comparison.

A European comparison of 1 mm hydrophone calibrations in the frequency range 0.5 MHz to 15 MHz is summarized. The project, organized by the Bureau Communautaire de Reference (BCR) of the Commission of the European Communities, involved five participants from different countries measuring the free-field sensitivity of three types of miniature ultrasonic hydrophone. Three different absolute calibration methods were used in the project, which was completed and published in 1991. The uncertainties quoted at the 95% confidence level ranged from 2.3% to 18%, depending on the frequency, method and laboratory. Agreement between laboratories was generally within a few parts in 102 in the range 0.5 MHz to 5 MHz but individual results differed by up to 15% from the grand mean at 10 MHz and 15 MHz.

Plagioclase-rich reaction zones occur around numerous aluminous crustal xenoliths within a suite of Palaeogene sub-volcanic basic sheets on the Isle of Mull, NW Scotland. The xenoliths consist of a glassy core, containing mullite needles, generated from the melting of pelitic source rocks. Thick plagioclase mantles grew at the interface between the aluminous liquid and the enclosing basaltic magma and provide a high-level analogue for the petrogenesis of Proterozoic massif-type anorthosites. Similar interactions between mantle-derived basic magmas ponded at the base of the crust and relatively Al-rich lower crustal lithologies would result in the precipitation of large volumes of plagioclase. Anorthosite massifs were then emplaced at higher crustal levels as crystal-rich mushes within relatively juvenile Proterozoic crust. The model negates the need to crystallize large volumes of mafic minerals prior to the production of plagioclase-saturated liquids, and also accounts for the significant influence of crustal sources on the isotopic signatures of all members of the anorthosite suite.