Radiation Adverse Outcome Pathways (AOPs) are on the Horizon: Advancing Radiation Protection through an International Horizon-Style Exercisewe

Purpose: 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 (HSE) 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 (JTG). 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.Materials and methods: The HSE was guided by an international steering committee (SC) 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 (BWS) 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.Results: 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.Conclusion: 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.

Exploring ecosystem-based management in the North Atlantic

The United States, the EU and Canada established a trilateral working group on the ecosystem approach to ocean health and stressors under the Atlantic Ocean Research Alliance. Recognizing the Atlantic Ocean as a shared resource and responsibility, the working group sought to advance understanding of the Atlantic Ocean and its dynamic systems to improve ocean health, enhance ocean stewardship and promote the sustainable use and management of its resources. This included consideration of multiple ocean-use sectors such as fishing, shipping, tourism and offshore energy. The working group met for 4 years and worked through eight steps that covered the development of common language as a basis for collaboration, challenges of stakeholder engagement, review of the governance mandates, exploring the links between sectors and ecosystems effects, identifying gaps in knowledge and uptake of science, identification of tools for ecosystem-based management, customary best practice for tool development and communication of key research priorities. The key findings were that ecosystem-based management enables new benefits and opportunities, and that we need to make the business case. Further findings were that adequate mandates and effective tools exist for ecosystem-based management, and that ecosystem-based management urgently requires integration of human dimensions, so we must diversify the conversation. In addition, it was found that stakeholders do not see their stake in ecosystem-based management, so greater engagement with stakeholders and targeting of ocean literacy is required and a sustainable future requires a sustained investment in ecosystem-based management, so long-term commitment is key.

Toward Sustainable Environmental Quality: Priority Research Questions for Asia

Environmental and human health challenges are pronounced in Asia, an exceptionally diverse and complex region where influences of global megatrends are extensive and numerous stresses to environmental quality exist. Identifying priorities necessary to engage grand challenges can be facilitated through horizon scanning exercises, and to this end we identified and examined 23 priority research questions needed to advance toward more sustainable environmental quality in Asia, as part of the Global Horizon Scanning Project. Advances in environmental toxicology, environmental chemistry, biological monitoring, and risk-assessment methodologies are necessary to address the adverse impacts of environmental stressors on ecosystem services and biodiversity, with Asia being home to numerous biodiversity hotspots. Intersections of the food-energy-water nexus are profound in Asia; innovative and aggressive technologies are necessary to provide clean water, ensure food safety, and stimulate energy efficiency, while improving ecological integrity and addressing legacy and emerging threats to public health and the environment, particularly with increased aquaculture production. Asia is the largest chemical-producing continent globally. Accordingly, sustainable and green chemistry and engineering present decided opportunities to stimulate innovation and realize a number of the United Nations Sustainable Development Goals. Engaging the priority research questions identified herein will require transdisciplinary coordination through existing and nontraditional partnerships within and among countries and sectors. Answering these questions will not be easy but is necessary to achieve more sustainable environmental quality in Asia. Environ Toxicol Chem 2020;39:1485-1505. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Towards Sustainable Environmental Quality: Priority Research Questions for the Australasian Region of Oceania

Environmental challenges persist across the world, including the Australasian region of Oceania, where biodiversity hotspots and unique ecosystems such as the Great Barrier Reef are common. These systems are routinely affected by multiple stressors from anthropogenic activities, and increasingly influenced by global megatrends (e.g., the food-energy-water nexus, demographic transitions to cities) and climate change. Here we report priority research questions from the Global Horizon Scanning Project, which aimed to identify, prioritize, and advance environmental quality research needs from an Australasian perspective, within a global context. We employed a transparent and inclusive process of soliciting key questions from Australasian members of the Society of Environmental Toxicology and Chemistry. Following submission of 78 questions, 20 priority research questions were identified during an expert workshop in Nelson, New Zealand. These research questions covered a range of issues of global relevance, including research needed to more closely integrate ecotoxicology and ecology for the protection of ecosystems, increase flexibility for prioritizing chemical substances currently in commerce, understand the impacts of complex mixtures and multiple stressors, and define environmental quality and ecosystem integrity of temporary waters. Some questions have specific relevance to Australasia, particularly the uncertainties associated with using toxicity data from exotic species to protect unique indigenous species. Several related priority questions deal with the theme of how widely international ecotoxicological data and databases can be applied to regional ecosystems. Other timely questions, which focus on improving predictive chemistry and toxicology tools and techniques, will be important to answer several of the priority questions identified here. Another important question raised was how to protect local cultural and social values and maintain indigenous engagement during problem formulation and identification of ecosystem protection goals. Addressing these questions will be challenging, but doing so promises to advance environmental sustainability in Oceania and globally.

Toward Sustainable Environmental Quality: Priority Research Questions for North America

Anticipating, identifying, and prioritizing strategic needs represent essential activities by research organizations. Decided benefits emerge when these pursuits engage globally important environment and health goals, including the United Nations Sustainable Development Goals. To this end, horizon scanning efforts can facilitate identification of specific research needs to address grand challenges. We report and discuss 40 priority research questions following engagement of scientists and engineers in North America. These timely questions identify the importance of stimulating innovation and developing new methods, tools, and concepts in environmental chemistry and toxicology to improve assessment and management of chemical contaminants and other diverse environmental stressors. Grand challenges to achieving sustainable management of the environment are becoming increasingly complex and structured by global megatrends, which collectively challenge existing sustainable environmental quality efforts. Transdisciplinary, systems-based approaches will be required to define and avoid adverse biological effects across temporal and spatial gradients. Similarly, coordinated research activities among organizations within and among countries are necessary to address the priority research needs reported here. Acquiring answers to these 40 research questions will not be trivial, but doing so promises to advance sustainable environmental quality in the 21st century. Environ Toxicol Chem 2019;38:1606-1624. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Toward sustainable environmental quality: Priority research questions for Europe

The United Nations' Sustainable Development Goals have been established to end poverty, protect the planet, and ensure prosperity for all. Delivery of the Sustainable Development Goals will require a healthy and productive environment. An understanding of the impacts of chemicals which can negatively impact environmental health is therefore essential to the delivery of the Sustainable Development Goals. However, current research on and regulation of chemicals in the environment tend to take a simplistic view and do not account for the complexity of the real world, which inhibits the way we manage chemicals. There is therefore an urgent need for a step change in the way we study and communicate the impacts and control of chemicals in the natural environment. To do this requires the major research questions to be identified so that resources are focused on questions that really matter. We present the findings of a horizon-scanning exercise to identify research priorities of the European environmental science community around chemicals in the environment. Using the key questions approach, we identified 22 questions of priority. These questions covered overarching questions about which chemicals we should be most concerned about and where, impacts of global megatrends, protection goals, and sustainability of chemicals; the development and parameterization of assessment and management frameworks; and mechanisms to maximize the impact of the research. The research questions identified provide a first-step in the path forward for the research, regulatory, and business communities to better assess and manage chemicals in the natural environment. Environ Toxicol Chem 2018;37:2281-2295. © 2018 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Climate research priorities for policy-makers, practitioners, and scientists in Georgia, USA

Climate change has far-reaching effects on human and ecological systems, requiring collaboration across sectors and disciplines to determine effective responses. To inform regional responses to climate change, decision-makers need credible and relevant information representing a wide swath of knowledge and perspectives. The southeastern U. S. State of Georgia is a valuable focal area for study because it contains multiple ecological zones that vary greatly in land use and economic activities, and it is vulnerable to diverse climate change impacts. We identified 40 important research questions that, if answered, could lay the groundwork for effective, science-based climate action in Georgia. Top research priorities were identified through a broad solicitation of candidate research questions (180 were received). A group of experts across sectors and disciplines gathered for a workshop to categorize, prioritize, and filter the candidate questions, identify missing topics, and rewrite questions. Participants then collectively chose the 40 most important questions. This cross-sectoral effort ensured the inclusion of a diversity of topics and questions (e.g., coastal hazards, agricultural production, ecosystem functioning, urban infrastructure, and human health) likely to be important to Georgia policy-makers, practitioners, and scientists. Several cross-cutting themes emerged, including the need for long-term data collection and consideration of at-risk Georgia citizens and communities. Workshop participants defined effective responses as those that take economic cost, environmental impacts, and social justice into consideration. Our research highlights the importance of collaborators across disciplines and sectors, and discussing challenges and opportunities that will require transdisciplinary solutions.

Toward sustainable environmental quality: Identifying priority research questions for Latin America

The Global Horizon Scanning Project (GHSP) is an innovative initiative that aims to identify important global environmental quality research needs. Here we report 20 key research questions from Latin America (LA). Members of the Society of Environmental Toxicology and Chemistry (SETAC) LA and other scientists from LA were asked to submit research questions that would represent priority needs to address in the region. One hundred questions were received, then partitioned among categories, examined, and some rearranged during a workshop in Buenos Aires, Argentina. Twenty priority research questions were subsequently identified. These research questions included developing, improving, and harmonizing across LA countries methods for 1) identifying contaminants and degradation products in complex matrices (including biota); 2) advancing prediction of contaminant risks and effects in ecosystems, addressing lab-to-field extrapolation challenges, and understanding complexities of multiple stressors (including chemicals and climate change); and 3) improving management and regulatory tools toward achieving sustainable development. Whereas environmental contaminants frequently identified in these key questions were pesticides, pharmaceuticals, endocrine disruptors or modulators, plastics, and nanomaterials, commonly identified environmental challenges were related to agriculture, urban effluents, solid wastes, pulp and paper mills, and natural extraction activities. Several interesting research topics included assessing and preventing pollution impacts on conservation protected areas, integrating environment and health assessments, and developing strategies for identification, substitution, and design of less hazardous chemicals (e.g., green chemistry). Finally, a recurrent research need included developing an understanding of differential sensitivity of regional species and ecosystems to environmental contaminants and other stressors. Addressing these critical questions will support development of long-term strategic research efforts to advance more sustainable environmental quality and protect public health and the environment in LA. Integr Environ Assess Manag 2018;14:344-357. © 2018 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

U.S. News Media Coverage of Pharmaceutical Pollution in the Aquatic Environment: A Content Analysis of the Problems and Solutions Presented by Actors

Pharmaceutical pollution in the aquatic environment is an issue of concern that has attracted attention by the news media. Understanding the factors that contribute to media framing of pharmaceutical pollution may lead to a better understanding of the management and governance of this issue, including why these pollutants are generally unregulated at this time. This study conducted a content analysis of 405 newspaper articles (81 had substantive information on the topic) from 2007 to 2014, using the search terms "water" and "pharmaceuticals" in the Chicago Tribune, Denver Post, Los Angeles Times, New York Daily News, New York Times, USA Today, Wall Street Journal, and Washington Post. We sought to analyze the factors that contributed to the news media presentation of pharmaceutical pollution in the United States, including the presentation of the risks/safety and solutions by various actors. We found that the primary issues in the news media were uncertainty regarding public health and harm to the environment. The primary solutions recommended within the news media were implementing additional water treatment technologies, taking unused pharmaceuticals to predetermined sites for disposal (take-back programs), and trash disposal of unused pharmaceuticals. Water utilities and scientists presented improved water treatment technology, government actors presented take-back programs, and pharmaceutical representatives, while sparsely involved in the news media, presented trash disposal as their primary solutions. To advance the understanding of the management of pharmaceutical pollution, this article offers further insight into the debate and potential solutions within the news media presentation of this complex scientific topic.

Advancing the adverse outcome pathway framework-An international horizon scanning approach

Our ability to conduct whole-organism toxicity tests to understand chemical safety has been outpaced by the synthesis of new chemicals for a wide variety of commercial applications. As a result, scientists and risk assessors are turning to mechanistically based studies to increase efficiencies in chemical risk assessment and making greater use of in vitro and in silico methods to evaluate potential environmental and human health hazards. In this context, the adverse outcome pathway (AOP) framework has gained traction in regulatory science because it offers an efficient and effective means for capturing available knowledge describing the linkage between mechanistic data and the apical toxicity end points required for regulatory assessments. A number of international activities have focused on AOP development and various applications to regulatory decision-making. These initiatives have prompted dialogue between research scientists and regulatory communities to consider how best to use the AOP framework. Although expert-facilitated discussions and AOP development have been critical in moving the science of AOPs forward, it was recognized that a survey of the broader scientific and regulatory communities would aid in identifying current limitations while guiding future initiatives for the AOP framework. To that end, a global horizon scanning exercise was conducted to solicit questions concerning the challenges or limitations that must be addressed to realize the full potential of the AOP framework in research and regulatory decision-making. The questions received fell into several broad topical areas: AOP networks, quantitative AOPs, collaboration on and communication of AOP knowledge, AOP discovery and development, chemical and cross-species extrapolation, exposure/toxicokinetics considerations, and AOP applications. Expert ranking was then used to prioritize questions for each category, where 4 broad themes emerged that could help inform and guide future AOP research and regulatory initiatives. In addition, frequently asked questions were identified and addressed by experts in the field. Answers to frequently asked questions will aid in addressing common misperceptions and will allow for clarification of AOP topics. The need for this type of clarification was highlighted with surprising frequency by our question submitters, indicating that improvements are needed in communicating the AOP framework among the scientific and regulatory communities. Overall, horizon scanning engaged the global scientific community to help identify key questions surrounding the AOP framework and guide the direction of future initiatives. Environ Toxicol Chem 2017;36:1411-1421. © 2017 SETAC.

Ocean Research Priorities: Similarities and Differences among Scientists, Policymakers, and Fishermen in the United States

Understanding and solving complex ocean conservation problems requires cooperation not just among scientific disciplines but also across sectors. A recently published survey that probed research priorities of marine scientists, when provided to ocean stakeholders, revealed some agreement on priorities but also illuminated key differences. Ocean acidification, cumulative impacts, bycatch effects, and restoration effectiveness were in the top 10 priorities for scientists and stakeholder groups. Significant priority differences were that scientists favored research questions about ocean acidification and marine protected areas; policymakers prioritized questions about habitat restoration, bycatch, and precaution; and fisheries sector resource users called for the inclusion of local ecological knowledge in policymaking. These results quantitatively demonstrate how different stakeholder groups approach ocean issues and highlight the need to incorporate other types of knowledge in the codesign of solutions-oriented research, which may facilitate cross-sectoral collaboration.

Crossing Science-Policy-Societal Boundaries to Reduce Scientific and Institutional Uncertainty in Small-Scale Fisheries

The governance of small-scale fisheries (SSF) is challenging due to the uncertainty, complexity, and interconnectedness of social, political, ecological, and economical processes. Conventional SSF management has focused on a centralized and top-down approach. A major criticism of conventional management is the over-reliance on 'expert science' to guide decision-making and poor consideration of fishers' contextually rich knowledge. That is thought to exacerbate the already low governance potential of SSF. Integrating scientific knowledge with fishers' knowledge is increasingly popular and is often assumed to help reduce levels of biophysical and institutional uncertainties. Many projects aimed at encouraging knowledge integration have, however, been unsuccessful. Our objective in this research was to assess factors that influence knowledge integration and the uptake of integrated knowledge into policy-making. We report results from 54 semi-structured interviews with SSF researchers and practitioners from around the globe. Our analysis is framed in terms of scientific credibility, societal legitimacy, and policy saliency, and we discuss cases that have been partially or fully successful in reducing uncertainty via push-and-pull-oriented boundary crossing initiatives. Our findings suggest that two important factors affect the science-policy-societal boundary: a lack of consensus among stakeholders about what constitutes credible knowledge and institutional uncertainty resulting from shifting policies and leadership change. A lack of training for scientific leaders and an apparent 'shelf-life' for community organizations highlight the importance of ongoing institutional support for knowledge integration projects. Institutional support may be enhanced through such investments, such as capacity building and specialized platforms for knowledge integration.

Behavior, preferences, and willingness to pay for measures aimed at preventing pollution by pharmaceuticals and personal care products in China

The release of pharmaceuticals and personal care products (PPCPs) into the environment has been held up as a potential threat to ecosystem and human health. Using a custom-designed survey of residents living in Xiamen, China, this paper examines individuals' disposal practices, awareness of the environmental impact of PPCPs, and willingness to pay for measures aimed at reducing the likelihood of PPCPs being released into the environment. The vast majority of respondents report that they dispose of PPCPs through the thrash. The results of a contingent valuation experiment suggest a substantial willingness to pay (WTP) for policy measures aimed at reducing PPCP pollution. Income as well as subjective perceptions relating to overall financial health, expenditure on PPCPs, and overall concern with environmental issues emerged as significant predictors of respondents' WTP. Our results should be of interest to policymakers looking for ways to mitigate the introduction of PPCPs in the environment. Integr Environ Assess Manag 2016;12:793-800. © 2015 SETAC.

Non-use Economic Values for Little-Known Aquatic Species at Risk: Comparing Choice Experiment Results from Surveys Focused on Species, Guilds, and Ecosystems

Accounting for non-market economic values of biological diversity is important to fully assess the benefits of environmental policies and regulations. This study used three choice experiments (species-, guild-, and ecosystem-based surveys) in parallel to quantify non-use values for little-known aquatic species at risk in southern Ontario. Mean willingness-to-pay (WTP) ranged from $9.45 to $21.41 per listing status increment under Canada's Species at Risk Act for both named and unnamed little-known species. Given the broad range of valuable ecosystem services likely to accrue to residents from substantial increases in water quality and the rehabilitation of coastal wetlands, the difference in WTP between species- and ecosystem-based surveys seemed implausibly small. It appeared that naming species-the 'iconization' of species in two of the three surveys-had an important effect on WTP. The results suggest that reasonable annual household-level WTP values for little-known aquatic species may be $10 to $25 per species or $10 to $20 per listing status increment. The results highlighted the utility of using parallel surveys to triangulate on non-use economic values for little-known species at risk.

Pathways from marine protected area design and management to ecological success

Using an international dataset compiled from 121 sites in 87 marine protected areas (MPAs) globally (Edgar et al., 2014), I assessed how various configurations of design and management conditions affected MPA ecological performance, measured in terms of fish species richness and biomass. The set-theoretic approach used Boolean algebra to identify pathways that combined up to five ‘NEOLI’ (No-take, Enforced, Old, Large, Isolated) conditions and that were sufficient for achieving positive, and negative, ecological outcomes. Ecological isolation was overwhelming the most important condition affecting ecological outcomes but Old and Large were also conditions important for achieving high levels of biomass among large fishes (jacks, groupers, sharks). Solution coverage was uniformly low (<0.35) for all models of positive ecological performance suggesting the presence of numerous other conditions and pathways to ecological success that did not involve the NEOLI conditions. Solution coverage was higher (>0.50) for negative results (i.e., the absence of high biomass) among the large commercially-exploited fishes, implying asymmetries in how MPAs may rebuild populations on the one hand and, on the other, protect against further decline. The results revealed complex interactions involving MPA design, implementation, and management conditions that affect MPA ecological performance. In general terms, the presence of no-take regulations and effective enforcement were insufficient to ensure MPA effectiveness on their own. Given the central role of ecological isolation in securing ecological benefits from MPAs, site selection in the design phase appears critical for success.

A narrative policy approach to environmental conservation

Due to the urgency and seriousness of the loss of biological diversity, scientists from across a range of disciplines are urged to increase the salience and use of their research by policy-makers. Increased policy nuance is needed to address the science-policy gap and overcome divergent views of separate research and policy worlds, a view still relatively common among conservation scientists. Research impact considerations should recognize that policy uptake is dependent on contextual variables operating in the policy sphere. We provide a novel adaptation of existing policy approaches to evidence impact that accounts for non-evidentiary "societal" influences on decision-making. We highlight recent analytical tools from political science that account for the use of evidence by policy-makers. Using the United Kingdom's recent embrace of the ecosystem approach to environmental management, we advocate analyzing evidence research impact through a narrative lens that accounts for the credibility, legitimacy, and relevance of science for policy.

International scientists' priorities for research on pharmaceutical and personal care products in the environment

Pharmaceuticals and personal care products (PPCPs) are widely discharged into the environment via diverse pathways. The effects of PPCPs in the environment have potentially important human and ecosystem health implications, so credible, salient, and legitimate scientific evidence is needed to inform regulatory and policy responses that address potential risks. A recent "big questions" exercise with participants largely from North America identified 22 important research questions around the risks of PPCP in the environment that would help address the most pressing knowledge gaps over the next decade. To expand that analysis, we developed a survey that was completed by 535 environmental scientists from 57 countries, of whom 49% identified environmental or analytical chemistry as their primary disciplinary background. They ranked the 22 original research questions and submitted 171 additional candidate research questions they felt were also of high priority. Of the original questions, the 3 perceived to be of highest importance related to: 1) the effects of long-term exposure to low concentrations of PPCP mixtures on nontarget organisms, 2) effluent treatment methods that can reduce the effects of PPCPs in the environment while not increasing the toxicity of whole effluents, and 3) the assessment of the environmental risks of metabolites and environmental transformation products of PPCPs. A question regarding the role of cultural perspectives in PPCP risk assessment was ranked as the lowest priority. There were significant differences in research orientation between scientists who completed English and Chinese language versions of the survey. We found that the Chinese respondents were strongly orientated to issues of managing risk profiles, effluent treatment, residue bioavailability, and regional assessment. Among English language respondents, further differences in research orientation were associated with respondents' level of consistency when ranking the survey's 15 comparisons. There was increasing emphasis on the role of various other stressors relative to PPCPs and on risk prioritization as internal decision making consistency increased. Respondents' consistency in their ranking choices was significantly and positively correlated with SETAC membership, authors' number of publications, and longer survey completion times. Our research highlighted international scientists' research priorities and should help inform decisions about the type of hazard and risk-based research needed to best inform decisions regarding PPCPs in the environment. Disciplinary training of a scientist or engineer appears to strongly influence preferences for research priorities to understand PPCPs in the environment. Selection of participants and the depth and breadth of research prioritization efforts thus have potential effects on the outcomes of research prioritization exercises. Further elucidation of how patterns of research priority vary between academic and government scientists and between scientists and other government and stakeholders would be useful in the future and provide information that helps focus scientific effort on socially relevant challenges relating to PPCPs in the environment. It also suggests the potential for future collaborative research between industry, government, and academia on environmental contaminants beyond PPCPs.

Recreational anglers' attitudes, beliefs, and behaviors related to catch-and-release practices of Pacific salmon in British Columbia

The fate of captured and released fish in recreational fisheries depends in large part on fisher handling and behavior. As such, there is a need for promoting adoption of responsible fishing practices. We interviewed recreational sockeye salmon anglers in the lower Fraser River, British Columbia, to assess their awareness of responsible fishing practices and identify gaps where improved education could promote conservation-oriented behaviors. Based on our interview data, we developed three latent class models of salmon angler typologies based on: 1) anglers' fishing behaviors and preferences, 2) anglers' perceived risks to salmon survival due to post-capture live release, and 3) anglers' level of support for education programs. In the first model, we identified salmon-only anglers (33% of sample), lake-species specialists (46%), and all-around anglers (21%). These classes were differentiated primarily by non-salmon fishing activities (e.g., other target species). In the second model, we found four classes of anglers who differed with regards to key factors they thought affected post-release survival: air exposure (39% of sample); water temperature (24%); hook location (22%); and revival effort (15%). In the third model, we found anglers were either supporters (73%) or non-supporters (27%) of angler education programs. Heterogeneity existed among anglers but we found no correlations in angler classes across models, nor any significant demographic or experiential predictors of class membership. Respondents generally had high awareness and application of catch-and-release best practices, with lake-species specialists rating a higher awareness and usage of recommended catch-and-release technique, and were significantly more likely to cut the line on deeply hooked fish than other groups. Our findings provide resource managers with important insight into the attitudes and behaviors of sockeye salmon anglers in the important lower Fraser River recreational fishery. Our findings also highlight, however, the need for further research on the determinants of angler beliefs and behavior in order to customize programs to build anglers' awareness and adoption of responsible fishing practices.

Pharmaceuticals and personal care products in the environment: what are the big questions?

BACKGROUND

Over the past 10-15 years, a substantial amount of work has been done by the scientific, regulatory, and business communities to elucidate the effects and risks of pharmaceuticals and personal care products (PPCPs) in the environment.

OBJECTIVE

This review was undertaken to identify key outstanding issues regarding the effects of PPCPs on human and ecological health in order to ensure that future resources will be focused on the most important areas.

DATA SOURCES

To better understand and manage the risks of PPCPs in the environment, we used the "key question" approach to identify the principle issues that need to be addressed. Initially, questions were solicited from academic, government, and business communities around the world. A list of 101 questions was then discussed at an international expert workshop, and a top-20 list was developed. Following the workshop, workshop attendees ranked the 20 questions by importance.

DATA SYNTHESIS

The top 20 priority questions fell into seven categories: a) prioritization of substances for assessment, b) pathways of exposure, c) bioavailability and uptake, d) effects characterization, e) risk and relative risk, f ) antibiotic resistance, and g) risk management.

CONCLUSIONS

A large body of information is now available on PPCPs in the environment. This exercise prioritized the most critical questions to aid in development of future research programs on the topic.

Scientists' opinions on the global status and management of biological diversity

The large investments needed if loss of biological diversity is to be stemmed will likely lead to increased public and political scrutiny of conservation strategies and the science underlying them. It is therefore crucial to understand the degree of consensus or divergence among scientists on core scientific perceptions and strategies most likely to achieve given objectives. I developed an internet survey designed to elucidate the opinions of conservation scientists. Conservation scientists (n =583) were unanimous (99.5%) in their view that a serious loss of biological diversity is likely, very likely, or virtually certain. Scientists' agreement that serious loss is very likely or virtually certain ranged from 72.8% for Western Europe to 90.9% for Southeast Asia. Tropical coral ecosystems were perceived as the most seriously affected by loss of biological diversity; 88.0% of respondents familiar with that ecosystem type agreed that a serious loss is very likely or virtually certain. With regard to conservation strategies, scientists most often viewed understanding how people and nature interact in certain contexts and the role of biological diversity in maintaining ecosystem function as their priorities. Protection of biological diversity for its cultural and spiritual values and because of its usefulness to humans were low priorities, which suggests that many scientists do not fully support the utilitarian concept of ecosystem services. Many scientists expressed a willingness to consider conservation triage, engage in active conservation interventions, and consider reframing conservation goals and measures of success for conservation of biological diversity in an era of climate change. Although some heterogeneity of opinion is evident, results of the survey show a clear consensus within the scientific community on core issues of the extent and geographic scope of loss of biological diversity and on elements that may contribute to successful conservation strategies in the future.

How research-prioritization exercises affect conservation policy

Conservation scientists are concerned about the apparent lack of impact their research is having on policy. By better aligning research with policy needs, conservation science might become more relevant to policy and increase its real-world salience in the conservation of biological diversity. Consequently, some conservation scientists have embarked on a variety of exercises to identify research questions that, if answered, would provide the evidence base with which to develop and implement effective conservation policies. I synthesized two existing approaches to conceptualizing research impacts. One widely used approach classifies the impacts of research as conceptual, instrumental, and symbolic. Conceptual impacts occur when policy makers are sensitized to new issues and change their beliefs or thinking. Instrumental impacts arise when scientific research has a direct effect on policy decisions. The use of scientific research results to support established policy positions are symbolic impacts. The second approach classifies research issues according to whether scientific knowledge is developed fully and whether the policy issue has been articulated clearly. I believe exercises to identify important research questions have objectives of increasing the clarity of policy issues while strengthening science-policy interactions. This may facilitate the transmission of scientific knowledge to policy makers and, potentially, accelerate the development and implementation of effective conservation policy. Other, similar types of exercises might also be useful. For example, identification of visionary science questions independent of current policy needs, prioritization of best practices for transferring scientific knowledge to policy makers, and identification of questions about human values and their role in political processes could all help advance real-world conservation science. It is crucial for conservation scientists to understand the wide variety of ways in which their research can affect policy and be improved systematically.

Generation of priority research questions to inform conservation policy and management at a national level

Integrating knowledge from across the natural and social sciences is necessary to effectively address societal tradeoffs between human use of biological diversity and its preservation. Collaborative processes can change the ways decision makers think about scientific evidence, enhance levels of mutual trust and credibility, and advance the conservation policy discourse. Canada has responsibility for a large fraction of some major ecosystems, such as boreal forests, Arctic tundra, wetlands, and temperate and Arctic oceans. Stressors to biological diversity within these ecosystems arise from activities of the country's resource-based economy, as well as external drivers of environmental change. Effective management is complicated by incongruence between ecological and political boundaries and conflicting perspectives on social and economic goals. Many knowledge gaps about stressors and their management might be reduced through targeted, timely research. We identify 40 questions that, if addressed or answered, would advance research that has a high probability of supporting development of effective policies and management strategies for species, ecosystems, and ecological processes in Canada. A total of 396 candidate questions drawn from natural and social science disciplines were contributed by individuals with diverse organizational affiliations. These were collaboratively winnowed to 40 by our team of collaborators. The questions emphasize understanding ecosystems, the effects and mitigation of climate change, coordinating governance and management efforts across multiple jurisdictions, and examining relations between conservation policy and the social and economic well-being of Aboriginal peoples. The questions we identified provide potential links between evidence from the conservation sciences and formulation of policies for conservation and resource management. Our collaborative process of communication and engagement between scientists and decision makers for generating and prioritizing research questions at a national level could be a model for similar efforts beyond Canada.

Is there a need for a '100 questions exercise' to enhance fisheries and aquatic conservation, policy, management and research? Lessons from a global 100 questions exercise on conservation of biodiversity

Recent global and regional exercises have been undertaken to identify 100 questions of relevance to policy makers that, if answered, would improve decision making and conservation actions. These were intentionally broad, but all included themes and questions of relevance to aquatic and fisheries professionals (e.g. exploitation, habitat alteration, effectiveness of protected areas, migratory connectivity and environmental effects of aquaculture). Here, the content of the global 100 question exercise relevant to aquatic and fisheries issues is summarized and a critical analysis is provided. Many of the questions addressed in apparently unrelated themes and topics (e.g. terrestrial, agriculture and energy policy) have potential relevance to fisheries and aquatic habitats, which underlines the connectivity between terrestrial and aquatic realms. Given the intimate link between aquatic environmental problems and human activities (including culture and economics), greater understanding of the human dimension is required to inform decision making. Stakeholder perspectives need to be included as a core component of the fisheries management triangle (i.e. managing fish, habitat and people). The benefits and risks of conducting a global 100 questions exercise with an exclusive focus on questions of relevance to fisheries and aquatic practitioners are also considered. There is no question that evidence-based approaches to conservation are essential for addressing the many threats that face aquatic ecosystems and reverse the imperilment trends among ichthyofauna. It is still unclear, however, as to the extent to which 100 questions exercises will help to achieve conservation and management targets for aquatic resources. A global 100 questions exercise that focused on fisheries and aquatic issues would certainly help to generate interest and awareness sufficient to justify such an exercise.

Oxidative stress and renal dysfunction in salt-sensitive hypertension

Hypertension is a risk factor for the development of end-stage renal disease. The mechanisms underlying hypertensive nephropathy are poorly understood. There is evidence, however, that in hypertension there is an accumulation of partially reduced oxygen and its derivatives, known collectively as reactive oxygen species, which may contribute to progressive renal dysfunction. In the present study, we assess the contribution of oxidative stress in the development of salt-dependent hypertensive nephrosclerosis. Going beyond previous end point studies, which inferred renal function either indirectly or only qualitatively, we have determined oxidative stress concurrently with direct and quantitative measurements of renal function (via inulin and p-aminohippuric acid clearances). Moreover, in this time-dependent study, the measurements have been taken under low- as well as high-salt diets. As was expected from previous studies, in the Dahl salt-sensitive rat, a high-salt diet (8% NaCl) resulted in the development of hypertension, in a decreased glomerular filtration rate, and in a decreased renal plasma flow as compared with the normotensive control, the Dahl salt-resistant rat. In addition, however, we found clear evidence for the accumulation of reactive oxygen species in renal tissue homogenates of Dahl salt-sensitive rats on the high-salt diet. Our time-dependent protocol also indicated that renal oxidative stress follows, in time, the development of hypertension. We also found that after 2 weeks of increased salt loading, Dahl salt-sensitive rats excreted less cyclic guanosine monophosphate and NO(x) than Dahl salt-resistant rats on the same diet. It is known that urinary cyclic guanosine monophosphate and NO(x) represent the activity and stable derivatives of renal NO., respectively, and that they closely correlate with renal vascular resistance. Therefore, our results suggest that, in the Dahl salt-sensitive rat, increased oxidative stress is associated with salt-dependent hypertensive nephrosclerosis and that decreased NO. bioavailability may represent a common factor responsible for the vascular and glomerular dysfunction.

Endothelial dysfunction in a murine model of mild hyperhomocyst(e)inemia

Homocysteine is a risk factor for the development of atherosclerosis and its thrombotic complications. We have employed an animal model to explore the hypothesis that an increase in reactive oxygen species and a subsequent loss of nitric oxide bioactivity contribute to endothelial dysfunction in mild hyperhomocysteinemia. We examined endothelial function and in vivo oxidant burden in mice heterozygous for a deletion in the cystathionine beta-synthase (CBS) gene, by studying isolated, precontracted aortic rings and mesenteric arterioles in situ. CBS(-/+) mice demonstrated impaired acetylcholine-induced aortic relaxation and a paradoxical vasoconstriction of mesenteric microvessels in response to superfusion of methacholine and bradykinin. Cyclic GMP accumulation following acetylcholine treatment was also impaired in isolated aortic segments from CBS(-/+) mice, but aortic relaxation and mesenteric arteriolar dilation in response to sodium nitroprusside were similar to wild-type. Plasma levels of 8-epi-PGF(2alpha) (8-IP) were somewhat increased in CBS(-/+) mice, but liver levels of 8-IP and phospholipid hydroperoxides, another marker of oxidative stress, were normal. Aortic tissue from CBS(-/+) mice also demonstrated greater superoxide production and greater immunostaining for 3-nitrotyrosine, particularly on the endothelial surface. Importantly, endothelial dysfunction appears early in CBS(-/+) mice in the absence of structural arterial abnormalities. Hence, mild hyperhomocysteinemia due to reduced CBS expression impairs endothelium-dependent vasodilation, likely due to impaired nitric oxide bioactivity, and increased oxidative stress apparently contributes to inactivating nitric oxide in chronic, mild hyperhomocysteinemia.

Salt-induced hypertension in Dahl salt-resistant and salt-sensitive rats with NOS II inhibition

Although recent evidence suggests that reduced nitric oxide (NO) production may be involved in salt-induced hypertension, the specific NO synthase (NOS) responsible for the conveyance of salt sensitivity remains unknown. To determine the role of inducible NOS (NOS II) in salt-induced hypertension, we treated Dahl salt-resistant (DR) rats with the selective NOS II inhibitor 2-amino-5,6-dihydro-6-methyl-4H-1,3-thiazine (AMT) for 12 days. Tail-cuff systolic blood pressures rose 29 +/- 6 and 42 +/- 8 mmHg in DR rats given 150 and 300 nmol AMT/h, respectively (P < 0.01, 2-way ANOVA) after 7 days of 8% NaCl diet. We observed similar results with two other potent selective NOS II inhibitors, S-ethylisourea (EIT) and N-[3-(aminomethyl)benzyl]acetamidine hydrochloride (1400W). Additionally, AMT effects were independent of alterations in endothelial function as assessed by diameter change of mesenteric arterioles in response to methacholine using videomicroscopy. We, therefore, conclude from these data that NOS II is important in salt-induced hypertension.

Cell-surface protein disulfide isomerase catalyzes transnitrosation and regulates intracellular transfer of nitric oxide

Since thiols can undergo nitrosation and the cell membrane is rich in thiol-containing proteins, we considered the possibility that membrane surface thiols may regulate cellular entry of NO. Recently, protein disulfide isomerase (PDI), a protein that catalyzes thio-disulfide exchange reactions, has been found on the cell-surface membrane. We hypothesized that cell-surface PDI reacts with NO, catalyzes S-nitrosation reactions, and facilitates NO transfer from the extracellular to intracellular compartment. We observed that PDI catalyzes the S-nitrosothiol-dependent oxidation of the heme group of myoglobin (15-fold increase in the rate of oxidation compared with control), and that NO reduces the activity of PDI by 73.1 +/- 21.8% (P < 0.005). To assess the role of PDI in the cellular action of NO, we inhibited human erythroleukemia (HEL) cell-surface PDI expression using an antisense phosphorothioate oligodeoxynucleotide directed against PDI mRNA. This oligodeoxynucleotide decreased cell-surface PDI content by 74.1 +/- 9.3% and PDI folding activity by 46.6 +/- 3.5% compared with untreated or "scrambled" phosphorothioate oligodeoxynucleotide-treated cells (P < 0.0001). This decrease in cell-surface PDI was associated with a significant decrease in cyclic guanosine monophosphate (cGMP) generation after S-nitrosothiol exposure (65.4 +/- 26.7% reduction compared with control; P < 0.05), with no effect on cyclic adenosine monophosphate (cAMP) generation after prostaglandin E1 exposure. These data demonstrate that the cellular entry of NO involves a transnitrosation mechanism catalyzed by cell-surface PDI. These observations suggest a unique mechanism by which extracellular NO gains access to the intracellular environment.

S-Transnitrosation reactions are involved in the metabolic fate and biological actions of nitric oxide

S-Nitrosothiols are a group of potent, bioactive compounds that form through the reaction of nitric oxide (NO) with thiols in the presence of oxygen. These compounds are naturally occurring in vivo, stabilize NO and potentiate its biological effects. S-Nitrosoglutathione is the most abundant intracellular S-nitrosothiol, and the kinetics for its formation favors de novo synthesis. In this analysis, we studied the formation of S-nitrosothiols by S-transnitrosation, or exchange of -NO for -H between sulfur atoms; we synthesized S-nitroso-glutathionyl-Sepharose 4B beads (SNO-4B) as a reagent with which to measure S-transnitrosation reactions. We detected a maximum of 1.57 +/- 0.24 pmol NO/bead (n = 5) after S-nitrosation of the beads with acidified nitrite. The stability of the S-NO bond was dependent on temperature, but not pH over the 5 to 9 range (except at pH 9 at 37 degrees ), with an estimated t1/2 of 30 hr at 22 degrees C and of approximately 2 wk at 4 degrees C. We demonstrated that SNO-4B transfers -NO to glutathione and to cysteine rapidly and in a pH-dependent manner. The initial rate of transfer of -NO from SNO-4B to glutathione at room temperature was 0.53, 3.03 and 5.14 microM/min at pH 5.0, 7.4 and 9.0, respectively (P < .05). Under the same conditions, the initial rate of -NO transfer to cysteine was 0. 72, 3.71 and 4.69 microM/min at pH 5.0, 7.4 and 9.0, respectively (P < .05). There was no appreciable S-transnitrosation between SNO-4B and bovine serum albumin. We further demonstrated that SNO-4B evokes significant vasodilator and platelet inhibitory responses in plasma-free systems and activates platelet soluble guanylyl cyclase. These data suggest a mechanism by which to explain the metabolic fate and distribution of NO among thiol pools in the vasculature, and implicate S-transnitrosation at the cell surface in NO signal transduction.

Recombinant human macrophage colony-stimulating factor reduces plasma cholesterol and carrageenan granuloma foam cell formation in Watanabe heritable hyperlipidemic rabbits

Previous studies have demonstrated that short-term administration of recombinant human macrophage colony-stimulating factor (rhM-CSF) reduces plasma cholesterol in rabbits, nonhuman primates, and human subjects. This study extended the dose schedule of rhM-CSF to 8 weeks of continuous intravenous infusion (CIV) in the Watanabe heritable hyperlipidemic (WHHL) rabbit and expanded the scope to include an assessment of macrophage-derived foam cell development. Ten male WHHL rabbits were injected subcutaneously with 1% carrageenan to promote formation of a macrophage-rich foam cell granuloma. Rabbits were infused with either vehicle or rhM-CSF at 100 micrograms/kg per day (weeks 1 through 5) followed by 300 micrograms/kg per day (weeks 6 through 8). rhM-CSF (100 micrograms/kg per day) decreased total plasma cholesterol by 45% at 2 weeks compared with controls. The gradual return of plasma cholesterol toward control concentrations over the subsequent 3 weeks correlated with the appearance of circulating antibodies specific to rhM-CSF. Granuloma weights at harvest (8 weeks after infusion) were significantly lower (2.8 +/- 0.7 g, mean +/- SEM) in rhM-CSF-treated rabbits relative to controls (7.1 +/- 1.5 g, P < .05). Granulomas from rabbits treated with rhM-CSF contained lower concentrations of cholesterol (2.0 +/- 0.7 versus 6.1 +/- 1.5 micrograms/mg, P < .03) and cholesteryl ester (0.7 +/- 0.4 versus 3.9 +/- 1.2 micrograms/mg, P < .03) than controls. Histological evaluation revealed that granulomas from the rhM-CSF-treated rabbits were more fibrous and contained fewer foam cells than those from controls.(ABSTRACT TRUNCATED AT 250 WORDS)

PPACK attenuates plasmin-induced changes in endothelial integrity

In order to determine whether plasmin affects endothelial cell integrity directly, confluent bovine aortic endothelial cells were treated with plasminogen and a plasminogen activator. The permeability of the monolayer to [125I]-albumin was shown to be increased significantly (P < 0.01) with a concomitant decrease in viability. Plasmin activity correlated significantly with endothelial cell permeability (p < 0.004; r = 0.82). Coincubation with D-phenylalanyl-L-prolyl-L-arginyl chloromethylketone, a tripeptide inhibitor of plasmin, reduced the increase in endothelial permeability induced by plasmin by 59% (p = 0.033). Monolayers studied in parallel were stained with rhodamine-phalloidin to visualize F-actin. There were significant morphologic changes in the endothelial monolayers exposed to plasmin compared to control monolayers, and these changes could be attenuated by coincubation with D-phenylalanyl-L-prolyl-L-arginyl chloromethylketone. These studies show that: 1) plasmin induces significant increases in endothelial cell permeability with accompanying morphologic changes; and 2) these deleterious functional and morphologic effects can be attenuated by coincubation with the plasmin inhibitor, D-phenylalanyl-L-prolyl-L-arginyl chloromethylketone.

Effect of thrombin inhibition on the dynamics of thrombolysis and on platelet function during thrombolytic therapy

To evaluate the effect of thrombin on the dynamics of thrombolysis, we infused rabbits with heparin or hirudin alone or in conjunction with tissue-type plasminogen activator (t-PA) and monitored the kinetics of fibrinolysis and changes in ex vivo platelet aggregation responses over time. Both heparin and hirudin enhanced total fibrinolysis in an ex vivo arteriovenous shunt preparation: 82 +/- 2% and 79 +/- 2%, respectively, compared with 51 +/- 8% for t-PA alone (P less than 0.05) and 50 +/- 4% for t-PA plus aspirin (p less than 0.05). Heparin coadministered with t-PA significantly reduced the half-time for clot lysis compared with t-PA alone (p less than 0.05), whereas hirudin coadministered with t-PA significantly reduced the half-time for clot lysis compared with that for t-PA alone, t-PA plus aspirin, and t-PA plus heparin (5.5 +/- 0.6 versus 12.1 +/- 2.0 versus 12.6 +/- 2.2 versus 10.0 +/- 0.8 minutes, respectively; p less than 0.05). Both heparin and hirudin prevented the increase in ADP-induced platelet aggregation normally seen with t-PA alone (p less than 0.01 by t test; p less than 0.05 by two-way analysis of variance). These data demonstrate that selective, antithrombin III-independent thrombin inhibitors can enhance the efficacy of thrombolysis by modulating the dynamics of the process and preventing platelet activation associated with plasminogen activator therapy.

Thrombolytic therapy causes an increase in vascular permeability that is reversed by 1-deamino-8-D-vasopressin

BACKGROUND

To examine the effect of plasminogen activator therapy on vascular permeability, we used a modified rabbit mesenteric model of extravascular tissue accumulation of radiolabeled albumin.

METHODS AND RESULTS

Albumin deposition was measured after saline, tissue-type plasminogen activator (t-PA; 0.86 mg/kg for 1 hour followed by 0.29 mg/kg for 2 hours), or t-PA plus 1-deamino-8-D-arginine vasopressin (DDAVP; 0.6 mg/kg/hr for 30 minutes) infusion in animals with or without aspirin (ASA; 15-mg/kg bolus) pretreatment. In animals not given ASA, t-PA caused a 240% increase in tissue [125I]albumin accumulation over time (p less than 0.001). DDAVP prevented the rise in albumin accumulation normally seen with t-PA alone (p less than 0.05) in animals not given ASA. In animals pretreated with ASA, t-PA similarly caused an increase in tissue albumin accumulation, but this was significantly attenuated from that of animals not given ASA (p less than 0.03). Interestingly, DDAVP failed to block the response to t-PA in the animals given ASA. Because increases in vascular permeability correlated with increases in bleeding time (r = 0.37, p less than 0.03), these data suggest that the effect of plasmin generation on vascular permeability may contribute to the bleeding tendency seen with thrombolytic therapy. The ability of DDAVP to reverse the bleeding tendency and bleeding time may be due in part to its reversal of the increased vascular permeability induced by the administration of plasminogen activators.

CONCLUSIONS

These data show that plasminogen activation causes an increase in vascular permeability that is inhibited by DDAVP; ASA blunts this action of t-PA and prevents the DDAVP blockade of the increase in permeability induced by t-PA in this rabbit model.

Bleeding time prolongation with streptokinase and its reduction with 1-desamino-8-D-arginine vasopressin

The mechanism by which treatment with thrombolytic agents causes bleeding is not known. Recently, frequency of bleeding events has been shown to correlate with bleeding time, particularly in individuals treated with aspirin. We examined the effects of streptokinase (20,000-60,000 IU/kg) on bleeding time in 40 rabbits pretreated with aspirin, a model for fibrinolytic therapy. We then tested the effects of 1-desamino-8-D-arginine vasopressin (DDAVP) (0.3 microgram/kg), an agent known to reduce bleeding time in a variety of bleeding disorders, in 20 rabbits and compared the results with those of a control group of rabbits receiving normal saline placebo. Aspirin increased the bleeding time from a baseline mean +/- SEM value of 119 +/- 15 to 191 +/- 34 seconds in the control group and from 114 +/- 6 to 188 +/- 18 seconds in the experimental group. The addition of streptokinase increased the bleeding time to 592 +/- 119 seconds in the control group and 810 +/- 114 seconds in the experimental group (p = NS). Subsequent infusion of DDAVP decreased the bleeding time in the experimental group to 302 +/- 29 seconds (p less than 0.01 versus streptokinase) compared with 572 +/- 79 seconds (p = NS versus streptokinase) in the control animals given saline placebo. In a subset of rabbits receiving aspirin and streptokinase (40,000-60,000 IU/kg), samples were obtained for platelet aggregation (n = 16), von Willebrand factor antigen concentration (n = 17), and von Willebrand factor multimer distribution (n = 14). Maximal rates of ADP-induced platelet aggregation were not affected by DDAVP infusion, nor was the plasma concentration of von Willebrand factor antigen, quantified by an immunoradiometric assay, significantly affected by DDAVP infusion. Furthermore, the von Willebrand factor multimer ratio decreased with DDAVP administration. These findings indicate that aspirin and streptokinase combined result in a marked increase in bleeding time that can be reduced by DDAVP. This effect of DDAVP is not accompanied by an increase in platelet aggregation response, plasma von Willebrand factor antigen concentration, or von Willebrand factor multimer ratio.

Temporal effects of thrombolytic agents on platelet function in vivo and their modulation by prostaglandins

To examine the temporal effects of plasmin generated in vivo on platelet function, we infused tissue-type plasminogen activator (t-PA) in rabbits over 3 hours and measured ex vivo platelet aggregation. We noted an initial increase in the aggregation response to ADP occurring 30 minutes after the start of infusion. This enhanced response was short-lived and by 180 minutes was reduced, compared with pretreatment levels. Baseline aggregation response was restored by 240 minutes. This pattern of aggregation response to t-PA infusion was also seen with thrombin as the agonist. Coinfusion of either prostaglandin I2 or prostaglandin E1 abolished the initial hyperaggregable phase induced by t-PA; the hypoaggregable phase occurred earlier (after 60 minutes) and persisted throughout the 1-hour recovery period. Similarly, streptokinase infused for 1 hour also increased platelet aggregation at early times and then reduced aggregation responses after the first hour. Plasma plasmin activity increased as expected with t-PA infusion alone, peaking at 30 minutes and returning to baseline by the first hour. Interestingly, prostaglandin E1 blunted the rise in plasma plasmin activity. This same dose of prostaglandin E1 or prostaglandin I2 used alone did not appreciably alter platelet function at any time during the experiment. Our data show that therapeutic doses of t-PA or streptokinase produce a biphasic effect on platelet aggregation response in the rabbit. Coinfusion of either of the antiplatelet agents, prostaglandin E1 or prostaglandin I2, abolishes the hyperaggregable phase and prolongs the inhibitory effects on platelet aggregation produced by t-PA. These data suggest that the effects of thrombolytic agents on platelet function are complex and can be modulated by antiplatelet prostaglandins.

Plasma membrane enrichment with cis-unsaturated fatty acids enhances LDL metabolism in U937 monocytes

The mechanism by which dietary cis-unsaturated fatty acids lower low density lipoprotein (LDL) cholesterol is unknown. Because cis-unsaturated fatty acids incorporated into cell membranes increase membrane fluidity and, as a result, can alter membrane-dependent cell functions, we examined LDL binding, uptake, and degradation in upregulated U937 monocytes enriched in membrane oleate, a monounsaturated fatty acid, and membrane linoleate, a polyunsaturated fatty acid. The same parameters were also examined in upregulated U937 monocytes enriched in membrane stearate, a saturated fatty acid, and in upregulated, unmodified U937 monocytes. Monocytes enriched in cis-unsaturated fatty acids exhibited augmented LDL binding, internalization, and degradation compared with both stearate-enriched monocytes and unmodified monocytes. The molar potency of linoleate in augmenting LDL metabolism was 50% greater than that of oleate. Enrichment with oleate and linoleate resulted in a decrease in the fatty acyl mole-weighted melting point of the plasma membrane and an increase in plasma membrane fluidity, as indicated by a reduction in the steady-state fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene incorporated into the membrane. Stearate-enriched monocytes exhibited a slight increase in the plasma membrane fatty acyl mole-weighted melting point and essentially no change in plasma membrane fluidity. Thus, one mechanism by which cis-unsaturated fatty acids lower LDL cholesterol may involve alteration in membrane lipid composition and physical properties, thereby leading to an increase in cellular clearance of this atherogenic lipoprotein.

Effect of dietary fat saturation and cholesterol on low density lipoprotein degradation by mononuclear cells of Cebus monkeys

The mechanism by which dietary unsaturated fatty acids lower low density lipoprotein (LDL) cholesterol is unknown. Unsaturated fatty acids incorporated into the cell membrane can increase membrane fluidity and, as a result, dramatically alter membrane-dependent cell functions. Therefore, we examined the effect of long-term dietary consumption of corn oil and coconut oil with and without cholesterol in amounts equivalent to those of a typical Western diet on the degradation of human LDL by peripheral blood mononuclear cells in Cebus albifrons monkeys. Cellular LDL degradation was dramatically enhanced in the mononuclear cells isolated from animals fed corn oil in comparison with those from animals fed coconut oil. The addition of cholesterol to the diets resulted in a slight attenuation of LDL degradation in the corn oil group while no effect was noted in the coconut oil group. Crossover LDL binding and degradation experiments with LDL isolated from animals fed corn oil diets and coconut oil diets demonstrated increased binding and degradation of LDL in mononuclear cells from animals fed corn oil diets. Enhanced mononuclear cell LDL degradation was accompanied by increased cellular cis-unsaturated fatty acyl content, increased membrane fluidity, and decreased plasma cholesterol. Increased cellular cis-unsaturated fatty acyl content with its concomitant increase in membrane fluidity mirrored the dietary lipid profile of the host animal. A linear relationship was observed between cellular LDL degradation and both cellular cis-unsaturated fatty acyl content and membrane fluidity. These observations parallel results noted in whole-animal LDL catabolic studies with these same animals described elsewhere. These data suggest a novel mechanism by which dietary unsaturated fatty acids exert their LDL-lowering effect.

Atrial natriuretic factor-specific antibody as a tool for physiological studies. Evidence for role of atrial natriuretic factor in aldosterone and renal electrolyte regulation

Numerous studies have shown that administration of atrial natriuretic factor (ANF) increases urinary sodium excretion and urine flow, decreases blood pressure, and inhibits renin and aldosterone release. However, the role of endogenous ANF in the regulation of renal sodium excretion, blood pressure, plasma renin activity, and aldosterone level remains to be elucidated. To examine this issue, endogenous ANF was blocked by administering rat ANF-(99-126) specific antiserum (Ab) to anesthetized rats (n = 7). Control animals received either no injection (time controls, n = 10) or preimmune serum (n = 8). Blockade of endogenous ANF caused a 28 +/- 0.09%, 47 +/- 0.08%, and 51 +/- 0.08% fall in sodium excretion at 15, 30, and 45 minutes after Ab injection (p less than 0.05, p less than 0.01, p less than 0.01, respectively). Urine flow fell 35 +/- 7% at 45 minutes after ANF inhibition (p less than 0.05). Plasma ANF levels were suppressed to undetectable levels. However, there were no changes in blood pressure throughout the experiment nor plasma renin concentration when measured at 45 minutes after Ab injection. Interestingly, plasma aldosterone concentration increased significantly (by approximately 50%, p less than 0.025), in response to Ab. Completeness of blockade was demonstrated by the absence of sodium excretion response to exogenous ANF (500 ng). In either the time control or the preimmune serum group, urinary excretion, blood pressure, plasma ANF, plasma renin concentration, and plasma aldosterone concentration were unchanged throughout the experiment. In contrast to the Ab group, a challenge with exogenous ANF (500 ng) increased sodium excretion by 2.17 mueq/min in the preimmune serum group.(ABSTRACT TRUNCATED AT 250 WORDS)

Frequency of hypercholesterolemia after cardiac transplantation

Cardiac transplant patients are prone to accelerated coronary atherosclerosis. The mechanism by which this process occurs is not yet known, although immunologically mediated arterial injury is thought to play a primary role in its pathogenesis. Despite immunosuppressive potency, patients treated with cyclosporin A remain at significant risk for the development of accelerated atherosclerosis. It is hypothesized that cyclosporin A's hepatotoxic effects might contribute to the atherosclerotic process by impairing low density lipoprotein hepatic clearance in transplant patients, which would be reflected in a more atherogenic lipoprotein profile. To test this hypothesis, serum cholesterol levels were analyzed after transplantation. Significant and progressive increases in total cholesterol and in the total-to-high density lipoprotein cholesterol ratio were found. This atherogenic lipoprotein profile may contribute to accelerated atherosclerosis in cardiac transplant patients treated with cyclosporin A.

Unsaturated fatty acids enhance low density lipoprotein uptake and degradation by peripheral blood mononuclear cells

The precise mechanism by which unsaturated fatty acids lower low density lipoprotein cholesterol is not known. Because cis-unsaturated fatty acids incorporated in cell membranes increase membrane fluidity and can thereby dramatically alter membrane-dependent cellular functions, we examined the effect of linoleate and oleate incorporation in peripheral blood mononuclear cell membranes on the physical properties of the membrane and concomitantly on low density lipoprotein uptake and degradation. We found that membrane enrichment with linoleate increased the rate of low density lipoprotein degradation in both freshly isolated and derepressed mononuclear cells. Enrichment with oleate led to similar increases in degradation. "Specific" low density lipoprotein uptake by derepressed cells was also enhanced by linoleate and oleate incorporation. Enrichment with both of these fatty acids produced an increase in membrane fluidity, as indicated by a reduction in the steady-state fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene incorporated in the membrane. In contrast, stearate enrichment had little effect on uptake or degradation of low density lipoprotein, nor did it affect membrane fluidity. These data point to a novel mechanism for the reduction in low density lipoprotein produced by unsaturated fatty acids that involves their physical effects on cell membranes as it relates to metabolism of the lipoprotein.

Acute renal denervation produces a diuresis and natriuresis in young SHR but not WKY rats

Clearance experiments were conducted to determine the effect of acute unilateral renal denervation (DNX) on renal hemodynamics and salt and water excretion in anesthetized 6-wk-old spontaneously hypertensive rats (SHR) and Wistar-Kyoto genetic control rats (WKY). Before DNX, SHR had higher mean arterial pressure (33%) and renal vascular resistance (RVR) (57%) and lower glomerular filtration rate (GFR) (10%); urine flow and sodium excretion were similar. Following DNX in SHR, sodium and water excretion increased by 138 and 62%, respectively (P less than 0.001); GFR and RVR were unchanged. In contrast, DNX in WKY did not affect urine flow (0%) or sodium excretion (-21%). These strain differences were observed in Okamoto-Aoki rats from two sources. Effective DNX was indicated by 95% reduction of norepinephrine content 3 days after DNX in both strains. Six-week-old Sprague-Dawley and Munich-Wistar rats, in contrast to WKY, responded to DNX with a natriuresis (+182%) and diuresis (+95%) (P less than 0.001). Renal function was unaffected by sham DNX in SHR. Our results indicate that efferent renal nerve activity has little tonic influence on the renal vasculature in these young rats. Augmented neurotransmitter release and/or tubular responsiveness may be involved in fluid and electrolyte retention and the pathogenesis of hypertension in SHR. Conversely, blunted renal neuroeffector responses may prevent WKY from developing hypertension.