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Stahl JE, Nelson WA. Applying the Peter Parker Principle to Healthcare. Camb Q Healthc Ethics 2024; 33:271-274. [PMID: 36524241 DOI: 10.1017/s0963180122000275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The role of power in healthcare can raise many ethical challenges. Power is ownership, whether given, ceded, or taken of another person's autonomy. When a person has power over someone else, they can control or strongly influence the decision-making freedom of that person. From the principalist perspective1,2 of healthcare ethics, denying a person their freedom to choose, should only occur when justifying conditions related to beneficence and nonmaleficence are sufficiently satisfied. In healthcare, it is rare to be able to identify situations where paternalism is justified. However, experience suggests that abusive power in healthcare is used too frequently without justifying criteria.
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Affiliation(s)
- James E Stahl
- The Dartmouth Institute of Health Policy and Clinical Practice, Geisel School of Medicine at Dartmouth, Section of General Internal Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire03766, USA
| | - William A Nelson
- Ethics and Human Values Program, The Dartmouth Institute of Health Policy and Clinical Practice, Department of Medical Education, Elizabeth DeCamp McInerny Professorship, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire03755, USA
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2
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Turner K, Lahey T, Gremmels B, Lesandrini J, Nelson WA. Organizational Ethics in Healthcare: A National Survey. HEC Forum 2024:10.1007/s10730-023-09520-3. [PMID: 38231425 DOI: 10.1007/s10730-023-09520-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/20/2023] [Indexed: 01/18/2024]
Abstract
Organizational ethics-defined as the alignment of an institution's practices with its mission, vision, and values-is a growing field in health care not well characterized in empirical literature. To capture the scope and context of organizational ethics work in United States healthcare institutions, we conducted a nationwide convenience survey of ethicists regarding the scope of organizational ethics work, common challenges faced, and the organizational context in which this work is done. In this article, we report substantial variability in the structure of organizational ethics programs and the settings in which it is conducted. Notable findings included disagreement about the activities that comprise organizational ethics and a lack of common metrics used to assess organizational ethics activities. A frequently cited barrier to full engagement in these activities was poor institution-wide understanding about the role and function of organizational ethics resources. These data suggest a tension in the trajectory of organizational ethics' professionalization: while some variability is appropriate to the field's relative youth, inadequate attention to definitions of organizational ethics practice and metrics for success can impede discussions about appropriate institutional support, leadership context, and training for practitioners.
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Affiliation(s)
- Kelly Turner
- Gnaegi Center for Health Care Ethics, Saint Louis University, Saint Louis, MO, USA.
| | - Tim Lahey
- University of Vermont Medical Center, Burlington, VT, USA
| | | | | | - William A Nelson
- Geisel School of Medicine at Dartmouth College, Hanover, NH, USA
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Lee TM, Smith RA, Nelson WA, Day T, Sato Y. No life-history cost of tebufenozide resistance in the smaller tea tortrix moth. Pest Manag Sci 2023; 79:2581-2590. [PMID: 36869740 DOI: 10.1002/ps.7439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 03/04/2023] [Indexed: 06/02/2023]
Abstract
BACKGROUND Tebufenozide is widely used to control populations of the smaller tea tortrix, Adoxophyes honmai. However, A. honmai has evolved resistance such that straightforward pesticide application is an untenable long-term approach for population control. Evaluating the fitness cost of resistance is key to devising a management strategy that slows the evolution of resistance. RESULTS We used three approaches to assess the life-history cost of tebufenozide resistance with two strains of A. honmai: a tebufenozide-resistant strain recently collected from the field in Japan and a susceptible strain that has been maintained in the laboratory for decades. First, we found that the resistant strain with standing genetic variation did not decline in resistance in the absence of insecticide over four generations. Second, we found that genetic lines that spanned a range of resistance profiles did not show a negative correlation between their LD50 , the dosage at which 50 % of individuals died, and life-history traits that are correlates of fitness. Third, we found that the resistant strain did not manifest life-history costs under food limitation. Our crossing experiments indicate that the allele at an ecdysone receptor locus known to confer resistance explained much of the variance in resistance profiles across genetic lines. CONCLUSION Our results indicate that the point mutation in the ecdysone receptor, which is widespread in tea plantations in Japan, does not carry a fitness cost in the tested laboratory conditions. The absence of a cost of resistance and the mode of inheritance have implications for which strategies may be effective in future resistance management efforts. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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Affiliation(s)
- Tingyat M Lee
- Department of Biology, Queen's University, Kingston, Canada
| | - R A Smith
- Department of Biology, Queen's University, Kingston, Canada
| | | | - Troy Day
- Department of Mathematics and Statistics, Queen's University, Kingston, Canada
| | - Yasushi Sato
- Institute for Plant Protection, NARO, Shimada, Japan
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4
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Holmes LA, Nelson WA, Lougheed SC. Strong effects of food quality on host life history do not scale to impact parasitoid efficacy or life history. Sci Rep 2023; 13:3528. [PMID: 36864085 PMCID: PMC9981602 DOI: 10.1038/s41598-023-30441-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 02/23/2023] [Indexed: 03/04/2023] Open
Abstract
Parasitoids are small insects, (e.g., small wasps or flies) that reproduce by laying eggs on or within host arthropods. Parasitoids make up a large proportion of the world's biodiversity and are popular agents of biological control. Idiobiont parasitoids paralyze their hosts upon attack and thus are expected to only target hosts large enough to support offspring development. Host resources generally impact host attributes and life histories including size, development, and life span. Some argue slow host development in response to resource quality increases parasitoid efficacy (i.e., a parasitoid's ability to successfully reproduce on or within a host) due to longer host exposure to parasitoids. However, this hypothesis is not always supported and does not consider variation in other host traits in response to resources that may be important for parasitoids (e.g., variation in host size is known to impact parasitoid efficacy). In this study we test whether trait variation within host developmental stages in response to host resources is more important for parasitoid efficacy and life histories than trait variation across host developmental stages. We exposed seed beetle hosts raised on a food quality gradient to mated female parasitoids and measured the number of hosts parasitized and parasitoid life history traits at the scale of host stage- and age-structure. Our results suggest host food quality does not cascade to impact idiobiont parasitoid life histories despite large food quality effects on host life history. Instead, variation in host life histories across host developmental stages better predicts parasitoid efficacy and life histories, suggesting finding a host in a specific instar is more important for idiobiont parasitoids than finding hosts on or within higher quality resources.
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Affiliation(s)
- Leslie A. Holmes
- grid.47609.3c0000 0000 9471 0214University of Lethbridge, 4401 University Drive West, Lethbridge, AB T1K 3M4 Canada
| | - William A. Nelson
- grid.410356.50000 0004 1936 8331Queen’s University, 116 Barrie Street, Kingston, ON K7L 3N6 Canada
| | - Stephen C. Lougheed
- grid.410356.50000 0004 1936 8331Queen’s University, 116 Barrie Street, Kingston, ON K7L 3N6 Canada
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Hertel NE, Biegalski SR, Nelson VI, Nelson WA, Mukhopadhyay S, Su Z, Chan AM, Kesarwala AH, Dynan WS. Compact portable sources of high-LET radiation: Validation and potential application for galactic cosmic radiation countermeasure discovery. Life Sci Space Res (Amst) 2022; 35:163-169. [PMID: 36336362 DOI: 10.1016/j.lssr.2022.10.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 09/28/2022] [Accepted: 10/04/2022] [Indexed: 06/16/2023]
Abstract
Implementation of a systematic program for galactic cosmic radiation (GCR) countermeasure discovery will require convenient access to ground-based space radiation analogs. The current gold standard approach for GCR simulation is to use a particle accelerator for sequential irradiation with ion beams representing different GCR components. This has limitations, particularly for studies of non-acute responses, strategies that require robotic instrumentation, or implementation of complex in vitro models that are emerging as alternatives to animal experimentation. Here we explore theoretical and practical issues relating to a different approach to provide a high-LET radiation field for space radiation countermeasure discovery, based on use of compact portable sources to generate neutron-induced charged particles. We present modeling studies showing that DD and DT neutron generators, as well as an AmBe radionuclide-based source, generate charged particles with a linear energy transfer (LET) distribution that, within a range of biological interest extending from about 10 to 200 keV/μm, resembles the LET distribution of reference GCR radiation fields experienced in a spacecraft or on the lunar surface. We also demonstrate the feasibility of using DD neutrons to induce 53BP1 DNA double-strand break repair foci in the HBEC3-KT line of human bronchial epithelial cells, which are widely used for studies of lung carcinogenesis. The neutron-induced foci are larger and more persistent than X ray-induced foci, consistent with the induction of complex, difficult-to-repair DNA damage characteristic of exposure to high-LET (>10 keV/μm) radiation. We discuss limitations of the neutron approach, including low fluence in the low LET range (<10 keV/μm) and the absence of certain long-range features of high charge and energy particle tracks. We present a concept for integration of a compact portable source with a multiplex microfluidic in vitro culture system, and we discuss a pathway for further validation of the use of compact portable sources for countermeasure discovery.
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Affiliation(s)
- Nolan E Hertel
- G. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 770 State Street, 30332-0745 Atlanta, GA, United States of America.
| | - Steven R Biegalski
- G. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 770 State Street, 30332-0745 Atlanta, GA, United States of America
| | - Victoria I Nelson
- G. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 770 State Street, 30332-0745 Atlanta, GA, United States of America
| | - William A Nelson
- G. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 770 State Street, 30332-0745 Atlanta, GA, United States of America
| | - Sharmistha Mukhopadhyay
- G. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 770 State Street, 30332-0745 Atlanta, GA, United States of America
| | - Zitong Su
- Department of Radiation Oncology and Winship Cancer Institute, Emory University School of Medicine, 1365 Clifton Road NE, 30322 Atlanta GA, United States of America; Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Road NE, 30322 Atlanta GA, United States of America
| | - Alexis M Chan
- Department of Radiation Oncology and Winship Cancer Institute, Emory University School of Medicine, 1365 Clifton Road NE, 30322 Atlanta GA, United States of America; Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Road NE, 30322 Atlanta GA, United States of America
| | - Aparna H Kesarwala
- Department of Radiation Oncology and Winship Cancer Institute, Emory University School of Medicine, 1365 Clifton Road NE, 30322 Atlanta GA, United States of America
| | - William S Dynan
- Department of Radiation Oncology and Winship Cancer Institute, Emory University School of Medicine, 1365 Clifton Road NE, 30322 Atlanta GA, United States of America; Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Road NE, 30322 Atlanta GA, United States of America.
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Joncour B, Nelson WA, Pak D, Bjørnstad ON. An integrated experimental and mathematical approach to inferring the role of food exploitation and interference interactions in shaping life history. Funct Ecol 2022. [DOI: 10.1111/1365-2435.14022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Barbara Joncour
- Department of Biology Queen’s University Kingston ON K7L 3N6 Canada
| | | | - Damie Pak
- Department of Biology Pennsylvania State University University Park PA 16802 Pennsylvania USA
| | - Ottar N. Bjørnstad
- Departments of Entomology and Biology Pennsylvania State University University Park PA 16802 Pennsylvania USA
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Lee TM, Westbury KM, Martyniuk CJ, Nelson WA, Moyes CD. Metabolic Phenotype of Daphnia Under Hypoxia: Macroevolution, Microevolution, and Phenotypic Plasticity. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.822935] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Daphnia is a freshwater crustacean that is able to upregulate hemoglobin (Hb) in response to hypoxia, imparting a red color. We combine multiple field surveys across season with a lab experiment to evaluate changes in the metabolic phenotype of Daphnia in relation to environmental hypoxia. Looking at the zooplankton community, we found that D. pulicaria was restricted to lakes with a hypoxic hypolimnion. Comparing D. pulicaria with different amounts of Hb, red animals showed higher mRNA levels for several Hb genes, whereas most glycolytic genes showed red/pale differences of less than 50%. We also observed seasonal changes in the metabolic phenotype that differed between red and pale animals. Hb was upregulated early in the season in hypoxic lakes, and a relationship between Hb and lactate dehydrogenase only emerged later in the season in a temporal pattern that was lake specific. To evaluate whether these differences were due to specific lake environments or microevolutionary differences, we tested the induction of genes under controlled hypoxia in isofemale lines from each of four lakes. We found a strong response to 18 h hypoxia exposure in both Hb and lactate dehydrogenase mRNA, although the magnitude of the acute response was greater than the steady state differences in mRNA levels between pale and red Daphnia. The baseline expression of Hb and lactate dehydrogenase also varied between isofemale lines with different lake origins. These results, in combination with comparison of glycogen measurements, suggests that Hb functions primarily to facilitate oxygen delivery, mitigating systemic hypoxia, rather than an oxygen store. The combination of lab and field studies suggest that the metabolic phenotype of the animal is influenced by both microevolutionary differences (within and between lakes) as well as the spatial and temporal environmental heterogeneity of the lakes. The differences between Daphnia species, and the unexpected lack of hypoxia sensitivity of select glycolytic genes provide evidence of macroevolutionary differences in metabolic strategies to cope with hypoxia.
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Joncour B, Nelson WA. Sublethal concentration of insecticide amplifies interference competition in a tortrix moth. Ecotoxicol Environ Saf 2021; 220:112324. [PMID: 34015630 DOI: 10.1016/j.ecoenv.2021.112324] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2020] [Revised: 04/30/2021] [Accepted: 05/06/2021] [Indexed: 06/12/2023]
Abstract
Insecticides are extensively used worldwide to kill insect pests, yet organisms are most often exposed to insecticides at sublethal concentrations. Our understanding of sublethal effects on life histories is needed to predict the impact of insecticides on population dynamics and improve insecticide use and pest control. Sublethal concentrations can impact life histories directly and indirectly through changes in the intraspecific competition. Yet, few studies have evaluated the sublethal effects on intraspecific competition and these do not disentangle the insecticide effects on interference competition versus exploitative competition. As such, sublethal effects on the relative contribution of each pathways in shaping life histories are largely unknown, despite the fact that this can impact population dynamics. In this study, we focused on the neurotoxic insecticide spinosad and investigated its sublethal effects on interference among the aggressive larvae of the tortrix moth Adoxophyes honmai and the consequences for life histories. We conducted a set of paired experiments to disentangle the insecticide effects on interference from the ones on exploitation. Spinosad was found to amplify interference with most effects on mortality which lets us suggest that the insecticide likely increases the level of aggressive interactions resulting in more conspecific killings (e.g. cannibalism). Spinosad exposure was found to impair movement ability. Less movements may increase susceptibility to conspecific attacks and or increase aggresivity for better defence, two plausible mechanisms that could explain the increase in interference with insecticide. This study shows that insecticide at sublethal concentration can impact life histories by altering the strength of interference competition. Many organisms (pest and non-target species) compete through interference and theory predicts that a change in interference can substantially change dynamics. Our finding therefore reveals the importance of assessing the effect of insecticides on the mechanisms of competition when predicting their impact on populations.
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Affiliation(s)
- Barbara Joncour
- Department of Biology, Queen's University, 116 Barrie Street, Kingston K7L 3N6, ON, Canada.
| | - William A Nelson
- Department of Biology, Queen's University, 116 Barrie Street, Kingston K7L 3N6, ON, Canada
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9
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Forsythe AB, Day T, Nelson WA. Demystifying individual heterogeneity. Ecol Lett 2021; 24:2282-2297. [PMID: 34288328 DOI: 10.1111/ele.13843] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 06/07/2021] [Accepted: 06/14/2021] [Indexed: 12/01/2022]
Abstract
Among-individual variation in vital rates, such as mortality and birth rates, exists in nearly all populations. Recent studies suggest that this individual heterogeneity produces substantial life-history and fitness differences among individuals, which in turn scale up to influence population dynamics. However, our ability to understand the consequences of individual heterogeneity is limited by inconsistencies across conceptual frameworks in the field. Studies of individual heterogeneity remain filled with contradicting and ambiguous terminology that introduces risks of misunderstandings, conflicting models and unreliable conclusions. Here, we synthesise the existing literature into a single and comparatively straightforward framework with explicit terminology and definitions. This work introduces a distinction between potential vital rates and realised vital rates to develop a coherent framework that maps directly onto mathematical models of individual heterogeneity. We suggest the terms "fixed condition" and "dynamic condition" be used to distinguish potential vital rates that are permanent from those that can change throughout an individual's life. To illustrate, we connect the framework to quantitative genetics models and to common classes of statistical models used to infer individual heterogeneity. We also develop a population projection matrix model that provides an example of how our definitions are translated into precise quantitative terms.
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Affiliation(s)
- Amy B Forsythe
- Department of Biology, Biosciences Complex, Queen's University, Kingston, ON, Canada
| | - Troy Day
- Department of Biology, Biosciences Complex, Queen's University, Kingston, ON, Canada.,Department of Mathematics and Statistics, Queen's University, Kingston, ON, Canada
| | - William A Nelson
- Department of Biology, Biosciences Complex, Queen's University, Kingston, ON, Canada
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10
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Affiliation(s)
| | | | - Markus Dyck
- Department of Environment Government of Nunavut Igloolik NU Canada
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11
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Holmes LA, Nelson WA, Lougheed SC. Food quality effects on instar-specific life histories of a holometabolous insect. Ecol Evol 2020; 10:626-637. [PMID: 32015831 PMCID: PMC6988550 DOI: 10.1002/ece3.5790] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 08/27/2019] [Accepted: 09/21/2019] [Indexed: 11/10/2022] Open
Abstract
It is a long-standing challenge to understand how changes in food resources impact consumer life history traits and, in turn, impact how organisms interact with their environment. To characterize food quality effects on life history, most studies follow organisms throughout their life cycle and quantify major life events, such as age at maturity or fecundity. From these studies, we know that food quality generally impacts body size, juvenile development, and life span. Importantly, throughout juvenile development, many organisms develop through several stages of growth that can have different interactions with their environment. For example, some parasitoids typically attack larger instars, whereas larval insect predators typically attack smaller instars. Interestingly, most studies lump all juvenile stages together, which ignores these ecological changes over juvenile development.We combine a cross-sectional experimental approach with a stage-structured population model to estimate instar-specific vital rates in the bean weevil, Callosobruchus maculatus across a food quality gradient. We characterize food quality effects on the bean weevil's life history traits throughout its juvenile ontogeny to test how food quality impacts instar-specific vital rates.Vital rates differed across food quality treatments within each instar; however, their effect differed with instar. Weevils consuming low-quality food spent 38%, 37%, and 18% more time, and were 34%, 53%, and 63% smaller than weevils consuming high-quality food in the second, third, and fourth instars, respectively. Overall, our results show that consuming poor food quality means slower growth, but that food quality effects on vital rates, growth and development are not equal across instars. Differences in life history traits over juvenile ontogeny in response to food quality may impact how organisms interact with their environment, including how susceptible they are to predation, parasitism, and their competitive ability.
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12
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deSante-Bertkau JE, Shubkin CD, Nelson WA, Salter EK, Lantos JD. When Specialty Care Is Unavailable to Rural Families. Pediatrics 2019; 144:peds.2019-1130. [PMID: 31690711 DOI: 10.1542/peds.2019-1130] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/17/2019] [Indexed: 11/24/2022] Open
Abstract
We present the case of a 2-year-old boy with epidermolysis bullosa and supraglottic stenosis whose parents refuse an elective tracheostomy because of the significant care the tracheostomy would require. The patient's family lives in a rural area with few health care resources and his parents are already handling hours of daily skin care for his epidermolysis bullosa. In an attempt to convince the parents to pursue the intervention, the medical team recommends that the family move to an area with additional resources to assist in the child's care. The parents refuse to move, citing the many benefits their home environment provides for their son. The medical team calls an ethics consultation, questioning whether this decision constitutes medical neglect. This case raises important questions about medical decision-making in pediatrics. First, is a parent's refusal of a recommended medical intervention because it would require moving their family to a new environment a reasonable decision? Second, how broadly can parents define their child's best interest? Should only physical interests be included when making medical decisions? Is there a limit to what can be considered a relevant interest? Third, can parents only consider the interests of the individual child, or can they consider the interests of other members of the family? Finally, what is the threshold for overruling a parental decision? Is it whenever the parent's definition of a patient's best interest is different from the medical team's, or do other criteria have to be met?
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Affiliation(s)
- Jennifer E deSante-Bertkau
- Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.,Department of Pediatrics, College of Medicine, University of Cincinnati, Cincinnati, Ohio
| | - Catherine D Shubkin
- Children's Hospital at Dartmouth-Hitchcock, Lebanon, New Hampshire.,Department of Pediatrics, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire
| | - William A Nelson
- Department of Pediatrics, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire.,The Dartmouth Institute for Health Policy and Clinical Practice, Lebanon, New Hampshire
| | - Erica K Salter
- Gnaegi Center for Health Care Ethics, Saint Louis University, St Louis, Missouri.,Cardinal Glennon Children's Hospital, St Louis, Missouri; and
| | - John D Lantos
- Children's Mercy Kansas City and School of Medicine, University of Missouri-Kansas City, Kansas City, Missouri
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Abstract
Abstract
Many populations have intraspecific diversity in phenotype and ecological strategy, but the mechanisms maintaining such diversity are not fully understood. Multiple behaviors can be maintained either as a conditional strategy, where fitness depends on an individual’s phenotype, or as a mixed strategy, where alternative behaviors have similar fitness independent of phenotype. Using high-resolution depth and time sampling, we characterize 2 distinct diel vertical migration behaviors in a population of freshwater zooplankton (Daphnia pulicaria). Individuals in this population differ in their color phenotype and migratory behavior with red morphs upregulating hemoglobin and undergoing a deep migration and pale morphs not producing hemoglobin and undergoing a shallow migration. We experimentally manipulated the behavior of each phenotype in the field and measured population growth in their natural migration behavior as well as population growth in their alternative behaviors. Experimental populations of pale and red morphs under their natural migrations had roughly equal fitness, despite vast differences in environmental conditions. When forced to switch behaviors, pale morphs suffered reduced fitness, whereas red morphs had similar fitness compared with their natural migration. Our results suggest that although behavioral diversity may be promoted by the opportunity for alternative behaviors of equal fitness, the distinct physiological conditions required for survival in alternative behaviors limit the capacity for individual behavioral switching and likely maintain behavioral diversity as a conditional strategy.
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Affiliation(s)
- G Adam Meyer
- Department of Biology, Queen’s University, Kingston, Ontario
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Huijben S, Chan BHK, Nelson WA, Read AF. The impact of within-host ecology on the fitness of a drug-resistant parasite. Evol Med Public Health 2018; 2018:127-137. [PMID: 30087774 PMCID: PMC6061792 DOI: 10.1093/emph/eoy016] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 06/18/2018] [Indexed: 02/05/2023]
Abstract
Background and objectives The rate of evolution of drug resistance depends on the fitness of resistant pathogens. The fitness of resistant pathogens is reduced by competition with sensitive pathogens in untreated hosts and so enhanced by competitive release in drug-treated hosts. We set out to estimate the magnitude of those effects on a variety of fitness measures, hypothesizing that competitive suppression and competitive release would have larger impacts when resistance was rarer to begin with. Methodology We infected mice with varying densities of drug-resistant Plasmodium chabaudi malaria parasites in a fixed density of drug-sensitive parasites and followed infection dynamics using strain-specific quantitative PCR. Results Competition with susceptible parasites reduced the absolute fitness of resistant parasites by 50–100%. Drug treatment increased the absolute fitness from 2- to >10 000-fold. The ecological context and choice of fitness measure was responsible for the wide variation in those estimates. Initial population growth rates poorly predicted parasite abundance and transmission probabilities. Conclusions and implications (i) The sensitivity of estimates of pathogen fitness to ecological context and choice of fitness measure make it difficult to derive field-relevant estimates of the fitness costs and benefits of resistance from experimental settings. (ii) Competitive suppression can be a key force preventing resistance from emerging when it is rare, as it is when it first arises. (iii) Drug treatment profoundly affects the fitness of resistance. Resistance evolution could be slowed by developing drug use policies that consider in-host competition.
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Affiliation(s)
- Silvie Huijben
- Departments of Biology and Entomology, Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, USA
| | - Brian H K Chan
- Departments of Biology and Entomology, Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, USA
| | - William A Nelson
- Department of Biology, Queen's University, Kingston, ON K7L3N6, Canada
| | - Andrew F Read
- Departments of Biology and Entomology, Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, USA.,Department of Fogarty, National Institutes of Health, Fogarty International Center, Bethesda, MD, USA
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15
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Cressler CE, Bengtson S, Nelson WA. Unexpected Nongenetic Individual Heterogeneity and Trait Covariance in Daphnia and Its Consequences for Ecological and Evolutionary Dynamics. Am Nat 2017; 190:E13-E27. [DOI: 10.1086/691779] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Nelson WA, Huang A. Discrimination and Patient-Centered Care. Organizational best-practice guidelines can provide ethical and legal guidance. Healthc Exec 2017; 32:54-56. [PMID: 29966053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
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Beck-Johnson LM, Nelson WA, Paaijmans KP, Read AF, Thomas MB, Bjørnstad ON. The importance of temperature fluctuations in understanding mosquito population dynamics and malaria risk. R Soc Open Sci 2017; 4:160969. [PMID: 28405386 PMCID: PMC5383843 DOI: 10.1098/rsos.160969] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2016] [Accepted: 02/06/2017] [Indexed: 05/16/2023]
Abstract
Temperature is a key environmental driver of Anopheles mosquito population dynamics; understanding its central role is important for these malaria vectors. Mosquito population responses to temperature fluctuations, though important across the life history, are poorly understood at a population level. We used stage-structured, temperature-dependent delay-differential equations to conduct a detailed exploration of the impacts of diurnal and annual temperature fluctuations on mosquito population dynamics. The model allows exploration of temperature-driven temporal changes in adult age structure, giving insights into the population's capacity to vector malaria parasites. Because of temperature-dependent shifts in age structure, the abundance of potentially infectious mosquitoes varies temporally, and does not necessarily mirror the dynamics of the total adult population. In addition to conducting the first comprehensive theoretical exploration of fluctuating temperatures on mosquito population dynamics, we analysed observed temperatures at four locations in Africa covering a range of environmental conditions. We found both temperature and precipitation are needed to explain the observed malaria season in these locations, enhancing our understanding of the drivers of malaria seasonality and how temporal disease risk may shift in response to temperature changes. This approach, tracking both mosquito abundance and age structure, may be a powerful tool for understanding current and future malaria risk.
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Affiliation(s)
- Lindsay M. Beck-Johnson
- Department of Biology, Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA, USA
- Author for correspondence: Lindsay M. Beck-Johnson e-mail:
| | - William A. Nelson
- Department of Biology, Queen’s University, Kingston, Ontario, Canada
| | - Krijn P. Paaijmans
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clinic, Universitat de Barcelona, Barcelona, Spain
| | - Andrew F. Read
- Department of Biology, Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA, USA
- Department of Entomology, Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA, USA
- Fogarty International Center, National Institutes of Health, Bethesda, MD, USA
| | - Matthew B. Thomas
- Department of Entomology, Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA, USA
| | - Ottar N. Bjørnstad
- Department of Biology, Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA, USA
- Department of Entomology, Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA, USA
- Fogarty International Center, National Institutes of Health, Bethesda, MD, USA
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Nelson WA. Rethinking the Traditional Ethics Committee. Healthc Exec 2017; 32:46-49. [PMID: 30280528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
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Westling CR, Walsh T, Nelson WA. Perceived Ethics Dilemmas Among Pioneer Accountable Care Organizations. J Healthc Manag 2017; 62:18-27. [PMID: 28319986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
This study of Pioneer accountable care organizations (ACOs) suggests that the ACO model is creating moral distress for physicians and business leaders in seven critical ways:Despite an overall sense of optimism associated with the ACO model, our research identified an underlying sense of moral distress at most sites. A clear opportunity exists for ACOs to use a more comprehensive, coordinated approach to proactively resolving ethical dilemmas while continuing the march toward risk-based contracts.
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Affiliation(s)
- Craig R Westling
- Craig R. Westling, DrPH, executive director of education, The Dartmouth Institute for Health Policy & Clinical Practice, Lebanon, New Hampshire; Thom Walsh, PhD, adjunct faculty, The Dartmouth Institute for Health Policy & Clinical Practice; and William A. Nelson, PhD, HFACHE, director, Health and Values Program, The Dartmouth Institute for Health Policy & Clinical Practice
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Goodman D, Ogrinc G, Davies L, Baker GR, Barnsteiner J, Foster TC, Gali K, Hilden J, Horwitz L, Kaplan HC, Leis J, Matulis JC, Michie S, Miltner R, Neily J, Nelson WA, Niedner M, Oliver B, Rutman L, Thomson R, Thor J. Explanation and elaboration of the SQUIRE (Standards for Quality Improvement Reporting Excellence) Guidelines, V.2.0: examples of SQUIRE elements in the healthcare improvement literature. BMJ Qual Saf 2016; 25:e7. [PMID: 27076505 PMCID: PMC5256235 DOI: 10.1136/bmjqs-2015-004480] [Citation(s) in RCA: 177] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 02/05/2016] [Accepted: 02/29/2016] [Indexed: 11/18/2022]
Abstract
Since its publication in 2008, SQUIRE (Standards for Quality Improvement Reporting Excellence) has contributed to the completeness and transparency of reporting of quality improvement work, providing guidance to authors and reviewers of reports on healthcare improvement work. In the interim, enormous growth has occurred in understanding factors that influence the success, and failure, of healthcare improvement efforts. Progress has been particularly strong in three areas: the understanding of the theoretical basis for improvement work; the impact of contextual factors on outcomes; and the development of methodologies for studying improvement work. Consequently, there is now a need to revise the original publication guidelines. To reflect the breadth of knowledge and experience in the field, we solicited input from a wide variety of authors, editors and improvement professionals during the guideline revision process. This Explanation and Elaboration document (E&E) is a companion to the revised SQUIRE guidelines, SQUIRE 2.0. The product of collaboration by an international and interprofessional group of authors, this document provides examples from the published literature, and an explanation of how each reflects the intent of a specific item in SQUIRE. The purpose of the guidelines is to assist authors in writing clearly, precisely and completely about systematic efforts to improve the quality, safety and value of healthcare services. Authors can explore the SQUIRE statement, this E&E and related documents in detail at http://www.squire-statement.org.
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Affiliation(s)
- Daisy Goodman
- Department of Obstetrics and Gynecology, Dartmouth Hitchcock Medical Center, Lebanon, New Hampshire, USA
| | - Greg Ogrinc
- Department of Education, Veterans Health Administration, White River Jct, Vermont, USA
| | - Louise Davies
- Department of Surgery, Veterans Health Administration, White River Jct, Vermont, USA
| | - G Ross Baker
- Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada
| | - Jane Barnsteiner
- Department of Nursing, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Tina C Foster
- Department of Obstetrics and Gynecology, Dartmouth Hitchcock Medical Center, Lebanon, New Hampshire, USA
| | - Kari Gali
- Department of Pediatrics, Cleveland Clinic Children's Hospital, Cleveland, Ohio, USA
| | - Joanne Hilden
- Department of Pediatrics, Colorado Children's Hospital, Aurora, Colorado, USA
| | - Leora Horwitz
- Division of Healthcare Delivery Science, New York University, New York, USA
| | - Heather C Kaplan
- Perinatal Institute and James M. Anderson Center for Health Systems Excellence, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - Jerome Leis
- Department of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - John C Matulis
- Department of Medicine, Dartmouth Hitchcock Medical Center, Lebanon, New Hampshire, USA
| | - Susan Michie
- Department of Clinical, Educational and Health Psychology, University College, London, UK
| | - Rebecca Miltner
- Department of Nursing, University of Alabama, Birmingham, Alabama, USA
| | - Julia Neily
- National Center for Patient Safety, Veterans Health Administration, White River Junction, NH USA
| | - William A Nelson
- Department of Psychiatry and Community and Family Medicine, Geisel School of Medicine, Hanover, New Hampshire, USA
| | - Matthew Niedner
- Department of Pediatrics, University of Michigan Medical Center, Ann Arbor, Michigan, USA
| | - Brant Oliver
- Department of Nursing, MGH Institute of Health Professions, Boston, Massachusetts, USA
| | - Lori Rutman
- Department of Pediatrics, Seattle Children's Hospital, Seattle, Washington, USA
| | - Richard Thomson
- Institute of Health and Society, Newcastle University, Newcastle upon Tyne, UK
| | - Johan Thor
- Jönköping Academy for Improvement of Health and Welfare, Jönköping University, Jönköping, Sweden
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Ohm JR, Teeple J, Nelson WA, Thomas MB, Read AF, Cator LJ. Fitness consequences of altered feeding behavior in immune-challenged mosquitoes. Parasit Vectors 2016; 9:113. [PMID: 26927687 PMCID: PMC4772315 DOI: 10.1186/s13071-016-1392-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 02/18/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria-infected mosquitoes have been reported to be more likely to take a blood meal when parasites are infectious than when non-infectious. This change in feeding behavior increases the likelihood of malaria transmission, and has been considered an example of parasite manipulation of host behavior. However, immune challenge with heat-killed Escherichia coli induces the same behavior, suggesting that altered feeding behavior may be driven by adaptive responses of hosts to cope with an immune response, rather than by parasite-specific factors. Here we tested the alternative hypothesis that down-regulated feeding behavior prior to infectiousness is a mosquito adaptation that increases fitness during infection. METHODS We measured the impact of immune challenge and blood feeding on the fitness of individual mosquitoes. After an initial blood meal, Anopheles stephensi Liston mosquitoes were experimentally challenged with heat-killed E. coli at a dose known to mimic the same temporal changes in mosquito feeding behavior as active malaria infection. We then tracked daily egg production and survivorship of females maintained on blood-feeding regimes that either mimicked down-regulated feeding behaviors observed during early malaria infection, or were fed on a four-day feeding cycle typically associated with uninfected mosquitoes. RESULTS Restricting access to blood meals enhanced mosquito survival but lowered lifetime reproduction. Immune-challenge did not impact either fitness component. Combining fecundity and survival to estimate the population-scale intrinsic rate of increase (r), we found that, contrary to the mosquito adaptation hypothesis, mosquito fitness decreased if blood feeding was delayed following an immune challenge. CONCLUSIONS Our data provide no support for the idea that malaria-induced suppression of blood feeding is an adaptation by mosquitoes to reduce the impact of immune challenge. Alternatively, the behavioral alterations may be neither host nor parasite adaptations, but rather a consequence of constraints imposed on feeding by activation of the mosquito immune response, i.e. non-adaptive illness-induced anorexia. Future work incorporating field conditions and different immune challenges could further clarify the effect of altered feeding on mosquito and parasite fitness.
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Affiliation(s)
- Johanna R Ohm
- Center for Infectious Disease Dynamics, Departments of Biology and Entomology, Pennsylvania State University, University Park, PA, USA.
| | - Janet Teeple
- Center for Infectious Disease Dynamics, Department of Entomology, Pennsylvania State University, University Park, PA, USA.
| | - William A Nelson
- Department of Biology, Queens University, Kingston, Ontario, Canada.
| | - Matthew B Thomas
- Center for Infectious Disease Dynamics, Department of Entomology, Pennsylvania State University, University Park, PA, USA.
| | - Andrew F Read
- Center for Infectious Disease Dynamics, Departments of Biology and Entomology, Pennsylvania State University, University Park, PA, USA.
| | - Lauren J Cator
- Grand Challenges in Ecosystems and Environment, Department of Life Sciences, Imperial College, Silwood Park Campus, London, UK.
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Abstract
The success of a health care institution-as defined by delivering high-quality, high-value care, positive patient outcomes, and financial solvency-is inextricably tied to the culture within that organization. The ability to achieve and sustain alignment between its mission, values, and everyday practices defines a positive organizational culture. An institution that has a diminished organizational culture, reflected in the failure to consistently align management and clinical decisions and practices with its mission and values, will struggle. The presence of misalignment or of ethics gaps affects the quality of care being delivered, the morale of the staff, and the organization's image in the community. Transforming an organizational culture will provide a foundation for success and a framework for daily ethics-grounded operations in any organization. However, building an ethics-grounded organization is a challenging process requiring strong organization leadership and planning. Using a case study, the authors provide a multiyear, continuous step-by-step strategy consisting of identifying ethics culture gaps, establishing an ethics taskforce, clarifying and prioritizing the problems, developing strategy for change, implementing the strategy, and evaluating outcomes. This process will assist organizations in aligning its actions with its mission and values, to find success on all fronts.
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Affiliation(s)
- William A Nelson
- Author Affiliations: Dartmouth Institute for Health Policy and Clinical Practice (Drs Nelson, Taylor, and Walsh), Dartmouth Center for Health Care Delivery Science (Drs Nelson and Walsh), Community and Family Medicine (Dr Nelson), and Master of Health Care Delivery Science Program (Dr Walsh), Geisel School of Medicine at Dartmouth, Hanover, New Hampshire
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Nelson WA. Making Ethical Decisions. A six-step process should guide ethical decision making in healthcare. Healthc Exec 2015; 30:46-48. [PMID: 26749991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
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Abstract
The ethical standard for informed consent is fostered within a shared decision-making (SDM) process. SDM has become a recognized and needed approach in health care decision-making. Based on an ethical foundation, the approach fosters the active engagement of patients, where the clinician presents evidence-based treatment information and options and openly elicits the patient's values and preferences. The SDM process is affected by the context in which the information exchange occurs. Rural settings are one context that impacts the delivery of health care and SDM. Rural health care is significantly influenced by economic, geographical and social characteristics. Several specific distinctive features influence rural health care decision-making-poverty, access to health care, isolation, over-lapping relationships, and a shared culture. The rural context creates challenges as well as fosters opportunities for the application of SDM as a natural dynamic within the rural provider-patient relationship. To fulfill the ethical requirements of informed consent through SDM, it is necessary to understand its inherent challenges and opportunities. Therefore, rural clinicians and ethicists need to be cognizant of the impact of the rural setting on SDM and use the insights as an opportunity to achieve SDM.
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Affiliation(s)
- William A Nelson
- Psychiatry, Community and Family Medicine, The Dartmouth Institute for Health Policy & Clinical Practice, Geisel School of Medicine at Dartmouth, Hanover, NH, USA,
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Abstract
Parasites often induce life-history changes in their hosts. In many cases, these infection-induced life-history changes are driven by changes in the pattern of energy allocation and utilization within the host. Because these processes will affect both host and parasite fitness, it can be challenging to determine who benefits from them. Determining the causes and consequences of infection-induced life-history changes requires the ability to experimentally manipulate life history and a framework for connecting life history to host and parasite fitness. Here, we combine a novel starvation manipulation with energy budget models to provide new insights into castration and gigantism in the Daphnia magna–Pasteuria ramosa host–parasite system. Our results show that starvation primarily affects investment in reproduction, and increasing starvation stress reduces gigantism and parasite fitness without affecting castration. These results are consistent with an energetic structure where the parasite uses growth energy as a resource. This finding gives us new understanding of the role of castration and gigantism in this system, and how life-history variation will affect infection outcome and epidemiological dynamics. The approach of combining targeted life-history manipulations with energy budget models can be adapted to understand life-history changes in other disease systems.
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Affiliation(s)
| | - William A Nelson
- Department of Biology, Queen's University, Kingston, Ontario, Canada
| | - Troy Day
- Department of Biology, Queen's University, Kingston, Ontario, Canada Department of Mathematics and Statistics, Queen's University, Kingston, Ontario, Canada
| | - Edward McCauley
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
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Goldson SL, Bourdôt GW, Brockerhoff EG, Byrom AE, Clout MN, McGlone MS, Nelson WA, Popay AJ, Suckling DM, Templeton MD. New Zealand pest management: current and future challenges. J R Soc N Z 2015. [DOI: 10.1080/03036758.2014.1000343] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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27
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Lahey T, Nelson WA. A proposed nationwide reporting system to satisfy the ethical obligation to prevent drug diversion-related transmission of hepatitis C in healthcare facilities. Clin Infect Dis 2015; 60:1816-20. [PMID: 25767254 DOI: 10.1093/cid/civ203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 03/04/2015] [Indexed: 11/14/2022] Open
Abstract
In 2012, dozens of patients of Exeter Hospital in New Hampshire contracted new hepatitis C infections that were tracked back to a cardiac technician who ultimately confessed to drug diversion. A multistate epidemiological investigation of hepatitis C cases occurring in multiple hospitals revealed that the technician had been fired from prior institutions due to similar drug diversion activity, about which Exeter Hospital had not been notified. In this article, we highlight the institutional ethical issues raised by this outbreak, and propose a national centralized reporting system to support institutional fulfillment of the ethical obligation to protect the health of patients by preventing such nosocomial outbreaks.
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Affiliation(s)
- Tim Lahey
- Geisel School of Medicine at Dartmouth Medical School, Hanover Dartmouth-Hitchcock Medical Center, Lebanon
| | - William A Nelson
- Geisel School of Medicine at Dartmouth Medical School, Hanover The Dartmouth Institute for Health Policy and Clinical Practice, Hanover, New Hampshire
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Nelson WA, Macauley RC. Balancing Issues of Medical Futility. Leaders must ensure policies exist and are followed. Healthc Exec 2015; 30:48-51. [PMID: 26738276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
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Nelson WA. Avoiding blinded healthcare leadership. Healthc Exec 2014; 29:46-49. [PMID: 25665299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
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Vasseur DA, Fox JW, Gonzalez A, Adrian R, Beisner BE, Helmus MR, Johnson C, Kratina P, Kremer C, de Mazancourt C, Miller E, Nelson WA, Paterson M, Rusak JA, Shurin JB, Steiner CF. Synchronous dynamics of zooplankton competitors prevail in temperate lake ecosystems. Proc Biol Sci 2014; 281:20140633. [PMID: 24966312 PMCID: PMC4083788 DOI: 10.1098/rspb.2014.0633] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Accepted: 06/04/2014] [Indexed: 11/12/2022] Open
Abstract
Although competing species are expected to exhibit compensatory dynamics (negative temporal covariation), empirical work has demonstrated that competitive communities often exhibit synchronous dynamics (positive temporal covariation). This has led to the suggestion that environmental forcing dominates species dynamics; however, synchronous and compensatory dynamics may appear at different length scales and/or at different times, making it challenging to identify their relative importance. We compiled 58 long-term datasets of zooplankton abundance in north-temperate and sub-tropical lakes and used wavelet analysis to quantify general patterns in the times and scales at which synchronous/compensatory dynamics dominated zooplankton communities in different regions and across the entire dataset. Synchronous dynamics were far more prevalent at all scales and times and were ubiquitous at the annual scale. Although we found compensatory dynamics in approximately 14% of all combinations of time period/scale/lake, there were no consistent scales or time periods during which compensatory dynamics were apparent across different regions. Our results suggest that the processes driving compensatory dynamics may be local in their extent, while those generating synchronous dynamics operate at much larger scales. This highlights an important gap in our understanding of the interaction between environmental and biotic forces that structure communities.
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Affiliation(s)
- David A Vasseur
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06520, USA
| | - Jeremy W Fox
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - Andrew Gonzalez
- Department of Biology, McGill University, Montreal, Quebec, Canada
| | - Rita Adrian
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany
| | - Beatrix E Beisner
- Department of Biological Sciences, University of Quebec at Montreal, Montreal, Quebec, Canada H3C 3P8
| | - Matthew R Helmus
- Department of Animal Ecology, Amsterdam Global Change Institute, Vrije Universiteit, Amsterdam 1081 HV, Netherlands
| | - Catherine Johnson
- Fisheries and Oceans Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, Canada B2Y 4A2
| | - Pavel Kratina
- School of Biological and Chemical Sciences, Queen Mary University of London, London E1 4NS, UK
| | - Colin Kremer
- W. K. Kellogg Biological Station and Department of Plant Biology, Michigan State University, Hickory Corners, MI 49060, USA Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Claire de Mazancourt
- Centre for Biodiversity Theory and Modelling, Station d'Ecologie Expérimentale du Centre National de la Recherche Scientifique à Moulis, Moulis 09200, France
| | - Elizabeth Miller
- W. K. Kellogg Biological Station and Department of Plant Biology, Michigan State University, Hickory Corners, MI 49060, USA Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA
| | - William A Nelson
- Department of Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6
| | - Michael Paterson
- IISD-Experimental Lakes Area, 161 Portage Ave East 6th Floor, Winnipeg, MB, Canada R3B 0Y4
| | - James A Rusak
- Ontario Ministry of the Environment, Dorset Environmental Science Centre, Dorset, Ontario, Canada P0A 1E0
| | - Jonathan B Shurin
- Section of Ecology, Behavior and Evolution, University of California-San Diego, 9500 Gilman Drive #0116, La Jolla, CA 92093, USA
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Nelson WA, Walsh T. Ensuring patient-centered care. Leaders must get involved and make it a priority. Healthc Exec 2014; 29:40-42. [PMID: 25672107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
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Nelson WA. Proposed ethical guidelines for quality improvement. Healthc Exec 2014; 29:52-55. [PMID: 24724316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
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Cressler CE, Nelson WA, Day T, McCauley E. Disentangling the interaction among host resources, the immune system and pathogens. Ecol Lett 2013; 17:284-93. [PMID: 24350974 PMCID: PMC4264941 DOI: 10.1111/ele.12229] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 08/28/2013] [Accepted: 11/05/2013] [Indexed: 12/25/2022]
Abstract
The interaction between the immune system and pathogens is often characterised as a predator–prey interaction. This characterisation ignores the fact that both require host resources to reproduce. Here, we propose novel theory that considers how these resource requirements can modify the interaction between the immune system and pathogens. We derive a series of models to describe the energetic interaction between the immune system and pathogens, from fully independent resources to direct competition for the same resource. We show that increasing within-host resource supply has qualitatively distinct effects under these different scenarios. In particular, we show the conditions for which pathogen load is expected to increase, decrease or even peak at intermediate resource supply. We survey the empirical literature and find evidence for all three patterns. These patterns are not explained by previous theory, suggesting that competition for host resources can have a strong influence on the outcome of disease.
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Affiliation(s)
- Clayton E Cressler
- Department of Biology, Queen's University, Kingston, ON, K7L 3N6, Canada
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Beck-Johnson LM, Nelson WA, Paaijmans KP, Read AF, Thomas MB, Bjørnstad ON. The effect of temperature on Anopheles mosquito population dynamics and the potential for malaria transmission. PLoS One 2013; 8:e79276. [PMID: 24244467 PMCID: PMC3828393 DOI: 10.1371/journal.pone.0079276] [Citation(s) in RCA: 163] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Accepted: 09/19/2013] [Indexed: 11/18/2022] Open
Abstract
The parasites that cause malaria depend on Anopheles mosquitoes for transmission; because of this, mosquito population dynamics are a key determinant of malaria risk. Development and survival rates of both the Anopheles mosquitoes and the Plasmodium parasites that cause malaria depend on temperature, making this a potential driver of mosquito population dynamics and malaria transmission. We developed a temperature-dependent, stage-structured delayed differential equation model to better understand how climate determines risk. Including the full mosquito life cycle in the model reveals that the mosquito population abundance is more sensitive to temperature than previously thought because it is strongly influenced by the dynamics of the juvenile mosquito stages whose vital rates are also temperature-dependent. Additionally, the model predicts a peak in abundance of mosquitoes old enough to vector malaria at more accurate temperatures than previous models. Our results point to the importance of incorporating detailed vector biology into models for predicting the risk for vector borne diseases.
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Affiliation(s)
- Lindsay M. Beck-Johnson
- Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- * E-mail:
| | - William A. Nelson
- Department of Biology, Queen's University, Kingston, Ontario, Canada
| | - Krijn P. Paaijmans
- Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Entomology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Andrew F. Read
- Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Entomology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Matthew B. Thomas
- Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Entomology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Ottar N. Bjørnstad
- Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Entomology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America
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Nelson WA, Lahey T. The ethics of mandatory flu shots. Balancing patient protection with healthcare worker autonomy is essential. Healthc Exec 2013; 28:42-46. [PMID: 24325037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Affiliation(s)
- William A Nelson
- Dartmouth Institute for Health Policy and Clinical Practice, Geisel School of Medicine at Dartmouth, USA.
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Ogrinc G, Nelson WA, Adams SM, O'Hara AE. An instrument to differentiate between clinical research and quality improvement. IRB 2013; 35:1-8. [PMID: 24350502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Affiliation(s)
| | - William A Nelson
- Darthmouth Institute for Health Policy and Clinical Practice, Geisel School of Medicine, Dartmouth, USA
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Abstract
Insects often undergo regular outbreaks in population density but identifying the causal mechanism for such outbreaks in any particular species has proven difficult. Here, we show that outbreak cycles in the tea tortrix Adoxophyes honmai can be explained by temperature-driven changes in system stability. Wavelet analysis of a 51-year time series spanning more than 200 outbreaks reveals a threshold in outbreak amplitude each spring when temperature exceeds 15°C and a secession of outbreaks each fall as temperature decreases. This is in close agreement with our independently parameterized mathematical model that predicts the system crosses a Hopf bifurcation from stability to sustained cycles as temperature increases. These results suggest that temperature can alter system stability and provide an explanation for generation cycles in multivoltine insects.
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Affiliation(s)
- William A Nelson
- Department of Biology, Queen's University, Kingston, Ontario, Canada.
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38
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Nelson WA. Necessary competencies for ethics committees. Skilled internal consultants vital to addressing ethics issues. Healthc Exec 2013; 28:46-48. [PMID: 24205562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Affiliation(s)
- William A Nelson
- Dartmouth Institute for Health Policy and Clinical Practice, Geisel School of Medicine, USA.
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Nelson WA. Addressing the second victims of medical error. Healthc Exec 2013; 28:56-59. [PMID: 23556387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Affiliation(s)
- William A Nelson
- Dartmouth Institute for Health Policy and Clinical Practice, Geisel School of Medicine, USA.
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Nelson WA. The imperative of a moral compass-driven healthcare organization. Front Health Serv Manage 2013; 30:39-45. [PMID: 24147380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Affiliation(s)
- William A Nelson
- The Dartmouth Institute for Health Policy and Clinical Practice, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
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41
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Affiliation(s)
- Adriana M. Olijnyk
- Department of Biology; Queen's University; Biosciences Complex, 116 Barrie St., Kingston ON K7L 3N6; Canada
| | - William A. Nelson
- Department of Biology; Queen's University; Biosciences Complex, 116 Barrie St., Kingston ON K7L 3N6; Canada
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42
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Nelson WA. The ethics of avoiding nonbeneficial healthcare: unnecessary treatment has both financial and moral implications. Healthc Exec 2012; 27:48-51. [PMID: 23173509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Affiliation(s)
- William A Nelson
- Dartmouth Institute for Health Policy and Clinical Practice, Geisel School of Medicine, USA.
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Abstract
SUMMARY
Retinal neurogenesis in fish facilitates cellular rearrangement throughout ontogeny, potentially allowing for optimization of the visual system to shifts in habitat and behaviour. To test this possibility, we studied the developmental trajectory of the photopic visual process in the Nile tilapia. We examined ontogenetic changes in lens transmission, photoreceptor sensitivity and post-receptoral sensitivity, and used these to estimate changes in cone pigment frequency and retinal circuitry. We observed an ontogenetic decrease in ultraviolet (UV) photoreceptor sensitivity, which resulted from a reduction in the SWS1 cone pigment frequency, and was associated with a reduction in lens transmission at UV wavelengths. Additionally, post-receptoral sensitivity to both UV and long wavelengths decreased with age, probably reflecting changes in photoreceptor sensitivity and retinal circuitry. This novel remodelling of retinal circuitry occurred following maturation of the visual system but prior to reaching adulthood, and thus may facilitate optimization of the visual system to the changing sensory demands. Interestingly, the changes in post-receptoral sensitivity to long wavelengths could not be predicted by the changes observed in lens transmission, cone pigment frequency or photoreceptor sensitivity. This finding emphasizes the importance of considering knowledge of visual sensitivity and retinal processing when studying visual adaptations and attempting to relate visual function to the natural environment. This study advances our understanding of ontogeny in visual systems and demonstrates that the association between different elements of the visual process can be explored effectively by examining visual function throughout ontogeny.
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Affiliation(s)
- Shai Sabbah
- Department of Biology, Queen's University, Kingston, ON, Canada, K7L 3N6
| | - Jonathan Hui
- Department of Biology, Queen's University, Kingston, ON, Canada, K7L 3N6
| | - Frances E. Hauser
- Department of Biology, Queen's University, Kingston, ON, Canada, K7L 3N6
| | - William A. Nelson
- Department of Biology, Queen's University, Kingston, ON, Canada, K7L 3N6
| | - Craig W. Hawryshyn
- Department of Biology, Queen's University, Kingston, ON, Canada, K7L 3N6
- Centre for Neuroscience Studies, Queen's University, Kingston, ON, Canada, K7L 3N6
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Nelson WA. Comparing ethics and compliance programs. Each is unique, but overlaps are key to clarifying organizational roles. Healthc Exec 2012; 27:46-49. [PMID: 22852201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Affiliation(s)
- William A Nelson
- Dartmouth Institute for Health Policy and Clinical Practice, Geisel School of Medicine, USA.
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Bell AS, Huijben S, Paaijmans KP, Sim DG, Chan BHK, Nelson WA, Read AF. Enhanced transmission of drug-resistant parasites to mosquitoes following drug treatment in rodent malaria. PLoS One 2012; 7:e37172. [PMID: 22701563 PMCID: PMC3368907 DOI: 10.1371/journal.pone.0037172] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Accepted: 04/17/2012] [Indexed: 11/19/2022] Open
Abstract
The evolution of drug resistant Plasmodium parasites is a major challenge to effective malaria control. In theory, competitive interactions between sensitive parasites and resistant parasites within infections are a major determinant of the rate at which parasite evolution undermines drug efficacy. Competitive suppression of resistant parasites in untreated hosts slows the spread of resistance; competitive release following treatment enhances it. Here we report that for the murine model Plasmodium chabaudi, co-infection with drug-sensitive parasites can prevent the transmission of initially rare resistant parasites to mosquitoes. Removal of drug-sensitive parasites following chemotherapy enabled resistant parasites to transmit to mosquitoes as successfully as sensitive parasites in the absence of treatment. We also show that the genetic composition of gametocyte populations in host venous blood accurately reflects the genetic composition of gametocytes taken up by mosquitoes. Our data demonstrate that, at least for this mouse model, aggressive chemotherapy leads to very effective transmission of highly resistant parasites that are present in an infection, the very parasites which undermine the long term efficacy of front-line drugs.
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Affiliation(s)
- Andrew S. Bell
- Center for Infectious Disease Dynamics, Departments of Biology and Entomology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Silvie Huijben
- Center for Infectious Disease Dynamics, Departments of Biology and Entomology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Krijn P. Paaijmans
- Center for Infectious Disease Dynamics, Departments of Biology and Entomology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Derek G. Sim
- Center for Infectious Disease Dynamics, Departments of Biology and Entomology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Brian H. K. Chan
- Center for Infectious Disease Dynamics, Departments of Biology and Entomology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - William A. Nelson
- Department of Biology, Queen’s University, Kingston, Ontario, Canada
| | - Andrew F. Read
- Center for Infectious Disease Dynamics, Departments of Biology and Entomology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America
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Nelson WA, Taylor EC. Ethics and advertising. Healthcare organizations must have an ethical framework in place for advertising. Healthc Exec 2012; 27:52-55. [PMID: 22439542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Affiliation(s)
- William A Nelson
- Dartmouth Institute for Health Policy and Clinical Practice, Dartmouth Medical School, USA.
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Yamanaka T, Nelson WA, Uchimura K, Bjørnstad ON. Generation separation in simple structured life cycles: models and 48 years of field data on a tea tortrix moth. Am Nat 2011; 179:95-109. [PMID: 22173463 DOI: 10.1086/663201] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Population cycles have fascinated ecologists since the early nineteenth century, and the dynamics of insect populations have been central to understanding the intrinsic and extrinsic biological processes responsible for these cycles. We analyzed an extraordinary long-term data set (every 5 days for 48 years) of a tea tortrix moth (Adoxophyes honmai) that exhibits two dominant cycles: an annual cycle with a conspicuous pattern of four or five single-generation cycles superimposed on it. General theory offers several candidate mechanisms for generation cycles. To evaluate these, we construct and parameterize a series of temperature-dependent, stage-structured models that include intraspecific competition, parasitism, mate-finding Allee effects, and adult senescence, all in the context of a seasonal environment. By comparing the observed dynamics with predictions from the models, we find that even weak larval competition in the presence of seasonal temperature forcing predicts the two cycles accurately. None of the other mechanisms predicts the dynamics. Detailed dissection of the results shows that a short reproductive life span and differential winter mortality among stages are the additional life-cycle characteristics that permit the sustained cycles. Our general modeling approach is applicable to a wide range of organisms with temperature-dependent life histories and is likely to prove particularly useful in temperate systems where insect pest outbreaks are both density and temperature dependent.
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Affiliation(s)
- Takehiko Yamanaka
- Biodiversity Division, National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604, Japan.
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Abstract
Malaria infections normally consist of more than one clonally replicating lineage. Within-host interactions between sensitive and resistant parasites can have profound effects on the evolution of drug resistance. Here, using the Plasmodium chabaudi mouse malaria model, we ask whether the costs and benefits of resistance are affected by the number of co-infecting strains competing with a resistant clone. We found strong competitive suppression of resistant parasites in untreated infections and marked competitive release following treatment. The magnitude of competitive suppression depended on competitor identity. However, there was no overall effect of the diversity of susceptible parasites on the extent of competitive suppression or release. If these findings generalize, then transmission intensity will impact on resistance evolution because of its effect on the frequency of mixed infections, not because of its effect on the distribution of clones per host. This would greatly simplify the computational problems of adequately capturing within-host ecology in models of drug resistance evolution in malaria.
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Affiliation(s)
- S Huijben
- Department of Biology, Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA 16802, USA.
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Nelson WA. Ethics: a foundation for quality. A strong ethical framework helps determine organizational sucess. Healthc Exec 2011; 26:46-49. [PMID: 22165302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Affiliation(s)
- William A Nelson
- Dartmouth Institute for Health Policy and Clinical Practice, Dartmouth Medical School.
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50
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Abstract
Within- and between-host disease processes occur on the same timescales, therefore changes in the within-host dynamics of parasites, resources, and immunity can interact with changes in the epidemiological dynamics to affect evolutionary outcomes. Consequently, studies of the evolution of disease life histories, that is, infection-age-specific patterns of transmission and virulence, have been constrained by the need for a mechanistic understanding of within-host disease dynamics. In a companion paper (Day et al. 2011), we develop a novel approach that quantifies the relevant within-host aspects of disease through genetic covariance functions. Here, we demonstrate how to apply this theory to data. Using two previously published datasets from rodent malaria infections, we show how to translate experimental measures into disease life-history traits, and how to quantify the covariance in these traits. Our results show how patterns of covariance can interact with epidemiological dynamics to affect evolutionary predictions for disease life history. We also find that the selective constraints on disease life-history evolution can vary qualitatively, and that "simple" virulence-transmission trade-offs that are often the subject of experimental investigation can be obscured by trade-offs within one trait alone. Finally, we highlight the type and quality of data required for future applications.
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Affiliation(s)
- Nicole Mideo
- Centre for Immunity, Infection, and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh, UK.
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