49 results on '"C. Buck"'
Search Results
2. A critical review of the application of polymer of low concern regulatory criteria to fluoropolymers II: Fluoroplastics and fluoroelastomers
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Stephen H. Korzeniowski, Robert C. Buck, Robin M. Newkold, Ahmed El kassmi, Evan Laganis, Yasuhiko Matsuoka, Bertrand Dinelli, Severine Beauchet, Frank Adamsky, Karl Weilandt, Vijay Kumar Soni, Deepak Kapoor, Priyanga Gunasekar, Marco Malvasi, Giulio Brinati, and Stefana Musio
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Geography, Planning and Development ,General Medicine ,General Environmental Science - Abstract
Fluoropolymers are a distinct class of per- and polyfluoroalkyl substances (PFAS), high molecular weight (MW) polymers with fluorine attached to their carbon-only backbone. Fluoropolymers possess a unique combination of properties and unmatched functional performance critical to the products and manufacturing processes they enable and are irreplaceable in many uses. Fluoropolymers have documented safety profiles; are thermally, biologically, and chemically stable, negligibly soluble in water, nonmobile, nonbioavailable, nonbioaccumulative, and nontoxic. Although fluoropolymers fit the PFAS structural definition, they have very different physical, chemical, environmental, and toxicological properties when compared with other PFAS. This study describes the composition, uses, performance properties, and functionalities of 14 fluoropolymers, including fluoroplastics and fluoroelastomers, and presents data to demonstrate that they satisfy the widely accepted polymer hazard assessment criteria to be considered polymers of low concern (PLC). The PLC criteria include physicochemical properties, such as molecular weight, which determine bioavailability and warn of potential hazard. Fluoropolymers are insoluble (e.g., water, octanol) solids too large to migrate into the cell membrane making them nonbioavailable, and therefore, of low concern from a human and environmental health standpoint. Further, the study results demonstrate that fluoropolymers are a distinct and different group of PFAS and should not be grouped with other PFAS for hazard assessment or regulatory purposes. When combined with an earlier publication by Henry et al., this study demonstrates that commercial fluoropolymers are available from the seven participating companies that meet the criteria to be considered PLC, which represent approximately 96% of the global commercial fluoropolymer market. Integr Environ Assess Manag 2022;00:1-29. © 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental ToxicologyChemistry (SETAC).
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- 2022
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3. Monitoring the dead as an ecosystem indicator
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Thomas M. Newsome, Philip S. Barton, William J. Ripple, Emma E. Spencer, Julia C. Buck, Jennifer M. DeBruyn, and Brandon T. Barton
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0106 biological sciences ,0303 health sciences ,Ecosystem health ,Biomass (ecology) ,decomposition ,Ecology ,Hypotheses ,Biology ,010603 evolutionary biology ,01 natural sciences ,Food web ,indicators ,03 medical and health sciences ,Abundance (ecology) ,Ecosystem management ,Ecosystem ,Carrion ,Terrestrial ecosystem ,carrion ,Ecology, Evolution, Behavior and Systematics ,QH540-549.5 ,030304 developmental biology ,Nature and Landscape Conservation ,ecosystem health - Abstract
Dead animal biomass (carrion) is present in all terrestrial ecosystems, and its consumption, decomposition, and dispersal can have measurable effects on vertebrates, invertebrates, microbes, parasites, plants, and soil. But despite the number of studies examining the influence of carrion on food webs, there has been no attempt to identify how general ecological processes around carrion might be used as an ecosystem indicator. We suggest that knowledge of scavenging and decomposition rates, scavenger diversity, abundance, and behavior around carrion, along with assessments of vegetation, soil, microbe, and parasite presence, can be used individually or in combination to understand food web dynamics. Monitoring carrion could also assist comparisons of ecosystem processes among terrestrial landscapes and biomes. Although there is outstanding research needed to fully integrate carrion ecology and monitoring into ecosystem management, we see great potential in using carrion as an ecosystem indicator of an intact and functional food web., We argue that information about the processes and organisms involved with the consumption and decomposition of dead animal matter (carrion) can provide insights into the broader health and integrity of ecosystems.
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- 2021
4. Conservation implications of disease control
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Georgia Titcomb, Sara B. Weinstein, Julia C. Buck, and Hillary S. Young
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medicine.medical_specialty ,Geography ,Ecology ,medicine ,Intensive care medicine ,Disease control ,Ecology, Evolution, Behavior and Systematics - Published
- 2020
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5. In situ liquid SIMS analysis of uranium oxide
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Edgar C. Buck, Xiao-Ying Yu, Jennifer Yao, and Zihua Zhu
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In situ ,Detection limit ,Materials science ,Radiochemistry ,chemistry.chemical_element ,Surfaces and Interfaces ,General Chemistry ,Nuclear material ,Uranium ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Secondary ion mass spectrometry ,chemistry.chemical_compound ,chemistry ,Materials Chemistry ,Uranium oxide - Published
- 2020
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6. Featured Cover
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Xiao‐Ying Yu, Jennifer Yao, Edgar C. Buck, and Zihua Zhu
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Materials Chemistry ,Surfaces and Interfaces ,General Chemistry ,Condensed Matter Physics ,Surfaces, Coatings and Films - Published
- 2020
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7. A critical review of the application of polymer of low concern and regulatory criteria to fluoropolymers
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Oscar Hernandez, L. William Buxton, Barbara J Henry, Jennifer Seed, Joseph P Carlin, Jon A Hammerschmidt, Heidelore Fiedler, and Robert C. Buck
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chemistry.chemical_classification ,Toxicity data ,Geography, Planning and Development ,02 engineering and technology ,General Medicine ,Polymer ,010501 environmental sciences ,021001 nanoscience & nanotechnology ,medicine.disease_cause ,01 natural sciences ,High molecular weight polymer ,chemistry.chemical_compound ,chemistry ,Environmental chemistry ,Toxicity ,Environmental toxicology ,medicine ,Perfluorooctanoic acid ,0210 nano-technology ,Chronic toxicity ,Genotoxicity ,0105 earth and related environmental sciences ,General Environmental Science - Abstract
Per- and polyfluoroalkyl substances (PFAS) are a group of fluorinated substances that are in the focus of researchers and regulators due to widespread presence in the environment and biota, including humans, of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). Fluoropolymers, high molecular weight polymers, have unique properties that constitute a distinct class within the PFAS group. Fluoropolymers have thermal, chemical, photochemical, hydrolytic, oxidative, and biological stability. They have negligible residual monomer and oligomer content and low to no leachables. Fluoropolymers are practically insoluble in water and not subject to long-range transport. With a molecular weight well over 100 000 Da, fluoropolymers cannot cross the cell membrane. Fluoropolymers are not bioavailable or bioaccumulative, as evidenced by toxicology studies on polytetrafluoroethylene (PTFE): acute and subchronic systemic toxicity, irritation, sensitization, local toxicity on implantation, cytotoxicity, in vitro and in vivo genotoxicity, hemolysis, complement activation, and thrombogenicity. Clinical studies of patients receiving permanently implanted PTFE cardiovascular medical devices demonstrate no chronic toxicity or carcinogenicity and no reproductive, developmental, or endocrine toxicity. This paper brings together fluoropolymer toxicity data, human clinical data, and physical, chemical, thermal, and biological data for review and assessment to show that fluoropolymers satisfy widely accepted assessment criteria to be considered as "polymers of low concern" (PLC). This review concludes that fluoropolymers are distinctly different from other polymeric and nonpolymeric PFAS and should be separated from them for hazard assessment or regulatory purposes. Grouping fluoropolymers with all classes of PFAS for "read across" or structure-activity relationship assessment is not scientifically appropriate. Integr Environ Assess Manag 2018;14:316-334. © 2018 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC).
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- 2018
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8. Phylogenetic patterns of trait and trait plasticity evolution: Insights from amphibian embryos
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Brian I. Crother, Patrick R. Stephens, Andrew R. Blaustein, Nick VandenBroek, Aaron B. Stoler, John I. Hammond, Lisa N. Barrow, Thomas M. Luhring, Emily Moriarty Lemmon, Greta M. Wengert, Jason T. Hoverman, James P. Collins, Julia E. Earl, Alexa Warwick, Oliver J. Hyman, Paul W. Bradley, Moses Michelson, Steven J. Price, Christopher M. Murray, Ann Chang, Andrew Sih, Rick A. Relyea, Stephanie S. Gervasi, Raymond D. Semlitsch, and Julia C. Buck
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0106 biological sciences ,Phylogenetic inertia ,Phenotypic plasticity ,Phylogenetic tree ,biology ,Hyla ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,010601 ecology ,Evolutionary biology ,Phylogenetic Pattern ,Phylogenetics ,Genetics ,Trait ,General Agricultural and Biological Sciences ,Clade ,Ecology, Evolution, Behavior and Systematics - Abstract
Environmental variation favors the evolution of phenotypic plasticity. For many species, we understand the costs and benefits of different phenotypes, but we lack a broad understanding of how plastic traits evolve across large clades. Using identical experiments conducted across North America, we examined prey responses to predator cues. We quantified five life-history traits and the magnitude of their plasticity for 23 amphibian species/populations (spanning three families and five genera) when exposed to no cues, crushed-egg cues, and predatory crayfish cues. Embryonic responses varied considerably among species and phylogenetic signal was common among the traits, whereas phylogenetic signal was rare for trait plasticities. Among trait-evolution models, the Ornstein-Uhlenbeck (OU) model provided the best fit or was essentially tied with Brownian motion. Using the best fitting model, evolutionary rates for plasticities were higher than traits for three life-history traits and lower for two. These data suggest that the evolution of life-history traits in amphibian embryos is more constrained by a species' position in the phylogeny than is the evolution of life history plasticities. The fact that an OU model of trait evolution was often a good fit to patterns of trait variation may indicate adaptive optima for traits and their plasticities.
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- 2018
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9. Prospective Review of Mesenchymal Stem Cells Differentiation into Osteoblasts
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Meghan E Wandtke, Nabil A. Ebraheim, Priyanka Garg, Amy C Buck, Jiayong Liu, and Matthew M. Mazur
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0301 basic medicine ,Pathology ,medicine.medical_specialty ,Mesenchymal stem cell ,Clinical uses of mesenchymal stem cells ,Osteoblast ,Bone healing ,Biology ,Bone morphogenetic protein ,03 medical and health sciences ,030104 developmental biology ,medicine.anatomical_structure ,medicine ,Cancer research ,Orthopedics and Sports Medicine ,Surgery ,Bone marrow ,Bone regeneration ,Stem cell transplantation for articular cartilage repair - Abstract
Stem cell research has been a popular topic in the past few decades. This review aims to discuss factors that help regulate, induce, and enhance mesenchymal stem cell (MSC) differentiation into osteoblasts for bone regeneration. The factors analyzed include bone morphogenic protein (BMP), transforming growth factor β (TGF-β), stromal cell-derived factor 1 (SDF-1), insulin-like growth factor type 1 (IGF-1), histone demethylase JMJD3, cyclin dependent kinase 1 (CDK1), fucoidan, Runx2 transcription factor, and TAZ transcriptional coactivator. Methods promoting bone healing are also evaluated in this review that have shown promise in previous studies. Methods tested using animal models include low intensity pulsed ultrasound (LIPUS) with MSC, micro motion, AMD3100 injections, BMP delivery, MSC transplantation, tissue engineering utilizing scaffolds, anti-IL-20 monoclonal antibody, low dose photodynamic therapy, and bone marrow stromal cell transplants. Human clinical trial methods analyzed include osteoblast injections, bone marrow grafts, bone marrow and platelet rich plasma transplantation, tissue engineering using scaffolds, and recombinant human BMP-2. These methods have been shown to promote and accelerate new bone formation. These various methods for enhanced bone regeneration have the potential to be used, following further research, in clinical practice.
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- 2017
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10. Formation of Technetium Salts in Hanford Low-Activity Waste Glass
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Chuck Z. Soderquist, Albert A. Kruger, Edgar C. Buck, Mike J. Schweiger, and John S. McCloy
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chemistry.chemical_classification ,Supersaturation ,Materials science ,Volatilisation ,Pertechnetate ,Scanning electron microscope ,Potassium ,chemistry.chemical_element ,Salt (chemistry) ,02 engineering and technology ,021001 nanoscience & nanotechnology ,010403 inorganic & nuclear chemistry ,Technetium ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Phase (matter) ,Materials Chemistry ,Ceramics and Composites ,0210 nano-technology ,Nuclear chemistry - Abstract
The distribution and physical form of technetium in a Hanford low-activity waste (LAW) glass was examined with scanning electron microscopy (SEM) and X-ray diffraction (XRD). A simulated Hanford LAW glass was spiked with varying amounts of potassium pertechnetate and melted at 1000°C. The glass was melted in a sealed quartz ampoule with the air pumped out, so that volatile material could leave the glass but would not be lost from the system. Previous studies have shown that technetium remains in the glass up to about 2000 ppm, but rises to the top of the melt as a separate salt phase above this concentration. Examination by SEM shows that crystals of technetium compounds appear to grow out of the hot glass, which implies that the hot glass was supersaturated in technetium salts. Some of the technetium compound crystals had apparently melted, but other crystals had obviously not melted and must have formed after the glass had partially cooled. The technetium compounds in the salt layer are KTcO4 and NaTcO4, according to SEM and XRD. No TcO2 was found in the salt phase, even though Tc(IV) has been previously reported in the glass.
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- 2016
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11. Effects of nutrient supplementation on host‐pathogen dynamics of the amphibian chytrid fungus: a community approach
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Jason R. Rohr, Julia C. Buck, and Andrew R. Blaustein
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0106 biological sciences ,Amphibian ,Larva ,biology ,Ecology ,010604 marine biology & hydrobiology ,Aquatic ecosystem ,media_common.quotation_subject ,Aquatic Science ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Tadpole ,Article ,Food web ,13. Climate action ,biology.animal ,14. Life underwater ,Metamorphosis ,Trophic cascade ,Eutrophication ,media_common - Abstract
Anthropogenic stressors may influence hosts and their pathogens directly or may alter host–pathogen dynamics indirectly through interactions with other species. For example, in aquatic ecosystems, eutrophication may be associated with increased or decreased disease risk. Conversely, pathogens can influence community structure and function and are increasingly recognised as important members of the ecological communities in which they exist.In outdoor mesocosms, we experimentally manipulated nutrients (nitrogen and phosphorus) and the presence of a fungal pathogen, Batrachochytrium dendrobatidis (Bd), and examined the effects on Bd abundance on larval amphibian hosts (Pseudacris regilla: Hylidae), amphibian traits and community dynamics. We predicted that resource supplementation would mitigate negative effects of Bd on tadpole growth and development and that indirect effects of treatments would propagate through the community.Nutrient additions caused changes in algal growth, which benefitted tadpoles through increased mass, development and survival. Bd-exposed tadpoles metamorphosed sooner than unexposed individuals, but their mass at metamorphosis was not affected by Bd exposure. We detected additive rather than interactive effects of nutrient supplementation and Bd in this experiment.Nutrient supplementation was not a significant predictor of infection load of larval amphibians. However, a structural equation model revealed that resource supplementation and exposure of amphibians to Bd altered the structure of the aquatic community. This is the first demonstration that sublethal effects of Bd on amphibians can alter aquatic community dynamics.
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- 2015
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12. Identification of Uranyl Minerals Using Oxygen K-Edge X-Ray Absorption Spectroscopy
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Edgar C. Buck, Gregory C. Eiden, Mark E. Bowden, C. Tom Resch, Steven J. Smith, Jesse Ward, Andrew M. Duffin, and Bruce K. McNamara
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X-ray absorption spectroscopy ,Chemistry ,Mineralogy ,Geology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Uranyl ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,K-edge ,Geochemistry and Petrology ,Physical chemistry ,0210 nano-technology - Abstract
Although most of the world's uranium exists as pitchblende or uraninite, this mineral can be weathered to a great variety of secondary uranium minerals, most containing the uranyl cation. Anthropogenic uranium compounds can also react in the environment, leading to spatial–chemical alterations that could be useful for nuclear forensics analyses. Soft X-ray absorption spectroscopy (XAS) has the advantages of being non-destructive, element-specific and sensitive to electronic and physical structure. The soft X-ray probe can also be focused to a spot size on the order of tens of nanometres, providing chemical information with high spatial resolution. However, before XAS can be applied at high spatial resolution, it is necessary to find spectroscopic signatures for a variety of uranium compounds in the soft X-ray spectral region. To that end, we collected the near edge X-ray absorption fine structure (NEXAFS) spectra of a variety of common uranyl-bearing minerals, including uranyl carbonates, oxyhydroxides, phosphates and silicates. We find that uranyl compounds can be distinguished by class (carbonate, oxyhydroxide, phosphate or silicate) based on their oxygen K-edge absorption spectra. This work establishes a database of reference spectra for future spatially resolved analyses. We proceed to show scanning X-ray transmission microscopy (STXM) data from a schoepite particle in the presence of an unknown contaminant. Bien que la plupart de l'uranium mondial soit contenu dans la pechblende ou l'uraninite, ces phases minerales peuvent etre alterees en une grande variete de mineraux uraniferes secondaires, la plupart contenant le cation uranyle. Les composes d'uranium anthropogeniques peuvent egalement reagir dans l'environnement, entrainant des alterations spatio-chimiques qui pourraient etre utiles pour les analyses dans le domaine de l'expertise scientifique nucleaire. La spectroscopie d'absorption des rayons X mous (XAS) presente l'avantage d'etre non destructive, specifique a l'element, et sensible a la structure physique et electronique. La sonde de rayons X mous peut egalement etre focalise pour atteindre une taille de spot de l'ordre de quelques dizaines de nanometres, fournissant ainsi des informations chimiques a haute resolution spatiale. Toutefois, avant que la XAS puisse etre appliquee a haute resolution spatiale, il est necessaire de trouver des signatures spectroscopiques pour une variete de composes d'uranium dans la region spectrale des rayons X mous. A cette fin, nous avons collecte les spectres de structure pres du front d'absorption des rayons X (NEXAFS) d'une variete de mineraux communs contenant des cations uranyles, y compris des carbonates d'uranyle, des oxyhydroxydes, des phosphates et des silicates. Nous montrons que les composes d'uranyle peuvent etre distingues par classe (carbonate, oxyhydroxyde, phosphate ou silicate) en fonction de leur spectre d'absorption des rayons X pres du seuil K de l'oxygene. Ce travail etablit une base de donnees de spectres de reference pour les futures analyses spatialement resolues. Nous presentons des donnees de microscopie a balayage par transmission des rayons X (STXM) d'une particule de schoepite en presence d'un contaminant inconnu.
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- 2015
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13. Larval exposure to predator cues alters immune function and response to a fungal pathogen in post-metamorphic wood frogs
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Rick A. Relyea, Stephanie S. Gervasi, Mark E. Bier, Andrew R. Blaustein, John Hempel, Laura K. Reinert, Julia C. Buck, Maya L. Groner, and Louise A. Rollins-Smith
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Amphibian ,Insecticides ,Larva ,Chytridiomycota ,Behavior, Animal ,Ranidae ,Ecology ,biology ,media_common.quotation_subject ,Lithobates ,Fungi ,Metamorphosis, Biological ,biology.organism_classification ,Temporin ,biology.animal ,Malathion ,Animals ,Chytridiomycosis ,Metamorphosis ,Predator ,media_common - Abstract
For the past several decades, amphibian populations have been decreasing around the globe at an unprecedented rate. Batrachochytrium dendrobatidis (Bd), the fungal pathogen that causes chytridiomycosis in amphibians, is contributing to amphibian declines. Natural and anthropogenic environmental factors are hypothesized to contribute to these declines by reducing the immunocompetence of amphibian hosts, making them more susceptible to infection. Antimicrobial peptides (AMPs) produced in the granular glands of a frog's skin are thought to be a key defense against Bd infection. These peptides may be a critical immune defense during metamorphosis because many acquired immune functions are suppressed during this time. To test if stressors alter AMP production and survival of frogs exposed to Bd, we exposed wood frog (Lithobates sylvaticus) tadpoles to the presence or absence of dragonfly predator cues crossed with a single exposure to three nominal concentrations of the insecticide malathion (0, 10, or 100 parts per billion (ppb)). We then exposed a subset of post-metamorphic frogs to the presence or absence of Bd zoospores and measured frog survival. Although predator cues and malathion had no effect on survival or size at metamorphosis, predator cues increased the time to metamorphosis by 1.5 days and caused a trend of a 20% decrease in hydrophobic skin peptides. Despite this decrease in peptides determined shortly after metamorphosis, previous exposure to predator cues increased survival in both Bd-exposed and unexposed frogs several weeks after metamorpho- sis. These results suggest that exposing tadpoles to predator cues confers fitness benefits later in life.
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- 2013
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14. The effects of multiple stressors on wetland communities: pesticides, pathogens and competing amphibians
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Julia C. Buck, Andrew R. Blaustein, Rick A. Relyea, and Erin A. Scheessele
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Amphibian ,education.field_of_study ,Larva ,biology ,Ecology ,media_common.quotation_subject ,Population ,Interspecific competition ,Aquatic Science ,biology.organism_classification ,Pseudacris regilla ,Competition (biology) ,Intraspecific competition ,biology.animal ,Periphyton ,education ,media_common - Abstract
SUMMARY 1. Anthropogenic effects have propelled us into what many have described as the sixth mass extinction, and amphibians are among the most affected groups. The causes of global amphibian population declines and extinctions are varied, complex and context-dependent and may involve multiple stressors. However, experimental studies examining multiple factors contributing to amphibian population declines are rare. 2. Using outdoor mesocosms containing zooplankton, phytoplankton, periphyton and tadpoles, we conducted a 2 · 2 · 3 factorial experiment that examined the separate and combined effects of an insecticide and the fungal pathogen Batrachochytrium dendrobatidis (Bd) on three different assemblages of larval pacific treefrogs (Pseudacris regilla) and Cascades frogs (Rana cascadae). 3. Larval amphibian growth and development were affected by carbaryl and the amphibian assemblage treatment, but only minimally by Bd. Carbaryl delayed metamorphosis in both amphibian species and increased the growth rate of P. regilla. Carbaryl also reduced cladoceran abundance, which, in turn, had positive effects on phytoplankton abundance but no effect on periphyton biomass. Substituting 20 intraspecific competitors with 20 interspecific competitors decreased the larval period but not the growth rate of P. regilla. In contrast, substituting 20 intraspecific competitors with 20 interspecific competitors had no effect on R. cascadae. Results of real-time quantitative polymerase chain reaction (qPCR) analysis confirmed infection of Bd-exposed animals, but exposure to Bd had no effects on either species in univariate analyses, although it had significant or nearly significant effects in several multivariate analyses. In short, we found no interactive effects among the treatments on amphibian growth and development. 4. We encourage future research on the interactive effects of pesticides and pathogens on amphibian communities.
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- 2011
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15. The complexity of amphibian population declines: understanding the role of cofactors in driving amphibian losses
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Andrew R. Blaustein, Julia C. Buck, Lee B. Kats, Rick A. Relyea, Stephanie S. Gervasi, Barbara A. Han, and Pieter T. J. Johnson
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Amphibian ,education.field_of_study ,animal structures ,Extinction ,Ecology ,General Neuroscience ,Population ,Endangered species ,Biodiversity ,Context (language use) ,Biology ,General Biochemistry, Genetics and Molecular Biology ,Invasive species ,History and Philosophy of Science ,Evolutionary trap ,biology.animal ,embryonic structures ,education - Abstract
Population losses and extinctions of species are occurring at unprecedented rates, as exemplified by declines and extinctions of amphibians worldwide. However, studies of amphibian population declines generally do not address the complexity of the phenomenon or its implications for ecological communities, focusing instead on single factors affecting particular amphibian species. We argue that the causes for amphibian population declines are complex; may differ among species, populations, and life stages within a population; and are context dependent with multiple stressors interacting to drive declines. Because amphibians are key components of communities, we emphasize the importance of investigating amphibian declines at the community level. Selection pressures over evolutionary time have molded amphibian life history characteristics, such that they may remain static even in the face of strong, recent human-induced selection pressures.
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- 2011
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16. Anion‐Mediated Effects on the Size and Mechanical Properties of Enzymatically Crosslinked Suckerin Hydrogels
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Rajesh R. Naik, Patrick B. Dennis, Chelsea C. Buck, Joseph M. Slocik, Maneesh K. Gupta, Marquise G. Crosby, Peter A. Mirau, Kristen K. Comfort, Marcus T. Grant, and Kellie A. Becknell
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Kosmotropic ,Polymers and Plastics ,Chemistry ,Decapodiformes ,Hydrogels ,Bioengineering ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Charge screening ,0104 chemical sciences ,Ion ,Biomaterials ,Salt solution ,Chemical engineering ,Self-healing hydrogels ,Materials Chemistry ,Animals ,Protein Isoforms ,Stress, Mechanical ,Fibroins ,0210 nano-technology ,Biotechnology - Abstract
The suckerin family of proteins, identified from the squid sucker ring teeth assembly, offers unique mechanical properties and potential advantages over other natural biomaterials. In this study, a small suckerin isoform, suckerin-12, is used to create enzymatically crosslinked, macro-scale hydrogels. Upon exposure to specific salt conditions, suckerin-12 hydrogels contracted into a condensed state where mechanical properties are found to be modulated by the salt anion present. The rate of contraction is found to correlate well with the kosmotropic arm of the Hofmeister anion series. However, the observed changes in hydrogel mechanical properties are better explained by the ability of the salt to neutralize charges in suckerin-12 by deprotonization or charge screening. Thus, by altering the anions in the condensing salt solution, it is possible to tune the mechanical properties of suckerin-12 hydrogels. The potential for suckerins to add new properties to materials based on naturally-derived proteins is highlighted.
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- 2018
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17. Complete multinuclear magnetic resonance characterization of a set of polyfluorinated acids and alcohols
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Robert C. Buck and Alexander A. Marchione
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Homologous series ,chemistry.chemical_compound ,Nuclear magnetic resonance ,Stereochemistry ,Chemistry ,Molecule ,General Materials Science ,General Chemistry ,Carbon-13 NMR ,Two-dimensional nuclear magnetic resonance spectroscopy ,Heteronuclear single quantum coherence spectroscopy ,Characterization (materials science) - Abstract
A complete 1H, 19F, and 13C NMR assignment of a homologous series of polyfluorinated acids and alcohols is reported. These assignments were obtained chiefly through single and multiple-bond 1H–13C and 19F–13C correlation experiments (HSQC, HMBC). 19F NOESY experiments were required for assignment of two compounds with diastereotopic 19F nuclei in the CF2chain of the molecule. Copyright © 2008 John Wiley & Sons, Ltd.
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- 2008
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18. The effects of monophenol chain terminators on the structure–property relationships of controlled epoxy networks
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Lisa Allen, Anamari Laboy‐Bollinger, K. James Hrovat, James C. Buck, James A. Rabon, Carol L. O'connell, Nikhil E. Verghese, and Maurice J. Marks
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Polymers and Plastics ,Chemistry ,Thermodynamics ,Concentration effect ,Dynamic mechanical analysis ,Epoxy ,Condensed Matter Physics ,Mole fraction ,Thermal expansion ,visual_art ,Polymer chemistry ,Materials Chemistry ,visual_art.visual_art_medium ,Thermomechanical analysis ,Thermal stability ,Physical and Theoretical Chemistry ,Glass transition - Abstract
Five families of new controlled epoxy thermosets (CENs) using three monophenol chain terminators were prepared to study systematic changes in the structure and amount of the monophenol and the initial molecular weight between crosslinks (M c,i ) on the properties of epoxy thermosets. Glass transition temperature (T g ) decreases with monophenol mole fraction (χ) in proportion to both the concentration and flexibility of the chain terminator. Distinct serial relations for T g depression were observed for the three M c,i families. Dynamic mechanical analysis (DMA) shows significant perturbations of the relaxation behavior with added terminator as evidenced by decrease in peak tan δ and in post T g damping. The rubbery coefficients of thermal expansion (CTE) increases with monophenol concentration only at χ> 0.05 and shows distinct curvature versus temperature, but is largely invariant with monophenol flexibility. The thermal stability of terminated CENs decreases only slightly with χ and little difference was found with monophenol structure. Most surprisingly, fracture toughness decreases markedly and discontinuously with χ c depending on M c,i . The values of the critical monophenol concentration at which fracture toughness markedly decreases (χ c ) are inversely proportional to M c,i but are independent of monophenol flexibility. No correlation of χ c with any of the calculated network structure parameters was apparent.
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- 2008
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19. Role of Androgens in the Phenology of Male Arctic Ground Squirrels
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Brian M. Barnes, Melanie M. Richter, and C Buck
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Arctic ,Ecology ,Phenology ,Genetics ,Biology ,Molecular Biology ,Biochemistry ,Biotechnology - Published
- 2015
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20. Dopamine D2 receptor stimulation of mitogen-activated protein kinases mediated by cell type-dependent transactivation of receptor tyrosine kinases
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Tara A. Macey, Kim A. Neve, David C. Buck, Rui Yang, and Chunhe Wang
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Transcriptional Activation ,Quinpirole ,Blotting, Western ,Genetic Vectors ,Transfection ,Tritium ,Biochemistry ,Tropomyosin receptor kinase C ,Piperazines ,Receptor tyrosine kinase ,Indole Alkaloids ,Rats, Sprague-Dawley ,Neuroblastoma ,Radioligand Assay ,Cellular and Molecular Neuroscience ,Animals ,Humans ,Simplexvirus ,Drug Interactions ,5-HT5A receptor ,Enzyme Inhibitors ,Extracellular Signal-Regulated MAP Kinases ,Cells, Cultured ,Protease-activated receptor 2 ,Platelet-Derived Growth Factor ,Microscopy, Confocal ,Dose-Response Relationship, Drug ,Epidermal Growth Factor ,biology ,Receptors, Dopamine D2 ,Receptor transactivation ,Receptor Protein-Tyrosine Kinases ,Tyrphostins ,Rats ,Cell biology ,Animals, Newborn ,Gene Expression Regulation ,Spiperone ,Dopamine Agonists ,ROR1 ,Quinazolines ,biology.protein ,Cancer research ,Dopamine Antagonists ,Estrogen-related receptor gamma ,Tyrosine kinase - Abstract
Dopamine D2 receptor activation of extracellular signal-regulated kinases (ERKs) in non-neuronal human embryonic kidney 293 cells was dependent on transactivation of the platelet-derived growth factor (PDGF) receptor, as demonstrated by the effect of the PDGF receptor inhibitors tyrphostin A9 and AG 370 on quinpirole-induced phosphorylation of ERKs and by quinpirole-induced tyrosine phosphorylation of the PDGF receptor. In contrast, ectopically expressed D2 receptor or endogenous D2-like receptor activation of ERKs in NS20Y neuroblastoma cells, which express little or no PDGF receptor, or in rat neostriatal neurons was largely dependent on transactivation of the epidermal growth factor (EGF) receptor, as demonstrated using the EGF receptor inhibitor AG 1478 and by quinpirole-induced phosphorylation of the EGF receptor. The D2 receptor agonist quinpirole enhanced the coprecipitation of D2 and EGF receptors in NS20Y cells, suggesting that D2 receptor activation induced the formation of a macromolecular signaling complex that includes both receptors. Transactivation of the EGF receptor also involved the activity of a matrix metalloproteinase. Thus, although D2 receptor stimulation of ERKs in both cell lines was decreased by inhibitors of ERK kinase, Src-family protein tyrosine kinases, and serine/threonine protein kinases, D2-like receptors activated ERKs via transactivation of the EGF receptor in NS20Y neuroblastoma cells and rat embryonic neostriatal neurons, but via transactivation of the PDGF receptor in 293 cells.
- Published
- 2005
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- View/download PDF
21. Tissue-engineered bone biomimetic to regenerate calvarial critical-sized defects in athymic rats
- Author
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Shelley R. Winn, David C. Buck, John M. Schmitt, David W. Grainger, Yunhua Hu, and Jeffrey O. Hollinger
- Subjects
Chemistry ,Regeneration (biology) ,Biomedical Engineering ,Calvaria ,Osteoblast ,Bone morphogenetic protein ,Biomaterials ,Andrology ,stomatognathic diseases ,medicine.anatomical_structure ,Precursor cell ,medicine ,Tissue engineered bone ,Bone regeneration ,Type I collagen ,Biomedical engineering - Abstract
A tissue-engineered bone biomimetic device was developed to regenerate calvaria critical-sized defects (CSDs) in athymic rats. Well-documented evidence clearly confirms that left untreated, CSDs will not spontaneously regenerate bone. To accomplish regeneration, four candidate treatments were assessed: porous poly(D,L-lactide) and type I collagen (PLC), PLC and human osteoblast precursor cells (OPCs) at 2 × 105 (PLC/OPCs), PLC and 50 μg of recombinant human bone morphogenetic protein-2 (PLC/rhBMP-2), and PLC/OPCs/rhBMP-2 (the bone biomimetic device). The hypotheses for this study were PLC/OPCs/rhBMP-2 would promote more new bone formation in CSDs than the other treatments and the amount of bone formation would be time dependent. To test the hypotheses, outcomes from treatments were measured at 2 and 4 weeks postoperatively by radiomorphometry for percent radiopacity and by histomorphometry for square millimeters of new bone formation. Data were analyzed by analysis of variance and Fisher's protected least significant difference for multiple comparisons with p ⩽ 0.05. At 2 and 4 weeks, radiomorphometric data revealed PLC/rhBMP-2 and PLC/OPCs/rhBMP-2 promoted significantly more radiopacity than either PLC or PLC/OPCs. Histomorphometry data at 2 and 4 weeks indicated significantly more new bone formation for PLC/rhBMP-2, PLC/OPCs/rhBMP-2, and PLC/OPCs compared to PLC. By 4 weeks, PLC/OPCs/rhBMP-2 and PLC/rhBMP-2 had regenerated the CSDs with more new bone than the other treatments; the quantity of bone at 4 weeks for these treatments was greater than at 2 weeks. © 1999 John Wiley & Sons, Inc. J Biomed Mater Res, 45, 414–421, 1999.
- Published
- 1999
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- View/download PDF
22. Assessment of an experimental bone wax polymer plus TGF-?1 implanted into calvarial defects
- Author
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David C. Buck, John M. Schmitt, Douglas D. Buechter, Chris Christoforou, Jeffrey O. Hollinger, Steven L. Bennett, Walter Skalla, and Elliott A. Gruskin
- Subjects
Materials science ,Biocompatibility ,Bone wax ,Radiodensity ,Biomedical Engineering ,Biomaterial ,Histology ,Calvaria ,Biodegradable polymer ,Biomaterials ,medicine.anatomical_structure ,Hemostasis ,medicine ,Biomedical engineering - Abstract
The study reported describes an experimental biodegradable polymer ceramic composite with wax-like handling properties that was combined with 2.0 μg of recombinant human transforming growth factor beta (rhTGF-β1). The polymer/rhTGF-β1 combination was introduced into standard-sized calvarial defects in rabbits to evaluate biodegradability, biocompatibility, hemostasis control, and bone promotion. The experimental wound model was a standard-sized circular calvarial defect 8 mm in diameter. The experimental design included 24 skeletally mature New Zealand white rabbits divided evenly between two time periods (6 and 12 weeks) and among three experimental treatments (untreated defects and defects treated with polymer with or without rhTGF-β1). Evaluations consisted of clinical examinations, standardized radiography, radiomorphometry, as well as histology and histomorphometry. Data were analyzed by an Analysis of Variance (ANOVA) and Fisher's Protected Least Significant Difference test at each time period (level of significance p⩽ 0.05). Radiomorphometry data indicated that standard-sized defects treated with the wax-like polymer alone and the polymer plus 2.0 μg of TGF-β1 were significantly more radiopaque than control sites at both 6 and 12 weeks. Histomorphometric data revealed the amount of new bone was significantly greater at 6 weeks in the polymer plus 2.0 μg of TGF-β1 and in the control group than in the polymer alone. Moreover, at 12 weeks, there was significantly more new bone in the control than in either the polymer alone or the polymer plus 2.0 μg of TGF-β1. We speculate the incomplete biodegradation of the polymer ceramic composite contributed to the radiopacity and may have retarded osseous regeneration. It is important that the bone wax-like polymer material was biocompatible and acted as a hemostatic agent. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 41, 584–592, 1998.
- Published
- 1998
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- View/download PDF
23. Recombinant human bone morphogenetic protein-2 and collagen for bone regeneration
- Author
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Jeffrey O. Hollinger, Robert Shannon, David C. Buck, John M. Schmitt, Seong Pil Joh, John M. Wozney, and H. Daniel Zegzula
- Subjects
Pathology ,medicine.medical_specialty ,Lagomorpha ,biology ,business.industry ,Radiodensity ,Biomedical Engineering ,Human bone ,Histology ,Bone morphogenetic protein ,biology.organism_classification ,law.invention ,Biomaterials ,law ,Orthopedic surgery ,Recombinant DNA ,Medicine ,Bone regeneration ,business - Abstract
The study reported describes a combination of recombinant human bone morphogenetic protein-2 (rhBMP-2) and collagen (C) to regenerate bone. Unilateral critical-sized defects (CSDs) were prepared in radii of 32 skeletally mature New Zealand white rabbits. Rabbits were divided evenly among four treatments: autograft, absorbable C (Helistat), 35 microg of rhBMP-2 combined with absorbable C (rhBMP-2/C), and untreated CSDs. The two euthanasia periods were 4 and 8 weeks. Radiographs were taken the day of surgery, every 2 weeks, and at term and the percent of radiopacity was measured. Data analysis revealed a time-dependent increase in the percent radiopacity with rhBMP-2/C. Histological examination revealed the rhBMP-2/C treatment regenerated osseous contour by 8 weeks. According to quantitative histomorphometry, the CSD and C groups had significantly less new bone than either autograft or rhBMP-2/C (p < or = 0.05). The results suggest that rhBMP-2/C could be an effective therapy to restore segmental bone defects.
- Published
- 1998
- Full Text
- View/download PDF
24. Radiomorphometry and biomechanical assessment of recombinant human bone morphogenetic protein 2 and polymer in rabbit radius ostectomy model
- Author
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David C. Buck, John M. Schmitt, Seong Pil Joh, John Brekke, D. L. Chamberland, K.-W. Suh, Donna L. Wheeler, and Jeffrey O. Hollinger
- Subjects
medicine.medical_specialty ,Materials science ,Lagomorpha ,biology ,Radiodensity ,medicine.medical_treatment ,Biomedical Engineering ,Biomaterial ,biology.organism_classification ,Osteotomy ,Bone morphogenetic protein ,law.invention ,Biomaterials ,Endocrinology ,law ,Internal medicine ,medicine ,Recombinant DNA ,Ostectomy ,Bone regeneration ,Biomedical engineering - Abstract
The study objective was to determine the mechanical integrity and radiopacity of regenerated bone within critical-sized defects (CSDs) in radii of rabbits using recombinant human bone morphogenetic protein 2 (rhBMP-2) with a porous, biodegradable poly(D,L-lactic acid) (PDLLA) carrier (designated PLA). Twenty millimeter, unilateral radial ostectomies were created in 96 skeletally mature New Zealand white rabbits. The rabbits were randomly assigned to six treatment groups with two euthanasia periods. Treatment groups included unfilled defect (n = 8), segmental autograft (n = 8), PLA + 0 μg rhBMP-2 (n = 8), PLA + 17 μg rhBMP-2 (n = 8), PLA + 35 μg rhBMP-2 (n = 8), and PLA + 70 μg rhBMP-2 (n = 8). The radiopacity was significantly greater for the 35- and 70-μg rhBMP-2 groups at 4 weeks compared to unfilled controls, PLA only, and 17-μg rhBMP-2 groups and equivalent to the autograft. At 8 weeks all groups receiving rhBMP-2 were equivalent to the autograft and significantly greater than unfilled defects and PLA alone. Similarly, the biomechanical analysis indicated significantly greater torque at failure for the 35-μg rhBMP-2 group compared to all other groups at 4 weeks. By 8 weeks all groups receiving rhBMP-2 and autograft had significantly greater torque than unfilled controls and PLA alone. These radiomorphometric and biomechanical results indicate PLA may be a suitable carrier for rhBMP-2 used for skeletal regeneration. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 43: 365–373, 1998
- Published
- 1998
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25. ChemInform Abstract: Syntheses Utilizing n-Perfluoroalkyl Iodides [RFI, CnF2n+1-I] 2000-2010
- Author
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Robert C. Buck, Peter Michael Murphy, and Christopher S. Baldwin
- Subjects
Organic reaction ,Chemistry ,Organic chemistry ,General Medicine - Abstract
Review: in free-radical reactions, Grignard anion additions to ketones and aldehydes etc.; 231 refs.
- Published
- 2012
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- View/download PDF
26. In vitro Evaluation of the Pollen Extract Cernitin T-60, in the Regulation of Prostate Cell Growth
- Author
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L. Ebeling, Margaret Ross, Ari Lewenstein, A. C. Buck, and Fouad K. Habib
- Subjects
Male ,medicine.medical_specialty ,Urology ,Cell ,Prostatic Hyperplasia ,Cell Count ,medicine.disease_cause ,Cell Line ,3-Oxo-5-alpha-Steroid 4-Dehydrogenase ,Prostate ,Internal medicine ,Pollen ,Tumor Cells, Cultured ,medicine ,Humans ,Cells, Cultured ,Testosterone ,Dose-Response Relationship, Drug ,Plant Extracts ,Cell growth ,business.industry ,Secale ,Prostatic Neoplasms ,Cancer ,medicine.disease ,Molecular biology ,In vitro ,medicine.anatomical_structure ,Endocrinology ,Cell culture ,business ,Cell Division - Abstract
Nine human-derived cancer and non-cancer continuous cell lines were employed to evaluate the relative in vitro activity of the pollen extract, Cernitin T-60. Responses of the cell lines to the drug were assessed by measuring growth and cell survival as determined by cell count. The results demonstrated that of the 9 continuous cell lines tested, only those derived from the human prostate were growth inhibited by the pollen extract, whereas the non-prostate derived cells exhibited variable degrees of resistance to the T-60. The selectivity of the drug for the prostate cell lines was even more pronounced in the hormone-independent models, suggesting that there might be a place for the pollen extract in the control of abnormal growth in hormone-insensitive cells.
- Published
- 1990
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- View/download PDF
27. Treatment of Outflow Tract Obstruction due to Benign Prostatic Hyperplasia with the Pollen Extract Cernilton
- Author
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A. C. Buck, R. Cox, R. W. M. Rees, A. John, and L. Ebeling
- Subjects
Chemotherapy ,medicine.medical_specialty ,Adenoma ,business.industry ,Prostatectomy ,Urology ,medicine.medical_treatment ,Urinary bladder neck obstruction ,Placebo-controlled study ,Hyperplasia ,Placebo ,medicine.disease ,Surgery ,medicine.anatomical_structure ,Prostate ,medicine ,business - Abstract
Whilst prostatectomy remains the "gold standard" for the treatment of outflow tract obstruction due to benign prostatic hyperplasia, medical treatment--if only for symptomatic relief--appears to be an attractive alternative. Most of the pharmacological agents in use block the hormonal or the sympathetic neurological pathways that influence prostate growth and function. All of these drugs are known to have side effects. Sixty patients with outflow obstruction due to benign prostatic hyperplasia (BPH) were entered into a double-blind, placebo-controlled study to evaluate the effect of a 6-month course of the pollen extract, Cernilton. There was a statistically significant subjective improvement with Cernilton (69% of the patients) compared with placebo (30%). There was a significant decrease in residual urine in the patients treated with Cernilton and in the antero-posterior (A-P) diameter of the prostate on ultrasound. However, differences in respect of flow rate and voided volume were not statistically significant. It is concluded that Cernilton has a beneficial effect in BPH and may have a place in the treatment of patients with mild or moderate symptoms of outflow obstruction.
- Published
- 1990
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- View/download PDF
28. Surgical Management of Brachial Plexus Birth Injuries
- Author
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Brian C. Buck and David M. Hunt
- Subjects
Developmental Neuroscience ,Pediatrics, Perinatology and Child Health ,Neurology (clinical) - Published
- 2008
- Full Text
- View/download PDF
29. Chemical modification of enzymes: Active site studies. Edited by J. Eyzaguirre, Ellis Horwood, Chichester, 1987. pp. 187, price £21.50. ISBN 0-7458-0023-8
- Author
-
C. Buck
- Subjects
chemistry.chemical_classification ,biology ,Renewable Energy, Sustainability and the Environment ,Chemistry ,Stereochemistry ,General Chemical Engineering ,Organic Chemistry ,Chemical modification ,Active site ,Pollution ,Inorganic Chemistry ,Fuel Technology ,Enzyme ,biology.protein ,Waste Management and Disposal ,Biotechnology - Published
- 2007
- Full Text
- View/download PDF
30. Entwicklung und Bewertung von Strategien zur Prozessführung von Trennwandkolonnen
- Author
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Georg Fieg and C. Buck
- Subjects
General Chemical Engineering ,General Chemistry ,Industrial and Manufacturing Engineering - Published
- 2012
- Full Text
- View/download PDF
31. Entwicklung von Prozessführungskonzepten für Trennwandkolonnen
- Author
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V. Green, C. Buck, and Georg Fieg
- Subjects
General Chemical Engineering ,Environmental science ,General Chemistry ,Industrial and Manufacturing Engineering - Published
- 2010
- Full Text
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32. ChemInform Abstract: Enantioselective Benzylidene Transfer Reactions Using the Chiral-ate-Iron Benzylidene Complexes (SFeSC)- and (RFeSC)-Cp(CO)(Ph2R*P)Fe=CHC6H5+ (R* = (S)-2-Methylbutyl) and (SFe)-and (RFe)-Cp(CO)(PEt3)Fe=CHC6H5+
- Author
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M. Brookhart and R. C. Buck
- Subjects
Chemistry ,Enantioselective synthesis ,General Medicine ,Medicinal chemistry - Published
- 1990
- Full Text
- View/download PDF
33. Ligneous conjunctivitis involving the cervix. Case report
- Author
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D. C. Buck and C. M. Ridley
- Subjects
Colposcopy ,medicine.medical_specialty ,Past medical history ,medicine.diagnostic_test ,business.industry ,General surgery ,Eye disease ,Obstetrics and Gynecology ,medicine.disease ,Posterior fornix ,Surgery ,medicine.anatomical_structure ,Ligneous conjunctivitis ,Medicine ,Pseudomembranous Conjunctivitis ,business ,Cervix ,Colposcopy clinic - Abstract
A 23-year-old nulliparous woman was examined in the colposcopy clinic at the Royal Northern Hospital, London, in January 1987. She had had a persistent and intermittently offensive vaginal discharge for 3 years. Each time examination had revealed a necrotic, fibrinous, exophytic growth obscuring most of the cervix and posterior fornix. Of note in her past medical history was that she had suffered from a persistent membranous conjunctivis during the first 3 years of life
- Published
- 1990
- Full Text
- View/download PDF
34. Inhibition of Experimental Nephrocalcinosis with a Prostaglandin Synthetase Inhibitor
- Author
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A. C. Buck, D. B. Moffat, R. Li. Davies, and B. Leaker
- Subjects
medicine.medical_specialty ,Urology ,Urinary system ,Indomethacin ,Calcium oxalate ,Prostaglandin ,chemistry.chemical_element ,Calcium ,Kidney ,urologic and male genital diseases ,Pathogenesis ,Lesion ,chemistry.chemical_compound ,Internal medicine ,medicine ,Animals ,Cyclooxygenase Inhibitors ,business.industry ,Rats, Inbred Strains ,medicine.disease ,Calcium Gluconate ,Rats ,Nephrocalcinosis ,Endocrinology ,Flurbiprofen ,chemistry ,Female ,Propionates ,medicine.symptom ,business ,Calcification - Abstract
Nephrocalcinosis was induced in a group of experimental rats by means of intraperitoneal injections of 10% calcium gluconate. Two further groups of rats were treated with indomethacin and flurbiprofen (Froben) before receiving the i.p. calcium gluconate, to study the effects of prostaglandin inhibition on the process of renal parenchymal calcification. Tissue calcification was studied by means of contact microradiography and histology. Quantitative calcium analysis was by means of energy dispersive analysis of X-rays (EDAX). There was a marked inhibition of cortical nephrocalcinosis and a significantly reduced calcium concentration (P less than 0.005) in the animals treated with a prostaglandin inhibitor compared with the animals given i.p. calcium gluconate alone. This study suggests that prostaglandins are involved in the process of renal parenchymal calcification and may be aetiologically significant in the pathogenesis of stone formation.
- Published
- 1983
- Full Text
- View/download PDF
35. The Advantages of99mTc DTPA(Sn) in Dynamic Renal Scintigraphy and Measurement of Renal Function
- Author
-
N. J. Blacklock, M. A. Macleod, and A. C. Buck
- Subjects
Adult ,Male ,Urologic Diseases ,medicine.medical_specialty ,Adolescent ,Urology ,99mtc dtpa ,Renal function ,Radiation hazard ,Kidney ,Renal scintigraphy ,law.invention ,law ,medicine ,Quantitative assessment ,Humans ,Urinary Tract ,Aged ,Gamma camera ,business.industry ,Technetium ,Urography ,Middle Aged ,Upper tract ,Female ,Radiology ,business ,Radioisotope Renography ,Glomerular Filtration Rate ,Pyelogram - Abstract
Summary— The results of excretion urography (IVU) and dynamic renal scintigraphy using 99mTc DTPA(Sn) were compared in 109 urological patients. Computer analysis of the gamma camera data provided a reproducible, accurate, qualitative and quantitative assessment of renal function and was found to be superior to urography in the detection of morphological defects of the renal parenchyma and in the identification of early upper tract obstruction. The radio-isotope study is a safe, non-invasive investigation, easily performed on an out-patient basis, requires no prior preparation and is without significant radiation hazard to the patient.
- Published
- 1980
- Full Text
- View/download PDF
36. Epidermal migration during the healing of suction blisters in rat skin: A scanning and transmission electron microscopic study
- Author
-
William H. Daniels, Stephen C. Pang, and Robert C. Buck
- Subjects
Male ,Suction (medicine) ,Wound Healing ,integumentary system ,Epidermis (botany) ,Blisters ,Anatomy ,Suction ,Biology ,Outer root sheath ,Cell junction ,Rats ,Blister ,medicine.anatomical_structure ,Cell Movement ,Transmission electron microscopy ,Microscopy, Electron, Scanning ,medicine ,Animals ,Female ,Basal lamina ,Epidermis ,medicine.symptom ,Filopodia - Abstract
Fluid-filled blisters, created on the skin of the inner surface of the pinna of heparinized rats by the application of suction, showed an intact basal lamina through which protruded hairs and remnants of hair follicles. The origin of epithelial cells and their spreading over the basal lamina were studied at intervals over 36 hours using scanning and transmission electron microscopy. The majority of epidermal cells arose from the outer root sheath of hair follicles and began to spread radially before 12 hours. By 36 hours the cells were confluent over most of the blister base. Inflammatory cells were few in number and rested mainly on the bare basal lamina rather than on the resurfacing cells. Some elongated epidermal cells showing tapering foot processes appeared to be migrating in from the epidermis at the edge of the blisters. The cells spreading from hair follicles were flat and polygonal. On these sheets of cells a few small folds and many filopodia were present at intercellular junctions and at the free margin of the leading cells. Large numbers of short microvilli covered the surface of some of the epidermal cells, especially at 24 and 36 hours; other epidermal cells were relatively smooth.
- Published
- 1978
- Full Text
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37. From Work to Play: Some Observations on a Popular Nostalgic Theme
- Author
-
Roy C. Buck
- Subjects
Cultural Studies ,History ,Literature and Literary Theory ,Visual Arts and Performing Arts ,Work (electrical) ,Multimedia ,Aesthetics ,Psychology ,computer.software_genre ,computer ,Theme (narrative) - Published
- 1978
- Full Text
- View/download PDF
38. The Treatment of Metastatic Prostatic Cancer with the Slow Release LH-RH Analogue Zoladex ICI 118630
- Author
-
R. W. M. Rees, Keith Griffiths, C. J. Beacock, A. Turkes, R. Zwinck, A. C. Buck, K. Walker, and W. B. Peeling
- Subjects
Male ,medicine.medical_specialty ,Urology ,Acid Phosphatase ,Bone Neoplasms ,Androgen suppression ,Buserelin ,Random Allocation ,medicine ,Humans ,Endocrine system ,Testosterone ,Prospective Studies ,Bone pain ,Lymph node ,Aged ,Metastatic prostatic cancer ,business.industry ,Prostatic Neoplasms ,Cancer ,Luteinizing Hormone ,Middle Aged ,Alkaline Phosphatase ,medicine.disease ,Alternative treatment ,Surgery ,medicine.anatomical_structure ,Delayed-Action Preparations ,Lymphatic Metastasis ,Goserelin ,medicine.symptom ,business - Abstract
Summary— The clinical and endocrine response to a depot preparation of the LH-RH analogue ICI 118630 (Zoladex) was assessed in 55 untreated patients with advanced prostatic cancer. Whereas gonadal androgen suppression was achieved in all patients, subjective and objective clinical response occurred in only 69%, indicated by a relief of bone pain, a decrease in the size of the primary tumour and lymph node metastases and improvement in bone scan appearances. A third of these patients, however, subsequently showed progression of their disease. Serious side effects were not encountered in this study. The depot formulation is a simple, safe and convenient method of administering Zoladex and offers an alternative treatment for metastatic prostatic cancer.
- Published
- 1987
- Full Text
- View/download PDF
39. Bismuth paste in chronic suppurative diseases of the nose, accessory sinuses, ears, and mastoid process
- Author
-
Joseph C. Buck
- Subjects
Mastoid process ,medicine.medical_specialty ,medicine.anatomical_structure ,Otorhinolaryngology ,business.industry ,Medicine ,Dentistry ,ACCESSORY SINUSES ,business ,Nose ,Surgery - Published
- 1910
- Full Text
- View/download PDF
40. ChemInform Abstract: Formation of Cp(CO)(PR3)FeCH(OCH3)C6H5 Complexes via PR3 Substitution Reactions, Hydride Addition to Cp(CO)(PR3)Fe=C(OCH3)C6H+ 5, and Methoxide Addition to Cp(CO)(PR3)Fe=CHC6H+ 5. Kinetic and Thermodynamic Diastereoselectivities. Rela
- Author
-
R. C. Buck and M. Brookhart
- Subjects
Substitution reaction ,chemistry.chemical_compound ,Hydride ,Chemistry ,Inorganic chemistry ,General Medicine ,Methoxide ,Kinetic energy ,Medicinal chemistry - Published
- 1989
- Full Text
- View/download PDF
41. ChemInform Abstract: Synthesis, Spectroscopic Characterization, Dynamics, and Phosphine Trapping of Cp(CO)Fe(η3-CH(R)C6H5) Complexes (R: H, OCH3)
- Author
-
E. Iii Danielson, Robert C. Buck, and Maurice Brookhart
- Subjects
chemistry.chemical_compound ,chemistry ,Physical chemistry ,General Medicine ,Trapping ,Phosphine ,Characterization (materials science) - Published
- 1989
- Full Text
- View/download PDF
42. ChemInform Abstract: Diastereoselective Reactions of Chiral-at-Iron Carbene Complexes C5H5(CO)(PR3)Fe=CHR+. Synclinal Isomers Are More Reactive Than Anticlinal Isomers
- Author
-
Robert C. Buck, Yumin. Liu, and Maurice Brookhart
- Subjects
chemistry.chemical_compound ,chemistry ,General Medicine ,Medicinal chemistry ,Carbene - Abstract
Preparation des complexes et reactions avec les nucleophiles. Les facteurs controlant la diastereoselectivite mettent en jeu les differences de reactivite des isomeres, la nature et la concentration du nucleophile et la force ionique du milieu
- Published
- 1988
- Full Text
- View/download PDF
43. ChemInform Abstract: A NOVEL STEREOSPECIFIC SYNTHESIS OF (.+-.)-LEUKOTRIENE A4 (LTA4) METHYL ESTER
- Author
-
J. C. BUCK, F. ELLIS, and P. C. NORTH
- Subjects
General Medicine - Published
- 1983
- Full Text
- View/download PDF
44. German by TV
- Author
-
George C. Buck
- Subjects
German ,Linguistics and Language ,Political science ,Media studies ,language ,Language and Linguistics ,language.human_language - Published
- 1959
- Full Text
- View/download PDF
45. Tudor Church Music
- Author
-
Edmund Horace Fellowes, Sylvia Townsend Warner, Percy C. Buck, and A. Ramsbotham
- Subjects
History ,media_common.quotation_subject ,Art ,Music ,media_common - Published
- 1923
- Full Text
- View/download PDF
46. Aus Nah und Fern
- Author
-
George C. Buck and Lore Barbara Foltin
- Subjects
Linguistics and Language ,Language and Linguistics - Published
- 1965
- Full Text
- View/download PDF
47. Pathogenic fungus causes density‐ and trait‐mediated trophic cascades in an aquatic community
- Author
-
Carmen C. Harjoe, Julia C. Buck, Jason R. Rohr, Claire E. Roberts, Deanna H. Olson, and Andrew R. Blaustein
- Subjects
Batrachochytrium dendrobatidis ,chytrid fungus ,disease‐mediated ,pathogen ,trophic cascade ,Ecology ,QH540-549.5 - Abstract
Abstract Pathogens can alter species composition and ecosystem function by causing direct and indirect effects on communities. Zoospores of the chytrid fungus Batrachochytrium dendrobatidis (hereafter, Bd), a pathogen implicated in worldwide amphibian declines, can be consumed by filter‐feeding zooplankton and can damage mouthparts of infected amphibian larvae. Consequently, we hypothesized that this pathogen would affect the abundance of zooplankton and survival and feeding abilities of larval amphibian hosts. In turn, this could affect the algal food resources of zooplankton and tadpoles, which can include phytoplankton and periphyton. We tested these hypotheses by manipulating the presence of western toad (Anaxyrus boreas) larvae and Bd in outdoor mesocosms and quantifying the densities of amphibians, zooplankton, phytoplankton, and periphyton. Bd infections reduced amphibian larval densities, but this only weakly benefitted periphyton (a density‐mediated indirect effect). After controlling for larval densities, mesocosms with Bd‐exposed larvae had significantly more periphyton biomass than mesocosms with larvae but no Bd, consistent with infection‐induced mouthpart damage reducing larval feeding rates on attached algae (a trait‐mediated indirect effect). In fact, the estimated trait‐mediated effect of Bd on periphyton biomass was larger than the density‐mediated effect. However, we did not find evidence that Bd exposure triggered a switch to filter‐feeding phytoplankton. The presence of Bd was associated with increased copepod abundance, consistent with zooplankton consuming chytrid zoospores. These results suggest that Bd has the potential to cause both trait‐ and density‐mediated indirect effects that can alter community composition and perhaps the primary productivity of freshwater ecosystems.
- Published
- 2022
- Full Text
- View/download PDF
48. The role of partner support for health behaviours in people living with and beyond cancer: A qualitative study.
- Author
-
Gil N, Fisher A, Beeken RJ, Pini S, Miller N, Buck C, Lally P, and Conway R
- Subjects
- Male, Humans, Female, Qualitative Research, Life Style, Social Support, Health Behavior, Neoplasms therapy
- Abstract
Objective: This study aimed to qualitatively explore how partner support for health behaviours is perceived, received, and utilised in people living with and beyond cancer (LWBC)., Methods: Semi-structured audio interviews were conducted with 24 participants, 15 men and nine women, living with and beyond breast, prostate, and colorectal cancer. Inductive and deductive Thematic Analysis was used to analyse the data., Results: Three key themes with six subthemes were identified relating to partner support for health behaviours: (1) Interdependence (Reciprocity, Overt Control, Influence & Motivation) (2) Concordance (Shared Attitudes & Health Beliefs, Shared Health Behaviour) and (3) Communal Coping (Communal Orientation towards Health and Decision Making, Co-operative Action in Health Behaviour)., Conclusions: Partner support plays a unique and significant role in the health behaviours of people LWBC. Partners play a collaborative role in managing health and facilitating health behaviours, while the high level of concordance in couples may represent a potential barrier to change via the reinforcement of maladaptive health beliefs and behaviours., Implications for Cancer Survivors: Overall, findings demonstrate that partners should be considered and included where possible when designing future behaviour change interventions for people LWBC., (© 2022 The Authors. Psycho-Oncology published by John Wiley & Sons Ltd.)
- Published
- 2022
- Full Text
- View/download PDF
49. Cancer incidence in hypertensives.
- Author
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Buck C and Donner A
- Subjects
- Adult, Aged, Female, Humans, Hypertension etiology, Male, Middle Aged, Neoplasms complications, Neoplasms mortality, Ontario, Statistics as Topic, Hypertension epidemiology, Neoplasms epidemiology
- Abstract
Cancer incidence was measured over a 5-year period (1978 to 1982) in 4067 hypertensive patients, and 10,366 normotensive patients from general practices in southwestern Ontario. For cancer of all sites an elevated incidence was found among hypertensive patients. The elevation was most pronounced among newly diagnosed hypertensive patients, with hypertension of moderate or greater severity, and for sites that have been described in clinical reports as being capable of producing a rise in blood pressure. It is tentatively concluded that the causal direction is from cancer to hypertension, rather than the reverse. If this conclusion is correct, the associations that have been reported between cancer mortality and hypertension may be due to an effect of blood pressure upon survival from cancer.
- Published
- 1987
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