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Bourgeois AK, Tank SE, Floyd WC, Emelko MB, Amiri F. Hydrology Predominates Over Harvest History and Landscape Variation to Control Water Quality and Disinfection Byproduct Formation Potentials in Forested Pacific Coast Watersheds. ACS ES T Water 2024; 4:1335-1345. [PMID: 38633370 PMCID: PMC11020162 DOI: 10.1021/acsestwater.3c00471] [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: 08/14/2023] [Revised: 02/15/2024] [Accepted: 02/20/2024] [Indexed: 04/19/2024]
Abstract
Despite the global importance of forested watersheds as sources of drinking water, few studies have examined the effects of forestry on drinking water treatability. Relatively little is known about how the interaction between landscape variation and flow impacts source water quality and what this interaction means for drinking water treatability. To address this knowledge gap, we examined variability in sediments, dissolved organic matter, and disinfection byproduct formation potentials (DBP-FPs) across a range of flow conditions in four small watersheds with contrasting forest harvest histories and soil characteristics on Vancouver Island. Storm event-driven change in streamflow was the primary driver of water quality and DBP-FPs at our sites, with greater changes during stormflow (e.g., a 3-fold increase in dissolved organic carbon concentrations) than those across contrasting watersheds. Flow-driven changes in water quality and DBP-FPs were not significantly different across watersheds with different harvest histories; muted responses may be attributed to widespread second growth forests (i.e., recent harvesting effects may be confounded by historical harvest), forestry practices (e.g., slash burning), or soils with low organic carbon storage. This study suggests that variation in hydrology predominates over harvest history and soil characteristics to drive water quality and DBP-FPs on the east coast of Vancouver Island.
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Affiliation(s)
- Alyssa K. Bourgeois
- Department
of Biological Sciences, University of Alberta, Edmonton T6G 2E9, Canada
| | - Suzanne E. Tank
- Department
of Biological Sciences, University of Alberta, Edmonton T6G 2E9, Canada
| | - William C. Floyd
- Department
of Geography, Vancouver Island University, Nanaimo V9R 5S5, Canada
- Ministry
of Forests, Nanaimo V9T 6E9, Canada
| | - Monica B. Emelko
- Water
Science, Technology & Policy Group, Department of Civil &
Environmental Engineering, University of
Waterloo, Waterloo N2L 3G1, Canada
| | - Fariba Amiri
- Water
Science, Technology & Policy Group, Department of Civil &
Environmental Engineering, University of
Waterloo, Waterloo N2L 3G1, Canada
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2
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Bidlack AL, Bisbing SM, Buma BJ, Diefenderfer HL, Fellman JB, Floyd WC, Giesbrecht I, Lally A, Lertzman KP, Perakis SS, Butman DE, D'Amore DV, Fleming SW, Hood EW, Hunt BPV, Kiffney PM, McNicol G, Menounos B, Tank SE. Climate-Mediated Changes to Linked Terrestrial and Marine Ecosystems across the Northeast Pacific Coastal Temperate Rainforest Margin. Bioscience 2021. [PMCID: PMC8169312 DOI: 10.1093/biosci/biaa171] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Coastal margins are important areas of materials flux that link terrestrial and marine ecosystems. Consequently, climate-mediated changes to coastal terrestrial ecosystems and hydrologic regimes have high potential to influence nearshore ocean chemistry and food web dynamics. Research from tightly coupled, high-flux coastal ecosystems can advance understanding of terrestrial–marine links and climate sensitivities more generally. In the present article, we use the northeast Pacific coastal temperate rainforest as a model system to evaluate such links. We focus on key above- and belowground production and hydrological transport processes that control the land-to-ocean flow of materials and their influence on nearshore marine ecosystems. We evaluate how these connections may be altered by global climate change and we identify knowledge gaps in our understanding of the source, transport, and fate of terrestrial materials along this coastal margin. Finally, we propose five priority research themes in this region that are relevant for understanding coastal ecosystem links more broadly.
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Affiliation(s)
- Allison L Bidlack
- Alaska Coastal Rainforest Center, University of Alaska Southeast in Juneau, Alaska, United States, when this article was prepared. Bidlack is presently affiliated with the National Marine Fisheries Service, Alaska Fisheries Science Center, Juneau, Alaska, United States
| | - Sarah M Bisbing
- Department of Natural Resources and Environmental Science, University of Nevada–Reno, Reno, Nevada, United States
| | - Brian J Buma
- Department of Integrative Biology, University of Colorado, Denver, Colorado, in the United States
| | - Heida L Diefenderfer
- Pacific Northwest National Laboratory, Marine Sciences Laboratory, Sequim, Washington, and with the University of Washington School of Environmental and Forest Sciences, Seattle, Washington, United States
| | - Jason B Fellman
- Alaska Coastal Rainforest Center, University of Alaska Southeast in Juneau, Alaska, United States, when this article was prepared. Bidlack is presently affiliated with the National Marine Fisheries Service, Alaska Fisheries Science Center, Juneau, Alaska, United States
| | - William C Floyd
- British Columbia Ministry of Forests, Lands, and Natural Resource Operations and with Vancouver Island University in Nanaimo, British Columbia, Canada
| | - Ian Giesbrecht
- Hakai Institute in Heriot Bay, British Columbia, and with the School of Resource and Environmental Management, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Amritpal Lally
- Vancouver Island University, Vancouver, British Columbia, Canada
| | - Ken P Lertzman
- School of Resource and Environmental Management, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Steven S Perakis
- US Geological Survey, Forest and Rangeland Ecosystem Science Center, Corvallis, Oregon, United States
| | - David E Butman
- School of Environmental and Forest Sciences and with Civil and Environmental Engineering at the University of Washington, Seattle, Washington, United States
| | - David V D'Amore
- US Forest Service Pacific Northwest Research Station, Juneau, Alaska, United States
| | - Sean W Fleming
- Water Resources Graduate Program and the College of Earth, Ocean, and Atmospheric Sciences at Oregon State University, Corvallis, Oregon, and with the Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, British Columbia, Canada; he is also now with the National Water and Climate Center of the US Department of Agriculture Natural Resources Conservation Service, Portland, Oregon, United States
| | - Eran W Hood
- Department of Natural Sciences, University of Alaska Southeast, Juneau, Alaska, United States
| | - Brian P V Hunt
- Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, British Columbia, and with the Hakai Institute, in Heriot Bay, British Columbia, Canada
| | - Peter M Kiffney
- National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Northwest Fisheries Science Center, Watershed Program, Seattle, Washington, United States
| | - Gavin McNicol
- Department of Earth and Environmental Science, University of Illinois, Chicago, Chicago, Illinois, United States
| | - Brian Menounos
- Department of Geography, University of Northern British Columbia, Prince George, British Columbia, Canada
| | - Suzanne E Tank
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, in Canada
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3
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Evans DM, Schoenholtz SH, Wigington PJ, Griffith SM, Floyd WC. Spatial and temporal patterns of dissolved nitrogen and phosphorus in surface waters of a multi-land use basin. Environ Monit Assess 2014; 186:873-887. [PMID: 24046242 DOI: 10.1007/s10661-013-3428-4] [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] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 09/05/2013] [Indexed: 06/02/2023]
Abstract
Research on relationships between dissolved nutrients and land-use at the watershed scale is a high priority for protecting surface water quality. We measured dissolved nitrogen (DN) and ortho-phosphorus (P) along 130 km of the Calapooia River (Oregon, USA) and 44 of its sub-basins for 3 years to test for associations with land-use. Nutrient concentrations were analyzed for spatial and seasonal patterns and for relationships with land-use and stream discharge. Ortho-P and DN were higher in lower-elevation sub-basins dominated by poorly drained soils and agricultural production compared with higher-elevation sub-basins dominated by well-drained soils and forests. Eight lower basins had at least one sample period with nitrate-N > 10 mg L(-1). The Calapooia River had lower concentrations of dissolved nutrients compared with lower sub-basins, often by an order of magnitude. Dissolved organic N represented a greater proportion of DN in the upper forested sub-basins. Seasonal nutrient concentrations had strong positive correlations to the percent of a sub-basin that was managed for agriculture in all seasons (p values ≤ 0.019) except summer. Results suggest that agricultural lands are contributing to stream nutrient concentrations. However, poorly drained soils in agricultural areas may also contribute to the strong relationships that we found between dissolved nutrients and agriculture.
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Affiliation(s)
- Daniel M Evans
- Dept. of Crop and Soil Environmental Sciences, Virginia Tech, 330 Smyth Hall, Blacksburg, VA, 24061, USA,
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4
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Floyd WC, Baker SE, Valdez CA, Stolaroff JK, Bearinger JP, Satcher JH, Aines RD. Evaluation of a carbonic anhydrase mimic for industrial carbon capture. Environ Sci Technol 2013; 47:10049-10055. [PMID: 23883067 DOI: 10.1021/es401336f] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Zinc(II) cyclen, a small molecule mimic of the enzyme carbonic anhydrase, was evaluated under rigorous conditions resembling those in an industrial carbon capture process: high pH (>12), nearly saturated salt concentrations (45% K2CO3) and elevated temperatures (100-130 °C). We found that the catalytic activity of zinc cyclen increased with increasing temperature and pH and was retained after exposure to a 45% w/w K2CO3 solution at 130 °C for 6 days. However, high bicarbonate concentrations markedly reduced the activity of the catalyst. Our results establish a benchmark level of stability and provide qualitative insights for the design of improved small-molecule carbon capture catalysts.
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Affiliation(s)
- William C Floyd
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory , 7000 East Avenue, Livermore, California 94550, United States
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Andolina CM, Klemm PJ, Floyd WC, Fréchet JMJ, Raymond KN. Analysis of Lanthanide Complex Dendrimer Conjugates for Bimodal NIR and MRI Imaging. Macromolecules 2012; 45:8982-8990. [PMID: 23226878 DOI: 10.1021/ma302206g] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Advances in clinical diagnostic instrumentation have enabled some imaging modalities to be run concurrently. For diagnostic purposes, multimodal imaging can allow for rapid location and accurate identification of a patient's illness. The paramagnetic and near Infra-red (NIR) properties of Dy(III) and Yb(III) are interesting candidates for the development of bimodal NIR and magnetic resonance imaging (MRI) contrast agents. To enhance their intrinsic bimodal properties, these lanthanides were chelated using the hexadentate-all-oxygen-donor-ligand TREN-bis-(1-Me)-3,2-HOPO-TAM-NX (NX, where X = 1, 2 or 3) and subsequently conjugated to the esteramide dendrimer (EA), to improve bioavailability, solubility, and relaxivity. Of these new complexes synthesized and evaluated, DyN1-EA had the largest ionic T(1) relaxivity, 7.60 mM(-1) s(-1), while YbN3-EA had the largest ionic T(2) relaxivity with a NIR quantum yield of 0.17 % when evaluated in mouse serum. This is the first Yb(III) bimodal NIR/T(2) MRI contrast agent of its kind evaluated.
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Affiliation(s)
- Christopher M Andolina
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
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6
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Klemm PJ, Floyd WC, Smiles DE, Fréchet JMJ, Raymond KN. Improving T₁ and T₂ magnetic resonance imaging contrast agents through the conjugation of an esteramide dendrimer to high-water-coordination Gd(III) hydroxypyridinone complexes. Contrast Media Mol Imaging 2012; 7:95-9. [PMID: 22344885 DOI: 10.1002/cmmi.483] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Commercial gadolinium magnetic resonance imaging (MRI) contrast agents are limited by low relaxivity (r₁) and coordination to only a single water molecule (q = 1). Consequently, gram quantities of these agents must be injected to obtain sufficient diagnostic contrast. In this study, MRI contrast agents for T(1) and T₂ relaxivity were synthesized using hydroxypyridinone and terephthalamide chelators with mesityl and 1,4,7-triazacyclononane capping moieties. When covalently conjugated to a highly biocompatible esteramide dendrimer, T₂ relaxation rates up to 52 mm(-1) s(-1) and T₁ relaxation rates up to 31 mm(-1) s(-1) per gadolinium were observed under clinically relevant conditions. These values are believed to be brought about by using a dendritic macromolecule to decrease the molecular tumbling time of the small molecule complexes. These agents also show high aqueous solubility and low toxicity in vitro. In this study we report six new compounds: three discrete complexes and three dendrimer conjugates.
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Affiliation(s)
- Piper J Klemm
- Department of Chemistry, University of California, Berkeley, CA 94720-1460, USA
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7
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Koziol L, Valdez CA, Baker SE, Lau EY, Floyd WC, Wong SE, Satcher JH, Lightstone FC, Aines RD. Toward a Small Molecule, Biomimetic Carbonic Anhydrase Model: Theoretical and Experimental Investigations of a Panel of Zinc(II) Aza-Macrocyclic Catalysts. Inorg Chem 2012; 51:6803-12. [DOI: 10.1021/ic300526b] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lucas Koziol
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore,
California 94550, United States
| | - Carlos A. Valdez
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore,
California 94550, United States
| | - Sarah E. Baker
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore,
California 94550, United States
| | - Edmond Y. Lau
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore,
California 94550, United States
| | - William C. Floyd
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore,
California 94550, United States
| | - Sergio E. Wong
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore,
California 94550, United States
| | - Joe H. Satcher
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore,
California 94550, United States
| | - Felice C. Lightstone
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore,
California 94550, United States
| | - Roger D. Aines
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore,
California 94550, United States
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8
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Klemm PJ, Floyd WC, Andolina CM, Fréchet JMJ, Raymond KN. Conjugation to Biocompatible Dendrimers Increases Lanthanide T2 Relaxivity of Hydroxypyridinone (HOPO) Complexes for Magnetic Resonance Imaging (MRI). Eur J Inorg Chem 2012; 2012:2108-2114. [PMID: 23539072 PMCID: PMC3607537 DOI: 10.1002/ejic.201101167] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2011] [Indexed: 11/07/2022]
Abstract
Magnetic resonance imaging (MRI) contrast agents represent a worldwide billion-dollar market annually. While T1 relaxivity enhancement contrast agents receive greater attention and a significantly larger market share, the commercial potential for T2 relaxivity enhancing contrast agents remains a viable diagnostic option due to their increased relaxivity at high field strengths. Improving the contrast and biocompatibility of T2 MRI probes may enable new diagnostic prospects for MRI. Paramagnetic lanthanides have the potential to decrease T1 and T2 proton relaxation times, but are not commercially used in MRI diagnostics as T2 agents. In this article, oxygen donor chelates (hydroxypyridinone, HOPO, and terephthalamide, TAM) of various lanthanides are demonstrated as biocompatible macromolecular dendrimer conjugates for the development of T2 MRI probes. These conjugates have relaxivities up to 374 mm-1s-1 per dendrimer, high bioavailability, and low in vitro toxicity.
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Affiliation(s)
- Piper J. Klemm
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720 United States
| | - William C. Floyd
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720 United States
| | | | - Jean M. J. Fréchet
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720 United States
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Kenneth N. Raymond
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720 United States
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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Floyd WC, Datta GK, Imamura S, Kieler-Ferguson HM, Jerger K, Patterson AW, Fox ME, Szoka FC, Fréchet JMJ, Ellman JA. Chemotherapeutic evaluation of a synthetic tubulysin analogue-dendrimer conjugate in c26 tumor bearing mice. ChemMedChem 2011; 6:49-53. [PMID: 20973119 DOI: 10.1002/cmdc.201000377] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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10
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Chen B, van der Poll DG, Jerger K, Floyd WC, Fréchet JMJ, Szoka FC. Synthesis and properties of star-comb polymers and their doxorubicin conjugates. Bioconjug Chem 2011; 22:617-24. [PMID: 21375296 DOI: 10.1021/bc100400u] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We describe a six-step synthesis to water-soluble doxorubicin (DOX)-loaded biodegradable PEGylated star-comb polymers with favorable pharmaceutical properties by atom transfer radical polymerization (ATRP) starting with a commercially available tripentaerythritol carrying eight reactive sites. The low polydispersity polymers degrade in a stepwise manner into lower molecular weight (MW) fragments by 15 days at 37 °C at either pH 5.0 or pH 7.4. The half-life of the star-comb polymers in blood is dependent upon the molecular weight; the 44 kDa star-comb has a t(1/2, β) of 30.5 ± 2.1 h, which is not significantly changed (28.6 ± 2.7 h) when 6.6 wt % of DOX is attached to it via a pH-sensitive hydrazone linker. The star-comb polymers have low accumulation in organs but a high accumulation in C26 flank tumors implanted in Balb/C mice. The hydrodynamic diameter of polymer-DOX conjugates measured by dynamic light scattering increases from 8 to 35 to 41 nm as the loading is increased from 6.6 to 8.4 to 10.2 wt %. Although there is no significant difference in the t(1/2, β) or in the accumulation of polymer-DOX in C-26 tumors, the uptake of polymer in the spleen is significantly higher for polymers with DOX loadings greater than 6.6 wt %. Polymer accumulation in other vital organs is independent of the DOX loading. The facile synthesis, biodegradability, long circulation time, and high tumor accumulation of the attached drug suggests that the water-soluble star-comb polymers have promise in therapeutic applications.
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Affiliation(s)
- Bo Chen
- Department of Bioengineering, Therapeutic Sciences and Pharmaceutical Chemistry, University of California, San Francisco , California 94143-0912, United States
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Floyd WC, Klemm PJ, Smiles DE, Kohlgruber AC, Pierre VC, Mynar JL, Fréchet JMJ, Raymond KN. Conjugation effects of various linkers on Gd(III) MRI contrast agents with dendrimers: optimizing the hydroxypyridinonate (HOPO) ligands with nontoxic, degradable esteramide (EA) dendrimers for high relaxivity. J Am Chem Soc 2011; 133:2390-3. [PMID: 21294571 DOI: 10.1021/ja110582e] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
One essential requirement for more sensitive gadolinium-based MRI contrast agents is to slow the molecular tumbling of the gadolinium(III) ion, which increases the gadolinium's relaxivity (i.e., its ability to speed up the NMR relaxation of nearby water molecules). One route to this is through conjugation to high-molecular-weight polymers such as dendrimers. In this work, amine-functionalized TREN-bis(1,2-HOPO)-TAM-ethylamine and TREN-bis(1-Me-3,2-HOPO)-TAM-ethylamine ligands have been synthesized and attached to biocompatible 40 kDa esteramide (EA)- and poly-l-lysine (PLL)-based dendrimers capable of binding up to eight gadolinium complexes. These conjugates have T(1) relaxivities of up to 38.14 ± 0.02 mM(-1) s(-1) per gadolinium at 37 °C, corresponding to relaxivities of up to 228 mM(-1) s(-1) per dendrimer molecule. This relaxivity expressed on a "per Gd" basis is several times that of the small-molecule complexes and an order of magnitude higher than that of current commercial agents. Because of their high performance and low toxicity, these macromolecules may constitute an attractive complement to currently available gadolinium(III)-based contrast agents.
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Affiliation(s)
- William C Floyd
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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12
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van der Poll DG, Kieler-Ferguson HM, Floyd WC, Guillaudeu SJ, Jerger K, Szoka FC, Fréchet JM. Design, synthesis, and biological evaluation of a robust, biodegradable dendrimer. Bioconjug Chem 2010; 21:764-73. [PMID: 20353169 DOI: 10.1021/bc900553n] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
PEGylated dendrimers are attractive for biological applications due to their tunable pharmacokinetics and ability to carry multiple copies of bioactive molecules. The rapid and efficient synthesis of a robust and biodegradable PEGylated dendrimer based on a polyester-polyamide hybrid core is described. The architecture is designed to avoid destructive side reactions during dendrimer preparation while maintaining biodegradability. Therefore, a dendrimer functionalized with doxorubicin (Dox) was prepared from commercial starting materials in nine, high-yielding linear steps. Both the dendrimer and Doxil were evaluated in parallel using equimolar dosage in the treatment of C26 murine colon carcinoma, leading to statistically equivalent results with most mice tumor-free at the end of the 60 day experiment. The attractive features of this dendritic drug carrier are its simple synthesis, biodegradability, and versatility for application to a variety of drug payloads with high drug loadings.
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Affiliation(s)
- Derek G van der Poll
- College of Chemistry, University of California, Berkeley, California 94720-1460, USA
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13
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Floyd WC, Schoenholtz SH, Griffith SM, Wigington PJ, Steiner JJ. Nitrate-nitrogen, land use/land cover, and soil drainage associations at multiple spatial scales. J Environ Qual 2009; 38:1473-1482. [PMID: 19465723 DOI: 10.2134/jeq2008.0099] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Managing non-point-source pollution of water requires knowledge of land use/land cover (LULC) influences at altering watershed scales. To gain improved understanding of relationships among LULC, soil drainage, and dissolved nitrate-N dynamics within the Calapooia River Basin in western Oregon, we selected 44 watersheds ranging in size between 3 and 33 km(2) for monthly synoptic sampling of surface water quality between October 2003 and September 2004. Seasonal associations were examined between dissolved nitrate-N and proportion of woody vegetation or poorly drained soils at differing scales (10, 20, 30, 60, 90, 150, 300 m, and entire watershed), which we defined as influence zones (IZs), surrounding stream networks. Correlations between nitrate-N and proportion woody vegetation or poorly drained soil at each IZ were analyzed for differences using the Hotelling-Williams test. We observed negative correlations (r = -0.81 to -0.94) between nitrate-N and proportion of woody vegetation during winter and spring. Poorly drained soils had positive correlations (r = 0.63-0.87) with nitrate-N. Altering the scale of analysis significantly changed correlations between nitrate-N and woody vegetation, with IZs <150 m being stronger than the watershed scale during winter. However, absolute differences in correlation values were small, indicating minimal ecological consequence for significant differences among scales. In contrast, nitrate-N correlations with poorly drained soil were stronger at the watershed scale than the 10- through 90-m IZs during winter and spring, and absolute differences were sufficient to suggest that scale is ecologically important when determining associations between dissolved nitrate-N and poorly drained soils.
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Affiliation(s)
- William C Floyd
- Dep. of Forest Engineering, Resources and Management, Oregon State Univ., Corvallis, OR 97331, USA
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14
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Kozikowski AP, Floyd WC. Borohydride induced cleavage of azo derivatives of β-ketoesters. A useful variant of the Japp-Klingemann reaction for C-nucleoside synthesis. Tetrahedron Lett 1978. [DOI: 10.1016/s0040-4039(01)88971-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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15
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Kozikowski AP, Floyd WC, Kuniak MP. 1,3-Diethoxycarbonylallene: an active dienophile and ethoxycarbonylketen equivalent in the synthesis of antibiotic C-nucleosides. ACTA ACUST UNITED AC 1977. [DOI: 10.1039/c39770000582] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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