Publications by authors named "Donald David"

Some wetlands in the northern Great Plains support hundreds to thousands of late-stage tadpoles providing important sources of recruitment to the Wood Frog (Lithobates sylvaticus) population while many other wetlands produce none. Relationships between water quality and late-stage tadpole abundance were determined to identify the water quality parameters associated with tadpole abundance. Water samples were collected, and late-stage tadpole abundances were assessed once each year in late June for 12 years in 26 wetlands.

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Objective: This study aimed to determine whether there was an association between the organizational culture and the hospital's readiness to benefit from "Just Culture" training.

Methods: The "Just Culture" Assessment Tool and the Competing Values Framework surveys were administered before and 6 weeks after a structured "Just Culture" training session to 172 care providers and administrators on similar units at two community for-profit hospitals of compatible size and offering comparable services in suburban communities. Data were analyzed for significance using IBM SPSS software.

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Wetlands are abundant throughout the agricultural landscape of central Saskatchewan, Canada, and the biota present in these wetlands may be vulnerable to the toxic effects of pesticides used on nearby crops. We hypothesized that herbicide concentrations would be higher in wetlands on minimum-tillage farms than on organic (no herbicide use) farms, and that the principal transport mechanisms of runoff versus atmospheric deposition could be identified based on the concentrations in these two wetland types. To test these hypotheses, 29 herbicides were monitored for 5 yr in 16 wetlands on minimum-tillage farms and in seven wetlands on organic farms.

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At high concentrations, mercury (Hg) is toxic to vertebrates, causing neurological, behavioral, and teratological dysfunction. Selenium (Se) not only is an essential element but also has a high affinity for Hg, binding to organic methyl mercury at a molar ratio of Se/Hg of 1:1. Ratios of <1 increase risk of Hg toxicity.

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This is a focused update highlighting the most current NCCN Guidelines for diagnosis and management of Lynch syndrome. Lynch syndrome is the most common cause of hereditary colorectal cancer, usually resulting from a germline mutation in 1 of 4 DNA mismatch repair genes (MLH1, MSH2, MSH6, or PMS2), or deletions in the EPCAM promoter. Patients with Lynch syndrome are at an increased lifetime risk, compared with the general population, for colorectal cancer, endometrial cancer, and other cancers, including of the stomach and ovary.

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Sulfonylurea herbicides are applied at relatively low rates (3-40 g ha) to control weeds in a variety of crops grown in the prairie pothole region of south-central Canada. Because of their high phytotoxicity and the likelihood of their transport in surface runoff, there is concern about impacts of sulfonylurea herbicides to wetland ecosystems embedded in agricultural landscapes. In a previous study, dissipation half-lives (DT values) were determined for three sulfonylurea herbicides (thifensulfuron-methyl, ethametsulfuron-methyl, and metsulfuron-methyl), each possessing a hydrolyzable methyl ester linkage.

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The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Colorectal Cancer Screening provide recommendations for selecting individuals for colorectal cancer screening, and for evaluation and follow-up of colon polyps. These NCCN Guidelines Insights summarize major discussion points of the 2015 NCCN Colorectal Cancer Screening panel meeting. Major discussion topics this year were the state of evidence for CT colonography and stool DNA testing, bowel preparation procedures for colonoscopy, and guidelines for patients with a positive family history of colorectal cancer.

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Mercury bioaccumulation models developed for fish provide insight into the sources and transfer of Hg within ecosystems. Mercury concentrations were assessed for 16 fish species of the western reach of Lake Diefenbaker, Saskatchewan, Canada. For top predators (northern pike, Esox Lucius; walleye, Sander vitreum), Hg concentrations were positively correlated to δ(15)N, and δ(15)N to fish age, suggesting that throughout life these fish fed on organisms with increasingly higher trophic values and Hg concentrations.

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A Chirped-Pulse millimeter-Wave (CPmmW) spectrometer is applied to the study of chemical reaction products that result from pyrolysis in a Chen nozzle heated to 1000-1800 K. Millimeter-wave rotational spectroscopy unambiguously determines, for each polar reaction product, the species, the conformers, relative concentrations, conversion percentage from precursor to each product, and, in some cases, vibrational state population distributions. A chirped-pulse spectrometer can, within the frequency range of a single chirp, sample spectral regions of up to ∼10 GHz and simultaneously detect many reaction products.

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Mortality from colorectal cancer can be reduced by early diagnosis and by cancer prevention through polypectomy. These NCCN Guidelines for Colorectal Cancer Screening describe various colorectal screening modalities and recommended screening schedules for patients at average or increased risk of developing colorectal cancer. In addition, the guidelines provide recommendations for the management of patients with high-risk colorectal cancer syndromes, including Lynch syndrome.

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Article Synopsis
  • A series of muscarinic receptor antagonists were created to find an effective treatment for COPD, focusing on compounds with strong M3 receptor effects and fewer side effects.
  • Modifications to initial compounds led to a specific cycloheptyl and quinuclidine sub-series, which were tested with various N-substituents to find the best combination for potency and safety.
  • Following in vitro evaluations, the top-performing compounds were tested in guinea pigs for their effectiveness and side effects, resulting in AZD8683 being chosen for clinical trials due to its promising long-lasting effects and therapeutic profile.
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Oral mucositis affects more than three-fourths of patients undergoing chemotherapy and represents a significant burden to patients and caregivers. Lesions develop as a result of chemotherapeutic agents attacking the rapidly dividing cells of the gastrointestinal tract. Severity can range from mild, painless tissue changes to bleeding ulcerations that prevent oral intake and require narcotic pain relievers.

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The discovery of potent small molecule dual antagonists of the human CCR3 and H(1) receptors is described for the treatment of allergic diseases, for example, asthma and allergic rhinitis. Optimizing in vitro potency and metabolic stability, starting from a CCR1 lead compound, led to compound 20 with potent dual CCR3/H(1) activity and in vitro metabolic stability.

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We have recently described the immunosuppressive properties of AR-C117977 and AR-C122982, representatives of a group of compounds identified as inhibitors of lactate transporters (monocarboxylate transporters; MCTs). These compounds demonstrate the potential therapeutic usefulness of inhibiting MCT-1, but their physical and metabolic properties made them unsuitable for further development. We have therefore tried to find analogues with similar immunosuppressive efficacy and a more suitable profile for oral administration.

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A heated SiC microtubular reactor has been used to decompose acetaldehyde and its isotopomers (CH(3)CDO, CD(3)CHO, and CD(3)CDO). The pyrolysis experiments are carried out by passing a dilute mixture of acetaldehyde (roughly 0.1%-1%) entrained in a stream of a buffer gas (either He or Ar) through a heated SiC reactor that is 2-3 cm long and 1 mm in diameter.

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The second part of this communication focuses on the resolution of issues surrounding the series of hydroxyamide phenoxypiperidine CCR3/H(1) dual antagonists described in Part I. This involved further structural exploration directed at reducing metabolism and leading to the identification of compound 60 with a greatly improved in vivo pharmacokinetic profile.

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The optimization of a new series of muscarinic M(3) antagonists is described, leading to the identification of AZD9164 which was progressed into the clinic for evaluation of its potential as a treatment for COPD.

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Introduction: Public and scientific concern has grown over the last decade in Canada over the cosmetic use of pesticides in urban centers. With this in mind, a national survey was designed to monitor eight commonly used herbicides in urban rivers and streams across Canada.

Materials And Methods: To coordinate sample collections across the country, samples were collected monthly on one of two predetermined dates from April to September, 2007 from 19 sites within 16 watersheds, including 15 sites downstream of urban lands and two reference sites.

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We have designed and developed a laser ablation∕pulsed sample introduction∕mass spectrometry platform that integrates pyrolysis (py) and∕or laser ablation (LA) with resonance-enhanced multiphoton ionization (REMPI) reflectron time-of-flight mass spectrometry (TOFMS). Using this apparatus, we measured lignin volatilization products of untreated biomass materials. Biomass vapors are produced by either a custom-built hot stage pyrolysis reactor or laser ablation using the third harmonic of an Nd:YAG laser (355 nm).

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The optimisation of a new series of high potency muscarinic M3 antagonists, derived from high throughput screening library hit is described.

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A new instrument for monitoring atmospheric CO(2) has been developed based on the measurement of the speed of sound in air. The instrument uses a selective scrubber to yield highly precise and accurate measurements of CO(2) mixing ratios at ambient concentrations. The instrument has a precision of 0.

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Concentrations of 24 trace metals were assessed in gravid ovaries and in muscle of female juvenile and adult female goldeye (Hiodon alosoides), a fish with both low annual growth (16 g/year as adults) and a long life span (maximum longevity of 30 years). It was hypothesized that adult fish with these life-history characteristics would maintain stable concentrations of metals in their tissues with higher levels of essential elements compared with those that are potentially toxic. As hypothesized, the concentration of most metals in muscle of adult female goldeye was similar at all ages, suggesting that uptake and excretion of metals was equal.

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Background: Few options exist for patients with localized esophageal cancer ineligible for conventional therapies. Endoscopic spray cryotherapy with low-pressure liquid nitrogen has demonstrated efficacy in this setting in early studies.

Objective: To assess the safety and efficacy of cryotherapy in esophageal carcinoma.

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Single crystal molecular structure and solution photophysical properties are reported for 1,3-diphenylisobenzofuran (1), of interest as a model compound in studies of singlet fission. For the ground state of 1 and of its radical cation (1(+*)) and anion (1(-*)), we report the UV-visible absorption spectra, and for neutral 1, also the magnetic circular dichroism (MCD) and the decomposition of the absorption spectrum into purely polarized components, deduced from fluorescence polarization. These results were used to identify a series of singlet excited states.

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