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A Meta-Analysis and Risk Assessment of Heavy Metal Uptake in Common Garden Vegetables.LeCoultre, Trent David 01 December 2001 (has links) (PDF)
Peer reviewed literature was searched to identify research pertaining to the uptake of heavy metals (As, Cd, Pb and Zn) by vegetables (cabbage, carrot, lettuce, and radish). The objectives of this research were to 1) determine the relationship between heavy metal concentrations in the soil and heavy metal concentrations in vegetables, and 2) determine the level of risk associated with exposure to heavy metals through ingestion of contaminated vegetables. Highly variable estimates and biologically implausible regression equations resulted from this meta-analysis. Exposure to arsenic through the ingestion of lettuce grown on contaminated soil significantly increases cancer risk, especially in children. Highly variable hazard quotients prevent strong statements concerning toxic effects from exposure to Pb, Cd, or Zn. A more in-depth meta-analysis (multiple-regression and nonlinear curve-fitting) and an upgrade in data reporting standards are recommended.
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Properties of Conductance and Inhibition of Proton Channels: M2 from Influenza A Virus and Fo from Escherichia coli ATP SynthaseMoffat, Jeffrey C. 30 June 2006 (has links) (PDF)
Proton channels are essential for many of the processes of life. The influenza A viral protein M2 is responsible for sensing the conditions necessary for viral RNA release. The proton-translocating FoF1 ATPase (ATP synthase) uses a proton gradient to drive adenosine triphosphate (ATP) synthesis. We have directly measured proton uptake in vesicles containing reconstituted M2 or FO by monitoring external pH after addition of valinomycin to vesicles with 100-fold diluted external [K+]. This proton flux assay was utilized to quantify proton flux through single M2 and Fo channels. Contrary to previous reports, proton uptake by M2 was not significantly altered by acidification of the extravesicular pH. We conclude that pH only weakly affects proton flux through M2 in the pH range of 5.4 - 7.0. Theoretical analysis utilized for such vesicle uptake assays illuminates the appropriate time scale of the initial slope and an important limitation that must be placed on inferences about channel ion selectivity. The rise in pH over 10 seconds after ionophore addition yielded time-averaged single channel conductances of 0.35±0.2 aS and 0.72±0.4 aS at pH 5.4 and 7.0 respectively. Such a low time-average conductance implies that M2 is only conductive 10^-6 to 10^-4 of the time. M2 selectivity for hydrogen over potassium is ~10^7. Fo translocates protons across membranes, converting electrochemical energy to rotational inertia. Previous experiments have been partially confounded by a contaminating channel, CL, which co-purifies with Fo and leaks cations. CL activity is shown to not decrease following deletion of the previously uncharacterized yraM open reading frame of E. coli. Fo purified from a deletion strain lacking yraM is just as active as Fo purified from the wild-type strain. Using Fo from the deletion strain, the single-hit hypothesis of DCCD inhibition of passive proton flux through Fo was examined. A DCCD-induced reduction in ATP synthase activity correlates with a reduction in the total initial slope, the number of functional Fo per µg protein, and the single channel proton flux. At least 2 DCCD per Fo are required to totally inactivate passive proton flux. M2 and Fo have similar single channel conductances but different open probabilities.
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Development of an Exercise Test to Predict VO2max in Children and AdolescentsBlack, Nathan E. 17 April 2009 (has links) (PDF)
The purpose of this study was to evaluate the use of nonexercise (N-EX) data, specifically, the Perceived Functional Ability (PFA) and Physical Activity Rating (PA-R) questionnaires, with the treadmill walk-jog-run protocol to estimate VO2max in 12 to 17 year old boys and girls. Ninety-one participants (49 males and 42 females) took part in this study. Data were collected via PFA and PA-R questionnaires, a walk-jog-run submaximal treadmill test, and a maximal graded exercise test (GXT). Data collected included gender, age, height, weight, PFA and PA-R scores, heart rate (HR), treadmill speed, maximal treadmill grade, respiratory exchange ratio (RER), rating of perceived exertion (RPE), and VO2max. Regression analysis resulted in the development of two valid and reliable models to predict VO2max. Nonexercise and submaximal exercise test data were used to build the following model: VO2max (mL∙kg-¹∙min-¹) = 11.201 + (6.877 x Gender; 0 = female; 1 = male) + (3.573 x treadmill speed; mph) – (0.174 x kg) + (0.405 x PFA score) + (0.653 x PA-R score) + (1.019 x age). The model resulted in an R2 = 0.69 and a SEE = 5.16 mL∙kg-¹∙min-¹. Maximal exercise test data were used to build the following model: VO2max (mL∙kg-¹∙min-¹) = -3.264 + (3.359 x Gender; 0 = female; 1 = male) – (0.082 x kg) + (7.351 x treadmill speed; mph) + (1.750 x maximal treadmill grade). The model resulted in an R2 = 0.88 and a SEE = 3.16 mL∙ kg-¹∙min-¹. The cross-validation PRESS statistics for both models demonstrated minimal shrinkage in the accuracy of the regression model. The results of this study demonstrate, for the first time, that N-EX data can be used to accurately predict VO2max in youth. The submaximal and maximal exercise tests validated in this study can be used to assess cardiorespiratory fitness of youth having a wide range on interests and fitness levels. In addition, the use of PFA and PA-R questionnaires enforces initiatives to increase physical activity among youth. Both exercise tests use a self-selected treadmill speed that elicits a steady-state HR of 70% of the participants age-predicted maximal HR. The use of a self-selected walking, jogging, or running speed accommodates youth with different levels of physical fitness, motivation, and interests. The exercise test protocol presented in this study is practical for use in schools, athletic facilities, and community fitness centers. The equipment required to administer the exercise test presented in this study is limited to a treadmill and a HR monitor. Together with the use of PFA and PA-R questionnaires, the submaximal and maximal exercise tests are efficacious to coaches, fitness professionals, and physical educators in a variety of settings.
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Environmental and Nutritional Chemistry of Wild Harvested Blueberries vs. Commercial Blueberries: Depositional and Uptake Chemistry and Human Health AssessmentMaynard, Christy Ann Marie 30 November 2023 (has links)
In northern Saskatchewan, Canada, there are several active and decommissioned uranium mines and mills licensed by Canada's nuclear regulator, the Canadian Nuclear Safety Commission (CNSC). In these areas, Indigenous communities harvest traditional foods and Canadian diet studies have identified wild berries as an important part of their diet (Furgal, Powell, & Myers, 2005), (Roseanne C. Schuster, 2011), (Health Canada, 2010). Food ingestion is recognized as an exposure pathway of anthropogenic and naturally occurring radioactive materials and trace metals (Kuhnlein & Chan, 2000) and some communities may be concerned their traditional foods are contaminated from facility operations.
Wild blueberries and the soil the plant roots grew in were sampled approximately 10-25 kms away from CNSC-licensed facilities in northern Saskatchewan. As a comparison, commercially-available blueberries and soil were collected from Ontario farms and blueberries were obtained from grocery stores. Samples were analyzed for trace elemental concentrations by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and radionuclide activity concentrations were measured. Annual ingestion dose for blueberry consumption was conservatively estimated to be 0.0079 mSv/a. The blueberry results were compared to international guidelines and published literature and were not found to pose an ingestion health risk. The activity concentrations in blueberries ranged between 0.001-0.006 Bq/g d.w. for ²¹⁰Po and 0.003-0.005 Bq/g d.w. for ²¹⁰Pb and the concentrations of cadmium and arsenic in blueberries ranged between 0.002-0.07 μg/g and 0.0002-0.007 μg/g, respectively. This research project identifies geochemical relationships between radionuclides and trace elements in blueberries, examines the uptake chemistry, environmental cycling of radionuclides and trace elements, and the soil mineralogy and composition, helps inform CNSC's regulatory decision-making process, and supports future human health risk communication with Indigenous communities.
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Growth and metal uptake capacity of microalgae under exposure to chromiumThanh, Son Dao, Nguyen, Hong-Son Le, Vo, Tan-Minh, Vo, Thi-My-Chi, Phan, The-Huy, Bui, Thi -Nhu-Phuong 16 January 2019 (has links)
Microalgae play a key function in aquatic ecosystems. Their development and growth are strongly regulated by trace metals as essential elements. However, trace metals could cause negative effects when exceeding certain concentrations in the environment. In this study we tested the development and growth rate of two freshwater microalgae, the cyanobacterium Pseudanabeana mucicola and
the green alga Pediastrum duplex, from Vietnam over the period of 14 days exposing to chromium (Cr) at the concentrations up to 1,936 μg L-1. Besides, the Cr uptake and absorption by P. mucicola were evaluated over 7 days incubated in medium containing 422 μg Cr L-1. The results showed that Cr at the concentrations up to 1,078 μg L-1 did not inhibit the development and growth rate of P. mucicola. Similarly, concentration of 224 μg Cr L-1 had no adverse effects on growth of P. duplex. The cyanobacterium P. mucicola could make a reduction up to 71% of Cr in the test medium, hence become a distinguished candidate for metal phytoremediation. To the best of our knowledge this is the first investigation on the responses and absorption of Cr by freshwater microalgae from Vietnam. / Vi tảo đóng vai trò quan trọng trong hệ sinh thái thủy vực. Sự sinh trưởng và phát triển của chúng được điều tiết mạnh mẽ bởi kim loại vi lượng như những yếu tố thiết yếu. Tuy nhiên, những kim loại vi lượng này có thể gây ra những ảnh hưởng tiêu cực khi vượt quá nồng độ nhất định trong môi trường. Trong nghiên cứu này, chúng tôi thử nghiệm sự phát triển và tốc độ phát triển của hai loài vi tảo nước ngọt: loài tảo lam Pseudanabeana mucicola và loài tảo lục Pediastrum duplex có nguồn gốc từ Việt Nam trong thời gian 14 ngày phơi nhiễm với crôm (Cr) tại nồng độ lên tới 1.936 μg L-1. Bên cạnh đó, sự hấp thu Cr của P. mucicola cũng đã được đánh giá trong thời gian 7 ngày nuôi trong môi trường chứa 422 μg Cr L-1. Kết quả cho thấy Cr tại nồng độ lên tới 1.078 μg L-1
không kìm hãm sự phát triển và tốc độ sinh trưởng của P. mucicola. Tương tự, tại nồng độ 224 μg Cr L-1 không có bất kì ảnh hưởng tiêu cực đến sự phát triển của P. duplex. Loài tảo lam P. mucicola có thể làm giảm 71% hàm lượng Cr trong môi trường thí nghiệm, vì vậy được xem là ứng viên sáng giá cho quá trình xử lý môi trường ô nhiễm kim loại bằng thực vật . Theo hiểu biết của nhóm tác giả, đây là nghiên cứu đầu tiên về đáp ứng và hấp thu Cr bởi những vi tảo nước ngọt có nguồn gốc từ Việt Nam.
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Internalization of Extracellular ATP in Cancer Cells and Development of New Generations of Anticancer Glucose Transport InhibitorsQian, Yanrong January 2014 (has links)
No description available.
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Ionically Crosslinked Chitosan NanocarriersCai, Yuhang January 2017 (has links)
No description available.
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GYPSUM AND CARBON AMENDMENT’S INFLUENCE ON SOIL PROPERTIES, GREENHOUSE GAS EMISSIONS, GROWTH AND NUTRIENT UPTAKE OF RYEGRASS (Lolium perenne)Walia, Maninder Kaur 14 October 2015 (has links)
No description available.
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Effects of Elevated Carbon Dioxide and Chronic Warming on Nitrogen (N) Uptake and Assimilatory Proteins of Tomato Roots Provided Different Forms of Inorganic N (Nitrate and Ammonium)Jayawardena, Dileepa M. January 2015 (has links)
No description available.
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Phytoremediation of Historic Lead Shot Contaminated Soil, Grand Valley Ranch, Northeast OhioTening Ndifet, Claret Mengwi January 2016 (has links)
No description available.
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