13 research outputs found
A Niche for Infectious Disease in Environmental Health: Rethinking the Toxicological Paradigm
A framework for stakeholder identification in concept mapping and health research: a novel process and its application to older adult mobility and the built environment
Kinetics and Pathways of the Aqueous Photolysis of Pharmaceutical Pollutants: A Versatile Laboratory or Remote Learning Investigation
In this laboratory experiment, students explore the aquatic photochemical fate of ranitidine and cimetidine, two common wastewater-derived pharmaceutical pollutants. It provides an engaging environmental context for students to develop knowledge of reaction kinetics and photochemistry, as well as skill using analytical instrumentation. This versatile experiment consists of two basic modules, three optional advanced modules, and additional add-ons that may be performed in various combinations to meet the unique learning objectives of general, analytical, physical, and environmental chemistry courses and science outreach activities. It may be performed as a traditional lab experiment or as an entirely remote exercise with an increased focus on data analysis and interpretation using provided example data sets. All photolysis experiments are carried out by preparing solutions of ranitidine or cimetidine in various matrices, irradiating the samples, and periodically removing subsamples for HPLC analysis of the compound of interest. Pseudo-first-order kinetic plots are then generated to determine rate constants that are used to draw conclusions about photolysis pathways or to calculate additional kinetic parameters. In the two basic modules, cimetidine is found to degrade appreciably only when irradiated in the presence natural organic matter (NOM), indicating an indirect, photosensitized degradation pathway. In contrast, ranitidine degrades in pure buffer and in the presence of NOM with comparable rate constants, highlighting the predominant role of direct photolysis. In the advanced modules, students calculate ranitidine direct photolysis quantum yields and examine the significance of singlet oxygen as a photochemically produced reactive intermediate. The two basic modules may be completed in two three- to five-hour lab periods while the advanced modules require additional time. This experiment requires only a HPLC, inexpensive chemicals, and common glassware and lab equipment if performed in person, and a personal computer if performed remotely.</p
Kinetics and Pathways of the Aqueous Photolysis of Pharmaceutical Pollutants: A Versatile Laboratory or Remote Learning Investigation
In this laboratory experiment, students explore the aquatic photochemical fate of ranitidine and cimetidine, two common pharmaceutical pollutants found in wastewater. It provides an engaging environmental context for students to develop knowledge of reaction kinetics and photochemistry as well as skill in using analytical instrumentation. This versatile experiment consists of two basic modules, three optional advanced modules, and additional add-ons that may be performed in various combinations to meet the unique learning objectives of general, analytical, physical, and environmental chemistry courses and science outreach activities. It may be performed as a traditional lab experiment or as an entirely remote exercise with an increased focus on data analysis and interpretation using provided example data sets. All of the photolysis experiments are carried out by preparing solutions of ranitidine or cimetidine in various matrices, irradiating the samples, and periodically removing subsamples for HPLC analysis of the compound of interest. Pseudo-first order kinetic plots are then generated to determine rate constants that are used to draw conclusions about photolysis pathways or to calculate additional kinetic parameters. In the two basic modules, cimetidine is found to degrade appreciably only when irradiated in the presence natural organic matter (NOM), indicating an indirect, photosensitized degradation pathway. In contrast, ranitidine degrades in pure buffer and in the presence of NOM with comparable rate constants, highlighting the predominant role of direct photolysis. In the advanced modules, students calculate ranitidine direct photolysis quantum yields and examine the significance of singlet oxygen as a photochemically produced reactive intermediate. The two basic modules may be completed in two 3 hour lab periods, while the advanced modules require additional time. This experiment requires only an HPLC instrument, inexpensive chemicals, and common glassware and lab equipment if performed in person and a personal computer if performed remotely.ISSN:0021-9584ISSN:1938-132
Observed smoking and tobacco pack display in Australian outdoor cafés 2 years after implementation of plain packaging
Neighborhood walkability, physical activity, and walking for transportation: A cross-sectional study of older adults living on low income
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Progression of Fatty Liver Disease in Children Receiving Standard of Care Lifestyle Advice
Background & aimsNonalcoholic fatty liver disease (NAFLD) is the most common pediatric chronic liver disease. Little is known about outcomes in recognized youth.MethodsWe compared paired liver biopsies from 122 of 139 children with NAFLD (74% male; 64% white; 71% Hispanic; mean age, 13 ± 3 years; age range, 8-17 years) who received placebo and standard of care lifestyle advice in 2 double-blind, randomized clinical trials within the nonalcoholic steatohepatitis (NASH) clinical research network from 2005 through 2015. We analyzed histologic changes with respect to baseline and longitudinal change in clinical variables using regression analysis.ResultsAt enrollment, 31% of the children had definite NASH, 34% had borderline zone 1 NASH, 13% had borderline zone 3 NASH, and 21% had fatty liver but not NASH. Over a mean period of 1.6 ± 0.4 years, borderline or definite NASH resolved in 29% of the children, whereas 18% of the children with fatty liver or borderline NASH developed definite NASH. Fibrosis improved in 34% of the children but worsened in 23%. Any progression to definite NASH and/or in fibrosis was associated with adolescent age, and higher waist circumference, levels of alanine or aspartate aminotransferase, total and low-density lipoprotein cholesterol at baseline (<0.05), and over follow-up time, with increasing level of alanine aminotransferase, hemoglobin A1C (P<.05), gamma-glutamyl transferase and development of type 2 diabetes (P<.01). Increasing level of gamma-glutamyl transferase was also associated with reduced odds of any improvement (P = .003).ConclusionsOne-third of children with NAFLD enrolled in placebo groups of clinical trials had histologic features of progression within 2 years, in association with increasing obesity and serum levels of aminotransferases and loss of glucose homeostasis