University of Kansas

About: University of Kansas is a education organization based out in Lawrence, Kansas, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 38183 authors who have published 81381 publications receiving 2986312 citations. The organization is also known as: KU & Univ of Kansas.

Eutrophication of freshwater and marine ecosystems

Abstract: Initial understanding of the links between nutrients and aquatic productivity originated in Europe in the early 1900s, and our knowledge base has expanded greatly during the past 40 yr. This explosion of eutrophication-related research has made it unequivocally clear that a comprehensive strategy to prevent excessive amounts of nitrogen and phosphorus from entering our waterways is needed to protect our lakes, rivers, and coasts from water quality deterioration. However, despite these very significant advances, cultural eutrophication remains one of the foremost problems for protecting our valuable surface water resources. The papers in this special issue provide a valuable cross section and synthesis of our current understanding of both freshwater and marine eutrophication science. They also serve to identify gaps in our knowledge and will help to guide future research. Knowledge of the links between nutrients and aquatic productivity began with the pioneering work of Weber (1907) on German peat bogs and with Johnstone’s (1908) studies of the North Sea. A crystallization of freshwater eutrophication concepts took place soon thereafter in Northern Europe, where the first trophic classification systems for surface waters were developed. These early classification systems were based on the intensity of aquatic organic matter production, as well as nutrient supply conditions and ecosystemlevel consequences of increased production (e.g., hypolimnetic oxygen depletion; Rodhe 1969). There was a lot of uncertainty in the subsequent 50 yr about the physical, chemical, and ecological details of the eutrophication process, and hot debates raged about the relative roles of different mineral nutrients as constraints on, or regulators of, primary productivity, especially the macronutrients nitrogen (N), phosphorus (P), and carbon (C). Work on the eutrophication process accelerated in the 1960s and 1970s. Particularly important was the landmark 1971 American Society of Limnology and Oceanography (ASLO) eutrophication symposium that culminated in the publication of the first special issue of Limnology and Oceanography (L&O) on nutrients and eutrophication, edited by G. E. Likens (Likens 1972a). This special issue was similarly stimulated by a symposium that the three of us 1

The mechanism underlying acetaminophen-induced hepatotoxicity in humans and mice involves mitochondrial damage and nuclear DNA fragmentation.

Abstract: Acetaminophen (APAP) overdose is the predominant cause of acute liver failure in the United States. Toxicity begins with a reactive metabolite that binds to proteins. In rodents, this leads to mitochondrial dysfunction and nuclear DNA fragmentation, resulting in necrotic cell death. While APAP metabolism is similar in humans, the later events resulting in toxicity have not been investigated in patients. In this study, levels of biomarkers of mitochondrial damage (glutamate dehydrogenase [GDH] and mitochondrial DNA [mtDNA]) and nuclear DNA fragments were measured in plasma from APAP-overdose patients. Overdose patients with no or minimal hepatic injury who had normal liver function tests (LTs) (referred to herein as the normal LT group) and healthy volunteers served as controls. Peak GDH activity and mtDNA concentration were increased in plasma from patients with abnormal LT. Peak nuclear DNA fragmentation in the abnormal LT cohort was also increased over that of controls. Parallel studies in mice revealed that these plasma biomarkers correlated well with tissue injury. Caspase-3 activity and cleaved caspase-3 were not detectable in plasma from overdose patients or mice, but were elevated after TNF-induced apoptosis, indicating that APAP overdose does not cause apoptosis. Thus, our results suggest that mitochondrial damage and nuclear DNA fragmentation are likely to be critical events in APAP hepatotoxicity in humans, resulting in necrotic cell death.

Mediation models for longitudinal data in developmental research.

Abstract: Mediation models are used to describe the mechanism(s) by which one variable influences another. These models can be useful in developmental research to explicate the relationship between variables, developmental processes, or combinations of variables and processes. In this article we describe aspects of mediation effects specific to developmental research. We focus on three central issues in longitudinal mediation models: the theory of change for variables in the model, the role of time in the model, and the types of indirect effects in the model. We use these themes as we describe three different models for examining mediation in longitudinal data.