Insights From Liver-Humanized Mice on Cholesterol Lipoprotein Metabolism and LXR-Agonist Pharmacodynamics in Humans

Background and Aims Genetically modified mice have been used extensively to study human disease. However, the data gained are not always translatable to humans because of major species differences. Liver-humanized mice (LHM) are considered a promising model to study human hepatic and systemic metabolism. Therefore, we aimed to further explore their lipoprotein metabolism and to characterize key hepatic species-related, physiological differences. Approach and Results Fah(-/-), Rag2(-/-), and Il2rg(-/-) knockout mice on the nonobese diabetic (FRGN) background were repopulated with primary human hepatocytes from different donors. Cholesterol lipoprotein profiles of LHM showed a human-like pattern, characterized by a high ratio of low-density lipoprotein to high-density lipoprotein, and dependency on the human donor. This pattern was determined by a higher level of apolipoprotein B100 in circulation, as a result of lower hepatic mRNA editing and low-density lipoprotein receptor expression, and higher levels of circulating proprotein convertase subtilisin/kexin type 9. As a consequence, LHM lipoproteins bind to human aortic proteoglycans in a pattern similar to human lipoproteins. Unexpectedly, cholesteryl ester transfer protein was not required to determine the human-like cholesterol lipoprotein profile. Moreover, LHM treated with GW3965 mimicked the negative lipid outcomes of the first human trial of liver X receptor stimulation (i.e., a dramatic increase of cholesterol and triglycerides in circulation). Innovatively, LHM allowed the characterization of these effects at a molecular level. Conclusions LHM represent an interesting translatable model of human hepatic and lipoprotein metabolism. Because several metabolic parameters displayed donor dependency, LHM may also be used in studies for personalized medicine.Peer reviewe

Theoretical and empirical examination of decentralized environmental regulation

This dissertation closely examines the merits, weaknesses, and potential of decentralized environmental regulation. I examine three areas of particular concern in the structure of environmental regulation. In the first chapter, I examine how information problems resulting from incorrectly specified atmospheric models are likely to affect economic efficiency in a permit market. While permit markets have been heralded as a promising solution for controlling environmentally damaging emissions, there is no formal research linking the atmospheric model, which directly affects permit prices, with economic outcomes. In the chapter, I develop a generalized theoretical model that demonstrates the problems that are likely to arise when there is uncertainty in the underlying atmospheric parameter estimates. As it turns out, permit markets operating with incorrectly specified atmospheric models may result in large losses in economic efficiency, even if the permit market is operating ideally in an economic sense. The second chapter analyzes a much broader issue, that of state versus federal environmental regulation. The chapter focuses on the methods used by states attempting to control interstate water pollution in the Ohio Valley in the early 1900s. The time period was chosen to predate federal intervention into environmental regulation and, hence, allows for a clean test of how states might be expected to address difficult pollution problems under a system of state regulation. Using a simple game theoretic model, the paper explores interstate water pollution control compacts and their uses in addressing interstate water pollution. I find that states were able to overcome significant bargaining difficulties in formulating the compacts, which ultimately led to effective control of interstate water pollution. The final chapter focuses on voluntary overcompliance by firms facing environmental standards. The paper models environmental regulation according to the EPA's Best Available Control Technology (BACT). The model predicts voluntary overcompliance by firms as they attempt to raise the (endogenous) environmental standard and, in the process, raise their rivals' costs. The paper also demonstrates the merits of nonuniform environmental standards. In attempting to elicit efficient levels of R&D investment, the regulatory authority may discourage socially wasteful overinvestment in pollution technology through the use of nonuniform standards.hydrology collectio

The microstructural record of porphyroclasts and matrix of partly serpentinized peridotite mylonites – from brittle and crystal-plastic deformation to dissolution–precipitation creep

We present microfabrics in high-pressure, metamorphic, partly serpentinized peridotite mylonites from the Voltri Massif, in which porphyroclasts and matrix record independent deformation events. The microfabrics are analysed using polarization microscopy and electron microscopy (SEM/EBSD, EMP). The mylonites contain diopside and olivine porphyroclasts originating from the mantle protolith embedded in a fine-grained matrix consisting mainly of antigorite and minor olivine and pyroxene. The porphyroclasts record brittle and crystal-plastic deformation of the peridotite at upper-mantle conditions and differential stresses of a few hundred MPa. After the peridotites became serpentinized, deformation occurred mainly by dissolution–precipitation creep resulting in a pronounced foliation of the antigorite matrix, crenulation cleavages and newly precipitated olivine and pyroxene from the pore fluid at sites of dilation, i.e. in strain shadows next to porphyroclasts and folded fine-grained antigorite layers. Antigorite reveals a pronounced associated shape preferred orientation (SPO) and crystallographic preferred orientation (CPO) with the basal (001) cleavage plane oriented in the foliation plane. In monomineralic antigorite aggregates at sites of stress concentration around porphyroclasts, a characteristically reduced grain size and deflecting CPO as well as sutured grain boundaries indicate also some contribution of crystal-plastic deformation and grain-boundary migration of antigorite. In contrast, the absence of any intragranular deformation features in newly precipitated olivine in strain shadows reveals that stresses were not sufficiently high to allow for significant dislocation creep of olivine at conditions at which antigorite is stable. The porphyroclast microstructures are not associated with the microstructures of the mylonitic matrix, but are inherited from an independent earlier deformation. The porphyroclasts record a high-stress deformation of the peridotite with dislocation creep of olivine in the upper mantle probably related to rifting processes, whereas the serpentinite matrix records dominantly dissolution–precipitation creep and low stresses during subduction and exhumation

Extensive double humanization of both liver and hematopoiesis in FRGN mice

Preclinical research in animals often fails to adequately predict the outcomes observed in human patients. Chimeric animals bearing individual human tissues have been developed to provide improved models of human-specific cellular processes. Mice transplanted with human hematopoietic stem cells can be used to study human immune responses, infections of blood cells and processes of hematopoiesis. Animals with humanized livers are useful for modeling hepatotropic infections as well as drug metabolism and hepatotoxicity. However, many pathophysiologic processes involve both the liver and the hematolymphoid system. Examples include hepatitis C/HIV co-infection, immune mediated liver diseases, liver injuries with inflammation such as steatohepatitis and alcoholic liver disease. We developed a robust protocol enabling the concurrent double-humanization of mice with mature hepatocytes and human blood. Immune-deficient, fumarylacetoacetate hydrolase (Fah−/−), Rag2−/− and Il2rg−/− deficient animals on the NOD-strain background (FRGN) were simultaneously co-transplanted with adult human hepatocytes and hematopoietic stem cells after busulfan and Ad:uPA pre-conditioning. Four months after transplantation the average human liver repopulation exceeded 80% and hematopoietic chimerism also was high (40–80% in bone marrow). Importantly, human macrophages (Kupffer cells) were present in the chimeric livers. Double-chimeric FRGN mice will serve as a new model for disease processes that involve interactions between hepatocytes and hematolymphoid cells

Prototyping connected devices for the internet of things

Tools like Microsoft.NET Gadgeteer offer the ability to quickly prototype, test, and deploy connected devices, providing a key element that will accelerate our understanding of the challenges in realizing the Internet of Things vision. © 1970-2012 IEEE

The pharmacokinetics and metabolism of diclofenac in chimeric humanized and murinized FRG mice

The pharmacokinetics of diclofenac were investigated following single oral doses of 10 mg/kg to chimeric liver humanized and murinized FRG and C57BL/6 mice. In addition, the metabolism and excretion were investigated in chimeric liver humanized and murinized FRG mice. Diclofenac reached maximum blood concentrations of 2.43 ± 0.9 µg/mL (n = 3) at 0.25 h post-dose with an AUCinf of 3.67 µg h/mL and an effective half-life of 0.86 h (n = 2). In the murinized animals, maximum blood concentrations were determined as 3.86 ± 2.31 µg/mL at 0.25 h post-dose with an AUCinf of 4.94 ± 2.93 µg h/mL and a half-life of 0.52 ± 0.03 h (n = 3). In C57BL/6J mice, mean peak blood concentrations of 2.31 ± 0.53 µg/mL were seen 0.25 h post-dose with a mean AUCinf of 2.10 ± 0.49 µg h/mL and a half-life of 0.51 ± 0.49 h (n = 3). Analysis of blood indicated only trace quantities of drug-related material in chimeric humanized and murinized FRG mice. Metabolic profiling of urine, bile and faecal extracts revealed a complex pattern of metabolites for both humanized and murinized animals with, in addition to unchanged parent drug, a variety of hydroxylated and conjugated metabolites detected. The profiles in humanized mice were different to those of both murinized and wild-type animals, e.g., a higher proportion of the dose was detected in the form of acyl glucuronide metabolites and much reduced amounts as taurine conjugates. Comparison of the metabolic profiles obtained from the present study with previously published data from C57BL/6J mice and humans revealed a greater, though not complete, match between chimeric humanized mice and humans, such that the liver humanized FRG model may represent a model for assessing the biotransformation of such compounds in humans