Project description:Brown1997 - Plasma Melatonin Levels A mathematical model that incorporates a piecewise function for NAT activity to predict melatonin concentration. This model is described in the article: A mathematical model of diurnal variations in human plasma melatonin levels. Brown EN, Choe Y, Shanahan TL, Czeisler CA. Am. J. Physiol. 1997 Mar; 272(3 Pt 1): E506-16 Abstract: Studies in animals and humans suggest that the diurnal pattern in plasma melatonin levels is due to the hormone's rates of synthesis, circulatory infusion and clearance, circadian control of synthesis onset and offset, environmental lighting conditions, and error in the melatonin immunoassay. A two-dimensional linear differential equation model of the hormone is formulated and is used to analyze plasma melatonin levels in 18 normal healthy male subjects during a constant routine. Recently developed Bayesian statistical procedures are used to incorporate correctly the magnitude of the immunoassay error into the analysis. The estimated parameters [median (range)] were clearance half-life of 23.67 (14.79-59.93) min, synthesis onset time of 2206 (1940-0029), synthesis offset time of 0621 (0246-0817), and maximum N-acetyltransferase activity of 7.17(2.34-17.93) pmol x l(-1) x min(-1). All were in good agreement with values from previous reports. The difference between synthesis offset time and the phase of the core temperature minimum was 1 h 15 min (-4 h 38 min-2 h 43 min). The correlation between synthesis onset and the dim light melatonin onset was 0.93. Our model provides a more physiologically plausible estimate of the melatonin synthesis onset time than that given by the dim light melatonin onset and the first reliable means of estimating the phase of synthesis offset. Our analysis shows that the circadian and pharmacokinetics parameters of melatonin can be reliably estimated from a single model. This model is hosted on BioModels Database and identified by: BIOMD0000000672. To cite BioModels Database, please use: Chelliah V et al. BioModels: ten-year anniversary. Nucl. Acids Res. 2015, 43(Database issue):D542-8. To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information.

Project description:Background: Diclofenac is a non-steroidal anti-inflammatory drug frequently found in the aquatic environment. Previous studies have reported histological changes in the liver, kidney and gills of fish at concentrations similar to those measured in treated sewage effluents (~1 µg/L). Analyses or predictions of blood plasma levels in fish allow a direct comparison with human therapeutic plasma levels, and may therefore be used to indicate a risk for pharmacological effects in fish. To relate internal exposure to a pharmacological interaction we therefore investigated global hepatic gene expression together with bioconcentration to blood plasma and liver of rainbow trout (Oncorhynchus mykiss) exposed to waterborne diclofenac. Results: At the highest exposure (81.5µg/L) the fish plasma concentration reached ~88% of the human therapeutic levels (Cmax) after two weeks. Using an oligonucleotide microarray followed by quantitative PCR we found extensive effects on hepatic gene expression at this concentration, and some genes were regulated down to the lowest concentration tested (1.6 µg/L) corresponding to ~1.5% of the human Cmax. Functional analysis of differentially expressed genes revealed effects on biological processes such as inflammation and immune response, in agreement with the expected mode of action of diclofenac. In contrast to some previously reported results, the bioconcentration factor was found to be stable (4.02±0.75 for blood plasma and 2.54±0.36 for liver) regardless of the water concentration. Conclusions: Hepatic gene expression is affected in fish at blood levels similar to and below the human Cmax. This adds confidence to the use of fish blood plasma levels to predict risks for pharmacological responses in fish. The microarray results indicate similarities in the mode of action of diclofenac between humans and fish. The identified set of regulated genes may contain useful exposure biomarkers to be used in complex exposure scenarios.

Project description:Background---For decades, plasma lipid levels have been known risk factors of atherosclerosis. Recently, inflammation has gained acceptance as a crucial event in the pathogenesis and development of atherosclerosis. A number of studies have provided some insights into the relationships between the two aspects of atherosclerosis: plasma lipids --- the risk factors, and circulating leukocytes --- the effectors of inflammation. In this study, we investigate the relationships between plasma lipids and leukocytes. Methods and Results---No significant correlation was found between leukocyte counts and plasma lipid levels in 74 individuals. Profiling and analyzing the leukocyte gene expression of 32 individuals revealed distinctive patterns in response to plasma lipid levels: 1) genes involved in lipid metabolism and in the electron transport chain were positively correlated with triglycerides and low-density lipoprotein cholesterol levels, and negatively correlated with high-density lipoprotein cholesterol levels; 2) genes involved in platelet activation were negatively correlated with high-density lipoprotein cholesterol levels; 3) transcription factors regulating lipidgenesis-related genes were correlated with plasma lipid levels; 4) a number of genes correlated to plasma lipid levels were found located in the regions of known QTLs associated with hyperlipemia. Conclusions--- We discovered interesting patterns of leukocyte gene expression in response to plasma lipid levels. Most importantly, genes involved in lipid metabolism, the electron transportation chain, and platelet activation were found correlated with plasma lipid levels. We suggest that leukocytes respond to changing plasma lipid levels by regulating a network of genes, including genes involved in lipid and fatty acid metabolism, through the activation of key transcription factors, such as sterol regulatory element binding transcription factors and peroxisome proliferative activated receptors. Keywords: Atherosclerosis, leukocyte, lipid, gene expression

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