Concepts and software package for efficient quality control in targeted metabolomics studies - MeTaQuaC

Targeted quantitative mass spectrometry metabolite profiling is the workhorse of metabolomics research. Robust and reproducible data is essential for confidence in analytical results and is particularly important with large-scale studies. Commercial kits are now available which use carefully calibrated and validated internal and external standards to provide such reliability. However, they are still subject to processing and technical errors in their use and should be subject to a laboratory’s routine quality assurance and quality control measures to maintain confidence in the results. We discuss important systematic and random measurement errors when using these kits and suggest measures to detect and quantify them. We demonstrate how wider analysis of the entire dataset, alongside standard analyses of quality control samples can be used to identify outliers and quantify systematic trends in order to improve downstream analysis. Finally we present the MeTaQuaC software which implements the above concepts and methods for Biocrates kits and creates a comprehensive quality control report containing rich visualization and informative scores and summary statistics. Preliminary unsupervised multivariate analysis methods are also included to provide rapid insight into study variables and groups. MeTaQuaC is provided as an open source R package under a permissive MIT license and includes detailed user documentation

Serum Starvation Accelerates Intracellular Metabolism in Endothelial Cells

Periods of low energy supply are challenging conditions for organisms and cells during fasting or famine. Although changes in nutrient levels in the blood are first sensed by endothelial cells, studies on their metabolic adaptations to diminished energy supply are lacking. We analyzed the dynamic metabolic activity of human umbilical vein endothelial cells (HUVECs) in basal conditions and after serum starvation. Metabolites of glycolysis, the tricarboxylic acid (TCA) cycle, and the glycerol pathway showed lower levels after serum starvation, whereas amino acids had increased levels. A metabolic flux analysis with 13C-glucose or 13C-glutamine labeling for different time points reached a plateau phase of incorporation after 30 h for 13C-glucose and after 8 h for 13C-glutamine under both experimental conditions. Notably, we observed a faster label incorporation for both 13C-glucose and 13C-glutamine after serum starvation. In the linear range of label incorporation after 3 h, we found a significantly faster incorporation of central carbon metabolites after serum starvation compared to the basal state. These findings may indicate that endothelial cells develop increased metabolic activity to cope with energy deficiency. Physiologically, it can be a prerequisite for endothelial cells to form new blood vessels under unfavorable conditions during the process of angiogenesis in vivo

The effects of organizational politics on employee motivations to participate in target setting and employee budgetary participation

© 2018 Elsevier Inc. This research investigates if and how organizational politics affects budgetary participation. It also ascertains if different forms of organizational politics have different effects on budgetary participation. Three forms of organizational politics (going along to get ahead; pay and promotion policies; and general political behavior) are examined. Based on a survey sample of subordinates with managerial responsibilities, the PLS results indicate as follows. As general political behavior is engaged in by the superiors and not the subordinates, its effects on budgetary participation are direct and not attributable to the subordinates’ motivations to participate in target setting. In contrast, as the politics of going along to get ahead is engaged in by the subordinates themselves, its effects on budgetary participation are indirect and via the subordinates’ motivations to participate in target setting. The effects of the politics of pay and promotion policies on budgetary participation are unclear. These results highlight not only the relevance of organizational politics in budgeting, but they also direct attention to where the management of such politics is needed to influence the extent of budgetary participation