Fabian Kirchhoff

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BACKGROUND The goal of this study was to develop and to validate an improved isotope-dilution-liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification of methylmalonic acid (MMA) in urine. METHODS A previously described sample preparation protocol requires two solvent extraction steps, including evaporation. The first(More)
OBJECTIVE Glucocorticoids play a major role in the consolidation and retrieval of traumatic information. They act through the glucocorticoid receptor, for which, in humans, several polymorphisms have been described. In particular, the BclI single-nucleotide polymorphism is associated with hypersensitivity to glucocorticoids and with susceptibility to(More)
BACKGROUND LC-MS/MS is an almost universal technology for the quantification of small molecules in human sample materials. The widespread use of this technology in laboratory medicine is so far limited mainly by the extensive occupation of highly trained personnel which is required for method implementation and application. Furthermore, robustness of(More)
OBJECTIVES Only unbound serum cortisol is bioactive and protein binding of cortisol is highly variable. Thus, the quantification of free serum cortisol (FSC) is of superior biological relevance compared to total serum cortisol quantification. Consequently, the development of automated routine tests for FSC for endocrine testing is desirable - along the(More)
AIM Music might benefit preterm infants in stressful, intensive care environments. However, data on stress level indicators, determined by salivary cortisol levels, are scarce. We evaluated the effect of live harp music on the stress level indicators of preterm infants in a neonatal intensive care unit (NICU). METHODS We exposed 20 stable preterm infants(More)
The aim of our study was to test an alternative principle of signal normalisation in LC-MS/MS. During analyses, post column infusion of the target analyte is done via a T-piece, generating an "area under the analyte peak" (AUP). The ratio of peak area to AUP is assessed as assay response. Acceptable analytical performance of this principle was found for an(More)
BACKGROUND Extensive sets of data are required to investigate the potential use of a therapeutic drug monitoring with individualization of dosage of the antimycotic compound caspofungin. The goal was to develop an improved liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for this aim. METHODS Following protein precipitation, on-line solid(More)
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