Isotope dilution-liquid chromatography-tandem mass spectrometry-based candidate reference measurement procedures for the quantification of 24,25-dihydroxyvitamin D2 and 24,25-dihydroxyvitamin D3 in human serum and plasma.

Objectives: Isotope dilution-liquid chromatography-tandem mass spectrometry (ID-LC MS/MS)-based candidate reference measurement procedures (RMPs) for the quantification of 24,25(OH)D2 and 24,25(OH)D3 in human serum and plasma are presented.

Methods: Quantitative nuclear magnetic resonance (qNMR) spectroscopic methodology was utilized to assign absolute content (g/g) and SI-traceability to reference materials used as primary calibrators. For liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis a two-dimensional heart cut LC approach, in combination with a supported liquid extraction protocol, was established to mitigate matrix effects and prevent co-elution of interferences.

An isotope dilution-liquid chromatography-tandem mass spectrometry-based candidate reference measurement procedure for the quantification of cortisol in human serum and plasma.

Objectives: Accurate measurement of serum cortisol is crucial for the diagnosis and management of adrenal disorders. Thus, we have developed a novel isotope dilution-liquid chromatography-tandem mass spectrometry (ID-LC MS/MS)-based candidate reference measurement procedure (RMP) to quantify cortisol in human serum/plasma, offering higher sensitivity and reliability compared to existing RMPs.

Methods: Quantitative Nuclear Magnetic Resonance spectroscopic (qNMR) methodology has been utilized to assign the absolute content (g/g) and SI-traceability to the reference materials.

The anti-microbial peptide LL-37 inhibits the activation of dendritic cells by TLR ligands.

The endogenous anti-microbial peptide LL-37/hCAP-18 is an effector molecule of the innate host defense system at surfaces of the body. Besides its direct anti-microbial activity, the peptide interacts with different cell types. Dendritic cells (DCs) play a central role in mucosal host defense.

Allergic airway inflammation inhibits pulmonary antibacterial host defense.

The innate immune system of the lung is a multicomponent host defense system and in addition has an instructing role in regulating the quality and quantity of the adaptive immune response. When the interaction between innate and adaptive immunity is disturbed, pathological conditions such as asthma can develop. It was the aim of the study to investigate the effect of the allergic inflammation of the lung on the innate host defense during bacterial infection.

Human endogenous antibiotic LL-37 stimulates airway epithelial cell proliferation and wound closure.

Antimicrobial peptides are endogenous antibiotics that directly inactivate microorganisms and in addition have a variety of receptor-mediated functions. LL-37/hCAP-18 is the only cathelicidin found in humans and is involved in angiogenesis and regulation of the innate immune system. The aim of the present study was to characterize the role of the peptide LL-37 in the regulation of wound closure of the airway epithelium in the cell line NCI-H292 and primary airway epithelial cells.