Hydrophilic interaction electrochromatography applied in packed capillaries

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Improving the performance of contemporary packed and open-tubular capillary electrochromatography

Capillary electrochromatography (CEC) has been described as a highly efficient separation technique. However, after more then twenty years of research, industrial implementation is still not been reported. Restrictions in column technology and the limited robustness of the instrumentation hampered the evolution of CEC. In this thesis, kinetic plots for CEC is developed as a tool to evaluate the performance of contempoary commercial CEC and for the evaluation of new strategies to develop stationary phases in CEC

Community Reference Laboratory for Feed Additives Authorisation: Annual Report 2006

The objective of this report is to present the activities of the Community Reference Laboratory for Feed Additives Authorisation in 2006 (CRL-FAA). The report shows that besides the evaluation of dossiers, the CRL-FAA carried out many other tasks. Important additional matters were the successful accreditation of the laboratory according to ISO 17025, the support of the European Commission regarding the drafting of the new guidelines for the applicants, further improvement of informatics tools and the organisation of two workshops to discuss these topics with the National Reference Laboratory.JRC.D.8-Food safety and qualit

Cholesterol-sensing liver X receptors stimulate Th2-driven allergic eosinophilic asthma in mice

Introduction: Liver X receptors (LXRs) are nuclear receptors that function as cholesterol sensors and regulate cholesterol homeostasis. High cholesterol has been recognized as a risk factor in asthma; however, the mechanism of this linkage is not known. Methods: To explore the importance of cholesterol homeostasis for asthma, we investigated the contribution of LXR activity in an ovalbumin- and a house dust mite-driven eosinophilic asthma mouse model. Results: In both models, airway inflammation, airway hyper-reactivity, and goblet cell hyperplasia were reduced in mice deficient for both LXR and LXR isoforms (LXR-/--/-) as compared to wild-type mice. Inversely, treatment with the LXR agonist GW3965 showed increased eosinophilic airway inflammation. LXR activity contributed to airway inflammation through promotion of type 2 cytokine production as LXR-/--/- mice showed strongly reduced protein levels of IL-5 and IL-13 in the lungs as well as reduced expression of these cytokines by CD4(+) lung cells and lung-draining lymph node cells. In line herewith, LXR activation resulted in increased type 2 cytokine production by the lung-draining lymph node cells. Conclusions: In conclusion, our study demonstrates that the cholesterol regulator LXR acts as a positive regulator of eosinophilic asthma in mice, contributing to airway inflammation through regulation of type 2 cytokine production

Comprehensive two-dimensional liquid chromatography coupled to the ABTS radical scavenging assay: a powerful method for the analysis of phenolic antioxidants

The on-line combination of comprehensive two-dimensional liquid chromatography (LC x LC) with the 2,2'-azino-bis(3-ethylbenzothiazoline)-6 sulphonic acid (ABTS) radical scavenging assay was investigated as a powerful method to determine the free radical scavenging activities of individual phenolics in natural products. The combination of hydrophilic interaction chromatography (HILIC) separation according to polarity and reversed-phase liquid chromatography (RP-LC) separation according to hydrophobicity is shown to provide much higher resolving power than one-dimensional separations, which, combined with on-line ABTS detection, allows the detailed characterisation of antioxidants in complex samples. Careful optimisation of the ABTS reaction conditions was required to maintain the chromatographic separation in the antioxidant detection process. Both on-line and off-line HILIC x RP-LC-ABTS methods were developed, with the former offering higher throughput and the latter higher resolution. Even for the fast analyses used in the second dimension of on-line HILIC x RP-LC, good performance for the ABTS assay was obtained. The combination of LC x LC separation with an on-line radical scavenging assay increases the likelihood of identifying individual radical scavenging species compared to conventional LC-ABTS assays. The applicability of the approach was demonstrated for cocoa, red grape seed and green tea phenolics