Nanoscale alterations of corneocytes indicate skin disease.

BACKGROUND: The skin barrier protects the organism against exogenous stressors and simultaneously prevents excessive water loss. While the delicate regulation of skin barrier is not completely understood, morphological and histological evaluation remain key features of clinical investigations. Here, we extended the phenotypic perspective down to the nanoscale. METHODS: Corneocyte samples were obtained non-invasively by a standard tape stripping procedure from 21 indviduals. Scanning electron (SEM) and atomic force microcopy (AFM) were used to record nanoscale topography. Circular nano-objects were identified and these were quantitated through computer vision. RESULTS: Typical dimensions of 273 nm height and 305 nm width. We showed that their density does not correlate to age or pigmentation in healthy subjects, but that they were clearly elevated in corneocytes from patients with atopic dermatitis, a common inflammatory skin condition. CONCLUSION: The presence of these corneocyte-nanostructures might be used as a diagnostic parameter for skin disorders - even in cases below a clinical threshold.

Study of the stability of polymyxins B(1), E(1) and E(2) in aqueous solution using liquid chromatography and mass spectrometry.

Polymyxins B(1), E(1) (colistin A) and E(2) (colistin B) were subjected to degradation in aqueous solutions of different pH values (1.4, 3.4, 5.4 and 7.4) and at different temperatures (37, 50 and 60 degrees C) in order to investigate the characteristics of decomposition. The progress of decomposition was followed by reversed-phase liquid chromatography on YMC-Pack Pro, C-18 stationary phase. The degradation curves showed (pseudo) first order kinetics. The pH-rate profiles indicate that colistin is more susceptible to degradation in solutions of pH above 5 and is more stable in acidic media. The degradation of polymyxin B(1) was most rapid at pH 7.4. Qualitative analysis of the degradation products by LC/MS reveals that racemization is the major mechanism of degradation in both acidic and neutral media.