Cryogenic probe technology enables multidimensional solid-state NMR of the stratum corneum without isotope labeling.

Solid-state NMR has great potential for investigating molecular structure, dynamics, and organization of the stratum corneum, the outer 10-20 μm of the skin, but is hampered by the unfeasibility of isotope labelling as generally required to reach sufficient signal-to-noise ratio for the more informative multidimensional NMR techniques. In this preliminary study of pig stratum corneum at 35 °C and water-free conditions, we demonstrate that cryogenic probe technology offers sufficient signal boost to observe previously undetectable minor resonances that can be uniquely assigned to fluid cholesterol, ceramides, and triacylglycerols, as well as enables H-H spin diffusion monitored by 2D H-C HETCOR to estimate 1-100 nm distances between specific atomic sites on proteins and lipids. The new capabilities open up for future multidimensional solid-state NMR studies to answer long-standing questions about partitioning of additives, such as pharmaceutically active substances, between solid and liquid domains within the protein and lipid phases in the stratum corneum and the lipids of the sebum.

Molecular Mobility in Keratin-Rich Materials Monitored by Nuclear Magnetic Resonance: A Tool for the Evaluation of Structure-Giving Properties.

Keratins are structural proteins that are abundant in human skin, nails, and hair, where they provide mechanical strength. In the present study, we investigate the molecular mobilities and structures of three keratin-rich materials with clearly different mechanical properties: nails, stratum corneum (upper layer of epidermis), and keratinocytes (from lower layer of epidermis). We use solid-state NMR on natural-abundance C to characterize small changes in molecular dynamics in these biological materials with close to atomistic resolution.

The effects of glycols on molecular mobility, structure, and permeability in stratum corneum.

The skin provides an attractive alternative to the conventional drug administration routes. Still, it comes with challenges as the upper layer of the skin, the stratum corneum (SC), provides an efficient barrier against permeation of most compounds. One way to overcome the skin barrier is to apply chemical permeation enhancers, which can modify the SC structure.

Extraction of natural moisturizing factor from the stratum corneum and its implication on skin molecular mobility.

The natural moisturizing factor (NMF) is a mixture of small water-soluble compounds present in the upper layer of the skin, stratum corneum (SC). Soaking of SC in water leads to extraction of the NMF molecules, which may influence the SC molecular properties and lead to brittle and dry skin. In this study, we investigate how the molecular dynamics in SC lipid and protein components are affected by the removal of the NMF compounds.

On the interference of urea with CO/CO chemistry of cellulose model solutions in NaOH(aq).

The CO/CO chemistry of the cellulose/NaOH(aq) solutions has been recently reported to comprise a CO incorporation through formation of a transient cellulose carbonate intermediate along with cellulose - CO interactions. This work explores on molecular interactions arising when this chemistry is brought together with urea, the most common stabiliser of these solutions. H, C and steady-state heteronuclear Overhauser effect NMR studies on the cellulose analogues (methyl-β-glucopyranoside (β-MeO-Glcp) and microcrystalline cellulose), combined with pH and ATR-FTIR measurements, reveal concurrent interactions of urea with both CO and CO- leading to increased uptake of CO and a buffering effect.

In primary health care, never prescribe antibiotics to patients suspected of having an uncomplicated sore throat caused by group A beta-haemolytic streptococci without first confirming the presence of this bacterium.

Background: There are several consensus-describing decision rules for patients in primary health care with a sore throat. The objective of this study was to estimate the number of unnecessary antibiotic prescriptions in primary health care given to patients with a sore throat, due to these different decision rules. A further aim was to suggest revised rules for decision-making in primary health care, when a sore throat caused by group A beta-haemolytic streptococci (GAS) is suspected.