The importance of 12R-lipoxygenase and transglutaminase activities in the hydration-dependent ex vivo maturation of corneocyte envelopes

Background Terminally differentiated keratinocytes acquire corneocyte protein envelopes (CPE) complexed with corneocyte lipid envelopes (CLE). These two structural components of the corneocyte envelopes (CE) undergo maturation by gaining in hydrophobicity, rigidity and surface area. Linoleoyl acylceramides are processed by 12R‐lipoxygenase (12R‐LOX) and other enzymes before transglutaminase (TG) attaches ω‐hydroxyceramides to involucrin in the CPE. Concurrently, structural proteins are cross‐linked by TG that has been activated by cathepsin D (CathD). Objectives The primary aim of this work was to demonstrate the impact of relative humidity (RH) during ex vivo CE maturation. Low, optimal and high RH were selected to investigate the effect of protease inhibitors (PI) on CE maturation and TG activity; in addition, 12R‐LOX and CathD activity were measured at optimal RH. Finally, the effect of glycerol on ex vivo CE maturation was tested at low, optimal and high RH. Methods The first and ninth tape strip of photo‐exposed (PE) cheek and photo‐protected (PP) post auricular sites of healthy volunteers were selected. Ex vivo CE maturation was assessed via the Relative CE Maturity (RCEM) approach based on CE rigidity and hydrophobicity. The second and eighth tapes were exposed to RH in presence of inhibitors. Results Irrespective of tape stripping depth, CEs from PE samples attained CE rigidity to the same extent as mature CEs from the PP site, but such improvement was lacking for CE hydrophobicity. 70% RH was optimal for ex vivo CE maturation. The inhibition of 12R‐LOX activity resulted in enhanced CE rigidity which was reduced by the TG inhibitor. CE hydrophobicity remained unchanged during ex vivo maturation in the presence of TG or 12R‐LOX inhibition. CE hydrophobicity was enhanced in the presence of glycerol at 44% RH and 100% RH but not at 70% RH. Furthermore, TG activity was significantly diminished at 100% Rh compared to the commercial inhibitor LDN‐27219. However, a protease inhibitor mix reversed the negative effect of over hydration. Conclusion The study adds to the understanding of the roles of 12R‐LOX and TG activity in CE maturation, and gives further insight into the effect of glycerol on the SC

A general dissipativity constraint for feedback system design, with emphasis on MPC

A ‘General Dissipativity Constraint’ (GDC) is introduced to facilitate the design of stable feedback systems. A primary application is to MPC controllers when it is preferred to avoid the use of ‘stabilising ingredients’ such as terminal constraint sets or long prediction horizons. Some very general convergence results are proved under mild conditions. The use of quadratic functions, replacing GDC by ‘Quadratic Dissipation Constraint’ (QDC), is introduced to allow implementation using linear matrix inequalities. The use of QDC is illustrated for several scenarios: state feedback for a linear time-invariant system, MPC of a linear system, MPC of an input-affine system, and MPC with persistent disturbances. The stability that is guaranteed by GDC is weaker than Lyapunov stability, being ‘Lagrange stability plus convergence’. Input-to-state stability is obtained if the control law is continuous in the state. An example involving an open-loop unstable helicopter illustrates the efficacy of the approach in practice.National Research Foundation Singapor

Effect of different alcohols on stratum corneum kallikrein 5 and phospholipase A2 together with epidermal keratinocytes and skin irritation

OBJECTIVES: The aim of this exploratory study was to investigate the effect of ethanol, isopropanol and n-propanol on stratum corneum (SC) enzymes and keratinocytes in vitro together with their effects on skin condition and function. METHODS: Activities of kallikrein 5 (KLK5) and phospholipase A2 (PLA2) as well as keratinocyte metabolic activity, interleukin-1α (IL-1α) and tumor necrosis factor-α (TNF-α) were measured in vitro in the presence and absence of the different alcohols. We also measured transepidermal water loss (TEWL), skin capacitance, visual dryness and visual redness on the volar forearms of 25 Caucasian women following application of the alcohols 20 and 100 times per day over a period of 14 days in a clinical study. RESULTS: Reduced activities of KLK5 and PLA2 were observed in the presence of the alcohols. The greatest denaturing effect was always observed for n-propanol (P  isopropanol > ethanol. At the high application frequencies, the effect of the different alcohols on transepidermal water loss (TEWL) and skin capacitance was similar, but at the low application frequencies, n-propanol had a significant effect on TEWL and capacitance values (P < 0.05). Equally, n-propanol and isopropanol produced significantly more skin redness at the low application frequencies. CONCLUSIONS: Clearly, isopropanol and n-propanol caused significant SC and keratinocyte perturbation in vitro together with damage to skin condition and function in vivo whereas ethanol did not. As a result, we show that ethanol-based sanitizers are better tolerated by skin, particularly in high-use settings, than other alcohols and should be the active ingredient of choice

The Presence of Essential and Non-Essential Stratum Corneum Proteases: The Vital Need for Protease Inhibitors

Dry skin is one of the most important concerns of consumers worldwide. Despite huge efforts over several decades, the personal care industry still does not offer complete solutions that satisfy the unmet needs of consumers for moisturizing treatments. The paucity of data for the underlying biochemical problems in and the effects of moisturizers on facial skin biology and physiology may partly explain this. Our recent color mapping studies based on bio-instrumental evaluations of skin capacitance and transepidermal water loss have revealed the complexity of facial skin. However, the biomolecular reasons for these subtle differences in the different zones of the face are unknown so far. As the maturation of the stratum corneum is vital for skin moisturization and optimal barrier function, we believe that the protease / proteaseinhibitor balance particularly of the plasminogen system may be key in these processes. Thus, our aim was to develop a specific dual plasmin and urokinase inhibitor for topical application to barrier-impaired skin and demonstrate its efficac

MSDmotif: exploring protein sites and motifs

<p>Abstract</p> <p>Background</p> <p>Protein structures have conserved features – motifs, which have a sufficient influence on the protein function. These motifs can be found in sequence as well as in 3D space. Understanding of these fragments is essential for 3D structure prediction, modelling and drug-design. The Protein Data Bank (PDB) is the source of this information however present search tools have limited 3D options to integrate protein sequence with its 3D structure.</p> <p>Results</p> <p>We describe here a web application for querying the PDB for ligands, binding sites, small 3D structural and sequence motifs and the underlying database. Novel algorithms for chemical fragments, 3D motifs, ϕ/ψ sequences, super-secondary structure motifs and for small 3D structural motif associations searches are incorporated. The interface provides functionality for visualization, search criteria creation, sequence and 3D multiple alignment options. MSDmotif is an integrated system where a results page is also a search form. A set of motif statistics is available for analysis. This set includes molecule and motif binding statistics, distribution of motif sequences, occurrence of an amino-acid within a motif, correlation of amino-acids side-chain charges within a motif and Ramachandran plots for each residue. The binding statistics are presented in association with properties that include a ligand fragment library. Access is also provided through the distributed Annotation System (DAS) protocol. An additional entry point facilitates XML requests with XML responses.</p> <p>Conclusion</p> <p>MSDmotif is unique by combining chemical, sequence and 3D data in a single search engine with a range of search and visualisation options. It provides multiple views of data found in the PDB archive for exploring protein structures.</p