Trichoscopy - a valuable tool for identifying conditions mimicking androgenetic alopecia.

Androgenetic alopecia (AGA) is the most prevalent type of hair loss in women and men. Recently, a European consensus group published guidelines for the diagnostic evaluation of AGA in men, women, and adolescents. This S1 guideline presents expert opinion-based recommendations for gender-dependent steps in the diagnostic procedure, which can easily be implemented in the daily clinical routine. For diagnosing AGA, detailed anamnesis and objective learning are not enough because there are several conditions mimicking this disease. Trichoscopy can be considered an important, non-invasive tool for diagnosing hair and scalp disorders that may have similar clinical signs to AGA.

Pressure modulates the self-cleavage step of the hairpin ribozyme.

The ability of certain RNAs, denoted as ribozymes, to not only store genetic information but also catalyse chemical reactions gave support to the RNA world hypothesis as a putative step in the development of early life on Earth. This, however, might have evolved under extreme environmental conditions, including the deep sea with pressures in the kbar regime. Here we study pressure-induced effects on the self-cleavage of hairpin ribozyme by following structural changes in real-time. Our results suggest that compression of the ribozyme leads to an accelerated transesterification reaction, being the self-cleavage step, although the overall process is retarded in the high-pressure regime. The results reveal that favourable interactions between the reaction site and neighbouring nucleobases are strengthened under pressure, resulting therefore in an accelerated self-cleavage step upon compression. These results suggest that properly engineered ribozymes may also act as piezophilic biocatalysts in addition to their hitherto known properties.

Exploring the effects of temperature and pressure on the structure and stability of a small RNA hairpin.

RNAs perform multiple vital roles within cells, including catalyzing biological reactions and expression of proteins. Small RNA hairpins (sRNAh) are the smallest functional entities of nucleic acids and are involved in various important biological functions such as ligand binding and tertiary folding initiation of proteins. We investigated the conformational and free energy landscape of the sRNAh gcUUCGgc over a wide range of temperatures and pressures using fluorescence resonance energy transfer, Fourier-transform infrared and UV/Vis spectroscopy as well as small-angle X-ray scattering on the unlabeled and/or fluorescently labeled sRNAh. The sRNAh shows a broad melting profile with continuous increase of unpaired conformations up to about 60°C. However, the sRNAh structure might not be fully unfolded at temperatures as high as 90°C and still comprise various partially unfolded compact conformations. Pressure up to 400MPa has a small effect on the base pairing and base stacking interactions of the sRNAh, indicating small conformational perturbations, only, which might originate from minor changes in packing and hydration of the RNA molecule upon compression. Pressurization at 70°C, i.e. at a temperature above the melting transition, has no significant effect on the conformational ensemble of the sRNAh, i.e., it does not promote formation of new native stem connections after thermal denaturation. Finally, we noticed that Cy3/Cy5 labeling of the sRNAh changes, probably via stacking interactions between the fluorescent dyes and the nucleotide rings, the stability of the sRNAh, thereby rendering FRET analysis of the conformational dynamics of such small RNA structure inappropriate.

Effect of cytochrome c on the phase behavior of charged multicomponent lipid membranes.

We studied the effect of submicromolar concentrations of cytochrome c (cyt c) on the phase behavior of ternary lipid membranes composed of charged dioleoylphosphatidylglycerol, egg sphingomyelin and cholesterol. The protein was found to induce micron-sized domains in membranes belonging to the single-fluid-phase region of the protein-free ternary mixture and, as a result, to expand the region of coexistence of liquid ordered (Lo) and liquid disordered (Ld) phases. Direct observations on individual vesicles revealed that protein adsorption increases the area of Ld domains. Measurements using a fluorescent analog of cyt c showed that the protein preferentially adsorbs onto domains belonging to the Ld phase. The adsorption was quantitatively characterized in terms of partitioning ratios between the Ld and the Lo phases. The protein was also found to induce vesicle leakage even at relatively low concentrations. In eukaryotic cells under normal physiological conditions, cyt c is localized within the intermembrane space of mitochondria. During cell apoptotis, cyt c is released into the cytosol and its adsorption to intracellular membranes may strongly perturb the lipid distribution within these membranes as suggested by our results.