Репозиторий Университета

© 2019 Elsevier B.V. Due to their unique optical properties upconversion nanoparticles (UCNPs) provide exceptionally high contrast for imaging of true nanoparticle distribution in excised human skin. It makes possible to show penetration of solid nanoparticles in skin treated with chemical enhancers. We demonstrated tracing upconversion nanoparticles in excised human skin by means of optical microscopy at the discrete particle level sensitivity to obtain their penetration profiles, which was validated by laser-ablation inductively-coupled-plasma mass-spectrometry. To demonstrate utilities of our method, UCNPs were coated with polymers, formulated in water and chemical enhancers, and applied on excised human skin mounted on Franz cells, followed by imaging using a custom-built laser-scanning microscope. To evaluate the toxicity impact on skin by polymer-coated UCNPs, we introduced a tissue engineering model of viable epidermis made of decellularized chick embryo skin seeded with keratinocytes. UCNPs formulated in water stopped in stratum corneum, whereas UCNPs formulated in ethanol-water solution crossed stratum corneum and reached viable epidermis – hence, the enhancement effect for solid nanoparticles was detected by optical microscopy. All polymer-coated UCNPs were found nontoxic within the accepted safety levels. The keratinocyte resilience to polyethyleneimine-coated UCNPs was surprising considering cytotoxicity of polyethyleneimine to two-dimensional cell cultures.

© 2018, Pleiades Publishing, Ltd. Mediator is a key factor in the regulation of expression of RNA polymerase II-transcribed genes. Recent studies have shown that Mediator acts as a coordinator of transcription activation and participates in maintaining chromatin architecture in the cell nucleus. In this review, we present current concepts on the structure and functions of Mediator.

© The Author(s) 2018. Published by Oxford University Press on behalf of the International Life Sciences Institute. All rights reserved. Vitamin B12 (B-12) deficiency is still relatively common in low-, medium-, and high-income countries, mainly because of dietary inadequacy and, to a lesser extent, malabsorption. This narrative review is based on a systematic search of evidence on methods to assess B-12 bioavailability and technologies to enhance its absorption. A total of 2523 scientific articles identified in PubMed and 1572 patents identified in Orbit Intelligence were prescreened. Among the reviewed methods, Schilling's test and/or its food-based version (using cobalamin-labeled egg yolk) were used for decades but have been discontinued, largely because they required radioactive cobalt. The qualitative CobaSorb test, based on changes in circulating holo-transcobalamin before and after B-12 administration, and the14C-labeled B-12 test for quantitative measurement of absorption of a low-dose radioactive tracer are currently the best available methods. Various forms of B-12 co-formulated with chemical enhancers (ie, salcaprozate sodium, 8-amino caprylate) or supplied via biotechnological methods (ie, microbiological techniques, plant cells expressing cobalamin binding proteins), encapsulation techniques (ie, emulsions, use of chitosan particles), and alternative routes of administration (ie, intranasal, transdermal administration) were identified as potential technologies to enhance B-12 absorption in humans. However, in most cases the evidence of absorption enhancement is limited.