Ecological Approach in the Substantiation of the Contexts of Distance Education Environment

The development of a human being takes place in the interaction with his/her life environment. Educational environment, including distance education environment, is particularly important for the facilitation of the sustainability of all society and the development of each individual. Ecological paradigm becomes more and more topical in modern education. The authors of the article base their research on the ecological approach, where an educational institution as the distance education environment is a multicomponent/multicontextual system. The results of theoretical research enabled the authors to identify several contexts of distance education environment: informative environment, technological environment and e-environment that complementary supplement each other. There have been analyzed and compared several concepts related to distance education, identifying in them the common and different features. Ecological approach enabled to reveal the essence of distance education and to describe distance education environment from different aspects

Tuning a Polar Molecule for Selective Cytoplasmic Delivery by a pH (Low) Insertion Peptide

Drug molecules are typically hydrophobic and small in order to traverse membranes to reach cytoplasmic targets, but we have discovered that more polar molecules can be delivered across membranes using water-soluble, moderately hydrophobic membrane peptides of the pHLIP (pH low insertion peptide) family. Delivery of polar cargo molecules could expand the chemical landscape for pharmacological agents that have useful activity but are too polar by normal drug criteria. The spontaneous insertion and folding of the pHLIP peptide across a lipid bilayer seeks a free energy minimum, and insertion is accompanied by a release of energy that can be used to translocate cell-impermeable cargo molecules. In this study, we report our first attempt to tune the hydrophobicity of a polar cargo, phallacidin, in a systematic manner. We present the design, synthesis, and characterization of three phallacidin cargoes, where the hydrophobicity of the cargo was tuned by the attachment of diamines of various lengths of hydrophobic chains. The phallacidin cargoes were conjugated to pHLIP and shown to selectively inhibit the proliferation of cancer cells in a concentration-dependent manner at low pH

Comparative Study of Tumor Targeting and Biodistribution of pH (Low) Insertion Peptides (pHLIP® Peptides) Conjugated with Different Fluorescent Dyes

Purpose Acidification of extracellular space promotes tumor development, progression, and invasiveness. pH (low) insertion peptides (pHLIP® peptides) belong to the class of pH-sensitive membrane peptides, which target acidic tumors and deliver imaging and/or therapeutic agents to cancer cells within tumors. Procedures Ex vivo fluorescent imaging of tissue and organs collected at various time points after administration of different pHLIP® variants conjugated with fluorescent dyes of various polarity was performed. Methods of multivariate statistical analyses were employed to establish classification between fluorescently labeled pHLIP® variants in multidimensional space of spectral parameters. Results The fluorescently labeled pHLIP® variants were classified based on their biodistribution profile and ability of targeting of primary tumors. Also, submillimeter-sized metastatic lesions in lungs were identified by ex vivo imaging after intravenous administration of fluorescent pHLIP® peptide. Conclusions Different cargo molecules conjugated with pHLIP® peptides can alter biodistribution and tumor targeting. The obtained knowledge is essential for the design of novel pHLIP®-based diagnostic and therapeutic agents targeting primary tumors and metastatic lesions

Diimide formation on the Ni(100) surface

Diimide (N2H2), an extremely reactive species, is observed as a gas phase product from the Ni(100) surface in the 200 to 450 K range during hydrazine thermal decomposition and during thermal desorption of predissociated ammonia. These results suggest that the primary mechanism for diimide formation is recombination of an adsorbed NH surface intermediate. The observation that diimide can be formed from predissociated ammonia illustrates that a nitrogen-nitrogen bond in the precursor is not required for diimide formation. Diimide formation from predissociated ammonia is enhanced by coadsorbed hydrogen, which we believe stabilizes NH on the Ni(100) surface. In addition, the direct decomposition of adsorbed N2H4 contributes to the production of diimide at 230 K.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30742/1/0000392.pd