Dextran hydrogels by crosslinking with amino acid diamines and their viscoelastic properties

Amine functionalized polysaccharide hydrogels such as those based on chitosan are widely examined as biomaterials. Here we set out to develop a facile procedure for developing such hydrogels by crosslinking dextran with amino acid diamines. The dextran-amino acid gels were formed by the addition of the amino acid diamines to a dextran and epicholorohydrin solution once it became homogeneous. This was demonstrated with three amino acid diamines, lysine, lysine methyl ester, and cystine dimethyl ester. Hydrogel networks with albumin entrapped were also demonstrated. These hydrogels were characterized by FTIR, SEM, rotational rheometry, swelling studies and cell biocompatibility analysis. These hydrogels showed the unexpected pH-responsive behavior of greater swelling at more basic pH, similar to that of an anionic hydrogel. This is uncharacteristic for amine functionalized gels as they typically exhibit cationic hydrogel behavior. All hydrogels showed similar biocompatibility to that of dextran crosslinked without amino acids

Dextran hydrogels by crosslinking with amino acid diamines and their viscoelastic properties

Amine functionalized polysaccharide hydrogels such as those based on chitosan are widely examined as biomaterials. Here we set out to develop a facile procedure for developing such hydrogels by crosslinking dextran with amino acid diamines. The dextran-amino acid gels were formed by the addition of the amino acid diamines to a dextran and epichlorohydrin solution once it became homogeneous. This was demonstrated with three amino acid diamines, lysine, lysine methyl ester, and cystine dimethyl ester. Hydrogel networks with albumin entrapped were also demonstrated. These hydrogels were characterized by FTIR, SEM, rotational rheometry, swelling studies and cell biocompatibility analysis. These hydrogels showed the unexpected pH-responsive behavior of greater swelling at more basic pH, similar to that of an anionic hydrogel. This is uncharacteristic for amine functionalized gels as they typically exhibit cationic hydrogel behavior. All hydrogels showed similar biocompatibility to that of dextran crosslinked without amino acids

Chemotaxonomy of \u3ci\u3eTheobroma\u3c/i\u3e and \u3ci\u3eHerrania\u3c/i\u3e (Malvaceae) and \u3ci\u3eIlex \u3c/i\u3e(Aquifoliaceae) species

Biosynthesis of purine alkaloids has arisen by convergent evolution in several plant families across the angiosperm phylogeny. Global secondary metabolite variation in these derived taxa is not well understood within the context of their congeners and related lineages. Wild crop relatives represent the evolutionary background of edible and medicinal plants, enabling an understanding of the origins of species by correlating diversification with concomitant phenotypic changes prior to human-mediated selection and domestication. Chemotaxonomy, as part of an integrative taxonomy uniting botany, phytochemistry, and systematics, is an analytical methodology for identifying significant changes in metabolite composition across taxa in order to understand species chemodiversity within a phylogenetic context. In the current work, the chemotaxonomy of caffeine-containing plants is developed via liquid chromatography-mass spectrometry-based (LC-MS) metabolomics of Ilex L. (Aquifoliaceae) and Theobroma L. and Herrania Goudot (Byttneriodeae, Malvaceae) species. Caffeine-containing species were identified and targeted for comparative phytochemical analyses with their wild relatives, assessing purine alkaloid variability, identifying unique secondary metabolite markers, and testing metabolome-lineage relationships as part of chemotaxonomic species delimitation and phytochemical lineage reconstruction. Metabolomes of caffeine-containing taxa were profiled to differentiate species, taxonomic sections, and genera using multivariate statistics and chemometrics methodologies, including principal component analysis (PCA), non-metric multidimensional scaling (NMDS), hierarchical clustering analysis (HCA), discriminant analysis (OPLS-DA), and S-plot modeling. Significant qualitative and quantitative metabolite markers were identified and profiled across species. Parallel upregulation of purine alkaloids and other secondary metabolites are suggested for clades within Ilex and for Theobroma and Herrania species. Evidence from LC-MS metabolomics-based chemotaxonomy of caffeine-containing species and their wild relatives demonstrate how secondary metabolite chemistry and global metabolome divergence track taxonomic relationships, providing new insights via synthesis within a phylogenetic framework

“The Best Time is Now!”: The Temporal and Spatial Dynamics of Women Opting in to Self-Employment

This paper explores the potential for the concepts of time and space, together with the analogy of landscapes, to aid the exploration and understandings of women's careers. Drawing upon case studies of women who chose to opt in to self-employment, we examine how the multi-faceted histories of these women are drawn upon as they remember the past, explain contemporary experiences, and anticipate their futures. All the women spoke of opting in to self-employment as the best of times; they talked of greater control over work content, the relationship between family, gender and paid work, and self-determinism and autonomy. They noted times when their careers were frayed but only in retrospect could they assess the context, consequences and impact of events. The framework of careerscapes — our unique blending of the notion of careers along with socio-economic and geographical interpretations of scapes — offers a framework to examine frayed careers and multiple aspects of working and caring over time and space

A PET Imaging Strategy to Visualize Activated T Cells in Acute Graft-versus-Host Disease Elicited by Allogenic Hematopoietic Cell Transplant

A major barrier to successful use of allogeneic hematopoietic cell transplantation is acute graft-versus-host disease (aGVHD), a devastating condition that arises when donor T cells attack host tissues. With current technologies, aGVHD diagnosis is typically made after end-organ injury and often requires invasive tests and tissue biopsies. This affects patient prognosis as treatments are dramatically less effective at late disease stages. Here, we show that a novel PET radiotracer, 2'-deoxy-2'-[18F]fluoro-9-β-D-arabinofuranosylguanine ([18F]F-AraG), targeted toward two salvage kinase pathways preferentially accumulates in activated primary T cells. [18F]F-AraG PET imaging of a murine aGVHD model enabled visualization of secondary lymphoid organs harboring activated donor T cells prior to clinical symptoms. Tracer biodistribution in healthy humans showed favorable kinetics. This new PET strategy has great potential for early aGVHD diagnosis, enabling timely treatments and improved patient outcomes. [18F]F-AraG may be useful for imaging activated T cells in various biomedical applications. Cancer Res; 77(11); 2893-902. ©2017 AACR