This report provides a perspective on metabolic glycoengineering methodology developed over the past two decades that allows natural sialic acids to be replaced with chemical variants in living cells and animals. Examples are given demonstrating how this technology provides the glycoscientist with chemical tools that are beginning to reproduce Mother Nature's control over complex biological systems - such as the human brain - through subtle modifications in sialic acid chemistry. Several metabolic substrates (e.g., ManNAc, Neu5Ac, and CMP-Neu5Ac analogs) can be used to feed flux into the sialic acid biosynthetic pathway resulting in numerous - and sometime quite unexpected - biological repercussions upon nonnatural sialoside display in cellular glycans. Once on the cell surface, ketone-, azide-, thiol-, or alkyne-modified glycans can be transformed with numerous ligands via bioorthogonal chemoselective ligation reactions, greatly increasing the versatility and potential application of this technology. Recently, sialic acid glycoengineering methodology has been extended to other pathways with analog incorporation now possible in surface-displayed GalNAc and fucose residues as well as nucleocytoplasmic O-GlcNAc-modified proteins. Finally, recent efforts to increase the "druggability" of sugar analogs used in metabolic glycoengineering, which have resulted in unanticipated "scaffold-dependent" activities, are summarized.

Short-chain fatty acid (SCFA)-carbohydrate hybrid molecules that target both histone deacetylation and glycosylation pathways to achieve sugar-dependent activity against cancer cells are described in this article. Specifically, n-butyrate esters of N-acetyl-D-mannosamine (But4ManNAc, 1) induced apoptosis, whereas corresponding N-acetyl-D-glucosamine (But4GlcNAc, 2), D-mannose (But5Man, 3), or glycerol (tributryin, 4) derivatives only provided transient cell cycle arrest. Western blots, reporter gene assays, and cell cycle analysis established that n-butyrate, when delivered to cells via any carbohydrate scaffold, functioned as a histone deacetylase inhibitor (HDACi), upregulated p21WAF1/Cip1 expression, and inhibited proliferation. However, only 1, a compound that primed sialic acid biosynthesis and modulated the expression of a different set of genes compared to 3, ultimately killed the cells. These results demonstrate that the biological activity of butyrate can be tuned by sugars to improve its anticancer properties.

Mitochondrial damage and ROS production may contribute to loss of PLT viability during storage, whereas cold storage is known to preserve PLT function. Here we demonstrate that 4°C storage results in less oxidant stress and preserves mitochondrial function and potential compared to RT.

BACKGROUND Transitioning from whole blood (WB) to components developed from efforts to maximize donor yield. Components are advantageous for specific derangements, but treating hemorrhage with components requires significantly more volume to provide similar effects to WB. Because storage lesion and waste remain problematic, this study examined hemostatic function of refrigerated WB stored for 35 days in anticoagulants citrate–phosphate‐dextrose‐adenosine (CPDA‐1), citrate–phosphate‐dextrose (CPD), or citrate–phosphate‐double dextrose (CP2D). METHODS Refrigerated WB units from healthy donors were sampled over 35 days. Global hemostatic parameters were measured by thromboelastometry, thrombogram, platelet aggregometry, and platelet adhesion to collagen under shear conditions. The effects of transfusion filtration and mixing 35‐day stored product with fresh WB were evaluated. RESULTS Countable platelets declined as aggregation clusters appeared in microscopy. While gross platelet agonist‐induced aggregation declined over time, normalization revealed aggregation responses in remaining platelets. Peak thrombin generation increased over time. Clot strength diminished over storage in tissue factor–activated samples (normalized by filtration of aggregates). Functional fibrinogen responses remained consistent throughout. Filtration was necessary to maintain consistent platelet adhesion to collagen beyond collection day. Few differences were observed between anticoagulants, and stored/fresh mixing studies normalized coagulation parameters. CONCLUSIONS WB is easier to collect, store, and transfuse. WB provides platelets, an oft‐neglected, critical resuscitation component, but their individual numbers decline as aggregates appear, resulting in diminished coagulation response. WB has better performance in these assays when examined at earlier time points, but expirations designated to specific anticoagulants appear arbitrary for hemostatic functionality, as little changes beyond 21 days regardless of anticoagulant.

This study investigates the breadth of cellular responses engendered by short chain fatty acid (SCFA)-hexosamine hybrid molecules, a class of compounds long used in 'metabolic glycoengineering' that are now emerging as drug candidates. First, a 'mix-and-match' strategy showed that different SCFA (n-butyrate and acetate) appended to the same core sugar altered biological activity, complementing previous results [Campbell et al., (2008) J. Med. Chem. 51, 8135-8147] where a single type of SCFA elicited distinct responses. Microarray profiling then compared transcriptional responses engendered by regioisomerically-modified ManNAc, GlcNAc, and GalNAc analogs in MDA-MB-231 cells. These data -which were validated by qRT-PCR or Western analysis for ID1, TP53, HPSE, NQO1, EGR1 and VEGFA -showed a two-pronged response where a core set of genes was coordinately regulated by all analogs while each analog simultaneously uniquely regulated a larger number of genes. Finally, AutoDock modeling supported a mechanism where the analogs directly interact with elements of the NF-κB pathway. Together, these results establish the SCFA-hexosamine template as a versatile platform for modulating biological activity and developing new therapeutics.