Imaging Glycosylation In Vivo by Metabolic Labeling and Magnetic Resonance Imaging

Glycosylation is a ubiquitous post‐translational modification, present in over 50 % of the proteins in the human genome, 1 with important roles in cell–cell communication and migration. Interest in glycome profiling has increased with the realization that glycans can be used as biomarkers of many diseases, 2 including cancer. 3 We report here the first tomographic imaging of glycosylated tissues in live mice by using metabolic labeling and a gadolinium‐based bioorthogonal MRI probe. Significant N‐azidoacetylgalactosamine dependent T₁ contrast was observed in vivo two hours after probe administration. Tumor, kidney, and liver showed significant contrast, and several other tissues, including the pancreas, spleen, heart, and intestines, showed a very high contrast (>10‐fold). This approach has the potential to enable the rapid and non‐invasive magnetic resonance imaging of glycosylated tissues in vivo in preclinical models of disease.     

Disordering of phospholipid headgroups induced by a small amount of polyethylene oxide

We present a ³¹P NMR spectroscopy study of planar glass‐plate‐oriented multi‐bilayers of dimyristoylphosphatidylcholine (DMPC) with addition of polyethylene oxide (PEO). This work revealed the presence of a new component in the spectra that appeared only with addition of a small fraction of PEO (up to one PEO segment per dimyristoylphosphatidylcholine molecule) and disappeared when larger amounts of PEO were added. We explained this phenomenon as an effect of an inhomogeneous force field induced by the PEO molecules located at a certain depth in the lipid membrane interface region. Copyright © 2012 John Wiley & Sons, Ltd.     

Mobility of molecules and diagram of the state of a glyceryl monooleate-water system according to NMR data

Transverse relaxation and self-diffusion of molecules in a glyceryl monooleate (monoolein)-D₂O system was studied using pulsed ¹H NMR in a range of water concentrations from 10 to 30 wt % and a range of temperatures from 20 to 90°C. It was noted that self-diffusion is described by one or two self-diffusion coefficients, depending on the temperature and concentration of water, while NMR-relaxation has a complex form. It was determined that with a reduction in the transverse magnetization, a component that has a form similar to Gaussian and relaxation times of 70 to 250 μs is observed at certain temperatures and concentrations of water, confirming the formation of structures in which glyceryl monooleate molecules (GM) are characterized by anisotropic rotational mobility. It was demonstrated that the ranges of the concentrations of water and temperature in which this component is observed correspond to liquid-crystalline phase for lamellar and inverse hexagonal structural organizations of lipids, according to the state diagram obtained by X-ray diffraction. In the state diagram areas corresponding to micellar and cubic structures (characterized by the isotropic rotation of GM molecules in the time scale of NMR), multiexponential decays of magnetization with average relaxation times were noted in the range of 10 to 200 ms. A number of features were discovered with the use of NMR: specimens always contain structures with isotropic rotational mobility in the presence of structures characterized by anisotropic rotational mobility; a change in the fraction of the structures with anisotropic rotational mobility takes place slowly over 5–15 K, not abruptly. Our conclusions regarding the polymorphism of a GM-D₂O system in the presence of anisotropic structures was confirmed by an analysis of the transverse NMR relaxation in an egg phosphatidylcholine-D₂O system, for which the presence of only lamellar liquid-crystalline structure is confirmed by ³¹P NMR.     

Synthesis and fungicidal activity of methylsulfanylmethyl ether derivatives of levoglucosenone

Chemistry of Heterocyclic Compounds - A series of derivatives were synthesized on the basis of levoglucosenone that contained hydroxy groups at the С-4 atom or С-2 and С-4 atoms...     

Durability of Thermoviscoelastic Bodies Under Long-Term Cyclic Loading

International Applied Mechanics - An energy failure criterion for thermoviscoelastic structural members subject to abrasive wear and dissipative heating is proposed. The criterion is used to...     

Mechanochemical Preparations of Anion Coordinated Architectures Based on 3-Iodoethynylpyridine and 3-Iodoethynylbenzoic Acid

The halogen bond has previously been explored as a versatile tool in crystal engineering and anion coordination chemistry, with mechanochemical synthetic techniques having been shown to provide convenient routes towards cocrystals. In an effort to expand our knowledge on the role of halogen bonding in anion coordination, here we explore a series of cocrystals formed between 3-iodoethynylpyridine and 3-iodoethynylbenzoic acid with halide salts. In total, we report the single-crystal X-ray structures of six new cocrystals prepared by mechanochemical ball milling, with all structures exhibiting C≡C−I⋅⋅⋅X⁻ (X=Cl, Br) halogen bonds. Whereas cocrystals featuring a pyridine group favoured the formation of discrete entities, cocrystals featuring a benzoic acid group yielded an alternation of halogen and hydrogen bonds. The compounds studied herein were further characterized by ¹³C and ³¹P solid-state nuclear magnetic resonance, with the chemical shifts offering a clear and convenient method of identifying the occurrence of halogen bonding, using the crude product obtained directly from the mechanochemical ball milling. Whereas the ³¹P chemical shifts were quickly able to identify the occurrence of cocrystallization, ¹³C solid-state NMR was diagnostic of both the occurrence of halogen bonding and of hydrogen bonding.