Re-expression of glucuronyl C5-epimerase in the mutant MEF cells increases heparan sulfate epimerization but has no influence on the Golgi localization and enzymatic activity of 2-O-sulfotransferase.

Heparan sulfate (HS) is a linear and complex polysaccharide that modulates the biological activities through protein recognition and interaction. Evidence indicates that protein-binding properties of HS are largely dependent on distinctive sulfation and epimerization patterns that are modified by a series of Golgi-localized enzymes. In particular, the glucuronyl C5-epimerase (Hsepi) converts D-glucuronic acid (GlcA) residues to L-iduronic acid (IdoA) and 2-O-sulfotransferase (2OST) catalyzes sulfation at C2 position of IdoA and rarely GlcA residues. Mice lacking both Hsepi and 2OST display multiple development defects, indicating the importance of IdoA in HS. Here, to gain greater insights of HS structure-function relationships, as well as a better understanding of the regulatory mechanisms of Hsepi and 2OST, the fine structure and cellular signaling functions of HS were investigated after restoration of Hsepi in the mutant mouse embryonic fibroblast (MEF) cells. Introduction of Hsepi into the Hsepi mutant MEF cells led to robustly increased proportion of IdoA residues, which rescued the cell signaling in response to fibroblast growth factor 2. However, we found that Hsepi knockout had no influence on either cellular transport or enzymatic activity of 2OST in the MEF cells, which is not in accord with the findings suggesting that the enzymatic activity and cellular transport of 2OST and Hsepi might be differently regulated.

A Purified Glucomannan Oligosaccharide from Amorphophallus konjac Improves Colonic Mucosal Barrier Function via Enhancing Butyrate Production and Histone Protein H3 and H4 Acetylation.

A structurally defined konjac glucomannan oligosaccharide (KGMOS) with a relatively high molecular weight and narrow molecular weight distribution (molecular weight ranging from 3000 to 4000 Da, degree of polymerization (dp) 8-11) was prepared from native konjac glucomannan (KGM), and the beneficial effects and molecular mechanisms of KGMOS on colonic functions were investigated in C57BL/6 mice. The results are the first to reveal that KGMOS regulated intestinal microflora composition to facilitate the production of colonic butyrate. Elevated butyrate production further increased the acetylation of histone proteins H3 and H4 and thus enhanced the transcription of the major colonic mucin gene Muc2 and the secretion of mucin elements, which represents a new molecular mechanism of KGM oligosaccharide consumption. The findings indicate that KGM oligosaccharides with specific molecular sizes have highly desirable functional properties and potentially could improve gut health by promoting the barrier function of the colonic mucosa.

Effect of Mach number on droplet aerobreakup in shear stripping regime.

ABSTRACT: The present experimental study investigates the shear stripping breakup of single droplets in subsonic and supersonic gaseous flows. In contrast to most research that places emphasis on the Weber number (We), we focus on the individual effects exerted by flow Mach (M ∞) and Reynolds numbers (Re). Millimeter-sized droplets made of either ethylene glycol or water are exposed to shock-induced flows. Shadowgraph and schlieren images of the breakup process are recorded by an ultra-high-speed camera. The experimental We is constrained at 1100, while M ∞ is varied from 0.3 to 1.19 and Re from 2600 to 24,000. A systematic analysis of the experiment series reveals that the breakup pattern alters with M ∞ although a constant We is maintained. The classical stripping behavior with fine mist shed from the peripheral sheet changes to rupture of multiple bags along the periphery at M ∞ = 0.63, and further to stretching of ligament structures from the leeward surface at M ∞ = 1.19. The corresponding breakup initiation is delayed and the resultant fragments are sized less uniformly and distributed over a narrower spread. In terms of the early-stage deformation, droplets experience less intense flattening and slower sheet growth at higher M ∞. The change of Re introduces additional variations, but only to a minor extent.

[Study on chemical constituents from Mastic (Pistacia lentiscus)].

Phytochemical investigation on the methanolic extract of Mastic by using various chromatographic techniques led to the isolation of 9 compounds. Based on the analysis of spectroscopic data(NMR and MS) and/or comparisons with the data reported in the literature, their structures were elucidated as 3ß,8α,13-trihydroxypolypoda-14-methoxy-14-methyl-17,21-diene(1), 4-hydroxymyrtenal(2),3-methyl-6-(prop-1-en-2-yl)cyclohex-3-ene-1, 2-diol(3), 2-oxo-Δ~3-4,5,5-trimethylcyclopentynyl acidic acid(4),(1S,2R,3R,5R)-6,6-dimethyl-4-methylidenebicyclo[3.1.1]-heptane-2,3-diol(5),(4R)-1-methyl-4-(1-hydroxyisopropyl)cyclohexene-6-one(6), 6,6-dimethyl-4-hydroxy[3.1.1]hept-2-ene-2-carboxylic acid(7), 6,6-dimethyl[3.1.1]hept-2-ene-2-carboxylic acid(8), 6,6-dimethyl-4-oxobicyclo[3.1.1]hept-2-ene-2-carboxylic acid(9). Compound 1 is a new compound and 2-9 were isolated from this species for the first time. In vitro cytotoxicity assay results indicated that compounds 1, 6 and 7 showed significant inhibitory effects against human lung cancer cell line A549 with IC_(50) values of 20.4, 25.1 and 22.5 µmoL·L~(-1).