Determination of the Triple Helical Chain Conformation of β‑Glucan by Facile and Reliable Triple-Detector Size Exclusion Chromatography

Triple helical polysaccharides (t-polysaccharides) are easily gelated in water, resulting in difficult fractionation, leading to the complex and time-consuming chain conformational characterization. Moreover, the fractionation is not always successful due to the coexistence of individual chains and aggregates. In this work, we developed a facile and reliable method to rapidly and accurately characterize the chain conformation of t-polysaccharide without fractionation needed in traditional conformation characterization. A triple helical β-1,3-glucan (t-β-1,3-glucan), extracted from the fruiting bodies of Lentinus edodes, was identified to consist of a β-1,3-glucan with two β-1,6-d-glucopyranoside branchings for every five β-1,3-glucopyranoside linear linkages by one- and two-dimensional NMR and GC-MS analysis. The chain conformations of the t-β-glucan in aqueous solution and in DMSO were successfully characterized by a combination of size exclusion chromatography (SEC), multiangle static light scattering, a differential refractometer, and a capillary viscosity detector (triple-detector SEC). The results revealed that the predominate species of the t-β-glucan in a 0.15 M NaCl aqueous solution existed as a triple helical conformation with high chain stiffness, and a few aggregates (4%) coexisted here. The Mark–Houwink and ⟨<i>S</i>²⟩^1/2 versus <i>M</i>_w equations of individual triple helical chains and aggregates were obtained simultaneously, and the results confirmed again the coexistence of two kinds of chain conformations. The fractal dimension indicated that the aggregate in the aqueous solution was a kind of reversible microgel with a 3D network structure. Furthermore, the chain morphology of the t-β-glucan in aqueous solution was observed directly by transmission electron microscopy and atomic force microscopy to support the worm-like chain for the individuals and 3D network for the aggregates. The triple-detector SEC technology was facile and reliable for the system with two fractions of different chain conformation, and the test time required was only 1/30 of what the traditional method needed

Significant Reduction in Fine Particulate Matter in Beijing during 2022 Beijing Winter Olympics

To investigate the air quality improvement during 2022 Beijing Winter Olympic Games (WOG), continuous hourly observations of fine particulate matter (PM2.5) and chemical fractions were performed in Beijing from January to March 2017–2022. Benefiting from the aggressive mitigation measures, significant reductions in the PM2.5 concentrations and chemical species in Beijing were observed during WOG. During strict control period, six sources of PM2.5 in Beijing were identified with positive matrix factorization model including secondary source (SS), industrial emissions (IEs), vehicle emissions (VEs), coal combustion (CC), fireworks burning (FB), and dust. Additionally, an obvious decline was observed in the sources of PM2.5, and no contribution of FB was quantitatively identified in 2022. Based on the multiple linear regression analysis, it found that meteorological parameters accounted for 46.1% of the total variation in the PM2.5 concentration, while source control measures accounted for 53.9% of the total variation, indicating that aggressive mitigation measures played a more important role in the decline in the PM2.5 concentration than meteorological conditions. This study could provide valuable insight into achieving air quality improvement and formulating policies in developing countries plagued by heavy air pollution

Yeast β‑Glucan Suppresses the Chronic Inflammation and Improves the Microenvironment in Adipose Tissues of ob/ob Mice

Inflammation in visceral adipose tissues (VATs) contributes to the pathology of diabetes. This study focused on the inflammatory regulation in VATs by a yeast β-1,3-glucan (BYG) orally administered to ob/ob mice. BYG decreased pro-inflammatory modulators of TNF-α, IL-6, IL-1β, CCL2, and <i>SAA3</i>, and increased anti-inflammatory factors of <i>Azgp1</i> (2.53 ± 0.02-fold change) at protein and/or mRNA levels (<i>p</i> < 0.05). Remarkably, BYG decreased the degree of adipose tissue macrophages (ATMs) infiltration to 82.5 ± 8.3%, especially the newly recruited ATMs. Interestingly, BYG increased the protective Th2 cell regulator <i>GATA3</i> (7.72 ± 0.04-fold change) and decreased immunosuppressors <i>IL-10</i> and IL-1ra, suggesting that BYG elicited inflammation inhibition via stimulating immune responses. Additionally, BYG increased the gut microbiota proportion of <i>Akkermansia</i> from 0.07% to 4.85% and improved the microenvironment of VATs through decreasing fibrosis and angiogenesis. These findings suggest that BYG has anti-inflammatory effect in diabetic mice, which can be used as a food component and/or therapeutic agent for diabetes

Comparison of the bone morphology parameters of lumbar vertebrae in the four groups.

<p>^▲<i>p</i> <0.01 vs. sham group; ^☆<i>p</i> <0.01 vs. model group. BV, bone volume; TV, total tissue volume; BV/TV, bone volume to total tissue volume ratio (bone volume fraction); SMI, structure model index; Tb.N, trabecular number; Tb.Th, trabecular thickness; Tb.Sp, trabecular spacing; BS/BV, bone surface to bone volume ratio.</p

Assessment of the Impact of Zoledronic Acid on Ovariectomized Osteoporosis Model Using Micro-CT Scanning

<div><p>Purpose/Objective</p><p>Prompted by preliminary findings, this study was conducted to investigate the impact of zoledronic acid on the cancellous bone microstructure and its effect on the level of β-catenin in a mouse model of postmenopausal osteoporosis.</p><p>Methods and Materials</p><p>96 8-week-old specific-pathogen-free C57BL/6 mice were randomly divided into 4 groups (24 per group): a sham group, an ovariectomized osteoporosis model group, an estradiol-treated group, and a zoledronic acid-treated group. Five months after surgery, the third lumbar vertebra and left femur of the animals were dissected and scanned using micro-computed tomography (micro-CT) to acquire three-dimensional imagery of their cancellous bone microstructure. The impact of ovariectomy, the effect of estradiol, and the effect of zoledronic acid intervention on cancellous bone microstructure, as well as on the expression of β-catenin, were evaluated.</p><p>Results</p><p>The estradiol-treated and the zoledronic acid-treated group exhibited a significant increase in the bone volume fraction, trabecular number, trabecular thickness, bone surface to bone volume ratio (BS/BV), and β-catenin expression, when compared with those of the control group (<i>P</i> <0.01). In contrast, the structure model index, trabecular separation, and BS/BV were significantly lower compared with those of the model group (<i>P</i> <0.01). No differences were observed in the above parameters between animals of the zoledronic acid-treated and the estradiol-treated group.</p><p>Conclusion</p><p>These results suggest that increased β-catenin expression may be the mechanism underlying zoledronic acid-related improvement in the cancellous bone microstructure in ovariectomized mice. Our findings provide a scientific rationale for using zoledronic acid as a therapeutic intervention to prevent bone loss in post-menopausal women.</p></div

Expression of β-catenin in each group (IHC, ×400).

<p>(1a-1d) Representatives of β-catenin staining in bone tissue cells in sham/normal group (1a), ovariectomized osteoporosis associated with estradiol-treated group (1b), ovariectomized osteoporosis associated with zoledronic acid-treated group (1c), and ovariectomized osteoporosis model group (1d). All photomicrographs images at 400x magnification.</p

Micro-CT of lumbar vertebrae in the four groups.

<p>(3a-3d) Three-dimensional images reconstructed from micro-CT analysis on the cortical and trabecular bone microarchitecture of 3rd lumbar (cross section) in four groups.</p

Intermolecular Interaction and the Extended Wormlike Chain Conformation of Chitin in NaOH/Urea Aqueous Solution

The intra- and intermolecular interactions of chitin in NaOH/urea aqueous system were studied by a combination of NMR measurements (including ¹³C NMR, ²³Na NMR, and ¹⁵N NMR) and differential scanning calorimetry. The results revealed that the NaOH and chitin formed a hydrogen-bonded complex that was surrounded by the urea hydrates to form a sheath-like structure, leading to the good dissolution. The optimal concentration range, in which chitin was molecularly dispersed in NaOH/urea aqueous, was found to investigate the chain conformation in the dilute solution with a combination of static and dynamic light scattering. The weight-average molecular weight (<i>M</i>_w), radii of gyration (⟨<i>R</i>_g⟩_<i>z</i>), and hydrodynamic radii (⟨<i>R</i>_h⟩_<i>z</i>) values of chitin were determined, and the structure-sensitive parameter (ρ) and persistent length (<i>L</i>_p) were calculated to be >2.0 and ∼30 nm, respectively, suggesting an extended wormlike chain conformation. The visualized images from TEM, cryo-TEM, and AFM indicated that, chitin nanofibers were fabricated from the parallel aggregation of chitin chains in NaOH/urea system. This work would provide a theoretical guidance for constructing novel chitin-based nanomaterials via “bottom-up” method at the molecular level