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1.
Regulation and Function of Defense-Related Callose Deposition in Plants.
Wang, Y, Li, X, Fan, B, Zhu, C, Chen, Z
International journal of molecular sciences. 2021;(5)
Abstract
Plants are constantly exposed to a wide range of potential pathogens and to protect themselves, have developed a variety of chemical and physical defense mechanisms. Callose is a β-(1,3)-D-glucan that is widely distributed in higher plants. In addition to its role in normal growth and development, callose plays an important role in plant defense. Callose is deposited between the plasma membrane and the cell wall at the site of pathogen attack, at the plasmodesmata, and on other plant tissues to slow pathogen invasion and spread. Since it was first reported more than a century ago, defense-related callose deposition has been extensively studied in a wide-spectrum of plant-pathogen systems. Over the past 20 years or so, a large number of studies have been published that address the dynamic nature of pathogen-induced callose deposition, the complex regulation of synthesis and transport of defense-related callose and associated callose synthases, and its important roles in plant defense responses. In this review, we summarize our current understanding of the regulation and function of defense-related callose deposition in plants and discuss both the progresses and future challenges in addressing this complex defense mechanism as a critical component of a plant immune system.
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Comparing the diagnostic value of bronchoalveolar lavage fluid galactomannan, serum galactomannanan, and serum 1,3-β-d-glucan in non-neutropenic respiratory disease patients with invasive pulmonary aspergillosis.
Dai, Z, Cai, M, Yao, Y, Zhu, J, Lin, L, Fang, L, Li, Z, Yi, H, Chen, B, Liang, X
Medicine. 2021;(14):e25233
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Abstract
The incidence of invasive pulmonary aspergillosis (IPA) is increasing higher in non-neutropenic patients. This study aimed to assess the diagnostic performance of bronchoalveolar lavage fluid (BALF). Galactomannan (GM), serum GM, and 1,3-β-d-glucan (BDG) in non-neutropenic respiratory disease patients with IPA.A total of 333 non-neutropenic patients suspected IPA were recruited from Xiamen University Zhong Shan hospital between January 2016 and February 2019. One, 33, and 92 cases were diagnosed with proven, and possible IPA.BALF and serum GM were both elevated in the possible IPA group and the probable/proven IPA group (p < 0.001). BALF and serum GM showed a fair correlation in the possible IPA group (r = 0.286, p = 0.008), and moderate correlation in the probable/proven IPA group (r = 0.466, p = 0.005). When the cutoff value was 0.5, the sensitivity and negative likelihood ratio of BALF GM were superior to serum GM (78.3% vs 47.8%, 96.7% vs 91.6%). The specificity and positive likelihood ratio of BALF GM were slightly weaker than serum GM (91.8% vs 95.4%, 56.7% vs 85.0%). When the cutoff value was 1.0, the sensitivity and negative predictive value of BALF GM were better than serum GM (73.9% vs 26.1%, 94.5% vs 88.8%), and the specificity of were equivalent (99.2%). The optimal cutoff value of BALF GM was 0.6, wherein the sensitivity reached 78.3% and the specificity reached 95.4%. Given the extremely low sensitivity of serum BDG at different cutoff values (≥10 μg/mL = 5.3%, ≥20 μg/mL = 2.1%), it cannot be used as a preferred biomarker.The diagnostic performance of BALF GM was superior to other biomarkers and the optimal cutoff value was 0.6.
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Advances in Cell Wall Matrix Research with a Focus on Mixed-Linkage Glucan.
Kim, SJ, Brandizzi, F
Plant & cell physiology. 2021;(12):1839-1846
Abstract
Mixed β(1,3;1,4)-linkage glucan (MLG) is commonly found in the monocot lineage, at particularly high levels in the Poaceae family, but also in the evolutionally distant genus, Equisetum. MLG has several properties that make it unique from other plant cell wall polysaccharides. It consists of β1,4-linked polymers of glucose interspersed with β1,3-linkages, but the presence of β1,3-linkages provides quite different physical properties compared to its closest form of the cell wall component, cellulose. The mechanisms of MLG biosynthesis have been investigated to understand whether single or multiple enzymes are required to build mixed linkages in the glucan chain. Currently, MLG synthesis by a single enzyme is supported by mutagenesis analyses of cellulose synthase-like F6, the major MLG synthase, but further investigation is needed to gather mechanistic insights. Because of transient accumulation of MLG in elongating cells and vegetative tissues, several hypotheses have been proposed to explain the role of MLG in the plant cell wall. Studies have been carried out to identify gene expression regulators during development and light cycles as well as enzymes involved in MLG organization in the cell wall. A role of MLG as a storage molecule in grains is evident, but the role of MLG in vegetative tissues is still not well understood. Characterization of a cell wall component is difficult due to the complex heterogeneity of the plant cell wall. However, as detailed in this review, recent exciting research has made significant impacts in the understanding of MLG biology in plants.
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Resistant starch supplementation increases crypt cell proliferative state in the rectal mucosa of older healthy participants.
Malcomson, FC, Willis, ND, McCallum, I, Xie, L, Ouwehand, AC, Stowell, JD, Kelly, S, Bradburn, DM, Belshaw, NJ, Johnson, IT, et al
The British journal of nutrition. 2020;(4):374-385
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Abstract
There is strong evidence that foods containing dietary fibre protect against colorectal cancer, resulting at least in part from its anti-proliferative properties. This study aimed to investigate the effects of supplementation with two non-digestible carbohydrates, resistant starch (RS) and polydextrose (PD), on crypt cell proliferative state (CCPS) in the macroscopically normal rectal mucosa of healthy individuals. We also investigated relationships between expression of regulators of apoptosis and of the cell cycle on markers of CCPS. Seventy-five healthy participants were supplemented with RS and/or PD or placebo for 50 d in a 2 × 2 factorial design in a randomised, double-blind, placebo-controlled trial (the Dietary Intervention, Stem cells and Colorectal Cancer (DISC) Study). CCPS was assessed, and the expression of regulators of the cell cycle and of apoptosis was measured by quantitative PCR in rectal mucosal biopsies. SCFA concentrations were quantified in faecal samples collected pre- and post-intervention. Supplementation with RS increased the total number of mitotic cells within the crypt by 60 % (P = 0·001) compared with placebo. This effect was limited to older participants (aged ≥50 years). No other differences were observed for the treatments with PD or RS as compared with their respective controls. PD did not influence any of the measured variables. RS, however, increased cell proliferation in the crypts of the macroscopically-normal rectum of older adults. Our findings suggest that the effects of RS on CCPS are not only dose, type of RS and health status-specific but are also influenced by age.
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Glucanases and Chitinases.
Roncero, C, Vázquez de Aldana, CR
Current topics in microbiology and immunology. 2020;:131-166
Abstract
In many yeast and fungi, β-(1,3)-glucan and chitin are essential components of the cell wall, an important structure that surrounds cells and which is responsible for their mechanical protection and necessary for maintaining the cellular shape. In addition, the cell wall is a dynamic structure that needs to be remodelled along with the different phases of the fungal life cycle or in response to extracellular stimuli. Since β-(1,3)-glucan and chitin perform a central structural role in the assembly of the cell wall, it has been postulated that β-(1,3)-glucanases and chitinases should perform an important function in cell wall softening and remodelling. This review focusses on fungal glucanases and chitinases and their role during fungal morphogenesis.
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The Novel Effects of a Hydrolyzed Polysaccharide Dietary Supplement on Immune, Hepatic, and Renal Function in Adults with HIV in a Randomized, Double-Blind, Placebo-Control Trial.
Lewis, JE, Atlas Bsn, SE, Abbas, MH, Rasul, A, Farooqi, A, Lantigua, LA, Michaud, F, Goldberg, S, Lages, LC, Higuera, OL, et al
Journal of dietary supplements. 2020;(4):429-441
Abstract
The primary objective of the study was to evaluate the effects of a hydrolyzed polysaccharide, rice bran arabinoxylan compound (RBAC), on immune, hepatic, and renal function in HIV + individuals. A 6-month randomized double-blind placebo-controlled trial was utilized to conduct the intervention. Forty-seven HIV + individuals on stable antiretroviral therapy were enrolled and randomly assigned to one of the 2 study conditions (n = 22 RBAC and n = 25 placebo) and consumed 3 gram/day of either compound for 6 months. Participants were assessed at baseline and 3 and 6 months follow-up for CD4+ and CD8+, liver enzymes, and kidney function. No side effects were reported, and liver and kidney markers remained nearly completely within normal limits. The percentage change in CD4+ was similar for the placebo (+2.2%) and RBAC (+3.1%) groups at 6 months follow-up. The percentage change in CD8+ count significantly decreased from baseline to 6 months in the RBAC group (-5.2%), whereas it increased in the placebo group (+57.8%; p = 0.04). The CD4+/CD8+ ratio improved clinically in the RBAC group from 0.95 (SD = 0.62) at baseline to 1.07 (SD = 0.11) at 6 months, whereas it declined in the placebo group from 0.96 (SD = 0.80) at baseline to 0.72 (SD = 0.59) at 6 months. Our results showed a statistically significant decrease in CD8+ count and a clinically significant increase in CD4+/CD8+ ratio for the RBAC group compared to the placebo group. Thus, the results of this study suggest that the immunomodulatory and antisenescent activities of RBAC are promising for the HIV population.
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Effectiveness of Sterilized Symbiotic Drink Containing Lactobacillus helveticus Comparable to Probiotic Alone in Patients with Constipation-Predominant Irritable Bowel Syndrome.
Bahrudin, MF, Abdul Rani, R, Tamil, AM, Mokhtar, NM, Raja Ali, RA
Digestive diseases and sciences. 2020;(2):541-549
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Abstract
BACKGROUND This study aimed to objectively investigate whether the addition of polydextrose to sterilized probiotic containing Lactobacillus helveticus will confer benefits to constipation-predominant irritable bowel syndrome patients. METHODS A total of 163 patients were randomized into two groups: Group A to consume 350 mL of sterilized probiotic with 5.85 g polydextrose daily for 1 week and Group B without polydextrose. Intestinal transit time, fecal pH, fecal weight, and modified Garrigues questionnaires for pre- and post-consumption were assessed. RESULTS Median intestinal transit time was significantly reduced from 58 (IQR 43-72) to 45 (IQR 24-59) hours and 48 (IQR 31-72) to 30 (IQR 24-49) hours for Groups A and B, respectively (p < 0.01). Fecal pH for Groups A and B was significantly reduced from 6.57 ± 0.96 to 6.13 ± 0.95 (p = 0.003) and 6.58 ± 1.0 to 5.87 ± 0.83 (p < 0.001), respectively. Fecal weight for Group A was significantly increased from 8 g ± 6.4 g to 9.8 g ± 7.6 g (p = 0.003), but it was reduced for Group B from 13.3 g ± 19.4 g to 11.2 g ± 6.6 g (p = 0.308). Constipation-related symptoms were significantly improved for both groups. CONCLUSIONS The addition of polydextrose to sterilized probiotic containing L. helveticus did not show significant benefits to constipation-predominant irritable bowel syndrome patients. However, daily consumption of sterilized probiotic containing L. helveticus with or without polydextrose for a week alleviated constipation-related symptoms and objectively reduced both fecal pH and intestinal transit time.
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N-glycosylation state of TRPM8 protein revealed by terahertz spectroscopy and molecular modelling.
Mernea, M, Ulăreanu, R, Călboreanu, O, Chirițoiu, G, Cucu, D, Mihăilescu, DF
Biochimica et biophysica acta. General subjects. 2020;(7):129580
Abstract
TRPM8 member of the TRP superfamily of membrane proteins participates to various cellular processes ranging from Ca2+ uptake and cold sensation to cellular proliferation and migration. TRPM8 is a large tetrameric protein with more than 70% of its residues located in the cytoplasm. TRPM8 is N-glycosylated, with a single site per subunit. This work focuses on the N-glycosylation of TRPM8 channel that was previously studied by our group in relation to proliferation and migration of tumoral cells. Here, experimental data performed with deglycosylating agents assess that the sole glycosylation site contains complex glycans with a molecular weight of 2.5 kDa. The glycosylation state of TRPM8 in cells untreated and treated with a deglycosylating agent was addressed with Terahertz (THz) spectroscopy. Results show a clear difference between cells comprising glycosylated and deglycosylated TRPM8, the first presenting an increased THz absorption. Human TRPM8 was modelled using as templates the available TRPM8 and other TRPM channels structures. Glycosylations were modelled by considering two glycan structures with molecular weight close to the experiment: shorter and branched at the first sugar unit (glc1) and longer and unbranched (glc2). Simulation of THz spectra based on the molecular dynamics of unglycosylated and the two glycosylated TRPM8 models in lipid membrane and solvation box showed that glycan structure strongly influences the THz spectrum of the channel and of other components from the simulation system. Only spectra of TRPM8 with glc1 glycans were in agreement with the experiment, leading to the validation of glc1 glycan structure.
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RBCK1-related disease: A rare multisystem disorder with polyglucosan storage, auto-inflammation, recurrent infections, skeletal, and cardiac myopathy-Four additional patients and a review of the current literature.
Phadke, R, Hedberg-Oldfors, C, Scalco, RS, Lowe, DM, Ashworth, M, Novelli, M, Vara, R, Merwick, A, Amer, H, Sofat, R, et al
Journal of inherited metabolic disease. 2020;(5):1002-1013
Abstract
In this article, we report four new patients, from three kindreds, with pathogenic variants in RBCK1 and a multisystem disorder characterised by widespread polyglucosan storage. We describe the clinical presentation of progressive skeletal and cardiac myopathy, combined immunodeficiencies and auto-inflammation, illustrate in detail the histopathological findings in multiple tissue types, and report muscle MRI findings.
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Synthesis of novel α-glucans with potential health benefits through controlled glucose release in the human gastrointestinal tract.
Gangoiti, J, Corwin, SF, Lamothe, LM, Vafiadi, C, Hamaker, BR, Dijkhuizen, L
Critical reviews in food science and nutrition. 2020;(1):123-146
Abstract
The glycemic carbohydrates we consume are currently viewed in an unfavorable light in both the consumer and medical research worlds. In significant part, these carbohydrates, mainly starch and sucrose, are looked upon negatively due to their rapid and abrupt glucose delivery to the body which causes a high glycemic response. However, dietary carbohydrates which are digested and release glucose in a slow manner are recognized as providing health benefits. Slow digestion of glycemic carbohydrates can be caused by several factors, including food matrix effect which impedes α-amylase access to substrate, or partial inhibition by plant secondary metabolites such as phenolic compounds. Differences in digestion rate of these carbohydrates may also be due to their specific structures (e.g. variations in degree of branching and/or glycosidic linkages present). In recent years, much has been learned about the synthesis and digestion kinetics of novel α-glucans (i.e. small oligosaccharides or larger polysaccharides based on glucose units linked in different positions by α-bonds). It is the synthesis and digestion of such structures that is the subject of this review.