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Evaluation of the Dermal Irritancy of Chemicals
Published in David W. Hobson, Dermal and Ocular Toxicology, 2020
Canonico et al.79 wrote that sterile inflammatory lesions cause a nonspecific anabolic response of liver and nonparenchymatous liver cells (such as macrophages) resulting in the synthesis of a class of glycoproteins collectively termed acute-phase globulins. These proteins are thought to function by restricting tissue damage through inhibition of proteases released at sites of inflammation, by aiding in wound healing, by modulating blood clotting, by activating phagocytes, by promoting phagocytosis of necrotic tissue, and by modulating the immune response. These authors proposed that increased activity of glycosyltransferases in serum represented a nonspecific response to inflammation created by an increased demand for glycosylation of newly synthesized, acute-phase globulins. Serum levels of sialyltransferase, galactosyltransferase, a2-fucosyltransferase, and a3-fucosyltransferase were measured using scintillation spectroscopy after various tissue insult, including bacterial infection and skin burns. Variable, multifold increases in serum enzyme levels were observed, depending upon the type of tissue injury. The authors concluded that certain patterns of serum glycosyltransferase levels may be recognized as having diagnostic significance.
Antigenic Mimicry in Neisseria Species
Published in Helmut Brade, Steven M. Opal, Stefanie N. Vogel, David C. Morrison, Endotoxin in Health and Disease, 2020
Peter C. Giardina, Michael A. Apicella, Brad Gibson, Andrew Preston
Mandrell speculated on the potential evolutionary implications and possible benefit(s) of mimicking these paragloboside carbohydrate structures and proposed three possible selective advantages with regard to virulence and survival. First, antigenic mimicry may be important for evasion of the host immune response, as normal human serum does not contain antibodies to these self antigens (10–12). LOS has also been shown to inhibit complement-mediated killing and opsonization by normal human serum (13). Second, LOS may be involved in tissue specificity and invasion, based on the observation that human cells express Af-acetyllactosamine [Gal((β1→4)GlcNAc]-binding lectins, which are involved in intercellular communication and are part of the normal scavanging uptake system (14). Third, the action of bacterial glycosyltransferases released into tissues may alter host cell glycan-containing structures triggering a tissue-damaging immune response. These three hypotheses are not mutually exclusive and do not preclude other redundant virulence factors that may be expressed.
The Development of Improved Therapeutics through a Glycan- “Designer” Approach
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
With the availability of many oligosaccharyltransferases and multiple glycosyltransferases a chemoenzymatic glycosylation is becoming the method of choice. This is because the glycosylation can be controlled efficiently and is suitable for complex carbohydrates. Glycosyltransferases extend the sugar chain by the attachment of one monosaccharide at a time. For example, conjugation of GlcNAc to the lactose moiety of enkephalin was done using acetylglucosaminyltransferase derived from Neisseria species. With the current dynamic research in exploring new glycosyltransferases (e.g., database GlyTouCan) from different species, the chemoenzymatic glycosylation would be one of the most precise methods for glycosylation of therapeutics.
Determination of histopathological effects and myoglobin, periostin gene-protein expression levels in Danio rerio muscle tissue after acaricide yoksorrun-5EC (hexythiazox) application
Published in Drug and Chemical Toxicology, 2023
Yücel Başımoğlu Koca, Serdar Koca, Zübeyde Öztel, Erdal Balcan
We found that following yoksorrun (hexythiazox) treatments, myoglobin level was increased, depending on the skeletal muscle atrophy. This can point at two things: firstly, the acaricide may have reduced the oxygen content of the water. Secondly, oxygen may be insufficient in the muscle tissue due to muscle damage. Therefore, the unknown myoglobin gene expression mechanisms may be induced in intact and/or slightly damaged muscle cells to obtain the required oxygen. On the other hand, previous reports suggested that this pesticide is highly toxic to larvae of Tetranychus urticae but not harmful for deutonymph and adults (Dekeyser 2005, Leviticus et al.2020). More recently, Demaeght et al. (2014) proposed that hexythiazox binds to central pore region of chitin synthase enzyme and block the chitin translocation (Demaeght et al.2014). In a recent study, the regulatory effect of glycogen synthase and glycogen phosphorylase on chitin biosynthesis was investigated (Zhang et al.2019). Glycogen synthase is a key glycosyltransferase in the glycogen biosynthesis. Muscle glycogen is an essential energy source during mechanical action. To evaluate the glycogen content in hexythiazox-treated zebrafish skeletal muscle, we performed PAS technique. Our results indicated that glycogen is decreased upon the pesticide treatment. These data suggest that hexythiazox is not only responsible for the loss of muscle mass in zebrafish but also responsible for the decreasing of glycogen deposits in the skeletal muscles.
Echinocandins – structure, mechanism of action and use in antifungal therapy
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2022
Mateusz Szymański, Sandra Chmielewska, Urszula Czyżewska, Marta Malinowska, Adam Tylicki
The synthesis of β-(1,3)-d-glucan is catalysed by UDP-glucose (1,3)-d-glucan-β-(3)-d-glucosyltransferase, referred to as β-(1,3)-d-glucan synthase (EC 2.4.1.34)45. This enzyme uses UDP-glucose as a reaction substrate to form β-(1,3)-d-glycosidic bonds46. The enzyme is a transmembrane heteromeric glycosyltransferase consisting of at least two subunits. The Fks1p subunit (encoded by the FKS1, FKS2, and FKS3 genes) has a catalytic function, while the Rho1p subunit (belonging to the GTPase family) has a regulatory function. Echinocandins binding non-competitively to the Fks1p subunit of the enzyme inhibits its activity47,48. Blocking β-(1,3)-d-glucan biosynthesis leads to structural abnormalities of the fungal cell wall (Figure 13), resulting in growth inhibition or death by imbalance in osmotic pressure49. The fungicidal or fungistatic effects of echinocandins have been confirmed for most species of the Candida and Aspergillus genera50.
Prebiotic oligofructose protects against high-fat diet-induced obesity by changing the gut microbiota, intestinal mucus production, glycosylation and secretion
Published in Gut Microbes, 2022
Paola Paone, Francesco Suriano, Ching Jian, Katri Korpela, Nathalie M. Delzenne, Matthias Van Hul, Anne Salonen, Patrice D. Cani
In addition to the markers linked to goblet cells and mucins production, we investigated the expression of some glycosyltransferases. These are the enzymes responsible for the addition of several glycans to the protein core of the mucins thereby directly influencing the composition of the mucus layer.6,36 There are many types of glycosyltransferases, and each of them is specific for the addition of a single type of glycan in a precise position. By measuring the expression of glycosyltransferases involved in the elongation and branching process, we observed that the treatment with FOS significantly increased the N-acetylglucosaminyltransferases Gcnt1 in the cecum, Gcnt4 in the cecum and colon and B3gnt6 in the colon, when compared to HFD and CT group (Figure 4a-c). The galactosyltransferases C1galt1 and its chaperone C1galt1c1 significantly increased in the cecum and colon (Figure 4d,e). The treatment with FOS also influenced the expression of the glycosyltransferases involved in the termination of the glycan chain. Indeed, we observed a significant increase of the fucosyltransferases Fut1 and Fut2 in the jejunum, ileum and colon and Fut8 only in the cecum and colon (Figure 4f-h). Finally, we observed a significant increase of the sialyltransferases St3gal1 and St3gal3 in the colon and a significant decrease of St3gal4 and St6galnac2 in the cecum (Figure 4i-m).