Glycosylation is the most common chemical process of protein modification and occurs in every living cell. Disturbances of this process may be either congenital or acquired. Congenital disorders of glycosylation (CDG) are a rapidly growing disease family, with about 50 disorders reported since its first clinical description in 1980. Most of the human diseases have been discovered recently. CDG result from defects in the synthesis of the N- and O-glycans moiety of glycoproteins, and in the attachment to the polypeptide chain of proteins. These defects have been found in the activation, presentation, and transport of sugar precursors, in the enzymes responsible for glycosylation, and in proteins that control the traffic of component. There are two main types of protein glycosylation: N-glycosylation and O-glycosylation. Most diseases are due to defects in the N-glycosylation pathway. For the sake of convenience, CDG were divided into 2 types, type I and II. CDG can affect nearly all organs and systems. The considerable variability of clinical features makes it difficult to recognize patients with CDG. Diagnosis can be made on the basis of abnormal glycosylation display. In this paper, an overview of CDG with a new nomenclature limited to the group of protein N-glycosylation disorders, clinical phenotype and diagnostic approach, have been presented. The location, reasons for defects, and the number of cases have been also described. This publication aims to draw attention to the possibility of occurrence of CDG in each multisystem disorder with an unknown origin.
Glycosylation is a form of post-translational modification of proteins and occurs in every living cell. The carbohydrate chains attached to the proteins serve various functions. There are two main types of protein glycosylation: N-glycosylation and O-glycosylation. In this paper, we describe the O-glycosylation process and currently known congenital disorders of glycosylation associated with defects of protein O-glycosylation. This process takes place in the cis Golgi apparatus after N-glycosylation and folding of the proteins. The O-glycosylation is essential in the biosynthesis of mucins, the formation of proteoglycan core proteins and blood group proteins. Most common forms of O-glycans are the mucin-type glycans. There are more than 20 known disorders related to O-glycosylation disturbances. We review 8 of the following diseases linked to defects in the synthesis of O-xylosylglycans, O-N acetylgalactosaminylglycans, O-xylosyl/N-acetylglycans, O-mannosylglycans, and O-fucosylglycans: multiple exostoses, progeroid variant of Ehlers-Danlos syndrome, progeria, familial tumoral calcinosis, Schneckenbecken dysplasia, Walker-Warburg syndrome, spondylocostal dysostosis type 3, and Peter's plus syndrome. Causes of these diseases include gene mutations and deficiency of proteins (enzymes). Their diagnosis includes syndromic presentation, organ-specific expression and laboratory findings.
The common pathway leading to liver fibrosis and cirrhosis is growing deposition of extracellular matrix (ECM). It results from molecular and histological rearrangement of collagens, glycoproteins and hyaluronans. Hyaluronic acid is a chief component of the extracellular matrix of connective tissues and plays the main structural role in the formation of ECM. The most important organ involved in the synthesis of hyaluronic acid is the liver. In this paper the meaning of hyaluronic acid in the diagnostics of liver diseases is discussed. Here, we focus on the described changes of hyaluronic acid concentration in the pathological processes of the liver, including alcoholic and non-alcoholic liver diseases. The results of published clinical studies have shown its high diagnostic sensitivity, which probably enables its application in laboratory diagnosis.
Disturbances of hemostatic system are commonly observed in chronic kidney disease (CKD) patients. Along with CKD progression, the levels of tryptophan-derived uremic toxins increase, including quinolinic acid (QA). Objective of the study was to evaluate the effect of QA, a representative of tryptophan metabolites, on coagulation and fibrinolytic activity in male Wistar rats in vivo and platelet activity in vitro. Rats received QA dissolved in drinking water in doses of 3, 10, and 30 mg/kg (or water, VEH) for 14 days. Next, the following parameters were measured in the rat‘s whole blood or plasma ex vivo: thromboelastometric (ROTEM) parameters, standard coagulation parameters and fibrinolytic parameters. To evaluate the direct effect of QA on coagulation and platelet activity, blood from control rats was drawn and analyzed in vitro in the following scheme: samples of whole blood were incubated with QA (100µM) before thromboelastometric (ROTEM) analysis and collagen-induced platelet aggregation, or samples of platelet rich plasma (PRP) were incubated with QA (100µM, 1 and 2mM) 10 minutes before collagen (1µg/ml) or ADP (10µM)-induced platelet aggregation. QA administrated for 14 days in drinking water had no effect per se on activation of coagulation and fibrinolytic parameters in rats ex vivo. Similarly, no changes were observed in a whole blood incubated directly with QA regarding coagulation parameters or collagen-induced platelet aggregation. QA inhibited ADP-induced platelets aggregation in PRP only at higher concentrations of 1 and 2 mM and when aggregation was initiated by the addition of 10µM ADP in vitro.
Aim: The aim of the current study was to assess the serum levels of insulin-like growth factor-1 (IGF-1) and ghrelin in hypertrophied adenoids in children suffering with or without otitis media with effusion before and after adenoidectomy. Material and methods: Serum IGF-1 and ghrelin concentrations were measured with specific enzyme-linked immunoassay (ELISA) methods. The study was carried out in 20 children with otitis media with effusion. The reference group comprised 24 children with hypertrophied adenoid, while control group included 19 children. Results: This mean values of IGF-1 in children with otitis media with effusion and children with hypertrophied adenoid before adenoidectomy were significantly lower than those found in healthy children. Serum levels of IGF-1 were higher after adenoidectomy. There was a significant difference of serum ghrelin levels between both examined groups and the control group. Conclusion: Our results suggest that adenoidectomy in children with hypertrophied adenoids and in children with otitis media with effusion significantly increases the level of IGF-1 in serum compared to before surgery through the effect of the GH-IGF-1 axis, which could contribute to children’s growth.
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