Prospects for the use of indicators of sialic acid metabolism in medicine (review of literature)

Sialic acids (SA) determine the degree of molecular hydrophilia, relieve binding together and their transportation, they increase mucin viscosity, stabilize the protein and membrane structure. Apart from that, SA are structural components of gangliosides participating in the formation of the outer layer of the plasma membrane. The degree of silyliation of glycoproteins and glycolipids is an important factor of molecular recognition in the cell, between the cells, between a cell and territorial matrix, as well as between a cell and some outer pathogenic factors. They can either mask the sites of recognition or be determinants of recognition. The most well-studied enzymes taking part in the SA metabolism and sialo-containing compounds are N-acetylneuraminate, cythydiltransferase, sialyltransferase, sialydase, aldolase SA and sialyl-O-acetylesterase. Numerous investigations have shown that aberrant sialylation is a specific feature of various changes and disorders of metabolism. Besides that, sialic acids are the first point of contact for different pathogenic microorganisms and the host's body due to their presence on the external surface of the cells and tissue of the mucous membrane. That is why the study of the above-mentioned various sialic acids fractions as well as of the activity of the enzymes participating in their metabolism in the blood plasma and tissues, and of the influence on the activity of these enzymes with the help of medicine can make an essential contribution to the diagnosis and treatment of many diseases.

Influence of exogenous and endogenous factors on the quality of the preanalytical stage of laboratory tests (review of literature)

A literature review in the article presents an analysis of the influence of endogenous and exogenous factors on quality of preanalytical phase of laboratory testing. The review shows significance of external and internal factors influencing blood samples at preanalytical phase of laboratory testing. Among the exogenous factors considered: phlebotomy, test tubes for samples, transportation and storage. A number of factors exist at this phase that significantly affect test results. We examined these aspects of phlebotomy process: staff training, disinfectant contamination, needle diameter, needle material contamination. The review considers possible contamination with tube components and the importance of choosing the right anticoagulants and excipients. Transportation and storage of biological samples can be a source of errors at the preanalytical phase of laboratory testing. We analyzed the problem of determining the stability of analytes during storage and aspects of transportation samples by modern means. Among the endogenous factors considered: hemolysis, lipemia, icterricity, cell metabolism.. Hemolysis is one of the most frequent consequences of errors at the preanalytical phase. We analyzed importance of choosing a method for identifying hemolized tubes and the heterogeneity of bias results on different analytical systems. The review shows contribution of various classes of lipoproteins to turbidity of sample, possible preanalytical errors and impact on analytical tests. We examined possible effects of high bilirubin concentrations on analyte measurements. In the review, we also examined metabolism of some cells and its effect on samples.

[Changes in the system of antioxidant blood defence in newborns with different pathology]

Blood antioxidant enzymes (superoxide dismutase, catalase, ceruloplasmin) were investigated in gestational ages and diseases. Low activity of blood superoxide dismutase and catalase were observed in premature babies and in newborns after acute and chronic hypoxia. In hemolytic disease the activity of antioxidant enzymes of newborns was significantly higher than in healthy infants. This work demonstrates advantages of haemosorbtion compared to exchange blood transfusion. So the antioxidant activity in blood, decreased after blood transfusion, remained at a high level after haemosorbtion. Any deficiency of antioxidant enzymes in newborns may lead to toxyc oxygen effects. Antioxidants are potential therapeutic agents in the above mentioned conditions.

[Glycation of proteins and methods of its assessment]

Glycation of purified preparations of amino acids, hemoglobin and albumin has been studied. The content of glycated blood proteins in children with different diseases (diabetes mellitus, thyroid gland function disturbances, obesity, neurodermititis) has been determined. Application of the protein glycation for diagnosis and prediction of diseases is proved to be expedient.

[Glycosylated hemoglobins in humans and various animal species]

The quantity of glycosylated hemoglobins and proteins from blood serum of rabbits, fishes, minks and guinea-pigs is investigated. The content of glycosylated hemoglobins in newborns and healthy adults is compared with that of animals. The colorimeter method of defining glycosylate proteins is used in the test. Three groups are isolated by the quantity of glycosylated proteins. These are the following: the first group with the low content--minks, rabbits, guinea-pigs, the second one with the mean content--healthy newborn and grown-ups and the third group with the high content--fishes. The obtained results evidence for possibility of protein glycosylation not only in human beings but also in animals and fishes.

[Increased efficacy of allogenic bone marrow transplantation]

Experiments made in vivo and vitro have demonstrated that conservation of allogeneic hemopoietic tissue with glycerin brings about a decrease in transplatation, homologous activity of T lymphocytes. Allogeneic bone marrow conserved with glycerin compares very favourably with freshly prepared allogeneic bone marrow since the transplant-versus-host reaction is attenuated under the effect of glycerin. Moreover, it shows a higher proliferative activity. The glycerin-induced reduction of the inactivating effect of lymphocytes against non-syngeneic colony-forming units enables the conserved bone marrow to be transplanted from several donors.