Fibrinogen Modification and Fibrin Formation in Patients with an End-Stage Renal Disease Subjected to Peritoneal Dialysis.

End-stage renal disease (ESRD) is a condition accompanied by increased inflammation, oxidative stress, risk of cardiovascular complications, and coagulopathies. The structure of fibrinogen and characteristics of fibrin from plasma samples of ESRD patients on peritoneal dialysis (PD) was investigated. Fibrinogen from ESRD patients had a higher degree of carbonylation than fibrinogen from healthy individuals. The Aα chain was the most susceptible to oxidation, followed by the Bß chain, whereas the γ-chain was the most resistant to oxidation. Spectrofluorimetric analysis suggested a higher extent of modification of amino acid side chains in fibrinogen from ESRD patients. The tertiary structure of fibrinogen was more affected than its secondary structure. The kinetics (time and rate) of fibrinogen coagulation did not differ between the tested groups. Fibrin prepared from the isolated fibrinogen had a similar structure in both groups. Our results confirm that oxidation and structural alterations of fibrinogen occur in ESRD patients on PD, although these modifications produce no direct effect on the fibrin formation. Taking into account that some patients suffer from bleeding, whereas others develop thrombotic complications, further research on this subject is required to identify other components and processes that contribute to the outcome.

Enhanced Platelet Sensitivity to IGF-1 in Patients with Type 2 Diabetes Mellitus.

Diabetes mellitus is characterized by increased platelet activation which is determined by many factors including changes in the expression of membrane proteins. The aim of this study was to investigate the sensitivity of human platelets to the insulin-like growth factor (IGF) system in patients with poorly controlled type 2 diabetes mellitus (DM2). Ligand binding was analyzed using 125I-labelled IGF-1 and insulin, and relative expression of insulin-like growth factor 1 receptor (IGF-1R) and insulin receptor (IR) was evaluated by Western blotting. Platelet aggregation in the presence of IGF-1 was studied by the plate aggregometry assay. We found that platelets from DM2 patients exhibited significantly higher IGF-1 binding and upregulation of IGF-1R expression in comparison with healthy individuals. Both insulin binding and IR expression were lower in the DM2 group, but the differences with the healthy control were statistically insignificant. The potentiating effect of IGF-1 on the thrombin-induced activation of platelets was detected in both groups but was significantly more pronounced in the DM2 patients. The initial rate of platelet activation in the presence of IGF-1 positively correlated with the concentration of glycated hemoglobin. Platelets isolated from DM2 patients displayed elevated expression of the IGF-1R subunits, which might have contributed to the higher sensitivity of these cells to IGF-1 in thrombin-initiated aggregation by increasing the rate of platelet activation. However, further experiments are needed to investigate the role of IGF-1 in thrombotic complications that usually accompany diabetes.

Analysis of Four Circulating Complexes of Insulin-Like Growth Factor Binding Proteins in Human Blood during Aging.

The primary role of insulin-like growth factor binding proteins (IGFBPs) is to regulate availability of IGFs for interacting with receptors, but IGFBPs perform IGF-independent actions as well. The availability and activity of IGFBPs in the circulation is influenced primarily by their concentration and structural modifications, but possibly also by interaction with major plasma proteins such as transferrin, alpha-2-macroglobulin (α2M), and fibrinogen. Four types of circulating IGFBP complexes were examined in this study by immuno- and ligand-binding assays in adults of different age. The amounts of IGFBP-3/transferrin and IGFBP-1/fibrinogen complexes were similar in middle- and old-aged persons, whereas the amounts of IGFBP-1 (or -2)/α2M monomer complexes were lower in the old-aged group and negatively correlated with total IGFBP-1 (or -2) amounts in blood. In contrast to IGFBP-1, IGFBP-2 was present in significantly greater quantities in complexes with α2M dimer than α2M monomer in older individuals. IGFBP complexes did not bind 125I-labeled IGF-I in amounts detectable by ligand blotting. According to the results of this study, the quantities of IGFBP-1 and IGFBP-2, which interact with α2M, are age-dependent and, in the case of complexes with α2M monomer, they are negatively correlated with the total circulating levels of these two IGFBPs.

Interaction between Fibrinogen and Insulin-Like Growth Factor-Binding Protein-1 in Human Plasma under Physiological Conditions.

Fibrinogen is a plasma glycoprotein and one of the principle participants in blood coagulation. It interacts with many proteins during formation of a blood clot, including insulin-like growth factors (IGFs) and their binding proteins (IGFBP). Fibrinogen complexes were found as minor fractions in fibrinogen preparations independently of the coagulation process, and their presence influences the kinetics of polymerization. The idea of this work was to investigate whether fibrinogen in human plasma interacts with IGFBPs independently of the tissue injury or coagulation process. The results have shown that fibrinogen forms complexes with IGFBP-1 under physiological conditions. Several experimental approaches have confirmed that complexes are co-isolated with fibrinogen from plasma, they are relatively stable, and they appear as a general feature of human plasma. Several other experiments excluded the possibility that alpha-2 macroglobulin/IGFBP-1 complexes or IGFBP-1 oligomers contributed to IGFBP-1 immunoreactivity. The role of fibrinogen/IGFBP-1 complexes is still unknown. Further investigation in individuals expressing both impaired glucose control and coagulopathy could contribute to identification and understanding of their possible physiological role.

The influence of the tooth preparation finish line position on the expression of matrix metalloproteinase-9 and the presence of periodontopathogens in the gingival crevicular fluid.

OBJECTIVE: The objective of the study was to determine the concentration of matrix metalloproteinase 9 (MMP-9) and changes in the presence of periodontopathogens in the gingival crevicular fluid before and after tooth preparation with the subgingival and equigingival finish line position. PATIENTS AND METHODS: The clinical prospective study included 20 subjects with an indication for upper canine preparation, with the subgingival (group 1) and equigingival finish line (group 2). Samples were taken in four observation intervals: 5 minutes before (control samples), as well as 15 minutes, 24 and 72 hours after tooth preparation (experimental samples). Measurement of MMP-9 was done using Enzyme-linked Immunosorbent Assay (ELISA). The presence of bacteria in the gingival fluid was proven by the Polymerase chain reaction (PCR) analysis. RESULTS: The MMP-9 values did not differ statistically significantly between the groups (p=0.524). The MMP-9 values showed a statistically significant difference in the given observation period (p<0.001) with a significant linear increase in values (p<0.001). A significant quadratic trend recorded a decrease in the MMP-9 values 15 minutes after preparation, and an increase 24 hours after preparation, without a significant difference in the interaction between groups (p=0.392). After preparation, a significant difference in the presence of periodontopathogens was confirmed, i.e., a decrease in the presence of Prevotella intermedia (p=0.025) and Tannerella forsythia (p=0.016) in group 1, and an increase in the presence of Aggregatibacter actinomycetemcomitans in both groups (p=0.029, p=0.026). CONCLUSIONS: The study is a good basis for determining the influence of tooth preparation on gingival inflammation, with therapeutic (choice of preparation technique) and preventive significance regarding the protection of the periodontal tissue from possible iatrogenic damage.

Adverse reactions to denture resin materials.

Irrespective of the new generation of dental materials, acrylates still have a wide indication field. Although they are classified as biomaterials, acrylates can have both local and systemic side effects. The individual components of the acrylic materials may leave the dental restorations and diffuse into saliva. The aim of this study was to point out the potentially toxic components of acrylic dental materials, as well as their possible adverse effects on oral tissues and the organism in general. The paper was based on the assumption that the appropriate selection of the type of acrylic material and the proper method of their preparation reduce their adverse effects to a minimum, which was proven using literature data.