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.

Oxidation of placental insulin and insulin-like growth factor receptors in mothers with diabetes mellitus or preeclampsia complicated with intrauterine growth restriction.

Placental insulin receptor (IR) and insulin-like growth factor receptors (IGFRs) are essential for fetal growth. We investigated structural changes of these receptors exposed to increased oxidative stress in mothers diagnosed with diabetes mellitus (DM) or preeclampsia (PE) complicated with intrauterine growth restriction. Increased amount of IR and decreased amounts of IGF1R and IGF2R were found in both pathologies, accompanied by significant elevation in protein carbonyls. When isolated receptors were examined, increased carbonylation of IR and IGF1R in PE placentas was detected, whereas the amounts of carbonylated IR and IGF1R were similar in DM and healthy placentas. Carbonylation status of IGF2R did not change due to pathology, confirming the detrimental role of primary structure and conformation in oxidative susceptibility. Ligand binding was similar in all three groups of samples and did not seem to be affected by receptor oxidation. Since babies delivered by mothers with PE were smaller than the referent population, increased carbonylation of receptors might have affected downstream receptor signaling post-ligand binding.