Relationship of oxidative stress and fibrinolysis in diabetes mellitus.

This study attempted to verify the existence of a relationship between oxidative stress documented by malondialdehyde (MDA) and superoxide dismutase (SOD) and fibrinolysis analysed by tissue plasminogen activator (tPA) and its inhibitor (PAI-1) in diabetes mellitus. Forty-seven patients with Type 1 (n = 27) and Type 2 (n = 20) diabetes were examined together with 20 non-diabetic controls. The following were analysed: plasma MDA concentration, SOD activity in erythrocytes, tPA activity and antigen, PAI-1 activity and antigen, fasting blood glucose, fructosamine, glycated haemoglobin (HbAlc), and urine albumin. SOD activity was decreased in patients with diabetes. This contrasted with an increased plasma MDA concentration especially in Type 2 diabetes as compared with Type 1 or healthy persons (p < 0.001). tPA activity was increased in both groups of patients with diabetes as compared to healthy persons (p < 0.001), PAI-1 activity was higher in Type 2 diabetes with vascular changes than in the remaining subgroups (p < 0.001). Multivariate analysis revealed a significant positive relationship between plasma MDA concentrations and PAI-1 antigen (r = 0.53, p < 0.001) and a negative relationship between SOD and tPA activities (r = -0.53, p < 0.01). We conclude that oxidative stress may modulate fibrinolytic properties in diabetes mellitus.

[Levels of lactic acid in type II diabetics treated with buformin]. / Hladiny kyseliny mlécné u diabetiku II. typu lécených buforminem.

The objective of the work was to assess the blood lactate levels in type 2 diabetics selected at random, treated for prolonged periods with buformin. 77% of the investigated group of diabetics (N = 70) had elevated blood lactate levels and 16% of them had hyperlactataemia (more than 5.0 mmol/l). In 33% patients with an originally elevated lactataemia after 12 weeks of discontinued buformin treatment the lactic acid blood levels reached normal values. The lactate levels declined significantly (by more than 25% of the original value) after 6 weeks without buformin treatment in another 45% of the diabetic patients. In 18% of the investigated patients, who had high lactate levels even after discontinuation of treatment, in two-thirds neither impaired function of the kidneys and liver nor cardiac disease or alcoholism were detected.

Early changes of serum N-acetyl-beta-glucosaminidase, tissue plasminogen activator and erythrocyte superoxide dismutase in relation to retinopathy in type 1 diabetes mellitus.

Biochemical markers of early changes that are characteristic for diabetic microangiopathy are not completely understood. We investigated activities of serum N-acetyl-beta-glucosaminidase (NAG), tissue plasminogen activator and erythrocyte superoxide dismutase in well defined groups of type 1 diabetic patients. Patients were selected on the basis of 4 year follow-up observation. Forty-two type 1 diabetic patients were subdivided into those without retinopathy (n = 13) throughout the study, those with newly developed or worsened retinopathy (n = 12) during 4 years and those with retinopathy already established at the beginning of the study and without evidence of its progression (n = 17). All diabetic patients had albustix-negative urine. A significant increase of the mean serum NAG activity during 4 years was found only in patients without retinopathy (P < 0.01) whereas no changes of the altered enzyme activities were present in patients with developing and established retinopathy. The mean activity of tissue plasminogen activator was elevated in all groups of diabetic patients compared with healthy subjects (P < 0.001). A significant positive correlation was found between plasminogen activator and serum NAG (r = 0.51, P < 0.01). Erythrocyte superoxide dismutase was higher in diabetic patients than in healthy persons (P < 0.01) but no differences were observed between the patients with or without retinopathy. Superoxide dismutase positively correlated with NAG (r = 0.57, P < 0.01). We conclude that early functional changes precede a morphological development of diabetic retinopathy as was evident from the altered enzyme activities.

[Biosensors in the clinical chemistry laboratory and in clinical medicine]. / Biosenzory v klinickochemické laboratori a v klinické medicíne.

Biosensors are up to date analytical instruments that make use of high sensitivity and specificity of biological receptors with physical or physico-chemical method of detection. The paper deals with following sensors: thermal, mass, surface plasmon resonators, optical sensors and biosensors, CHEMFETs, ISFETs, electrochemical sensors. Their principles and examples of use in investigation for biological and medical purposes are mentioned.