[Myeloperoxidase activity in blood plasma as a criterion of therapy for patients with cardiovascular disease]. / Aktivnost' mieloperoksidazy v plazme krovi kak kriterii éffektivnosti lecheniia patsientov s serdechno-sosudistymi zabolevaniiami.

A significant increase in the myeloperoxidase (MPO) activity has been found in plasma of patients with stable angina and with acute coronary syndrome (ACS) in comparison with the control group. MPO concentration was significantly increased in plasma of ACS patients. Reduced MPO activity in the treated ACS patients correlated with a favorable outcome of the disease. Generally, changes in plasma MPO concentration coincided with changes in lactoferrin concentration thus confirming the role of neutrophil degranulation in the increase of plasma concentrations of these proteins. The increase in MPO activity was obviously determined by modification of the MPO protein caused by reactive oxygen species and halogen in the molar ratio of 1 : 25 and 1 : 50. The decrease in plasma MPO activity may be associated with increased plasma concentrations of the physiological inhibitor of its activity, ceruloplasmin, and also with modification of the MPO protein with reactive oxygen species and halogen at their molar ratio of 1 : 100 and higher. Thus, MPO activity may be used for evaluation of effectiveness of the treatment of cardiovascular diseases.

[Antioxidant status and glutathione redox potential of erythrocytes in patients with acute coronary syndrome].

Indicators of oxidative stress (OS), systemic inflammation, metabolism and redox status of glutathione (GSH) were investigated and compared in patients with ST-segment elevation myocardial infarction on electrocardiograms (STEMI), and patients with unstable angina (UA). The elevated and decreased myeloperoxidase level, superoxide dismutase activity, and moderate increased plasma levels of interleukin-6, while maintaining the antioxidant potential, were found in Group 1. Disorders in pro-/antioxidant balance and systemic inflammatory response were manifested in UA. Increased GSH concentration (and total GSH) in erythrocytes has been established for STEMI patients and the decreased GSH for UA patients. Thus, a significant shift of erythrocytes redox to oxidization and increase (unlike STEMI patients) of glutathione peroxidase activity were recorded. Mechanisms of the pro- and antioxidant functions of red blood cells in acute coronary syndrome are considered. The role of red blood cell glutathione to provide more oxidized intravascular environment for S-glutathionylation and optimization of redox signaling in target cells is pronounced.

Measurement of plasma hemoglobin peroxidase activity.

We described a spectrophotometric method for measuring hemoglobin peroxidase activity in human plasma using o-dianisidine (o-DA) as the substrate and myeloperoxidase specific inhibitor 4-aminobensoic acid hydrazide (ruling out the probable contribution of myeloperoxidase to the measured parameter value). The optimal conditions (pH 5.5; 2 mM H2O2) have been determined, at which hemoglobin makes the main contribution to plasma oxidation of o-DA. A significant positive correlation between hemoglobin peroxidase activity measured by the spectrophotometric method and hemoglobin level measured by the pyridine hemochromogenic method has been detected (r=0.624; p<0.01) in plasma specimens from 16 donors. Plasma hemoglobin peroxidase activities were measured in healthy individuals and patients with type 2 diabetes mellitus and coronary heart disease. High plasma hemoglobin peroxidase activities in both groups of patients indicates disorders in the mechanisms of clearance of hemoglobin and its highly reactive derivatives and can serve as specific markers of diseases associated with oxidative stress.

Functional activity of neutrophils in diabetes mellitus and coronary heart disease: role of myeloperoxidase in the development of oxidative stress.

We performed a comparative analysis of functional activity of neutrophils in patients with type 2 diabetes mellitus with and without symptoms of CHD. Enhanced H2O2 production by neutrophils in response to N-formyl-Met-Leu-Phe (fMLP) was found in patients with type 2 diabetes mellitus. In patients with type 2 diabetes mellitus associated with CHD, fMLP-induced release of myeloperoxidase from azurophilic granules of neutrophils was reduced and plasma myeloperoxidase level was elevated. Increased peroxidase activity of myeloperoxidase, reduced plasma catalase activity, and increased levels of TBA-reactive lipid peroxidation products and oxidized glutathione were detected in patients of both groups. Since myeloperoxidase is an important neutrophilic mediator of oxidative stress, its increased activity in the blood can be an additional marker of oxidative stress and cardiovascular risk in patients with diabetes mellitus.