Immunohistochemical Features of Different Types of Unstable Atherosclerotic Plaques of Coronary Arteries.

We performed a complex morphological study of samples of different types of unstable atherosclerotic plaques obtained from 33 men with occlusive coronary atherosclerosis, who underwent coronary artery endarterectomy during coronary artery bypass surgery. In the samples, expression of MMP-2 and MMP-9, collagen IV, CD31, CD34, factor VIII, and actin of smooth muscle cells was evaluated by morphometric and immunohistochemical methods. The maximum expression of MMP-9 was found in unstable plaques of the lipid type, where it 1.4- and 1.24-fold surpassed the corresponding levels in plaques of the inflammatory-erosive and degenerative-necrotic types. Unstable plaques of the degenerative-necrotic type are characterized by the most intensive expression of collagen IV in comparison with plaques of the inflammatory-erosive and lipid types (by 2.8 and 2.2 times, respectively). The maximum neovascularization was detected in inflammatory-erosive plaques, which was confirmed by enhanced expression of CD31 and CD34 markers in comparison with plaques of the lipid (by 7.6 and 18.95 times, respectively) and degenerative-necrotic (by 31.1 and 39.8 times) types.

Immunohistochemical Phenotypes of Stable and Unstable Occlusive Atherosclerotic Plaques in Coronary Arteries.

We performed a complex morphological analysis of atherosclerotic plaques obtained from 68 men with coronary atherosclerosis during coronary bypass surgery with endarterectomy. The expression of MMP-2 and MMP-9, collagen IV, CD31, CD34, factor VIII, and of smooth muscle cell actin was measured in the samples by morphometric and immunohistochemical methods. The expression of MMP-2 and MMP-9 as well as the intensity of neoangiogenesis estimated by the expression of CD31, CD34, and factor VIII in unstable plaques was significantly higher than in stable ones. Immunohistochemical analysis showed more intensive collagen IV expression in stable plaques. The observed differences in immunohistochemical phenotypes of stable and unstable atherosclerotic plaques reflect peculiarities of morphogenesis of atherosclerotic foci in the coronary arteries determining their further development.

[Changes of Content of Matrix Metalloproteinases and Their Tissue Expression in Various Types of Atherosclerotic Plaques].

AIM: to investigate diagnostically significant for atherosclerotic plaques (ASP) of various types parameters of activity of matrix metalloproteinases (MMP-3, MMP-7, MMP-9) in homogenates, as well as tissue expression of MMP-2, MMP-9 and collagen type IV. MATERIALS AND METHODS: We included in this study 54 men with coronary atherosclerosis without acute coronary syndrome who underwent coronary artery bypass surgery with endarterectomy. In the obtained samples we determined levels of MMP-3, MMP-7, and MMP-9 (by enzyme immunoassay), as well as tissue expression of antibodies to MMP-2, MMP-9 and collagen type IV. RESULTS: In unstable plaques we observed increased activity of MMP-7 and MMP-9, significant increase of tissue expression of MMP-2 and MMP-9, and decreased expression of type IV collagen. Of three types of unstable ASP the highest tissue expression of MMP-9 was found in plaques of lipid type compared with plaques of necrotic and inflammatory-erosive types. Expression of type IV collagen predominated in plaques of necrotic type. CONCLUSION: The data obtained allows us to speak about tissue expression of collagen as the marker of fibrous cap stability; the presence of metalloproteinases in necrotic detritus, collagen fibers, and cellular elements can characterize an ASP as unstable or being in the transitional structural state. The immunohistochemical method helps to detect structural elements that characterize instability in various types of ASP.

Ultrastructural and metabolic features of stress-adaptive rearrangements of myocardium in infants after surgery-induced up-regulation of lipoperoxidation processes.

Surgical correction of complicated congenital heart disease in infants is terminated by postischemic reperfusion of myocardium accompanied with closure of more than 20% microvessels in the coronary bed by edematous endothelial cells, their bleb-like fragments, and aggregates of the blood formed elements. Degradation of the transmission capacity of the coronary microvessels developed in parallel with moderation of activity of the antiradical protection enzymes and positively correlated with the level of LPO secondary products, whose elevation during the surgery stages was not reduced by catalase activation.

Ultrastructural organization of capillaries in various compartments of the dog heart in artificial immersion hypothermia.

Similarity of the structural characteristics of perfusion capacity of right-atrial and left-ventricular capillaries of the dog heart in health were detected, the capillaries differing significantly by size and by the majority of the morphometrical values. Exposure of animals to hypothermia induces different ultrastructural responses of the capillaries in two compartments of the heart: the perfusion characteristics of the right atrium deteriorate and the morphometrical parameters of endotheliocytes change, while in the left ventricle the population composition of endothelial cells changes significantly (the percentage of cells of the main type reduces, while the share of dark cells increases).

Ultrastructure of myocardial capillary endothelium in children with congenital heart disease.

Cardiosurgical stress initiates endothelial injury of the colliquation necrosis type (without activating coagulation necrosis) in coronary capillaries of infants aged under 1 year. The dark cells exhibited high tolerance to operation stress in the presence of labile ultrastructural response of endothelial cells of the main and light types. The percentage of dark cells does not change during surgical intervention, which is a sign predicting a favorable course of the postoperative period.

Ultrastructural analysis of secretory granules of myocardial capillary endothelium in cardiosurgical stress.

In patients with chronic myocardial tissue hypoxia irrespective of the disease (Fallot's tetralogy, coronary disease) factors of cardiosurgical stress initiate a drop of secretory production in coronary capillary endothelium and obstruction of the intravascular space by blood cells. In children the peak of exocytosis of secretory granules coincides with the period of aortic occlusion, while in adults it is attained at the stage of reperfusion.

Changes in myocardial metabolism and ultrastructure of myocardial microvessels during pharmacological and cold cardioplegia under hypothermic conditions without perfusion.

A combination of pharmacological and cold cardioplegia in with hypothermia without perfusion in open-heart surgery guarantee the reversible character of shifts in energy and free radical balance in the myocardium. However, this procedure can impair coronary micricirculation due to structural and functional changes in microvessel endothelium. Our results demonstrate that new cytoprotective approaches are extremely needed for cardiac protection during surgery.

Effect of calcium antagonists on ultrastructure of myocardial microvessels during open heart surgery under conditions of pharmacological and cold cardioplegia.

Ultrastructure of myocardial microvessels was examined during surgical correction of congenital heart disease (ventricular septal defect) under conditions of cold and pharmacological low-potassium cardioplegia without perfusion. Addition of calcium antagonist verapamil to cardioplegic solution prevented postischemic damage to vascular and perivascular structures occurring during reperfusion and body temperature rise.

Experimental studies on the endothelium ultrastructure of heart capillaries under moderate (28-30 degrees) and deep (22-24 degrees) hypothermia without perfusion.

Ultrastructural changes in endothelial cells (EC) of myocardial capillaries were studied in 24 dogs which underwent hypothermia without perfusion. Biopsy specimens for electron microscopy were taken from the left ventricle of each dog in the control group, during anesthesia (prior to active cooling), and at the end of moderate (28-30 degrees ) and deep (22-24 degrees ) artificial body cooling. The following morphological types of the EC were identified both in the control group and in all test groups: those with moderately dense cytoplasm, light, dark, and irreversibly damaged cells. Dark cells showed increased numbers of plasmalemmal vesicles and appeared to be more transport-specialized as opposed to other types. In all stages of the experiment the amount of dark cells continuously increased (to 23.80, 34.62, and 47.17%, respectively). On cooling to 28-30 degrees, subcellular manifestation of reduced synthetic activity of organelles (nucleus, Golgi complex, and rough endoplasmic reticulum) was observed in all types of the EC. These changes persisted, or even increased, at the end of deep hypothermia. The transport activity of the EC changed differently in three experimental groups in all cell types. Micropinocytotic activity increased under spontaneous mild hypothermia (34-35 degrees ) during anesthesia and tended to decrease with subsequent artificial lowering of the temperature to 22-24 degrees. These ultrastructural changes seem to make up an integral part of the process of capillary endothelium adaptation to body surface cooling, and they might contribute to the development of tolerance to subsequent ischemic exposure during cardiac arrest.