Vasa Vasorum Lumen Narrowing in Brain Vascular Hyalinosis in Systemic Hypertension Patients Who Died of Ischemic Stroke

Ischemic stroke is a major cause of death among patients with systemic hypertension. The narrowing of the lumen of the brain vasculature contributes to the increased incidence of stroke. While hyalinosis represents the major pathological lesions contributing to vascular lumen narrowing and stroke, the pathogenic mechanism of brain vascular hyalinosis has not been well characterized. Thus, the present study examined the postmortem brain vasculature of human patients who died of ischemic stroke due to systemic hypertension. Hematoxylin and eosin staining and immunohistochemistry showed the occurrence of brain vascular hyalinosis with infiltrated plasma proteins along with the narrowing of the vasa vasorum and oxidative stress. Transmission electron microscopy revealed endothelial cell bulge protrusion into the vasa vasorum lumen and the occurrence of endocytosis in the vasa vasorum endothelium. The treatment of cultured microvascular endothelial cells with adrenaline also promoted the formation of the bulge as well as endocytic vesicles. The siRNA knockdown of sortin nexin-9 (a mediator of clathrin-mediated endocytosis) inhibited adrenaline-induced endothelial cell bulge formation. Adrenaline promoted protein-protein interactions between sortin nexin-9 and neural Wiskott–Aldrich syndrome protein (a regulator of actin polymerization). Spontaneously hypertensive stroke-prone rats also exhibited lesions indicative of brain vascular hyalinosis, the endothelial cell protrusion into the lumen of the vasa vasorum, and endocytosis in vasa vasorum endothelial cells. We propose that endocytosis-dependent endothelial cell bulge protrusion narrows the vasa vasorum, resulting in ischemic oxidative damage to cerebral vessels, the formation of hyalinosis, the occurrence of ischemic stroke, and death in systemic hypertension patients.

Transmission Electron Microscopy Study of Mitochondria in Aging Brain Synapses

The brain is sensitive to aging-related morphological changes, where many neurodegenerative diseases manifest accompanied by a reduction in memory. The hippocampus is especially vulnerable to damage at an early stage of aging. The present transmission electron microscopy study examined the synapses and synaptic mitochondria of the CA1 region of the hippocampal layer in young-adult and old rats by means of a computer-assisted image analysis technique. Comparing young-adult (10 months of age) and old (22 months) male Fischer (CDF) rats, the total numerical density of synapses was significantly lower in aged rats than in the young adults. This age-related synaptic loss involved degenerative changes in the synaptic architectonic organization, including damage to mitochondria in both pre- and post-synaptic compartments. The number of asymmetric synapses with concave curvature decreased with age, while the number of asymmetric synapses with flat and convex curvatures increased. Old rats had a greater number of damaged mitochondria in their synapses, and most of this was type II and type III mitochondrial structural damage. These results demonstrate age-dependent changes in the morphology of synaptic mitochondria that may underlie declines in age-related synaptic function and may couple to age-dependent loss of synapses.

[Functional morphology of ischemic cardiomyopathy]

OBJECTIVE

To show that ischemic cardiomyopathy (ICM) that is generally believed to be a variant of chronic heart disease (CHD) and an analogue of chronic heart failure is an initial stage and the background of all further forms of CHD.

SUBJECTS AND METHODS

Sixty cardiac biopsies obtained from patients during aortocoronary bypass surgery for CHD and myocardia from 55 rabbits in which the investigators simulated atherosclerosis over time, as well as acute, transient, and recurrent coronary insufficiency after vasopressin administration were examined. A number of adequate histological, histochemical, and immunohistological procedures, electron microscopic and electron histochemical studies, and morphometry were employed. The investigators made biochemical monitoring of blood cholesterol and triglyceride levels and ECG monitoring in the animals had received intravenous vasopressin.

RESULTS

The authors have indicated that CHD begins with endothelial changes in the trophic component of the microhemocirculatory bed, which gives rise to its impaired blood flow and to hypoxia at the level of the myocardial structural and functional unit--fascicules. Over time, the disease develops a set of processes that cause damage to microvessels, cardiomyocytes, stroma, lymph capillaries, and nerve endings and changes in secretion. Compensatory and adaptive responses that long mask the symptoms of damage to the vascular bed and myocardial tissue take place simultaneously. The occurring lesions result in irregular diffuse cardiosclerosis, micro- and lymphocirculatory, innervation, and conduction disturbances, and irregular cardiomyocyte damage. The authors consider this set of myocardial changes to be an initial phase of ICM that shows no clinical manifestation at all. As coronary atherosclerosis progresses, the already damaged myocardium is superimposed by the morphological changes caused by higher hypoxia at the whole organ level. Depending upon a combination of these changes, one or another form of CHD and progression of chronic CHD may prevail at a later time.

CONCLUSION

ICM is a broader concept than chronic heart failure and it is a basis for the pathogenesis and morphogenesis of CHD.

[Platelet link of homeostasis system at modeling of chronic stress situation]

Changes of thrombocyte morphological and functional status were investigated in rabbits (2,5-3 kg weight) by the emotional stress model that was reproduced through stimulation with irregular low-level electric current. Thrombocytes were purified from the venous blood with sequential centrifugation. Obtained material was investigated with electron microscope using luminous coloring agent acridine orange and syliconized glass. Glycosaminoglycans and Ca2+ noncompensated negative electric charge, the activity of ATP, alkaline phosphatase, adenylate cyclase and phosphodiesterase of cyclical nucleotides, monoamine oxidase were cytochemicaly revealed. Consequently morphological and functional equivalents of chronic stress destabilization effect on blood platelets were determined. Likewise membranotropic and receptor mediated mechanisms of this effect realization were analyzed.

[Structural and metabolic aspects of heterogenicity of the ventricular cardiac myocytes in coronary insufficiency]

The paper shows comparative analysis of structural-metabolic changes of the ventricular cardiac hystiocytes during transitional restriction of blood supply, which leads to relapsing myocardium hypoperfusion, ischemia and even to cardiac infarction. We have established that an increase of the myocardium arrhythmogenicity, damage of myocardium electrophysiological activity and coronary deficiency are caused by pathologically intensified structural-metabolic heterogeneity of cardiomyocites. The chronic ischemic heart disease is worsening the situation by gradual accumulation of the metastructure changes of heart's working cells. It is possible to connect adaptable hypertrophy of cardiomyocites with compensatory redistribution of loading among them, what is accompanied with the deep reorganization of their metabolism and metastructure under the influence of neurohumoral factors, inadequate transport-trophic maintenance of the function, nonequal edema and fibrosis of the interstitium. The data obtained describe the formation of "prereadiness" of the myocardium to the fatal rhythm disturbance determined by interconnected structural-metabolic changes. Each of these pathological changes separately doesn't induce an impairment of myocardium electric stability but represents a necessary part in origin and development of the pathological process.

[Morphofunctional aspects of cardioprotective effect of propranolol in modelling of chronic ischemic heart disease]

In experiments involving simulation of ischemic heart disease in adult rabbits, morphofunctional aspects were studied of cardioprotective action of propranolol on the contractile myocardium. With the aid of histological and histochemical, electron microscopic tests, the drug under consideration has been shown to be endowed with membrane-stabilizing properties, quite aside its receptor-mediated effects on Ca2+ metabolism known for. A decrease in its excessive ingress into the sarcoplasma comes, in its turn, to improve energy and plastic maintenance of the myocardial functions, to moderate a pathological reorganization and destructive changes in cardiomyocytes, thus promoting the contractile myocardium resistance to recurrent coronary crises.

[Effect of long term administration of finoptin on the morphofunctional state of working cells of the intact myocardium in modeling of chronic coronary insufficiency]

In accordance with the findings on the key role of the cardiomyocite electrolyte homeostasis abnormality in dysfunction and coronary insufficiency-related alterative changes in the contractile myocardium and positive results of correction of the above abnormalities with Ca2+ antagonists morphofunctional aspects were studied of cardioprotective action of finoptin in its course administration in experiments in rabbits. General histological techniques were used together with transmission electron microscopy and cytochemical tests. The drug under study has been shown to increase the cardiomyocite glyco-calyx Ca(2+)-depositing function and to diminish its quickly-exchanging fraction on a plasmolemma. The benefits derived from the aforesaid under conditions of recurring coronary insufficiency include membrane-stabilizing effect, optimization of the energy balance and plastic processes in cardiomyocytes, with their ability to adjust themselves to conditions of the simulated pathology enhanced.

[Ultrastructure and metabolism of cardiomyocytes under experimental stress]

Morphogenesis of adaptational, disadaptational, and alterative changes affected structure and function of all live-supporting systems (contractile elements, macroergic phosphate synthesis, intracellular regeneration, and electrolyte exchange control) was studied in cardiomyocytes under experimental chronic stress using ultrastructural and cytochemical methods.

[Changes in the vascular wall in a combination of hypercholesterolemia and posttraumatic regeneration of the endothelium]

Proceeding from our notions about proatherogenic properties of hypercholesterinemia and capability of injurious effects on the vascular wall to stimulate the process, sequelae were studied of a combined effect of the above factors on the endothelial monolayer of the aorta in an animal experiment (rabbits, n = 17). Used in the study were AgNO3 impregnation, electron microscopy, histochemistry, and morphometry. It has been ascertained that association of chronic hypercholesterinemia with local mechanical damage to the vascular endothelium tends to change its morphofunctional properties to a greater degree than in differentiated action of each of them promoting significantly the development of atherosclerosis in differentiated action of each of them.

[The characteristics of the morphofunctional restructuring of the aortic endothelium in food-related atherosclerosis and hyperadrenalinemia]

Morphofunctional reorganization was studied of endothelium during the stage of formation of alimentary atherosclerosis and in experimental hyperadrenalinemia using transmission electronic microscopy and histochemistry together with silver nitrate impregnation of aortal endothelial monolayer. Certain morphofunctional equivalents have been established for the vascular wall exposure to the above factors, indicative of their unequalability and possibility of potentiation under combination. In both cases, an interrelationship similar in character has been shown between intensity of the endothelial reciprocal response and its regional morphofunctional features.

[The effect of the morphofunctional state of the thrombocytes on the activation of destabilization processes in patients with acute forms of ischemic heart disease]

With the purpose of assessing the influence that platelet morphofunctional state may have on the degree of destabilization in patients with different forms of unstable angina we examined 198 patients using stress tests, Holter ECG monitoring, studying activation of thrombocytes with the aid of a luminescent-microscopy technique, and performing an analysis of aggregation. Important differences have been revealed in the studied parameters in those patients presenting with freshly detected and progressive stenocardia and with a developing, despite of the treatments administered, myocardial infarction, that might be caused by abnormal shifts in the thrombocyte intact/activated forms ratio.

[The transport-trophic support of myocardial function in the modelling of chronic ischemic heart disease]

Using a model of chronic ischemic heart disease (recurring coronary insufficiency against the background of chronic hypercholesterolemia), regularities were studied of the microcirculation rearrangements in the myocardium. Employed in the studies were methods of light optics, electron microscopy, injection, as was morphometry. All structural and functional links of the myocardial microcirculation system were put to study, such as resistive, metabolic and blood-drawing segments of the microhemocirculatory channel, intramyocardial tracts of lymph outflow, and interstitium as a direct carrier of the intratissue milieu, as well as subepicardial portion of the lymphatic network of the heart. There have been determined the morphofunctional equivalents and morphogenesis of those changes disorganizing the transport processes in the myocardium under the above type disorder, such as changes in microhaemodynamics, permeability of the histohematic barrier, lymph outflow, and intermediary exchange; there have also been analysed the pathogenetic interrelations thereof. The results obtained suggest that dysfunction of the myocardial system of microcirculation should have a part as a local tissue factor of pathogenesis of cardiac insufficiency in ischemic heart disease.

[The regional structural-metabolic characteristics of the vascular endothelium]

The authors studied structural and metabolic features of endothelium of greater vessels (aorta and vena cava posterior) of full-grown rabbits, making use of silver impregnation, transmission electronic microscopy and electronic-histochemical tests for non-compensated negative charges of glycocalyx, oxidoreductase, enzyms determining responsiveness of endotheliocytes in receptor-mediated influences (adenilcyclase and phosphodiesterase). Significant difference was established in respect of the average area of the endothelial stratum elements and total length of intercellular bounderies in the aorta zones with different permeability to Evans blue, as well as of the above measures for the studied arterial and venous portions of the vascular system; some of the regional features of glycocalix and endotheliocyte metabolism were disclosed.

[The structural-functional properties of the thrombocytes in patients with a history of a myocardial infarct]

Functional state and morphological features of platelets were studied in patients with ischemic heart disease 3-24 months following the primary infarction and reinfarction. The studies made pointed to considerable changes in the structure, metabolism and reactivity of platelets. Chronic exposure to irritant factors makes for the depletion and destabilization of blood plates, their adhesive properties and ability to store and catabolize biogenic amines being upset, the destructive changes of glycocalix having a most pronounced impact on the platelet reactivity. The structural and functional disturbances revealed in the thrombocyte homeostasis have been found to correlate with the clinical course of the illness.

[The energy allowance and calcium homeostasis of the cardiomyocytes in the early stages of myocardial ischemia]

Morphofunctional equivalents are described of adaptive and abnormal reconstitution of CMC in acute coronary failure, using methods of light-transmission optics in combination with those of electron microscopy. It has been established that the contractile myocardium cell compensatory hyperfunction is provided by mobilization of a maximum number of the CMC organelles. Documented for the first time cytochemically is a direct interrelation between the metabolic activity of oxidoreductases, ability of mitochondria to accumulate Ca2+, and the status of their membranes. Exhaustion of the CMC adaptive potential was found to be associated with inconsistencies between metabolic and Ca(2+)-binding capacity of mitochondria, sarcoplasmic reticulum (CPR), and sarcolemma, these causing desynchronization of myofibrils restricting the CMC contractile apparatus function. The above changes develop prior to the destruction of the organelle membranes, resolved with the routine electron microscopy. It has been shown that inhibition of ion-exchange functions of the basal and plasmic membranes involves redistribution of Ca2+ on these and is accompanied by a progressive impairment of the barrier properties of sarcolemmas.

[Role of hypercholesterolemia in the pathogenesis of atherosclerosis]

The pathogenic role of hypercholesterolemia in the development of atherosclerosis was determined by investigation of the vessel's wall structural and functional peculiarities in rabbits, which were kept on atherogenic diet. It was evident, that even short duration of hypercholesterolemia led to significant disturbances of vascular reactivity, which manifested mainly in the inhibition of endothelial vasomotor activity against a background of the initial increase of smooth muscle sensitivity to contracting influences. These changes were almost the same in quality and magnitude in all the investigated sections of the vascular system including venous. After the prolonged periods of hypercholesterolemia these changes became much more pronounced but remained well spread through the whole system. The data of the electron microscopy confirmed both predominant disturbances of endothelial structure and their generalized character under the influence of hypercholesterolemia. These results indicate that hypercholesterolemia itself cannot create all the features of vascular atherosclerotic damage and that unlipid factors must be considered as not less important in its pathogenesis.

[The basic patterns in the development of lymph circulatory failure in the heart]

63 adult rabbits were used to stimulate single physical exercise, acute and relapsing coronary insufficiency, alimentary atherosclerosis and to study adaptive and pathologic changes in the lymphatic channel (LC) of the heart. LC of the heart in animals with alimentary atherosclerosis after cholesterol exclusion from their diet was studied to determine reversibility of these changes. LC of the heart was injected by differently coloured masses and was investigated by the stereoangioscopic method on clarified preparations, on semithin sections and by the electron-microscopic method. Changes in different elements of a lymphatic net were of the stereotype character, as a whole. Morphofunctional reactions determining the development of the chronic insufficiency of the lymph flow in the heart form as successively following phases which change both due to exposition of the pathological process-initiated effect and due to certain endogenic factors arising during arrangement of LC of the heart.

[The morphological characteristics of the cardiac lymphatic bed in chronic coronary failure]

A study is presented of the morphological changes of the lymphatic circulation in chronic ischemic heart disease (IHD). Examinations were carried out on clinical material: intraoperative cardiac biopsies and on hearts of patients who died of this disease at the age of 36-59 years. Transmission electron microscopy was used. A clinical comparison was realized of changes of intramyocardial and subepicardial regions of the heart lymph circulation and morphological equivalents of disorders of outflow of lymph from the heart in chronic IHD were evaluated. The obtained data indicate the lymph stasis possessing cardiotoxic and sclerogenous properties is an essential pathogenetic factor of myocardial fibrotization in chronic coronary insufficiency.

[Various characteristics of the structure of the cardiac lymphatic bed and the morphofunctional basis of its insufficiency]

Structural peculiarities of the cardiac lymphatic bed have been studied, as well as its adaptive and pathological changes under physical load, acute and recurrent coronary insufficiency under conditions of mechanical blockade of the lymph outflow from the organ, which have been modelled in dogs and rabbits. The cardiac lymphatic bed is injected with various staining masses and investigated stereoangioscopically in translucent preparations, in semithin slices and electron microscopically. The rearrangement of lymphatic capillaries and vessels revealed is of stereotypical character. The degree of manifestation and correlation of morphofunctional reactions, characterizing development of insufficiency of the cardiac lymphatic vessels is mainly determined by intensity and exposition of pathological effects, exercised on it, while etiologic factors are of less importance.

[Structuro-functional features of different links in the microhemocirculatory bed of the myocardium]

Morphofunctional peculiarities of various elements of the microhemocirculatory bed (MHCB) of the myocardium performing correction of the nutritive blood stream, structures and mechanisms of the microvessel permeability have been studied. The investigation has been performed on 20 mature rabbits and 5 mongrel dogs, transmissive electron microscopy and certain cytochemical techniques applied for revealing ATP-ase, lactate-, malate-, succinate-dehydrogenases, cytochrome-C-reductase and glycosamine glycans. Structural differences in microvessels of various range are described. Together with smooth muscle cells in arterioles and precapillary sphincters, specialized endotheliocytes and valve-like formations, situating in the orifices of blood capillaries, participate in regulation of hemoperfusion of the MHCB functional units. The data have been obtained characterising cytolemma of the endotheliocytes as a complex system, where plasmolemma, being the bearer of ATP-ase and a complex of oxidoreductase, regulates physical-chemical properties of the paraplasmolemmal layer and ensures the control of all the forms of the transcapillary transport. Micropinocytic vesicles are proved to differentiate into two functionally asynonymous populations: one of them performs the energy-dependent transport, while the other reserves the plasmolemma.

[Spatial organization of the microcirculatory bed and organ-tissue functional elements of the myocardium]

Angioarchitectonics of the microhemocirculatory bed (MHCB) of the myocardium have been studied by means of injection techniques and an original method for elective revealing (silver impregnation). Hearts of healthy persons died accidental deaths, those of intact dogs and rabbits have been investigated. The MHCB structure of the left ventrical myocardium has been followed in details; certain peculiarities on distribution of microvessels have been revealed. They secure principally equal conditions for transport-trophic supply for all cardiomyocytes. The data obtained make it possible to outline a principle structural scheme for the organ-tissue functional elements of the myocardium.

[Ultrastructure of terminal myocardial arteries in chronic ischemic heart disease]

The ultrastructure of the terminal arteries and arterioles was studied on biopsy samples obtained during aortocoronary bypass surgery in ten patients with stenosing atherosclerosis of the major coronary arteries and a history of chronic CHD. A complex of morphofunctional shifts was identified affecting all layers of the vessel wall and leading to readjustment of every coat. The major cellular populations directly involved included endotheliocytes, smooth muscle cells and stromal cells. Fibroblastic elements, penetrating by their processes up to the subendothelial zone stimulated total fibrosis of the vessel wall. The changes detected are indicative of the impaired patency and alterations in the responsiveness of resistant vessels which can considerably affect the microcirculation and trophicity of tissue.

[Morpho-functional characteristics of the myocardium in extreme coronary insufficiency]

Morphogenesis of destructive and adaptational changes of the myocardial contractility were studied experimentally on dogs with limited bloodflow in the left coronary artery by 90% for 30 min. The light coronary methods and electron microscopy were used. The main ultrastructural variants of contractility disorders and cardiomyocyte damage are described, qualitative nonidentity of mechanisms in the ischaemic focus and in conditionally intact segments are recorded. It shows that irreversible structural shifts in the ischaemic zone of the myocardium develop along with the decrease of contractility, while in the intact areas this is preceded by intensive work of cardiomyocytes. At the base of adaptational reaction at the tissue level lies the formation of microfoci of functional hyperactivity and a relative rest.

[Cardiomyocyte ultrastructure in nonextreme coronary insufficiency]

The ultrastructure of the contractile myocardium taken from different zones of the left and right ventricles of the heart was studied during dosed restriction of blood flow in the circumflex branch of the left coronary artery by 30 and 50%. It was established that the changes of the cardiomyocytes in this situation are displayed by a combination of two differently directed processes, destructive-dystrophic and adaptational, the severity of which is determined by the intensity of the unfavourable effect. The whole parenchyma of the ventricles of the heart is involved in the reaction and there are no intact zones.

[Damage to the contractile myocardium in disorders of lymph drainage (experimental-morphologic findings)]

The role of the lymphatic system of the heart in the development of cardiosclerosis was studied in experiments in 43 adult dogs. An important influence of lymphogenic edema as an agent favouring the damaging of the myocardial parenchyma was established. Micronecroses occurring throughout the contractile myocardium stimulate a continuous substitution of the elements of the damaged parenchyma by the pre-existing or newly formed stroma. Proceeding from personal and literature data on the frequent involvement of the lymphatic system of the heart into its pathological processes it is suggested that the lymph directly participates in the development of the functional incompetence of the organ.