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.

SARS-CoV-2 spike protein-mediated cell signaling in lung vascular cells

Currently, the world is suffering from the pandemic of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that uses angiotensin-converting enzyme 2 (ACE2) as a receptor to enter the host cells. So far, 30 million people have been infected with SARS-CoV-2, and nearly 1 million people have died because of COVID-19 worldwide, causing serious health, economical, and sociological problems. However, the mechanism of the effect of SARS-CoV-2 on human host cells has not been defined. The present study reports that the SARS-CoV-2 spike protein alone without the rest of the viral components is sufficient to elicit cell signaling in lung vascular cells. The treatment of human pulmonary artery smooth muscle cells or human pulmonary artery endothelial cells with recombinant SARS-CoV-2 spike protein S1 subunit (Val16 - Gln690) at 10 ng/ml (0.13 nM) caused an activation of MEK phosphorylation. The activation kinetics was transient with a peak at 10 min. The recombinant protein that contains only the ACE2 receptor-binding domain of SARS-CoV-2 spike protein S1 subunit (Arg319 - Phe541), on the other hand, did not cause this activation. Consistent with the activation of cell growth signaling in lung vascular cells by SARS-CoV-2 spike protein, pulmonary vascular walls were found to be thickened in COVID-19 patients. Thus, SARS-CoV-2 spike protein-mediated cell growth signaling may participate in adverse cardiovascular/pulmonary outcomes, and this mechanism may provide new therapeutic targets to combat COVID-19.

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.

[Quality of life in patients with chronic internal hemorrhoids treated with infrared photocoagulation]

The results of quality of life estimation in the patients are presented, in whom infrared photocoagulation was applied for chronic internal hemorrhoids, including in 141 (58%) of them--performed, according to the standard method (control group) and in 102 (42%)--according to the elaborated method of selective infrared photocoagulation of distal branches of a. rectalis superior under Doppler control (the group of investigation). The patients quality of life was estimated with the help of SF-32 questionnaire according to WHO protocol (WHOQOL, 1993) before the treatment and in 6 mo, 1 and 2 years after the miniinvasive treatment conduction. In the patients of investigation group all the quality of life indices were trustworthy better (P < 0,01), comparing with those before the treatment.

[Age-related characteristics of the role of the endothelium in the response of vascular smooth muscles to hormones. The role of ultrastructural changes]

The experiments performed on isolated preparations of femoral artery and aorta of the mature and old rats as well as on those of coronary arteries of adult and old subjects failed to reveal direct participation of endothelium in the realization of insulin and vasopressin effects on the smooth muscles of the vessels studied. However, the endothelium modulated their influence on the vessels in the mature age. The lack of modulating effect of the endothelium in old age may be a result of its structural changes and thickening of a hemato-cellular barrier of the vessel wall observed by electron microscopy.

[The age-related characteristics of the effect of vasopressin on the vascular smooth muscles of the human brain]

Vasopressin was shown to cause a concentration-dependent relaxation of human basilar [correction of bacillary] artery's smooth muscles. In old age, the reactivity of these muscles in decreased and tachyphylaxis to vasopressin disappeared. This seems to be connected with a decrease in the quantity of smooth muscle's V2-inhibitory receptors. Protein kinase C activation does not affect molecular mechanisms of vasopressin action on human basilar [correction of bacillary] artery's smooth muscles. The data obtained suggest vasopressin participation in regulation of human cerebral blood flow and a limitation of adaptive properties of brain vessels' smooth muscles in old age. These factors, apparently, play a role in development of the brain circulation pathology in old men.

[An experimental model of DIC syndrome]

Disseminated intravascular coagulation syndrome (DIC-syndrome) is experimentally reproduced by introduction of 30% aqueous solution "Desoxon-3" (2800-300 mg/kg) into the organism of laboratory animals (rabbits). The preparation was perorally introduced once on an empty stomach for 1 min. Biochemical and pathomorphological studies testify to the development of the typical DIC-syndrome in rabbits. It is concluded that the model suggested makes it possible to thoroughly study genesis, course, consequences of the development and preventive measures of disseminated intravascular blood coagulation, a complex pathological process.

[Analysis of ultrastructural myocardial changes in the pathogenesis of post-resuscitation circulatory insufficiency]

The article deals with the electron-microscopic characteristics of morphofunctional changes in the myocardium of dogs resuscitated by means of donor extracorporeal circulation after 13--15 minutes of clinical death caused by an electrical trauma. Damage to the energy and contractile apparatus of the myocytes and structures of the microcirculatory channel was revealed in different postresuscitation periods (in 1, 4--5, 9 hours and in 3 days). The revealed morphofunctional changes were marked by phases. Previous study of changes in the main parameters of hemodynamics in the same animals showed that the hemodynamic shifts occurred in phases; sharp hemodynamic disorders were determined 4 to 5 hours after life had been restored. The authors conclude that the damage to the intracardiac mechanisms responsible for the pump activity of the heart plays an essential role in the genesis of postresuscitation circulatory insufficiency.