Pathomorphological changes in pulmonary vessels at different terms of lethal outcomes of patients with COVID-19

Objective: to study the pathomorphological changes in the vessels of the lungs at different times of death in patients with COVID-19. Material and methods: autopsy protocols of 40 deaths from COVID-19 with histological, histochemical examination, and photoregistration. To determine the degree of pulmonary vascular lesions, the authors developed and applied a semi-quantitative assessment scale for the sign based on counting the affected lung vessels in 10 fields of view, expressed as a percentage: no sign – (0%), weak sign + (1-25%), moderate sign ++ (26-50%), expressed sign +++ (51-75%), highly expressed sign ++++ (76-100%). Results: during the first 14 days of the disease, stasis and swelling of individual endotheliocytes were noted in the vessels of the microvasculature. A›fter 15-21 days of the development of COVID-19, signs of alterations in endothelial cells and microthrombosis were observed in microvessels. A›fter 22-28 days of the disease, the phenomena of repair and hyperplasia of endothelial cells were detected. At different times of the development of the disease in the lung tissue, the phenomena of acute respiratory distress syndrome, interstitial pneumonia, and focal pneumofibrosis were observed. Conclusions: the authors believe that COVID-19 is associated with a progressive microvascular endotheliopathy in the lungs which is characterized by swelling, alteration, and later, by hyperplasia, and regeneration of endothelial cells in combination with microthrombosis. Destructive changes in the walls of the microvessels of the lungs have superficial character without the destruction of the reticular frame and basal membranes. Endotheliopathy, microthrombus formation of microvessels of the lungs, and interstitial pneumonia create a vicious circle of severe respiratory failure, which must be taken into account in the clinic to correct the treatment of patients with COVID-19.

Fibrin-Plasma Rich in Growth Factors Membrane for the Treatment of a Rabbit Alkali-Burn Lesion

The purpose of this work is to describe the use of Fibrin-Plasma Rich in Growth Factors (PRGF) membranes for the treatment of a rabbit alkali-burn lesion. For this purpose, an alkali-burn lesion was induced in 15 rabbits. A week later, clinical events were evaluated and rabbits were divided into five treatment groups: rabbits treated with medical treatment, with a fibrin-PRGF membrane cultured with autologous or heterologous rabbit Limbal Epithelial Progenitor Cells (LEPCs), with a fibrin-PRGF membrane in a Simple Limbal Epithelial Transplantation and with a fibrin-PRGF membrane without cultured LEPCs. After 40 days of follow-up, corneas were subjected to histochemical examination and immunostaining against corneal or conjunctival markers. Seven days after alkali-burn lesion, it was observed that rabbits showed opaque cornea, new blood vessels across the limbus penetrating the cornea and epithelial defects. At the end of the follow-up period, an improvement of the clinical parameters analyzed was observed in transplanted rabbits. However, only rabbits transplanted with cultured LEPCs were positive for corneal markers. Otherwise, rabbits in the other three groups showed positive staining against conjunctival markers. In conclusion, fibrin-PRGF membrane improved the chemically induced lesions. Nonetheless, only fibrin-PRGF membranes cultured with rabbit LEPCs were able to restore the corneal surface.

INVESTIGATION OF EMBRYONIC HISTOGENESIS OF THE PAROTID GLAND

Lectinohistochemistry methods are very sensitive and allow to identify certain types and subpopulations of cells, to characterize non-cellular tissue structures in morphological studies, when they cannot be differentiated by using traditional methods of carbohydrate histochemistry. In many diseases, changes in the carbohydrate component of various glycoconjugates are observed, which contribute to the modification of morphofunctional characteristics of the cell and changes in its interaction with other cells and extracellular factors. Most studies are devoted to the study of the existing pathology of individual organs and systems (or their norms) in adults and animals. Data from the scientific literature on the histotopography of lectin receptors in the first months of human prenatal ontogenesis are few, and regarding the peculiarities of the expression of carbohydrate determinants of the rudiments of the human parotid gland in early prenatal ontogenesis - are absent. Glycopolymers compounds make up structural and functional basis of cells and tissues of a living organism. The necessity of anatomical-lectinohistochemical examination of the parotid gland in early prenatal period of ontogenesis is substantiated, as the evidences concerning its topography are fragmentary and unsystematized, and certain aspects of its ontogenesis are disputable. A natural redistribution of glycopolimers of the cytolemma and cytoplasm of the cells of the epithelial anlage of the parotid salivary gland and the mesenchyma adjacent to it in the course of investigating 50 human embryos and prefetuses aged up 21 days to 12 weeks at stages 9-23 and the beginning of the fetal period according to the classification of Carnegy’s institute has been revealed. Invagination of epithelial cells in the regions bucco-alveolar pockets into the underlying mesenchyme and their transformation into epithelial cords due to the accumulation of specific glycopolymers lectin WGA, SNA, HPA, RCA, LABA. The results of lectin-histochemical examination of the early prenatal ontogenesis of the parotid gland can form the basis for the work of laboratories dealing with screening of morphological material in order to assess the degree of maturation and prognosis of fetus viability and diagnostics of deviations from normal development.

Hydrallantois in cows naturally poisoned by Sida carpinifolia in Brazil

Sida carpinifolia is a small subshrub that is distributed throughout Brazil and is responsible for lysosomal storage disease and occasional reproductive problems in cattle, goats, equids, sheep, and deer. We describe herein the clinical, epidemiologic, and pathologic features of hydrallantois in 3 cows naturally poisoned by S. carpinifolia in Rio Grande do Sul State, Brazil. Clinically, all cows had marked abdominal distension and mild ataxia. After natural death or euthanasia, autopsies revealed that the abdominal distension in all 3 cases was caused by severe enlargement of the uterus, which contained 100–120 L of translucent fluid within the allantois, in addition to adventitial placentation. Microscopic evaluation of the placenta revealed marked diffuse edema, sometimes with a myxomatous appearance. Neurons in the cerebellum and obex were swollen, with mild-to-moderate cytoplasmic granular vacuolation. Histochemical examination with lectins ConA, WGA, and sWGA revealed mild-to-marked staining in the cytoplasm of neurons of the cerebellum and medulla at the level of the obex, indicating the occurrence of α-mannosidosis.

LECTIN-HISTOCHEMICAL REGULARITIES OF DIFFERENTIATION OF THE HUMAN PAROTID GLAND EPITHELIAL GERMS

Glycopolymer compounds make up structural and functional basis of cells and tissues of a living organism. The necessity of anatomical-lectinohistochemical examination of the parotid gland in early prenatal period of ontogenesis is substantiated, as the evidences concerning its topography are fragmentary and not systematized, and certain aspects of its ontogenesis are disputable. 35 human embryos and pre-fetuses aged from 21 days to 12 weeks of intrauterine development were examined. Glycopolymers were found by means of treatment of serial sections with lectins conjugated with horseradish peroxidase. The dynamics of prenatal morphogenesis of the embryos and pre-fetuses of the 4th-12th week of embryogenesis expression of glycopolymers – lectinreceptors on the surface of cells, in the cytoplasm and on the basal membrane of the parotid gland epithelial germs and the human oral cavity with its derivatives by re-distribution of glycopolymers are similar, which can be the evidence of ectodermal source of the parotid gland epithelial germ. Immersion of the epithelial cells of the buccal-alveolar pockets into the lower adjacent mesenchyme with the formation of primary parotid gland germs in embryos with 11,0-12,5 mm of PCL and their transformation into the epithelial taeniae is associated with accumulation of sialic glycopolymers (N-acetyl neuraminic acid), N-acetyl-D-glucosamine – specific to Wheat germ agglutinin (WGA) and Sambucus nigra agglutinin (SNA); N-acetyl-2-desoxy-2-amino-D-glucopyranose, screened by sialic acid of ß-D-galactose and α-L-fucose – specific to Helix pomatia (edible snail) agglutinin (HPA), Rhizoctonia solani agglutinin (RCA) and Laburnum anagyroides (Golden Rain shrub) agglutinin (LABA) respectively. These glycopolymers are present during the first 12 weeks both on the cytolemma of the cells of the parotid gland epithelial germ and in their cytoplasm. The results of lectin-histochemical examination of the early prenatal ontogenesis of the parotid gland can form the basis for the work of laboratories dealing with screening of morphological material in order to assess the degree of maturation and prognosis of fetus viability and diagnostics of deviations from normal development.