[An electron microscopic study of neocortex of Syrian hamsters (Mesocricetus auratus) infected with SARS-CoV-2 (Coronaviridae: Coronavirinae: Betacoronavirus: Sarbecovirus)].

INTRODUCTION: Convalescent COVID-19 patients have various signs of central nervous system damage, including those directly associated with SARS-CoV-2. Hence, studies of SARS-COV-2 related morphological changes in neocortex are particularly relevant for understanding the mechanisms of their formation and development of approaches to preclinical evaluation of the effectiveness of antiviral drugs. The purpose of the research is a longitudinal study of the ultrastructural alterations in Syrian hamsters neocortex after experimental SARS-CoV-2 infection. MATERIALS AND METHODS: Male Syrian hamsters weighing 80100 g, aged 4 to 6 weeks, were infected with 26 l SARS-CoV-2 intranasally with 4104 TCD50/ml of viral particles. The animals were euthanized on days 3, 7 or 28 post-infection, the brain was extracted with the cortex excision. The material analysis was performed using transmission electron microscopy. RESULTS AND DISCUSSION: On day 3 post-infection, the number of moderately hyperchromic neurons in neocortex increased, while by the day 7 the number of apoptotic cells significantly increased. Simultaneously, an increased signs of neuronophagy and representation of atypical glia were observed. Increased number of altered oligodendrocytes was observed on day 28 post-infection. Viral invasion was accompanied by changes in neocortical cells since day 3 post-infection, such as transformation of their nucleus, the rough endoplasmic reticulum and the Golgi vesicles as well as microvascular spasm with perivascular edema. CONCLUSION: As a result of electron microscopic study, the ultrastructural alterations in neocortex were described in an experimental model of SARS-CoV-2 infection. The findings can be used to identify the mechanisms of infection pathogenesis and to search for the new directions in development of medicines.

Evaluation of the Content of Aquaporin-5 and Epithelial Sodium Channel in the Lungs of Rats during the Development of Toxic Pulmonary Edema Caused by Intoxication with Acylating Pulmonotoxicants.

We studied the content of aquaporin-5 (AQP5) and epithelial sodium channel (ENaC) in rat lungs during the development of toxic pulmonary edema (TPE) caused by intoxication with phosgene and perfluoroisobutylene (1.5 LC50). The lung body weight index (LBI) was calculated and histological examination of the lung tissues was performed. Localization and expression of AQP5 and ENaC were determined by immunohistochemistry. Intoxication led to a significant (p<0.05) increase in LBI and histological changes typical of TPE 1 and 3 h after the exposure. In 1 and 3 h after phosgene intoxication, the AQP5 and ENaC content significantly (p<0.05) increased in comparison with the control. Similar changes in the AQP5 and ENaC content were observed 1 and 3 h after exposure to perfluoroisobutylene. It was hypothesized that AQP5 plays an important role in the formation of TPE caused by intoxication with acylating pulmonotoxicants. An increase in the content of ENaC can be considered as a compensatory reaction of the body aimed at clearance of the alveolar fluid.

[Specific features of the pathology of the respiratory system in SARS-CoV-2 (Coronaviridae: Coronavirinae: Betacoronavirus: Sarbecovirus) infected Syrian hamsters (Mesocricetus auratus)].

INTRODUCTION: Verification of histological changes in respiratory system using Syrian (golden) hamsters (Mesocricetus auratus) as experimental model is an important task for preclinical studies of drugs intended for prevention and treatment of the novel coronavirus infection COVID-19.The aim of this work was to study pathological changes of pulmonary tissue in SARS-CoV-2 (Coronaviridae: Coronavirinae: Betacoronavirus; Sarbecovirus) experimental infection in Syrian hamsters. MATERIAL AND METHODS: Male Syrian hamsters weighting 80-100 g were infected by intranasal administration of culture SARS-CoV-2 at dose 4 × 104 TCID50/ml (TCID is tissue culture infectious dose). Animals were euthanatized on 3, 7 and 14 days after infection, with gravimetric registration. The viral load in lungs was measured using the polymerase chain reaction (PCR). Right lung and trachea tissues were stained with hematoxylin-eosin and according to Mallory. RESULTS AND DISCUSSION: The highest viral replicative activity in lungs was determined 3 days after the infection. After 7 days, on a background of the decrease of the viral load in lungs, a pathologically significant increase of the organ's gravimetric parameters was observed. Within 3 to 14 days post-infection, the lung histologic pattern had been showing the development of inflammation with a succession of infiltrative-proliferative, edematousmacrophagal and fibroblastic changes. It was found that initial changes in respiratory epithelium can proceed without paranecrotic interstitial inflammation, while in the formation of multiple lung parenchyma lesions, damage to the epithelium of bronchioles and acinar ducts can be secondary. The appearance of epithelioid large-cell metaplastic epithelium, forming pseudoacinar structures, was noted as a pathomorphological feature specific to SARS-CoV-2 infection in Syrian hamsters. CONCLUSION: As a result of the study, the specific features of the pathology of the respiratory system in SARSCoV-2 infected Syrian hamsters were described. These findings are of practical importance as reference data that can be used for preclinical studies to assess the effectiveness of vaccines and potential drugs.

Ultrastructural Changes in the Air-Blood Barrier of Rats in Acute Intoxication with Furoplast Pyrolysis Products.

Rats were exposed to fluoroplast-4 pyrolysis products (sample weight 2.6 g, pyrolysis temperature 440-750°C, pyrolysis duration 4 min) containing perfluoroisobutylene over 15 min. Lung tissue samples for histological and electron microscopic examination were isolated in 3 and 30 min after intoxication and processed routinely. Histological examination revealed no structural changes in the lungs. In ultrathin sections of rat lungs, some changes in the structure of type I pneumocytes were detected in 3 min after the exposure: detachment of cytoplasmic processes and the appearance of transcytosis pores. These changes attested to impaired cell-cell interactions and their adhesion to the basement membrane, where structural disorganization and edema of the collagen matrix were observed. In 30 min following exposure, the signs of damage to type I pneumocytes became more pronounced. The increase in the equivalents of transcellular and paracellular permeability in the alveolar lining profile was observed. No changes in the pulmonary capillary endotheliocytes were detected, which suggest that type I pneumocytes are the primary target of the toxic effect of perfluoroisobutylene. The vulnerability of a particular cell population, in view of specific metabolism of these cells, can be the key to deciphering of the mechanisms of the toxic effect of pyrolysis products of fluorinated polymer materials.

Mechanisms of Pulmonary Toxicity of Perfluoro-n-Alkane Pyrolysis Products with Consideration of the Structural Features of the Blood-Air Barriers.

Perfluoroisobutylene a is pulmonotoxic chemical generated during pyrolysis of perfluoro-nalkanes (polytetrafluoroethylene). The mechanisms of acute pulmonary toxicity induced by perfluoroisobutylene have not been studied yet. The analysis of tissues of brown frogs showed that the products of polytetrafluoroethylene pyrolysis induce typical inflammatory response in the lungs (fluid accumulation, erythrocyte stasis, desquamation of the epithelium, and capillary plethora in lung septa) and oropharyngeal cavity (degeneration of ciliated epithelium, hyperemia of underlying vessels with plasmatic imbibition of the connective tissue, and margination of segmented leukocytes and monocytes). The absence of surfactant is a specific feature of the blood-air barrier of the oropharyngeal cavity in frogs compared to the lungs. It can be hypothesized that toxic effects of perfluoroisobutylene are determined by its influence on epithelial (pneumocytes and cells of nonkeratinized stratified ciliated epithelium) and endothelial cells. Even though the effects of the agent on surfactant cannot be excluded, they do not determine the probability of development of inflammatory response.

Use of nanotechnology in the creation of moden medicines-governmental funds and their targeting systems (literature review).

Properties of nanoscale carriers recommended by the European Pharmacopeia for use in the creation of drugs and their complexes with physiologically active substances are given. Ihe authors present general descriptions of the methods of creation and especially of carriers identified in the accumulation of experience in their use for creating drugs with desired properties of penetration of biological barriers and length of service of the therapeutic effect.

Changes in Respiratory Function during Treatment with Combination of Analgesic Substances Trimeperidine and Dexmedetomidine.

The effects of analgesic substances trimeperidine and dexmedetomidine and their combinations in different proportions (0.75:0.25, 0.5:0.5, 0.25:0.75 of the medium effective doses of each substance) on respiratory function was studied in experiments on rats. Administration of substances in 1 ED50 by analgesic effect (corresponded to medium therapeutic dose of trimeperidine in humans) was characterized by significantly longer suppression of respiration over 90 min in comparison with combined treatment with these substances. Administration of the substances in a dose of 8 ED50 by analgesic effect (corresponded to daily therapeutic dose) over 60 min was followed by more than 3-fold reduction in respiration frequency and respiratory minute volume, more pronounced in animals receiving trimeperidine. Combined administration of these drugs in the specifi ed dose induced less pronounced suppression of respiration and combined administration of trimeperidine and dexmedetomidine in proportion of 0.75:0.25 signifi cantly reduced the period of restoration of respiratory parameters in comparison with animals receiving single substances.

[On selection of external bleeding models for preclinical evaluation of the effectiveness of local haemostatic agents (literature review)].

On selection of external bleeding models for preclinical evaluation of the effectiveness of local haemostatic agents (literature review). To temporarily stop of external bleeding traditionally use a pressure bandage or tourniquet, but not for all types of wounds it is possible and appropriate to apply these dressings. In recent times there has been significant progress in the development and improvement of local haemostatic agents used for the first aid. There are currently conflicting information about their effectiveness, presented by various authors, requires standardization of experimental modelsforpre-clinical testing of medical devices in this class. Following a review of domestic and foreign literature DroDosed to standardize external bleeding model for assessing the effectiveness of local haemostatic agents.

[Lines of research in the field of cellular technologies and its application in military medicine].

The paper presents an overview of cellular therapy products and medical tissue engineering of the leading countries of the world (including the US) and identifies lines of research in the field of cellular technology application in the interests of national military medicine. The authors gave information concerning practical implementation of the achievements of biomedical research in the field of regenerative cellular products and technologies in Russia as different products, which may be used at the stages of medical evacuation. The authors presented results of research, which was, performed on the model of mine blast injury in accordance with principle possibility of the usage of cellular technologies products (multipotent mesenchymal stromal cells) in medical practice.

[The state research and test institute of military medicine of the Ministry of Defence of the Russian Federation celebrates the 85th anniversary].

The state research and test institute of military medicine of the Ministry of Defence of the Russian Federation celebrates the 85th anniversary. The article is devoted to the anniversary of the newly reconstituted state research and test institute of Military Medicine of the Ministry of Defence of the Russian Federation. The institute was closed down in 2011 and worked exclusively as a structural subdivision of the Kirov Military Medical Academy for tests of ergonomic characteristics of a weapon and military equipment. Recreation of the institute allowed to engage highly qualified personnel and change the range of tasks, identified prospects of fundamental and applied researches in the field of development of hemostatic agents and anaesthetics, physiology of military work, medical robotics, development of technical means for medical services, and development of new medical technologies. The authors formulated prospects of development of the institution and its participation in the implementation of the primary tasks of the Medical Service to preserve and improve the health of military personnel.

[Consequences learned from the use of chemical weapons during the First World War for the modern military medicine].

The article describes the way medical service dealed with problems resulted from the use of chemical weapons during the First World War (1914-1918). It was revealed that many of the abovementioned problems remain unsolved up to the present moment. It is stated the existence of the threat of use of chemical weapons in modem military conflicts, which expands the area of responsibility for medical chemical protection. The authors proved necessity and algorithm of the training system, considered as a part of medical protection in case of adverse factors of chemical nature.

[Pharmacological tolerance to medical therapy of organophosphate poisoning and ways of tolerance management].

Authors consider causes of low efficiency of antidote therapy and ways of pharmacological tolerance management during medical treatment of organophosphate poisoning. One of the promising ways is a preventive antidote on the base of enzyme agents and allosteric modulators of a cholinesterase activity. Authors showed a expediency of a study of new acetylcholinesterase reactivators, its compositions and ways of drug delivery. Authors specified ways of searching for anticonvulsants from classes of quick-closing benzodiatines and NMDA-antagonists. Authors defined ways of improvement of methods of special antidotes delivery with targeted transport system. Authors made an assumption about the necessity of symptomatic treatment.

Prospects of using benzodiazepines in complex therapy of poisonings with anticholinesterase agents.

The efficiency of benzodiazepines on mouse model of anticholinesterase poisoning was shown. The protective effects of clonazepam and midazolam were observed at high (1 TD50, incoordination) and medium (0.3 TD50) doses and the effects of phenazepam and diazepam were found only at high doses. Midazolam produced the most pronounced protective effect: administration of this drug significantly increased the protective index of atropine+HI-6 combination during poisoning.

[Application of robotic technology to the needs in the medical service of the Armed Forces].

Application of robotic technology to the needs in the medical service of the Armed Forces. Further development of the medical service is inseparably associated with the implementation of robot technology into the practice of medical support of the Armed Forces of the Russian federation. For this purpose it is necessary to create a clinical scientific research centre of robot technology and interdepartmental scientific research simulation training center on the basis of the Kirov Military Medical Academy. It is also necessary to provide development of medical robotic complexes of tactical level of the medical service.

[Specific features of the anticonvulsant effect of memantine in mice intoxicated with a model organic phosphate].

The effect of memantine administration has been studied on the model of mice poisoning with an anticholinesterase compound. It is established that the memantine action is due to its influence on the cholinesterase activity in the brain, blood plasma, and erythrocytes in addition to its NMDA-blocking action. Memantine promotes oxime-induced erythrocyte enzyme reactivation on the model of mice poisoning with anticholinesterase compound (0.8 LD50).

[Pharmacological activity of n-(1-phenethyl-4-piperidyl) propionanilide modified by encapsulation in PLGA nanoparticles].

Technological parameters for the effective encapsulation of n-(1-phenethyl-4-piperidyl)propionanilide in poly(lactid-co-glycolide) (PLG) nanoparticles have been determined. Depending on the ratio of drug fractions adsorbed on the particle surface and associated with the polymer matrix, n-(1-phenethyl-4-piperidyl)propionanilide (200 microg/kg, i/m) loaded PLG nanospheres accelerated time onset and increased duration of sleep in rats: by a factor of 1.6 - 2.0 for polymer associated drug fraction within 40 - 60% and by a factor of 2.2 - 2.6 for polymer associated drug fraction within 60 - 80%. A similar increase of sleep duration was observed when free n-(1-phenethyl-4-piperidyl)-propionanilide was administered at doses within 400 - 500 microg/kg.

[Role of Chlamydia trachomatis and Chlamydophila pneumoniae in damage of eye posterior segment structures].

AIM: Study the ability of Chlamydia trachomatis and Chlamydophila pneumoniae to damage structures of eye posterior segment, features of development of such infectious process, its morphological and clinical characteristics. MATERIALS AND METHODS: 6 rabbits with confirmed absence of C. trachomatis, C. pneumoniae were used in the study. 3 animals were infected with C. trachomatis culture and 3 animals--with C. pneumoniae culture. Subconjunctival and intravitreal mode of infectious agent introduction were used, as well as instillation of its culture into conjunctival sac. Microbiological diagnostics included microscopy with direct immunofluorescence, culture method and determination of antibody titers. Infectious process was studied by using ophthalmologic methods and histological examination. Observation period was 4 months. RESULTS: In all the animals a development of infectious process at early stages after the infection was confirmed. Conjunctivitis symptoms, inflammatory exudation into vitreous humor, chorioretinal inflammation loci, disorders in transparency of optical media and detachment of retina were clinical manifestations. In 2 animals infected with C. trachomatis severe panuveitis was noted. In 4 animals infectious process assumed subclinical characteristics (infection with both C. trachomatis or C. pneumoniae). In pathomorphologic studies data on the ability of C. trachomatis and C. pneumoniae to cause damage to cells of retina, pigment epithelium and choroid were obtained. CONCLUSION: C. trachomatis and C. pneumoniae may play a significant role in pathology of vitreous humor, retina, pigment epithelium and choroid.

A model of cerebral circulation disorders created by staged ligation of the common carotid arteries.

A model of brain ischemia induced by staged ligation of the left and right common carotid arteries has been developed in experiments on rats. The use to this model led to reduction of animal mortality. On days 2-5 after the second ligature, the animals lost weight, the level of their CNS vulnerability increased, the volume of perceived information reduced, adaptation to environmental conditions and reproduction of conditioned reflexes were disordered. Focal and diffuse destructive changes in the nerve and glia cells were found in the cerebral cortex, hippocampus, and thalamic nuclei. The severity of disorders in the blood supply to the brain depended on the interval between ligation of the carotid arteries. This recommends this model for evaluation of the efficiency of drugs of various pharmacological groups.

[Studying toxicity caused by interaction of caffeine and ketorolac].

Combined administration of caffeine and ketorolac (NSAID) is accompanied by all possible types of drug interaction. Side effects of the drug combination are mostly due to the action of ketorolac and manifested by decompensated renal failure and progressive endotoxemia within 3 - 7 days after single administration of drugs. Thus, the amplification of ketorolac effects by caffeine must be taken into consideration in prescribing NSAIDs.

[Antioxidant properties of some sulfur-containing substances].

The antioxidant properties of sulfur-containing substances have been experimentally studied in vitro. Unithiol exhibits a wide spectrum us radicals. For this reason, unithiol can be considered, along with ascorbic acid, as a universal drug for the reduction of free radical reactions.