The immune system plays a crucial role in maintaining the body's homeostasis, determining the state of health of animals and their ability to adapt. The work aimed to investigate the effect of a feed additive based on milk thistle fruits, selenium, metiphene, and vitamins A, E, and C on rats' immune status under experimental tetrachloromethane poisoning conditions. The study was conducted on young white male Wistar laboratory rats. Intragastric administration of tetrachloromethane twice (with an interval of 48 hours) in a dose of 0.1 ml per 100 g of body weight in a 50 % oil solution was used for the experimental intoxication of rats. The animals of the second experimental group were fed the feed additive “Sylimevit” for 30 days together with feed at a dose of 0.1 g per 100 g of body weight. The introduction of tetrachloromethane in experimental groups of rats led to the development of oxidative stress, which occurs due to specific chemical processes in the body of experimental animals. It was found that the development of oxidative stress caused by tetrachloromethane leads to suppression of the humoral and nonspecific link of the immune system of rats. This is manifested in a decrease in the bactericidal and lysozyme activity of the blood serum, a decrease in the phagocytic index, and the phagocytic activity of neutrophils. In addition, an increase in the number of circulating immune complexes was observed. It was also established that feeding the feed additive “Sylimevit” strengthens the immune defense of the body of rats poisoned with tetrachloromethane. This feed additive helps to strengthen the body's defense mechanisms, increasing
the immune response and helping to resist the toxic effects of tetrachloromethane.

Introduction. The doxorubicin model was used for research, which, according to many authors, most adequately reproduces heart failure of varying degrees of severity. Doxorubicin is an antibiotic that has a cytostatic effect. The mechanism of its action consists of interaction with DNA, formation of free radicals, and inhibition of nucleic acid synthesis. The doxorubicin action and the development of hypoxia are accompanied by the activation of oxidative stress, the strengthening of free radical processes, and changes in the metabolism of carbohydrates, proteins, and lipids.
The aim of the study – the effect of the drug “Bendamine” on the indicators of antioxidant protection of the body of rats under experimental simulation of heart failure.
Research Methods. Modeling of heart failure was performed on sexually mature male Wistar rats with a body weight of 180–200 g. In blood and myocardial homogenate, the level of lipid peroxidation products, the activity of antioxidant enzymes, and the level of reduced glutathione were determined against the background of doxorubicin intoxication and when using the drug “Bendamine”.
Results and Discussion. During doxorubicin intoxication, LPO processes are enhanced in rats, which is indicated by the increased lipid hydroperoxides, diene conjugates, and TBA-active products in the blood and the homogenate of the rat myocardium of the first experimental group. It is worth noting that the inhibition of the antioxidant defense system was also established in intoxicated rats, as indicated by the low level of both enzymatic and nonenzymatic links of the antioxidant system. It was established that bendamine has a corrective effect on rats' oxidative stress conditions inherent in doxorubicin-induced heart failure. The drug “Bendamine” inhibits the excessive formation of POL products in pathologically changed tissues of the heart of rats and has an inducing effect on the system of antioxidant protection.
Conclusions. The influence of the drug "Bendamine" on the indicators of antioxidant protection of the body of rats under experimental simulation of heart failure was studied. Its antioxidant properties have been proven.

The properties of the spin-valve structure, based on two ferromagnetic layers divided by a layer of non-magnetic metal, in the geometry of the current perpendicular to the plane are modeled. In addition to well-known classical twochannel conductivity model proposed by Nevill Mott, the developed model takes into account spin scattering on the surface between structures. The developed model uses equivalent electrical circuits to simulate a spin valve with parallel and antiparallel alignment. On the basis of this model, the dependences of the giant magnetic resistance on two geometric parameters of the structure—the ratio between the thickness of the free and the thickness of the fixed layers, and their ratio to the length of spin diffusion—are derived. Based on the developed model, numerical data are obtained for the spin valve, where the ferromagnetic layers are made of cobalt, permalloy, iron, and nickel. The portion of surface scattering in the giant magnetic resistance is also investigated. A general conclusion is made about the slight increase of the giant magnetic resistance due to the influence of surface scattering for structures based on cobalt, permalloy, and iron, but not for nickel. This outlines the scope of applicability of the developed model. 

In the pathogenesis of acute widespread peritonitis and accompanying diabetes, a vital link is an endogenous intoxication caused by the translocation of microorganisms and their toxins from the intestine into the blood, metabolic changes, and immunological reactivity of the body. Our work aimed to investigate the microbial composition in the parietal intestinal biotope and the features of the blood cytokine profile in animals with acute disseminated peritonitis on the background of streptozotocininduced diabetes. The study was conducted on 56 sexually mature non-linear white male rats. Diabetes mellitus was modeled by a single intraperitoneal injection of streptozotocin (60 mg/kg). On the 14th day of the development of streptozotocin-induced diabetes mellitus, a 10% filtered fecal suspension (0.5 mL) was injected into the abdominal cavity of animals, and acute generalized peritonitis was initiated. Sowing on nutrient media was carried out for bacteriological research to isolate a pure culture of microorganisms and their identification. The concentration of TNF-α, IL-1β, and IL-6 was studied by solid-phase enzyme immunoassay.
The research results demonstrate an imbalance of cytokines in the dynamics of experimental acute disseminated peritonitis against the background of diabetes and quantitative and qualitative changes in the microbiota of the parietal intestinal biotope. A decrease in the number of Escherichia coli strains isolated in monoculture and an increase in the number of twocomponent and three-component microbial associations were revealed, among which Enterobacter aerogenes, Escherichia coli, Bacteroides spp., Proteus mirabilis, Klebsiella spp. and Candida species prevailed.

Modern aspects of the pathogenesis of acute inflammation of the peritoneum that is concurrent with diabetes involves analysis of metabolic mechanisms, in particular peroxidaton of proteins – antioxidant defense. Therefore, the objective of our study was to examine the interrelation between the processes of free-radical oxidation of proteins and antioxidant system in the dynamics of development of acute generalized peritonitis against the background of streptozotocin-induced diabetes. The study was performed on 56 non-linear white mature male rats. Diabetes mellitus was modeled by a single intraperitoneal injection of streptozotocin (60 mg/kg). On the 14th day of the development of streptozotocin-induced diabetes, we injected 10% filtrated faeces suspension (0.5 mL) into the abdominal cavity, thus initiating acute generalized peritonitis. Oxidative modification of proteins in blood serum was studied using the I. F. Meshchyshen’s method and the condition of antioxidant protection was monitored according to the activities of superoxide dismutase, catalase, content of reduced glutathione, and the level of ceruloplasmin.
The study of the parameters of free-radical oxidation of proteins and study of the condition of antioxidant system in
blood of the rats with experimental acute generalized peritonitis against the background of streptozotocin-induced diabetes demonstrated that oxidative protein modification grew, while the parameters of the activity of antioxidant system were being inhibited, depending on the stage of acute inflammation of the peritoneum. We determined inverse correlation relationships between the products of free-radical oxidation of proteins and parameters of antioxidant system on the third and on the seventh days of modelling of combined pathology. Manifestation of acute generalized peritonitis concurring with streptozotocin-induced diabetes was accompanied by a gradual accumulation of the products of free-radical oxidation of proteins and exhaustion of the antioxidant defense during all stages of the development of acute inflammation of the peritoneum, peaking on the seventh day after administration of faecal suspension (terminal stage of peritonitis). The observed inverse correlations between the levels of oxidative modification of proteins and the activity of superoxide dismutase, catalase, reduced glutathione, and ceruloplasmin on
the third and on the seventh days of modelling of combined pathology indicate a predictive role of the processes of free-radical oxidation of proteins in exhaustion of antioxidant-defense resources.