Then based on the spatial mobilized plane (SMP) criterion and the Lemaitre strain equivalence hypothesis, this research develops a constitutive model considering rock chemical corrosion-water-confining pressure damage. The proposed damage constitutive model employs the extremum method to ascertain the two Weibull distribution parameters (m and F0) by theoretical derivation and exhibits satisfactory conformity between the theoretical and experimental curves. The damage constitutive model can be consistent in the stress–strain characteristics of the rock triaxial compression process, which verifies the rationality and reliability of the model parameters. The model effectively represents the mechanical properties and damage characteristics of rocks when subjected to the combined influence of water chemistry and confinement. The presented model contributes to a better understanding of tangible rock-engineered structures subjected to chemical corrosion in underwater environments.Aiming at the problem of chemical-mechanics-hydro (C-M-H) action encountered by rocks in underground engineering, chemical damage variables, water damage variables, and force damage variables are introduced to define the degree of degradation of rock materials. Stone is selected as the sample for acid corrosion treatment at  The Sichuan–Tibet Railway is a crucial long-term initiative in China, bringing a substantial impact on the economic growth of the Southwest region. The Sichuan–Tibet Railway traverses the areas affected by acid rain and cold climate from the eastern to the western regions , charactpH affects the permeability of fractured rocks. The suggested model is used to predict the long-term permeability evolution of a naturally occurring granite barrier within a geological repository under underground circumstances. For stress-assisted corrosion, a brand-new mechano-chemical coupled peridynamic model is presented. According to the model, nonlocal dilatation of the material close to the corrosion front determines the activation-controlled anodic dissolution [The integration of a constitutive model holds utmost importance in the framework of rock mechanics’ strength theory. Significant progress and achievements have been made in the theory of rock damage by researchers both domestically and internationally ,13,14,15solution . Sun et solution  defined solution  for rocksolution  used feesolution  providedpH value and duration. (3) The efficacy of strain-based damage constitutive models is limited due to the inadequacy of axial strain in accurately representing the strength of rock microelements [In summary, there have been significant advances in the field of rock constitutive modeling, but there are still limitations: (1) Insufficient research has been performed on the constitutive models of rock damage when conducting the bonding influence of chemical corrosion, water, and confining pressure. Furthermore, a significant portion of the extant literature on the strength criteria of rock microelements has opted to employ the maximum tensile strain criterion  and the elements . Moreoveelements . The Mohelements . (4) TrapH value and time, water damage variables, and mechanical damage variables based on Weibull distribution. These variables aim to accurately reflect rock materials’ mechanical properties and deformation characteristics in acidic and water environments, building upon prior research. The mechanism of continuous damage mechanics is utilized. A constitutive model for rock chemical corrosion-water-confining pressure coupling damage was developed, utilizing the SMP criterion as the rock strength criterion and relying on the Lemaitre strain equivalence hypothesis. Subsequently, the model was subjected to validation through a comparative analysis with experimental curves, indicating a satisfactory conformity level. The present study elucidates the damage mechanism and damage mechanism of rocks that have undergone acid erosion under the influence of both water and confinement pressure.Additional investigation is necessary in light of the aforementioned issues. This article presents chemical damage variables incorporating The rock specimen used for mechanism analysis of the HMC coupled rock dissolution and fracturing processes is shown in Chemical solutions seep into the rock through the interior pores of sandstones when they are exposed to a water–chemical environment. This occurs in the soluble mineral components and the solution of a specific ion chemical reaction ,33, for When sandstone is in an acidic chemical solution, a number of intricate physicochemical reactions take place that primarily result in the cement dissolving in the rock, changing the pore structure, weakening the intergranular connections, and degrading the mechanical properties. According to Mangold, D.C.  and otheStep 1: ion solute migration from a chemical solution to the water–rock contact;Step 2: at the water–rock contact, the initial interactions of ions with rock mineral components;Step 3: chemical reaction at the water–rock interface between ions in the solution and soluble minerals;Step 4: the product ions separate from the interface between water and rock;Step 5: the ions generated by the chemical reaction diffuse and migrate out of the rock body.In conclusion, the internal rock of calcareous cemented sandstone in an acidic chemical environment is the primary cause of mechanical damage. The chemical reaction between the cement and the hydrogen ions in the solution is the primary source of the mechanical damage since it results in cement loss through dissolving and weakens the bond between the particles. As time goes on, the cement is continuously dissolved. And because cement erodes over time, we can determine how much damage has been done to its mechanical characteristics and deformation characteristics by looking at how much of the soluble phase cement has been dissolved. Therefore, the degree of dissolving of the solubility can be used to analyze the degree of damage to its mechanical properties and deformation characteristics.In practical applications, chemical corrosion may cause damage to the bonding materials and affect their load-bearing capacity, which is usually referred to as damage modulus. According to the study in the literature , the damAccording to the available experimental evidence , the priim, in, ip, and iq are the balancing coefficients of the chemical equation, iA and +H are reactants, and iB and iC are products.The substances in the mineral composition of the rock react with the acid with the general chemical equation:pH and +H concentration,Based on the relationship between + concentration before and following an acid-base reaction, as well as the correlation between the chemical Equation (2) and the reactant composition, without taking into account the sequence of chemical reactions. The principle that the quantity of protons in a chemical reaction is equivalent to the charge can be applied to transform the mass proportion of reactants into the mass proportion of H+ to determine the quantity of soluble substances in moles.The determination of the number of soluble substances lost in a chemical reaction can be achieved by analyzing the alterations in Ht and initial time, respectively, i in all reactants that can react with +H, In the equation, pH value and time t can be obtained, and its expression is as follows:Combining Equations (1), (3) and (4), the chemical damage factor considering the initial Di present in rocks when it is in a solution. The underlying assumption of the reaction is that water is abundant, thereby facilitating a rapid completion of the reaction and rendering the impact of time negligible. During the progression of the chemical reaction, a specific quantity of soluble compounds will undergo dissolution and subsequently react with water, leading to the formation of a sequence of ions and molecules that will manifest within the resultant solution. Thus, the molar quantity of the dissolved concretion that has been lost can be determined by computing the molar quantities of both the reactants and the products involved.Mi represent the mass of the dissolved concretion iD and the molar mass of iD, respectively.Water has the potential to engage in a chemical reaction with N number of related substances The presence of a significant number of randomly distributed pores within rocks is attributed to their heterogeneity. Consequently, when subjected to external loads, the deterioration mechanism of rocks typically encompasses the initiation, progression, and aggregation of voids, which exhibit a strong correlation with the number of impaired microconstituents. In general, the deficiency of microelements in rocks exhibits a degree of stochasticity.N in the initial state, reflecting the degree of damage of rocks under the stress level Q.To better describe the damage changes of rocks at different stress levels, this paper defines the damage variable P) of microelement failure. If the probability density function of microelement failure is represented as P is the cumulative distribution function of F:Under external loads, the failure of rock microelements usually exhibits randomness. The Krajcinovic model shows that the damage variable of rocks can be defined as the probability ϕ(F)=Based on Equation (8), the damage variable of rocks under loading can be obtained as follows:V0, V1, and V2, respectively. The effective volume of rock under chemical corrosion–water damage and force coupling is V3. The ratio of defect volume to total volume is used to represent damage, that is, the ratio of defect volume to total volume.The combined effects of chemical corrosion and loading result in varied damage characteristics in rocks. Therefore, in cases where chemical corrosion, water damage, and confining pressure coexist, the aggregate extent of rock deterioration cannot be regarded as a mere summation of the individual damages. In this study, it is assumed that the undamaged rock, the rock that has undergone chemical corrosion damage, and the rock that has undergone chemical corrosion–load coupling damage correspond to effective volumes The overall damage variable of rocks under the coupling effects of chemical corrosion, water, and confining pressure can be determined by combining Equations (11) and (12):By substituting Equations (5), (6) and (10) into Equation (14), the overall damage variable of rocks can be determined under the combined influence of chemical corrosion, water, and confining pressure.I1, I2, and I3 are the first invariant of the stress tensor, the second invariant of the stress tensor, and the third invariant of the stress tensor, φ is the angle of internal friction of the rock, and K1 is the material constant.The SMP criterion proposed by Matsuoka and Nakai  in 1974,φ materials. Matsuoka et al. [The above formulation of the SMP criterion is only applicable to frictional materials but not to c-a et al.  extendedThe modified SMP guideline expression is:By combining Equations (18) and (19) and based on the associated flow rule, the expression for the SMP criterion of viscous materials can be obtained as:F is obtained as:Based on Equation (20), the SMP criterion-based microelement strength According to the generalized Hooke’s law and the principle of train equivalence, F of rocks under confining pressure based on the SMP criterion, that is:By combining Equation (22) and substituting effective stress with nominal stress in Equation (21), we can obtain the elemental strength By substituting Equations (5), (6) and (23) into Equation (15), the damage evolution equation of rocks under the coupling effects of chemical corrosion and load can be obtained, which is:En is the modulus of elasticity of the rock at pH n; v is the Poisson’s ratio and According to Lemaitre’s strain equivalence principle and the concept of effective stress, the strain observed in a damaged rock under nominal stress is equivalent to the effective strain exhibited by an undamaged rock under effective stress . The establishment of the constitutive relationship of rock damage can be achieved through the following means: According to the deformation coordination condition, it is obtained thatFrom Equations (25)–(27), a rock damage constitutive relationship is obtainedIn accordance with the experimental principle of the rock triaxial compression test, the confining pressure load is first applied during the test, and then the axial load is applied after the confining pressure stabilizes to the predetermined value. Therefore, before the axial load is applied, the rock will experience initial axial strain under the action of confining pressure. The recorded axial strain is the difference between the axial stress and the confining pressure The initial axial strain of rock under the action of confining pressure is:Since the test results do not include the initial axial strain generated before the axial pressure is applied, the actual axial strain The rock chemical corrosion-water-confining pressure coupling damage constitutive model can be obtained by substituting Equations (24) and (29)–(31) into Equation (28).m, and F0, that are necessary for the rock damage constitutive model proposed herein. The said parameters are determined based on the peak point  with Equation (32) yieldsSCF in Equation (39) is the F corresponding to the extreme value point of the stress–strain curve.Taking the partial derivative of Equation (32), we obtain:From Equation (36), it is known that:Taking the partial derivative of Equation (39), we obtain:Substituting Equation (42) into Equation (41), we obtain:m and F0:Combining Equation (37), we can obtain expressions for the parameters m and F0 into Equation (32), we can obtain the damage constitutive model of rock under the coupling effect of chemical corrosion-water-confining pressure.By using the parameter determination method described above and substituting the obtained parameters pH levels. The solutions were characterized by pH values of 3, 4, and 7, while a control group remained untreated. pH.The fundamental aspects of rock damage resulting from acidic solution corrosion are characterized by the degradation of the rock’s particle framework and the concomitant augmentation of its porosity. To ascertain the rationality and precision of the model, the present study references the findings of Wang . Blocks cD can be obtained by combining the mineral composition and Equation (5) of the sandstone.The chemical damage factor 2, Al2O3, and Fe2O3. The maximum and minimum values of the same component differ significantly, and their average was taken. Among them, the SiO2 content of sandstone was the highest with an average value of 51.2%; the average content of Al2O3 is 4.6%; the average content of Fe2O3 is 4.6%; the average content of MgO is 3.5%; the total content of the unstable components Na2O, K2O, and CaO is 3.4–15.0%, although the content is small but active in nature.The results of the chemical composition analysis of sandstone see  show tha2 is insoluble in water and difficult to react with acidic solutions. Existing data have shown that the dissolution of KAlSi3O8 and NaAlSi3O8 in feldspar at room temperature in acidic solutions is very small and can be ignored. Therefore, feldspar is considered an insoluble matrix. The soluble cementing materials that react with acids are mainly Fe2O3, MgO, and Al2O3 in the sandstone. The chemical reaction equation between clay minerals in sandstone and acidic solutions mainly includes:In (1)Sandstone reacts with acid in the following main ways:(2)Sandstone reacts with water in the following main way:2+, Na+, Mg2+, K+, and other cations. Under the influence of acid corrosion, the interior mineral components of sandstone dissolve and precipitate as ions.It is clear from the aforementioned reactions that the sandstone minerals were chemically interacted with water and acidic solutions to form Ca2+ dissolution. Since sodium feldspar predominates in the mineral composition of the rock sample and the dissolution rate of Ca2+ increases rapidly in the early stages of immersion, Ca2+ has the biggest dissolving rate of the four cations, followed by Na+. Of the four cations, Ca2+ dissolves the fastest, followed by Na+, and K+ and Mg2+ are primarily found in clay minerals such illite, muscovite, and montmorillonite. Illite, muscovite, montmorillonite, and other clay minerals are the principal sources of K+ and Mg2+ due to the low amount of K+ and Mg2+ produced and precipitated after acid exposure.The sandstone minerals’ calcite and calcium feldspar are incredibly fragile in the presence of acid, which increases the rate of CaThe fundamental premise of the reaction is that water is abundant, allowing for a quick completion of the reaction and insignificant effects of time. A certain number of soluble compounds will dissolve as the chemical reaction progresses, and when they do, they will react with water to generate a series of ions and molecules that will appear in the solution that results. Thus, by calculating the molar quantities of both the reactants and the products involved, it is possible to establish the molar quantity of the dissolved concretion that has been lost.pH level of the immersion solution has a direct impact on how much each cation dissolves. The chemical reaction between H+ and the minerals in the rock samples is stronger at lower pH values, and thus increases the pace at which the ions contained in the minerals dissolve. The chemical interaction between calcite (CaCO3) and strong acids is fairly simple to carry out and results in the formation of Ca2+ compounds, which then dissolve in the solution. The maximum rate of Ca2+ dissolution occurs in the solution; in an acidic environment, clay minerals such as montmorillonite, illite, and others dissolve, hydrolyze, and exchange ions. Acidic environments cause clay minerals such as montmorillonite, illite, and others to dissolve, hydrolyze, and exchange ions.The Dc using Equation (5), the soaking time t in Equation (5) should be selected as 70 h when the pH reaches preliminary stability rather than the entire soaking time of 200 h. After statistics, the number of moles of soluble cementing materials damaged by the red sandstone soaked in 1 L of chemical solution with an initial pH of 3 and reacted with H+ was found to be 3.8280 × 10−4 mol, and Dc(PH = 3) = pH of 4 and reacted with H+ was Dc(PH = 4) = pH of 7 and reacted with H+ was 0, and the number of moles of soluble cementing materials damaged by reacting with water was 0.625 mol, and Dw = 0.3144.Based on the mineral composition of sandstone in m and F0 under different pH values and confining pressures, as shown in Substituting the data from Compare the experimental curves under different hydrochemistry corrosion and different confining pressures with the constitutive model’s theoretical curve, as shown in m and F0 of the damage constitutive model based on the SMP strength criterion. Many scholars [m may be related to the strength of rock microelements, while parameter F0 represents the macroscopic average strength of rock. The parameters m and F0 under the SMP criterion are still closely linked to the strength of rock microelements and the macroscopic average strength of rock. F0 and m. However, the change of F0 and m has no effect on the linear deformation curve before the peak value. The effect of F0 and m on the nonlinear deformation part of the stress–strain curve of rock, especially the curve after the peak value, is significant and can change the shape of the curve.The analysis of 13 groups of data showed that there is a certain rule in the parameters scholars ,42,43 bem and F0) trends with changes in different values of pH and confining pressures. As can be seen in m shows an overall increasing trend with decreasing pH value. This means that the larger the value of m, the greater the degree of corrosion difference of the rock body in the region. With increasing confining pressure, the parameter m initially increases and then decreases, with a turning point appearing at the confining pressure of 4 MPa, showing a non-linear relationship with confining pressure. The parameter m essentially ceases to decrease during the course of the confining pressure from 6 MPa to 10 MPa. At pH = 7, a special case occurs where the parameter m decreases and then increases, m reflects the degree of dispersion of the data, which is caused by many factors such as measurement errors, errors due to fluctuating conditions, and regional differences in rock corrosion. In F0 represents the peak of the curve (maximum probability) when the corrosivity is related to the mean value of all corrosion samples but not equal to the sample mean. With increasing confining pressure, at pH = 3 and water, the parameter F0 initially decreases and then increases, and the turning point occurs at a confining pressure of 4 MPa. At pH = 4 and pH = 7, the parameter F0 increases and then decreases, and the turning point also occurs at 4 MPa. The parameter F0 continues to drop more sharply during the course of the confining pressure from 6 MPa to 10 MPa. When m is unchanged, as F0 increases rock peak strength increases, F0 reflects the size of macro average strength of rock; when fixed F0 is unchanged, m indicates the concentration degree of rock micro element strength distribution, and its physical significance reflects the degree of nonuniformity of rock acid corrosion.pH value decreases under identical confining pressure conditions. Conversely, when subjected to the same acid corrosion, the peak stress of the rock increases with higher levels of confining pressure. This corresponds with Wang’s experimental results, indicating that the rock damage constitutive model based on Weibull distribution and SMP criterion constructed in this study can accurately reflect the changes in rock strength under different pH corrosion and confining pressures, thereby demonstrating the feasibility of defining chemical damage factors considering pH value and time. Defining water damage variables based on the moles of soluble cementitious material was lost in the reaction with water instead of macroscopic damage variables.By observing The present article centers on rocks that are susceptible to chemical erosion and aqueous deterioration. The present study analyzed available experimental data, which revealed that the corruption of rock mechanical properties due to chemical corrosion and water damage can be attributed to the loss of soluble cementitious material present in the rocks. The article provided a quantification of both the chemical and water damage incurred by the rocks. A constitutive model was established for the chemical corrosion-water-confining pressure coupling damage in rocks based on damage theory. The study focused on the damage evolution characteristics of the rocks. The following deductions were made.(1)DS considering chemical damage, water damage and mechanical damage is deduced, and the rock damage constitutive model considering chemical-mechanics-hydro (C-M-H) coupled damage is established, which can reflect the stress–strain characteristics in the process of rock triaxial compression: With the increase of confining pressure, the peak stress and strain of rock under the same conditions increase; chemical damage and water damage will lead to the decrease of rock strength, and the degree of decrease will increase with the decrease of pH value.The spatial mobilized plane (SMP) criterion considering axial stress is introduced, the total damage variable (2)pH 3, 4, and 7, and a chemical damage factor is defined that coupled the pH value and duration of exposure. The proposed damage constitutive model employs the extremum method to ascertain the two Weibull distribution parameters (m and F0) by theoretical derivation and exhibits satisfactory conformity between the theoretical and experimental curves. The damage constitutive model can be consistent in the stress–strain characteristics of the rock triaxial compression process, which verifies the rationality and reliability of the model parameters.Stone is selected as the sample for acid corrosion treatment at (3)m and F0 under the SMP criterion are still closely linked to the strength of rock microelements and the macroscopic average strength of rock. The analysis of 13 groups of comparative data shows the stress peak of the curve increases with the increase of damage model parameters F0 and m. At constant confining pressure, the parameter m shows an overall increasing trend with decreasing pH value. The larger the value of m, the greater the degree of corrosion difference of the rock body in the region. When m is unchanged, as F0 increases, rock peak strength increases.The parameters (4)In terms of the validation of the rock damage constitutive model considering chemical-mechanics-hydro (C-M-H) coupled damage, this study adopts the experimental data from the current literature to validate the chemical damage, water damage, and force damage separately, the verification method is not a true coupling. In the future, we will conduct some experiments on rocks under the coupling of water chemistry and confining pressure to further validate this damage constitutive model.(5)m and F0) can be obtained through routine triaxial tests in the laboratory. The modified damage constitutive model can not only be applied to the chemical-mechanics-hydro (C-M-H) coupled damaged sandstone, but also can well describe the degree of damage and strength characteristics in the pre-peak stage under triaxial compression. It has certain theoretical significance for mining and railway construction that traverses the areas affected by acid rain and an intense rainfall climate.When considering the heterogeneity of the rock itself, the damage constitutive model established in this paper has no specific rock type parameters, and the required model parameters (


The results of our study  support the hypothesis that tested selenosteroids induce the extrinsic pathway of apoptosis by affecting the cell membrane as cholesterol antimetabolites. An additional mechanism of action is possible through a direct action of derivative 4 to inhibit PDHB expression in a way similar to steroid hormones.Cytostatic and pro-apoptotic effects of selenium steroid derivatives against HeLa cells were determined. The highest cytostatic activity was shown by derivative  Selenosteroids (SeSt) are compounds formed by attaching a selenium-moiety to a steroid molecule . Taking Last year a new method of selenosteroids synthesis was described . This meOur study aimed to compare the effects of obtained SeSt  on HeLa To test the above hypotheses, in addition to research on the HeLa cell growth rate under the influence of SeSt and their apoptosis profile, we also examined the expression of selected genes related to cholesterol synthesis and cell apoptosis as well as the possibility of SeSt interaction with the cell membrane using computational chemistry models.HMGCR encoding 3-hydroxy-3-methylglutaryl-CoA reductase, which produces mevalonate, and SQLE encoding squalene monooxygenase, which catalyzes the oxidation of squalene to 2,3-epoxysqualene; the other two enzymes are CYP51A1 encoding monooxygenase from the cytochrome P450 superfamily, which participates in cholesterol synthesis by removal of the methyl group at C-14 position from lanosterol . The above-mentioned studies showed that the length of the carbon chain between the oxygen at the C-3 and NCSe groups is important for the cytotoxic properties of the derivative. The 2–8 carbon-linker derivatives had better cytotoxic properties compared to the shorter and longer linker derivatives. Therefore, optimization of the length and structure of the linker is a promising direction in the chemical synthesis of derivatives with the best cytostatic properties. If the length of the hydrophobic elements of SeSt derivatives has a significant impact on their cytotoxicity, it can be assumed that the mechanism of SeSt action on cells may be closely related to the interaction with the phospholipid component of cell membranes, leading to disturbances in their structure as cholesterol antimetabolites. This hypothesis is supported by the results of recent studies where it has been shown that some SeSt significantly increase the level of ROS in cells .2–4, we analyzed the profile of cell viability and apoptosis under the influence of these SeSt as well as the expression of genes involved in the mevalonate pathway of steroid synthesis and the process of cell apoptosis.To propose the mechanism of action of the studied selenosteroids Analyzing the survival and apoptosis profiles of cells under the influence of the tested SeSt, we found that all of them have a pro-apoptotic effect on HeLa cells to varying degrees. The observed effect was dependent on the concentration of SeSt compare .2, where even at a concentration of 200 µM, live cells predominated (85.6%), but still there were fewer of them than in the control (95.6%); at the same time, the number of dead and apoptotic cells increased from 2.0% and 2.4% in control up to 4.2% and 10.2% in culture with 2, respectively , 9.4% dead cells, and 58.1% viable cells  has a much lower proapoptotic effect. The intensity of the effect we observed was also correlated with the length of the carbon linker between the selenium attached to the C1 carbon of the A ring of the base steroid. A much stronger pro-apoptotic effect was noted in the case of derivative 4, which has a longer linker compared to derivative 3. The pro-apoptotic effect was also tested on steroidal ethynyl selenide derivatives where the selenium-containing residue was combined with the C-12 of the C ring, the C-6 of the B ring, or the C-17 of the D ring [4 studied in this work has similar pro-apoptotic properties to other SeSt known from the literature. In addition, our results regarding the reduction in cell growth rate and promotion of the apoptosis process indicate that a good direction of chemical syntheses to improve the cytostatic properties of the tested SeSt will be the optimization of the structure and length of the carbon link between the selenium atom and phenol moiety in the described group of SeSt derivatives.There are limited data in the literature on the effect of selenosteroids on the apoptosis process. The pro-apoptotic effect of selenosteroids on HeLa cells in vitro was found in the case of derivatives containing N-phenyl selenourea attached to the C3 position at the steroid molecule . In thesHMGCR, SQLE, CYP51A1) was observed for compounds 2 and 3 compared to cells cultured in the presence of compound 4 and the control culture. In contrast, PDHB gene expression was significantly decreased in culture with 4, while the other compounds did not change their expression relative to the control. The presence of compound 2 in the culture medium increased the expression of the pro-apoptotic gene BID in HeLa cells compared to cells cultured in the presence of compounds 3 and 4 where the level of this transcript did not significantly change compared to the control. However, in the case of the APAF1 gene, whose product is an essential factor of the apoptosome [2 and 3, as well as a tendency for reduction of its expression in the case of compound 4 in comparison with the control  was reported in different types of cancer cells [The significant increase in ll known ,21. Alther cells ,24,25,26BID gene. The BID protein is related to that pathway because it is activated by caspase 8, which is the key protease for the extrinsic apoptosis pathway [APAF1 expression, which is crucial for triggering the intrinsic apoptosis pathway (activation of caspase 9), may be a defensive reaction of cancer cells [The membrane destabilization may cause activation of the extrinsic apoptosis pathway, which may be indicated by overexpression of the  pathway . Procasp pathway . Complex pathway , probabler cells .Taking into consideration the above-proposed mechanism, it can be assumed that the cytotoxic effect of the studied SeSt results from their interaction with the cell membrane and induction of the extrinsic apoptosis pathway.4 in the tested experimental system  does not affect the expression of genes directly related to the mevalonate pathway as well as the proapoptotic APAF1 and BID genes. Taking into account the strongest cytostatic effect of this SeSt, it can be concluded that in this case, the cells will not have time to activate defense mechanisms, as in the case of less efficient derivatives 2 and 3. It is noteworthy that PDHB expression is reduced under the influence of SeSt 4. The protein encoded by PDHB is a key component of the pyruvate dehydrogenase complex [4. Comparing the data in 4, in addition to affecting the membranes, acts inside the cell in a way similar to steroid hormones, limiting the expression of PDHB, which may additionally enhance the proapoptotic effect of this derivative.SeSt  complex  that catG) poses within. A number of poses, substantially differing in placement, were obtained as a result. The best docking scores for SeSt 2, 3, 4 are −10.4, −9.6, and −11.6 kcal/mol, respectively. This suggests the most efficient membrane penetration by SeSt 4, which is in agreement with the in vitro experiments discussed above. Because of the best affinity, a visualization of the optimal pose for 4 is shown in 2 and 3). It is seen that SeSt 4 is deeply buried in the membrane structure, filling the empty space between the layers. Similarly, the best poses for SeSt 2 and 3 are also located here. A significant variation  in docking scores between these favorable (between the layers) and other (inside the layers) positions is noted. The behavior of cholesterol is different. Sites comparable to the favorable ones for the new derivatives  are scored by poor ratings of the order of −(5–7) kcal/mol. The best affinities  are noted at the membrane edges. These results may suggest a different mechanism for the penetration of the membrane by cholesterol and proposed chemicals. Indeed, while cholesterol is embedded inside the phospholipid layers, the new compounds are rather deposited between these layers. The consequence may be the improper functioning of the penetrated membrane leading to its destabilization and, ultimately, cell apoptosis. Because of its best docking score, the most effective agent promoting this process appears to be SeSt 4.To assess the effect of obtained SeSt on the stability of the membrane bilayer of the HeLa cells, a series of in silico experiments were performed, starting with molecular docking. As detailed below in the “Experimental” section, the procedure involved repeated dockings with the box shifting to capture all the diversity in the membrane structure. For every box position, docking calculations were performed to generate the best-scored  and coefficient of variation (h = SD/mean) are by far the largest for SeSt 4 and the smallest for the ligand-free form. This may indicate that the actual influence of this compound on membrane stability is more significant than suggested by the RMSD analysis. On the other hand, the influence of all tested SeSt on membrane destabilization is apparent. The radius of gyration (Rg), defined as the root mean distance from the axis of gyration to a point where the total mass of the structure is concentrated, is considered a gauge of the compactness of the system. Its increase may indicate a destabilization of the whole structure—for example, the unfolding of the protein or disintegration of the lipid bilayer. The Rg for the structures considered here is plotted in 2, the differences are not significant; however, Rg of SeSt 2 is surprisingly large and increases with time, which may indicate faster disintegration of the membrane. It seems to be consistent with the time evolution of RMSD, which reaches its highest value after the ninth second. A thorough clarification of this probably requires longer simulations to be carried out, however.In order to further understand the mechanism of interaction of the proposed derivatives with the HeLa cell membrane, 10 ns molecular dynamics simulations were carried out for both the membrane alone and the complexes with SeSt rane see  above. Vof 2–5 Å ,32. This4 has similar properties to other known selenosteroids and therefore can be considered as a prospective cytostatic agent. The results of our research, in contrast with the literature, allow us to conclude that the incorporation of selenium substituents into the A ring of steroid can give better cytostatic results against cancer cells, and the length of the carbon linker in the case of phenylselenium or selenocyanate derivatives is important for their action. The tested derivatives probably interact with the cell membrane as cholesterol antimetabolites, causing its disorganization and activation of the extrinsic apoptosis pathway, which may be evidenced by an increase in BID expression and reduction in APAF1 expression  after embedding of each of the compounds 2–4. Derivative 4 penetrates the membrane most readily; for that reason, it appears to be the most potent in membrane disorganization of HeLa cells. In the case of the most potent derivative, 4, an additional, intracellular mechanism is possible, causing a reduction in cell bioenergetics due to a decrease in PDHB expression.Our SeSt pression . Moreove2–4 were obtained according to the described protocol [2SO4, filtered, and the solvent removed under vacuum. The products were purified by flash chromatography. Obtained 1α-(4-chlorophenylselenyl)-androst-4-en-3,17-dione (2), 1α-benzylselenylandrost-4-en-3,17-dione (3), and 1α-phenylethylandrost-4-en-3,17-dione (4) were proved identical in all respects with the same compounds described in the literature [Compounds protocol  as folloterature .2, 3, and 4; 5 cells/mL. Initially, all cultures were maintained for 24 h on control medium without SeSt. Subsequently, in control cultures the medium was replaced with fresh, whereas in experimental variants the medium was replaced with SeSt-containing in concentrations 50, 100, and 200 µM (first we prepared stock solutions with DMSO and added to the medium in volume not exceeding 100 µL). Final concentration of DMSO in the medium did not exceed 0.2%. According to our knowledge, this DMSO concentration is neutral to cells in vitro [For evaluation of the impact of three tested SeSt . 50 values determined based on the cell growth curves plotted for individual SeSt.For the study of the relative expression of selected genes (see below), HeLa cultures were maintained as above, on media with SeSt concentrations equal to their GI260/280 absorbance ratio > 1.95 using a Nano-Drop ND-2000 spectrophotometer . cDNA synthesis was performed using a High Capacity cDNA Reverse Transcription Kit  on 1 µg of total RNA in the T-100 Thermal Cycler .Total RNA was isolated and purified using an RNeasy Mini Kit  following the manufacturer’s protocol. Total RNA integrity was verified by 1.5% agarose gel electrophoresis, identified by ethidium bromide staining and ODT method for relative quantification (ΔCT method) to calculate our data.The relative expression analysis of studied genes were measured by quantitative real-time PCR using commercially designed human QuantiTect Primer Assays (Qiagen): Hs_CYP51A1_1_SG (cytochrome P450 family 51 subfamily A member 1), Hs_SQLE_1_SG , Hs_HMGCR_1_SG (3-hydroxy-3-methylglutaryl-CoA reductase), Hs_APAF1_1_SG (apoptotic peptidase activating factor 1), Hs_BID_1_SG (BH3 interacting domain death agonist), Hs_PDHB_1_SG (pyruvate dehydrogenase E1 subunit beta), and Hs_PRS18_1_SG (s18) as normalizer and an endogenous control. Real-time PCR reaction was performed in duplicate using the SYBR Green PCR Master Mix  carried out in the CFX OPUS Real-Time PCR System . The thermal cycling conditions followed the manufacturer’s instructions. At the end of the amplification phase, a melting curve analysis was carried out on the products formed to check their specificity. Based on the standard curve , the levels of studied genes transcripts were calculated after normalization of amplification products to s18. We used the comparative CData represent the number of cells from 8–14 independent experiments. Data representing apoptotic profile and relative gene expression came from at last 4 independent experiments. The results were evaluated using the Shapiro–Wilk W-test to identify normal distribution of data and the Levene L-test for testing of homoscedastic variances. In the case of normal distribution of data and homoscedastic variances, t-Student test or Anova with RIR post-hoc test were used to compare the mean values. In the case of non-normal distribution of data, we used the nonparametric Mann–Whitney U-test to compare median values.z-axis, the box moved both along this axis and in the xy-plane. The best-score poses were automatically detected. This was done with an in-house submitting script, repeating the calculations over the subsequent grid boxes, available from the authors upon request. Since there are no reliable crystallographic structures, validation of the docking protocol is problematic and must be approximated. To carry it out, we chose a membrane model similar to the HeLa mimicking models (POPE + POPC with 30 molar-% cholesterol) resulting from exhaustive (300 ns) molecular dynamics simulations [Molecular docking studies were conducted to better understand the mechanism of interaction of the proposed derivatives with the cell membrane using the latest (1.2.5) version of the AutoDock Vina program . The Pymulations ,43 and vMolecular dynamics modeling was carried out using the NAMD 2.14 and VMD 1.9.4 programs ,45. The


In this work, we have shown for the first time that deletion of the transcription factor Satb1 in cortical neurons leads to changes in the expression of key protein kinases involved in the induction of epileptiform activity. As a result, neurons derived from mice with a Satb1 deletion are not only characterized by increased hyperexcitation but also by increased sensitivity to hypoxia and impaired hypoxic preconditioning mechanisms.2+ signaling. As a result, Satb1-null neurons are characterized by increased spontaneous Ca2+ activity and hyperexcitability when modeling epileptiform activity. As a result of the deletion of Satb1, preconditioning mechanisms are disrupted in neurons during episodes of hypoxia. This occurs against the background of increased sensitivity of neurons to a decrease in the partial pressure of oxygen, which may indicate the vulnerability of neuronal networks and be accompanied by impaired expression of the Satb1 transcription factor. Here, we show that Satb1 deletion impaired the expression of a number of key kinases and neuronal hyperexcitation in models of epileptiform activity and hypoxia.Genetic disorders affecting the functioning of the brain lead not only to the development of numerous hereditary diseases but also to the development of neurodegenerative and cognitive disorders. The result of this may be the disability of part of the able-bodied population. Almost all pathological states of the brain are characterized by serious defects in the intracellular and intercellular signaling of neurons and glial cells. At the same time, the mechanisms of disruption of these signaling cascades are not well understood due to the large number of molecules, including transcription factors that, when mutated, cause brain malformations. The transcription factor Satb1 is one of the least studied factors in the cerebral cortex, and the effects of its deletion in the postnatal brain are practically not studied. Hyperexcitability of neurons is observed in many genetic diseases of the nervous system , as well as in ischemic brain phenomena and convulsive and epileptic conditions of the brain. In turn, all these disorders of brain physiology are associated with defects in intracellular and intercellular signaling and are often the result of genetic disorders. Using Satb1 mutant mice and calcium neuroimaging, we show that Satb1 deletion in projection neurons of the neocortex causes downregulation of protein kinases PKC, CaMKII, and AKT/PKB, while a partial deletion does not cause a dramatic disruption of kinome and Ca The cerebral cortex is the crown of mammalian evolution and is the center of higher cognitive abilities that distinguish humans from other animal species . The devTranscription factor Satb1  is involved in the organization of chromatin and the regulation of the differentiation of stem cells, neurons, and osteoblasts. In the cerebral cortex, it is known to regulate the migration and maturation of somatostatin-positive interneurons, synaptogenesis, and the differentiation of neurons . Satb1 iMice with the Satb1 mutation are characterized by incomplete eye opening and an increased grasping reflex . In miceThe aim of this study was to investigate the role of the transcription factor Satb1 in the regulation of expression of key protein kinases, hyperexcitation of neurons in the cerebral cortex, and activation of the phenomenon of hypoxic preconditioning.The study was performed in accordance with the permission of the Commission on Bioethics of the Institute of Cell Biophysics of the Russian Academy of Sciences (Act708n from 23 August 2010). During the course of the study, the Acts of Humane Treatment of Laboratory Animals were observed (Council Directive 2010/63 EU).The generation of Satb1 knockout mice is described in detail by Close et al. and Goebbels et al. ,11. For 2+ and Mg2+ ions. Trypsin activity was inactivated by adding fetal calf serum, and the cell suspension was centrifuged at 300× g for 3 min. The supernatant was removed, and the cells were resuspended in a culture medium consisting of Neurobasal-A medium , 0.5 mM glutamine , 2% B-27 supplement (Thermo Fisher Scientific), and 20 μg/mL gentamicin (Sigma-Aldrich). The procedure was repeated twice. After that, 200 μL of the cell suspension was placed on round cover slips with a diameter of 25 mm  coated with polylysine and placed in Petri dishes. Five hours after the cells were attached to the glass, 1.5 mL of the culture medium was added to Petri dishes. Every 3 days, 2/3 of the culture medium was replaced with fresh medium. Cells were cultured for up to 10–14 days in vitro (DIV).The method for obtaining neuroglial cell cultures from the mice’s cerebral cortex was described in detail by us earlier . Briefly2+]i dynamics, cortical cells were loaded with a Fura-2AM fluorescent probe (Thermo Fisher Scientific), and [Ca2+]i changes were recorded using an inverted motorized Axiovert 200M fluorescent microscope  i during this period i upon activation of excitatory ionotropic NMDA glutamate receptors (NMDAR) before and after episodes of hypoxia–reoxygenation. Activation of NMDAR by the short-term (30 s followed by 10-fold longer periods of washing) application of a selective agonist, N-methyl-D-aspartate . It is interesting that WT neurons did not respond with Ca2+ signals to hypoxia and reoxygenation  . Hypoxic2+ ions through NMDAR [2+ homeostasis, regulating NMDA-dependent neuroplasticity, and suppressing apoptosis [The increased expression of phosphoinositide 3-kinase (PI3K) subunits observed with complete and partial deletion of Satb1 may create conditions for the functioning of mutant neurons against the background of increased sensitivity to NMDAR agonists since PI3K/Akt inhibits pro-death genes under conditions of excessive entry of Cagh NMDAR . Moreovepoptosis ,34,35. Tpoptosis . Along wpoptosis . Of partpoptosis . However2+ ions through NMDAR [Decreased expression of CaMKII, a kinase associated with NMDAR regulation, may contribute to neural network hyperexcitation upon deletion of Satb1. It has been established that CaMKII is activated (at T286 on CaMKIIα subunits or T287 on CaMKIIβ subunits) in response to the entry of Cagh NMDAR , and thegh NMDAR . Moreovegh NMDAR . Deletiogh NMDAR . The mecgh NMDAR . All thegh NMDAR ,44. In cgh NMDAR , which iIt should be noted that the level of expression of the neurotrophin BDNF and its receptors (Trkb) is suppressed upon complete deletion of Satb1. At the same time, it is well known that BDNF, through branched signaling cascades involving Ras/MAPK/ERK (rat sarcoma protein/mitogen-activated protein kinase), PI3K/Akt, and PLC-γ1/PKC (phospholipase C-γ1/protein kinase C), contributes to the survival of neurons in conditions of oxidative stress. It has also been found that BDNF is involved in the induction of hypoxic preconditioning ,46.2+ signaling and expression of signaling kinases can be involved in the induction of epilepsy, neurodegenerative diseases, and, in the case of severe stress on cells during hypoxia, can lead to the activation of apoptosis.Deletion of the transcription factor Satb1 in neocortical glutamatergic neurons causes downregulation of the expression of key protein kinases. This, in turn, causes increased hyperexcitability of neocortical neurons and increased epileptiform activity in the magnesium-free and bicuculine models. Deletion of Satb1 is closely associated with hypoxic events and determines the increased sensitivity of Satb1-null neurons to a decrease in the oxygen concentration in the bloodstream. Disruption of hypoxic preconditioning in neurons of the cerebral cortex coincides with a change in the expression of the key protein kinases, CaMKII, PKC, PI3K, JNK, AKT, after deletion of Satb1. These changes in Ca


Malformations of the cervicothoracic junction have been described in modern horses as well as in skeletons from museums. In the present study, we examined five historical skeletons for signs of malformations of the cervicothoracic junction and were able to detect malformations of C6/C7 in three of the five historical horses. These three historical horses were the Thoroughbred stallions Dark Ronald XX, Der Loewe XX and Birkhahn XX. The two younger stallions Der Loewe XX and Birkhahn XX had a common great grandsire with Dark Ronald XX. Twenty living German Warmblood horses, descendants of these historical stallions, were recruited for evaluation for the malformation of C6/C7. For the modern horses, we estimated the inbreeding coefficient according to Wright through their ancestors of the last 110 years, which equals 11 generations, and quantified the blood percentages and the contribution to the inbreeding of the historical stallions in percentages. Our analyses showed that the C6/C7 malformations were highly variable in the historical horse family, with Dark Ronald XX, Der Loewe XX and Birkhahn XX being affected uni-laterally at C6 and C7, uni-laterally at C6 and bi-laterally at C6 and C7, respectively. In this sample of distant descendants of the historical stallions with C6/C7 malformation, a segregation between horses with and horses without C6/C7 malformation was demonstrated. Further studies with large samples and in-depth pedigree analyses will be warranted to show the effects of influential sires on the occurrence of malformations of the cervicothoracic junction in today’s Warmblood population.Malformations of the equine cervicothoracic junction affect the C6 and C7 cervical vertebrae, the T1 thoracic vertebra and in variable extent the first and second sternal ribs. To date, the clinical impact of this malformation, its prevalence and mode of inheritance in equine populations are not yet determined. We examined five skeletons for signs of malformation of the cervicothoracic junction, including three skeletons from widely used Thoroughbred stallions affected with the malformation and two skeletons serving as a comparison. The three affected historical horses were the Thoroughbred stallions Der Loewe XX, Birkhahn XX and their common great grandsire Dark Ronald XX. Malformations of C6 and C7 showed a large variation between the three stallions, as Dark Ronald XX, Der Loewe XX and Birkhahn XX were affected uni-laterally at C6 and C7, uni-laterally at C6 and bi-laterally at C6 and C7, respectively, with varying grades. In order to evaluate whether or not these malformations are incidental, we took a random sample of 20 living German Warmblood horses, which are distant descendants of these stallions. This sample consisted of ten controls and ten horses with malformations of C6/C7. Blood proportions of the historical sires in the modern Warmblood horses ranged from 0.10 to 6.25%. The contribution to inbreeding in each individual horse of our selected horse group by those sires was expressed as a percentage of the total inbreeding coefficient and ranged from 0.01 to 17.96%, demonstrating their influence on the modern Warmblood. In the present study, we were able to describe the variability of the malformation of C6/C7 within a horse family including historic and modern horses. Additionally, we detected variations appearing in connection with malformations of the cervicothoracic junction that have not been described in the literature yet. This is the first time that the malformations of C6 and C7 have been described within a familial context, providing hints on inheritance in Thoroughbreds and Warmbloods. It is worthwhile to carry out further studies in a larger setting to gain more comprehensive insights into the inheritance of the malformation and the role of important ancestors. The equine cervical spine consists of seven vertebrae C1–C7). While C1 and C2 are highly specialised, C3–C5 are rather uniform. In contrast, the sixth and seventh cervical vertebrae, which are involved in the formation of the cervicothoracic junction of the equine cervical spine, show some morphological differences. The dorsal spinous process is only indicated as a tubercle at C6 [–C7. WhilIn the equine cervical spine, the transverse processes are extended into long ventral and dorsal tubercles that serve as attachment sites for the large muscle masses of the equine neck, including the splenius cervicis muscle, the longus colli muscle, the scalene muscle and the serratus cervicis muscle ,3. VentrMalformations of the transverse processes of the equine caudal cervical spine have been discussed in recent ,13,14,15The extent of clinical signs mentioned in connection with the malformation ranges from no signs, and mild impairment due to performance failure, to the need for euthanasia due to severe health and behavioural issues ,9,17,18.Interestingly, in a study of wild foxes in Brazil, malformations of the ventral lamina on C6 and C7 were found to be similar in shape to those described in . In anotThe aim of this study was to describe the malformations in historic equine skeletons of important horses in Germany, to ascertain their pedigrees and to determine their relationship coefficients. In addition, we determined the blood flow from three of these historic horses, exhibiting a malformation of C6 and C7, in a sample of modern horses by calculating the blood proportions and inbreeding due to these three historic horses in this sample of modern horses. All modern horses were distant descendants of these three historic horses and evaluated for signs of malformation of C6 and C7. The historic skeletons of the four English Thoroughbreds Dark Ronald XX, Der Loewe XX, Birkhahn XX and Le Destrier XX, and the Hanoverian gelding Dux were provided by the Institute of Anatomy at the University of Veterinary Medicine Hannover and the Central Natural Science Collection at the Martin Luther University Halle-Wittenberg. The five skeletons were examined for malformations of the cervicothoracic junction. The available information on the horses can be found in n = 10), Oldenburg (n = 5) and Westphalian (n = 5) breed. The horses were presented for radiographic examination for malformations of the cervicothoracic junction because of suspicious clinical signs. We traced the pedigrees back to their earliest recorded ancestors which resulted in a data set of 13,285 horses born between 1860 and 2021. We examined a group of 20 German Warmblood horses presented for radiographic examination for malformations of C6 and C7. In all horses, at least 80% of the ancestors were known over 11 generations and all horses had pedigree connections to Dark Ronald XX, Der Loewe XX and Birkhahn XX. Briefly, 10 of these horses had malformations of C6/C7 and 10 horses were radiologically normal. The group consisted of 12 males and 8 females, aged 2–16 years, belonging to the Hanoverian  between Dark Ronald XX, Der Loewe XX and Birkhahn XX. Descriptive statistics were carried out using SAS, version 9.4 . PedigreDux  exhibitsThe Thoroughbred stallion Le Destrier XX  presentsDark Ronald XX  presentsDer Loewe XX  shows a Birkhahn XX  presentsThe different morphological features of all five skeletons are summarised in The additive genetic relationship coefficient (a)  between p > 0.05). The modern horses showed various combinations of malformations at C6 and C7, displaying bi-lateral malformations both at C6 and C7, bi-lateral malformations only at C6, or uni-lateral malformations at C6 and C7 on the same side of the body . The avep-Value = 0.0031). Blood proportions of the three historic stallions in the modern Warmblood horses and their sires and dams are presented in This is the first study to present three related Thoroughbred stallions with malformations of the cervicothoracic junction and a small sample of their segregating descendants. The malformations are very different in all three stallions, which is an indication of the very high variability of this trait within horse families. All three stallions were heavily used in German horse breeding, with Der Loewe XX in the Hanoverian Warmblood and Birkhahn XX in the Thoroughbred, while Dark Ronald XX was used extensively in both Thoroughbred and German Warmblood. In a current Warmblood sample from Germany, we could detect blood proportions of these stallions in horses with and without C6/C7 malformations. We were able to show that mostly Dark Ronald XX and Der Loewe XX are responsible for a small part of the inbreeding in the modern Warmbloods.Dark Ronald XX shows a grade 4/4 aplasia of the caudal ventral tubercle and a grade 1/4 aplasia of the cranial ventral tubercle of the right ventral lamina on C6 ,9,10,11,Dark Ronald XX shows a transposition of the ventral lamina to the ventral vertebral body of C7. The transposition appears ipsilaterally to the absent ventral lamina on C6. While Der Loewe XX shows no transposition of the ventral lamina, Birkhahn XX exhibits a bi-lateral transposition to C7. The uni- and bi-lateral transposition of the ventral lamina has been described in the literature ,16,23,24The arterial foramina usually appear only on the more cranially positioned cervical vertebrae, C3–C6. The appearance of additional arterial foramina has been mentioned in context of the appearance of a transposed ventral lamina ,16. All In the literature, the short spinous shape of the spinous process of C7 is described as a normal appearance . HoweverThe longus colli and longus thoracis muscles are deep perivertebral muscles. The longus colli muscle reaches from C1 to C7 and can be divided into a ventral, medial and deep layer. The longus thoracis muscle attaches ventromedially to the transverse process of C6 and reaches caudally as far as to T5 or T6, where it is positioned ventrally on the vertebral bodies . The lonThe transverse processes of C6 and C7 as well as their spinous processes serve as attachment sites for several other muscles of the cervicothoracic spine. The iliocostalis muscle attaches on the caudal margin of the first to 15th rib and the transverse process of C7 or C6 [We noticed a small tubercle on the ventral vertebral body surface of C7. In Dux, a horse with perfectly symmetrical ventral laminae, the small tubercle is slightly lateral to the median on both sides see b. The tuDysplasia, i.e., a widening of the joint space in asymmetric articular process joints (APJ) at C6/C7, was found in 4/24 and 8/8 horses with C6/C7 malformation ,17. A trThe extent to which the C6/C7 malformation can cause clinical signs is still debated. First, there is the ventral lamina itself, which may be absent at C6 and appear additionally on C7. The lamina itself probably has no effect on the clinical presentation of the horse. Rather, it is the lamina, in its function as an attachment point for the neck musculature, that causes clinical signs . In two The hypothesis is that the altered attachment point of the large cervical muscles, particularly the longus colli, leads to damage to the muscle itself. This can lead to enthesiopathies and muscle hypertrophy, causing pain in the cervical region, disturbed proprioception or axial rotation of the spine due to the constant misload ,17. In aThe arterial foramen carries the vertebral artery, vein and nerve . The varWe can conclude from historic sources that Birkhahn XX was very successful in racing sports for about three years . Dark RoDark Ronald XX was born in 1905 in Ireland and is considered one of the most important import horses in German horse breeding . He is tBorn in 1944, Der Loewe XX was a very frequently used Thoroughbred stallion in Hanoverian Warmblood breeding after the Second World War. His offspring were excellent performance horses. However, individual animals were difficult in handling . In a reBirkhahn XX was considered an exceptional talent in German racing during the period around World War II. Poor management reportedly ended the career of Birkhahn XX, before he was used for breeding in large German studs from 1951 to 1965 . In the Interestingly, Der Loewe XX and Birkhahn XX are descendants of Dark Ronald XX in the third generation. Additionally, Birkhahn XX has two common ancestors with Dark Ronald XX in ancestral generations. In the present study, we detected familiarity in horses affected with a malformation of C6 and C7. Whether or not the origin of the malformation in this family goes back to common ancestors deserves further research in museum skeletons. When we examined the historical stallions, we only identified Thoroughbred horses affected with malformations of the cervicothoracic junction, which was certainly a biased finding due to the fact that we has access to predominantly Thoroughbred skeletons. Studies from Australia predominantly report cases in the Thoroughbred breed as well ,17,18, wIn the present study, we have demonstrated the variability of the malformations of the cervicothoracic junction of the equine spine in historical skeletons from closely related Thoroughbreds. We have provided evidence that blood proportions of these historically influential sires are detectable in modern horses, with and without malformations. We have shown that C6/C7 malformations are distinct within a horse family of historical Thoroughbred and modern Warmblood horses. This is the first study to provide hints on the inheritance of the trait. As we have already found this evidence in our small sample, it is worth conducting similar studies on much larger study populations to find stronger evidence of the inheritance of the trait and to identify the role of important ancestors. Studies with larger cohorts, a standardised and published radiographic and clinical examination protocol and possibly genome-based analyses are needed to further elucidate the genetic background of the malformations and their significance for the modern horse population, especially when it comes to the effects on the wellness of the horse and their usability in sports.


The wear test was carried out on a tribometer with the use of an aggressive medium in the chamber. After each wear cycle on the tribometer, the samples were exposed to corrosion action in a corrosion test bath. Analysis of variance revealed a significant influence of rotation speed and load due to wear on the tribometer. Testing the difference in the mass loss values of the samples due to corrosion using the Mann–Whitney U test did not show a significant effect of corrosion. Steel X20Cr13 showed greater resistance to combined wear, which had a 27% lower wear intensity compared to steel X17CrNi16-2. The increase in wear resistance of X20Cr13 steel can be attributed to the higher surface hardness achieved and the effective depth of hardening. The mentioned resistance is the result of the creation of a martensitic surface layer with dispersed carbides, which increases the resistance to abrasion, dynamic durability, and fatigue of the surface of the protective layer.This research was carried out with the aim of obtaining appropriate principles for describing the influence of working parameters and the aggressive action of an acidic medium on the wear and corrosion resistance of martensitic stainless steels. Tribological tests were performed on induction-hardened surfaces of stainless steels X20Cr13 and X17CrNi16-2 under combined wear conditions at a load of 100 to 300 N and a rotation speed of 382 to 754 min The problems of friction and wear in practice are very complex due to the unfolding of various tribological processes. Especially in the process industry, e.g., food and petrochemical, there are frequent examples of complex wear, where the materials in contact are not only exposed to mechanical wear but can also be influenced by a corrosive environment. Under such conditions, the wear intensity of tribological contacts cannot be simply predicted based on wear resistance without corrosion or corrosion resistance in the absence of friction. The reason for this is that the mentioned parameters are not independent of each other, and their synergistic effect can significantly increase the rate of material degradation ,2. This Former research into the tribocorrosion resistance of stainless steels has been carried out in several directions. Most of the research was carried out on tribometers  to determine the amount of wear and the friction factor at lower loads 5 to 50 N) and rotation speeds in the presence of acidic electrolytes 6 pH ,4. Indus to 50 N The mechanical response of the tested stainless steels under tribocorrosion conditions is influenced by electrochemical conditions: both mechanical wear and wear-accelerated corrosion increase with the applied potential. In addition, delamination is the main wear mechanism that takes place under tribocorrosion conditions in the tested stainless steels. Accumulated deformation caused by sliding during tribocorrosive tests leads to low-cycle fatigue. Friction coefficients below 0.6 promote nanowear and higher wear rates are achieved when the friction coefficient increases .The real possibility of protecting machine parts in the process industry is certainly the appropriate choice of materials for tribosystem elements, as well as the choice of procedures for protecting surfaces from wear. In particular, stainless steels are chosen, and their mechanical properties and tribocorrosion resistance depend on the chemical composition and applied heat treatment. In the case of martensitic stainless steels, a good combination of mechanical properties was achieved by varying the temperature of austenitization and tempering and the duration of tempering. Corrosion current density and passivation current density vary with the temperature of austenitization. This variation can be attributed to the influence of some dissolved elements such as chromium, molybdenum, nickel, and carbon ,8,9. On Most authors analyze resistance to corrosion wear in a certain aggressive medium ,14,15,16This paper presents an experimental investigation of the influence of load and rotation speed, as well as the aggressive effect of media on the resistance of modified surfaces of stainless steels in combined wear conditions.For the purpose of conducting experimental tests, martensitic stainless steels X20Cr13 and X17CrNi16-2 were selected in a primary state. From round steel bars, samples of the dimensions and shapes required for the planned tests were machine-made. The spectrometric method was used to determine the chemical composition, and the tests were performed with the BELEC device. The chemical composition of the selected steels is shown in The heat treatment of martensitic steel samples was carried out by induction hardening as follows: frequency 19 kHz, energy 45%, austenitization temperature 1050 °C, emulsion quenching.3 and 30 mL HCl in water. The Vickers Hv1 method was used to measure the microhardness of induction-hardened samples in a cross-section from the edge to the core. The mentioned tests were carried out on the DURIMET Leitz device . Analysis of the microstructures of the experimental materials (X20Cr13 and X17CrNi16-2) after modification of the surfaces by the induction hardening process shows a high concentration of secreted precipitates that decreases with distance from the surface . The samples of martensitic stainless steels were etched with a solution of 10 mL HNOThe measured microhardness values of the induction-hardened X20Cr13 and X17CrNi16-2 steel samples, as well as the determined effective hardening depth (EHD), are shown in Tests of resistance to combined wear are divided into two parts. The first part of the test of resistance to combined wear of the samples consisted of tests on the SMT-1 device for friction and wear control, in disc/counter body (slipper) contact , with thThe contact between the surface of the disc sample and the counter body (slipper) is realized under conditions of sliding friction with the presence of microabrasive particles.The test on the tribometer SMT-1 was carried out through two cycles of 11,460 revolutions per cycle. The austenitic stainless steel X2CrNiMo17-12-2, which has a basic chemical composition (wt%)  was used3, and a fracture toughness of 1.6 MPa.As an aggressive test medium on the SMT-1 tribometer in the chamber, a heterogeneous mixture of standard quartz sand OTTAVA AFS 50/70 and a solution of acetic acid in distilled water with a volume concentration of 558 ppb was used, which corresponds to an acidity of pH 5. The amount of quartz sand was 10% by volume relative to the solution. The specified sand has a hardness of 1150 Hv, a density of 2150 kg/mIn order to create conditions for managing friction and wear processes in basic tribosystems, it is necessary to know the working parameters. The basic quantities used to identify the conditions for making contact are the speed of relative movement and the load at the point of contact .Therefore, the goal of conducting the experiment is to determine the influence of operating parameters on the resistance to combined wear of modified sample surfaces. Since the test sample on which the output quantity (change in mass) is measured is a disk that rotates with the possibility of choosing the number of revolutions of the shaft, the first influencing factor will be the speed of rotation. Another influencing factor is the load on the upper sample that is at rest.2) with two factors (load and rotation speed), each at three levels for each of the two materials. In order to make it clearer what the test conditions are, and for a clearer presentation of the wear resistance results, The test was carried out according to the factorial design of the experiment , where −4 g).After testing the resistance to combined wear (on the SMT-1 tribometer and in a corrosion test bath), samples of martensitic stainless steels (X20Cr13 and X17CrNi16-2) were assessed and the weight of the discs was measured on an analytical balance , which is shown in F-value of the model is 27.13, which favors the selection of the model because the probability that such a large value appears due to noise is only 0.01%. Members with p-values less than 0.05 are significant for the variance of the output size. From p < 0.0001), the product of load and rotation speed, AB (p < 0.0001), the square of rotation speed, B2 (p = 0.0003), and the product of load and square of rotation speed AB2 (p = 0.0155). The obtained p value of 0.0603 for the impact of load is greater than the significance level of 0.05, but this member cannot be excluded from the model considering that it appears in member AB2 whose influence is significant in the model.The p < 0.0001), which supports the selection of this model for the estimation of mass change. For the proposed response surface model, a mathematical model with coded factor values was developed, which is translated into a model with real factor values. Equation (1) shows the mathematical model of the dependence of the sample mass change on the load and rotation speed with the actual values of the factors for the X20Cr13 steel in the induction-hardened state.Moreover, in The influence of the load factor (A) and the rotation speed (B) can be shown graphically by observing the minimum and maximum value of each factor, as well as the amount of the output quantity. In this way, the tendency of the behavior of the output quantity with regard to the change of the input quantities is visible. −1 and values at a load of 300 N and a speed of 382 min−1 can be singled out.Areas of greater mass change are shown in green and areas of lesser mass change are shown in blue. From the diagram in The analysis of the influence of load and rotation speed on the mass change for X17CrNi16-2 steel in the induction-hardened state is presented in 0.2 with the addition of a constant term of 0.06 in order to obtain positive values for mass change.The variance analysis suggested a transformation of the type (y + k)p-values less than 0.05 are significant for the variance of the output size.The F-value of the model is 226.86, which favors the selection of the model because the probability that such a large value appears due to noise is only 0.01%. Members with p < 0.0001), the speed of rotation, B (p < 0.0001), the product of the load and the speed of rotation, AB (p < 0.0001), the square of the load A2 (p = 0.0010), the square of the rotation speed, B2 (p < 0.0001), and the product of the square of the load and the rotation speed A2B (p = 0.0117). Moreover, in p < 0.0001), which supports the selection of this model for the estimation of mass change.From For the proposed response surface model, a mathematical model with coded factor values was developed, which is translated into a model with real factor values. Equation (2) shows the mathematical model of the dependence of the sample mass change on the load and rotation speed with the actual values of the factors for the X17CrNi16-2 steel in the induction-hardened state.From the graphic representation of the tendency of the behavior of the output size with respect to the change of the input sizes , it can −1, while at the highest rotation speed a negligible loss of mass is noticeable regardless of the load.The region of the largest mass change is at a load of 200 N and a rotation speed of 382 minBased on the presented results of mass loss measurements due to corrosion , dependip values of the Mann-Whitney U test.Differences in mass loss values due to corrosion were tested for each individual condition using the Mann–Whitney U test. The Mann-Whitney U test is used to compare two independent groups of data when one dependent variable is ordinal or continuous and does not have a normal distribution. p = 0.709841).From In order to see the interaction effect due to the wear on the tribometer and the corrosion effect in the bath for corrosion testing, a quantitative presentation of the average wear intensity values of the tested samples was made. These results were calculated on the basis of the mean wear intensity values from x-axis of the histogram all test conditions (parameter combinations) for both induction-hardened steels, higher wear resistance was achieved by steel X20Cr13 in conditions one, two, three, four, and seven with an average value of wear intensity IwX20Cr13 = 1.22 × 10−5 in all conditions.Observing on the wX17CrNi16-2 = 1.68 × 10−5, compared to steel X20Cr13, which proved to be more resistant.Steel X17CrNi16-2 had higher resistance to wear only in conditions six, eight, and nine. In other conditions, it wore more significantly with an average intensity of wear IAfter the combined wear test (on tribometer and in a corrosion test bath), wear marks were recorded on working surfaces of the discs.In In In In Corrosion products on the surfaces of the discs for both steels after the action of the aggressive medium in the bath are not very pronounced. Underneath the corrosion marks, the shine of the base material can be seen.Based on this research concerning the influence of rotation speed and load on the resistance of the hardened surfaces of martensitic stainless steels in tribocorrosive wear conditions, several conclusions were reached.−1 for X20Cr13 steel, and 100 N/764 min−1 for X17CrNi16-2 steel.Statistical processing of the obtained data showed a significant influence of rotation speed and load. Further processing of the data by regression analysis resulted in mathematical models that exactly define the interrelations of the influencing parameters and correspond very well to the experimental data. Furthermore, the results of this research showed several significant combinations of load and rotation speed where the least wear was achieved. The most favorable combination of parameters for steel in the hardened state is the combination of 200 N/764 minAfter analyzing the results of the corrosion resistance test using the gravimetric method, no statistically significant influence of corrosion on the mass loss of the test samples was determined. If the average values of corrosion rates are compared, the induction-hardened steel X17CrNi16-2 compared to X20Cr13 has a 9% lower corrosion rate. Better anti-corrosion properties of steel X17CrNi16-2 are found in the higher content of chromium and nickel, which additionally increase the corrosion resistance.The comparison of the intensity of combined wear showed greater resistance to combined wear in X20Cr13 steel, which had a 27% lower wear intensity compared to X17CrNi16-2 steel. The higher wear resistance achieved can be attributed to the higher surface hardness and effective hardening depth of 2.25 mm in X20Cr13 steel compared to 1.25 mm in X17CrNi16-2 steel.The mentioned resistance is the result of the creation of a martensitic surface layer with dispersed carbides, which increases the resistance to abrasion, dynamic durability, and fatigue of the surface of the protective layer. The applied procedure for surfaces modification of martensitic stainless steels provides resistance in combined wear conditions, where there is a synergistic effect of mechanical wear and the aggressive action of an acidic medium.


The temporomandibular joint (TMJ) of dogs is a bilateral joint mainly used for chewing, and subsequently, an area where pathologies are frequently seen. Computed tomography (CT) represents a very important imaging modality used to diagnose TMJ diseases in dogs. A three-dimensional representation of CT images created by a volume rendering method (3DVR) could improve our understanding of the alterations in this joint. In this study, we assessed 3DVR as an ancillary method for the description and diagnosis of TMJ pathologies in dogs.Based on computed tomography (CT) images, volume rendering was used to obtain a three-dimensional representation of data (3DVR). The aims of this study included: describing the bone anatomy of the temporomandibular joint (TMJ) of dogs; comparing the TMJs of each dog by skull type and age; comparing 3DVR images with three-standard-plane CTs; assessing soft tissues adjacent to the TMJ and assessing pathological cases. Multidetector computed tomography scans of bilateral TMJs of 410 dogs were observed. From a ventral view, slight displacements in the positions of the skulls were seen, whereas from a caudal view, differences in amplitude of the articular space were observed. Dolichocephalic and mesaticephalic dogs showed more similar TMJ features than brachycephalic dogs. The shape of the TMJ bones were irregular in dogs under 1 year old. The 3DVR images related to the three-standard-plane CT improved the overall comprehension of the changes in the articular space amplitude and condylar process morphology. The fovea pterygoidea, mandibular fossa and retroarticular process were perfectly shown. A better spatial situation of adjacent soft tissues was obtained. The 3DVR represents an ancillary method to the standard-plane CT that could help in the understanding of the anatomy and diagnoses of different pathologies of the TMJ in dogs. The temporomandibular joint (TMJ) of dogs is a bilateral synovial condylar joint that plays an important role in chewing, swallowing, oral health and nutrition . This joComputed tomography is a cross-sectional imaging modality based on the absorption of patient X-rays . This imstandard planes for displaying [multiplanar reformation (MPR), data are stacked along this axis to create a volume, and then re-sliced along the other planes to create sagittal, dorsal or oblique scans [The transverse , sagittal and dorsal planes are considered the splaying . Throughue scans ,12,13.volume rendering (VR) image, which is a three-dimensional representation of data [Acquired CT data can be used to create a  of data ,16,17,18 of data . VR achi of data . Althoug of data ,15,19, 3 of data ,21 and vsegmentation, which is the process of selecting data to be included in a 3D image. Region- of- interest editing is the most basic method of segmentation. A region of interest is manually removed, drawing a rectangular, elliptical or other shape using a sort of virtual scalpel to “cut” the defined region [Images obtained using 3DVR can be reformatted by a computer program called d region ,21. Thisd region . Automatd region .In veterinary scientific literature, descriptions of normal dog TMJs using a CT scan can be found in a PhD project , as wellThe objective of this study was to show that 3DVR images could provide excellent anatomic detail of the bone structures of TMJ in dogs, supporting the interpretation of CT standard planes  and better understanding of joint anatomy. To obtain this objective, we focused on four points: (1) Providing a detailed description of the bone anatomy of TMJ using 3DVR images; (2) Assessing each TMJ according to the skull type and age of dogs using 3DVR images; (3) Assessing each TMJ by comparing 3DVR images with the 3-standard-plane CT; (4) Providing a pictorial essay of 3DVR images in some pathological cases.n = 6; 1.46%), mesaticephalic  and brachycephalic  groups.The Diagnose Imaging Service database at the Clinical Veterinary Hospital of the University of Córdoba (Spain) was searched for CT scans of the skulls of dogs from January 2021 to June 2023. A total of 410 CT scans were studied: 233 male (56.8%) and 177 female (43.2%) dogs, aged between 2 and 12 years. According to previously described skull types [n = 88; 21.5%); orbital and salivary glands ; external, middle and inner ears ; calvarium and encephalic  diseases; and oral cavity and masticatory apparatuses, including temporomandibular joints . Only 10 animals were studied for specific problems in the temporomandibular joint.Dogs underwent skull CTs for a variety of reasons, including: nasal cavity and frontal sinus pathologies  . The standard protocol was 120 kVp and 100–300 mA, with a 512 × 512 acquisition matrix. Sequential transverse CT slices of 0.6  and 1.25 mm thicknesses  were obtained ,27.Dogs were placed in a sternal decubitus position with the mandibles parallel to the table using positional aids. Dogs were restrained using general anesthesia, premedicated with methadone (0.3 mg/kg IM) and dexmedetomidine ; anesthesia was induced using dose-effect propofol (IV) and maintained with isofluorane at 100%. Dogs’ mouths stayed slightly opened to place the endotracheal tube.A contrast CT using iohexol  injected in the cephalic vein was performed after a plain CT to evaluate soft tissues.All images were transferred to a DICOM workstation, and then CT images were analyzed with an open-source media image viewer Horos©  program distributed free of charge under the LGPL license at Horosproject.org and sponsored by Nimble CO LLC d/b/a Purview in Annapolis, MD, USA).An evaluation of the whole skull of each dog was performed using the 3 standard planes of CT . Images were assessed following algorithms of bone  and soft tissues  . ResultiImages obtained using 3DVR were reformatted by segmentation, as shown in All images were independently examined by two radiologists with more than 15 years of experience in performing and reading CT scans. Results were revised for consensus by participation of a third radiologist. The evaluation was carried out following established criteria for normal (22) and abnormal TMJs .The 3DVR images were segmented rostral to the ramus of the mandible to highlight the different anatomic structures of each aspect of the joint.lateral view, it is possible to see the relationship between the TMJ and ramus of the mandible. The ramus of the mandible corresponds to the caudal non-tooth-bearing vertical part of the bone. It contains three processes: the coronoid process, which forms the most dorsal part of the mandible; the condylar process, which is transversely elongated, forming the temporomandibular joint by its articulation with the mandibular fossa of the squamous temporal bone; and the angular process, which, in a caudoventral position, serves as an attachment for the masseter and digastricus muscles [ventrolateral view provides a good, detailed image of the mandibular fossa and its caudoventral extension, the retroarticular process   and age The 3DVR images were segmented rostral to the ramus of the mandibles to compare rostral and caudal aspects of both TMJs. From the rostral view, the cuff of the endotracheal tube is observed. From this view, the pterygoid hamulus, bone of the hyoid apparatus and tympanic bullae are visualized. In a normal dog, the stylohyoid bone is curved to adjust to the ventromedial wall of the tympanic bulla. From a caudal view, it is possible to evaluate the asymmetry in skull position and even the differences in joints that may be produced under general anesthesia .Regardless of breed, skulls of dolichocephalic  and mesaRelated to age, the articular spaces in TMJ were wider in younger dogs under 6 months of age than in adult ones; bone margins seemed irregular in shape in dogs under 12 months old.lateral view of each TMJ revealed that the most rostral section of the temporal bone was thinner, and the articular space was wider. The medial and rostromedial views showed the location of the fovea pterygoidea, the area of termination of the pterygoideus lateralis muscle. This muscle is inserted in the medial surface of the condyle of the mandible, just ventral to its articular surface. This detail explains how transverse planes with a difference of just 0.5 mm or less may offer a different morphology of the TMJ in transverse planes  Alteration of the thickness of the subchondral temporal bone ; (2) Changes in the size of the articular space ; (3) Changes in the shape of the medial aspect of the condylar process . These changes can be seen in adult  and younFour pathological cases were selected to assess the TMJ by 3DVR, including an abnormal joint adjustment , subchonIn this study, a detailed description of the bone anatomy of the TMJs in dogs is provided using 3DVR images. Our aim was to show that 3DVR images represent an ancillary method to the standard planes in CT to ease understanding of the anatomy and diagnoses of the different pathologies of the TMJ in dogs. Using 3DVR provides excellent images of all the bone components of the joint, focusing on the shape and spatial relationships among the different bone structures ,17,18. ISeveral factors must be considered to obtain high-quality and high-resolution images using 3DVR. In our study, we used 120 kV and 100–300 mAs, with slices of 0.6 and 1.25 mm and a pitch of 1 and 0.75, respectively. In another study of dogs using CT images of the TMJ , the autIn the present study 3DVR images of the TMJ were greatly descriptive, showing every detail of the TMJ. Until now, 3DVR images of TMJ have only been briefly studied when focusing on different alterations in craniomandibular osteopathy, dysplasia , mandiblThrough the joint assessment of both TMJs by 3DVR, slight displacements in the position of the skull were seen, especially in the ventral view, as well as differences in the amplitude of the articular spaces in the caudal view. These changes could be due to anesthesia  or from Although textbooks on the systematic anatomy of dogs  and the Related to the age of dogs, the TMJ was not fully developed until dogs were 1 year old, and articular spaces were wider in young dogs than in adult ones ,34. In oIn our study, a detailed assessment of each TMJ comparing 3DVR images with the three standard CT planes clearly improved comprehension of the changes in the amplitude of the articular space and the morphology of the condylar process, according to the level of the slice. Transverse plane CTs of different pathologies of the TMJ were found ,6, with In our study, the fovea pterygoidea in the medial aspect of the TMJ could be perfectly observed using 3DVR images. The correct observation of this fovea is fundamental to the diagnosis of a specific pathology of the muscle pterygoid lateralis. A bilateral pterygoid myositis ossificans-like lesion in dogs affecting the m. pterygoideus lateralis has been described by CT and by cone beam computed tomography (CBCT) , but no Our detailed study detected changes in the morphology of the condylar process, depending on the level of the slices in the transverse and dorsal planes. In the dorsal and transverse planes of the TMJ, the condylar process appeared as an elongated structure with an irregular shape, being thicker around the midpoint and projecting rostrally and ventrally at this level to join the mandibular ramus. This is similar to previous descriptions but have not been supported by images . In our In our study, the mandibular fossa and retroarticular process could be observed by 3DVR images, mainly from their lateral, caudal and ventral sides. According to the dog breed, different anatomical conformations of these structures were described in both a schematic representation and in the sagittal planes . As in tThe soft tissues adjacent to the TMJ were studied using transverse planes and 3DVR images. Intrinsic soft tissues of the TMJ  could not be clearly delineated using CT scans ,6,36, MDWhen selecting clinical cases, the use of 3DVR helped in the understanding of the TMJ. The abnormal adjustment between TMJs could be better detected using rostral views of the 3DVR images segmented caudally to the ramus of the mandibles than using transverse planes. There was a marked relation between alterations in the subchondral bone in the transverse and dorsal planes and in the 3DVR images. There was also a strong relation between alterations of the subchondral bone of the two bones of the joint. In our experience, the size of the cysts observed in dorsal and transverse planes correlated well with the 3DVR images. The size of the cysts could be measured similarly from the standard planes  and from the 3DVR images.Images by 3DVR should be used to assess the TMJ of dogs to improve the interpretation of the standard MPR and help further our understanding of the bone anatomy of this joint.