Pathophysiological mechanisms of adaptation of the mucosa of the gastric cardia to portal hypertension

The model of before- and intrahepatic blockage of the portal system was proposed. Modeling of before-hepatic blockage of the portal system after development of toxic liver dystrophy lead to formation of the liver cirrhosis with stable portal hypertension. Gastritis with signs of hyperplastic and atrophy processes of the mucosa, formation of erosia, inflammatory infiltration of intermediate tissue and rebuilding of the glandulae were the basis of morphological changes of gastric mucosa in rats with experimental before- and intrahepatic portal blockage. Transformation of the cardiac mucosa with expressed polymorphism occured in the patients with the portal liver cirrhosis. Dystrophic and necrobiotic changes typical of hepatic gastropathy with signs of acute or chronic gastritis, formation of inflammatory infiltrates and rebuilding of the cardial mucosa into intestinal type were established microscopically. It is possible to believe that a widening of the veins leads to venous hyperemia and stasis in the portal hypertension. Therefore the morphology of the gastric mucosa was disturbed. It was accompanied bythe indurate changes and cellular destruction with erosia formation. These erosia may be a cause of rupture of the gastric mucosa in strong vomiting in Mallory-Weiss syndrome. This hypothesis needs clinic and experimental study in the future.


Introduction
In economically developed countries, cirrhosis of the liver is one of the six main causes of death in patients aged 35 to 60 years.Geographic features of mortality from cirrhosis among men and women are similar [1].Significant geographic differences in the incidence and mortality of liver cirrhosis are observed in developing and developed regions of the world.This is due to the different level of the economy and the development of medicine [2].
Globally, an estimated 58 million people have chronic hepatitis C virus infection, with about 1.5 million new infections occurring per year [3].
One of the goals of sustainable development in Ukraine is good health and well-being to ensure healthy lifestyles and promote well-being for all, regardless of age.To solve this goal, one of the tasks is to reduce the premature mortality of the population by a quarter, including through the introduction of innovative approaches to the diagnosis of diseases [4].
Therefore the actuality for clinical and experimental researches of etiopathogenetic mechanisms of development and elimination of liver diseases and their complications.The basis of experimental research is working out the methods of the liver cirrhosis modeling, acute and chronic liver insufficiency developed with before, and intrahepatic portal blockage.
The known methods of modeling of before-hepatic blockage of the portal system include the ligation of the portal vein and its intrahepatic branches or to apply cuff on the portal vein decreasing its diameter [5,6].The animals die in hours after ligation of the main trunk of the portal vein, and in days (4 -10) after ligation of its branches.The cirrhotic changes in the liver have no time to appear [6,7].It is not possible to apply muff on the portal vein for dosage change of its diameter for small laboratory animals (rats).The portal hypertension developed in such method of modeling in dogs after some months [6].Opie [8] proposed to model the  intrahepatic portal blockage by injection of chloroform into the jugular vein in a combination of injection of culture of E. coli.The liver cirrhosis developed in 23 days [6,7].
The famous methods of modeling of before-and intrahepatic blockage of the portal system have low reproduction, it is not possible to do it in small laboratory animals.It has some technical difficulties and low economic effect.
Therefore the purpose of the research includes to elaborate some effective, easy reproductive model of before-and intrahepatic blockage of the portal system.The main purpose of the research was to study pathophysiological mechanisms of adaptation of the mucosa of the gastric cardia to portal hypertension in experiment at rats and in patients.

Experimental procedures
The first step of the research was carried out in 20 healthy adult Wistar rats with weights between 240 -280 gram in period from September to December.Intrahepatic portal blockage was modeled by intraperitoneal injection of Chloroform 0.5 ml/kg two times a week.Beforehepatic portal blockage was modeled by injection of warm (40 -5 • C) Glycerinum 0.1 ml/100 gram from 20 th day after the beginning of Chloroform injection.The pressure in the portal vein was measured by surgical polygraphe "Salyut" before and after Glycerinum injection, and also for 20 th , 25 th and 30 th days after the first Chloroform injection.Then the animals were taken out of experiment.The preparations were fixed in 10% Formaline solution on phosphate buffer pH 7.2-7.4with the temperature +4 • C. Histological sections with thickness 10, 15 and 20 mkm were colored by Hematoxilin-eosin, described and photoed by digital photocamera Mustek MDC-3000.
The pressure in the portal vein was measured and analogous histological researches of stomach preparations were done in 5 false operated animals (the control group).A maintenance of the animals including feeding, anaesthesia and euthanasia were carried out according to the rules regimenting the experiments on animals.
The second step of the research was done in 20 preparations of the cardia of the gastric mucosa in patients with the portal liver cirrhosis.The areas of the cardia of the gastric mucosa were taken within 30-45 minutes after patient's death.The preparations were fixed in fresh 10% Formaline solution in phosphate buffer pH 7.2-7.4 at temperature +4 • C. Histological sections with thickness 10, 15 and 20 mkm were colored by hematoxilin-eosin, studied under microscope, described and photos made.The statistical analysis of results was done.
The experimental procedures outlined in this section were conducted in strict adherence to a comprehensive set of ethical guidelines, including both international and national regulations.We have provided a more detailed account of the ethical rules and procedures followed during our experiments to ensure transparency and compliance with the ethical standards governing research in Ukraine and internationally.
Our research was conducted in accordance with the regulatory requirements of Ukraine and the norms widely accepted in international research practice.Specifically, we adhered to the following ethical frameworks: rights, including the protection of personal data.4. To protect the privacy and identity of individuals participating in our study, we employed encryption identifiers for personal data in accordance with the Convention on the Protection of Personal Data.
All patients who participated in our study provided written informed consent.We ensured that participants were fully informed about the nature and purpose of the research, the procedures involved, potential risks, and their right to withdraw from the study at any time without consequences.Consent forms were used to document their voluntary agreement to participate.
The experiments involving animals were conducted with the utmost respect for ethical considerations.We followed established rules and regulations governing experiments on animals, including: 1.The animals were provided with appropriate nutrition to ensure their well-being throughout the experiment.2. When necessary, anesthesia was administered to animals to minimize discomfort and pain.3. Euthanasia procedures were carried out in strict accordance with ethical guidelines to minimize any suffering experienced by the animals.
In addition to the aforementioned international guidelines, our research also adhered to specific institutional policies and ethical review processes at our university and affiliated institutions in Ukraine.These policies encompassed a range of ethical considerations, including patient consent, animal welfare, and the handling of biological samples.

Results and discussion
The mean pressure in the portal vein was 58.6 ±6.72 mm H 2 O in rats of control group.The mean pressure in the portal vein was 78.8 ±9.43 mm H 2 O on the 20 th day after the experiment began, 223.4 ±21.71 mm H 2 O on the 25 th day, 244.0 ±20.56 mm H 2 O on the 30 th day.The mean pressure in the portal vein was 323 mm H 2 O on the 30 th day.Weak relationship between an increasing of the portal pressure and the experiment was revealed in the 20 th day of experiment.There was strong direct correlation on the 25 th and the 30 th day of experiment.The coefficient of correlation and its range was 0.512 ±0.43 (p<0.1) for study of control data and data of the 20 th day experiment, 0.965 ±0.11 (p<0.001) for study of control data of the 25 th day experiment, 0.981 ±0.17 (p<0.001) for study of control data and data of the 30 th day experiment.The strong direct correlation between an increasing of the portal pressure and term of experiment was established in comparison data between series of experiment.The coefficient of correlation and its range was 0.953 ±0.28 (p<0.001) for study of data of the 20 th day and data of the 25 th day experiment, 0.961 ±0.27 (p<0.001) for study of data of the 20 th day and data of the 30 th day experiment.The results of the 25 th day experiment were correlated with the 30 th day experiment (0.615 ±0.45, p<0.05).
The changes in the liver parenchyma to be analogous to the toxic liver dystrophy was revealed.The partial necrosis of hepatocytes was discovered, mainly in the center of lobes.There was adipose dystrophy.The relief of the lobes was changed and absent in some parts of the liver.The liver acquired a view of Muscat (figure 1).It may divide some areas of the liver tissue of preserved lobulae in the 20 th day of experiment, showed loss of its specific view (figure 2, 3).
In the 30 th day of experiment some areas of the liver tissue with necrosis, adiposal distrophy, disintegration of hepatocytes with formation of indefinite blockes appeared (figure 3).Areas of increasing connective tissue were revealed.The cirrhosis began to form.
A view of superficial gastritis was established among the 80% of the rats in the 20 th day of experiment before Glycerinum injection.The epithelium loses its high-prismatic shape and stands more plain, the cytoplasm was pellucid.The nuclei pushed to the apical part of cell, were different by size and color.Borders between the cells were indistinct.
In 50% of rats the changes were according to gastritis with disturbance of the glandulae without atrophy.The glandulae and stroma were involved in process in these animals.There was vacuolization of the cytoplasm, necrobiosis of the cells, widening of the glandulae gap.An  In 20% of rats changes were analogous to atrophic gastritis and thinning of the mucosa.The glandulae were conserved in small islands among the connective tissue.There were changes in the superficial epithelium and in the epithelium of the glandulae looking for intestinal metaplasia was discovered.
A lot of animals had atrophic gastritis with thinning of the mucosa in the 30 th day of experiment.There were multiple erosia of the mucosa in 75% of cases.The submucosal level was widened.The muscular plate of the mucosa had the areas of hypertrophy.The elastic fibers were hyperplastic.
The changes of the vessels in the submucosal level were established.The veins were widened.The epithelium was desquamoused above them.It led to formation of microerosia and erosia.The walls of the veins were thickened.Tunica propria mucosae was oedematic.It had hemorrhages and areas of polymorphic cell infiltration consisting mainly of neutrophills and eosinophills.Thre was proliferation of histiocytes and fibroblasts.Besides there were plasmatic, plump cells and lymphocytes in composition of the infiltrate.
The changes of the glandulae were oppression of formation of the mucus.the gap of the glandulae was widened.There was an increase of fiberous structures in the stroma.The quantity of the glandulae was decreased in any areas.
A death of smooth myocytes and substitution of them by the connective tissue were revealed in areas of the inflammatory infiltrates of the muscular plate in the 30 th day of experiment.Sometimes the muscular plate was substituted by fibrous tissue.Hemorrhages into the mucosa and the submucosa were discovered in areas of sclerosis of the tunica muscularis mucosae.
The varices of the gastric submucosal layer and atrophy of the mucosa above them were revealed in 75% all the cases.
The sharply expressed changes of the vessels of gastric cardia were established in the patients of portal hypertension.They manifested by widening, stasis, plasmatic saturation and fibrinoid necrosis of the vessel wall (figure 4).
The desquamation of superficial epithelium was increased above widening veins.It was resulted by formation of microerosion and erosion of different degree (figure 5).Microscopic picture of such type erosion was not typical and depends on stage of the process and the depth of occurrence of the blood vessels.The walls of the vessels were thick as a result of productive vasculitis.There were oedema, hemorrhages and polymorphic cell infiltration in the tunica propria mucosae.A zone of infiltration may be distributed into the submucosal and muscular layers.The neutrophills and eosinophills composed the main part of the infiltrate.There were a lot of lymphocytes, plasmatic and plump cells.A proliferation of histiocytes and fibroblasts was revealed.The lymphocytes and plasmatic cells predominated in small infiltrates (figure 6).
The formation of mucus in the gastric glandulae occured unevenly in zone of inflammatory infiltration.There were cells having significant amount of mucus granules and cells having cytoplasm filled to overflowing of mucus.Some of them lose a connection with the basal membrane and desquamated into the aperture of the glandulae.There was oppression of secret formation in the glandulae epithelium (figure 7).
A combination of dystrophic changes of the glandulae, hyperplastic and atrophic processes in the gastric mucosa with formation of erosia, an inflammatory infiltration of intermediate tissue and changes of the glandulae are the basis of morphological changes of the gastric mucosa in the patients with the portal liver cirrhosis.A cellular composition of the glandulae and a depression of their fumctional activity were connected with dystrophic changes in the gastric mucosa.Borders between the cells were indistinct.Nuclei looked like bubble with hyperchromatosis of the nuclear membrane or piknotic (figure 8).

Conclusion
Results of the research allow to constant that it is necessary to create the complex effect for reliable modeling of the liver cirrhosis.Weak expressed portal hypertension during formation of model of the intrahepatic portal blockage was revealed.However such increasing of pressure in the portal vein was not stable.A sharp increasing of the pressure in the portal vein was established after modeling before-hepatic blockage of the portal system.Modeling of before-hepatic blockage of the portal system after development of toxic liver dystrophic lead to formation of the liver cirrhosis with stable portal hypertension.Gastritis with signs of hyperplastic and atrophy processes of the mucosa, formation of erosia, inflammatory infiltration of intermediate tissue and rebuilding of the glandulae were the basis of morphological changes of gastric mucosa in rats with experimental before-and intrahepatic portal blockage.
Transformation of the cardial mucosa with expressed polymorphism occured in the patients with the portal liver cirrhosis.Dystrophic and necrobiotic changes typical for hepatic gastropathy with signs of acute or chronic gastritis, formation of inflammatory infiltrates and rebuilding of the cardiac mucosa into intestinal type were established microscopically.It is possible to believe that a widening of the veins leads to venous hyperemia and stasis in the portal hypertension.Therefore the morphology of the gastric mucosa was disturbed.It was accompanied by the indurate changes and cellular destruction with erosia formation.These erosia may be a cause of rupture of the gastric mucosa in strong vomiting in Mallory-Weiss syndrome.This hypothesis needs clinic and experimental study in the future.

Figure 1 .
Figure 1.The liver acquired a view of Muscat in the 20 th day of experiment.

Figure 2 .
Figure 2. Liver cirrhosis formation in the 30 th day of experiment.

Figure 3 .
Figure 3. Expressed changes in the gastric mucosa in portal hypertension.1 -sharply widening vein with stasis and fibrinoid necrosis of the wall.Hematoxilin-eosin.x200.

Figure 6 .
Figure 6.Oppression of secret formation in the epithelium of glandulae in zone of inflammatory infiltration.A part of glandular cell has no connection with the basal membrane, desquamation into aperture of the glandulae (arrow).Hematoxilin-eosin.x200.

Figure 7 .
Figure 7. Borders between the cells were indistinct.Nuclei looked like bubble with hyperchromatosis of the nuclear membrane or picknotic.Hematoxilin-eosin.x400.

Figure 8 .
Figure 8. Polymorphic cell infiltration in the gastric holes of the tunica propria mucosae.Transformation of the gastric mucosa into intestine type.Hematoxilin-eosin.x50.