DEVELOPMENT OF A MATHEMATICAL MODEL OF LIVER FILTRATION

Клетки печени занимают центральное место в реакциях промежуточного метаболизма. Печень принимает участие в метаболизме почти всех классов веществ. Основной структурной единицей печени является печеночная долька, которая представляет собой призму размером 1,5-2 мм с плоскими основанием и вершиной. По всей дольке также распределены лимфатические сосуды, которые активно поглощают интерстициальную жидкость и выводят ее с регулируемой скоростью, однако зависимость скорости поглощения от интерстициального давления и других параметров известна не полностью. В работе представлена математическая модель для оценки кровотока в печеночной дольке. Рассмотренная клеточная модель включает в себя производство и прохождение лимфы по двум основным путям: поглощение лимфатическими сосудами и выход из печени через поверхность дольки в интерстициальное пространство. Приведены геометрические и механические допущения модели и ее недостатки. В биологической модели исследовано влияние изменений кровяного давления в печени на выработку лимфы и оценивается скорость поглощения лимфы и поток жидкости (как лимфы, так и крови) по всей поверхности печени. В математической модели показана классификация: статическая (не зависящая от времени), пространственная, детерминированная, нелинейная, непрерывная. Результаты исследования показали, что предлагаемая клеточная модель микроциркуляции печени включает в себя производство и прохождение лимфы по двум основным путям: поглощение лимфатическими сосудами и выход из печени через поверхность дольки в интерстициальное пространство. Выявлены основные недостатки разрабатываемой модели Liver cells are central to intermediate metabolic reactions. The liver is involved in the metabolism of almost all classes of substances. The main structural unit of the liver is the hepatic lobule, which is a prism 1.5-2 mm in size with a flat base and apex. Lymphatic vessels are also distributed throughout the lobule, which actively absorb interstitial fluid and remove it at a controlled rate, however, the dependence of the rate of absorption on interstitial pressure and other parameters is not fully known. The paper presents a mathematical model for assessing blood flow in the hepatic lobule. The considered cellular model includes the production and passage of lymph through two main pathways: absorption by the lymphatic vessels and exit from the liver through the surface of the lobule into the interstitial space. Geometric and mechanical assumptions of the model and its disadvantages are presented. A biological model investigates the effect of changes in liver blood pressure on lymph production and estimates the rate of lymph absorption and fluid flow (both lymph and blood) over the entire surface of the liver. The mathematical model shows the classification: static (independent of time), spatial, deterministic, nonlinear, continuous. The results of the study showed that the proposed cellular model of liver microcirculation includes the production and passage of lymph through two main pathways: absorption by the lymphatic vessels and exit from the liver through the surface of the lobule into the interstitial space. The main shortcomings of the developed model are revealed

Single-nucleus RNA-seq2 reveals functional crosstalk between liver zonation and ploidy

Single-cell RNA-seq reveals the role of pathogenic cell populations in development and progression of chronic diseases. In order to expand our knowledge on cellular heterogeneity, we have developed a single-nucleus RNA-seq2 method tailored for the comprehensive analysis of the nuclear transcriptome from frozen tissues, allowing the dissection of all cell types present in the liver, regardless of cell size or cellular fragility. We use this approach to characterize the transcriptional profile of individual hepatocytes with different levels of ploidy, and have discovered that ploidy states are associated with different metabolic potential, and gene expression in tetraploid mononucleated hepatocytes is conditioned by their position within the hepatic lobule. Our work reveals a remarkable crosstalk between gene dosage and spatial distribution of hepatocytes.

Mitochondria Load Degree in Hepatocytes of the Classical Hepatic Lobules in Chinchilla (Chinchilla lanigera)

Hepatocytes represent the majority of the liver cell population and are arranged in the form of cords placed in intimate contact with the sinusoidal capillaries. The functional complexity corroborated with the intensity of the activity of hepatocytes requires large amounts of energy. The organelles involved in the production of chemical energy used in the activity of hepatocytes are the mitochondria. The purpose of this study was to verify the mitochondrial load of hepatocytes in all areas of the classical hepatic lobules, in order to indirectly assess the intensity of hepatocyte activity in each area. Materials and Methods Five fresh corpses of chinchilla (Chinchilla lanigera) from an independent breeder from Bistrița-Năsăud county were used. Liver fragments were harvested and fixated in Kolster’s solution for 24 hours, stained with Heidenhain ferric hematoxylin, and assessed using Olympus BX41 microscope. Fixation with Kolster's solution and the staining with Heidenhain's iron hematoxylin clearly shows the hepatocytic mitochondria in shades from gray to black. The liver lobules displayed an uneven distribution of mitochondria depending on the area. In zone 1 of the classical hepatic lobule, the degree of loading of hepatocytes with mitochondria is larger than in zone 2 and much larger than in zone 3. Morphological features of the hepatocytes, including the number and distribution of mitochondria in the hepatic lobules, should improve the understanding of the physiology and pathology of the liver.

Comparative Characteristics Of The Morphological Parameters Of The Liver At Different Periods Of Traumatic Brain Injury

The research paper described morphological changes in the liver in traumatic brain injury. The study was conducted on 28 deceased patients, whose death occurred from various causes of traumatic brain injury, that is, traffic accidents, falls from a height and, less often, injuries caused by blunt hard objects. Under the influence of craniocerebral trauma, the deceased developed pathological processes in the liver tissue, plethora of the sinusoid of the hepatic lobule, fatty degeneration of hepatocytes, followed by edema.

WHAT NEED CONSIDER AS A STRUCTURAL AND FUNCTIONAL UNIT OF THE HUMAN LIVER?

The article discusses the issues of structural and functional organization of the human liver. The analysis of classical ideas in this problem is carried out and their shortcomings are shown. The data of a number of authors are presented in whose works on the reconstruction of the hepatic lobules in humans and cats it was shown that the liver parenchyma consists of complexes of the hepatic lobules. Each complex of hepatic lobules is a combination of 2-4 classic lobules, united by one common base. The central veins in the lobules of the complex begin with the 2nd third of the length of the lobule. Merging, they form a collective vein located in the common base of the lobules. The hepatic lobule complex is morphologically and functionally combined. Separate classic hepatic lobule in the liver is rare. The author proves that portal lobules and hepatic acini do not exist as real morphological structures, since their volumetric reconstruction cannot be created.