Sovremennye Tehnologii v Medicine最新文献

Modern methodology of PET/CT quantitative analysis in patients with glioblastomas is not strictly standardized in clinic settings and does not exclude the influence of the human factor. Methods of radiomics may facilitate unification, and improve objectivity and efficiency of the medical image analysis. The aim of the study is to evaluate the potential of radiomics in the analysis of PET/CT glioblastoma images identifying the relationship between the radiomic features and the ¹¹С-methionine tumor-to-normal brain uptake ratio (TNR) determined by an expert in routine.

Materials and methods: PET/CT data (2018-2020) from 40 patients (average age was 55±12 years; 77.5% were males) with a histologically confirmed diagnosis of "glioblastoma" were included in the analysis. TNR was calculated as a ratio of the standardized uptake value of ¹¹C-methionine measured in the tumor and intact tissue. Calculation of radiomic features for each PET was performed in the specified volumetric region of interest, capturing the tumor with the surrounding tissues. The relationship between TNR and the radiomic features was determined using the linear regression model. Predictors were included in the model following correlation analysis and LASSO regularization. The experiment with machine learning was repeated 300 times, splitting the training (70%) and test (30%) subsets randomly. The model quality metrics and predictor significance obtained in 300 tests were summarized.

Results: Of 412 PET/CT radiomic parameters significantly correlated with TNR (p<0.05), the regularization procedure left no more than 30 in each model (the median number of predictors was 9 [7; 13]). The experiment has demonstrated a non-random linear correlation (the Spearman correlation coefficient was 0.58 [0.43; 0.74]) between TNR and separate radiomic features, primarily fractal dimensions, characterizing the geometrical properties of the image.

Conclusion: Radiomics enabled an objective determination of PET/CT image texture features reflecting the biological activity of glioblastomas. Despite the existing limitations in the application, the first results provide a good perspective of these methods in neurooncology.

The aim of the study was to compare type I collagen-based and methacryloyl gelatin-based (GelMA) hydrogels by their ability to form hyaline cartilage in animals after subcutaneous implantation of scaffolds.

Materials and methods: Chondrocytes were isolated from the costal cartilage of newborn rats using 0.15% collagenase solution in DMEM. The cells was characterized by glycosaminoglycan staining with alcian blue. Chondrocyte scaffolds were obtained from 4% type I porcine atelocollagen and 10% GelMA by micromolding and then implanted subcutaneously into the withers of two groups of Wistar rats. Histological and immunohistochemical studies were performed on days 12 and 26 after implantation. Tissue samples were stained with hematoxylin and eosin, alcian blue; type I and type II collagens were identified by the corresponding antibodies.

Results: The implanted scaffolds induced a moderate inflammatory response in both groups when implanted in animals. By day 26 after implantation, both collagen and GelMA had almost completely resorbed. Cartilage tissue formation was observed in both animal groups. The newly formed tissue was stained intensively with alcian blue, and the cells were positive for both types of collagen. Cartilage tissue was formed among muscle fibers.

Conclusion: The ability of collagen type I and GelMA hydrogels to form hyaline cartilage in animals after subcutaneous implantation of scaffolds was studied. Both collagen and GelMA contributed to formation of hyaline-like cartilage tissue type in animals, but the chondrocyte phenotype is characterized as mixed. Additional detailed studies of possible mechanisms of chondrogenesis under the influence of each of the hydrogels are needed.

Traumas and infectious diseases of the eye play a leading role in the development of corneal blindness responsible for 1.5-2 million cases of vision loss per year. To date, the issue of reducing the incidence of fungal keratitis is acute and needs to be solved worldwide. Trauma as a risk factor for corneal fungal disease is thought to be prevalent in developing countries due to agricultural involvement, while in developed countries the onset of the disease is predisposed by medical advances such as contact vision correction and modern ophthalmic surgery. Thorough analysis of the pathogenesis gives the possibility to describe the action of fungal enzymes, biofilm formation, and the resistance mechanism, which on the one hand explains the aggressive course of the disease and difficulties in its diagnosis, and on the other hand, it encourages searching for new methods of diagnosis and treatment. The non-specific clinical picture of fungal keratitis, the variety and availability of antibiotics nowadays become an obstacle for rapid detection of this pathology. Low public awareness and late visit to an ophthalmologist are also a barrier to successful combating the increasing incidence of fungal keratitis. Belated diagnosis, increasing resistance of fungi to antibiotics, and lack of registered antifungal ophthalmic drugs justify poor treatment efficacy resulting in decreased visual acuity or vision loss. Existing diagnostic methods need systematization and detailed comparison, identifying the advantages and disadvantages of each. This review considers causative agents and their influence on pathogenesis of the disease, describes difficulties of fungal keratitis diagnosis and possible ways of overcoming these problems using new developments, and also outlines further prospects of research in this direction.

Biodegradable and biocompatible polymers are actively used in tissue engineering to manufacture scaffolds. Biomedical properties of polymer scaffolds depend on the physical and chemical characteristics and biodegradation kinetics of the polymer material, 3D microstructure and topography of the scaffold surface, as well as availability of minerals, medicinal agents, and growth factors loaded into the scaffold. However, in addition to the above, the intrinsic biological activity of the polymer and its biodegradation products can also become evident. This review provides studies demonstrating that scaffolds made of poly(3-hydroxybutyrate) (PHB) and its copolymers have their own biological activity, and namely, osteoinductive properties. PHB can induce differentiation of mesenchymal stem cells in the osteogenic direction in vitro and stimulates bone tissue regeneration during the simulation of critical and non-critical bone defects in vivo.

The aim of the study is to develop and verify an algorithm for automatic generation of leaflet apparatus models for prosthetic heart valves, to optimize the basic parameters of the models in order to minimize the stress-strain state and maximize the geometric area of the orifice.

Materials and methods: The suggested algorithm consists of three blocks: "Generator", "Modeling", "Analysis". The first block creates a three-dimensional model of the leaflet apparatus using the specified parameters (height, radius, thickness, degree of "sagging", angle of the free edge deviation). Numerical simulation of the apparatus functioning is further performed using the finite element method. Then, the statistical analysis of the von Mises stresses is done and the opening area of the design in question is calculated.Verification was performed by comparing quantitatively the lumen areas of the leaflet apparatus in the open state, obtained from the literature data for the Trifecta bioprosthesis (19, 21, and 23 mm in diameter), with the results of the described algorithm operation.

Results: The verification of the algorithm has demonstrated the following deviations in the lumen area in the open state: 2.85% for 19 mm, 14.81% for 21 mm, and 23.17% for 23 mm models. This difference is due to the choice of the model material (no data could be found on the physical and mechanical properties of the pericardium used for the fabrication of the Trifecta bioprostheses).The generation of a large number of designs (n=1517) without fixation of certain geometry parameters has shown that thickness of the leaflet apparatus makes the greatest contribution to the degree of opening; its dependence on the thickness and arising peak von Mises stresses has been demonstrated. Of the valvular models obtained, 278 showed the opening degree greater than 80% and maximum peak von Mises stresses below 4 MPa for the proposed model of the pericardium, which is 65% below the ultimate strength of the material.Out of 278 leaflet models, 3 "optimal" designs were selected meeting the diameter criteria of 19, 21, and 23 mm. The loss index for them was 0.24, 0.19, 0.20 with the opening degrees of 88.28, 84.48, 88.12%, and maximum peak von Mises stresses of 3.62, 1.21, 1.87 MPa, respectively.

Conclusion: The developed algorithm makes it possible to automatically generate three-dimensional models of the leaflet apparatus, numerically simulate the opening process using the finite element method, statistically analyze the results obtained, and calculate the lumen area. The algorithm was verified based on the data for the Trifecta bioprosthesis of three standard sizes. The presented algorithm can be used both for the research and development of various designs and for obtaining "optimal" models of sash devices.

The aim of the study is to assess the possibility of using artificial intelligence to determine the most significant predictors of the operative correction outcomes for patients with damaged coronary and carotid arteries.

Materials and methods: The retrospective study of the simultaneous (or single-stage) surgical intervention results has been carried out in patients with combined atherosclerotic damage of the coronary bed and cerebral arteries (n=42), which was severe and extensive. The parameters which may be predictors of the cardiovascular risk were analyzed using the TADA program. Ten models were built for program learning. The model with 92% predictive accuracy appeared to be the most successful.

Results: Simultaneous correction resulted in the absence of 30-day coronary complications in all patients. With respect to the cerebral vascular territory, acute ischemic stroke developed in 2 patients. The lethality rate was 2.4%, the fatal outcome was caused by postoperative gastrointestinal bleeding.The TADA program model considered the following parameters to be the most significant predictors: internal carotid artery cross-clamping time in minutes (51.24%); damage to the left coronary artery stem (30.42%); diastolic AP (18.28%). If cross-clamping of the internal carotid artery lasts for less than 18 min, complications are not likely to occur, while they are practically inevitable if the time exceeds 46 min. The probability of complications grows nonlinearly with the increase of the extent of the left coronary artery stem injury. A high diastolic AP never virtually coincides with the presence of complications, nor does the low one. The highest probability of complications is at the values from 70 to 80 mm Hg.In patients with a triple vessel injury of the coronary arteries, a representative picture of a nonsignificant feature is observed.

Conclusion: Application of artificial intelligence for determining risk predictors for patients with concurrent atherosclerotic damage of the coronary and carotid arteries is an effective method for prognosticating the risks of simultaneous interventions.

The development of high-throughput technologies has sharply increased the opportunities to research the human body at the molecular, cellular, and organismal levels in the last decade. Rapid progress in biotechnology has caused a paradigm shift in population-based studies. Advances in modern biomedical sciences, including genomic, genome-wide, post-genomic research and bioinformatics, have contributed to the emergence of molecular epidemiology focused on the study of the personalized molecular mechanism of disease development and its extrapolation to the population level. The work of research teams at the intersection of information technology and medicine has become the basis for highlighting digital epidemiology, the important tools of which are machine learning, the ability to work with real world data, and accumulated big data. The developed approaches accelerate the process of collecting and processing biomedical data, testing new scientific hypotheses. However, new methods are still in their infancy, they require testing of application under various conditions, as well as standardization. This review highlights the role of omics and digital technologies in population-based studies.

As early as 50 years ago, bisphosphonates turned from a water treatment agent into one of the most widely used groups of drugs for the treatment of various diseases of calcium metabolism (bone tissue resorption, oncological complications of neurodegenerative diseases and others). Years of research on bisphosphonates have contributed to the understanding of their molecular and cellular pathways of their action. All bisphosphonates have a similar structure and common properties, however, there are obvious chemical, biochemical, and pharmacological differences between them. Each bisphosphonate has its own unique profile. This review summarizes data on the mechanisms of action of bisphosphonates, demonstrates the experience and prospects for their use for the modification of cardiovascular bioprostheses, since the issue of preventing bisphosphonate calcification has not been settled yet.