Sovremennye Tehnologii v Medicine最新文献

Intraoperative recording of cortico-cortical evoked potentials (CCEPs) enables studying effective connections between various functional areas of the cerebral cortex. The fundamental possibility of postoperative speech dysfunction prediction in neurosurgery based on CCEP signal variations could serve as a basis to develop the criteria for the physiological permissibility of intracerebral tumors removal for maximum preservation of the patients' quality of life. The aim of the study was to test the possibility of predicting postoperative speech disorders in patients with glial brain tumors by using the CCEP data recorded intraoperatively before the stage of tumor resection.

Materials and methods: CCEP data were reported for 26 patients. To predict the deterioration of speech functions in the postoperative period, we used four options for presenting CCEP data and several machine learning models: a random forest of decision trees, logistic regression, and support vector machine method with different types of kernels: linear, radial, and polynomial. Twenty variants of models were trained: each in 300 experiments with resampling. A total of 6000 tests were performed in the study.

Results: The prediction quality metrics for each model trained in 300 tests with resampling were averaged to eliminate the influence of "successful" and "unsuccessful" data grouping. The best result with F1-score = 0.638 was obtained by the support vector machine with a polynomial kernel. In most tests, a high sensitivity score was observed, and in the best model, it reached a value of 0.993; the specificity of the best model was 0.370.

Conclusion: This pilot study demonstrated the possibility of predicting speech dysfunctions based on CCEP data taken before the main stage of glial tumors resection; the data were processed using traditional machine learning methods. The best model with high sensitivity turned out to be insufficiently specific. Further studies will be aimed at assessing the changes in CCEP during the operation and their relationship with the development of postoperative speech deficit.

The aim of the study: We compare the effectiveness of multimodal optical coherence tomography (MM OCT) in the traditional structural OCT mode and the OCT elastography (OCE) mode in addressing two clinically important tasks: (1) detecting groups of tumor cells at surgical margins during breast-сonserving surgery (BСS) in breast cancer (BC) and (2) identifying breast tumor margins. The obtained results were correlated with corresponding histological sections.

Materials and methods: The study was performed on 100 surgical margin samples (top, bottom, medial, and lateral - four samples from each patient in total) obtained from 25 patients with BC who underwent BCS (lumpectomy), and on 25 postoperative tumor samples (to determine tumor margins). With MM OCT method, we visually and numerically assessed the scattering (level and depth of OCT signal penetration) and elastic (stiffness values, or Young's modulus (kPa)) properties of the tumor and non-tumor breast tissue and the obtained values were compared with the results of postoperative histological examination.

Results: In 4 surgical margin samples (out of 100), with the OCE method we identified groups of histologically confirmed tumor cells ("positive" resection margins) at the distance of about 5 mm from the visible tumor margin. The identified zones were larger than 0.5 mm with stiffness of more than 400 kPa in all these cases. However, the structural OCT could not identify these groups of tumors and they were not distinguishable from the surrounding fibrous tissue.In the areas of tumor into non-tumor tissue transition, structural OCT images detected tumor margins only if they were adjacent to adipose tissue and did not detect them if there were adjacent to non-tumor fibrous tissue. OCE images with high stiffness values (more than 400 kPa) and high contrast showed a clear tumor margin with both adipose and fibrous tissue.

Conclusion: The study demonstarets the potential of MM OCT, particularly its OCE mode, as a real-time method for intraoperative tumor margin and surgical margin assessment in BCS. OCE images compared to structural OCT images visualize higher contrast between different types of breast tissue (adipose tissue, fibrous stroma, hyalinized stroma, tumor cell clusters), as well as more accurate identification of the tumor border and detection of small groups of tumor cells at surgical margins. An algorithm for intraoperative MM OCT examination of the state of the resection margin is proposed in accordance with standard clinical guidelines for achieving clean surgical margins in breast cancer patients.

In recent years, decellularized tissues have evolved into a new, full-fledged platform for the creation of tissue-engineered constructions. Extracellular matrix (ECM) of each tissue provides a unique tissue-specific microenvironment for resident cells with the structure and biochemical signaling required for their functioning. The decellularized ECM (dECM) has been established to influence cell differentiation. The review provides recent data on the composition and functions of the ECM, methods for obtaining decellularized tissues, and their application in tissue engineering depending on their physical form (scaffold, powder, or hydrogel). The effect of the matrix source, decellularization and sterilization techniques on dECM composition has been considered. Regulatory mechanisms of cell differentiation by the extracellular matrix are discussed. Differences in the protein composition of the native and decellularized materials are presented. Application of dECM in the bioink composition for regeneration of various tissues using bioprinting technologies is also considered. It has been concluded that successful application of dECM in tissue engineering and regenerative medicine requires a permanent and biologically suitable dECM source, optimized tissue decellularization protocols, improved mechanical properties of dECM-derived bioinks, and prevention of immunological reaction of the organism.

The aim of the investigation was to study the level of amylolytic activity and microtomographic index of synovial fluid density as well as to substantiate their clinical and pathogenetic significance by identifying correlations with the known informative indicators reflecting characteristic features of the pathological process in various joint diseases.

Materials and methods: Samples of synovial fluid from 95 patients with various joint pathologies at the stage of the disease progression characterized by copious effusion into articular cavities have been examined. Synovial fluid samples obtained by knee arthrocentesis served as a material for the investigation. Conventional methods were used to determine the concentration of uric acid, inorganic phosphorus, total protein, and amylolytic activity level in the selected samples while X-ray density was identified by computed microtomography.

Results: All samples of pathological joint fluid have shown a high level of amylolytic activity as compared to the synovial fluid from healthy joints. The relationship between the level of amylolytic activity in synovia and specific joint pathology has been identified. It has also been found that uric acid values, inorganic phosphorus concentrations, and total protein in various types of joint damage may influence X-ray density of the synovial fluid. Correlations between the studied indices have been established.

Conclusion: New data on the level of synovia amylolytic activity has been obtained in one non-inflammatory and six different inflammatory diseases. Pathogenically determined correlation between the microtomographic index of synovial fluid density and concentrations of uric acid, inorganic phosphorus, total protein has been confirmed. Specific indicators of X-ray density of synovia in various joint pathologies as well as unidirectional and multidirectional data in comparison with the norm allow us to consider X-ray microtomography as a method that reveals additional details during investigation of synovial fluid density and brings new surrogate markers for the study of pathogenetic mechanisms of the development, differentiation, and treatment of various joint pathologies.

The aim of the study was to analyze the genome features of the probiotic strains Bifidobacterium longum 379, Bifidobacterium bifidum 1, and Bifidobacterium bifidum 791 and study their antiviral activity.

Materials and methods: Whole genome sequencing of three strains of bifidobacteria was performed on the MiSeq platform (Illumina Inc., USA). The genomes were annotated using the Prokka v. 1.11 utility and RAST genomic server. The individual genetic determinants were searched using the ResFinder 3.2, PathogenFinder, PlasmidFinder, RAST, and Bagel 4 software. The antiviral activity of the strains against influenza A viruses was studied using MDCK cells (Madin-Darby canine kidney cells), the epidemic strain of influenza A/Lipetsk/1V/2018 (H1N1 pdm09) (EPI_ISL_332798), the highly pathogenic avian influenza virus A/common gull/Saratov/1676/2018 (H5N6) strain (EPI_ISL_336925), and neutral red vital dye.

Results: The genomes of all studied strains contained determinants responsible for utilization of carbohydrates of plant origin; the genes of key enzymes for the synthesis of tryptophan and folic acid are present in the genomes of B. longum 379 and B. bifidum 791. A feature of the B. bifidum 791 genome is the presence of determinants responsible for the synthesis of thermostable type I bacteriocins - flavucin and lasso peptide. The B. bifidum 791 strain was found to show pronounced antiviral activity against both the strains of influenza A, the supernatant of which suppressed viral replication in vitro up to a dilution of 1:8, and the cells inhibited viral reproduction up to a concentration of 6·106 CFU/ml.

Conclusion: The analysis of complete genomes of B. longum 379, B. bifidum 1, and B. bifidum 791 showed features that determine their strain-specific properties, the findings on which were previously made empirically based on indirect signs. In the genomes of B. longum 379 and B. bifidum 791 strains, in contrast to B. bifidum 1 strain, key enzymes for the synthesis of tryptophan and folic acid were found. These substances have an impact on the human body in many ways, including having a thymoleptic effect (reducing emotional stress, irritability, anxiety, eliminating lethargy, apathy, melancholy, anxiety) and regulating cognitive activity. The presence of determinants responsible for the synthesis of thermostable type I bacteriocins in the genome of B. bifidum 791 strain determines its pronounced antiviral activity.

The aim of the study was to develop a diagnostic method for the quantitative determination of the main components of cartilage tissue of various types based on multivariate IR spectral analysis and verification of data using classical chemical analysis.

Materials and methods: Cartilages of the nasal septum, knee joint, rib, and nucleus pulposus of the intervertebral disc, as well as trypsinized and defective cartilage samples, were examined as samples. The IR spectra of the cartilage samples, as well as calibration mixtures of collagen and chondroitin sulfate, were obtained. The IR spectra were collected using the attenuated total reflectance techniques, and their processing was performed using the TQ Analyst software and the principal component regression calibration technique. Based on calibration dependence, the K_sp coefficient was determined as the ratio of the mass fractions of collagen and chondroitin sulfate. Its value was compared with the value of K_chem, equal to the ratio of the mass fractions of collagen and chondroitin sulfate, obtained using the classical chemical analysis of these substances.

Results: The IR spectra of cartilage tissues are a superposition of the IR spectra of collagen and chondroitin sulfate and qualitatively reflect their composition. A change in the ratio between the relative intensities of the characteristic bands of compounds in the IR spectrum is obvious only with a significant change in the content of these compounds in cartilage. This change occurs after trypsinization, when K_sp increases from 0.88±0.05 (K_chem~0.8) to 4.55. The use of a calibration model with a complete analysis of the cartilage IR spectrum made it possible to determine the difference in the ratio of the main components in the matrix of different samples in the absence of obvious changes in the IR spectra. Thus, a statistically significant decrease in the content of chondroitin sulfate in degraded articular cartilage (K_sp=4.4±1.8; K_chem~5.5) was shown compared with intact samples (K_sp=2.8±1.1; K_chem~2.6).

Conclusion: IR spectrometric express analysis of cartilage tissue employing the principal component regression method allows a correct determination of the ratio of the main components in the cartilage matrix, those of collagen and glycosaminoglycans. The proposed technique includes one measurement, does not require prolonged and laborious sample preparation, does not require long, multi-stage and laborious chemical manipulations to determine each of the components, and makes it possible to determine the features and changes in the composition for a large set of samples of cartilage tissue of different types. In future, this approach can be used for non-invasive diagnostics of cartilage tissue.

The aim of the study was to evaluate the use of barophoresis for the delivery of liquid-air drug substances to the gums using a mathematical model of the interaction of the drug mixture with periodontal tissues.

Materials and methods: The solution to the problem was preceded by generation of a geometric CAD model of the device and nozzle for barophoresis, including the nozzle and injector geometry. The Ansys SpaceClaim software package was used to generate the CAD geometry.

Results: When solving the problem of finding the optimal distance from the nozzle to the gum surface, the numerical modeling showed that at a distance of 5 mm, the volume fraction of liquid in the mixture is 18-20%. The mixture actually breaks through the gum, filling 0.8 mm of the gum thickness and spreading symmetrically to the sides at a distance of up to 3 cm, forming a cavity. At a distance of 10 mm from the nozzle to the gum surface, the liquid volume fraction in the mixture close to the gum lies in a narrow range of values of 5 to 7%. The mixture touches the surface of the gums, penetrating slightly - at a distance of 0.30-0.45 mm. At a distance of 15 mm from the nozzle to the gum surface, the volume fraction of liquid in the mixture near the gum lies in the range of 2-5%. The mixture slightly touches the gum surface, getting inside at a distance of up to 0.2 mm, having practically no effect on the gum.

Conclusion: The developed mathematical model confirmed the feasibility of application of barophoresis in the treatment of chronic generalized periodontitis. The optimal distance from the nozzle to the surface should be considered to be 10-15 mm. This distance is safe and allows the drug delivery to a depth of 0.45 mm.

The aim of the study was to compare various methods used for the bone reconstruction in the anterior wall of the maxillary sinus during sinus lift surgery; in addition, we aimed to study the effect of maxillary sinus membrane perforation on the healing process.

Materials and methods: The experiments were carried out using the North Caucasian sheep. Maxillary sinus lift surgery was performed on the animals under general anesthesia. The skin and muscle fascia were dissected layer-by-layer providing the optimal conditions for bone preparation; then, three bone windows were made on each side of the head. Two windows were sawn out with a spherical bur, the third window - with a hollow bur and part of the anterior wall was taken out. On one side, the mucous membrane of the maxillary sinus was pulled and perforated; on the other side, the sinus lift was performed with no membrane perforation. On each side, one window was left uncovered, the second was closed with a collagen membrane, and the third was closed with a bone cover. After 30 and 60 days, the sheep were taken out of the experiment in groups of three; samples were collected from the operated areas and examined using computed microtomography and histology.

Results: According to the histological study, the bone repair process developed normally regardless of the surgery technique. The process started with the appearance of granulation tissue and connective tissue cords; in the final stages, cellular differentiation, pronounced osteoblastic activity, and inter-beam formation were seen.The most active regeneration was observed in the areas where the bone defects were closed with a collagen membrane, and especially in the windows made with no perforation of the maxillary sinus membrane. The microtomographic and histological tests proved that perforation of the mucous membrane during the sinus lift operation impaired bone tissue regeneration.

Conclusion: The obtained results suggest that the most promising way to close a bone defect in the anterior wall of the maxillary sinus is the use of a collagen membrane; therefore, we recommend choosing this approach for sinus lift surgery.

The aim of the study was to explore the association between sudden cardiac death (SCD) and single nucleotide polymorphisms (SNPs) rs34554140, rs6670279, and rs6874185 from the list of potential molecular genetic markers of SCD, obtained in our earlier genome-wide allelotyping on pooled DNA samples.

Materials and methods: The study is based on the case-control principle. The SCD group included 438 deceased residents of Novosibirsk (average age - 53.2±9.1 years; men - 72.7%, women - 28.3%) with the main postmortem diagnoses of acute circulatory failure or acute coronary failure, which met the criteria of SCD established by the European Society of Cardiology. The control group included 435 live subjects enrolled in the international projects HAPIEE and MONICA (average age - 53.2±8.9 years; men - 70.0%, women - 30.0%). DNA was isolated by phenol-chloroform extraction from the myocardial tissue in the SCD group and from the venous blood in the control group. Genotyping was performed by polymerase chain reaction with subsequent analysis of restriction fragment length polymorphism in a polyacrylamide gel.

Results: The frequencies of the genotypes of SNPs rs34554140, rs6670279, and rs6874185 in the control group correspond to those predicted by the Hardy-Weinberg equilibrium (c²=0.98, 0.009, 3.39, respectively). The AA genotype of rs34554140 is associated with an increased risk of SCD (p=0.002; OR=1.85; 95% CI 1.26-2.71). The AT genotype has a protective effect against SCD (p=0.001; OR=0.53; 95% CI 0.36-0.78). In subgroups separated by gender and age, the differences persist in the subgroups of men, women, and individuals under 50 years old (p<0.05). The AA genotype of rs6670279 is associated with an increased risk of SCD (p=0.005; OR=1.54; 95% CI 1.15-2.06). The AT genotype has a protective effect against SCD (p=0.047; OR=0.73; 95% CI 0.54-0.98). When distributed by sex and age, the differences persist in the subgroups of men, individuals above 50 years old, and men above 50 years old (p<0.05). There were no significant differences in the frequencies of genotypes and alleles of rs6874185 between the SCD and control groups, even after the subgroups specified by gender and age were compared (p>0.05).

Conclusion: The association of single nucleotide polymorphisms rs34554140 and rs6670279 with SCD was confirmed. In contrast, no association of rs6874185 with SCD was detected.