Репозиторий Университета

© 2020 Elsevier Ltd The purpose of this study is the mechanical characterization of the mid-to- old-age human anterior lens capsules (ALCs) obtained by capsulorhexis using Atomic Force Microscopy (AFM) and a nanoindenter at different spatial scales. The dependencies on the human age, presence or absence of pseudoexfoliation syndrome (PEX), and application of trypan blue staining during the surgery were analyzed. The measurements on both the anterior (AS) and epithelial (ES) sides of the ALC were conducted and the effect of cells present on the epithelial side was carefully accounted for. The ES of the ALC had a homogenous distribution of the Young's modulus over the surface as shown by the macroscale mapping with the nanoindenter and local AFM indentations, while the AS was more heterogeneous. Age-related changes were assessed in groups ranging from the mid-age (from 48 years) to old-age (up to 93 years). We found that the ES was always stiffer than the AS, and this difference decreased with age due to a gradual decrease in the Young's modulus of the ES and an increase in the modulus of the AS. No significant changes were found in the mechanical properties of ALCs of PEX patients versus the PEX-free group, as well as in the properties of the ALC with and without trypan blue staining.

© 2019 Elsevier Ltd The lens capsule, a thin specialized basement membrane that encloses the crystalline lens, is essential for both the structural and biomechanical integrity of the lens. Knowing the mechanical properties of the lens capsule is important for understanding its physiological functioning, role in accommodation, age-related changes, and for providing a better treatment of a cataract. In this review, we have described the techniques used for the lens capsule biomechanical testing on the macro- and microscale and summarized the current knowledge about its mechanical properties.

© 2019 Elsevier Ltd The lens capsule, a thin specialized basement membrane that encloses the crystalline lens, is essential for both the structural and biomechanical integrity of the lens. Knowing the mechanical properties of the lens capsule is important for understanding its physiological functioning, role in accommodation, age-related changes, and for providing a better treatment of a cataract. In this review, we have described the techniques used for the lens capsule biomechanical testing on the macro- and microscale and summarized the current knowledge about its mechanical properties.

© 2019 Elsevier Ltd The lens capsule, a thin specialized basement membrane that encloses the crystalline lens, is essential for both the structural and biomechanical integrity of the lens. Knowing the mechanical properties of the lens capsule is important for understanding its physiological functioning, role in accommodation, age-related changes, and for providing a better treatment of a cataract. In this review, we have described the techniques used for the lens capsule biomechanical testing on the macro- and microscale and summarized the current knowledge about its mechanical properties.

© 2019 Elsevier Ltd The lens capsule, a thin specialized basement membrane that encloses the crystalline lens, is essential for both the structural and biomechanical integrity of the lens. Knowing the mechanical properties of the lens capsule is important for understanding its physiological functioning, role in accommodation, age-related changes, and for providing a better treatment of a cataract. In this review, we have described the techniques used for the lens capsule biomechanical testing on the macro- and microscale and summarized the current knowledge about its mechanical properties.

© 2019 Elsevier Ltd The lens capsule, a thin specialized basement membrane that encloses the crystalline lens, is essential for both the structural and biomechanical integrity of the lens. Knowing the mechanical properties of the lens capsule is important for understanding its physiological functioning, role in accommodation, age-related changes, and for providing a better treatment of a cataract. In this review, we have described the techniques used for the lens capsule biomechanical testing on the macro- and microscale and summarized the current knowledge about its mechanical properties.

© 2019 Wiley Periodicals, Inc. To date, a myriad of strategies has been suggested for targeting the chemical signaling of cancer cells. Also, biomechanical features are gaining much more attention. These features can be used as biomarkers which influence cancer progression. Current approaches on cancer treatment are mainly focused on changing the biochemical signaling of cancer cells, whereas less attention was devoted to their biomechanical properties. Herein, we propose targeting of cancer cell mechanics through the microenvironmental mechanical and chemical cues. As such, we examined the role of substrate stiffness as well as the effect of epidermal growth factor receptor (EGFR) blockade in the cell mechanics. As a mechanical stimulus, stiff and soft polydimethylsiloxane substrates were utilized, while as a chemical stimulus, EGFR blockade was considered. Thus, breast cancer cell lines, MCF7 and MDA-MB-231, were cultured among chemical and mechanical groups. The local elasticity of cancer cells was assessed by atomic force microscopy nanoindentation method. Furthermore, we evaluated the effect of mentioned mechanical and chemical treatments on the morphology, actin cytoskeleton structures, and cancer cell migration abilities. The stiffness and migration ability of cancer cells increased by substrate stiffening while Cetuximab treatment demonstrated an elevation in the elastic modulus of cells followed by a reduction in the migration ability. These findings indicate that cancer cell mechanics is modulated not only by the mechanical cues but also by the chemical ones through EGFR signaling pathway. Overall, our results illustrate that manipulation of cell mechanics allows for the possible modulation of tumor cell migration. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1569–1581, 2019.

© Microscopy Society of America 2018. Radiation therapy, widely used in the treatment of a variety of malignancies in the pelvic area, is associated with inevitable damage to the surrounding healthy tissues. We have applied atomic force microscopy (AFM) to track the early damaging effects of ionizing radiation on the collagen structures in the experimental animals' bladder and rectum. The first signs of the low-dose radiation (2 Gy) effect were detected by AFM as early as 1 week postirradiation. The observed changes were consistent with initial radiation destruction of the protein matrix. The alterations in the collagen fibers' packing 1 month postirradiation were indicative of the onset of fibrotic processes. The destructive effect of higher radiation doses was probed 1 day posttreatment. The severity of the radiation damage was proportional to the dose, from relatively minor changes in the collagen packing at 8 Gy to the growing collagen matrix destruction at higher doses and complete three-dimensional collagen network restructuring towards fibrotic-type architecture at the dose of 22 Gy. The AFM study appeared superior to the optical microscopy-based studies in its sensitivity to early radiation damage of tissues, providing valuable additional information on the onset and development of the collagen matrix destruction and remodeling.

AIM: To develop predictive model for hepatic insufficiency in obstructive jaundice.MATERIAL AND METHODS: Obstructive jaundice was modeled by the author's method on 48 mini pigs, while morpho-functional features of erythrocytes were studied by using of INTEGRA Aura atomic force microscope (NT-MDT, Zelenograd, Russia). Histological specimens were stained with hematoxylin and eosin. Discriminant analysis was used to create predictive model for hepatic insufficiency.RESULTS: Mathematical model of hepatic insufficiency prediction has been developed. Sensitivity and specificity of this model were 94.1% and 74.2% respectively. Total percentage of correct predictions was 81.3%.CONCLUSION: Severe obstructive jaundice contributes erythrocyte's transformation from biconcave to dome-shaped followed by changes of its physical properties. Erythrocyte's volume and activity of cytolysis enzymes are the most informative to predict hepatic insufficiency. Our model allows us to diagnose this complication at early stages and to correct pre-, intra- and postoperative therapy.

© 2018 Vitebsk State Medical University. All rights reserved. Objective: To study the functional activity and cytoarchitectonics of neutrophilic granulocytes by the atomic force microscopy technique in the patients with mechanical jaundice of benign genesis of varying severity. Methods: The subject of the study were 92 patients aged from 47 to 69 years undergoing the in-patient treatment in the surgical departments of medical institutions in Krasnoyarsk with the diagnosis of mechanical jaundice of benign genesis. The control group consisted of 60 donors, comparable in sex and age with the main group. Depending on the severity of mechanical jaundice, luminol-dependent chemiluminescence of neutrophils was investigated and atomic-force microscopy of neurophilic granulocytes was performed to determine the shape, membrane state, geometric dimensions and adhesion forces of the blood neutrophils. Results: In patients with mechanical jaundice, the intensity of spontaneous chemiluminescence depends on the severity of mechanical jaundice. The kinetics of the chemiluminescent response of the peripheral blood neutrophils indicates an increase in the compensatory functional capacity of this cell population in case of mild degree of mechanical jaundice severity with their depletion in parallel with the increase in the severity of mechanical jaundice. Atomic force microscopy revealed violations of the structural organization of the neutrophil granulocyte. With increasing severity of mechanical jaundice, neutrophil became convex in shape, the number of segments of the nucleus increased, the cell membrane became irregular, the neutrophil volume reached 62.20 + 5.94 m3. The magnitude of the adhesion forces of neutrophils decreased by 25% in patients with class B severity of mechanical jaundice and by 31% with class C severity of mechanical jaundice. Conclusions: Based on the analysis of the chemiluminescent activity of neutrophilic granulocytes and their cytoarchitectonics, we concluded that the functional capabilities of neutrophilic granulocytes in mechanical jaundice are depleted in parallel with the increase in the severity of mechanical jaundice. Dysfunctions of neutrophils in mechanical jaundice are caused by the change in its cytoarchitectonics and by the decrease in adhesion forces.

© 2018, Media Sfera. All rights reserved. The article describes a newly developed and tested diffractive optical element (DOE) that converts non-uniform radiation of the laser output into a homogeneous ring. The Gerchberg-Saxton algorithm is shown to be well suited for achieving annular intensity distribution. Testing this ring transducer on threshold-plasticity cornea demonstrated the reversibility of axisymmetric changes in the cornea. Atomic-Force microscopy of the area of maximum stresses in the corneal periphery showed no significant changes in the structure of the cornea when irradiated in the selected mode. Measurement of Young’s modulus of the corneal surface areas after their irradiation also revealed no changes in the elastic properties, while examination of the corneal structure demonstrated the absence of significant structural changes in irradiated samples compared with intact ones.

© 2018, Nizhny Novgorod State Medical Academy. All rights reserved. The aim of the study was to demonstrate a good diagnostic potential of atomic force microscopy (AFM) in tracking morphological changes in the extracellular matrix (ECM) of connective tissue due to pathological processes. Here we summarize our experience in AFM application in a number of biomedical studies on the connective tissue disease, both for the research and clinical purposes. Materials and Methods. Depending on the project application (experimental or clinical), the tissue specimens were harvested either from animals, or from patients in the course of their surgical treatment, or post mortem. AFM images of fixed tissue slices on glass slides were acquired with a Solver P47 AFM instrument (NT-MDT, Russia), in the semi-contact mode. For mechanical properties mapping, the images were acquired on air in the PeakForce Quantitative Nanomechanical Mapping mode (PeakForce QNM®), using a MultiMode 8 atomic force microscope (Bruker, USA). The regions of interest for scanning were selected in accordance with the histological assignments for the same sample, based on the view of a sample in the built-in optical microscope of the AFM instrument setup. To quantify the changes in the ECM morphology visualized by AFM imaging, we applied flicker-noise spectroscopy parameterization. Results. AFM has been shown to reveal visible deviations from the normal morphology of the ECM in diseased tissues. We found that AFM and related techniques are capable of tracking disease-related changes at different levels of collagen organization in the ECM. At the microscale, AFM may detect loosening and disorganization of collagen fibers (e.g., in a dysplastic process), or the opposite process of their packing into tight parallel bundles in a fibrotic process. AFM may also monitor the ratio between collagen and non-fibrous material of the ECM, for example, in inflammatory and neoplastic processes. At the level of collagen fibrils, AFM may reveal early signs of the matrix destruction and remodeling not visible at the microscopic level. The flicker-noise spectroscopy parameters provide quantification of the morphological changes visualized by AFM. The PeakForce QNM® and nanoindentation studies give a further insight into the state of ECM via tracking changes in the local mechanical and adhesive properties. All our AFM studies appeared in a good agreement with the histological findings and generally had a superior sensitivity to pathology-related ECM rearrangements. Conclusion. AFM may serve as a valuable complementary diagnostic tool for tracking pathological changes in the connective tissue.