Investigation of effect of fullerenol on viscoelasticity properties of human hepatocellular carcinoma by AFM-Based creep tests

Cellular elasticity is frequently measured to investigate the biomechanical effects of drug treatment, diseases and aging. In light of cellular viscosity property exhibited by filament actin networks, this study investigates the viscoelasticity alterations of human hepatocellular carcinoma (SMMC-7721) cell subjected to fullerenol treatment by means of creep tests realized by AFM indentation. An SMMC-7721 cell was first modeled as a sphere and then a flattened layer with finite thickness. Both Sneddon’s solutions and Dimitriadis model have been modified to adapt for viscoelastic situation, which are used to fit the same indentation depth – time curves obtained by creep tests. We find that the SMMC-7721 cell’s creep behavior is well described by the two modified models, and the divergence of parameters determined by the two models is justified. By fullerenol treatment, the SMMC-7721 cell exhibits a significant decrease of elastic modulus and viscosity, which is presumably due to the disruption of actin filaments. This work represents a new attempt to understand the alternation of the viscoelastic properties of cancerous cells under the treatment of fullerenol, which has the significance of comprehensively elucidating the biomechanical effects of anticancer agents (such as fullerenol) on cancer cells

Effect of surface adhesion in contact : application of Johnson-Kendall-Roberts model of nanoindentation

Finally this work studied the effect of surface adhesion on the mechanical behavior of two soft materials (two kinds of biological cells) subjected to atomic force microscope (AFM) indentation, i.e. pancreatic MIN6 cell and hepatocellular carcinoma which were treated by calcimimetic R568 and fullerenol respectively. They were also indented by different AFM probes: MIN6 cell by spherical indenter, and cancer cell by Vickers indenter. First of all, surface adhesion was manifested by the negative value of indentation force. For MIN6 cells，both JKR and finite element method are used to fit the force-displacement curve obtained by AFM indentation. For hepatocellular carcinoma, the JKR model is adapted for the Vickers indenter, and the “adapted” JKR model is used to fit the force-displacement curve. The results showed that JKR model can best describe the unloading force-displacement behaviors of the indentation curves, where a new parameter, termed work of adhesion in addition to Young’s modulus was extracted. Moreover, the difference between two biological cells and their treated counterparts were detected in terms of the magnitudes of the extracted parameters, i.e. Young’s modulus and work of adhesion. This implies that the study on the surface adhesion has potential significance in terms of medical diagnostics. The main contributions from the present research could be summarized as follows: i. For hard materials, this study presents a systematic investigation on the effect of surface adhesion on the shakedown behavior of two hardening materials, i.e. isotropic and kinematic hardening. The simulative results show that surface adhesion alone can initiate plastic deformation. In non-adhesive repeated contact, only elastic shakedown can occur while in adhesive repeated contact, plastic shakedown can occur, which indicate that surface adhesion force can alter the mechanical response of substrate material subjected to repetitive indentation. ii. For soft materials, this work uses JKR model to fit the force-displacement curve, yielding a new parameter, i.e. work of adhesion, in addition to Young’s modulus. In comparison to the Hertzian contact model, the JKR model provides obviously better fitting to the experimental results, indicating that the adhesion is significant in the cell interaction. Moreover, the difference between various biological cells could be characterized by the magnitude of work of adhesion, which implies that this parameter may also serve medical diagnostics

Axisymmetric contact problem for a flattened cell : contributions of substrate effect and cell thickness to the determination of viscoelastic properties by using AFM indentation

Nanoindentation technology has proven an effective method to investigate the viscoelastic properties of biological cells. The experimental data obtained by nanoindentation are frequently interpreted by Hertz contact model. However, in order to facilitate the application of Hertz contact model, a mass of studies assume cells have infinite thickness which does not necessarily represent the real situation. In this study, a rigorous contact model based upon linear elasticity is developed for the interpretation of indentation tests of flattened cells which represent a factual morphology. The cell, normally bonded to the petri dish, is initially treated as an elastic layer of finite thickness perfectly fixed to a rigid substrate, and the conic indenter is assumed to be frictionless. The theory of linear elasticity is utilized to solve this contact issue and then the solutions are extended to viscoelastic situation which is regarded as a good indicator for mechanical properties of biological cells. To test the present model, an AFM-based creep test has been conducted on living human hepatocellular carcinoma cell (SMMC-7721 cell) and its fullerenol-treated counterpart. The results indicate that the present model could not only describe very well the creep behavior of SMMC-7721 cells, but can also curb overestimation of the mechanical properties due to substrate effect. Moreover, the present model could identify the difference between the control and treated SMMC-7721 cells in terms of the extracted viscoelastic parameters, suggesting its potential in revealing the biomechanical effects of fullerenol-like drug treatment on cancerous cells

Investigation of work of adhesion of biological cell (human hepatocellular carcinoma) by AFM nanoindentation

In this study, we presented an investigation of mechanical properties by AFM nanoindentation on human hepatocellular carcinoma cells treated with fullerenol for 24, 48 and 72 hours. AFM nanoindentation was routinely applied to investigate the morphology and biomechanical properties of living carcinoma cells, and adhesion phenomena (negative force) were detected in the obtained force-displacement curves. Conventionally, Hertz contact model has been widely used for determination of cell elasticity, however this contact model cannot account for adhesion. Alternatively, JKR contact model, as expected for adhesion circumstance, has been applied to fit the obtained force-displacement curves. In this investigation, we have derived both the work of adhesion and the elastic modulus of biological cells (human hepatocellular carcinoma) under fullerenol treatment. The results show that the chosen JKR model can provide better fitting results than Hertz contact model. The results show that both Young’s modulus and work of adhesion exhibit significant variation as the treatment time increases. The calculated mechanical properties of elastic modulus and work of adhesion can be used as an effective bio-index to evaluate the effects of fullerenol or other anticancer agents on cancer cells and thus to provide insight into cancer progression in the treatment

Determination of work of adhesion of biological cell under AFM bead indentation

Hertz contact theory has been widely used for the determination of cell elasticity based on AFM indentation experiments. In light of the adhesive contact between AFM tip and cell, this study applied Johnson–Kendall–Roberts (JKR) model to fit the indentation force–displacement (F–D) curves reported previously. A MIN6 cell has been modeled as first a sphere and then a flattened cell with different thicknesses. The results have shown that both basic JKR model and “generalized” JKR model can best describe the unloading force–displacement behaviors of the indentation curves. The Young׳s modulus of the cell and the work of adhesion of the cell–indenter interface are obtained. In comparison to the Hertzian contact model, the JKR model provides obviously better fitting to the experimental results, indicating that the adhesion is significant in the cell interaction

Manifold Learning Side-Channel Attacks against Masked Cryptographic Implementations

Masking, as a common countermeasure, has been widely utilized to protect cryptographic implementations against power side-channel attacks. It significantly enhances the difficulty of attacks, as the sensitive intermediate values are randomly partitioned into multiple parts and executed on different times. The adversary must amalgamate information across diverse time samples before launching an attack, which is generally accomplished by feature extraction (e.g., Points-Of-Interest (POIs) combination and dimensionality reduction). However, traditional POIs combination methods, machine learning and deep learning techniques are often too time consuming, and necessitate a significant amount of computational resources. In this paper, we undertake the first study on manifold learning and their applications against masked cryptographic implementations. The leaked information, which manifests as the manifold of high-dimensional power traces, is mapped into a low-dimensional space and achieves feature extraction through manifold learning techniques like ISOMAP, Locally Linear Embedding (LLE), and Laplacian Eigenmaps (LE). Moreover, to reduce the complexity, we further construct explicit polynomial mappings for manifold learning to facilitate the dimensionality reduction. Compared to the classical machine learning and deep learning techniques, our schemes built from manifold learning techniques are faster, unsupervised, and only require very simple parameter tuning. Their effectiveness has been fully validated by our detailed experiments

The relationship between fear of missing out and mobile phone addiction among college students: the mediating role of depression and the moderating role of loneliness

BackgroundMobile phone addiction has adverse influences on the physical and mental health of college students. However, few studies shed light on the effect of fear of missing out on mobile phone addiction and the underlying mechanisms among college students.MethodsTo explore their associations, the present study used the Fear of Missing Out Scales (FoMOS), Loneliness Scale (USL-8), Mobile Phone Addiction Index Scale (MPAI), and Depression-Anxiety-Stress Questionnaire (DASS-21) to investigate 750 college students.ResultsThe results suggested that fear of missing out significantly positively predicted mobile phone addiction. This direct effect could be mediated by depression, and the indirect effect of fear of missing out on mobile phone addiction could be moderated by loneliness. Specifically, the indirect effect was stronger for students with high levels of loneliness.ConclusionThis study provides a theoretical basis for developing future interventions for mobile phone addiction in higher education students

Predictive value of PIMREG in the prognosis and response to immune checkpoint blockade of glioma patients

Glioma is the most common primary brain tumor in the human brain. The present study was designed to explore the expression of PIMREG in glioma and its relevance to the clinicopathological features and prognosis of glioma patients. The correlations of PIMREG with the infiltrating levels of immune cells and its relevance to the response to immunotherapy were also investigated. PIMREG expression in glioma was analyzed based on the GEO, TCGA, and HPA databases. Kaplan–Meier survival analysis was used to examine the predictive value of PIMREG for the prognosis of patients with glioma. The correlation between the infiltrating levels of immune cells in glioma and PIMREG was analyzed using the CIBERSORT algorithm and TIMRE database. The correlation between PIMREG and immune checkpoints and its correlation with the patients’ responses to immunotherapy were analyzed using R software and the GEPIA dataset. Cell experiments were conducted to verify the action of PIMREG in glioma cell migration and invasion. We found that PIMREG expression was upregulated in gliomas and positively associated with WHO grade. High PIMREG expression was correlated with poor prognosis of LGG, prognosis of all WHO grade gliomas, and prognosis of recurrent gliomas. PIMREG was related to the infiltration of several immune cell types, such as M1 and M2 macrophages, monocytes and CD8+ T cells. Moreover, PIMREG was correlated with immune checkpoints in glioma and correlated with patients’ responses to immunotherapy. KEGG pathway enrichment and GO functional analysis illustrated that PIMREG was related to multiple tumor- and immune-related pathways. In conclusion, PIMREG overexpression in gliomas is associated with poor prognosis of patients with glioma and is related to immune cell infiltrates and the responses to immunotherapy

Transmembrane and coiled-coil domains 3 is a diagnostic biomarker for predicting immune checkpoint blockade efficacy in hepatocellular carcinoma

Liver hepatocellular carcinoma (LIHC) is a malignancy with a high mortality and morbidity rate worldwide. However, the pathogenesis of LIHC has still not been thoroughly studied. Transmembrane and coiled-coil domains 3 (TMCO3) encodes a monovalent cation, a member of the proton transducer 2 (CPA2) family of transporter proteins. In the present study, TMCO3 expression and its relationship with cancer prognosis, as well as its immunological role in LIHC were studied by bioinformatic analysis. We found the significant overexpression of TMCO3 in LIHC in the TCGA, HCCDB, and GEO databases. In LIHC patients, high TMCO3 expression was related to poorer overall survival (OS) and TMCO3 had good predictive accuracy for prognosis. Moreover, TMCO3 was linked to the infiltrates of certain immune cells in LIHC. The correlation of TMCO3 with immune checkpoints was also revealed. Moreover, patients with LIHC with low TMCO3 expression showed a better response to immune checkpoint blockade (ICB) than those with LIHC with high TMCO3 expression. GO and KEGG enrichment analyses indicated that TMCO3 was probably involved in the microtubule cytoskeleton organization involved in mitosis, small GTPase mediated signal transduction, and TGF-β pathway. In conclusion, TMCO3 may be a potential biomarker for LIHC prognosis and immunotherapy