Mechanism of action and side effects of colchicine based on biomechanical properties of cells.

Many diseases are related to changes in the biomechanical properties of cells; their study can provide a theoretical basis for drug screening and can explain the internal working of living cells. In this study, the biomechanical properties of nephrocytes (VERO cells), hepatocytes (HL-7702 cells), and hepatoma cells (SMCC-7721 cells) in culture were detected by atomic force microscopy (AFM) to analyse the side effects of colchicine at different concentrations (0.1 µg/mL (A) and 0.2 µg/mL (B)) at the nanoscale for 2, 4 and 6 h. Compared with the corresponding control cells, the damage to the treated cells increased in a dose-dependent manner. Among normal cells, the injury of nephrocytes (VERO cells) was markedly worse than that of hepatocytes (HL-7702 cells) in both colchicine solutions A and B. Based on the analyses of biomechanical properties, the colchicine solution reduced the rate of division and inhibited metastasis of SMCC-7721 cells. By comparing these two concentrations, we found that the anticancer effect of colchicine solution A was greater than that of solution B. Studying the mechanical properties of biological cells can help understand the mechanism of drug action at the molecular level and provide a theoretical basis for preventing the emergence and diagnosis of diseases at the nanoscale.

A Finite-Time Sliding-Mode Controller Based on the Disturbance Observer and Neural Network for Hysteretic Systems with Application in Piezoelectric Actuators.

Piezoelectric actuators (PEAs) have the benefits of a high-resolution and high-frequency response and are widely applied in the field of micro-/nano-high-precision positioning. However, PEAs undergo nonlinear hysteresis between input voltage and output displacement, owing to the properties of materials. In addition, the input frequency can also influence the hysteresis response of PEAs. Research on tracking the control of PEAs by using various adaptive controllers has been a hot topic. This paper presents a finite-time sliding-mode controller (SMC) based on the disturbance observer (DOB) and a radial basis function (RBF) neural network (NN) (RBF-NN). RBF-NN is used to replace the hysteresis model of the dynamic system, and a novel finite-time adaptive DOB is proposed to estimate the disturbances of the system. By using RBF-NN, it is no longer necessary to establish the hysteresis model. The proposed DOB does not rely on any priori knowledge of disturbances and has a simple structure. All the solutions of closed-loop systems are practical finite-time-stable, and tracking errors can converge to a small neighborhood of zero in a finite time. The proposed control method was compiled in C language in the VC++ environment. A series of comparative experiments were conducted on a platform of a commercial PEA to validate the method. According to the experimental results of the sinusoidal and triangular trajectories under the frequencies of 1, 50, 100, and 200 Hz, the proposed control method is feasible and effective in improving the tracking control accuracy of the PEA platform.

Laser Interference Additive Manufacturing: Mask Bundle Shape Bionic Shark Skin Structure.

Here, we explored a new manufacturing strategy that uses the mask laser interference additive manufacturing (MLIAM) technique, which combines the respective strengths of laser interference lithography and mask lithography to efficiently fabricate across-scales three-dimensional bionic shark skin structures with superhydrophobicity and adhesive reduction. The phenomena and mechanisms of the MLIAM curing process were revealed and analyzed, showing the feasibility and flexibility. In terms of structural performance, the adhesive force on the surface can be tuned based on the growth direction of the bionic shark skin structures, where the maximum rate of the adhesive reduction reaches about 65%. Furthermore, the evolution of the directional diffusion for the water droplet, which is based on the change of the contact angle, was clearly observed, and the mechanism was also discussed by the models. Moreover, no-loss transportations were achieved successfully using the gradient adhesive force and superhydrophobicity on the surface by tuning the growth direction and modifying by fluorinated silane. Finally, this work gives a strategy for fabricating across-scale structures on micro- and nanometers, which have potential application in bioengineering, diversional targeting, and condenser surface.

The comparative effects of sacubitril/valsartan versus enalapril on pulmonary hypertension due to heart failure with a reduced ejection fraction.

The purpose of this study was to investigate the effects of sacubitril/valsartan on right ventricular (RV) function in patients with pulmonary hypertension (PH) due to heart failure with reduced ejection fraction (HFrEF). We prospectively enrolled patients with HFrEF-induced PH admitted to the Department of Cardiology between August 2018 and December 2019. Patients were randomized to receive oral treatment with sacubitril/valsartan or enalapril. Epidemiological data were recorded before treatment. Echocardiography was performed at admission and 6 months of follow-up, and all parameters were compared. Major adverse cardiac events (MACEs) were compared between baseline and 6 months follow-up. There were no significant differences in the baseline characteristics between the two groups. After 6 months of treatment, both treatment groups improved the following parameters from baseline (mean ± SD): left atrium, left ventricle, the left ventricular ejection function (LVEF), RV systolic function (the tricuspid annular plane systolic excursion [TAPSE], the systolic pulmonary artery pressure [sPAP], and TAPSE/sPAP). After 6 months, sacubitril/valsartan improved significantly the following parameters compared with enalapril (all p < 0.05): LVEF (47.07 ± 6.93% vs. 43.47 ± 7.95%); TAPSE (15.33 ± 1.31 vs. 14.78 ± 1.36 mm); sPAP (36.76 ± 14.32 vs. 42.26 ± 12.07 mmHg); and TAPSE/sPAP ratio (0.50 ± 0.23 vs. 0.39 ± 0.14), respectively. There was no difference in readmissions due to recurrent heart failure. Sacubitril/valsartan seems to provide more beneficial effects among patients with HFrEF-induced PH to improve RV function, along with a decrease in pulmonary pressure.

Mechanobiology Analysis of Manifold Live Cells in Vitro with Atomic Force Acoustic Microscopy.

Mechanobiology analysis has been considered one of the important parameters to explore the physiological behavior inside cells. However, the morphology and mechanical characterization of live cells by employing atomic force acoustic microscopy (AFAM) has rarely been investigated to date. In this paper, the morphological and mechanical properties of five various live cells in vitro based on AFAM is detected for the first time. Combining AFAM with inverted optical microscopy and scanning electron microscopy (SEM), it has enabled the imaging of various live cells. According to the AFAM experimental results, the mechanical properties of live cells were obtained by fitting the force-depth curves with Hertz-Sneddon model. The conducted experiments and obtained results verified that it is viable to furnish insights into the multifunctional applicability of the AFAM-based characterization in mechanobiology, which has the advantages of making a contribution to diagnosing diseased cells.

Effect of AFM Nanoindentation Loading Rate on the Characterization of Mechanical Properties of Vascular Endothelial Cell.

Vascular endothelial cells form a barrier that blocks the delivery of drugs entering into brain tissue for central nervous system disease treatment. The mechanical responses of vascular endothelial cells play a key role in the progress of drugs passing through the blood-brain barrier. Although nanoindentation experiment by using AFM (Atomic Force Microscopy) has been widely used to investigate the mechanical properties of cells, the particular mechanism that determines the mechanical response of vascular endothelial cells is still poorly understood. In order to overcome this limitation, nanoindentation experiments were performed at different loading rates during the ramp stage to investigate the loading rate effect on the characterization of the mechanical properties of bEnd.3 cells (mouse brain endothelial cell line). Inverse finite element analysis was implemented to determine the mechanical properties of bEnd.3 cells. The loading rate effect appears to be more significant in short-term peak force than that in long-term force. A higher loading rate results in a larger value of elastic modulus of bEnd.3 cells, while some mechanical parameters show ambiguous regulation to the variation of indentation rate. This study provides new insights into the mechanical responses of vascular endothelial cells, which is important for a deeper understanding of the cell mechanobiological mechanism in the blood-brain barrier.

Determination of viscohyperelastic properties of tubule epithelial cells by an approach combined with AFM nanoindentation and finite element analysis.

Tubule epithelial cell is a complex element that not only exhibits elasticity behaviour, but also presents nonlinear and time-dependent behaviour during any stage of its life cycle. Responses of tubule epithelial cells to physical stimuli are influenced by their mechanical properties. However, accurately constitution of their mechanical properties is still a challenge and the characterisation mechanism is far from sophisticated. In addition, the particular mechanism that determines the mechanical response is still unclear. In order to overcome this limit, an approach combined with AFM nanoindentation experiment and computation modelling by a viscohyperelastic model is developed to describe the complex behaviour in the current study. Viscohyperelastic parameters of tubule epithelial cells treated and untreated with drug Cytochalasin D are obtained by the optimization algorithm applied in this approach. The comparison between treated and untreated results indicate that larger amount of relaxation was observed due to the disruption of cytoskeleton when using drug Cytochalasin D. Our results demonstrate the feasibility of this approach to monitor the variation of these viscohyperelastic parameters, which can be used as an effective index for renal disease diagnosed and drug evaluation.

Self-repair behaviour of the neuronal cell membrane by conductive atomic force indentation.

Conductive atomic force indentation (CAFI) was proposed to study the self-repair behaviour of the neuronal cell membrane here. CAFI was used to detect the changes of membrane potentials by performing the mechanical indentation on neurons with a conductive atomic force microscope. In the experiment, a special insulation treatment was made on the conductive probe, which turned out to be a conductive nanoelectrode, to implement the CAFI function. The mechanical properties of the neuronal cell membrane surface were tested and the membrane potential changes of neurons cultured in vitro were detected. The self-repair behaviour of the neuronal cell membrane after being punctured was investigated. The experiment results show that CAFI provides a new way for the study of self-repair behaviours of neuronal cell membranes and mechanical and electrical properties of living cells.

Research on the Effect of Electrical Signals on Growth of Sansevieria under Light-Emitting Diode (LED) Lighting Environment.

The plant electrical signal has some features, e.g. weak, low-frequency and time-varying. To detect changes in plant electrical signals, LED light source was used to create a controllable light environment in this study. The electrical signal data were collected from Sansevieria leaves under the different illumination conditions, and the data was analyzed in time domain, frequency domain and time-frequency domain, respectively. These analyses are helpful to explore the relationship between changes in the light environment and electrical signals in Sansevieria leaves. The changes in the plant electrical signal reflected the changes in the intensity of photosynthesis. In this study, we proposed a new method to express plant photosynthetic intensity as a function of the electrical signal. That is, the plant electrical signal can be used to describe the state of plant growth.

[Clinical evaluation of implant anchorage with segmental arch technique on the elongated teeth and tilted teeth].

PURPOSE: To evaluate the clinical efficiency of implant anchorage combined with segmental arch technique. METHODS: Segmental arch technique of the micro-implant and adjacent teeth was used, ideal space for the superstructure of the implant was gained. RESULTS: The implant anchorage with segmental arch technique methods decreased the therapeutic process efficiency and made enough space for superstructure of the implant. CONCLUSIONS: Implant anchorage with segmental arch technique can undertake the vertical anchorage force efficiently, depress the molar safely and make enough space for superstructure of implants.