[Clinical importance of evaluation of circulating miRNA expression and epicardial adipose tissue thickness as predictors of cardiovascular pathology in young patients with type 1 diabetes mellitus]

Cardiovascular disease (CVD) in type 1 diabetes mellitus (T1DM) is preceded by asymptomatic changes in the geometry of the heart. The only symptoms of the beginning of cardiac remodeling and concomitant predictors of an unfavorable cardiovascular prognosis are: thickening of epicardial fat (EAT), secreting a number of adipokines, and cardiospecific miRNAs. To improve the effectiveness of prevention of CVD in young patients with DM1, a search was made for structural-functional and epigenetic markers.

AIM

To assess the state of the cardiovascular system according to MRI-heart with T1 mapping in T1DM without CVD. To reveal the relationship of epigenetic markers (circulating miR-126-5p, miR-21-5p) and adipokines with cardiovascular system in T1DM. Suggested personalized approach to patients with T1DM with initial manifestations of joint remodeling and/or exclusion of cardiospecific microRNA.

MATERIALS AND METHODS

The study included 40 patients: 30 with T1DM (age 26.2±7.4 years), 10 without T1DM (26.4±8.2). The patients underwent a general clinical examination, bioimpedancemetry, electrocardiography, MRI of the heart with T1 mapping, determination of adiponectin, resistin, visfatin, NT-proBNP, miR-126-5p, miR-21-5p.

RESULTS

Patients with T1DM had lower levels of cardioprotective miR-126-5p (p=0.046). According to MRI of the heart in T1DM, signs of vascular remodeling were revealed - thickening of the interventricular septum (p=0.001), posterior wall (p=0.012) and relative size of the walls (p=0.048) of the left ventricle, an increase in EAT density (p=0.001). Diffuse vascular fibrosis was found in 16% of patients from the T1DM group. Also, in T1DM, the expression of visfatin is increased (p=0.036) and adiponectin is reduced (p=0.043).

CONCLUSION

Structural and functional changes in the cardiovascular system (including thickening of the EAT), shifts in miR-126-5p expression and adipokines profile are observed already at a young age in patients with T1DM. In T1DM, diffuse vascular fibrosis is detected in 16% of patients. The data obtained were used to identify the group increased risk of developing CVD in T1DM and served as the basis for determining the timing of the start of preventive therapy.

Miniature Noninvasive Sensor Based on Impedance-Change Detection in Branches for Measuring Branch Ice Content in Overwintering Woody Plants

Advancements in detection instruments have enabled the real-time acquisition of water information during plant growth; however, the real-time monitoring of freeze-thaw information during plant overwintering remains a challenge. Based on the relationship between the change in the water-ice ratio and branch impedance during freezing, a miniature noninvasive branch volume ice content (BVIC) sensor was developed for monitoring real-time changes in volumetric ice content and the ice freeze-thaw rate of woody plant branches during the overwintering period. The results of the performance analysis of the impedance measurement circuit show that the circuit has a lateral sensitivity range, measurement range, resolution, measurement accuracy, and power consumption of 0-35 mm, 0-100%, 0.05%, ±1.76%, and 0.25 W, respectively. The dynamic response time was 0.296 s. The maximum allowable error by the output voltage fluctuation, owing to the ambient temperature and humidity, was only ±0.635%, which meets the actual use requirements. The calibration curve fit coefficients were >0.98, indicating a significant correlation. The ice content of plant branches under cold stress was measured for indoor and field environments, and the sensors could effectively monitor changes in the branch ice content in plants exposed to cold stress. Additionally, they can differentiate between plants with different cold resistances, indicating the reliability of the BVIC sensor.

Measurement of the frequency dependence of four terminal-pair air capacitors with a vector network analyzer

Four terminal-pair air capacitors are important transfer standards to calibrate LCR meters up to a frequency of 10 MHz. We report a simple and new method to obtain the frequency dependence of the four terminal-pair capacitance of these standards using a four-channel vector network analyzer (VNA). The frequency dependence of the capacitance of an air capacitor and its uncertainty can be obtained from a single set of measurements without changing connections between the standard and the VNA, as has been the case in previously published work. The calculation of the frequency dependency is straightforward and model-independent. Nevertheless, an elementary model is provided to explain the observed frequency dependence. This article allows every laboratory with a four-channel VNA to measure the frequency dependence of these capacitors. Hence, a significant shortening of the traceability chain is achieved.

A Low-Cost Handheld Impedimetric Biosensing System for Rapid Diagnostics of SARS-CoV-2 Infections

Current laboratory diagnostic approaches for virus detection give reliable results, but they require a lengthy procedure, trained personnel, and expensive equipment and reagents; hence, they are not a suitable choice for home monitoring purposes. This paper addresses this challenge by developing a portable impedimetric biosensing system for the identification of COVID-19 patients. This sensing system has two main parts: a throwaway two-working electrode (2-WE) strip and a novel read-out circuit, specifically designed for simultaneous signal acquisition from both working electrodes. Highly reliable electrochemical signal tracking from multiplex immunosensors provides a potential for flexible and portable multi-biomarker detection. The electrodes' surfaces were functionalized with SARS-CoV-2 Nucleocapsid Antibody enabling the selective detection of Nucleocapsid protein (N-protein) along with self-validation in the clinical nasopharyngeal swab specimens. The proposed programmable highly sensitive impedance read-out system allows for a wide dynamic detection range, which makes the sensor capable of detecting N-protein concentrations between 0.116 and 10,000 pg/mL. This lightweight and economical read-out arrangement is an ideal prospect for being mass-produced, especially during urgent pandemic situations. Also, such an impedimetric sensing platform has the potential to be redesigned for targeting not only other infectious diseases but also other critical disorders.

[Methods for assessing the electrophysical properties of body tissues and the possibility of their application in forensic medical practice]

This article provides an overview of some diagnostic methods for indicators and changes in the electrophysical properties of biological tissues. The key principles of assessing the electrical conductivity and resistance of tissues under the influence of alternating and direct current electric charge using standard and modified meters and signal generators, as well as the possibilities of digital improvement of computational models, are considered. Some existing and promising methods are presented that enable to solve important problems of forensic medical practice by registering changes in electrophysical parameters.

On the Effectiveness of Impedance-Based Fingerprint Presentation Attack Detection

Within the last few decades, the need for subject authentication has grown steadily, and biometric recognition technology has been established as a reliable alternative to passwords and tokens, offering automatic decisions. However, as unsupervised processes, biometric systems are vulnerable to presentation attacks targeting the capture devices, where presentation attack instruments (PAI) instead of bona fide characteristics are presented. Due to the capture devices being exposed to the public, any person could potentially execute such attacks. In this work, a fingerprint capture device based on thin film transistor (TFT) technology has been modified to additionally acquire the impedances of the presented fingers. Since the conductance of human skin differs from artificial PAIs, those impedance values were used to train a presentation attack detection (PAD) algorithm. Based on a dataset comprising 42 different PAI species, the results showed remarkable performance in detecting most attack presentations with an APCER = 2.89% in a user-friendly scenario specified by a BPCER = 0.2%. However, additional experiments utilising unknown attacks revealed a weakness towards particular PAI species.

Numerical simulation of deformable particles in a Coulter counter

In Coulter counters, cells counting and volumetry are achieved by monitoring their electrical print when they flow through a sensing zone. However, the volume measurement may be impaired by the cell dynamics, which may be difficult to control. In this paper, numerical simulations of the dynamics and electrical signature of red blood cells in a Coulter counter are presented, accounting for the deformability of the cells. In particular, a specific numerical pipeline is developed to overcome the challenge of the multi-scale nature of the problem. It consists in segmenting the whole computation of the cell dynamics and electrical response in a series of dedicated computations, with a saving of one order of magnitude in computational time. This numerical pipeline is used with rigid spheres and deformable red blood cells in an industrial Coulter counter geometry, and compared with experimental measurements. The simulations not only reproduce electrical signatures typical of those measured experimentally, but also allow an analysis of the electrical signature in terms of the heterogeneity of the electrical field and dynamics of the particles in the measurement zone. This study provides a methodology for computing the sizing of rigid or deformable particles by Coulter counters, opening the way to a better understanding of cells signatures in such devices.

An Aptamer-Based Capacitive Sensing Platform for Specific Detection of Lung Carcinoma Cells in the Microfluidic Chip

Improvement of methods for reliable and early diagnosis of the cellular diseases is necessary. A biological selectivity probe, such as an aptamer, is one of the candidate recognition layers that can be used to detect important biomolecules. Lung cancer is currently a typical cause of cancer-related deaths. In this work, an electrical sensing platform is built based on amine-terminated aptamer modified-gold electrodes for the specific, label-free detection of a human lung carcinoma cell line (A549). The microdevice, that includes a coplanar electrodes configuration and a simple microfluidic channel on a glass substrate, is fabricated using standard photolithography and cast molding techniques. A procedure of self-assembly onto the gold surface is proposed. Optical microscope observations and electrical impedance spectroscopy measurements confirm that the fabricated microchip can specifically and effectively identify A549 cells. In the experiments, the capacitance element that is dominant in the change of the impedance is calculated at the appropriate frequency for evaluation of the sensitivity of the biosensor. Therefore, a simple, inexpensive, biocompatible, and selective biosensor that has the potential to detect early-stage lung cancer would be developed.

Functionalized Thick Film Impedance Sensors for Use in In Vitro Cell Culture

Multi-electrode arrays find application in electrophysiological recordings. The quality of the captured signals depends on the interfacial contact between electrogenic cells and the electronic system. Therefore, it requires reliable low-impedance electrodes. Low-temperature cofired ceramic technology offers a suitable platform for rapid prototyping of biological reactors and can provide both stable fluid supply and integrated bio-hardware interfaces for recordings in electrogenic cell cultures. The 3D assembly of thick film gold electrodes in in vitro bio-reactors has been demonstrated for neuronal recordings. However, especially when dimensions become small, their performance varies strongly. This work investigates the influence of different coatings on thick film gold electrodes with regard to their influence on impedance behavior. PEDOT:PSS layer, titanium oxynitride and laminin coatings are deposited on LTCC gold electrodes using different 2D and 3D MEA chip designs. Their impedance characteristics are compared and discussed. Titanium oxynitride layers emerged as suitable functionalization. Small 86-µm-electrodes have a serial resistance R_s of 32 kOhm and serial capacitance C_s of 4.1 pF at 1 kHz. Thick film gold electrodes with such coatings are thus qualified for signal recording in 3-dimensional in vitro cell cultures.

1024-Pixel CMOS Multimodality Joint Cellular Sensor/Stimulator Array for Real-Time Holistic Cellular Characterization and Cell-Based Drug Screening

This paper presents a fully integrated CMOS multimodality joint sensor/stimulator array with 1024 pixels for real-time holistic cellular characterization and drug screening. The proposed system consists of four pixel groups and four parallel signal-conditioning blocks. Every pixel group contains 16 × 16 pixels, and each pixel includes one gold-plated electrode, four photodiodes, and in-pixel circuits, within a pixel footprint. Each pixel supports real-time extracellular potential recording, optical detection, charge-balanced biphasic current stimulation, and cellular impedance measurement for the same cellular sample. The proposed system is fabricated in a standard 130-nm CMOS process. Rat cardiomyocytes are successfully cultured on-chip. Measured high-resolution optical opacity images, extracellular potential recordings, biphasic current stimulations, and cellular impedance images demonstrate the unique advantages of the system for holistic cell characterization and drug screening. Furthermore, this paper demonstrates the use of optical detection on the on-chip cultured cardiomyocytes to real-time track their cyclic beating pattern and beating rate.

Comparison of Sensitivity and Quantitation between Microbead Dielectrophoresis-Based DNA Detection and Real-Time PCR

In this study, we describe a microbead-based method using dielectrophoresis (DEP) for the fast detection of DNA amplified by polymerase chain reaction (PCR). This electrical method measures the change in impedance caused by DEP-trapped microbeads to which biotinylated target DNA molecules are chemically attached. Using this method, measurements can be obtained within 20 min. Currently, real-time PCR is among the most sensitive methods available for the detection of target DNA, and is often used in the diagnosis of infectious diseases. We therefore compared the quantitation and sensitivity achieved by our method to those achieved with real-time PCR. We found that the microbead DEP-based method exhibited the same detection limit as real-time PCR, although its quantitative detection range was slightly narrower at 10–10⁵ copies/reaction compared with 10–10⁷ copies/reaction for real-time PCR. Whereas real-time PCR requires expensive and complex instruments, as well as expertise in primer design and experimental principles, our novel method is simple to use, inexpensive, and rapid. This method could potentially detect viral and other DNAs efficiently in combination with conventional PCR.

A Versatile Bonding Method for PDMS and SU-8 and Its Application towards a Multifunctional Microfluidic Device

This paper reports a versatile and irreversible bonding method for poly(dimethylsiloxane) (PDMS) and SU-8. The method is based on epoxide opening and dehydration reactions between surface-modified PDMS and SU-8. A PDMS replica is first activated via the low-cost lab equipment, i.e., the oxygen plasma cleaner or the corona treater. Then both SU-8 and plasma-treated PDMS samples are functionalized using hydrolyzed (3-aminopropyl)triethoxysilane (APTES). Ultimately, the samples are simply brought into contact and heated to enable covalent bonding. The molecular coupling and chemical reactions behind the bonding occurring at the surfaces were characterized by water contact angle measurement and X-ray photoelectron spectroscopy (XPS) analysis. The reliability of bonded PDMS-SU-8 samples was examined by using tensile strength and leakage tests, which revealed a bonding strength of over 1.4 MPa. The presented bonding method was also applied to create a metal-SU-8-PDMS hybrid device, which integrated SU-8 microfluidic structures and microelectrodes. This hybrid system was used for the effective trapping of microparticles on-chip, and the selective releasing and identification of predefined trapped microparticles. The hybrid fabrication approach presented here, based on the PDMS-SU-8 bonding, enables multifunctional integration in complex microfluidic devices.

Visualized Multiprobe Electrical Impedance Measurements with STM Tips Using Shear Force Feedback Control

Here we devise a multiprobe electrical measurement system based on quartz tuning forks (QTFs) and metallic tips capable of having full 3D control over the position of the probes. The system is based on the use of bent tungsten tips that are placed in mechanical contact (glue-free solution) with a QTF sensor. Shear forces acting in the probe are measured to control the tip-sample distance in the Z direction. Moreover, the tilting of the tip allows the visualization of the experiment under the optical microscope, allowing the coordination of the probes in X and Y directions. Meanwhile, the metallic tips are connected to a current-voltage amplifier circuit to measure the currents and thus the impedance of the studied samples. We discuss here the different aspects that must be addressed when conducting these multiprobe experiments, such as the amplitude of oscillation, shear force distance control, and wire tilting. Different results obtained in the measurement of calibration samples and microparticles are presented. They demonstrate the feasibility of the system to measure the impedance of the samples with a full 3D control on the position of the nanotips.

Objective prediction of pharyngeal swallow dysfunction in dysphagia through artificial neural network modeling

BACKGROUND

Pharyngeal pressure-flow analysis (PFA) of high resolution impedance-manometry (HRIM) with calculation of the swallow risk index (SRI) can quantify swallow dysfunction predisposing to aspiration. We explored the potential use of artificial neural networks (ANN) to model the relationship between PFA swallow metrics and aspiration and to predict swallow dysfunction.

METHODS

Two hundred consecutive dysphagia patients referred for videofluoroscopy and HRIM were assessed. Presence of aspiration was scored and PFA software derived 13 metrics and the SRI. An ANN was created and optimized over training cycles to achieve optimal classification accuracy for matching inputs (PFA metrics) to output (presence of aspiration on videofluoroscopy). Application of the ANN returned a value between 0.00 and 1.00 reflecting the degree of swallow dysfunction.

KEY RESULTS

Twenty one patients were excluded due to insufficient number of swallows (<4). Of 179, 58 aspirated and 27 had aspiration pneumonia history. The SRI was higher in aspirators (aspiration 24 [9, 41] vs no aspiration 7 [2, 18], p < 0.001) and patients with pneumonia (pneumonia 27 [5, 42] vs no pneumonia 8 [3, 24], p < 0.05). The ANN Predicted Risk was higher in aspirators (aspiration 0.57 [0.38, 0.82] vs no aspiration 0.13 [0.4, 0.25], p < 0.001) and in patients with pneumonia (pneumonia 0.46 [0.18, 0.60] vs no pneumonia 0.18 [0.6, 0.49], p < 0.01). Prognostic value of the ANN was superior to the SRI.

CONCLUSIONS & INFERENCES

In a heterogeneous cohort of dysphagia patients, PFA with ANN modeling offers enhanced detection of clinically significant swallowing dysfunction, probably more accurately reflecting the complex interplay of swallow characteristics that causes aspiration.

Assessment of bolus transit with intraluminal impedance measurement in patients with esophageal motility disorders

BACKGROUND

The clinical management of patients with non-obstructive dysphagia is notoriously difficult. Esophageal impedance measurement can be used to measure esophageal bolus transit without the use of radiation exposure to patients. However, validation of measurement of bolus transit with impedance monitoring has only been performed in healthy subjects with normal motility and not in patients with dysphagia and esophageal motility disorders. The aim was, therefore, to investigate the relationship between transit of swallowed liquid boluses in healthy controls and in patients with dysphagia.

METHODS

Twenty healthy volunteers and 20 patients with dysphagia underwent concurrent impedance measurement and videofluoroscopy. Each subject swallowed five liquid barium boluses. The ability of detecting complete or incomplete bolus transit by means of impedance measurement was assessed, using radiographic bolus transit as the gold standard.

KEY RESULTS

Impedance monitoring recognized stasis and transit in 80.5% of the events correctly, with 83.9% of bolus transit being recognized and 77.2% of stasis being recognized correctly. In controls 79.8% of all swallows were scored correctly, whereas in patients 81.3% of all swallows were scored correctly. Depending on the contractility pattern, between 77.0% and 94.3% of the swallows were scored correctly.

CONCLUSIONS & INFERENCES

Impedance measurement can be used to assess bolus clearance patterns in healthy subjects, but can also be used to reliably assess bolus transit in patients with dysphagia and motility disorders.

Experimental verification of depolarization effects in bioelectrical impedance measurement

The electrode polarization effects on bioelectrical impedance measurement at low-frequency cannot be ignored. In this paper, the bioelectrical data of mice livers are measured to specify the polarization effects on the bio-impedance measurement data. We firstly introduce the measurement system and methodology. Using the depolarization method, the corrected results are obtained. Besides, the specific effects of electrode polarization on bio-impedance measurement results are investigated using comparative analysis of the previous and posterior correction results from dielectric spectroscopy, Cole-Cole plot, conductivity and spectroscopy of dissipation tangent. Experimental results show that electrode polarization has a significant influence on the characteristic parameters of mouse liver tissues. To be specific, we see a low-frequency limit resistance R0 increase by 19.29%, a reactance peak XP increase by 8.50%, a low-frequency limit conductivity Kl decrease by 17.65% and a dissipation peak tangent decrease by 160%.

Automated impedance manometry analysis as a method to assess esophageal function

BACKGROUND

Diagnostic evaluation of non-achalasia esophageal dysphagia remains challenging because of a lack of a clear relationship between symptoms, esophageal contraction patterns, and esophageal bolus flow. This study evaluates a novel approach to pressure-impedance analysis called automated impedance manometry (AIM) analysis in relation to bolus characteristics, Chicago classification metrics, bolus perception, and dysphagia.

METHODS

AIM analysis was performed on esophageal high resolution manometry-impedance recordings from 12 healthy controls and 15 patients with dysphagia. In each subject, 10 liquid, 10 semisolid, and 10 solid swallows were analyzed using AIMplot software.

KEY RESULTS

This study demonstrated that (i) esophageal pressure-flow parameters differ with bolus type (liquid, semisolid, and solids), (ii) impedance at peak pressure parameter can discriminate normal from dysphagic subjects with high accuracy on a cut-off threshold at 2400 Ohms (kappa 0.77, sensitivity 0.83, and specificity 0.93), and (iii) nadir impedance and impedance at peak pressure highly correlate with perception of esophageal bolus flow (r = -0.65, p = 0.02; r = -0.70, p = 0.01 resp).

CONCLUSIONS & INFERENCES

This study presents novel esophageal pressure-flow variables in control subjects and in a cohort of patients with dysphagia. These variables are altered in relation to bolus consistency and can discriminate between subjects with and without symptoms of dysphagia. For the first time, we present high resolution esophageal pressure-flow variables that accurately link in with patient perception of esophageal bolus hold up.

Investigation of the liquid crystal alignment layer: effect on electrical properties

We investigate the electrical behavior of a symmetric liquid crystal (LC) cell: elecrode-silane-LC-silane-electrode. The silane (chlorodimethyloctadecyl-silane) layer induces a homeotropic orientation of the nematic liquid crystal (NLC) molecules. The wettability technique is used to detect the change of the surface energy of the electrode upon cleaning and silane layer deposition. We report on the dynamic impedance measurements of the nematic liquid crystal cell. It is found that the silane alignment layer has a blocking effect on the liquid crystal (LC) cell. We also study the relaxation behavior of the cell which is later assimilated as an electrical equivalent circuit.