Erythrocyte rouleau formation under polarized electromagnetic fields

Metabolite and protein shifts in mature erythrocyte under hypoxia

As the only cell type responsible for oxygen delivery, erythrocytes play a crucial role in supplying oxygen to hypoxic tissues, ensuring their normal functions. Hypoxia commonly occurs under physiological or pathological conditions, and understanding how erythrocytes adapt to hypoxia is fundamental for exploring the mechanisms of hypoxic diseases. Additionally, investigating acute and chronic mountain sickness caused by plateaus, which are naturally hypoxic environments, will aid in the study of hypoxic diseases. In recent years, increasingly developed proteomics and metabolomics technologies have become powerful tools for studying mature enucleated erythrocytes, which has significantly contributed to clarifying how hypoxia affects erythrocytes. The aim of this article is to summarize the composition of the cytoskeleton and cytoplasmic proteins of hypoxia-altered erythrocytes and explore the impact of hypoxia on their essential functions. Furthermore, we discuss the role of microRNAs in the adaptation of erythrocytes to hypoxia, providing new perspectives on hypoxia-related diseases.

Mobile phone induced EMF stress is reversed upon the use of protective devices: results from two experiments testing different boundary conditions

This work examines (a) the impact of electromagnetic fields (EMF) on heart rate variability (HRV), saliva cortisol, arterial blood oxygenation, and tympanic temperature, and (b) the potential effect of protective devices developed to counter EMF-induced stress. In a pilot study, recordings were taken during a 15-min mobile phone call emitting a high burden of EMF (electric, magnetic, high frequency) after a baseline measurement at rest with very low EMF. In a second visit, this was repeated with participants using three protective devices (insoles, pendant, mobile phone chip). In the main study, four experimental arms were employed, two of which replicated the experimental setup of the pilot study, and two of which examined the effect of only one mobile phone chip in an open-hidden-paradigm. In both experiments, exposure to EMF decreased HRV and increased salivary cortisol. In the protective experimental condition, HRV increased above and cortisol decreased below the level of the baseline measures. All differences were large and specific and not modulated by non-specific effects like placebo effects.

Erythrocyte aggregation in sudden flow arrest is linked to hyperthermia, hypoxemia, and band 3 availability

BACKGROUND

Erythrocyte aggregation is a phenomenon that is commonly found in several pathological disease states: stroke, myocardial infarction, thermal burn injury, and COVID-19. Erythrocyte aggregation is characterized by rouleaux, closely packed stacks of cells, forming three-dimensional structures. Healthy blood flow monodisperses the red blood cells (RBCs) throughout the vasculature; however, in select pathological conditions, involving hyperthermia and hypoxemia, rouleaux formation remains and results in occlusion of microvessels with decreased perfusion.

OBJECTIVES

Our objective is to address the kinetics of rouleaux formation with sudden cessation of flow in variable temperature and oxygen conditions.

METHODS

RBCs used in this in vitro system were obtained from healthy human donors. Using a vertical stop-flow system aligned with a microscope, images were acquired and analyzed for increased variation in grayscale to indicate increased aggregation. The onset of aggregation after sudden cessation of flow was determined at proscribed temperatures (37-49°C) and oxygen (0%, 10%), and in the presence and absence of 4, 4'-Diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS). Both autologous and homologous plasma were tested.

RESULTS

RBCs in autologous plasma aggregate faster and with a higher magnitude with both hyperthermia and hypoxemia. Preventing deoxyhemoglobin from binding to band 3 with DIDS (dissociates the cytoskeleton from the membrane) fully blocks aggregation. Further, RBC aggregation magnitude is greater in autologous plasma.

CONCLUSIONS

We show that the C-terminal domain of band 3 plays a pivotal role in RBC aggregation. Further, aggregation is enhanced by hyperthermia and hypoxemia.

Electrochemical Impedance Characterization of Blood Cell Suspensions. Part 1: Basic Theory and Application to Two-Phase Systems

Electrochemical impedance spectra of composite materials contain information on the topological arrangement, volume fraction, and shape of particles, as well as the dielectric properties of the matrix and particles. The objective of this study is to investigate how these parameters affect the dielectric spectrum and what reliable information can be extracted from experimental data. The main attention was focused on systems with dielectric behavior similar to that of human blood. Mostly plasma and erythrocytes determine the dielectric properties of whole blood. Erythrocytes suspended in plasma can be considered as three-phase systems with single-shelled particles. A theoretical approach based on the effective medium theory is developed for calculating the effective permittivity and conductivity of three-phase composites at a wide frequency range (from 0 to 1 GHz). A finite-difference method is applied to model three-dimensional periodic structures. A special case of two-phase materials is used to demonstrate the influence of the shape and arrangement of particles on dielectric properties. Theoretical and numerical approaches are applied to two-phase composites with spherical, spheroidal and biconcave particles and are compared with each other and with published data. It is shown that two-phase composites exhibit only β-dispersion. In contrast to the quasi-static limit, the wide-bandwidth impedance spectroscopy makes it possible to distinguish between disordered and regular arrangements of spheroidal and biconcave particles. The results can be used to analyze the dielectric properties of blood, which is very promising for various medical applications. This study of two-phase composites can be further extended to three-phase composites.

Effects of Electromagnetic Fields on Automated Blood Cell Measurements

The aim of this study is to investigate whether the electromagnetic fields associated with mobile phones and/or laptops interfere with blood cell counts of hematology analyzers. Random blood samples were analyzed on an Aperture Impedance hematology analyzer. The analysis was performed in four ways: (A) without the presence of any mobile phone or portable computer in use, (B) with mobile phones in use (B1: one mobile, B4: four mobiles), (C) with portable computers (laptops) in use (C1: one laptop, C3: three laptops), and (D) with four mobile phones and three laptops in use simultaneously. The results obtained demonstrated a statistically significant decrease in neutrophil, erythrocyte, and platelet count and an increase in lymphocyte count, mean corpuscular volume, and red blood cell distribution width, notably in the B4 group. Despite this statistical significance, in clinical practice, only the red blood cell reduction could be taken into account, as the mean difference between the A and B4 group was 60,000 cells/µL. In group D, the analyzer gave odd results after 11 measurements and finally stopped working. The combined and multiple use of mobile phones and computers affects the function of hematology analyzers, leading to false results. Consequently, the use of such electronic devices must be avoided.

Mathematical models of naturally "morphed" human erythrocytes: stomatocytes and echinocytes

We present two mathematical models that describe human red blood cells (RBCs) with morphologies that are attained naturally under certain patho-physiological conditions, namely stomatocytes and echinocytes. Muñoz San Martín et al. (Bioelectromagnetics 27:521-527, 2006) recently presented models of these shapes based on our previous set of parametric equations (Kuchel and Fackerell, Bull. Math. Biol. 61:209-220, 1999) that involve Jacobi elliptic functions and integrals. Thus, both discocytes and stomatocytes are described. Here, we derived the Cartesian forms of these new equations; and, in addition, present a realistic model of a Type III echinocyte, using prolate spheroids 'decorating' a central sphere at the vertices of an internal dodecahedron. The RBC models based on Cartesian equations have been used for representing the shape changes (morphological transformations or "morphing") that occur in RBCs under various experimental conditions; specifically, when the shape changes have been monitored by nuclear magnetic resonance (NMR) micro-imaging.

Polarizability of red blood cells with an anisotropic membrane

We predict the complex polarizability of a realistic model of a red blood cell (RBC), with an inhomogeneous dispersive and anisotropic membrane. In this model, the frequency-dependent complex electrical parameters of the individual cell layers are described by the Debye equation while the dielectric anisotropy of the cell membrane is taken into account by the different permittivities along directions normal and tangential to the membrane surface. The realistic shape of the RBC is described in terms of the Jacobi elliptic functions. To calculate the polarizability, we evoke the effective dipole moment method to determine the cell internal electric field distribution, employing an adaptive finite-element numerical approach. We have furthermore investigated the influence of the anisotropic membrane and dispersive electrical parameters of each individual cell layer on the total complex polarizability. Our findings suggest that the individual layer contribution depends on two factors: the volume of the layer and the associated induced electric field, which in turn is influenced by other layers of the cell. These results further show that the average polarizability spectra of the cell are significantly impacted by the anisotropy and associated dispersion of the cellular compartments.

Linear dielectric response of clustered living cells

The dielectric behavior of a linear cluster of two or more living cells connected by tight junctions is analyzed using a spectral method. The polarizability of this system is obtained as an expansion over the eigenmodes of the linear response operator, showing a clear separation of geometry from electric parameters. The eigenmode with the second largest eigenvalue dominates the expansion as the junction between particles tightens, but only when the applied field is aligned with the cluster axis. This effect explains a distinct low-frequency relaxation observed in the impedance spectrum of a suspension of linear clusters.

Effective dielectric properties of biological cells: generalization of the spectral density function approach

We suggest an extension of the spectral density function approach to describe the complex dielectric response of suspensions of arbitrarily shaped particles having a thin shell, in particular, biological cells. The approach is shown to give analytical results in some simple but practically important cases. In the general case, for the 3-phase systems it reduces to determination of the spectral density function for the suspension of a certain kind. Prospects and limitations of the approach, as well as practical examples, are also considered.

Polarizability of shelled particles of arbitrary shape in lossy media with an application to hematic cells

We show that within the dipole approximation the complex polarizability of shelled particles of arbitrary shape can be written as the volume of the particle times a weighted average of the electric field in the particle, with weights determined by the differences in permittivities between the shells and the external, possibly lossy media. To calculate the electric field we use an adaptive-mesh finite-element method which is very effective in handling the irregular domains, material inhomogeneities, and complex boundary conditions usually found in biophysical applications. After extensive tests with exactly solvable models, we apply the method to four types of hematic cells: platelets, T-lymphocytes, erythrocytes, and stomatocytes. Realistic shapes of erythrocytes and stomatocytes are generated by a parametrization in terms of Jacobi elliptic functions. Our results show, for example, that if the average polarizability is the main concern, a confocal ellipsoid may be used as a model for a normal erythrocyte, but not for a stomatocyte. A comparison with experimental electrorotation data shows quantitatively the effect of an accurate geometry in the derivation of electrical cell parameters from fittings of theoretical models to the experimental data.

Effect of shape on the dielectric properties of biological cell suspensions

In this note, we analyze the effect of cell shape on the dielectric and conductometric behavior of biological cell suspension, in a frequency range where the interfacial polarization characteristic of highly heterogeneous systems occurs. We consider two different families of curves, both of them capable of generating a variety of symmetric or asymmetric shapes, ranging from oval, to dog-bone like, to lemniscate curves. These curves, which differ from those generally employed in dielectric models of biological cell suspensions, describe in principle different cells including discocytes, cup-shaped cells, pear-shaped cells, dumbbells and cells with spherical protrusions or invaginations. Our analysis, based on a numerical solution of the Laplace equation by means of boundary element methods, is carried out in the attempt of separating the contributions associated with the different electrical properties of the dielectric media involved from the ones mainly associated with the shape of the cell. We determine the dielectric strength of the dielectric dispersion for a variety of cell shapes and the phenomenological correlation between this parameter of the relaxation and the cell geometry is briefly discussed and commented.

Analysis of the electric field induced forces in erythrocyte membrane pores using a realistic cell model

We calculate the induced electric stress forces on transient hydrophobic pores in the membrane of an erythrocyte exposed to an electric field. For this purpose, we use a finite element numerical technique and a realistic shape for the biconcave erythrocyte represented by a set of parametric equations in terms of Jacobi elliptic functions. The results clearly show that the electrical forces on the base and sidewalls of the pore favour the opening of the pore. A comparison of the force densities obtained for an unstretched flat membrane and for the realistic erythrocyte model shows that the thinning and curvature of the membrane cannot be neglected. We also show that the pore deformation depends strongly on the orientation of the pore with respect to the external field, and in particular is very small when the field is tangent to the membrane surface.

Modeling normal and altered human erythrocyte shapes by a new parametric equation: Application to the calculation of induced transmembrane potentials

We present simple parametric equations in terms of Jacobi elliptic functions that provide a realistic model of abnormal variations in size which maintain the biconcave shape of a normal erythrocyte (anisocytosis) and abnormal variations in shape which maintain the original volume of the erythrocyte (poikilocytosis), as well as continuous deformations from the normal to the altered shapes. We illustrate our results with parameterizations of microcytes, macrocytes, and stomatocytes, and we apply these parameterizations to the numerical calculation of the induced transmembrane voltage in microcytes, macrocytes, and stomatocytes exposed to an external electromagnetic field of 1800 MHz.