A new ferromagnetic hysteresis model for soft magnetic composite materials

A new ferromagnetic hysteresis model for soft magnetic composite materials based on their specific properties is presented. The model relies on definition of new anhysteretic magnetization based on the Cauchy-Lorentz distribution describing the maximum energy state of magnetic moments in material. Specific properties of soft magnetic composite materials (SMC) such as the presence of the bonding material, different sizes and shapes of the Fe particles, level of homogeneity of the Fe particles at the end of the SMC product treatment, and achieved overall material density during compression, are incorporated in both the anhysteretic differential magnetization susceptibility and the irreversible differential magnetization susceptibility. Together they form the total differential magnetization susceptibility that defines the new ferromagnetic hysteresis model. Genetic algorithms are used to determine the optimal values of the proposed model parameters. The simulated results show good agreement with the measured results.     

The effects of low-frequency vibrations on hepatic profile of blood

Body vibrations training has become popular in sports training, fitness activity, it is still a rare form of physical rehabilitation.. Vibrations are transmitted onto the whole body or some body parts of an exercising person via a vibration platform subjected to mechanical vertical vibrations. During the training session a participant has to maintain his body position or do exercises that engage specific muscles whilst vibrations of the platform are transmitted onto the person's body. This paper is the continuation of the earlier study covering the effects of low-frequency vibrations on selected physiological parameters of the human body. The experiments were conducted to find the answer to the question if vibration exposure (total duration of training sessions 6 hours 20 min) should produce any changes in hepatic profile of blood. Therefore a research program was undertaken at the University of Science and Technology AGH – UST to investigate the effects of low-frequency vibration on selected parameters of hepatic profile of human blood. Cyclic fluctuations of bone loading were induced by the applied harmonic vibration 3.5 Hz and amplitude 0.004 m. The experiments utilizing two vibrating platforms were performed in the Laboratory of Structural Acoustics and Biomedical Engineering AGH-UST. The applied vibrations were harmless and not annoying, in accordance with the standard PN-EN ISO 130901-1, 1998. 23 women volunteers had 19 sessions on subsequent working days, at the same time of day. during the tests the participants remained in the standing position, passive. The main hypothesis has it that short-term low-frequency vibration exposure might bring about the changes of the hepatic profile of blood, including: bilirubin (BILIRUBIN), alkaline phosphatase (Alp), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and albumin (ALBUMIN) levels. Research data indicate the low-frequency vibrations exposure produces statistically significant decrease of bilirubin level [umol/l] in blood serum from 14.05 to 9.70 for 82% of participants, the probability level being p = 0.000041.     

Real time electroporation control for accurate and safe in vivo non-viral gene therapy

In vivo cell electroporation is the basis of DNA electrotransfer, an efficient method for non-viral gene therapy using naked DNA. The electric pulses have two roles, to permeabilize the target cell plasma membrane and to transport the DNA towards or across the permeabilized membrane by electrophoresis. For efficient electrotransfer, reversible undamaging target cell permeabilization is mandatory. We report the possibility to monitor in vivo cell electroporation during pulse delivery, and to adjust the electric field strength on real time, within a few microseconds after the beginning of the pulse, to ensure efficacy and safety of the procedure. A control algorithm was elaborated, implemented in a prototype device and tested in luciferase gene electrotransfer to mice muscles. Controlled pulses resulted in protection of the tissue and high levels of luciferase in gene transfer experiments where uncorrected excessive applied voltages lead to intense muscle damage and consecutive loss of luciferase gene expression.     

Pulse Duration Dependent Asymmetry in Molecular Transmembrane Transport Due to Electroporation in H9c2 Rat Cardiac Myoblast Cells In Vitro

Electroporation (EP) is one of the successful physical methods for intracellular drug delivery, which temporarily permeabilizes plasma membrane by exposing cells to electric pulses. Orientation of cells in electric field is important for electroporation and, consequently, for transport of molecules through permeabilized plasma membrane. Uptake of molecules after electroporation are the greatest at poles of cells facing electrodes and is often asymmetrical. However, asymmetry reported was inconsistent and inconclusive—in different reports it was either preferentially anodal or cathodal. We investigated the asymmetry of polar uptake of calcium ions after electroporation with electric pulses of different durations, as the orientation of elongated cells affects electroporation to a different extent when using electric pulses of different durations in the range of 100 ns to 100 µs. The results show that with 1, 10, and 100 µs pulses, the uptake of calcium ions is greater at the pole closer to the cathode than at the pole closer to the anode. With shorter 100 ns pulses, the asymmetry is not observed. A different extent of electroporation at different parts of elongated cells, such as muscle or cardiac cells, may have an impact on electroporation-based treatments such as drug delivery, pulse-field ablation, and gene electrotransfection.     

Feasibility study for cell electroporation detection and separation by means of dielectrophoresis

Electroporation is a phenomenon during which exposure of a cell to high voltage electric pulses results in a significant increase in its membrane permeability. Aside from the fact that after the electroporation the cell membrane becomes more permeable, the cells' geometrical and electrical properties change considerably. These changes enable use of the force on dielectric particles exposed to non-uniform electric field (dielectrophoresis) for separation of non-electroporated and electroporated cells. This paper reports the results of an attempt to separate non-electroporated and electroporated cells by means of dielectrophoresis. In several experiments we managed to separate the non-electroporated and electroporated cells suspended in a medium with conductivity 0.174 S/m by exposing them to a non-uniform electric field at a frequency of 2 MHz. The behaviour of electroporated cells exposed to dielectrophoresis raises the presumption that in addition to conductivity, considerable changes in membrane permittivity occur after the electroporation.     

Optimization of bulk cell electrofusion in vitro for production of human-mouse heterohybridoma cells

Cell electrofusion is a phenomenon that occurs, when cells are in close contact and exposed to short high-voltage electric pulses. The consequence of exposure to pulses is transient and nonselective permeabilization of cell membranes. Cell electrofusion and permeabilization depend on the values of electric field parameters including amplitude, duration and number of electric pulses and direction of the electric field. In our study, we first investigated the influence of the direction of the electric field on cell fusion in two cell lines. In both cell lines, applications of pulses in two directions perpendicular to each other were the most successful. Cell electrofusion was finally used for production of human-mouse heterohybridoma cells with modified Koehler and Milstein hybridoma technology, which was not done previously. The results, obtained by cell electrofusion, are comparable to usually used polyethylene glycol mediated fusion on the same type of cells.     

Synthesis and preliminary biological evaluations of (+)-isocampholenic acid-derived amides

The synthesis of two novel (+)-isocampholenic acid-derived amines has been realized starting from commercially available (1S)-(+)-10-camphorsulfonic acid. The novel amines as well as (+)-isocampholenic acid have been used as building blocks in the construction of a library of amides using various aliphatic, aromatic, and amino acid-derived coupling partners using BPC and CDI as activating agents. Amide derivatives have been assayed against several enzymes that hold potential for the development of new drugs to battle bacterial infections and Alzheimer’s disease. Compounds 20c and 20e showed promising selective sub-micromolar inhibition of human butyrylcholinesterase \((h\hbox {BChE})\) (\(\hbox {IC}_{50}\) values \(0.80\,\pm 0.05\) and \(0.25\,\pm 0.02\,{\upmu }\hbox {M}\), respectively).     

Combined therapy of the antimetastatic compound NAMI-A and electroporation on B16F1 tumour cells in vitro

Ruthenium complex NAMI-A [ImH][trans-RuCl(4)(DMSO-S)Im] (Im = imidazole) is a potential chemotherapeutic drug in cancer treatment. Electroporation can be used to facilitate delivery of NAMI-A into cells. Suspension of B16F1 tumour cells from mouse melanoma in NAMI-A solution was exposed to a train of electric pulses. The effect of NAMI-A was determined by examining cell viability in clonogenic test. Our results show that electroporation increases the otherwise scarce in vitro effects of NAMI-A, i.e. reduces cell viability. At the conditions chosen for experiments 90% of cells survived in the presence of 1 microM NAMI-A, whereas in a combined treatment with 1 microM NAMI-A and electroporation only about 10% of cells survived.     

The effect of resting transmembrane voltage on cell electropermeabilization: a numerical analysis

The transmembrane voltage induced due to applied electric field superimposes to the resting transmembrane voltage of the cell. On the part of the cell membrane, where the transmembrane voltage exceeds the threshold transmembrane voltage, changes in the membrane occur, leading to increase in membrane permeability known as electropermeabilization. This part of the cell membrane represents the permeabilized area through which the transport of molecules occurs. In this paper we calculated numerically the permeabilized area for different electric field strength, resting transmembrane voltage, cell shape and cell orientation with respect to the applied electric field. Results show that when the transmembrane voltage is near the threshold transmembrane voltage, the permeabilized area of the cell is increased on the anodic side and decreased on the cathodic side due to the resting transmembrane voltage. In some cases, only anodic side of the cell is permeabilized. Therefore, by using bipolar pulses, the permeabilized area can be significantly increased and consequentially also the efficiency of electropermeabilization. However, when the induced transmembrane voltage is far above the threshold, the effect of the resting transmembrane voltage is negligible. These observations are valid for different cell shapes and orientations.     

Mechanisms involved in gene electrotransfer using high- and low-voltage pulses--an in vitro study

Gene electrotransfer is an established method for gene delivery which uses high-voltage pulses to increase permeability of cell membrane and thus enables transfer of genes. Currently, majority of research is focused on improving in vivo transfection efficiency, while mechanisms involved in gene electrotransfer are not completely understood. In this paper we analyze the mechanisms of gene electrotransfer by using combinations of high-voltage (HV) and low-voltage pulses (LV) in vitro. We applied different combinations of HV and LV pulses to CHO cells and determined the transfection efficiency. We obtained that short HV pulses alone were sufficient to deliver DNA into cells for optimal plasmid concentrations and that LV pulse did not increase transfection efficiency, in contrast to reported studies in vivo. However, for sub-optimal plasmid concentrations combining HV and LV pulses increased transfection rate. Our results suggest that low-voltage pulses increase transfection in conditions where plasmid concentration is low, typically in vivo where mobility of DNA is limited by the extracellular matrix. LV pulses provide additional electrophoretic force which drags DNA toward the cell membrane and consequently increase transfection efficiency, while for sufficiently high concentrations of the plasmid (usually used in vitro) electrophoretic LV pulses do not have an important role.